Research and Education at the Crossroads of Biology and Physics

The May issue of the American Journal of Physics (my favorite journal) is a “theme issue” devoted to Research and Education at the Crossroads of Biology and Physics. In their introductory editorial, guest editors Mel Sabella and Matthew Lang outline their goals, which are similar to the objectives Russ Hobbie and I have for the 4th edition of Intermediate Physics for Medicine and Biology.

…there is often a disconnect between biology and physics. This disconnect often manifests itself in high school and college physics instruction as our students rarely come to understand how physics influences biology and how biology influences physics. In recent years, both biologists and physicists have begun to recognize the importance of cultivating stronger connections in these fields, leading to instructional innovations. One call to action comes from the National Research Council’s report, BIO2010, which stresses the importance of quantitative and computational training for future biologists and cites that sufficient expertise in physics is crucial to addressing complex issues in the life sciences. In addition, physicists who are now exploring biological contexts in instruction need the expertise of biologists. It is clear that biologists and physicists both have a great deal to offer each other and need to develop interdisciplinary workspaces…

This theme issue on the intersection of biology and physics includes papers on new advances in the fields of biological physics, new advances in the teaching of biological physics, and new advances in education research that inform and guide instruction. By presenting these strands in parallel, in a single issue, we hope to support the reader in making connections, not only at the intersection of biology and physics but also at the intersection of research, education, and education research. Understanding these connections puts us, as researchers and physics educators, in a better position to understand the central questions we face…

The infusion of Biology into Physics and Physics into Biology provides exciting new avenues of study that can inspire and motivate students, educators, and researchers at all levels. The papers in this issue are, in many ways, a call to biologists and physicists to explore this intersection, learn about the challenges and obstacles, and become excited about new areas of physics and physics education. We invite you to read through these articles, reflect, and discuss this complex intersection, and then continue the conversation at the June 2014 Gordon Research Conference titled, “Physics Research and Education: The Complex Intersection of Biology and Physics.”

And guess who has an article in this special issue? Yup, Russ and I have a paper titled “A Collection of Homework Problems About the Application of Electricity and Magnetism to Medicine and Biology.”

This article contains a collection of homework problems to help students learn how concepts from electricity and magnetism can be applied to topics in medicine and biology. The problems are at a level typical of an undergraduate electricity and magnetism class, covering topics such as nerve electrophysiology, transcranial magnetic stimulation, and magnetic resonance imaging. The goal of these problems is to train biology and medical students to use quantitative methods, and also to introduce physics and engineering students to biological phenomena.

Regular readers of this blog know that a “hobby” of mine (pun intended, Russ) is to write new homework problems to go along with our book. Some of the problems in our American Journal of Physics paper debuted in this blog. I believe that a well-crafted collection of homework problems is essential for learning biological and medical physics (remember, for them to be useful you have to do your homework). I hope you will find the problems we present in our paper to be “well-crafted”. We certainly had fun writing them. My biggest concern with our AJP paper is that the problems may be too difficult for an introductory class. The “I” in IPMB stands for “intermediate”, not “introductory”. However, most of the AJP theme issue is about the introductory physics class. Oh well; one needs to learn biological and medical physics at many levels, and the intermediate level is our specialty. If only our premed students would reach the intermediate level (sigh)….

Russ and I are hard at work on the 5th edition of our book, where many of the problems from our paper, along with additional new ones, will appear (as they say, You Ain’t Seen Nothing Yet!).

Anyone interested in teaching biological and medical physics should have a look at this AJP theme issue. And regarding that Gordon Research Conference that Sabella and Lang mention, I’m registered and have purchased my airline tickets! It should be fun. If you are interested in attending, the registration deadline is May 11 (register here). You better act fast.

National Academies Press

Getting correct and detailed information about the applications of physics to biology and medicine is important. The 4th edition of Intermediate Physics for Medicine and Biology is an excellent source of such information. Yet I know that you, dear reader, are probably saying: “Yes, but I want a FREE source of information.” Well, for those cheapskates like me, there’s some good news this week from the National Academies Press (forwarded to me via Russ Hobbie). First, what is the National Academies Press? Their website explains:

The National Academies Press (NAP) was created by the National Academies to publish the reports issued by the National Academy of Sciences, the National Academy of Engineering, the Institute of Medicine, and the National Research Council, all operating under a charter granted by the Congress of the United States. The NAP publishes more than 200 books a year on a wide range of topics in science, engineering, and health, capturing the most authoritative views on important issues in science and health policy. The institutions represented by the NAP are unique in that they attract the nation’s leading experts in every field to serve on their award-wining panels and committees. The nation turns to the work of NAP for definitive information on everything from space science to animal nutrition.

Now, what’s the good news? An email from the NAP states

As of June 2, 2011, all PDF versions of books published by the National Academies Press (NAP) will be downloadable free of charge to anyone. This includes our current catalog of more than 4,000 books plus future reports published by NAP.

Free access to our online content supports the mission of NAP—publisher for the National Academy of Sciences, National Academy of Engineering, Institute of Medicine, and National Research Council—to improve government decision making and public policy, increase public education and understanding, and promote the acquisition and dissemination of knowledge in matters involving science, engineering, technology, and health. In 1994, we began offering free content online. Before today’s announcement, all PDFs were free to download in developing countries, and 65 percent of them were available for free to any user.

Like no other organization, the National Academies can enlist the nation’s foremost scientists, engineers, health professionals, and other experts to address the scientific and technical aspects of society’s most pressing problems through the authoritative and independent reports published by NAP. We invite you to sign up for MyNAP —a new way for us to deliver free downloads of this content to loyal subscribers like you, to offer you customized communications, and to reward you with exclusive offers and discounts on our printed books.

Intermediate Physics for Medicine and Biology cites several NAP reports. For instance, in Section 9.10 about the possible effects of weak external electric and magnetic fields, Russ and I cite and quote from the NAP report Possible Health Effects of Exposure to Residential Electric and Magnetic Fields. I tested the website (free just seemed too good to be true), and was able to download a pdf version of the document with no charge (although I did have to give them my email address when I logged in). I got 379 pages of expert analysis about the biological effects of powerline fields. Russ and I quote the bottom line of this report in our book:

There is no convincing evidence that exposure to 60-Hz electric and magnetic fields causes cancer in animals... There is no evidence of any adverse effects on reproduction or development in animals, particularly mammals, from exposure to power-frequency 50- or 60-Hz electric or magnetic fields.

In Chapter 16 on the medical use of X rays, we cite three of the Biological Effects of Ionizing Radiation (BEIR) reports: V, VI, and VII. These reports provide important background about the linear nonthreshold model of radiation exposure. Then in Chapter 17 on nuclear physics and nuclear medicine we cite BEIR reports IV and VI when discussing radiation exposure caused by radon gas. The full citations listed in our book are:

"BEIR IV (1988) Committee on the Biological Effects of Ionizing Radiations. Health Risks of Radon and Other Internally Deposited Alpha-Emitters. Washington, D.C., National Academy Press.

BEIR Report V (1990) Committee on the Biological Effects of Ionizing Radiation. Health Effects of Exposure to Low Levels of Ionizing Radiation. Washington, DC, National Academy Press.

BEIR VI (1999) Committee on Health Risks of Exposure to Radon. Health Effects of Exposure to Radon. Washington, D.C., National Academy Press.

BEIR Report VII (2005) Committee to Assess Health Risks from Exposure to Low Levels of Ionizing Radiation. Health Risks from Exposure to Low Levels of Ionizing Radiation. Washington, DC, National Academy Press.

Besides the reports cited in our book, there are many others you might like to read. In a previous blog entry, I discussed the report BIO2010: Transforming Undergraduate Education for Future Research Biologists, published by NAP. You can download a copy free. It discusses how we should teach physics to future life scientists. In another blog entry I discussed the book In the Beat of a Heart, which explores biological scaling. It is also published by the NAP.

Yet another report, published just last year, that will be of interest to readers of Intermediate Physics for Medicine and Biology is the NAP report Research at the Intersection of the Physical and Life Sciences. The report summary explains the goals of the report.

Today, while it still is convenient to classify most research in the natural sciences as either biological or physical, more and more scientists are quite deliberately and consciously addressing problems lying at the intersection of these traditional areas. This report focuses on their efforts. As directed by the charges in the statement of task (see Appendix A), the goals of the committee in preparing this report are several fold. The first goal is to provide a conceptual framework for assessing work in this area—that is, a sense of coherence for those not engaged in this research about the big objectives of the field and why it is worthy of attention from fellow scientists and programmatic focus by funding agencies. The second goal is to assess current work using that framework and to point out some of the more promising opportunities for future efforts, such as research that could significantly benefit society. The third and final goal of the report is to set out strategies for realizing those benefits—ways to enable and enhance collaboration so that the United States can take full advantage of the opportunities at this intersection.

An older report that covers much of the material that is in the last half of Intermediate Physics for Medicine and Biology is Mathematics and Physics of Emerging Biomedical Imaging (1996). Finally, yet another useful report is Advancing Nuclear Medicine Through Innovation (2007).

All this and more is now available at no cost. Who says there’s no such thing as a free lunch?

How Should We Teach Physics to Future Life Scientists and Physicians?

The American Physical Society publishes a monthly newspaper, the APS News, and the back page of each issue contains an editorial that goes under the name—you guessed it—“The Back Page.” Readers of the 4th edition of Intermediate Physics for Medicine and Biology will want to read The Back Page in the March 2010 issue, subtitled “Physics for Future Physicians and Life Scientists: A Moment of Opportunity.” This excellent editorial—written by Catherine Crouch, Robert Hilborn, Suzanne Amador Kane, Timothy McKay, and Mark Reeves—champions many of the ideas that underlie our textbook. The editorial begins

How should we teach physics to future life scientists and physicians? The physics community has an exciting and timely opportunity to reshape introductory physics courses for this audience. A June 2009 report from the American Association of Medical Colleges (AAMC) and the Howard Hughes Medical Institute (HHMI), as well as the National Research Council’s Bio2010 report, clearly acknowledge the critical role physics plays in the contemporary life sciences. They also issue a persuasive call to enhance our courses to serve these students more effectively by demonstrating the foundational role of physics for understanding biological phenomena and by making it an explicit goal to develop in students the sophisticated scientific skills characteristic of our discipline. This call for change provides an opportunity for the physics community to play a major role in educating future physicians and future life science researchers.

A number of physics educators have already reshaped their courses to better address the needs of life science and premedical students, and more are actively doing so. Here we describe what these reports call for, their import for the physics community, and some key features of these reshaped courses. Our commentary is based on the discussions at an October 2009 conference (www.gwu.edu/~ipls), at which physics faculty engaged in teaching introductory physics for the life sciences (IPLS), met with life scientists and representatives of NSF, APS, AAPT, and AAMC, to take stock of these calls for change and possible responses from the physics community. Similar discussion on IPLS also took place at the 2009 APS April Meeting, the 2009 AAPT Summer Meeting, and the February 2010 APS/AAPT Joint Meeting.

One key distinction between our textbook and the work described in The Back Page editorial is that our book is aimed toward an intermediate level, while the IPLS movement is aimed at the introductory level. Like it or not, premedical students have a difficult time fitting additional physics courses into their undergraduate curriculum. I know that here at Oakland University, I’ve been able to entice only a handful of premed students to take my PHY 325 (Biological Physics) and PHY 326 (Medical Physics) classes, despite my best efforts to attract them and despite OU’s large number of students hoping to attend medical school (these classes have our two-semester introductory physics sequence as a prerequisite). So, I think there’s merit in revising the introductory physics class, which premedical students are required to take, if your goal is to influence premedical education. As The Back Page editorial states, “the challenge is to offer courses that cultivate general quantitative and scientific reasoning skills, together with a firm grounding in basic physical principles and the ability to apply those principles to living systems, all without increasing the number of courses needed to prepare for medical school.” The Back Page editorial also cites the “joint AAMC-HHMI committee … report, Scientific Foundations for Future Physicians (SFFP). This report calls for removing specific course requirements for medical school admission and focusing instead on a set of scientific and mathematical ‘competencies.’ Physics plays a significant role…”

How do you fit all the biomedical applications of physics into an already full introductory class? The Back Page editorial gives some suggestions. For instance, “an extended discussion of kinematics and projectile motion could be replaced by more study of fluids and continuum mechanics... [and] topics such as diffusion and open systems could replace the current focus on heat engines and equilibrium thermal situations.” I agree, especially with adding fluid dynamics (Chapter 1 in our book) and diffusion (Chapter 4), which I believe are absolutely essential for understanding biology. I have my own suggestions. Although Newton’s universal law of gravity, Kepler’s laws of planetary motion, and the behavior of orbiting satellites are fascinating and beautiful topics, a premed student may benefit more from the study of osmosis (Chapter 5) and sound (Chapter 13, including ultrasound). Electricity and magnetism remains a cornerstone of introductory physics (usually in a second semester of a two-semester sequence), but the emphasis could be different. For instance, Faraday’s law of induction can be illustrated using magnetic stimulation of the brain, Ampere’s law by the magnetic field around a nerve axon, and the dipole approximation by the electrocardiogram. In a previous post to this blog, I discussed how Intermediate Physics for Medicine and Biology addresses many of these issues. Russ Hobbie will be giving an invited paper about medical physics and premed students at the July 2010 meeting of the American Association of Physics Teachers. When he gives the talk it will be posted on the book website.

One way to shift the focus of an introductory physics class toward the life sciences is to create new homework problems that use elementary physics to illustrate biological applications. In the 4th edition of Introductory Physics for Medicine and Biology, Russ Hobbie and I constructed many interesting homework problems about biomedical topics. While some of these may be too advanced for an introductory class, others may (with some modification) be very useful. Indeed, teaching a traditional introductory physics class but using a well-crafted set of homework problems may go a long ways toward achieving the goals set out by The Back Page editorial.

Let me finish this blog entry by quoting the eloquent final paragraph of The Back Page editorial. Notice that the editorial ends with the same central question that began it. It is the question that motivated Russ Hobbie to write the first edition of Intermediate Physics for Medicine and Biology (published in 1978) and it is the key question that Russ and I struggled with when working on the 4th edition.

The physics community faces a challenging opportunity as it addresses the issues surrounding IPLS courses. A sizable community we serve has articulated a clear set of skills and competencies that students should master as a result of their physics education. We have for a number of decades incorporated engineering examples into our physics classes. The SFFP report asks us to respond to another important constituency. Are we ready to develop courses that will teach our students how to apply basic physical principles to the life sciences? The challenges of making significant changes in IPLS courses are daunting if we each individually try to take on the task. But with a community-wide effort, we should be able to meet this challenge. The physics community is already moving to develop and implement changes in IPLS courses, and the motivations for change are strong. The life science and medical school communities stress that a working knowledge of physical principles is essential to success in all areas of life science including the practice of medicine. Thus we see significant teaching and learning opportunities as we work to answer the question that opened our discussion: how should we teach physics to future physicians and life scientists?

BIO2010

2010 is finally here. Happy New Year! Let’s celebrate by discussing the National Research Council report BIO2010.

In 2003 the NRC released the report BIO2010: Transforming Undergraduate Education for Future Research Biologists. If I had to sum up the report in one phrase, it would be “they are signing our song.” In the 4th edition of Intermediate Physics for Medicine and Biology, Russ Hobbie and I incorporate many of the ideas championed in BIO2010. The preface of the report recommends

a comprehensive reevaluation of undergraduate science education for future biomedical researchers. In particular it calls for a renewed discussion on the ways that engineering and computer science, as well as chemistry, physics, and mathematics are presented to life science students. The conclusions of the report are based on input from chemists, physicists, and mathematicians, not just practicing research biologists. The committee recognizes that all undergraduate science education is interconnected. Changes cannot be made solely to benefit future biomedical researchers. The impact on undergraduates studying other types of biology, as well as other sciences, cannot be ignored as reforms are considered. The Bio2010 report therefore provides ideas and options suitable for various academic situations and diverse types of institutions. It is hoped that the reader will use these possibilities to initiate discussions on the goals and methods of teaching used within their own department, institution, or professional society.

The executive summary begins

The interplay of the recombinant DNA, instrumentation, and digital revolutions has profoundly transformed biological research. The confluence of these three innovations has led to important discoveries, such as the mapping of the human genome. How biologists design, perform, and analyze experiments is changing swiftly. Biological concepts and models are becoming more quantitative, and biological research has become critically dependent on concepts and methods drawn from other scientific disciplines. The connections between the biological sciences and the physical sciences, mathematics, and computer science are rapidly becoming deeper and more extensive. The ways that scientists communicate, interact, and collaborate are undergoing equally rapid and dramatic transformations, which are driven by the accessibility of vast computing power and facile information exchange over the Internet.

Readers of this blog will be particularly interested in Recommendation #1.3 of the report, dealing with the physics education required by biologists, reproduced below. In the list of concepts the report considers essential, I have indicated in brackets the sections of the 4th edition of Intermediate Physics for Medicine and Biology that address each topic. (I admit that the comparison of the report’s recommended physics topics to those topics covered in our book may be a bit unfair, because the report was referring to an introductory physics class, not an intermediate one.) Some of the connections between the report’s topics and sections in our book need additional elaboration, which I have included as footnotes.

Physics

RECOMMENDATION #1.3

The principles of physics are central to the understanding of biological processes, and are increasingly important in sophisticated measurements in biology. The committee recommends that life science majors master the key physics concepts listed below. Experience with these principles provides a simple context in which to learn the relationship between observations and mathematical description and modeling.

The typical calculus-based introductory physics course taught today was designed to serve the needs of physics, mathematics, and engineering students. It allocates a major block of time to electromagnetic theory and to many details of classical mechanics. In so doing, it does not provide the time needed for in-depth descriptions of the equally basic physics on which students can build an understanding of biology. By emphasizing exactly solvable problems, the course rarely illustrates the ways that physics can be applied to more recalcitrant problems. Illustrations involving modern biology are rarely given, and computer simulations are usually absent. Collective behaviors and systems far from equilibrium are not a traditional part of introductory physics. However, the whole notion of emergent behavior, pattern formation, and dynamical networks is so central to understanding biology, where it occurs in an extremely complex context, that it should be introduced first in physical systems, where all interactions and parameters can be clearly specified, and quantitative study is possible.

Concepts of Physics

Motion, Dynamics, and Force Laws

• Measurement¹: physical quantities [throughout], units [1.1, symbol list at the end of each chapter], time/length/mass [1.1], precision [none]
• Equations of motion²: position [Appendix B], velocity [Appendix B], acceleration [Appendix B], motion under gravity [2.7, Problem 1.28]
• Newton’s laws [1.8]: force [1.2], mass [1.12], acceleration [Appendix B], springs [Appendix F] and related material: stiffness³ [1.9], damping⁴ [1.14, 2.7, 10.6], exponential decay [2.2], harmonic motion [10.6]
• Gravitational [3.9] and spring [none] potential energy, kinetic energy [1.8], power [1.8], heat from dissipation [Problem 8.24], work [1.8]
• Electrostatic forces [6.2], charge [6.2], conductors/insulators [6.5], Coulomb’s law [6.2]
• Electric potential [6.4], current [6.8], units [6.2, 6.4, 6.6, 6.8], Ohm’s law [6.8]
• Capacitors [6.6], R [6.9] and RC [6.11] circuits
• Magnetic forces [8.1] and magnetic fields [8.2]
• Magnetic induction and induced currents [8.6]

Conservation Laws and Gobal [sic] Constraints

• Conservation of energy [3.3] and momentum⁵ [15.4]
• Conservation of charge [6.9, 7.9]
• First [3.3] and Second [3.19] Laws of thermodynamics

Thermal Processes at the Molecular Level

• Thermal motions: Brownian motion [3.10], thermal force (collisions) [none], temperature [3.5], equilibrium [3.5]
• Boltzmann’s law [3.7], kT [3.5], examples [3.8, 3.9, 3.10]
• Ideal gas statistical concepts using Boltzmann’s law, pressure [1.11]
• Diffusion limited dynamics⁶ [4.6], population dynamics [2.9, Problem 2.34]

Waves, Light, Optics, and Imaging

• Oscillators and waves [13.1]
• Geometrical optics: rays, lenses [14.12], mirrors⁷ [none]
• Optical instruments: microscopes and microscopy [Problem 14.45]
• Physical optics: interference [14.6.2] and diffraction [13.7]
• X-ray scattering [15.4] and structure determination [none]
• Particle in a box [none]; energy levels [3.2, 14.2]; spectroscopy from a quantum viewpoint [14.2, 14.3]
• Other microscopies⁸: electron [none], scanning tunneling [none], atomic force [none]

Collective Behaviors and Systems far from Equilibrium

• Liquids [1.11, 1.12, 1.14, 1.15], laminar flow [1.14], viscosity [1.14], turbulence [1.18]
• Phase transitions⁹ [Problem 3.57], pattern formation¹⁰ [10.11.5], and symmetry breaking [none]
• Dynamical networks¹¹: electrical, neural, chemical, genetic [none]

1. Russ Hobbie and I have not developed a laboratory to go along with our book, so we don’t discuss measurement, the important differences between precision and accuracy, the ideas of random versus systematic error, or error propagation.

2. Some elementary topics—such as position, velocity, and acceleration vectors—are not presented in the book, but are summarized in an Appendix (we assume they would be mastered in an introductory physics class). We analyze Newton’s second law specifically, but do not develop his three laws of motion in general.

3. We describe Young’s modulus, but we never introduce the term “stiffness.” We talk about potential energy, and especially electrical potential energy, but we don’t spend much time on mass-spring systems and never introduce the concept of elastic (or spring) potential energy.

4. The term “damping” is used only occasionally in our book, but we discuss several types of dissipative phenomena, such as viscosity, exponential decay plus a constant input, and a harmonic oscillator with friction.

5. We use conservation of momentum when we analyze Compton scattering of electrons in Chapter 15, but we never actually present conservation of momentum as a concept.

6. We don’t discuss “diffusion limited dynamics,” but we do analyze diffusion extensively in Chapter 4.

7. We analyze lenses, but not mirrors, and never analyze the reflection of light (although we spend considerable time discussing the reflection of ultrasonic waves in Chapter 13).

8. I have to admit our book is weak on microscopy: the light microscope is relegated to a homework problem, and we don’t talk at all about electron, scanning tunneling, or atomic force microscopies.

9. We discuss thermodynamic phase transitions in a homework problem, but I believe that the report refers more generally to phase transitions that occur in condensed matter physics (e.g., the Ising model), which we do not discuss.

10. We touch on pattern formation in Chapter 10, and in particular in Problems 10.39 and 10.40 that describe wave propagation in the heart using a cellular automaton. But we do not analyze pattern formation (such as Turing patterns) in detail. Symmetry breaking is not mentioned.

11. We don’t discuss neural networks, or other related topics such as emergent behavior. We can only cover so much in one book.

I may be biased, but I believe that the 4th edition of Intermediate Physics for Medicine and Biology does a pretty good job of implementing the BIO2010 report suggestions into a textbook on physics for biologists. With 2010 now here, it’s important to remind aspiring biology students about the importance of physics in their undergraduate education.

Teaching Biological Physics

The March 2005 issue of the magazine Physics Today contains an article by Goldstein, Nelson and Powers about “Teaching Biological Physics.” Many of the ideas they champion apply to classes taught from the 4th edition of Intermediate Physics for Medicine and Biology. Goldstein et al. write

Over the past few years, people trained in physics and working in physics departments have taken an unprecedented interest in biological problems. A host of new experimental and theoretical techniques has opened up the quantitative study of systems ranging from single molecules to networks of simple agents performing complex collective tasks. Many departments have begun aggressive programs to hire faculty into the emerging field of biological physics. Engineering departments, too, are investing in the interface of the life and physical sciences, both in bioengineering and in related areas such as chemical engineering, solid mechanics, and materials.

Not surprisingly, the new faculty members, like their colleagues, are interested in teaching subjects that excite them. Meanwhile, physical-science students are beginning to demand courses relevant to the life sciences. And high-level reports such as the National Research Council's Bio2010 have emerged to stress the importance of quantitative, physics-based thinking for future life scientists...