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Full-Text Articles in Physics
Mechanisms Of Small Molecule-Dna Interactions Probed By Single-Molecule Force Spectroscopy, Ali A. Almaqwashi, Thayaparan Paramanathan, Ioulia Rouzina, Mark C. Williams
Mechanisms Of Small Molecule-Dna Interactions Probed By Single-Molecule Force Spectroscopy, Ali A. Almaqwashi, Thayaparan Paramanathan, Ioulia Rouzina, Mark C. Williams
Physics Faculty Publications
There is a wide range of applications for non-covalent DNA binding ligands, and optimization of such interactions requires detailed understanding of the binding mechanisms. One important class of these ligands is that of intercalators, which bind DNA by inserting aromatic moieties between adjacent DNA base pairs. Characterizing the dynamic and equilibrium aspects of DNA-intercalator complex assembly may allow optimization of DNA binding for specific functions. Single-molecule force spectroscopy studies have recently revealed new details about the molecular mechanisms governing DNA intercalation. These studies can provide the binding kinetics and affinity as well as determining the magnitude of the double helix …
Biophysical Measurements Of Cells, Microtubules, And Dna With An Atomic Force Microscope, Luka M. Devenica, Clay Contee, Raysa Cabrejo, Matthew Kurek, Edward F. Deveney, Ashley R. Carter
Biophysical Measurements Of Cells, Microtubules, And Dna With An Atomic Force Microscope, Luka M. Devenica, Clay Contee, Raysa Cabrejo, Matthew Kurek, Edward F. Deveney, Ashley R. Carter
Physics Faculty Publications
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 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 (cells, microtubules, and DNA) and quantify biophysical parameters including membrane tension, persistence length, contour length, and the drag force.
Repeatability Of The Seasonal Variations Of Ozone Near The Mesopause From Observations Of The 11.072-Ghz Line, Alan E. E. Rogers, P. P. Erickson, V. L. Fish, J. J. Kittredge, S. S. Danford, J. M. Marr, Martina Arndt, J. Sarabia, D. Costa, S. K. May
Repeatability Of The Seasonal Variations Of Ozone Near The Mesopause From Observations Of The 11.072-Ghz Line, Alan E. E. Rogers, P. P. Erickson, V. L. Fish, J. J. Kittredge, S. S. Danford, J. M. Marr, Martina Arndt, J. Sarabia, D. Costa, S. K. May
Physics Faculty Publications
Ground-based observations of the 11.072-GHz line of ozone were made from January 2008 through the middle of September 2011 to estimate the maximum in the nighttime ozone in the upper mesosphere at an altitude of about 95 km for a region centered at 38°N, 290°E. The measurements show seasonal variation with a high degree of repeatability with peaks in ozone concentration about a month following each equinox. A significant increase in ozone concentration above the yearly trend occurred in 2010 from mid-November until the end of December, which the authors attribute to delay in the start of the meridional circulation …
Accuracy Of The Thin-Lens Approximation In Strong Lensing By Smoothly Truncated Dark Matter Haloes, S. Frittelli, Thomas Kling
Accuracy Of The Thin-Lens Approximation In Strong Lensing By Smoothly Truncated Dark Matter Haloes, S. Frittelli, Thomas Kling
Physics Faculty Publications
The accuracy of mass estimates by gravitational lensing using the thin-lens approximation applied to Navarro–Frenk–White mass models with a soft truncation mechanism recently proposed by Baltz, Marshall and Oguri is studied. The gravitational lens scenario considered is the case of the inference of lens mass from the observation of Einstein rings (strong lensing). It is found that the mass error incurred by the simplifying assumption of thin lenses is below 0.5 per cent. As a byproduct, the optimal tidal radius of the soft truncation mechanism is found to be at most 10 times the virial radius of the mass model.
Demonstrating The Principles Of Aperture Synthesis With The Very Small Radio Telescope, Jonathan M. Marr, Karel Durkota, Francis P. Wilkin, Adam Pere, Alan E.E. Rogers, Vincent L. Fish, Gabriel Holodak, Martina B. Arndt
Demonstrating The Principles Of Aperture Synthesis With The Very Small Radio Telescope, Jonathan M. Marr, Karel Durkota, Francis P. Wilkin, Adam Pere, Alan E.E. Rogers, Vincent L. Fish, Gabriel Holodak, Martina B. Arndt
Physics Faculty Publications
We have developed a set of college-level, table-top labs for teaching the basics of radio interferometry and aperture synthesis. These labs are performed with the Very Small Radio Telescope (VSRT), an interferometer using satellite TV electronics as detectors and compact fluorescent light bulbs as microwave signal sources. The hands-on experience provided by the VSRT in these labs allows students to gain a conceptual understanding of radio interferometry and aperture synthesis without the rigorous mathematical background traditionally required.
Thermodynamics Of The Solar Corona And Evolution Of The Solar Magnetic Field As Inferred From The Total Solar Eclipse Observations Of 2010 July 11, Shadia Rifai Habbal, Miloslav Druckmüller, Huw Morgan, Adalbert Ding, Judd Johnson, Hana Druckmüllerová, Adrian Daw, Martina B. Arndt, Martin Dietzel, Jon Saken
Thermodynamics Of The Solar Corona And Evolution Of The Solar Magnetic Field As Inferred From The Total Solar Eclipse Observations Of 2010 July 11, Shadia Rifai Habbal, Miloslav Druckmüller, Huw Morgan, Adalbert Ding, Judd Johnson, Hana Druckmüllerová, Adrian Daw, Martina B. Arndt, Martin Dietzel, Jon Saken
Physics Faculty Publications
We report on the first multi-wavelength coronal observations, taken simultaneously in white light, Hα 656.3 nm, Fe IX 435.9 nm, Fe X 637.4 nm, Fe XI 789.2 nm, Fe XIII 1074.7 nm, Fe XIV 530.3 nm, and Ni XV 670.2 nm, during the total solar eclipse of 2010 July 11 from the atoll of Tatakoto in French Polynesia. The data enabled temperature differentiations as low as 0.2 × 106 K. The first-ever images of the corona in Fe IX and Ni XV showed that there was very little plasma below 5 × 105 K and above 2.5 × …
Mapping The Distribution Of Electron Temperature And Fe Charge States In The Corona With Total Solar Eclipse Observations, Shadia Rifai Habbal, Miloslav Druckmüller, Huw Morgan, Adrian Daw, Judd Johnson, A. Ding, Martina Arndt, R. Esser, V. Rusin, I. Scholl
Mapping The Distribution Of Electron Temperature And Fe Charge States In The Corona With Total Solar Eclipse Observations, Shadia Rifai Habbal, Miloslav Druckmüller, Huw Morgan, Adrian Daw, Judd Johnson, A. Ding, Martina Arndt, R. Esser, V. Rusin, I. Scholl
Physics Faculty Publications
The inference of electron temperature from the ratio of the intensities of emission lines in the solar corona is valid only when the plasma is collisional. Once collisionless, thermodynamic ionization equilibrium no longer holds, and the inference of an electron temperature and its gradient from such measurements is no longer valid. At the heliocentric distance where the transition from a collision-dominated to a collisionless plasma occurs, the charge states of different elements are established, or frozen-in. These are the charge states which are subsequently measured in interplanetary space. We show in this study how the 2006 March 29 and 2008 …
Total Solar Eclipse Observations Of Hot Prominence Shrouds, Shadia Rifai Habbal, Miloslav Druckmüller, Huw Morgan, I. Scholl, V. Rusin, Adrian Daw, Judd Johnson, Martina B. Arndt
Total Solar Eclipse Observations Of Hot Prominence Shrouds, Shadia Rifai Habbal, Miloslav Druckmüller, Huw Morgan, I. Scholl, V. Rusin, Adrian Daw, Judd Johnson, Martina B. Arndt
Physics Faculty Publications
Using observations of the corona taken during the total solar eclipses of 2006 March 29 and 2008 August 1 in broadband white light and in narrow bandpass filters centered at Fe x 637.4 nm, Fe xi 789.2 nm, Fe xiii 1074.7 nm, and Fe xiv 530.3 nm, we show that prominences observed off the solar limb are enshrouded in hot plasmas within twisted magnetic structures. These shrouds, which are commonly referred to as cavities in the literature, are clearly distinct from the overlying arch-like structures that form the base of streamers. The existence of these hot shrouds had been predicted …
Poisson Equation For Weak Gravitational Lensing, Thomas P. Kling, B. Campbell
Poisson Equation For Weak Gravitational Lensing, Thomas P. Kling, B. Campbell
Physics Faculty Publications
Using the Newman and Penrose [ E. T. Newman and R. Penrose J. Math. Phys. (N.Y.) 3 566 (1962)] spin-coefficient formalism, we examine the full Bianchi identities of general relativity in the context of gravitational lensing, where the matter and space-time curvature are projected into a lens plane perpendicular to the line of sight. From one component of the Bianchi identity, we provide a rigorous, new derivation of a Poisson equation for the projected matter density where the source term involves second derivatives of the observed weak gravitational lensing shear. We also show that the other components of the Bianchi …
Ionization In Fast Atom-Atom Collisions: The Influence And Scaling Behavior Of Electron-Electron And Electron-Nucleus Interactions, J. M. Sanders, R. D. Dubois, S. T. Manson, S. Datz, Edward Deveney, H. F. Krause, J. L. Shinpaugh, C. R. Vane
Ionization In Fast Atom-Atom Collisions: The Influence And Scaling Behavior Of Electron-Electron And Electron-Nucleus Interactions, J. M. Sanders, R. D. Dubois, S. T. Manson, S. Datz, Edward Deveney, H. F. Krause, J. L. Shinpaugh, C. R. Vane
Physics Faculty Publications
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 …
Search For Exchange-Antisymmetric Two-Photon States, D. Demille, D. Budker, N. Derr, Edward Deveney
Search For Exchange-Antisymmetric Two-Photon States, D. Demille, D. Budker, N. Derr, Edward Deveney
Physics Faculty Publications
Atomic two-photon J = 0↔J′ = 1 transitions are forbidden for photons of the same energy. This selection rule is related to the fact that photons obey Bose-Einstein statistics. We have searched for small violations of this selection rule by studying transitions in atomic Ba. We set a limit on the probability v that photons are in exchange-antisymmetric states: v<1.2×10-7.