Book Review: Brief Answers to the Big Questions

Review of Brief Answers to the Big Questions, by Stephen Hawking. (New York: Bantam Books, 2018

Energetic cost of breathing, body composition, and pulmonary function in horses with recurrent airway obstruction

This study was conducted to determine whether horses with naturally occurring, severe chronic recurrent airway obstruction (RAO) 1) have a greater resting energy expenditure (REE) than control horses, 2) suffer body mass depletion, and 3) have significantly decreased REE after bronchodilation and, therefore, also 4) whether increased work of breathing contributes to the cachexia seen in some horses with RAO. Six RAO horses and six control horses underwent indirect calorimetric measures of REE and pulmonary function testing using the esophageal balloon-pneumotachograph method before and after treatment with ipratropium bromide, a parasympatholytic bronchodilator agent, at 4-h intervals for a 24-h period. Body condition scoring was performed, and an estimate of fat mass was determined via B-mode ultrasonography. O2 and CO2 fractions, respiratory airflow, respiratory rate, and pleural pressure changes were recorded, and O2 consumption, CO2 production, REE, pulmonary resistance, dynamic elastance, and tidal volume were calculated. In addition, we performed lung function testing and calorimetry both before and after sedation in two control horses. RAO horses had significantly lower body condition scores (2.8 ± 1.0 vs. 6.4 ± 1.2) and significantly greater O2 consumption than controls (4.93 ± 1.30 vs. 2.93 ± 0.70 ml·kg−1·min−1). After bronchodilation, there was no significant difference in O2 consumption between RAO horses and controls, although there remained evidence of residual airway obstruction. There was a strong correlation between O2 consumption and indexes of airway obstruction. Xylazine sedation was not associated with changes in pulmonary function but did result in markedly decreased REE in controls

Ionization in fast atom-atom collisions: The influence and scaling behavior of electron-electron and electron-nucleus interactions

We report cross sections for ionization of He coincident with electron loss from He, Li, C, O, and Ne projectiles. For He, Li, C, and O projectiles, the cross sections were measured directly, while the Ne cross sections were obtained by transforming results for He projectiles colliding with Ne. We find that, at energies of about 100–500 keV/u, neutral projectiles can ionize a He target almost as effectively as a charged projectile. The contribution to ionization due to electron-electron interactions is found to scale with the number of available projectile electrons. Comparing ionization by the bound electrons on projectiles to ionization by free electrons, we find that the cross sections for ionization by bound electrons are systematically smaller than those for free electrons

Biophysical Measurements of Cells, Microtubules, and DNA with an Atomic Force Microscope

Atomic force microscopes (AFMs) are ubiquitous in research laboratories and have recently been priced for use in teaching laboratories. Here we review several AFM platforms (Dimension 3000 by Digital Instruments, EasyScan2 by Nanosurf, ezAFM by Nanomagnetics, and TKAFM by Thorlabs) and describe various biophysical experiments that could be done in the teaching laboratory using these instruments. In particular, we focus on experiments that image biological materials and quantify biophysical parameters: 1) imaging cells to determine membrane tension, 2) imaging microtubules to determine their persistence length, 3) imaging the random walk of DNA molecules to determine their contour length, and 4) imaging stretched DNA molecules to measure the tensional force.Comment: 29 page preprint, 7 figures, 1 tabl

Continuation of Exciting Results - Particle Physics Collaboration at Yale University

With ad-hoc support during my sabbatical (fall 06) and CART FLRG (summer and fall 07) I collaborated with Professor David DeMille at Yale University on a high-profile particle/fundamental physics experiment to gain insight into nature at the level of the basic building blocks of the particles and forces that govern all of the known universe. The work has been tremendously successful: the experimental apparatus has been completed, we ran preliminary tests and we have new results (my contributions have been parts of presentations at 4 meetings in ‘07 and 2 papers in progress for 08 - this work has also resulted in a submitted patent and a Physical Review Letter (top journal in physics) in ’07 as well). These successes have verified in principle our unique experiment and ‘on the way’ toward our more significant, and challenging, goal. I will use this CART award to complete the papers in progress, work to over come the issues that we have uncovered and perform the experimental runs toward the ultimate measurements (‘Z-zero’ interactions) that we will begin taking this summer

Elementary Particle Physics Experiment at Yale and Impact on BSC: Z-zero Bosons

For the past five years I have collaborated at Yale on an elementary particle physics experiment. One of the fundamental carriers of the weak nuclear force between leptons (electrons and neutrinos) and quarks is the Z-zero particle. Our experiment probes fundamental Z-zero bosons using precision laser spectroscopy and several other purely quantum mechanical clever tricks to “coax out” effects that under normal circumstances cannot be seen. With our Z-zero probe machine we look deep within the nucleons that make up the nuclei where the weak force, perhaps the most mysterious of the forces in the Standard Model, accounts for particles over anti-particles and nuclear decays, and is the sole known source for fundamental symmetry violations in nature. As professional work is explicitly tied to how and what we teach as professors, I will talk about this research and the impact it has on BSC in the classroom and my lab

Particle Physics Collaboration at Yale University

During my sabbatical (fall 2006) I collaborated with Professor David DeMille at Yale University on one of his high-profile particle/fundamental physics experiments to gain insight into nature at the level of quarks and bosons that are part of the basic building blocks of the particles and forces that govern all of the known universe. DeMille is in the 1st of a 3-year grant with plans this summer to obtain preliminary measurements in order to secure a 3-year renewal to complete the investigation. I have become an integral member of his team and DeMille believes my continued effort is necessary to meet these goals. Our measurements have the potential to be beyond the range of those of any current or planned high-energy particle group and accelerator facility in the world, at one of the frontiers of particle/fundamental physics - to be a part of it is rare and exciting

Atomic and Molecular Structure Codes with Lab View

Atomic and molecular electronic structure (AMES) computer codes yield spectroscopic and dynamic details about atomic and molecular electron states. This information plays a fundamental and practical role in physics, chemistry, biology and industry. Advances in AMES codes have progressed in parallel with quantum theory and computer technologies yet many of the codes continue to be developed in the original scientific programming language, FORTRAN

Getting the Picture: Philosophical Issues in Visualization in Mathematics and Science

In science and mathematics, pictures and diagrams are used to represent information that is too complex to comprehend in its mathematical form. It is also used to help detect patterns, to better understand complex phenomena, and to trigger further discovery. But how do we know we are interpreting these pictures and diagrams correctly? Does use of pictures represent an inferior form of intellectual inquiry? Panel members will present examples from mathematics and physics. There will be philosophical commentary on problems of interpretation and knowledge claims that come from pictures. Following that there will be general group discussion