Contents V36 N3 FALL 2021 128 A logarithm is the inverse function of exponentiation. If bn = x, then n = logb(x). Since 23 = 8, log2(8) = 3. Since exponents can be negative, you can have negative logarithms, which represent the inverse of a number. Since ½ is the inverse of 2, the log2(½) = −1. Likewise, the log10(¹⁄₁₀) = −1 (Figure 1). Some units of measure are based on a logarithmic scale. For example, pH is based on the negative of the base-10 logarithm of the activity of the H+ ion (as measured in moles per liter). 𝑝𝑝𝑝𝑝 = −𝑙𝑙𝑙𝑙𝑙𝑙!"(𝑎𝑎#!) = 𝑙𝑙𝑙𝑙𝑙𝑙!" , 1 𝑎𝑎#! . A solution of pure water has hydrogen activity of 1 × 10−7. The reciprocal of that is 1 ×107, or 107; log10(107) = 7. So the pH of pure water is 7. Water with a pH of 6 would have a hydrogen activity of 1 ×10−6, which is 10 times as many hydrogen ions as in pure water! Figure 1. Logarithms are the inverse function of exponentiation: If bn = x, then n = logb(x). Exponentiation allows you to raise any real number (any point along a number line) to any real power. Note that x0 always equals 1, and x1 always equals x. For this reason, logb(0) is always 1 and logb(1) is always b, regardless of the value of b (i.e., regardless of the base of the logarithm). A negative exponent represents the inverse of a number (e.g., 2−1 = ½). Thus, a negative logarithm equals the logarithm of the inverse of the value: log2(½) = −1 and −log2(½) = 1. Courtesy of Richard F. Lyon via Wikimedia Commons. Base-10 logarithms are used so often that they are often just written as log (x). The natural logarithm, abbreviated ln (x), has Euler’s number (e) as its base. Euler’s number is an irrational number that is useful in many different areas of mathematics. Medical writers should be aware that viral load is often expressed in base-10 logarithms. I once edited a news article that described a patient as having a viral load of 5 copies/mL. That value was dubious: a value that low had to be below the limit of detection of any available assay. When I looked at the source material, I found out that the patient’s reported viral load was actually 5 log10 copies/mL, which meant 100,000 copies/mL. Big difference! 121 18% 37% 3% 35% 7% 110 101 106 110 115 118 120 121 FEATURE A Cognitive Model Approach to Creating Usable Health Care Content � Kirk St.Amant FEATURE Infographics and Visually Appealing Slides � Kelly Schrank RESEARCH Digital Enhancements for Primary Medical Manuscripts: A Survey on Perceptions, Challenges, and Needs of Medical Publication Professionals � Patricia Fonseca SOCIAL MEDIA Social Media for the Health Care Organization: Sharing for Good � Diane Lang and Abbie Roth FREELANCE FOCUS Brian Bass, Allie Boman, Katherine Molnar-Kimber, and Monica Nicosia What are the pros and cons of using reference management software programs to manage references? What are your preferences in terms of software? Is there a particular software that you would recommend to keep track of business expenses for tax purposes? CALENDAR OF MEETINGS IN THE SERVICE OF GOOD WRITING Counting and Measuring � Laurie Endicott Thomas Contents EDITOR-IN-CHIEF Michael G. Baker, PhD MANAGING EDITOR Jennifer Workman SECTION EDITORS Practical Matters Qing Zhou, PhD, ELS Regulatory Insights Jennifer Bridgers, MS, MWC Science Series Paul C. Dolber, PhD Social Media Jennifer Minarcik, MS Statistically Speaking Thomas M. Schindler, PhD Everyday Ethics Julie Ravo, BA, MA Members Matters Govindi (Jaya) Samaranayake, PhD Freelance Focus Ruwaida Vakil, MSc REGULAR CONTRIBUTORS Freelance Focus Brian Bass, MWC Melissa L. Bogen, ELS Sherri Bowen, MA, ELS Lori De Milto, MJ Cathryn D. Evans Gail V. Flores, PhD Phyllis Minick In the Service of Good Writing Laurie Endicott Thomas, MA, ELS EDITOR AT LARGE Haifa Kassis, MD EDITORS IN MEMORIAM Lori L. Alexander, MTPW, ELS, MWC Ronald J. Sanchez 2020–2021 PRESIDENT Gail V. Flores, PhD 2020–2021 BOARD LIAISON R. Michelle Sauer Gehring, PhD, ELS 2020–2021 STAFF LIAISON Shari Rager, MS, CAE EXECUTIVE DIRECTOR Susan Krug, MS, CAE GRAPHIC DESIGNER Amy Boches, biographics EDITORIAL OFFICE: ManagingEditor@amwa.org. Instructions for authors available at: www.amwa.org/journal. ADVERTISING: Contact marketing@amwa.org or (240) 239-0940. All advertising is subject to acceptance by AMWA and should be for products and services relevant to professional medical communicators. AMWA is not responsible for the content of advertising and does not endorse any advertiser or its products or services. SUBSCRIPTION: The AMWA Journal is published quarterly. Subscription is included with AMWA membership. Nonmember subscriptions cost is $75 per year. CONTACT: American Medical Writers Association, 30 West Gude Drive, #525, Rockville, MD 20850-4347. Phone: (240) 238-0940; Fax: (301) 294-9006; Email: amwa@amwa.org. The AMWA Journal is in the MLA International Bibliography and selectively indexed in the Cumulative Index to Nursing and Allied Health Literature (CINAHL) print index and the CINAHL database. The opinions expressed by authors contributing to the Journal do not necessarily reflect the opinions of AMWA or the institutions with which the authors are affiliated. The association accepts no responsibility for the opinions expressed by contributors to the Journal. ©2021 American Medical Writers Association. All rights reserved, worldwide. ISSN 1075-6361 AMWA JOURNAL MISSION STATEMENT In support of the mission of the American Medical Writers Association (AMWA) and to advance the broader profession, the AMWA Journal publishes content that reflects the interests, concerns, and expertise of medical communicators. Its purpose is to inform, inspire, and motivate medical communicators. M O R E V36 N3 / 2021 127 AMWA NEWS From the President � Gail V. Flores 2021 President's Award Recipient: Dikran Toroser, PhD, CMPP � Gail V. Flores The Golden Apple Award: Aaron Bernstein, PhD � Elise Eller Slate of Officer Candidates for the 2021-2022 Election � Katrina R. Burton AMWA Fellowships � Elise Eller Find Inspiration and Gain Fresh Insights at AMWA’s 2021 Medical Writing & Communication Conference