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Search Results: 1 - 10 of 401160 matches for " Chelsey M. Crosse "
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tert-Butyl 2-methyl-2-(4-nitrobenzoyl)propanoate
Chelsey M. Crosse,Marshall W. Logue,Rudy L. Luck,Louis R. Pignotti
Acta Crystallographica Section E , 2010, DOI: 10.1107/s1600536810003119
Abstract: The title compound, C15H19NO5, is bent with a dihedral angle of 61.8 (2)° between the mean planes of the benzene ring and a group encompassing the ester functionality (O=C—O—C). The dihedral angle of 0.8 (2)° between the mean planes of the nitro group and the benzene ring indicates near coplanarity. In the crystal, each molecule is linked to four adjacent molecules by weak C—H...O hydrogen-bonding interactions. Both benzene H atoms ortho to the ketone O atom form C—H...O hydrogen bonds with the keto O atoms of two neighboring molecules (of the keto and ester groups, respectively), and the two other interactions involve the H atoms from a methyl group of the dimethyl residue, displaying C—H...O interactions with the O atoms of the nitro groups. These four interactions for each molecule lead to the formation of two-dimensional sheets with a hydrophilic interior, held together by weak hydrogen-bonded interactions, and a hydrophobic exterior composed of protruding methyl groups which interstack with the methyl groups in adjacent sheets.
tert-Butyl 2-(4-chlorobenzoyl)-2-methylpropanoate
Chelsey M. Crosse,Emily C. Kelly,Marshall W. Logue,Rudy L. Luck
Acta Crystallographica Section E , 2010, DOI: 10.1107/s1600536810003156
Abstract: The title compound, C15H19ClO3, is bent with a dihedral angle of 72.02 (9)° between the mean planes of the benzene ring and a group encompassing the ester functionality (O=C—O—C). In the crystal, molecules related by inversion symmetry are connected by weak C—H...O interactions into infinite chains. These interactions involve H atoms from a methyl group of the dimethyl residue and the O atoms of the ketone on one side of a molecule; on the other side there are interactions between H atoms of the benzene ring and the carbonyl O atoms of the ester functionality. There are no directional interactions between the chains.
Embodied health: the effects of a mind–body course for medical students
Allison R. Bond,Heather F. Mason,Chelsey M. Lemaster,Stephanie E. Shaw
Medical Education Online , 2013, DOI: 10.3402/meo.v18i0.20699
Abstract: Objective: An effective career in medicine requires empathy and compassion, yet the demands of a medical education increase stress and decrease students’ ability to connect with patients. However, research suggests mind-body practices improve psychological well-being. This study aimed to evaluate the psychological effects on medical students of an 11-week elective course, Embodied Health or EH, which combines yoga and meditation with neuroscience didactics. Methods: The effects on 27 first- and second-year medical students were evaluated via surveys in four areas: empathy, perceived stress, self-regulation, and self-compassion. Scales used were 1. Jefferson Scale of Physician Empathy, which measures empathy among health students and professionals and medical students on a scale of 1 (least empathetic) to 7 (most empathetic); 2. Cohen's Perceived Stress Scale, a measure of the perceived uncontrollability of respondents' lives, from 0 (least stressed) to 4 (most stressed); 3. Self-Regulation Questionnaire, which measures the development and maintenance of planned behavior to achieve goals, from 1 (least self-regulated) to 5 (most self-regulated); and 4. Self-Compassion Scale, which measures self-criticism, from 1 (least self-compassionate) to 5 (most self-compassionate). Students also reflected on EH's impact on their well-being in a post-course essay. Results: Self-regulation and self-compassion rose 0.13 (SD 0.20, p = 0.003) and 0.28 (SD 0.61, p = 0.04), respectively. Favorable changes were also seen in empathy and perceived stress, which went up by 0.11 (SD 0.50, p = 0.30) and down by 0.05 (SD 0.62, p = 0.70), respectively; these changes did not reach statistical significance. Students’ essays were found to discuss the following recurrent themes: 1) Reconnection between mind and body; 2) Community in a competitive environment; 3) Increased mindfulness; 4) Confidence in use of mind-body skills with patients; and 5) Stress management. These themes overlapped with the measures EH affected quantitatively. Conclusion: A mind-body course for medical students increased self-regulation and self-compassion. Qualitative themes discussed in students’ post-course essays reflected these effects.
Rapamycin weekly maintenance dosing and the potential efficacy of combination sorafenib plus rapamycin but not atorvastatin or doxycycline in tuberous sclerosis preclinical models
Lee Nancy,Woodrum Chelsey L,Nobil Alison M,Rauktys Aubrey E
BMC Pharmacology , 2009, DOI: 10.1186/1471-2210-9-8
Abstract: Background Tuberous sclerosis complex (TSC) is an autosomal dominant tumor suppressor syndrome, characterized by hamartomatous growths in the brain, skin, kidneys, lungs, and heart, which lead to significant morbidity. TSC is caused by mutations in the TSC1 or TSC2 genes, whose products, hamartin and tuberin, form a tumor suppressor complex that regulates the PI3K/Akt/mTOR pathway. Early clinical trials show that TSC-related kidney tumors (angiomyolipomas) regress when treated with the mammalian target of rapamycin (mTOR) inhibitor, rapamycin (also known as sirolimus). Although side effects are tolerable, responses are incomplete, and tumor regrowth is common when rapamycin is stopped. Strategies for future clinical trials may include the investigation of longer treatment duration and combination therapy of other effective drug classes. Results Here, we examine the efficacy of a prolonged maintenance dose of rapamycin in Tsc2+/- mice with TSC-related kidney tumors. Cohorts were treated with rapamycin alone or in combination with interferon-gamma (IFN-g). The schedule of rapamycin included one month of daily doses before and after five months of weekly doses. We observed a 94.5% reduction in kidney tumor burden in Tsc2+/- mice treated (part one) daily with rapamycin (8 mg/kg) at 6 months ≤ age < 7 months, (part 2) weekly with rapamycin (16 mg/kg) at 7 months ≤ age < 12 months, and (part 3) daily with rapamycin (8 mg/kg) at 12 months ≤ age < 13 months; but we did not observe any improvement with combination IFN-g plus rapamycin in this study. We also used a Tsc2-/- subcutaneous tumor model to evaluate other classes of drugs including sorafenib, atorvastatin, and doxycycline. These drugs were tested as single agents and in combination with rapamycin. Our results demonstrate that the combination of rapamycin and sorafenib increased survival and may decrease tumor volume as compared to rapamycin treatment alone while sorafenib as a single agent was no different than control. Atorvastatin and doxycycline, either as single agents or in combination with rapamycin, did not improve outcomes as compared with controls. Conclusion Our results indicate that prolonged treatment with low doses of mTOR inhibitors may result in more complete and durable TSC-related tumor responses, and it would be reasonable to evaluate this strategy in a clinical trial. Targeting the Raf/Mek/Erk and/or VEGF pathways in combination with inhibiting the mTOR pathway may be another useful strategy for the treatment of TSC-related tumors.
Optical Properties of Topological Insulator Bragg Gratings
J. A. Crosse
Physics , 2015,
Abstract: Using the transfer matrix formalism, we study the transmission properties of a Bragg grating constructed from a layered axionic material. Such a material can be realized by a topological insulator subject to a time-symmetry breaking perturbation, such as an external magnetic field or surface magnetic impurities. Whilst the reflective properties of the structure are only negligibly changed by the presence of the axionic material, the grating induces Faraday and Kerr rotations in the transmitted and reflected light, respectively. These rotations are proportional to the number of layers and the strength of the time-symmetry breaking perturbation. In areas of low reflectivity the rotation angle of TE polarization decreases with increasing incidence angle while the TM polarization increases with increasing incidence angle with the converse occurring in areas of high reflectivity. The formalism and results will be useful in the development of optical and photonic devices based on topological insulators, devices which will be especially useful in situations where polarization control is desired.
Theory of topological insulator waveguides: polarization control and the enhancement of the magneto-electric effect
J. A. Crosse
Physics , 2015,
Abstract: Topological insulators subject to a time-symmetry-breaking perturbation are predicted to display a magneto-electric effect that causes the electric and magnetic induction fields to mix at the material's surface. This effect induces polarization rotations of between ~1-10 mrad per interface in incident plane-polarized light normal to a multilayered structure. Here we show, theoretically and numerically, that, using a waveguide geometry with a topological insulator guide layer and dielectric cladding, it is possible to achieve rotations of between ~100-1000 mrad and generate an elliptical polarization with only a three-layered structure. Both the rotation angle and ellipticity are dependent on the permittivity contrast of the guide and cladding layers and the strength of the time-symmetry-breaking perturbation. This geometry is beneficial, not only as a way to enhance the magneto-electric effect, rendering it easier to observe, but also as a method for controlling the polarization of light in the next generation of photonic devices.
Large displacement strain theory and its application to graphene
J. A. Crosse
Physics , 2014, DOI: 10.1103/PhysRevB.90.045201
Abstract: Under the application of a force, a material will deform and, hence, the crystal lattice will experience strain. This induced strain will alter the electronic properties of the material. In particular, strain in graphene generates an artificial vector potential which, if spatially varying, admits a pseudo-magnetic field. Current theories for spatially varying strain use linear or finite strain theory whose derivation is based on small displacements of infinitesimal length vectors. Here we apply a differential geometry method to derive a strain theory for large displacements of finite length vectors. This method gives a finite displacement term whose contribution is comparable to that of the linear strain term. Further to this, we show that a 'domain wall'-like pseudo-magnetic field profile can be generated when a wide graphene ribbon is subjected to a pair of opposing point forces (point stretch). The resulting field is a function of the new finite displacement term only and displays a maximum strength of over three times that which is predicted by the linear strain theory. These results extend the current theories of strain, which are based on the transformation of infinitesimal length vectors, to finite length vectors, thus providing an accurate description of pseudo-magnetic field structures in strained materials.
Strain dependent conductivity in biased bilayer graphene
J. A. Crosse
Physics , 2014, DOI: 10.1103/PhysRevB.90.235403
Abstract: Intrinsic bilayer graphene is a gapless semimetal. Under the application of a bias field it becomes a semiconductor with a direct band gap that is proportional to the applied field. Under a layer-asymmetric strain (where the upper layer undergoes compression and lower layer tension or visa-versa) we find that the band gap of a biased bilayer graphene ribbon becomes indirect and, for higher strains, becomes negative returning the material its original semimetal state. As a result, the conductivity of the ribbon increases and can be almost an order of magnitude larger that of the intrinsic unbiased material - a change that can be induced with a strain of only ~2-3%. The conductivity is proportional to the applied strain and the magnitude of the effect is tunable with the bias field. Such layer-asymmetric strains can be achieved by bending, with forces on the order of ~1nN resulting in a layer-asymmetric strain of ~1%. This new electromechanical effect has a wide potential for application in the areas of nano-force microscopy and pressure sensing on the atomic scale.
The in Vivo Antioxidant Effects of (−)-Epigallocatechin-3-Gallate Consumption in Healthy Postmenopausal Women Measured by Urinary Excretion of Secondary Lipid Peroxidation Products  [PDF]
Chelsey Fiecke, Mindy Kurzer, Chi Chen, A. Saari Csallany
Food and Nutrition Sciences (FNS) , 2019, DOI: 10.4236/fns.2019.101002
Abstract: The present study was carried out to determine whether the consumption of epigallocatechin (EGCG), the major bioactive green tea catechin, exerts a positive effect on lowering in vivo lipid peroxidation, a measure of oxidative stress, in healthy postmenopausal women. Urinary excretion of secondary lipid peroxidation products, a measure of in vivo lipid peroxidation, was determined in 40 participants randomly assigned to consume a green tea catechin extract (843.0 ± 44.0 mg EGCG/d) or placebo capsules for 12 months. Urine samples were analyzed for individual polar and nonpolar lipophilic aldehydes and related carbonyl compounds by high-performance liquid chromatography (HPLC) at the beginning and at the end of the 12-month intervention period. Results show that two nonpolar aldehydes, nonanal and decatrienal, were both 48% lower (p < 0.005) following consumption of EGCG. These results indicate that a modest degree of in vivo antioxidant activity exists with long-term EGCG consumption, which could slightly limit oxidative damage associated with lipid peroxidation and the onset and progression of chronic diseases.
Atomic multipole relaxation rates near surfaces
J. A. Crosse,Stefan Scheel
Physics , 2009, DOI: 10.1103/PhysRevA.79.062902
Abstract: The spontaneous relaxation rates for an atom in free space and close to an absorbing surface are calculated to various orders of the electromagnetic multipole expansion. The spontaneous decay rates for dipole, quadrupole and octupole transitions are calculated in terms of their respective primitive electric multipole moments and the magnetic relaxation rate is calculated for the dipole and quadrupole transitions in terms of their respective primitive magnetic multipole moments. The theory of electromagnetic field quantization in magnetoelectric materials is used to derive general expressions for the decay rates in terms of the dyadic Green function. We focus on the decay rates in free space and near an infinite half space. For the decay of atoms near to an absorbing dielectric surface we find a hierarchy of scaling laws depending on the atom-surface distance z.
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