of Reviews Modern Physics Style Guide
Fourth Edition 2001
Edited by
Karie Friedman
Published by The American Physical Society College Park, Maryland
Copyright 2001 The American Physical Society Permission is granted to quote from this book with customary acknowledgment of the source. To reprint a section, table, or other excerpt requires the consent of the editor of this book and notication of APS. No copying fee is required when copies of sections are made for educational or research purposes by individuals or libraries (including those at government and industrial institutions). Republication or reproduction for sale of material in this publication is permitted only under license from APS. Address inquiries to the APS Associate Publisher (APS, One Physics Ellipse, College Park, MD 20740-3844). Published by The American Physical Society College Park, MD This edition was prepared by The American Institute of Physics 2 Huntington Quadrangle Melville, NY 11747-4502 Printed in the United States of America First Edition 1987 Second Edition (online only) 1995 Third Edition 1998 Fourth Edition (online only) 2001
Reviews of Modern Physics Style Guide
CONTENTS
I. INTRODUCTION II. PRELIMINARY MATTER A. Header B. Title C. Author(s) D. Afliation(s) E. Abstract F. Contents G. List of symbols and/or acronyms III. SECTION HEADINGS IV. NUMBERING OF FIGURES, TABLES, AND EQUATIONS A. Figure numbering B. Table numbering C. Equation numbering V. ACKNOWLEDGMENTS VI. APPENDICES VII. SUPPLEMENTARY MATERIAL NOT IN APPENDICES VIII. REFERENCES A. Citations in the text B. Citations in footnotes C. Format of full reference entries 1. Journal articles a. Long format b. Short format 2. Russian journal articles with English journal translations 3. Books 4. Proceedings 5. Theses, preprints, and other references D. Order of reference list IX. FOOTNOTES A. Introductory footnotes B. Textual footnotes C. Notes in tables and gure captions X. TABLES A. Table sizes B. Table captions C. Lines and space in tables D. Headings within tables XI. FIGURES A. Types of gures B. Designing and labeling gures C. Identifying gures D. Figure captions 1 1 1 1 1 1 1 2 2 2 2 2 2 2 3 3 3 3 3 4 4 4 4 4 5 5 5 5 5 6 6 6 7 7 7 7 7 8 8 8 8 8 9 XII. PUNCTUATION A. Hyphenation B. Use of the comma C. Use of parentheses D. Use of the colon E. Use of the apostrophe F. Use of exclamation points and italics XIII. ABBREVIATIONS AND ACRONYMS XIV. UNITS XV. MATHEMATICAL MATERIAL A. Characters 1. Character fonts 2. Diacritical signs 3. Subscripts and superscripts B. Abbreviations in math 1. Abbreviations designating mathematical functions 2. Abbreviations in subscripts and superscripts C. Mathematical expressions 1. When to display 2. Punctuation 3. Equation breaking (multilinear equations) 4. Equation numbering, special situations D. Bracketing 1. Grouping sequence 2. Specic bracket notation 3. Specialized notation E. Additional style guidelines 1. Placement of limits 2. Fractions 3. Multiplication signs 4. Mathematical terms 5. Radical signs and overbars ACKNOWLEDGMENTS APPENDIX A: WRITING A BETTER SCIENTIFIC ARTICLE A. ELEMENTS OF GOOD STYLE FOR EVERYONE 1. Active and passive voices 2. Economy 3. Forward momentum 4. Inviting the reader in 5. Hedging 17 17 17 18 18 19 19 9 9 10 10 10 11 11 11 11 12 12 12 12 12 13 13 13 13 13 14 14 14 14 14 15 15 15 15 15 16 16 16 16
6. Littering the landscape: abbreviations and acronyms 7. Time travel: the mixed-tenses syndrome 8. Contrast and variety 9. Grammar 10. Frequently misused words and expressions 11. Being concrete 12. Choosing a title B. ELEMENTS OF STYLE FOR NON-NATIVE WRITERS OF ENGLISH 1. Past tense and present perfect
20 20 20 21 22 23 24 24 24
2. Placing the verb early in the sentence 3. Placement of adverbs 4. Nouns as modiers 5. Articles 6. Describing gures 7. Participles and innitives 8. Covering two possibilities 9. Omitting it 10. Frequently misused words and expressions C. Conclusion APPENDIX B: JOURNAL TITLE ABBREVIATIONS
25 25 25 26 26 26 27 27 27 29 30
Reviews of Modern Physics Style Guide
I. INTRODUCTION
This guide is intended to help authors who are preparing ReVTe compuscripts for publication in Reviews of Modern Physics. The same stylistic guidelines apply, of course, in the preparation of typed copy for the journal. The editorial staff at RMP and the production staff at the American Institute of Physics appreciate your effort to follow our style in preparing your article. We all stand to gain from ityou in speedier publication and greater accuracy, and we in ease of production. A style macro package is available at the RMP website, http://rmp.aps.org/authors.html You will also nd posted on this website a sample paper prepared in ReVTe . ReVTe is the LaTe macro used to produce the standard layout and style of all American Physical Society journals, including the Physical Review journals and Reviews of Modern Physics. It enables an author to submit a le from which proof can be generated directly, without rekeyboarding. Below is a description of the features of RMP style, many of which are taken care of automatically by the style les. In addition, you will nd some remarks on the rationale behind this style and advice on preparing tables, gures, and equations. Two appendices complete the Style Guide. The rst is a short paper, Writing a Better Scientic Article, with a special subsection intended for authors whose rst language is not English. The second is a list of journal titles with their standard abbreviations for use in references. When your article is ready, send the compuscript electronically to [e-mail]. PostScript gures may also be sent electronically as separate les, named in this style: authorname_g01.eps. Do not embed the gures in the text. Reviews of Modern Physics also has an ftp site to which you can transfer your le. Contact the editorial ofce for the address and procedure. Alternatively, you can send hard copies of your text and/or gures to the RMP editorial ofce, University of Washington, Department of Physics, Physics/Astronomy Building B42, Box 351560, Seattle, WA 98195-1560. Group the gures and tables at the end of the manuscript. We look forward to receiving your article.
A. Header
Begin your text le with this header: \documentstyle[preprint,rmp,aps]{revtex}
B. Title
\title
Begin the rst word with a capital letter; thereafter capitalize only proper or trade names and chemical symbols. Words may be used in place of greek symbols in titles. The use of nonstandard abbreviations and acronyms is not allowed.
C. Author(s)
\author
If there are multiple authors, they should be ranged one above the other. Capitalize the rst letter of each name, but not the whole name. Authors should use the same form of their names in all publications (not A. L. Smith in one and Ann Smith in another) so that in author indexes like the Science Citation Index all of their work will appear in one place.
D. Afliation(s)
\address
Write out the names and postal addresses of all institutions in full, followed either by city, state, and zip code, if in the U.S., or by postal code, city, and country, if not the U.S. Do not include box numbers or street addresses. If an author has more than one afliation, each should begin a new line, without linespaces between the lines. E-mail addresses may be given as unnumbered footnotes (\footnote ), beginning Electronic address:
E. Abstract
\begin abstract . . . \end abstract
II. PRELIMINARY MATTER
The appropriate ReVTe macro is given on the right.
1
The abstract should be a concise summary of the subjects treated in the paper. It will be used as a basis for indexing and will also be published separately from the article in at least one abstract journal. Therefore it should be completely self-contained (no footnotes or numbered references) and should avoid the use of I or we. Substitute the author(s) or passive constructions for the rst person. The abstract should consist of no more than one paragraph. The rst line should not be indented.
Reviews of Modern Physics Style Guide 1
F. Contents
\tableofcontents
The contents page is generated automatically by the ReVTe macro. Every titled section and subsection of the paper will be listed here, using exactly the same wording as is used where it appears in the text. There is no need to give manuscript page numbers; printed page numbers will be lled in when the proofs are paginated. CONTENTS Introduction Basic Equations and Concepts A. Unaveraged equations B. Averaged equations III. Homogeneous Fluctuations IV. Inhomogeneous Fluctuations V. Conclusions Acknowledgments Appendix References Note that the words Table of do not appear in the heading Contents. Unnumbered sections like Acknowledgments and References begin ush with the left margin. I. II.
All capital letters. The macro numbers these headings automatically with a roman numeral and a period and uses a boldface type font. Level Two A. First subheading \subsection First word capitalized, preceded by a roman capital letter and a period. Boldface. Level Three 1. Second subheading \subsubsection First word capitalized, preceded by an arabic numeral and a period. Level Four a. Third subheading. {\it. a. Heading} First letter capitalized, preceded by a lowercase letter and a period. Italics. Heading must be preceded by a blank line.
IV. NUMBERING OF FIGURES, TABLES, AND EQUATIONS A. Figure numbering
Figures are numbered consecutively throughout the whole paper (not by section), using arabic numbers (1, 2, 3, etc.). Parts of gures are labeled (a), (b), (c), etc., with parentheses enclosing the letter. If a gure occurs in an appendix, it should be numbered to continue the sequence from the nal gure shown in the main body of the paper. When you cite a gure, use the abbreviation Fig. except at the beginning of a sentence: As can be seen in Fig. 5, the optimum . . . Figure 7(a) shows the optimum . . . Be sure to cite every gure in the text.
G. List of symbols and/or acronyms
The inclusion of a list of symbols is optional. If you choose to have one, it precedes the References and is an unnumbered section. Arrange the list alphabetically, giving the roman alphabet rst (all capitals, then all lower case), then the greek alphabet. Each symbol should begin ush with the left-hand margin and be in italics. The denition of each symbol begins ten spaces in from the left margin with a lower-case letter (proper names, of course, should be capitalized). If the full denition will not t on one line, the additional lines should also begin ten spaces from the left margin.
B. Table numbering
Tables are numbered with roman numerals (I, II, III, etc.), in order of appearance in the text. Be sure that there is a citation in the text for every table.
III. SECTION HEADINGS C. Equation numbering
There are four types or levels of headings. The rmp.sty macro generates the correct font and style for each level. All begin ush with the left-hand margin (not centered) and are set off from the text by two line spaces above and one line space below. No period follows them. The following list shows the four different levels and the appropriate style for each. Consult a recent issue of Reviews of Modern Physics for further examples. Level One I. PRINCIPAL HEADING
2 Reviews of Modern Physics Style Guide
Equations that are set off from the text (displayed) may be numbered either consecutively throughout the whole paper or by section. Numbering by sections refers only to the large main sections, that is, to those with Level One headings labeled by roman numerals. Do not break down the numbering of equations into smaller subsections. To label by section, translate the roman numeral of the section head into an arabic number, follow this by a decimal point, then give the equation number. The
2
\section
whole is enclosed by parentheses. Thus the rst equation in Sec. II would be labeled Eq. (2.1), the second would be Eq. (2.2), etc. Equations in appendices are numbered (A1), (A2), (A3), etc. For more details, see Sec. VI on appendices. The equation number is usually placed within parentheses, at the extreme right of the displayed equation, on a level with its bottom line. When referring to a numbered equation, use the abbreviation Eq. except at the beginning of a sentence: It follows from Eq. (31) that . . . Equation (1.20) illustrates . . . When referring to more than one equation, give each equation number its own set of parentheses, e.g., Expanding Eqs. (1.20)(1.23), we obtain . . . . For more details on displayed equations, see Sec. XV.C.
pendix are then numbered (B1), (B2), etc. Note that the letter and number are not separated by a space, dash, or period.
VII. SUPPLEMENTARY MATERIAL NOT IN APPENDICES
Occasionally authors wish to include in the text material that may not be of interest to all readers, and to indicate that such material may be skipped over by the general reader. Journals published at the American Institute of Physics are no longer permitted to compose this material in a smaller typeface, or to ag the beginnings of such paragraphs with a black dot. If the material is not long enough to warrant an appendix, the author is urged to consider other alternativesincluding it as part of the regular text, putting it in a footnote, or omitting it altogether. Very long tables, computer programs, multimedia, and color gure les may be deposited in the Physics Auxiliary Publication Service (PAPS) or its electronically accessible depository, E-PAPS, and the reader referred to them by means of a footnote. This service, managed by the American Institute of Physics, supplies to interested readers material that is supplementary to papers published in The American Physical Society and American Institute of Physics journals but that may be too lengthy or of too limited reader interest to be published in full in the journal. Information about E-PAPS can be obtained from the Editorial Ofce on request, or via the World Wide Web at the URL http:// www.aip.org/epaps .
V. ACKNOWLEDGMENTS
\section* Acknowledgments The acknowledgment section follows the main body of the paper and precedes any appendices. A principal heading (Level One) is used for this section, but the section is not numbered. Note that Acknowledgments is spelled without an e between the g and the m. One paragraph is suggested, with acknowledgment of nancial support listed at the end. Reviews of Modern Physics copy editors have been instructed to delete any thanks directed to referees, associate editors, or journal staff for the performance of their editorial duties.
VIII. REFERENCES VI. APPENDICES
Appendices are placed after the acknowledgments section and before the listing of references. They must have a heading (Level One), which may be in a variety of styles, illustrated below: Reviews of Modern Physics arranges the reference sections of its papers alphabetically by author. This enables the reader to scan the list of references easily and to see at a glance when the work of one person or group is represented by several articles. Since the references are not numbered, citations to them in the text must identify them by authors names and year of publication. While some contributors to the journal have complained that this form of reference is cumbersome, we believe that it actually saves the reader time by giving the essential informationauthor and yearwhere the work is mentioned, thus sparing the reader the effort of turning to the end of the paper to decode each reference number. In a typical review paper, with 200 or more references, this saving becomes nontrivial.
APPENDIX: SURVEY OF RESULTS
\appendix \section*Survey of Results
APPENDIX A: SURVEY OF RESULTS
\appendix \section Survey of Results
APPENDIX
\appendix
If there are subheadings within an appendix, they are numbered with arabic numbers, in the style of Level Two. Displayed equations in a rst or only appendix are numbered (A1), (A2), . . . . Equations in a second ap3
A. Citations in the text
The authors and years of individual references may be cited in the text in several ways, all of which employ parentheses. Here are some examples:
Reviews of Modern Physics Style Guide 3
(1) The object N 157B in the Large Magellanic Cloud shows a lled center and nonthermal spectrum at both radio and x-ray wavelengths (Clark et al., 1982). (2) The interested reader will nd good discussions of much of this work in Potter (1983), Hockney and Eastwood (1991), and Birdsall and Langdon (1995). (3) The eld of nonlinear transport, which had been initiated long before by a few pioneer papers (Landau and Kompanejez, 1934; Davydov, 1936, 1937), then entered a period of rapid development. (4) The constant C can be obtained from Cohen and Keffer (1955; see also Osheroff et al., 1980 and Roger, 1980). In example (1), et al. has been used, signifying that there are three or more co-authors. Of course, the names of all co-authors will be given in the list of full references at the end of the paper. However, there are cases in which it would be preferable to name the coauthors in the text as well, for example, if two papers by Clark and co-workers were listed in the references for 1982, one by Clark, Jones, and Smith, and the other by Clark, Lewis, and Jones. These could not be labeled 1982a and 1982b because they are not by the same group. In example (2), only the year of the reference appears in parentheses. It is unnecessary to repeat the authors name in parentheses when it occurs naturally as part of a sentence. In example (3), a list of references is given within parentheses. Note that they are arranged chronologically, with the earliest rst, and that a semicolon separates one reference from the next. When the list contains more than one work that appeared in the same year, these should be arranged alphabetically by authors names. Commas separate authors names from years. When more than one work by the same author is cited, the years are separated by commas. No and is used before the last citation.
C. Format of full reference entries
Because Reviews of Modern Physics is an archival journal and we know that our bibliographies get heavy use, we attach considerable importance to providing references that are as helpful as possible. To this end we ask our authors to be generous with the information they supply, including names of all co-authors and editors, subtitles of books and conference proceedings, titles of preprints when an article is not yet published, etc. Authors may choose between a standard, short format and a longer format that gives titles of articles and inclusive page numbers. Whichever style is used, all journal entries in the reference section must follow the same format. Examples of both styles are given below. 1. Journal articles a. Long format Alicki, Robert, John R. Klauder, and Jerzy Lewandowski, 1993, Landau-level ground-state degeneracy and its relevance for a general quantization procedure, Phys. Rev. A 48, 25382548. b. Short format Abe, F., et al. (CDF Collaboration), 2000, Phys. Rev. Lett. 84, 5716. Barrett, R. F., B. A. Robson, and W. Tobocman, 1983, Rev. Mod. Phys. 55, 155; 56, 567(E). Bethe, H. A., 1932, Z. Phys. 76, 293. Carraro, C., and M. W. Cole, 1992, J. Low Temp. Phys. 89, 597. Einstein, A., B. Podolsky, and N. Rosen, 1935, Phys. Rev. 47, 777. The rst example shows the longer style, giving both the title of the article, in quotes, and inclusive page numbers. While it is not required, we encourage our authors to provide this information. The remaining examples are in the shorter style. Note that only the rst authors name is inverted. Each authors name is followed by a comma, and the name of the last author is preceded by and. All coauthors are named for papers with ten or fewer coauthors. When there are eleven or more, they may be represented by et al. in italics. The journal volume number is in boldface. When a journal has more than one section (e.g., Nucl. Phys. A or B), separate the section letter A, B, etc. from the volume number by a space. The Barrett et al. entry shows an original article followed by an erratum that appeared in a later issue. For references requiring more than one line, indent the sec4
B. Citations in footnotes
We encourage authors to put long lists of references in footnotes if it would be cumbersome and detrimental to the ow of the article to keep them in the text. Of course, single citations are always made in the text. As footnotes should be notes and not just lists, incorporate your list of citations into a sentence, e.g., For historical background on this problem, see Adams and Withey (1952, 1970), . . . A number of theorists have proposed alternatives to this model which we shall not discuss here. They include ... See also Sec. IX.B on textual footnotes.
4 Reviews of Modern Physics Style Guide
2 1
ond and subsequent lines one space. See Appendix B for a list of standard journal abbreviations. 2. Russian journal articles with English journal translations Maximov, A. V., and V. P. Silin, 1993, Zh. Eksp. Teor. Fiz. 103, 73 [JETP 76, 39 (1993)]. List the translation journal after the original Russian journal; it is not necessary to say that the second reference is a translation. Enclose the translation reference in square brackets. Since translations sometimes appear in a later year than the original, give the year of the translation in parentheses at the end. When translation and original appear in different years, the citation in the text should be to the earlier of the two, i.e., the original Russian journal. 3. Books Barcons, X., and A. C. Fabian, 1992, Eds., The X-ray Background (Cambridge University, Cambridge, England). Feynman, R. P., and A. R. Hibbs, 1965, Quantum Mechanics and Path Integrals (McGraw-Hill, New York). Geiss, J., 1993, in Origin and Evolution of the Elements, edited by N. Prantzos, E. Vangioni-Flam, and M. Casse (Cambridge University, Cambridge, England), p. 89. Mathieu, H. J., 1984, in Thin Film and Depth Prole Analysis, edited by H. Oeschsner, Topics in Current Physics No. 37 (Springer, Berlin), p. 39. When a book is listed under the name(s) of its editor(s), use the abbreviation Ed. (Eds.) after the year. When the reference is to an article in a collection, use the words edited by after the title of the collection, and give the page number of the article at the end. Enclose the names of publishers and cities of publication in parentheses. If the book is published in more than one city, the cities of publication should be separated by slashes. The words Press, Verlag, etc. should be omitted from the publishers name. 4. Proceedings Lehar, F., 1991, in Proceedings of the 9th International Symposium on High Energy Spin Physics, Bonn, edited by K.-H. Althoff and W. Meyer (Springer, Berlin), Vol. 1, p. 113. Lingenfelter, R., and R. Ramaty, 1982, in The Galactic Center, AIP Conference Proceedings No. 83, edited by G. R. Riegler and R. D. Blandford (AIP, New York), p. 148.
5
Matsuoka, N., K. Hatanaka, T. Saito, T. Itahashi, K. Hosono, A. Shimizu, M. Kondo, F. Ohtani, and O. Cynshi, 1983, in Proceedings of the 1983 RCNP International Symposium on Light Ion Reaction Mechanism, edited by H. Ogata, T. Kammuri, and I. Katayama (Research Center for Nuclear Physics, Osaka, Japan), p. 527. The general treatment of proceedings follows that of books. Proceedings, however, can be much more difcult to locate, making it doubly important that you provide the reader with every possible clue. Spell out the whole title, including subtitle, if any, as it appears on the title page. When the proceedings are part of a series, give the series name and number after the title. Be sure to include the name and city of the publisher. If the proceedings are to be published in a special issue of a journal, say so. Do not abbreviate the words proceedings and international. 5. Theses, preprints, and other references Below are examples of the correct form for listing theses, preprints, reports, and unpublished work. Allard, F., 1991, Ph.D. thesis (University of Heidelberg). There is no need to add unpublished to a thesis or report reference. Polchinsky, J., and E. Witten, 1996, Evidence for Heterotic Type-I String Duality, preprint hep-th/ 9510169. Binette, L., 1984, Photoionisation models for liners: gas distribution and abundances, European Southern Observatory Scientic Preprint No. 350. Cowley, C. E., 1998, Phys. Rev. A (in press). Wagner, Z., 1994, unpublished. If a preprint exists, but the paper has not yet been accepted for publication, give either the preprint number or the preprint title and institution, to aid the interested reader in obtaining a copy. The preprint title is placed in quotation marks. Do not say, submitted to . . . , in preparation, or to appear. When a paper has been accepted by a journal but not yet published, give the journal name followed by (in press). Frequently such entries can be updated in proof to include volume and page numbers. If a preprint of the work is not available, the work should be cited as unpublished or private communication, with the year.
D. Order of reference list
The reference section is arranged alphabetically by author. When several works by the same author are inReviews of Modern Physics Style Guide 5
cluded, these are arranged chronologically. When more than one work by the same author is listed in the same year, they are distinguished by labeling the rst, say, 1996a, the second 1996b, etc. If all papers were by single authors, the above guidelines would be sufcient. However, multiple authorship introduces the need for a few further distinctions. Consider the following list: Smith, G. F., 1987 Smith, G. F., 1990 Smith, G. F., 1996 Smith, G. F., H. T. Dietrich, and W. K. Lee, 1998a Smith, G. F., H. T. Dietrich, and W. K. Lee, 1998b Smith, G. F., W. K. Lee, and H. Sorenson, 1998 Smith, G. F., W. K. Lee, and A. T. Washington, 1989 Smith, G. F., and L. M. Young, 1988 All works by Smith as a single author are listed rst, in chronological order. The remaining references are arranged alphabetically by surname of the second author (Dietrich, Lee, Young). When the rst two authors are the same, alphabetize according to the surnames of the third authors (e.g., Sorenson, Washington). Two works by the same group in the same year are distinguished by labeling the rst 1984a and the second 1984b. The work by Smith, Lee, and Sorenson should not be labeled 1998c, because the makeup of the group is different from that of 1998a and 1998b. Occasionally the use of a and b is extended to groups of 4 or more co-authors that are similar but not identical in makeup. This is done to simplify the task of discriminating among several choices or when the alternative would be a cumbersome citation listing all co-authors in the text. Feel free to consult the editorial ofce about cases for which you think such a bending of the rules might be warranted.
* This paper is based in part on a talk delivered at the J. Robert Oppenheimer Memorial Prize ceremonies on January 9th, 1974, at the Center for Theoretical Studies, University of Miami, Coral Gables, Florida.
Present address: Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL 61801. On leave from Brookhaven National Laboratory, Upton, NY 11973.
Electronic address: [e-mail]
An authors primary afliation (address) should be given after his or her byline and not put into a footnote. Acknowledgments of nancial support should not appear as footnotes to the title or to an authors name, but rather belong in the acknowledgment section at the end of the paper.
B. Textual footnotes
\footnote{ }
Indicate footnotes in the text by the insertion of superscript numbers, in this manner: The appearance of these data caused a furor 3 among the theorists. Acceleration, vibration, 4 temperature gradients, and temperature changes all produce stresses in the active region of the device. When punctuation is present at the point where a footnote is cited, place the superscript number after commas, periods, and quotation marks, but before colons and semicolons. Be cautious about placing a superscript footnote number immediately after quantitative material, where it might be mistaken for an exponent. In such cases, the footnote usually can be cited elsewhere in the sentence; if no other position can be used, spell out the word footnote in parentheses (footnote 4), on the line, instead of using a superscript number. Each note is in the form of a paragraph (i.e., rst line indented), beginning with a superscript number one space in from the left-hand margin. Although simple citations of sources are not treated as footnotes (see instructions for references), bibliographic material may be incorporated in footnotes, as in the following examples: Their result was also presented at Les Houches by Cor` biere (1984). Mason (1950) gives an alternate method for calculating ci .
6
2 1
IX. FOOTNOTES
Footnotes may be used in the introductory information (titles, authors, afliations), in the body of the text (to make short comments about the textual material), and in tables or gures. Note that footnotes are not used in Reviews of Modern Physics for purely bibliographic purposes, except for long lists (see Sec. VIII.B)
A. Introductory footnotes
\thanks{ }
The following symbols, as superscripts, are used (in the order listed) for footnotes to title page material: *, , , , , , . The online edition of the journal may substitute *, **, ***, etc. for these symbols, which are not readily available in electronic fonts. Here are some examples of footnotes to preliminary matter:
6 Reviews of Modern Physics Style Guide
3 A description of these early experiments can be found in Adams, 1978. The present status of such experiments is discussed in reviews by Stein (1998) and Callaghan (1999).
See Rubbias comment after G. Myatts talk at the 1973 Bonn Conference (Myatt, 1974): The important question in my opinion is whether neutral currents exist or not, not so much the value of the branching ratio (discussion after Myatts talk, p. 405).
4
rate, numbered table, complete with a descriptive caption. All such tables must be cited in text and are numbered with roman numerals consecutively in order of their appearance in the text. Assemble tables at the end of the manuscript, before the gures. Like the gures, tables will be inserted as close as possible to where they are cited in the text. Some guidelines for preparation of tables are given below. For further examples, see any recent issue of Reviews of Modern Physics.
C. Notes in tables and gure captions
Most notes in gure captions and tables are simple references to sources and can be treated in the same way as bibliographic references in the text, i.e., by naming author and year in parentheses. Examples: FIG. 1. The He data compared to the prediction of Maize and Kim (1983): dashed curve, impulse approximation; solid curve, impulse approximation plus MEC. FIG. 2. Einstein Observatory (HEAO 2) data on the x-ray spectrum of Tycho Brahes supernova remnant. From Becker et al., 1979. FIG. 3. Typical recorded spectra when argon ions are incident on thick silicon and carbon targets (adapted from Jones et al., 1972). In tables, use lower-case roman letters to identify the footnotes, placing them as superscripts to table entries or headings and placing them on-line when they replace a missing entry. Order the footnote letters consecutively row by row, and not by column. Example: TABLE X. Experimental results Benhar, 1994 . (E2/M 1) Theor. 41.0 57.5 37.3 13.7
a
A. Table sizes
Tables will print out the same width as the caption. There are four standard one-page table widths: (1) narrow (one column, 8.6 cm or 3.4 in.), \narrowtext (2) wide (two columns, 17.8 cm or 7.0 in), \widetext (3) medium (1.5 column width, 14 cm or 5.5 in.), \mediumtext (4) turned table (one-page length turned sideways, 25.4 cm or 10.0 in.). and A turned table cannot be formatted in ReVTe requires special handling by the production staff. Please identify it as such in a cover letter. In addition, to accommodate extremely wide tabular material, tables can read across facing pages (35.6 cm or 14.0 in.). This type of table also requires special handling by the production staff and should be identied in a cover letter.
3
B. Table captions
Each table that is not part of the text must have a descriptive caption. It should be as concise as possible. If it is made up of more than one sentence, treat it as a single paragraph. The caption is positioned above the table. It begins with the word table, in capital letters, followed by the appropriate roman numeral and period, and then a small amount of explanatory text. Examples:
a
Expt. 18 10 c 0.3b 0.6
Jones et al. (1993). b Barclay and Stewart (1990). c Not available.
TABLE I. Spin-orbit parameters. TABLE II. Calculated M1 matrix elements for S1 M(M1) r in 10 2 N . M rs (M1)
156
Gd,
Remember to include in the reference list at the end of the paper full entries for any sources you cite in a table or gure.
C. Lines and space in tables
A simple table needs lines in only three locations: two lines together at the beginning and end of the table and a single line separating the headings and columns of entries. A more complicated table, one made up of several
Reviews of Modern Physics Style Guide 7
X. TABLES
Tabular material of more than four lines should not remain as part of the text. It should be treated as a sepa7
parts and having more than one set of headings, will need additional space and lines. Extra space running horizontally can be used to distinguish broad groups among the entries.
rate gures. Submit two components, indicating that they are to be treated as one gure. Do not screen.
B. Designing and labeling gures
(1) Prepare hard-copy gures on standard size paper (21 28 cm or 8.5 11 in.). Larger gures are easily damaged by handling and smaller ones are sometimes overlooked or misplaced. (2) Keep in mind the column width of RMP, 8.6 cm ( 3.4 in.). The production staff reduces all line drawings and photographs, if they are in proper scale, to three basic sizes to t within the following limits: (a) narrow, to ll the width of one column; (b) wide, to ll two columns; or 1 (c) 1 2 column width, ush left, with space on the right-hand side. (3) Make symbols and lettering in proper scale in relation to the overall gure size so that reduction will not reduce clarity. Two sizes for lettering (one for on-line lettering, the other for subscripts, superscripts, and data points) is recommended. Draw symbols and lettering so that after reduction the 1 smallest of these will not be less than 1.5 mm ( 16 in.) tall. Consider also that intricate symbols tend to ll in when reduced. Solid or open symbols are easier to read. (4) Hand lettering is not acceptable. (5) Make line thickness consistent (solid and dark). Lines tend to become less distinct when reduced. (6) When shading is necessary, use diagonal or crosshatched lines. Follow the same stylistic conventions in the gures as in the rest of the paper. Hyphenation, abbreviations, symbols, and upper- and lowercase letters should be consistent throughout. (7) Label parts of gures (a), (b), (c), etc.; curves A, B, C, etc.; geometric points, angles, and lines A, B, C, etc.; or a, b, c, etc., as appropriate. (8) Treat graphs so that they are completely selfexplanatory. Label each axis (horizontal and vertical) with the quantity being plotted, including the appropriate units, which should be spaced off and enclosed in parentheses, i.e., (deg). Avoid powers of 10 if possible; instead use the appropriate prexes ` of the Systeme International (see Table II, Sec. XIV). If powers of 10 cannot be avoided the following form is preferred: R(10 4 ). (9) Decimal quantities less than 1 should include a zero to the left of the decimal point, e.g., 0.5.
D. Headings within tables
Always capitalize the rst word or abbreviation in all headings and subheadings. Column headings are separated from the body of the table by a horizontal line. They are usually dropped to the bottom of the heading area. However, units of measure that pertain to each entry in a whole column should be included in parentheses and placed as the last entry in the heading on their own line (sample 1) or spaced off from the heading on the same line (sample 2). Sample 1 Branching ratio (%) 1 2 3
Sample 2 E x (MeV) 2720 411 J 2 2
XI. FIGURES
When submitting PostScript gures electronically, each gure should be in a separate le, with the number as part of the lename, e.g., Smith_g01.eps. Do not embed the gures in the text or place tags in the text to show where they go. Our page makeup software will place them as close as possible to where they are cited, within the constraints of the two-column format. The following technical suggestions and basic style requirements should be kept in mind.
A. Types of gures
(1) Line drawings, generated by draftsman. Submit original on drafting vellum. (2) Line drawings, computer generated. Submit hardcopy printout and PostScript le. Name the le with one authors name and the gure number. (3) Continuous-tone photograph (photographs that contain variations in tone). Do not screen. Submit sharp glossy photographs. (4) Combination (composite gure, both line drawing and continuous-tone photograph). Prepare as sepa8 Reviews of Modern Physics Style Guide
C. Identifying gures
Number each gure consecutively with an arabic numeral according to the order in which it is discussed in the paper. On hard copies write the gure number and rst authors name preferably on the lower right-hand corner of each gure. If this is not possible, write them on the back of the gure with a very soft pencil. This will
8
ensure proper matching of gure and text. It is helpful to identify the top of the gure when this is not obvious from the axes or lettering. All gures must be cited in consecutive order in the text. For example, you could refer to your rst gure in one of these ways: Figure 1 shows experimental results. Experimental results are shown in Fig. 1. The results, however, are conicting (see Fig. 1). Note that the word gure is written out when it begins a sentence, but it is abbreviated at other times. The production department at AIP has page makeup software that will place each gure as close as possible to its original citation when designing the nal layout of the paper.
to all the parts, you should probably give each part its own gure number and its own caption. Finally, if the gure is from a previously published source, the source should be credited.
XII. PUNCTUATION A. Hyphenation
The purpose of hyphenation is to resolve ambiguity as to which words are being modied in multiword terms containing more than one noun. The basic rule is that words modifying modiers get hyphenated, but not words modifying nouns that are used as such. For example: consider a heavy-fermion system, composed of heavy fermions. A heavy fermion system (no hyphen) would be quite different: the system is both heavy and composed of fermions. Certain classes of two-word modiers are easily recognized. They include the following: Quantitative modiers: three-photon, double-well, many-body, 12-channel, single-particle, zero-mass, three-dimensional. Compound modiers using high, low, large, small, wide, narrow, strong, weak, hard, soft, long, or short: high-energy, low-density, large-angle, weak-coupling, hard-pion, long-range. Two-word modiers in which the second word is a past participle: collision-induced, angle-resolved, Coulombcorrected, diffusion-limited, mode-locked, paircorrelated, phase-matched, phonon-assisted, space-xed, vacuum-deposited, valence-excited. There are some exceptions to the above rule: (1) Terms that are hyphenated when used as adjectives remain unhyphenated as predicate adjectives, i.e., when they follow a form of the verb to be. For example, A block-diagonal matrix is obtained. The matrix is block diagonal. (2) The adverb ending ly implies that the adjective immediately following is being modied, so no hyphen is needed. Examples: slowly varying, strongly coupled. (3) Latin prexes can usually be joined to a word without using a hyphen: nonzero, intermolecular, superconducting, infrared. However, do not close up the two parts if a double letter other than e is produced (semiinnite, preexisting), if a proper noun is involved (nonFermi), or if closing up could change the meaning of the word (un-ionized). Chemical prexes (in italics) should be hyphenated (cis-dimethylethylene). (4) Do not hyphenate written-out names of chemical compounds when they are used as adjectives: sodium iodide crystal, alkali halide crystal.
Reviews of Modern Physics Style Guide 9
D. Figure captions
The list of gure captions is the last item of text in the manuscript or compuscript. Captions will be placed with their respective gures during page makeup. Every gure should have a caption, even though it may consist only of an abbreviated title. Example: FIG. 1. Schematic drawing of the R110 apparatus. From Camilleri et al., 1981. Give the symbol or describe the curve before you give its denition. Examples: FIG. 2. Measured and theoretical rotation-rate uncertainty as a function of integration time : , rst harmonic measurement, with the solid line being the corresponding shot noise; , second harmonic measurement, with the dashed line indicating the corresponding shotnoise limit. From Davis and Ezekiel (1981). FIG. 3. Suppression factor S for magnetic suppression: long-dashed curve, E 0.1 E B; short-dashed curve, E 10 E B; solid curve, E 1 E B. When two or more gures are grouped together as parts of one gure number, there should be one caption for the group, beginning with a title that applies to all parts, and then proceeding to individual descriptions, as necessary, for parts (a), (b), (c), etc. Example: FIG. 4. Regge diagrams for scattering in hadron-hadron collisions: (a) total scattering; (b) elastic scattering; (c) single diffractive scattering. If you cannot come up with an initial label that applies
9
(5) Self words and free words should be hyphenated (self-consistent, worry-free), but like words and wise words are closed up (spacelike, stepwise) unless they become extremely long or cumbersome. Fold words are closed up through ten (twofold, tenfold), but hyphenated above ten (11-fold, 100-fold). To sort a string of modiers, you can use a combination of hyphens and longer dashes (two-particletwohole conguration) or hyphens and a slash (two-particle/ two-hole).
Related items can share the same set of parentheses, separated by a semicolon: (hereafter EPR; Einstein, Podolsky, and Rosen, 1935). Parenthetical remarks usually do not have closing punctuation inside the parentheses (as you might expect). However, a separate and complete sentence within parentheses, beginning with a capital letter, should have its end punctuation inside: (Armitage took exception to Browns approach, as we shall see below.)
B. Use of the comma D. Use of the colon
RMP style calls for a comma before and at the end of a list. This is known as the serial comma: Grant, Komsky, Oswald, and Peters oscillating, rotating, or stationary When introducing a variable, do not set it off with commas when it immediately follows the noun that denes it: The melting temperature T m is . . . , but do use commas when another phrase intervenes: The melting temperature reported by Green, T m , is ... Use commas on either side of the following: e.g., i.e., for example, in particular, namely, respectively, say, that is. Do not use commas after thus or therefore. The most frequent misuse of the colon by RMP authors is in introducing equations. A colon should not follow a form of the verb to be and it should not come between a verb and its object or between a preposition and its object. Often a displayed equation is the object. Thus the following lead-ins to equations should not have colons, or indeed any end punctuation: We obtain The result is This reduces to Then the coordinates are given by Colons may, however, be used to introduce equations when the object has already been stated or the clause completed: We obtain the following distribution: The result is a multidimensional gamma function: Open sets can be characterized as follows: This produces a power-law series: A second question concerning the use of colons is whether to capitalize what follows them. The answer may be stated in three parts: (1) Phrases introduced by a colon do not begin with a capital letter: Furthermore, the lake has a natural noise center source: a dam. (2) A complete sentence introduced by a colon may be, but need not be, capitalized: Finally, the energies of bound surface states are calculated by means of the effective-Hamiltonian technique: Let H eff be dened by E H eff G 0 (E 1 V). (3) When more than one sentence is introduced by a colon, capitalize the rst word:
10
C. Use of parentheses
Equation numbers cited in the text should be enclosed within parentheses. To avoid having parentheses within parentheses, use square brackets for the outer pair: [see Eqs. (2) and (3)]. Figure numbers should not be enclosed in parentheses, but parts of the gures should: Figs. 4(a)4(c). When citing individual references, the most common form is to name the author, then put the year in parentheses: Mahan (1996) conrmed that . . . Lists of references can be enclosed without separate parentheses for each year: (see Jones, 1987, 1992; Armitage, 1993b; Wurtz et al., 1996). Avoid adjacent parentheses, for example, a denition or acronym followed by a reference: (hereafter EPR) (Einstein, Podolsky, and Rosen, 1935).
10 Reviews of Modern Physics Style Guide
In order to tackle Eq. (A5) we introduce the following simplications and approximations: (1) Each eigenmode in the band is excited by white noise. (2) No eigenmode beyond the band is excited. (3) Because the . . .
E. Use of the apostrophe
(1) Contractions. Contractions such as dont, havent, theyll are well established in spoken English, but they have not yet won a place in the pages of Reviews of Modern Physics. Please do not use them in your RMP article. (2) Plurals. To form the plural of a number, add s: 1980s, tens of eV. To form the plural of a symbol, add s (apostrophe s): As, xs. To form the plural of an abbreviation or an acronym, you may add either s or s: LCAOs or LCAOs. (3) Possessives. To form the possessive of a name, add s (apostrophe s), regardless of the number of syllables or nal letter: Greens, Joness, de Genness. Be careful not to create imaginary possessives by adding unneeded apostrophes to terms like Kramers doublet or Higgs eld. Although contemporary usage may be moving in the direction of Green function, the editors at RMP still prefer Greens function.
(3) Generally it is unnecessary and distracting to assign a special acronym to a paper, using the initials of its co-authors, and it may be seen as a bid for attention if one is citing ones own work. Only classic papers that are already widely known by such acronyms justify this treatment. A simple citation of the form Smith et al. (1997) is less obtrusive than four or ve capital letters and takes very little additional effort to type. (4) When using an abbreviation of a proper name as a superscript or subscript, retain the initial capital letter: E Coul or E C for Coulomb. (5) Do not use multiletter abbreviations as mathematical variables. Use the conventional symbol instead, e.g., E k , not KE for kinetic energy. An exception is the Reynolds number, conventionally written Re. (6) Avoid abbreviations that have more syllables than the original term, e.g., FW (four syllables) for framework.
XIV. UNITS
RMP uses the metric system of units. Check Books in Print under International System of Units for the most up-to-date listing of these units. At the time this Style Guide went to press, the IEEE Standards Ofce offered a version revised in 1997, and a still useful summary was that of Barry N. Taylor, Guide for the Use of the International System of Units (SI) The Metric System (DIANE Publishing Co., 1995). The following units and abbreviations are standard.
TABLE I. Standard metric units. Units ampere barn becquerel coulomb electron volt farad gram henry herz kelvin meter ohm pascal second steradian tesla volt watt weber Abbreviations A b Bq C eV f g H Hz K m Pa s sr T V W Wb
F. Use of exclamation points and italics
It is not the style of RMP to clamor for its readers attention. The use of exclamation points and italics for emphasis should be as restrained as possible. Indeed, the Editor suggests a limit of one exclamation point per article. Italics should also be used sparingly. It is conventional to italicize terms when they are introduced and dened. Beyond this, if your personal writing style employs many italics, you will nd that our copymarkers remove most of them.
XIII. ABBREVIATIONS AND ACRONYMS
Abbreviations and acronyms should be kept to a minimum in articles written for Reviews of Modern Physics. Use only a handful of the best-known or most widely used, keeping in mind that a broad audience including physicists from other subelds will be reading the article and should not be forced to learn a code at the same time. Here are a few guidelines to keep in mind. (1) Dene all abbreviations and acronyms the rst time you use them. (2) Do not use an acronym as the subject of a sentence, even though it has been previously dened or is well known. For example, replace CDWs provide . . . with Charge-density waves provide . . .
11
Reviews of Modern Physics Style Guide
11
Other units used in the article should be dened in terms of the standard units. RMP discourages the use of historic units that have been superseded in the modern physics literature. These include wave numbers for energy, oersteds and gauss for magnetic elds, atmospheres for pressure, and curies for radioactivity. (1) The number (numeral) is separated from the unit following by a full space, e.g., 1.8 MeV. (2) Most units have a single form for both singular and plural, i.e., 1.0 cm and 2.7 cm. (3) Most symbols for units are printed in lowercase roman type without periods. Units derived from proper names, however, are written with initial capital letters, i.e., coulomb (C), weber (Wb). (4) The abbreviated form of a unit must be used after a number given in numerals: 1 cm (not 1 centimeter) but the unit is written out in cases like a few centimeters. (5) Decimal multiples or submultiples of units are indicated by the use of prexes. See Table II below. The combination of prex and unit symbol is treated as a single symbol. For instance, such a combination can be raised to a power, i.e., cm 2 . Compound units are written 1 g cm 2 or g cm 2 s 2 , with a thin space between unit parts. The form 6 J/cm 3 /s is ambiguous. Write instead 6 J cm 3 s 1 , if that is what is meant.
` TABLE II. Multiplier prexes of the Systeme International. Prex centi milli micro nano pico femto atto Symbol c m n p f a Factor 10 10 10 10 10 10 10
2 3 6 9 12 15 18
ables and constants, the italic font is used for particle symbols, symbols of quantum states, and grouptheoretic designations. In general please use the following hierarchy of fonts for symbols:
TABLE III. Fonts for symbols. Lower case: Upper case: Script upper case: Boldface lower case: Boldface upper case: variables, constants, and ordinary functions matrices and functions operators three-vectors matrices
2. Diacritical signs
For a list of easily available diacritics see Table IV below. It is possible to make multilevel accents, but placing one sign above a symbol or letter and one below is often clearer. Restrict the number of oversymbols to two. The underline can appear under any conguration. TABLE IV. Diacritical signs in math.
Symbol x x I
x x
Te $\vec x $ $\tensor \rm x $ $\dot x$ $\ddot x$ $\hat x$ $\tilde x$ $\bar x$ $\underline x$
Prex kilo mega giga tera peta exa
Symbol k M G T P E
Factor 10 3 10 6 10 9 10 12 10 15 10 18
x x x x
3. Subscripts and superscripts
All available characters can be used as subscripts or superscripts. Position of subscript or superscript is dictated by standard notation. In almost all cases you should set right and left subscripts and superscripts ush against the symbol they accompany (as in the following):
XV. MATHEMATICAL MATERIAL
Mathematical symbols must be dened immediately where they are introduced. Exceptions are the fundamental constants: the velocity of light c, Plancks constant , the electronic charge e, Boltzmanns constant k or k B , and the electrons mass m e . Avoid using the same symbol for two different things. If you think that a list of symbols would be helpful to your readers, you can provide one preceding the references (see Sec. II.G).
Rx , 0
1 0
110
Agm ,
N 0
,
14
N,
,
,
14
N2 ,
A. Characters 1. Character fonts
The italic font is used for mathematical symbols and it is taken care of by the math mode. In addition to vari12 Reviews of Modern Physics Style Guide
liml
in text .
There are, however, some exceptions to this general rule. Examples appear below:
12
tensor notation: g
z ;
;
g_ \mu\nu \phi^z ^ ;\alpha molecular ions: H2 ,O2
_ ; alpha \\
tan 1 rather than arctan. The preferred notation for the logarithm to the base e is ln; log without a subscript also denotes the same function. (a) Roman multiletter abbreviations must be closed up to the argument following and separated from any preceding symbol by a thin space, (\, ), that is, Kcos Q z z 0 ,
\rm H _2 ^ , \rm O _2 ^ \\ footnotes in tables: E n a. E_n ^ \rm a . Presuperscripts or presubscripts are set ush against the symbols they accompany. In addition, it is advisable to insert an extra thin space between a presuperscript or presubscript and a preceding symbol in cases where clarity is questionable, i.e., 8p
1 u
$K\,\cos Q z z 0 ,$ K exp x 2 b 2 b 1
1/2
. 1/2 .$
$K\,\exp x^2 b_2 b_1 ^
or
d 9s zp
3
P2 .
(b) In addition, by convention it is assumed that an argument ends as soon as another function appears, i.e., sinxcosb, or at a plus or minus sign, i.e., sinx y, but if other mathematics is involved or there is any ambiguity you should insert bracketing, as in the following examples: sin x a , sinx /a,
1/2
$8p\ sigma\,^1\ Sigma_u^ \ \ rm or \ d^9s^zp ^3P_2.$ and exp x 2 b z b 1 .
The number of levels of subscripts and superscripts attached to a symbol will also affect clarity. Two double levels is generally considered the most complicated combination acceptable, i.e., M
2 i bk
(c) To treat a function of a function enclose it in bold round parentheses, i.e., gx 2 a 3/2
1 2 1/2
.
$M_ b_k^ \dag ^ \alpha_i^2 $ When additional indices are needed, insert a comma or thin space and keep the added indices on the same line, i.e., M b k ,d p ,
r,s 1 ,
(d) e and exp (for exponent) notation follow both of the preceding conventions. The choice of which form to use, e or exp, is determined by the number of characters and the complexity of form of the superscript. The e x form is appropriate when short, simple superscripts would be involved, i.e., e z , whereas exp(xx) should be used if the superscript form is complex. In the on-line form the argument should be enclosed in bracketing. 2. Abbreviations in subscripts and superscripts Abbreviations in subscripts and superscripts fall into two categories: (1) single-letter and (2) multiletter abbreviations. Most single-letter abbreviations are conventionally printed in the italic font, i.e., E C where C stands for Coulomb. Multiletter abbreviations are conventionally printed in the roman font whether they represent one or more words, i.e., E lab , where lab stands for laboratory and E HF , where HF stands for Hartree and Fock, two proper names. Please note that you should always capitalize abbreviations that represent proper names. When you are creating your own abbreviations in text do not put periods in acronyms (whether on line or in subscripts), but do insert them if you are abbreviating words that are headings in a table.
or
r s 1.
$M_ b_k,d_p , \ \ \ rm or \
\ sigma_ r,s 1 , \ sigma_ r\, s 1 $.
B. Abbreviations in math
Some abbreviations, such as those for mathematical functions and those used in superscripts or subscripts, require special handling and are discussed below. 1. Abbreviations designating mathematical functions The multiletter abbreviations of mathematical functions are always written in the roman font (i.e., sin). The standard trigonometric functions are cos, cot, sec, sin, and tan. Hyperbolic trigonometric functions add h to the end; the preferred notation for inverse functions is
13
C. Mathematical expressions
1. When to display
Reviews of Modern Physics Style Guide 13
Display (1) equations of importance, (2) all equations that are numbered, (3) those that are too long to t easily in text (over 25 characters), or (4) those that are complicated (contain built-up fractions, matrices, or matrixlike expressions). Consider, also, displaying math that contains multilevel indices, integral, summation, and product signs, with multilevel or complex limits, or any other situation in a formula that creates the need for extra vertical spacing in a text line. 2. Punctuation Even though displayed math is separated by space from the running text it still is a part of that text and needs to be punctuated accordingly. The following is an example. The nal result is
2
. . . and their respective displacement vectors are ai/2 2aj/2 and . . . Products are broken with a multiplication sign: . . . keep m 10 3 ) at . . . 4 MeV and choose ( 5.46
In addition, you may break in text at a solidus, leaving the numerator and fraction bar on the top line. The denominator will begin the continued line. See an example below:
1/2
. . . the above current is proportional to T 0 ( N 2 (0) if the injection level G ng
1 2
1,
3)
/
remains . . .
H ij where K and
J Eg
1 2
2
Wc Wv
e
KRij
,
(1) 4. Equation numbering, special situations Equation numbers are placed ush with the right margin:
1 i j k a
(2)
H 2m 2l
i
,
j
w i w j sin K 2m 2l
i
i
sin
j i
j
1/2
,
ln W l W v / 12E g
2
.
(3)
K 2m
2l
,
j
.
(5)
3. Equation breaking (multilinear equations) Mathematical expressions often need to be displayed on two or more lines (broken) because of the linelength limitations of the Reviews of Modern Physics standard two-column layout. The best place for a break is right before an operator or sign of relation. These signs should begin the next line of the equation. When it is necessary to break a product, begin the continued line with a multiplication sign. Note that the material that comes after a break can and should be aligned so that its relationship to the material on the rst line is mathematically correct. Here is an example: Nx r iN 2 r ei
r
Some situations require unique numbering. Please use the forms shown in the following examples when you encounter similar circumstances. (1) A set of equations of equal importance may be numbered to demonstrate that relationship, e.g., (1a), (1b), and (1c). (2) A principal equation and subordinate equations (those that dene quantities or variables in that equation) may be numbered (1), (1a), and (1b), etc. (3) If an equation is a variant of a previous equation (it may be separated from the original equation by other equations and/or by text), it may be numbered with the same number as the original and a prime, double prime, etc., as appropriate.
exp
ij x u r .
(4)
The LaTe version of this is \begin eqnarray N_x( \bf r ) iN_2( \bf r )& &e^ i\theta ( bf r ) \nonumber\\ & & \exp[-ij_xu( \bf r )], \end eqnarray Equations that are not displayed, but appear in text may also need to be broken. Basically the same rules apply as when breaking displayed math. Breaking at an operator or sign of relation is best. The operator or sign of relation usually begins the next line of text:
14 Reviews of Modern Physics Style Guide
D. Bracketing
1. Grouping sequence For the purpose of grouping, the sequence of bracketing preferred for Reviews of Modern Physics articles is () , working outwards in sets ( ), , and . If you have used these three sets and need additional bracketing, begin the sequence again in the same order but in bold print:
14
\bbox\ \bbox \bbox \ \bbox \bbox\
\
\bbox
n 1
\ sum_ n
1 ^\ \ infty\
For grouping situations that contain built-up material and need larger sized bracketing, it is preferable to start again at the beginning of the sequence around the built-up material, i.e.,
\ sum_ l
l
^\ \ prime\
\ prod_ n
n 1
1
\ quad
a 2
2
1/2
x 2
1/2
\ int_
\ infty ^
\ infty
0.
lim
0
\ lim_\ \ alpha \ rightarrow 0\
2. Specic bracket notation Bracketing (ordered and special) is also used to create specic notation that denes what it encloses. A list of approved specialized notation is included below. When used in an equation along with ordered bracketing, this special kind of bracketing should not alter the regular in the sequence of bracketing. The special notation following equation does not interfere with the sequence of the equation bracketing: E a 1
1
Stacking of limits, seen in the rst example, is possible, as is centering. In text, however, space limitations require that limits be treated as subscripts and superscripts. The second example above should be set n 1 in text. The stacking in the rst example would mean that any math containing that summation should be displayed or be rewritten. 2. Fractions Fractions can be built up with a fraction bar,
0. a b , c slashed with a solidus, (a b)/c, or written with a negative exponent, (a b)c
1
3. Specialized notation Plane or set of parallel planes (111) Direction [111] Class (group) of symmetry equivalent directions 111 Class (group) of symmetry equivalent planes 111 Point designated by coordinates (x,y,z) Lattice position in a unit cell (not bracketed; 1 1 1 included for your information) 2 2 2 Vector written in components (H z ,H y ,H z ) Commutator f,g Iterated commutations H 0 , H 0 ,H 1 Functionals F x Anticommutators f,g Sets x Absolute values a Determinants x Notation used to indicate at what value of the argument some quantity is to be taken s Matrices or norms f Average or expectation value , av Dirac bra-ket notation
.
In text all fractions must be either slashed or written with a negative exponent. In displayed math all three forms are allowed. Apply the following guidelines to the mathematics in your compuscript: (a) Use built-up fractions in matrix notation (instead of the slashed conguration):
2
x2 M1
0
2
2 0
0
x
2
.
x
x2
E. Additional style guidelines
1. Placement of limits In displayed math, limits are treated in the following manner:
\ sum_ \begin array c i,j,k\\i j k\end array
i, j, k i j k
(b) Use built-up fractions (instead of the slashed conguration) in display formulas: HA w 1 2 Q
2 2
c2 e 4d
2
d.
(c) Using slashed fractions in subscripts, superscripts, and limits is preferred: N
1/2
.
Reviews of Modern Physics Style Guide 15
15
(d) Use slashed or sized fractions in the numerators and denominators of built-up fractions except where excessive bracketing would obscure your meaning or slashing would interfere with continuance of notation: /6 1 /12
2
0.
(e) When slashing fractions, respect the following conventions. In mathematical formulas this is the accepted order of operations: (1) raising to a power, (2) multiplication, (3) division, (4) addition and subtraction. According to the same conventions, parentheses indicate that the operations within them are to be performed before what they contain is operated upon. Insert parentheses in ambiguous situations. For example, do not write a/b/c; write in an unambiguous form, such as a/b /c or a/ b/c , as appropriate. 3. Multiplication signs The primary use of the multiplication sign is to indiA). Do not cate a vector product of three-vectors ( use it to express a simple product except (1) when breaking a product from one line to another (described in equation breaking, Sec. XV.C.3) or (2) for other cases such as indicating dimensions (3 3 3 cm 3 ), magnication (3 ) , symbols in gures ( s), or numbers expressed in scientic notation (5.3 102 MeV). The center dot also should not be used to mean a simple product. Use the dot to represent inner products of vectors ( A). 4. Mathematical terms
The use of the following standard symbols is recommended. approximately or varies as approximately equal tends to is proportional to O( ) of the order A* complex conjugate of A Hermitian conjugate of matrix A A transpose of matrix A AT unit vector k/k k 5. Radical signs and overbars You may use radical signs (roofed only, xx) and overbars (xx ) when they go over material of six or fewer characters that are without superscripts. If the material is longer or has superscripts, alternative notation xx should be used. For xx use (xx) 1/2 and for use xx or xx a v . If the overbar means complex conjugate, then (xx) * should be used. A radical sign (roofed) cannot be used on built-up material, although an overbar can be used.
ACKNOWLEDGMENTS
I am grateful to the following people for their help and good cheer as this Style Guide went through several iterations: George F. Bertsch, James T. Glanz, Yin Ping Ho, Cheryl McDaniel, Hedy Nurk, Doug Parker, Mark Pheffer, Thomas Thrash, and Janice Wilmot. The sections on equations, tables, and gures are based upon material from the 1983 Physical Review Style and Notation Guide of Peggy Judd and Anne Waldron, used with their permission in the 1987 edition of the RMP Style Guide. Although new material and many changes have rendered these sections almost unrecognizable, the original source is acknowledged with thanks. Thank you to Ugo Fano for proposing the writing of Appendix A and to the following authors for permission to quote examples of their (good) writing in this Appendix: F. C. Adams, Paul Forman, G. Laughlin, N. David Mermin, P. J. Morrison, Virginia Trimble. Thanks, as well, to the sources of the bad examples, who though anonymous have performed a service to the readers of this guide that is warmly appreciated.
16
Reviews of Modern Physics Style Guide
16
APPENDIX A: WRITING A BETTER SCIENTIFIC ARTICLE
Karie Friedman Assistant Editor, Reviews of Modern Physics Using examples drawn from the pages of RMP, the author presents specic writing techniques that can enhance the sense of immediacy between writer and reader and improve the clarity, economy, and polish of scientic writing. The rst half of the article is devoted to elements of good style applicable by anyone, while the second half treats problems often encountered by non-native writers of English. What sets a rst-rate scientic article apart from the thousands of forgettable publications that appear in the literature every year? For a very few, content alone ensures that the paper will be widely cited. But for most, it is the way the article is written. A good article puts us in touch with a good mind (or team of good minds) at work, whose quality is revealed by clarity, economy, order, and perhaps wit. These rather abstract qualities are warmed by the authors effort to share his or her interest in the subject as if speaking with a colleague, presenting the work not as a series of cut and dried results, but as an ongoing process by which understanding is sought. The reader whose interest is thus engaged can then share the authors satisfaction as a solution begins to emerge. A number of specic writing techniques can enhance the sense of immediacy between you and your reader. In addition, avoidance of some common pitfalls will reduce dullness, wordiness, and pomposity, which contrary to popular belief are not desirable attributes in a scientic article, but represent negative values of the clarity, economy, and wit mentioned above. In this guide, I describe practical measures that you, the author, can take to give your writing greater impact, with examples drawn from the work of RMPs contributors. The guide is divided into two sections, one of more general application, for anyone interested in writing better, and the other aimed specically at the author whose rst language is not English. about naming names and pointing ngers when discussing others work. Keeping names to a minimum, such a writer introduces, say, the work of Erikson et al., and then follows with a three-page description in which the bubble formation was simulated, a constant of a 1.5 was assumed, and agreement with the model of McCray was found to within 3%. There are three problems with this approach. First, it sounds stuffy. Second, it may lead to confusion, especially if other peoples models and parameters were adopted by Erikson et al. and need to be discussed as well. After a while the reader will no longer be sure whose work is being described. And third, any effort to dissociate science from its practitioners by describing it passively is doomed to failure, since readers not only know that scientists do science, they are very interested in which scientists it could well be one of their friends or competitors. Changing to the active voice and stating who did what we simulated the bubble formation, McCray assumed a constant of a 1.5, they found will tell readers what they want to know and set the work in the context of human endeavor. The active voice also encourages economy. Compare the following pairs of sentences: A review of the main problems in this eld was given by Luo et al. Luo et al. reviewed the main problems in this eld. A discussion of intrinsic pinning is offered in Sec. VIII. In Sec. VIII we discuss intrinsic pinning. In each pair above, the active version uses fewer words. Most readers will perceive this brevity as the mark of a direct and vigorous mind. There are, of course, occasions when the passive voice is useful. Sometimes you will want to put emphasis on the thing being acted upon, by naming it at the beginning of a sentence. This problem has been the subject of intensive study ever since 1934. And, for simple variety, a modest number of passive constructions can lend grace to a piece of writing, especially when no particular agent is being obscured by them:
Reviews of Modern Physics Style Guide 17
A. Elements of good style for everyone
1. Active and passive voices You have heard this before, but it bears repeating: active sentences are more vigorous than passive ones. When you want to put more muscle into your prose style, replace Science is done by people with People do science. Writers of scientic papers often favor the passive because it relieves them of naming themselves as the ones who conducted an experiment or proposed a theory. Saying that it was thought that the magnetoresistance could provide an answer shields the person who thought so from the critical gaze of his audience and is vague enough to spread credit or blame, implying that the writer was not in alone having this idea. The passive voice also provides a way out for those who feel reticent
17
All perturbations can be naturally divided into two classes. Abstracts are another place where the passive voice is appropriate. Abstracts appear separately from the articles they describe, in on-line listings and reference works like Physics Abstracts. Use of the rst person in such an impersonal setting sounds a bit odd. (However, consider the active alternative, The author surveys . . . , The authors nd that . . . ) 2. Economy A clean, direct style shows respect for your readers time. While it is possible to be so direct as to be blunt and graceless, most scientic writing suffers from the opposite tendancy, wordiness. One exercise that helps to curb wordiness in your writing is to see how many verbnoun phrases you can replace by simple verbs. For example, make a decision experience failure place under consideration perform an experiment give indications of present a discussion of conduct an investigation make an attempt introduce a replacement decide fail consider experiment indicate discuss investigate try replace
This section presents our rationale for generalizing ... My purpose has been to provide a description of thermodynamic phase transitions. I have tried to describe thermodynamic phase transitions. Then there is the case. Personally, I am rather fond of In the rst case and in the second case, but have to grant that cases can be totally useless appendages, better amputated: for the case of in many cases it has rarely been the case that we in the case when for often we rarely when
If the writer is tempted to use in the case where, he or she should see the section on grammar below. 3. Forward momentum Here is an actual sentence from a contributor to Reviews of Modern Physics: That the wavelength of any oscillator employed must necessarily be very small follows from the circumstance that the length of an accelerator of given energy i.e., the lengths of the individual drift tubes in an accelerator with a given number of drift tubes (and hence acceleration gaps) to which a given voltage is applied, and through which a given species of ion is accelerated is proportional to the period, hence the wavelength, of the oscillation. Before publication, this sentence was edited to about two-thirds of its present length. Its problem, however, is not length per se. It suffers from the authors attempt to cover everything. The cumulative effect of multiple asides, parenthetical remarks, i.e.s, and hences is to leave the reader feeling like a passenger in a car whose driver starts up, then stops, then starts again, then stops, etc. Moreover, by the time the reader gets to the verb is proportional, he or she is likely to have forgotten the subject, the length of an accelerator. Asides and parenthetical remarks can enhance a text. They reect the way people talk and thus give a conversational tone to any piece of writing. When overused as above, however, they will kill the momentum of the article. To keep the reader moving forward, one should use them judiciously and not place more than one between a subject and its verb, where they become merely distractions. Here are some examples of sentences that use parenthetical remarks to good effect. The asides serve a variety of functions: (a) helping to organize the material, offering a tidy place in which to stow ramications of the
18
The expressions in the left-hand column need not be banished from your writing. They can be useful for creating parallels, introducing variety, or smoothing a transition. If you nd, however, that you are using a great many, be aware that you may be regarded as windy and your papers as needlessly long. A few other wordy expressions deserve mention here. One is the fact that. It can always be replaced by a more economical construction: the fact that Clark succeeded owing to the fact that despite the fact that he was unaware of the fact that Clarks success because although he was unaware
Another is the reason . . . is that and variants of this pattern. Generally, rearranging a sentence so as to start with a subject and verb produces a more vital sounding statement: The reason for solving the Cauchy problem rst is that ... We solve the Cauchy problem rst because . . . The main theme of this section is to tell why we have chosen to generalize . . .
18 Reviews of Modern Physics Style Guide
main statement; (b) drawing the readers attention forward to a subject that will be discussed further on; (c) enhancing author-reader immediacy by offering opinions crude, pathological, etc. and simply giving a more personal style to the presentation. Note that only two of the asides below are interposed between a subject and its verb, thus ensuring minimum loss of momentum. Finally, we note that the derivation, crude as it is, reveals one very important point: the precise details of the collision rules (aside from certain pathological choices to be discussed later) do not affect the form of the constitutive hydrodynamic equations. It is easy to solve this equation (since we have dropped the inconvenient, higher-order terms). Hydrodynamic ows can be obtained (albeit at considerable computational expense) from large molecular systems. The exciting lattice-gas simulations of hydrodynamics have exploited one of the strengths of the method: uctuations (to excite bifurcations), complex geometries (to exploit the ease of coding boundary conditions), or phase transitions. Either an inhibitory substance h is produced by the activator (which slows down the activator production) or a substate s is consumed during autocatalysis (whose depletion slows down the self-enhancing reaction). Some of these are long sentences, but they are perfectly clear and easy to follow. Generally, short sentences quicken the pace and long ones slow it down. The same can be said of paragraph lengths. A paragraph break allows the reader to take a breath and refocus. Provide enough of them to keep the members of your audience fresh, as this too will help keep them moving through the article. 4. Inviting the reader in Bringing the rhythms of everyday speech into an article by the use of a few asides is one way to invite the reader into your world or, at least, into the world of the topic you are writing about. Addressing the reader directly is another. That mind-to-mind contact that characterizes the best scientic articles comes about only when the writer is friendly towards the reader. This does not mean that you need to pretend a familiarity that you do not feel. It does mean that you should take pains to speak to your reader as if he or she were in the same room with you and not the recipient of an anonymous pre-recorded message. To see how well you are accomplishing this, scan your manuscript rst for questions and then for other remarks addressed to the reader.
19
If you have not up until now included questions in your writing, consider what they offer. A rhetorical question can be a wonderful device. It states the problem without your needing to say In this section I shall be considering the problem of . . . It creates the illusion that you are thinking the problem through at the very moment you are speaking. And it engages the readers participation in nding an answer. If you are very daring, you can even put the question in your readers mouth by saying, The reader may well ask . . . This allows you to disarm potential critics and capture attention for your answer. One should not underestimate, either, the power of a gracious remark to ones reader. The following wellworn phrases may seem so obvious as to be unnecessary, but they perform vital work in welcoming the reader to your intellectual world, where you will engage him or her in friendly discourse or serve as a guide over unfamiliar terrain. Let us suppose Consider Contrast this with Before we turn to Up to this point we have not Let us take a closer look at Let us now attempt Indeed, we shall see Clearly, what is happening here is that Seeing this, we should not be surprised to nd Remember that It is sometimes helpful to think of t as Going beyond this approximation brings us up against We now return to The reader is warned A cautionary remark: Many of these phrases make particularly graceful openings for paragraphs and for subsections. Your subject matter will suggest other ways of combining cordiality with critical exposition. 5. Hedging There seem to be many writers who take it as an operating principle never to commit themselves rmly to any point of view. They will hedge even simple statements of historical fact, and their conclusions sections are full of mays and mights and it would seems. In a review paper, this will not do. Part of the job of the reviewer is to describe the eld as he or she sees it. We want the reviewer to be fair, but not irresolute.
Reviews of Modern Physics Style Guide 19
A classic sign of commitment avoidance is misuse of the auxiliary verbs may and could: Schroedinger may be counted as one of the rst to propose the concept of what are now called coherent states. This term could be regarded as combining nonlinear and spatial dispersion. Actually, it would be perfectly accurate to say Schroedinger rst proposed the concept of what are now called coherent states. This term combines nonlinear and spatial dispersion. When you are condent of your facts, speak with authority. Save could, would, may, might, and other expressions of uncertainty for situations that truly warrant them. Another frequently used hedging expression is associated with, as in Under suitable circumstances, pairs of fermions are associated with bosonlike behavior. The differences between Chakravartys and Schwingers calculations are associated with differences in the value of the constant prefactor C. Under scrutiny, statements like these appear not only imprecise, but weaselly. How much better to say, with precision and conviction, Under suitable conditions, pairs of fermions exhibit bosonlike behavior The differences between Chakravartys and Schwingers calculations are due to different values of the constant prefactor C. 6. Littering the landscape: abbreviations and acronyms There is no rule at Reviews of Modern Physics that says you must replace all frequently used terms with groups of letters. On the contrary, our copy editors have been instructed to disallow excessive abbreviations, so that no article looks like alphabet soup. Readers who do not share your familiarity with the subject, but would like to learn, should not be forced to translate a private language. Limit yourself to a handful of the most widely used abbreviations and dene these where they are introduced. Even justiable and widely known abbreviations should not be used as the subject of a sentence. Thus, while you might refer to the BCS approach, change BCS found that . . . to Bardeen, Cooper, and Schrieffer found that . . .
20 Reviews of Modern Physics Style Guide
7. Time travel: the mixed-tenses syndrome Consider the following discussion. Andrews noted that the absence of Bragg peak splitting at x 0.016 is due to the small magnitude of the spontaneous deformation, which at x 0.016 should be 25 times smaller than at x 0.05. At the same time, experiments on diffuse scattering of x rays (Varma et al., 1991) indicate that homogeneous deformation regions with an average size of at least 1000 exist in the crystal even at x 0.016. This conclusion was supported by subsequent experiments. If you nd yourself a bit at sea after reading this passage, you are probably experiencing disorientation from time shifts. Either the past or the present tense may correctly be used in such a discussion, but not both. Stick to one tense per topic. For example, when discussing a paper by Smith, you can say Smith finds a heavy concentration of H, which indicates . . . or Smith found a heavy concentration of H, which indicated, but you should stay with the same tense until the end of the paragraph. 8. Contrast and variety The English language is a rich medium, offering the writer a choice of short Anglo-Saxon words and longer latinate words, as well as borrowings from French, German, and other sources. Not surprisingly, to an American ear, a judicious mix sounds most pleasing. This is how people talk and it is also easiest to read. One of the dangers of writing about physical principles and other abstractions is that one nds latinate words so useful one favors them over all others. Consider this pair of examples: I rst outline the most feasible candidate states and how one might go about distinguishing them experimentally. Next I discuss . . . An initial outline of the most feasible candidate states and of their experimental identication will be followed by discussion of . . . The rst example does use latinate words, but they are mixed with shorter, Anglo-Saxon ones. Its effect is direct and accessible, qualities strengthened by the active voice. In contrast, the heavily latinate (and passive) second sentence seems dense and pedantic. (I was interested to learn from our former Associate Editor Ugo Fano that, to an Italian ear, it is germanic words that have this association.) If you suspect that others might nd your writing a bit dry, check it for its Latin density. Do you say rst place is or or or initial? location? consists of?
20
nd use takes place takes the form looks like is needed
or or or or or or
detect, determine, establish? utilize? occurs? is represented by? appears similar to? is required, is necessary?
or (b) by rearranging the order: The answer can be found by inserting the higher number. or (c) by expanding the -ing phrase to an independent clause: When the energy density and the lifetime are compared, only a chemical storage mode makes sense. (3) Possessives before -ing words. A possessive pronoun (e.g., our, its, their) or a possessive form of a noun (Browns, the equations) should precede -ing words, as in the following examples: Right: There is no danger of the rules being broken. Wrong: There is no danger of the rule being broken. Right: This led to his locating all unstable periodic orbits up to ninth order. Wrong: This led to him locating all unstable periodic orbits up to ninth order. We denote this by N to prevent its being confused with N. Wrong: We denote this by N to prevent it being confused with N. Right: Right: A direct consequence of momentums being conserved . . . Wrong: A direct consequence of momentum being conserved . . . (4) Introducing conditions. The subjunctive mood provides a neat, simple way of stating conditions: This model requires that the system remain near equilibrium. We impose the constraint that the eigenmodes satisfy the boson commutation relation. It is important that theory be compared with experimental results. Those unfamiliar with this construction may try to strengthen it by inserting should or must before the verb. Such insertions are superuous. Wrong: Right: Wrong: Heinz required that L must be less than 8 mm. Heinz required that L be less than 8 mm. Observations of deuterium abundance demand that the density of baryons in the universe should be rather low. Observations of deuterium abundance
Reviews of Modern Physics Style Guide 21
The point is not that shorter words are better, only that a balance of long and short will be more pleasing. In the same way, a variety of sentence lengths is also pleasing. An article made up entirely of short, choppy sentences is no more to be preferred than one of long, rambling ones. When you nd that you have been favoring either short or long for awhile, slip in a bit of contrast. Here is an example of a sentence that I believe combines long and short in a tonic fashion (note the rhetorical question): Since it is almost certain (and will henceforth be assumed) that corrections to the theory are of the order of 25% even for Z as large as 64, the pragmatic reader might well ask: What can the theory do for me? 9. Grammar This guide is not intended to be a treatise on English grammar, but here is a very brief list of errors to be avoided in polished scientic writing. (1) We will and we shall. The correct form is shall for the rst person and will for the second and third. Reversing them is supposed to provide unusual emphasis e.g., We cannot review the vast literature here, but we will give a brief overview of recent work in the eld. The exchange of we will for we shall is widely accepted in spoken English, but this is one instance in which you should not write as you speak. (Another is the exclusion of contractions cant, dont, theyll, etc. from professional writing.) (2) Dangling participles. When an -ing word is used in a phrase like leaping to the obvious conclusion or inserting the higher number, the phrase should be immediately followed by the agent who is doing the leaping or the inserting. The following examples fail to provide an agent and are thus incorrect: Leaping to the obvious conclusion, the equation . . . Inserting the higher number, the answer can be found. Comparing the energy density and the lifetime, only a chemical storage mode makes sense. They can be repaired (a) by providing an agent: Leaping to the obvious conclusion, we decide that the equation . . .
21
Right:
demand that the density of baryons in the universe be rather low. (5) That and which. These two relative pronouns are not interchangeable. That is the right choice for restrictive clauses: An approach that is based on perturbation theory offers several advantages (only an approach based on perturbation theory is under consideration that is based limits or restricts the kind of approach we are talking about). Which is the right choice for nonrestrictive clauses: This approach, which is based on perturbation theory, has generated a good deal of controversy (the nonrestrictive which clause simply gives additional information the sentence would still make sense without it). Authors who choose incorrectly tend to overuse which. For a discussion of when each is appropriate, and why, I refer the reader to Wilson Folletts Modern American Usage, in the lexicon under That, which, relative. Two easy-to-remember models, however, are The house that Jack built. The umbra is surrounded by a penumbra, which is not as dark. Note that which is usually preceded by a comma. And keep in mind a third option, no which or that at all: An approach based on perturbation theory . . . , This approach, based on perturbation theory, has generated . . . (6) Where. This word is correctly used to refer to a place or a region. Common usage in the scientic literature allows it also to be used to refer to an equation. However, it should not be used for nonlocalized abstractions. Change a case where a situation where a form where to to to a case in which a situation in which a form in which
can be improved by moving also in to follow the verb or auxiliary verb: We can also adjust the parameters. It is also desirable to apply . . . The concept of the classical limit will also be discussed. (8) Starting a sentence with This. Pronouns like this or these spare us from having to repeat cumbersome phrases and provide a smooth link with what has gone before. They can, however, contribute to vagueness and lack of focus if the thing to which they refer the antecedent is not clear. To banish any doubt, provide a reminder: this approach, this procedure, this substitution, these terms. 10. Frequently misused words and expressions (1) Data. This is a plural noun and requires a plural verb e.g., The neutron scattering data are not helpful. (2) Cite and quote. To refer to an article is to cite it: Details can be found in the two papers cited above. To reprint a sentence or passage from it is to quote it. (3) Three Latin abbreviations. 1. Cf. Authors wishing to refer their readers to a gure, equation, or article sometimes write cf. Fig. 32, cf. Eq. (2.3), or cf. Orsini, 1995. They should be certain, in doing this, that they mean compare, because that is what the Latin confer means. When no comparison is being made, they should write see. The two are not interchangeable. 2. E.g. (Latin exempli gratia). Everyone knows that e.g. means for example. In English, however, it is used only between two nouns. The rst noun describes a class of things, the second describes a specic instance: . . . discussed by many authors, e.g., Brownell, 1988. . . . in several review articles (e.g., Brownell, 1988). . . . the larger mammals, e.g., elephants. The following construction, with the rst item a verb rather than a noun, is unidiomatic: See, e.g., Brownell, 1988 and should be replaced by See, for example, Brownell, 1988. 3. Et al. (Latin et alii or aliae or alia, depending on gender). And others. Use this abbreviation to refer to two or more unnamed co-authors (others), but not to a single co-author. Note that et is a whole word, not an abbreviation, and therefore should not be followed by a
22
Change in the case in which simply to When. (7) Starting a sentence with also. It is generally bad form to begin a sentence with also, not because there is a rule against this, specically, but because the adverb is then likely to be separated from the verb it modies. Sentences like these: Also we can adjust the parameters. Also it is desirable to apply the highest feasible voltage. Also the concept of the classical limit will be discussed.
22 Reviews of Modern Physics Style Guide
period. Neither should it be separated from what comes before place no comma after the rst authors name in Karliner et al. 11. Being concrete Your readers would rather hear about a bear than a mammal, a sandwich than nutrition, and a car wreck than an accident. Translating this principle into an article about lattice-gas models or gauge invariance, however, is a challenge. To meet it you need to be ready to link the everyday world with the scientic. One of the easiest places in which to do this is your introduction. This is your stepping-off point into the world of the abstract. Rather than plunging right in, you are allowed to take two or three sentences to lead your reader to the diving board. A certain irreverence helps. Consider, for example, these openings from two of RMPs more lively authors: Even scientists who have spent the last few years under large rocks cannot help having heard of Supernova 1987A in the Large Magellanic Cloud (the associated neutrino burst having readily penetrated the very largest rocks). Virginia Trimble Rev. Mod. Phys. 60, 859 (1988)
theorist. Unfortunately, it was pitched over the heads of most people in the audience, myself included. At the end of the lecture, as we were ling out of the hall, a neighbor voiced my own complaint. Yes, she said, but what did these experiments look like? What would I have seen if I just walked into the laboratory? Of course, many of your readers will already know this, but it does no harm to describe the experiment in a way that the initiated will enjoy and the uninitiated learn from. I loved it when my elementary astronomy textbook described the neutrino telescope in Homestake Gold Mine as a 400,000-liter tank of cleaning uid. The charm of contrast between the abstruse and the mundane need not be limited to the opening of a paper. Here are a few more examples: The difference between the two types of variables can be elucidated by describing two ways of watching sh. In the Eulerian picture one stays at a point and watches whatever sh happen by; in the Lagrangian picture one picks out a particular sh and keeps track of where it goes [P. J. Morrison, Rev. Mod. Phys. 70, 467 (1998)]. One can imagine an ensemble of 10 9 - 10 10M black holes that have descended from dead galaxies and are now roaming freely and hoovering up an occasional remaining star in the volume R 3 [F.C. Adams and G. Laughlin, Rev. Mod. Phys. 69, 347 (1997)]. It should be clear to anyone who has ever wrapped a rubber band around a cylinder that any mapping with winding number n can be deformed into any other mapping with winding number n, but that two mappings with distinct winding numbers cannot be deformed into one another [David Mermin, Rev. Mod. Phys. 51, 597 (1979)]. As late as the spring of 1946, neither the fact of Sloans (1941) patent application nor the concept it embodied of electrons surng in a disc-loaded waveguide was known even by those most intimately involved [(Paul Forman, Rev. Mod. Phys. 67, 417 (1995)]. Radiative uxes from 1987A are still changing on time scales short compared to journal publication time scales. [Virginia Trimble, Rev. Mod Phys. 60, 859 (1988)]. I have observed that the Hamiltonian philosophy is like avocado: you either like it or you dont [P.J. Morrison, Rev. Mod. Phys. 70, 467 (1998)]. The important thing to remember is that science is indeed done by people people who live in a world of cats, blue skies, rubber bands, and journal publication as well as in the intellectual world of concepts and relationReviews of Modern Physics Style Guide 23
It is a fundamental quantum doctrine that a measurement does not, in general, reveal a preexisting value of the measured property. . . . Setting aside the metaphysics that emerged from urgent debates and long walks in Copenhagen parks, can one point to anything in the modern quantum theory that forces on us such an act of intellectual renunciation? Or is it merely reverence for the Patriarchs that leads us to deny that a measurement reveals a value that was already there, prior to the measurement? David Mermin Rev. Mod. Phys. 65, 803 (1993) Supposing that your style is more conservative than that of the two writers above, you can still refer to the concrete, everyday world with great benet to your text. And you will be in good company. Schroedingers cat, the small dark cloud on the blue sky of physics referred to by Planck, Feynmans story of the woman with the turtle-based cosmology all have captured the imaginations of countless readers. Clever gimmicks are not necessary. You might, for example, say something about the external appearance or the setting of an experiment, especially if it is a historic one. This is quite different from showing in a diagram the placement of gates, counters, relays, ampliers, etc. I once attended a public lecture on the birth of hightemperature superconductivity, delivered by a leading
23
ships. These people are like your audience and in many cases they are your audience. Speak to them. 12. Choosing a title In the years I have worked at Reviews of Modern Physics, I have noticed an inverse correlation between length of an articles title and age of its author. Younger physicists, eager to make a splash in the literature, like titles that could serve as abstracts, spelling out the particulars of the work and sometimes running on so long that they require a reduced font to t onto the page. Perhaps these authors imagine their readers as a very large dissertation committee or think that, to be taken seriously, they must present their work with as much aplomb as they can muster. Their elders already know a large portion of their readership personally and are not intimidated by them. EXAMPLES OF SIMPLIFIED TITLES Before The diabolical nature of conical intersections of potential-energy surfaces of the same symmetry Nuclear magnetic resonance techniques as a probe of C 60 and C 60 superconductors: structural, electronic structural, and superconducting-state properties Technology for improving the resolution of large ground-based astronomical telescopes Reparametrization invariance and physical processes in stochastic growth equations Chaos in the class generated by perturbing periodic orbits The search for and discovery of the top quark
From the security of tenured positions, they are more likely to try a catchy or witty title, use language calculated to attract a wider audience, and save the details for the paper itself. There are, of course, exceptions to complicate this generalization, but whether it is a mark of my age or of my youth, I favor the simpler and shorter titles, as do RMPs Editor and Associate Editors. We often ask our authors to replace particularly cumbersome titles. Here is a selection of article titles in their Before and After versions. The Afters have all been published in Reviews of Modern Physics, whereas some of the Befores are ctitious, having been created for the sole purpose of offering a bad example. I apologize to authors who submitted perfectly good titles yet are represented in this list as providers of bad ones. And I promise never to reveal which Befores are genuine.
After Diabolical conical intersections
Nuclear magnetic resonance of C60 fulleride superconductors
Improving the resolution of ground-based telescopes Stochastic growth equations and reparametrization invariance Strange attractors and the origin of chaos
The discovery of the top quark
B. Elements of style for non-native writers of English
To write about physics in a language other than your native tongue must be a daunting undertaking, and I am continually impressed by how well RMPs contributors manage it. Nonetheless, certain problems seem to be more daunting than others, judging from the frequency with which they come up. Here are a few areas in which the non-native writer of English needs to be especially careful.
1. Past tense and present perfect Non-native speakers of English often select a twoword past tense, thinking this to be analogous to the French passe compose, for action that is completed and thoroughly in the past. Unfortunately, English is just the reverse of French in this regard. The two-word past, or present perfect (e.g., has surveyed, have shown) describes action that is recent and perhaps ongoing, whereas the simple, one-word past tense (surveyed, showed) is more appropriate for history. The sentences below show typical misuse of the present perfect, with corrections written in by hand:
24
Reviews of Modern Physics Style Guide
24
could severely limit may also be incomplete would then follow might incorrectly assume can no longer be seen had not yet received An exception is the adverb differently, which always goes after the verb: are handled differently must evolve differently could behave differently Adverbs placed at the beginning of a sentence are understood to apply to the whole statement rather than to a single verb. Common examples: 2. Placing the verb early in the sentence English-speaking readers grow impatient when forced to wait too long for a verb. The following sentences are marked to position the verb closer to the beginning of the sentence: Unfortunately Consequently Hence Analogously Moreover 4. Nouns as modiers Like German, English sometimes uses nouns as modiers: the CP conjugation operator the interaction potential the order parameter More often, however, it prefers to introduce them after the thing modied, using of or another preposition: the expansion of the universe (not the universe expansion) the reorientational dynamics of Li (not the Li reorientational dynamics) 3. Placement of adverbs In English, adverbs are more often placed before the verb than after it. While placement after the verb is not incorrect, it has an awkward and foreign sound to a native English-speaker (usually). Two cases deserve special care. First, an adverb should not be placed between a verb and its object: Wrong: Right: Wrong: Right: Impurities affect also the elastic properties. Impurities also affect the elastic properties. If we extend further the analogy... If we further extend the analogy... the wavelength of light (not the light wavelength) the concept of the coherent state (not the coherentstate concept) a rise in temperature (not a temperature rise) an upper bound for the density of matter (not a matter density upper bound) the decay of the X meson (not the X-meson decay) I can offer no hard and fast rule, as idiom is not consistent, but when in doubt you are more likely to be right placing noun modiers after the thing modied. Long strings of modiers are almost always better positioned later in the sentence. For example, the following phrases are grammatically correct, but awkward: kinetic-ballooning-mode-induced losses few- and innite-degree-of-freedom uid-mechanical systems
Reviews of Modern Physics Style Guide 25
Second, when an auxiliary verb is used, place the adverb between the auxiliary and the verb, as in the following examples: will rapidly converge has long been known
25
Rearranging these makes for a smoother sentence and eliminates the need for multiple hyphens: losses induced by the kinetic ballooning mode uid-mechanical systems with few or innite degrees of freedom. 5. Articles People whose rst language has no articles (e.g., Chinese, Japanese) tend to omit articles from their writing. The following sentences are marked to insert necessary articles:
been marked to show the proper article:
6. Describing gures When describing the curves in a diagram, choose the idiomatic English terms, solid line dashed line heavy line rather than rather than rather than full line broken line thick line
For economy, use data-point symbols ( , , , ) whenever possible, rather than words. This also eliminates the problem of how to describe the symbols in English. Finally, for greatest clarity, name the curve or give the data point rst and then give the description: , Smith et al., 2000. Solid curve, absorption as a function of energy. People whose native language uses more articles than English (e.g., Germans) often allow extra articles to creep over into the English version. The following sentences are marked to delete unnecessary articles. FIG. 10. Temporal evolution of the minimum lm 0.01: solid curves, nonlinear thickness H min for C 1 evolution as described by Eq. (4.9); dashed curves, linear evolution in accordance with Eq. (4.21) for the fastest-growing mode. From Edwards and Oron (1995), reprinted with permission of Cambridge University Press. 7. Participles and innitives Where other languages combine a noun with an innitive, English often favors a noun-participle combination: Wrong: Right: The probability to nd a given type . . . The probability of nding a given type . . . A convenient method to generate sum rules . . . A convenient method for generating sum rules . . . The idea to look for a power series . . . The idea of looking for a power series . . .
Wrong: Right:
Wrong: Right: Finally, denite articles (the) and indenite articles (a, an) are sometimes confused. A and an should be used for general statements, the for particular and specic things. The following incorrect sentences have
There are, however, important exceptions. Ability, unlike probability, should be followed by an innitive:
26
Reviews of Modern Physics Style Guide
26
A Penning trap has the ability to hold a single particle indenitely. Other exceptions: Right, as in the right to remain silent, need, as in the need to be careful see necessity below, under Frequently Misused Words and Expressions. 8. Covering two possibilities The following very efcient construction is a Europeanism rarely encountered in articles by native English speakers: With an increase (decrease) in interaction strength, the limit on the number of massless particles grows more (less) restrictive. Many editors would let this stand, guring that the reader is probably intelligent enough to sort it out, but this construction certainly violates the rule of thumb that good prose can be understood when read aloud. A native English-speaker would treat the two possibilities separately: With an increase in interaction strength, the limit on the number of massless particles grows more restrictive, whereas with a decrease it becomes less so. 9. Omitting it In the following examples, non-native speakers are tempted to insert it where idiomatic usage leaves it out:
(3) Contrary, conversely, in contrast, unlike. The expression on the contrary is used to contradict a positive statement. It has an argumentative tone. When you wish only to compare different things, use in contrast or, for opposites, conversely. Be careful with unlike, which requires two comparable nouns two people, two atoms, two Hamiltonians. A common error is to try to compare, say, scientists with models or a theory with a variable: Wrong: Unlike the work of Adams, Cohen uses . . . Right: The work of Adams, unlike that of Cohen, uses . . . or Right: Unlike Adams, Cohen uses . . . Wrong: Unlike the case of covalent crystals, here the neighboring atoms . . . Right: Here the neighboring atoms, unlike those in covalent crystals, . . . When the comparison does not involve two specic nouns, replace unlike with in contrast. Wrong: Unlike in neurophysiology . . . Right: In contrast to neurophysiology, . . . (4) Firstly. This word has fallen into disrepute and is not permitted in AIP publications. Its sisters, secondly and thirdly, are quite acceptable. One can say rst, secondly, thirdly. For parallelism, I propose rst, second, third. (5) Estimation. A false friend. This word is used subjectively in English for esteem, regard, or a high or low opinion of something, e.g., In my estimation, the contract is worthless. For objective or scientic attempts to predict a result, use an estimate or the participle estimating:
10. Frequently misused words and expressions (1) Evidently, apparently. In English these words do not carry the weight that you might think. They are not simply another way of saying It is evident that . . . or It is apparent that . . . but introduce an overtone of doubt. A native English speaker would interpret them as The evidence to date supports it (but I am reserving judgment) or It appears to be so (but the nal word is not yet in). For a more forceful statement, choose clearly or obviously, or plainly, or spell out It is evident that . . . (2) As seen, as is seen, it is seen. Native English writers would not be so bold as to tell their readers what they see. Instead, they suggest As can be seen or try to involve the reader in a shared vision, As we have seen, . . .
27
Wrong: Estimations based on Eq. (3.37) Right: Estimates based on Eq. (3.37) Wrong: This result will prove useful for the estimation of L. Right: This result will prove useful for estimating L. (6) Evidence. When experiments produce data supporting a theory, the data (plural) are referred to collectively as evidence (singular). There is no plural evidences. Moreover, there is no such verb as to evidence. Other verbs should be used, according to the circumstances: to reveal, to indicate, to suggest, to bear out, to conrm, to argue for, to support, to bear witness to, to signal. (7) Of . . . of. Sentences that employ two or more ofs in close succession are ungainly. An English-speaking writer would instinctively try to rearrange them:
Reviews of Modern Physics Style Guide 27
Poor: Better:
The probability of formation of strongly coupled clusters . . . The probability that strongly coupled clusters will form Studies of the features of turbulence in accretion disks . . . Studies of turbulence in accretion disks . . . Calibration of the estimates of the energy of the primary particles. Calibration of the energy estimates for the primary particle.
is rare or deviating from the norm. To avoid ambiguity, use single when referring to number. Ambiguous: Clearer: singular crystal surface (unusual crystal surface?) single-crystal surface (surface of one crystal)
Poor: Better: Poor: Better:
(12) Enable, allow, permit. Verbs of empowerment take an object generally the person or persons being empowered: Wrong: The experiment does not allow to distinguish between T/1nt and T 3/2. Right: The experiment does not allow one to distinguish between T/1nt and T 3/2. Wrong: This device enabled probes of new areas. Right: This device enabled Kelly to probe new areas. Or Right: This device made possible probes of new areas. Enable must have a person or pronoun as object, followed by an innitive. Allow and permit may be used like Enable (followed by person-plus-innitive) or they may take simple objects. . . . so as to allow deeper penetration. . . . which permits a lively exchange of ideas. Note that an innitive, standing alone, is not a suitable object for any of these verbs. Right: Right: which permits use of the Hamiltonian. which permits us to use the Hamiltonian.
(8) Compared to. The two most common ways of stating a comparison in a scientic paper are demonstrated by the following models: Model A: The size of the halo is small compared with the separation between galaxies. Model B: This cross section is signicantly smaller than those predicted by Eq. (23). In Model A, a noncomparative form of the adjective small, high, broad, weak, etc. is used with compared to. In Model B, a comparative form smaller, higher, broader, weaker, etc. is used with than. The error to be avoided here is to mix elements from the two models and to produce a sentence that has both a comparative adjective and compared to: Wrong: Power corrections are greater for the delta as compared to the nucleon. Model A: Power corrections for the delta are great compared to those for the nucleon. Model B: Power corrections are greater for the delta than for the nucleon. (9) Favor. An event can be energetically favored or not energetically favored. It is never energetically unfavorable. (10) Monotony. Be careful not to confuse monotonic (a mathematical sequence) with monotonous (boring). Wrong: Right: The energy per atom decreases monotonously. The energy per atom decreases monotonically.
Wrong: which permits to use the Hamiltonian. (13) Necessity. English favors the noun need over necessity, probably because it lends itself to a simpler sentence construction. Need can be followed by an innitive: The need to use low temperatures . . . The need to take into account . . . whereas necessity, in a similar position, must be followed by of and an -ing form: The necessity of using low temperatures . . . The necessity of taking into account . . . Plainly the second construction is more cumbersome. It is thus seldom used, though not incorrect.
(11) Singular. The word singular has two meanings in English. The rst is the opposite of plural. The second
28
Reviews of Modern Physics Style Guide
28
(14) Absence. A person or an element can be absent, but an event cannot. When something does not happen, scientically speaking, English prefers a simple negation to is absent. Wrong: Right: Wrong: Right: The frequency dispersion of B is absent. There is no frequency dispersion of B. The ...