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Articles 1 - 30 of 60
Full-Text Articles in Physical Sciences and Mathematics
Homonuclear Ultracold Elastic S-Wave Collisions Of Alkali-Metal Atoms Via Multichannel Quantum Defect Theory, Alyson T. Laskowski, Nirav P. Mehta
Homonuclear Ultracold Elastic S-Wave Collisions Of Alkali-Metal Atoms Via Multichannel Quantum Defect Theory, Alyson T. Laskowski, Nirav P. Mehta
Physics and Astronomy Faculty Research
Multichannel quantum-defect theory (MQDT) provides a powerful toolkit for describing and understanding collisions of cold alkali-metal atoms. Various MQDT approximations differ primarily in how they characterize the so-called short-ranged K matrix Ksr, which encapsulates the short-ranged physics into a handful of low-energy parameters that exhibit simple and smooth dependence on energy and field. Here, we compare three different methods for computing Ksr for homonuclear collisions of alkali-metal atoms, from lithium to cesium. The MQDT calculations are benchmarked against numerically converged coupled-channels calculations that use a log-derivative propagator out to the asymptotic region. We study how well these …
Supporting Neurodivergent Talent: Adhd, Autism, And Dyslexia In Physics And Space Sciences, Niescja E. Turner, Heather Haynes Smith
Supporting Neurodivergent Talent: Adhd, Autism, And Dyslexia In Physics And Space Sciences, Niescja E. Turner, Heather Haynes Smith
Physics and Astronomy Faculty Research
Diversity, equity, inclusion, and belonging efforts must include disability and neurodivergence. While there is a long history of famous scientists being identified or speculatively indicated to be neurodivergent, identification on an individual basis has been limited until fairly recently. Definitions have changed and broadened, and people are being identified or are identifying themselves as neurodivergent and are learning about their paths and their brains in a way that was unavailable to people two decades ago. In the contemporary physics or space science classroom or workplace, we have both a responsibility to include and support our neurodivergent learners and scientists, as …
The Importance Of Recruitment And Retention In Heliophysics: It's Not Just A Pipeline Problem, A. J. Halford, C. M. Bard, A. G. Burrell, R. M. Mcgranaghan, L. B. Wilson Iii, M. Jones Jr, C. Dong, L. Wang, T. I. Pulkkinen, Niescja E. Turner, M. W. Liemohn, J. Klenzing
The Importance Of Recruitment And Retention In Heliophysics: It's Not Just A Pipeline Problem, A. J. Halford, C. M. Bard, A. G. Burrell, R. M. Mcgranaghan, L. B. Wilson Iii, M. Jones Jr, C. Dong, L. Wang, T. I. Pulkkinen, Niescja E. Turner, M. W. Liemohn, J. Klenzing
Physics and Astronomy Faculty Research
A major obstacle in cultivating a robust Heliophysics (and broader scientific) community is the lack of diversity throughout science, technology, engineering, and mathematics (STEM) fields. For many years, this has been understood as a “leaky pipeline” analogy, in which predominately minority students initially interested in STEM gradually fall (or are pushed) out of the field on their way to a scientific research position. However, this ignores critical structural and policy issues which drive even later career Ph.D.s out of a career in Heliophysics. We identify here several systemic problems that inhibit many from participating fully in the Heliophysics community, including …
Design And Synthesis Of New Acyl Urea Analogs As Potential Σ1r Selective Ligands, R. Thapa, R. Flores, Kwan H. Cheng, Bereket Mochona, Donald Sikazwe
Design And Synthesis Of New Acyl Urea Analogs As Potential Σ1r Selective Ligands, R. Thapa, R. Flores, Kwan H. Cheng, Bereket Mochona, Donald Sikazwe
Physics and Astronomy Faculty Research
In search of synthetically accessible open-chain analogs of PD144418 or 5-(1-propyl-1,2,5,6-tetrahydropyridin-3-yl)-3-(p-tolyl)isoxazole, a highly potent sigma-1 receptor (σ1R) ligand, we herein report the design and synthesis of sixteen arylated acyl urea derivatives. Design aspects included modeling the target compounds for drug-likeness, docking at σ1R crystal structure 5HK1, and contrasting the lower energy molecular conformers with that of the receptor-embedded PD144418—a molecule we opined that our compounds could mimic pharmacologically. Synthesis of our acyl urea target compounds was achieved in two facile steps which involved first generating the N-(phenoxycarbonyl) benzamide intermediate and then coupling it with the appropriate amines—weakly to strongly …
Cultivating A Culture Of Inclusivity In Heliophysics, A. J. Halford, A. G. Burrell, M. W. Liemohn, M. Jones Jr, A. Maute, T. I. Pulkkinen, C. M. Bard, R. M. Mcgranaghan, L. B. Wilson Iii, R. C. Allen, C. Dong, S. K. Vines, L. Wang, Niescja E. Turner, K. Garcia-Sage, K. Mandt, J. Klenzing
Cultivating A Culture Of Inclusivity In Heliophysics, A. J. Halford, A. G. Burrell, M. W. Liemohn, M. Jones Jr, A. Maute, T. I. Pulkkinen, C. M. Bard, R. M. Mcgranaghan, L. B. Wilson Iii, R. C. Allen, C. Dong, S. K. Vines, L. Wang, Niescja E. Turner, K. Garcia-Sage, K. Mandt, J. Klenzing
Physics and Astronomy Faculty Research
A large number of heliophysicists from across career levels, institution types, and job titles came together to support a poster at Heliophysics 2050 and the position papers for the 2024 Heliophysics decadal survey titled “Cultivating a Culture of Inclusivity in Heliophysics,” “The Importance of Policies: It’s not just a pipeline problem,” and “Mentorship within Heliophysics.” While writing these position papers, the number of people who privately shared disturbing stories and experiences of bullying and harassment was shocking. The number of people who privately expressed how burned out they were was staggering. The number of people who privately spoke about how …
Exploring Membrane Binding Targets Of Disordered Human Tau Aggregates On Lipid Rafts Using Multiscale Molecular Dynamics Simulations, Kwan H. Cheng, Angela Graf, Amber Lewis, Thuong Pham, Aakriti Acharya
Exploring Membrane Binding Targets Of Disordered Human Tau Aggregates On Lipid Rafts Using Multiscale Molecular Dynamics Simulations, Kwan H. Cheng, Angela Graf, Amber Lewis, Thuong Pham, Aakriti Acharya
Physics and Astronomy Faculty Research
The self-aggregation of tau, a microtubule-binding protein, has been linked to the onset of Alzheimer’s Disease. Recent studies indicate that the disordered tau aggregates, or oligomers, are more toxic than the ordered fibrils found in the intracellular neurofibrillary tangles of tau. At present, details of tau oligomer interactions with lipid rafts, a model of neuronal membranes, are not known. Using molecular dynamics simulations, the lipid-binding events, membrane-damage, and protein folding of tau oligomers on various lipid raft surfaces were investigated. Tau oligomers preferred to bind to the boundary domains (Lod) created by the coexisting liquid-ordered (Lo) and liquid-disordered (Ld) domains …
Seven Years Of Sn 2014c: A Multiwavelength Synthesis Of An Extraordinary Supernova, B. P. Thomas, J. C. Wheeler, V. V. Dwarkadas, C. Stockdale, J. Vinkó, David Pooley, Y. Xu, G. Zeimann, P. Macqueen
Seven Years Of Sn 2014c: A Multiwavelength Synthesis Of An Extraordinary Supernova, B. P. Thomas, J. C. Wheeler, V. V. Dwarkadas, C. Stockdale, J. Vinkó, David Pooley, Y. Xu, G. Zeimann, P. Macqueen
Physics and Astronomy Faculty Research
SN 2014C was originally classified as a Type Ib supernova, but at phase ϕ = 127 days, post-explosion strong Hα emission was observed. SN 2014C has since been observed in radio, infrared, optical and X-ray bands. Here we present new optical spectroscopic and photometric data spanning ϕ = 947–2494 days post-explosion. We address the evolution of the broadened Hα emission line, as well as broad [O iii] emission and other lines. We also conduct a parallel analysis of all publicly available multiwavelength data. From our spectra, we find a nearly constant Hα FWHM velocity width of ∼2000 …
Using Experimentally Calibrated Regularized Stokeslets To Assess Bacterial Flagellar Motility Near A Surface, Orrin Shindell, Hoa Nguyen, Nicholas Coltharp, Frank G. Healy, B. Rodenborn
Using Experimentally Calibrated Regularized Stokeslets To Assess Bacterial Flagellar Motility Near A Surface, Orrin Shindell, Hoa Nguyen, Nicholas Coltharp, Frank G. Healy, B. Rodenborn
Physics and Astronomy Faculty Research
The presence of a nearby boundary is likely to be important in the life cycle and evolution of motile flagellate bacteria. This has led many authors to employ numerical simulations to model near-surface bacterial motion and compute hydrodynamic boundary effects. A common choice has been the method of images for regularized Stokeslets (MIRS); however, the method requires discretization sizes and regularization parameters that are not specified by any theory. To determine appropriate regularization parameters for given discretization choices in MIRS, we conducted dynamically similar macroscopic experiments and fit the simulations to the data. In the experiments, we measured the torque …
Scattering Of Two Particles In A One-Dimensional Lattice, Seth T. Rittenhouse, P. Giannakeas, Nirav P. Mehta
Scattering Of Two Particles In A One-Dimensional Lattice, Seth T. Rittenhouse, P. Giannakeas, Nirav P. Mehta
Physics and Astronomy Faculty Research
This study concerns the two-body scattering of particles in a one-dimensional periodic potential. A convenient ansatz allows for the separation of center-of-mass and relative motion, leading to a discrete Schrödinger equation in the relative motion that resembles a tight-binding model. A lattice Green's function is used to develop the Lippmann-Schwinger equation, and ultimately derive a multiband scattering Κ matrix which is described in detail in the two-band approximation. Two distinct scattering lengths are defined according to the limits of zero relative quasimomentum at the top and bottom edges of the two-body collision band. Scattering resonances occur in the collision band …
Coarse-Grained Md Simulations Reveal Beta-Amyloid Fibrils Of Various Sizes Bind To Interfacial Liquid-Ordered And Liquid-Disordered Regions In Phase Separated Lipid Rafts With Diverse Membrane-Bound Conformational States, S. Y. Cheng, Yiyi Cao, Marzieh Rouzbehani, Kwan H. Cheng
Coarse-Grained Md Simulations Reveal Beta-Amyloid Fibrils Of Various Sizes Bind To Interfacial Liquid-Ordered And Liquid-Disordered Regions In Phase Separated Lipid Rafts With Diverse Membrane-Bound Conformational States, S. Y. Cheng, Yiyi Cao, Marzieh Rouzbehani, Kwan H. Cheng
Physics and Astronomy Faculty Research
The membrane binding behaviors of beta-amyloid fibrils, dimers to pentamers, from solution to lipid raft surfaces, were investigated using coarse-grained (CG) MD simulations. Our CG rafts contain phospholipid, cholesterol (with or without tail- or headgroup modifications), and with or without asymmetrically distributed monosialotetrahexosylganglioside (GM1). All rafts exhibited liquid-ordered (Lo), liquid-disordered (Ld), and interfacial Lo/Ld (Lod) domains, with domain sizes depending on cholesterol structure. For rafts without GM1, all fibrils bound to the Lod domains. Specifically, dimer fibrils bound exclusively via the C-terminal, while larger fibrils could bind via other protein regions. Interestingly, a membrane-inserted state was detected for a trimer …
Ligo Analogy Lab—A Set Of Undergraduate Lab Experiments To Demonstrate Some Principles Of Gravitational Wave Detection, Dennis Ugolini, Hanna Rafferty, M. Winter, C. Rockstuhl, A. Bergmann
Ligo Analogy Lab—A Set Of Undergraduate Lab Experiments To Demonstrate Some Principles Of Gravitational Wave Detection, Dennis Ugolini, Hanna Rafferty, M. Winter, C. Rockstuhl, A. Bergmann
Physics and Astronomy Faculty Research
The first direct detection of gravitational waves by the Laser Interferometer Gravitational-Wave Observatory (LIGO) in September 2015 proved their existence, as predicted by Einstein's General Theory of Relativity, and ushered in the era of gravitational-wave interferometry. In this article, we present a set of lab course experiments at different levels of advancement, which give students insight into the basic LIGO operating principle and advanced detection techniques. Starting with methods for folding an optical cavity, we advance to analogy experiments with sound waves that can be detected with a Michelson interferometer with an optical cavity arm. In that experiment, students also …
Model For Scattering With Proliferating Resonances: Many Coupled Square Wells, Nirav P. Mehta, Kaden R. A Hazzard, Christopher Ticknor
Model For Scattering With Proliferating Resonances: Many Coupled Square Wells, Nirav P. Mehta, Kaden R. A Hazzard, Christopher Ticknor
Physics and Astronomy Faculty Research
We present a multichannel model for elastic interactions, composed of an arbitrary number of coupled finite square-well potentials, and derive semianalytic solutions for its scattering behavior. Despite the model's simplicity, it is flexible enough to include many coupled short-ranged resonances in the vicinity of the collision threshold, as is necessary to describe ongoing experiments in ultracold molecules and lanthanide atoms. We also introduce a simple but physically realistic statistical ensemble for parameters in this model. We compute the resulting probability distributions of nearest-neighbor resonance spacings and analyze them by fitting to the Brody distribution. We quantify the ability of alternative …
X-Ray Swift Observations Of Sn 2018cow, L E. Rivera Sandoval, T J. Maccarone, A Corsi, P J. Brown, David Pooley, J C. Wheeler
X-Ray Swift Observations Of Sn 2018cow, L E. Rivera Sandoval, T J. Maccarone, A Corsi, P J. Brown, David Pooley, J C. Wheeler
Physics and Astronomy Faculty Research
Supernova (SN) 2018cow is an optical transient detected in the galaxy CGCG 137–068. It has been classified as a SN due to various characteristics in its optical spectra. The transient is also a bright X-ray source. We present results of the analysis of ∼ 62 ks of X-ray observations taken with the Neil Gehrels Swift Observatory over 27 days. We found a variable behavior in the 0 . 3 − 10 keV X-ray light curve of SN 2018cow, with variability timescales of days. The observed X-ray variability could be due to the interaction between the SN ejecta and a non-uniform …
4,5-Dimethoxy-2-Nitrobenzohydrazides And 1-(1-Benzylpiperidin-4-Yl)Ethan-1-Ones As Potential Antioxidant/Cholinergic Endowed Small Molecule Leads, Rukhsar Banu, Jason Gerding, Cynthia Franklin, Donald Sikazwe, William Horton, Marianna Török, Julian Davis, Kwan H. Cheng, Muziya Nakazwe, Bereket Mochona
4,5-Dimethoxy-2-Nitrobenzohydrazides And 1-(1-Benzylpiperidin-4-Yl)Ethan-1-Ones As Potential Antioxidant/Cholinergic Endowed Small Molecule Leads, Rukhsar Banu, Jason Gerding, Cynthia Franklin, Donald Sikazwe, William Horton, Marianna Török, Julian Davis, Kwan H. Cheng, Muziya Nakazwe, Bereket Mochona
Physics and Astronomy Faculty Research
The objective of this research is to generate leads for developing our ultimate poly-active molecules with utility in central nervous system (CNS) diseases. Indeed, poly-active molecules capable of mitigating brain free radical damage while enhancing acetylcholine signaling (via cholinesterase inhibition) are still being sought for combating Alzheimer’s disease (AD). We differentiate “poly-active” agents from “multi-target” ones by defining them as single molecular entities designed to target only specific contributory synergistic pharmacologies in a disease. For instance, in AD, free radicals either initiate or act in synergy with other pharmacologies, leading to disease worsening. For this preliminary report, a total of …
An Active Galactic Nucleus Caught In The Act Of Turning Off And On, Julia M. Comerford, R Scott Barrows, Francisco Müller Sánchez, Rebecca Nevin, Jenny E. Greene, David Pooley, Daniel Stern, Fiona A. Harrison
An Active Galactic Nucleus Caught In The Act Of Turning Off And On, Julia M. Comerford, R Scott Barrows, Francisco Müller Sánchez, Rebecca Nevin, Jenny E. Greene, David Pooley, Daniel Stern, Fiona A. Harrison
Physics and Astronomy Faculty Research
We present the discovery of an active galactic nucleus (AGN) that is turning off and then on again in the z = 0.06 galaxy SDSS J1354+1327. This episodic nuclear activity is the result of discrete accretion events that could have been triggered by a past interaction with the companion galaxy that is currently located 12.5 kpc away. We originally targeted SDSS J1354+1327 because its Sloan Digital Sky Survey spectrum has narrow AGN emission lines that exhibit a velocity offset of 69 km s−1 relative to systemic. To determine the nature of the galaxy and its velocity-offset emission lines, we …
Microscopic Derivation Of Multichannel Hubbard Models For Ultracold Nonreactive Molecules In An Optical Lattice, Michael L. Wall, Nirav P. Mehta, Rick Mukherjee, Shah Saad Alam, Kaden R. A Hazzard
Microscopic Derivation Of Multichannel Hubbard Models For Ultracold Nonreactive Molecules In An Optical Lattice, Michael L. Wall, Nirav P. Mehta, Rick Mukherjee, Shah Saad Alam, Kaden R. A Hazzard
Physics and Astronomy Faculty Research
Recent experimental advances in the cooling and manipulation of bialkali-metal dimer molecules have enabled the production of gases of ultracold molecules that are not chemically reactive. It has been presumed in the literature that in the absence of an electric field the low-energy scattering of such nonreactive molecules (NRMs) will be similar to atoms, in which a single s-wave scattering length governs the collisional physics. However, Doçaj et al. [Phys. Rev. Lett. 116, 135301 (2016)] argued that the short-range collisional physics of NRMs is much more complex than for atoms and that this leads to a many-body description …
Lattice-Model Parameters For Ultracold Nonreactive Molecules: Chaotic Scattering And Its Limitations, Michael L. Wall, Rick Mukherjee, Shah Saad Alam, Nirav P. Mehta, Kaden R. A Hazzard
Lattice-Model Parameters For Ultracold Nonreactive Molecules: Chaotic Scattering And Its Limitations, Michael L. Wall, Rick Mukherjee, Shah Saad Alam, Nirav P. Mehta, Kaden R. A Hazzard
Physics and Astronomy Faculty Research
We calculate the parameters of the recently derived many-channel Hubbard model that is predicted to describe ultracold nonreactive molecules in an optical lattice, going beyond the approximations used by Doçaj et al. [A. Doçaj et al., Phys. Rev. Lett. 116, 135301 (2016)]. Although those approximations are expected to capture the qualitative structure of the model parameters, finer details and quantitative values are less certain. To set expectations for experiments, whose results depend on the model parameters, we describe the approximations’ regime of validity and the likelihood that experiments will be in this regime, discuss the impact that the …
Spatially Offset Active Galactic Nuclei. Ii. Triggering In Galaxy Mergers, R Scott Barrows, Julia M. Comerford, Jenny E. Greene, David Pooley
Spatially Offset Active Galactic Nuclei. Ii. Triggering In Galaxy Mergers, R Scott Barrows, Julia M. Comerford, Jenny E. Greene, David Pooley
Physics and Astronomy Faculty Research
Galaxy mergers are likely to play a role in triggering active galactic nuclei (AGNs), but the conditions under which this process occurs are poorly understood. In Paper I, we constructed a sample of spatially offset X-ray AGNs that represent galaxy mergers hosting a single AGN. In this paper, we use our offset AGN sample to constrain the parameters that affect AGN observability in galaxy mergers. We also construct dual-AGN samples with similar selection properties for comparison. We find that the offset AGN fraction shows no evidence for a dependence on AGN luminosity, while the dual-AGN fractions show stronger evidence for …
Temperature Of The Plasmasphere From Van Allen Probes Hope, Kevin J. Genestreti, Jerry Goldstein, Grace D. Corley, William Farner, Lynn M. Kistler, Brian A. Larsen, Christopher G. Mouikis, Chae Ramnarace, Ruth M. Skoug, Niescja E. Turner
Temperature Of The Plasmasphere From Van Allen Probes Hope, Kevin J. Genestreti, Jerry Goldstein, Grace D. Corley, William Farner, Lynn M. Kistler, Brian A. Larsen, Christopher G. Mouikis, Chae Ramnarace, Ruth M. Skoug, Niescja E. Turner
Physics and Astronomy Faculty Research
We introduce two novel techniques for estimating temperatures of very low energy space plasmas using, primarily, in situ data from an electrostatic analyzer mounted on a charged and moving spacecraft. The techniques are used to estimate proton temperatures during intervals where the bulk of the ion plasma is well below the energy bandpass of the analyzer. Both techniques assume that the plasma may be described by a one-dimensional E→×B→ drifting Maxwellian and that the potential field and motion of the spacecraft may be accounted for in the simplest possible manner, i.e., by a linear shift of coordinates. The first technique …
Few-Boson Processes In The Presence Of An Attractive Impurity Under One-Dimensional Confinement, Nirav P. Mehta, Connor D. Morehead
Few-Boson Processes In The Presence Of An Attractive Impurity Under One-Dimensional Confinement, Nirav P. Mehta, Connor D. Morehead
Physics and Astronomy Faculty Research
We consider a few-boson system confined to one dimension with a single distinguishable particle of lesser mass. All particle interactions are modeled with δ functions, but due to the mass imbalance the problem is nonintegrable. Universal few-body binding energies, atom-dimer and atom-trimer scattering lengths, are all calculated in terms of two parameters, namely the mass ratio mL/mH, and ratio gHH/gHL of the δ-function couplings. We specifically identify the values of these ratios for which the atom-dimer or atom-trimer scattering lengths vanish or diverge. We identify regions in this parameter space …
Characterization Of 3d Voronoi Tessellation Nearest Neighbor Lipid Shells Provides Atomistic Lipid Disruption Profile Of Protein Containing Lipid Membranes, Sara Y. Cheng, Hai Viet Duong, Campbell Compton, Mark W. Vaughn, Hoa Nguyen, Kwan H. Cheng
Characterization Of 3d Voronoi Tessellation Nearest Neighbor Lipid Shells Provides Atomistic Lipid Disruption Profile Of Protein Containing Lipid Membranes, Sara Y. Cheng, Hai Viet Duong, Campbell Compton, Mark W. Vaughn, Hoa Nguyen, Kwan H. Cheng
Physics and Astronomy Faculty Research
Quantifying protein-induced lipid disruptions at the atomistic level is a challenging problem in membrane biophysics. Here we propose a novel 3D Voronoi tessellation nearest-atom-neighbor shell method to classify and characterize lipid domains into discrete concentric lipid shells surrounding membrane proteins in structurally heterogeneous lipid membranes. This method needs only the coordinates of the system and is independent of force fields and simulation conditions. As a proof-of-principle, we use this multiple lipid shell method to analyze the lipid disruption profiles of three simulated membrane systems: phosphatidylcholine, phosphatidylcholine/cholesterol, and beta-amyloid/phosphatidylcholine/cholesterol. We observed different atomic volume disruption mechanisms due to cholesterol and beta-amyloid. …
Scaling And Alpha-Helix Regulation Of Protein Relaxation In A Lipid Bilayer, Liming Qiu, Creighton Buie, Kwan H. Cheng, Mark W. Vaughn
Scaling And Alpha-Helix Regulation Of Protein Relaxation In A Lipid Bilayer, Liming Qiu, Creighton Buie, Kwan H. Cheng, Mark W. Vaughn
Physics and Astronomy Faculty Research
Protein conformation and orientation in the lipid membrane plays a key role in many cellular processes. Here we use molecular dynamics simulation to investigate the relaxation and C-terminus diffusion of a model helical peptide: beta-amyloid (Aβ) in a lipid membrane.We observed that after the helical peptide was initially half-embedded in the extracelluar leaflet of phosphatidylcholine (PC) or PC/cholesterol (PC/CHOL) membrane, the C-terminus diffused across the membrane and anchored to PC headgroups of the cytofacial lipid leaflet. In some cases, the membrane insertion domain of the Aβ was observed to partially unfold. Applying a sigmoidal fit to the process, we found …
Experiments On Tracer Diffusion In Aqueous And Non-Aqueous Solvent Combinations, Duncan M. Frasch, Daniel Spiegel
Experiments On Tracer Diffusion In Aqueous And Non-Aqueous Solvent Combinations, Duncan M. Frasch, Daniel Spiegel
Physics and Astronomy Faculty Research
Forced Rayleigh scattering is used to study the tracer diffusion of an azobenzene in binary combinations of polar solvents, including water. In the absence of water, the tracer diffusion coefficient D in the mixture lies between the diffusion coefficients within the pure solvents, on a curve that is reasonably close to the prediction of free-volume theory. If water is present, on the other hand, the diffusion coefficient displays a minimum that is less than the smaller of the two pure-solvent values. We attempt to understand the different behavior in water by concentrating on the fairly hydrophobic nature of the solute, …
Born-Oppenheimer Study Of Two-Component Few-Particle Systems Under One-Dimensional Confinement, Nirav P. Mehta
Born-Oppenheimer Study Of Two-Component Few-Particle Systems Under One-Dimensional Confinement, Nirav P. Mehta
Physics and Astronomy Faculty Research
The energy spectrum, atom-dimer scattering length, and atom-trimer scattering length for systems of three and four ultracold atoms with δ-function interactions in one dimension are presented as a function of the relative mass ratio of the interacting atoms. The Born-Oppenheimer approach is used to treat three-body (“HHL”) systems of one light and two heavy atoms, as well as four-body (“HHHL”) systems of one light and three heavy atoms. Zero-range interactions of arbitrary strength are assumed between different atoms, but the heavy atoms are assumed to be noninteracting among themselves. Fermionic and bosonic heavy atoms with both positive and negative parity …
Experimental Tests Of Free-Volume Tracer Diffusion In Water And Other Solvents, Daniel Spiegel, Paulses C. Kollie, Scott J. Van Tilburg
Experimental Tests Of Free-Volume Tracer Diffusion In Water And Other Solvents, Daniel Spiegel, Paulses C. Kollie, Scott J. Van Tilburg
Physics and Astronomy Faculty Research
Using forced Rayleigh scattering, the tracer diffusion of methyl red through water and eight other solvents at different temperatures is investigated and the results are compared to the Cohen-Turnbull theory of free-volume diffusion. In seven solvents the effective non-Arrhenius activation energy measured experimentally agrees with the Cohen-Turnbull energy. In water, however, the diffusion can be described mathematically by the free volume model but there is a disagreement of more than an order of magnitude between these energies. We propose that the unique "zero point" free volume forced onto water by the strong hydrogen bonding requires a different mechanism for tracer …
Comparative Analysis Of A Transition Region Bright Point With A Blinker And Coronal Bright Point Using Multiple Eis Emission Lines, N B. Orange, H M. Oluseyi, D L. Chesny, M Patel, K Hesterly, L Preuss, C Neira, Niescja E. Turner
Comparative Analysis Of A Transition Region Bright Point With A Blinker And Coronal Bright Point Using Multiple Eis Emission Lines, N B. Orange, H M. Oluseyi, D L. Chesny, M Patel, K Hesterly, L Preuss, C Neira, Niescja E. Turner
Physics and Astronomy Faculty Research
Since their discovery 20 year ago, transition region bright points have never been observed spectroscopically. Bright point properties have not been compared with similar transition region and coronal structures. In this work we have investigated three transient quiet Sun brightenings including a transition region bright point (TR BP), a coronal bright point (CBP) and a blinker. We use time-series observations of the extreme-ultraviolet emission lines of a wide range of temperature T(logT=5.3 – 6.4) from the EUV Imaging Spectrometer (EIS) onboard the Hinode satellite. We present the EIS temperature maps and Doppler maps, which are compared with …
Effects Of Different Geomagnetic Storm Drivers On The Ring Current: Crcm Results, W D. Cramer, Niescja E. Turner, M C. Fok, N Y. Buzulukova
Effects Of Different Geomagnetic Storm Drivers On The Ring Current: Crcm Results, W D. Cramer, Niescja E. Turner, M C. Fok, N Y. Buzulukova
Physics and Astronomy Faculty Research
The storm-time magnetic disturbance at the Earth's equator, as commonly measured by the Dst index, is induced by currents in the near-Earth magnetosphere. The ring current is generally considered the most important contributor, but other magnetospheric currents have also been found to have significant effects. Of the two main types of solar geomagnetic storm drivers, Coronal Mass Ejections (CMEs) tend to have a much greater impact on Dst than Corotating Interaction Regions (CIRs). Ring current models have been found to underestimate Dst, particularly during storms driven by CIRs. One possible explanation is that the models neglect to handle some aspect …
Florida Energy Assurance Plan, Niescja E. Turner, W Murtagh, K Guthrie, K Nykyri, W A. Radasky, E Senkowicz
Florida Energy Assurance Plan, Niescja E. Turner, W Murtagh, K Guthrie, K Nykyri, W A. Radasky, E Senkowicz
Physics and Astronomy Faculty Research
This spring, Florida held the nations first statewide emergency preparedness training and exercises geared specifically to the aftermath of severe geomagnetic events. Funded by the State of Florida Division of Emergency Management (FDEM) via a Department of Energy grant and held in collaboration with Watch House International, Inquesta Corporation, and the Florida Institute of Technology, the 17-19 April 2012 workshop had 99 on-site attendees in an oceanfront hotel in Melbourne, Florida, as well as 16 over live Web streaming. The workshop was the capstone to a three-month season of 21 regional space weather training sessions and workshops serving 386 attendees …
Calorimetric Behavior Of Phosphatidylcholine/Phosphatidylethanolamine Bilayers Is Compatible With The Superlattice Model, Kwan H. Cheng, Jorma Virtanen, Pentti Somerharju
Calorimetric Behavior Of Phosphatidylcholine/Phosphatidylethanolamine Bilayers Is Compatible With The Superlattice Model, Kwan H. Cheng, Jorma Virtanen, Pentti Somerharju
Physics and Astronomy Faculty Research
Differential scanning calorimetry was used to study the phase behavior of binary lipid bilayers consisting of phosphatidylcholine (PC) and phosphatidylethanolamine (PE) of varying acyl chain length. A two-state transition model was used to resolve the individual transition components, and the two-state transition enthalpy, the relative enthalpy, and the transition temperature of each component were plotted as a function of composition. Intriguingly, abrupt changes in these thermodynamic parameters were observed at or close to many “critical” XPE values predicted by the superlattice model proposing that phospholipids with different headgroups tend to adopt regular rather than random lateral distributions. Statistical analysis …
The Hyperspherical Four-Fermion Problem, Seth T. Rittenhouse, J Von Stecher, J P. D'Incao, Nirav P. Mehta, Chris H. Greene
The Hyperspherical Four-Fermion Problem, Seth T. Rittenhouse, J Von Stecher, J P. D'Incao, Nirav P. Mehta, Chris H. Greene
Physics and Astronomy Faculty Research
The problem of a few interacting fermions in quantum physics has sparked intense interest, particularly in recent years owing to connections with the behaviour of superconductors, fermionic superfluids and finite nuclei. This review addresses recent developments in the theoretical description of four fermions having finite-range interactions, stressing insights that have emerged from a hyperspherical coordinate perspective. The subject is complicated, so we have included many detailed formulae that will hopefully make these methods accessible to others interested in using them. The universality regime, where the dominant length scale in the problem is the two-body scattering length, is particularly stressed, including …