117 research outputs found
Nonlinear Magneto-Optics of freestanding Fe monolayers from first principles
The nonlinear magneto-optical Kerr-effect (NOLIMOKE) is determined for
freestanding Fe monolayers with several in-plane structures from first
principles. Based on the theory of nonlinear magneto-optics by H\"ubner and
Bennemann [Phys. Rev. B, {\bf 40}, 5973 (1989)] we calculate the nonlinear
susceptibilities of the monolayers using the ab initio FLAPW-method WIEN95 with
the additional implementation of spin-orbit coupling and the calculation of the
dipole transition matrix elements appropriate for freestanding monolayers. We
present results for the spectral dependence of the nonlinear susceptibility
tensor elements and the resulting intensities and Kerr angles. Special
emphasize is put on the effects of structural changes such as the variation of
the lattice constant and different surface orientations. The influence of
spin-orbit coupling on the tensor elements for different magnetization
directions is presented as well as the azimuthal dependence of the intensities
generated by several low index surfaces, showing the pronounced sensitivity of
second harmonic generation to lateral structural changes as well as magnetic
properties even in the monolayer range
Angular Dependences of Third Harmonic Generation from Microdroplets
We present experimental and theoretical results for the angular dependence of
third harmonic generation (THG) of water droplets in the micrometer range (size
parameter ). The THG signal in - and -polarization obtained
with ultrashort laser pulses is compared with a recently developed nonlinear
extension of classical Mie theory including multipoles of order .
Both theory and experiment yield over a wide range of size parameters
remarkably stable intensity maxima close to the forward and backward direction
at ``magic angles''. In contrast to linear Mie scattering, both are of
comparable intensity.Comment: 4 pages, RevTeX, 3 figures available on request from
[email protected], submitted to PR
Phrenic-specific transcriptional programs shape respiratory motor output
The precise pattern of motor neuron (MN) activation is essential for the execution of motor actions; however, the molecular mechanisms that give rise to specific patterns of MN activity are largely unknown. Phrenic MNs integrate multiple inputs to mediate inspiratory activity during breathing and are constrained to fire in a pattern that drives efficient diaphragm contraction. We show that Hox5 transcription factors shape phrenic MN output by connecting phrenic MNs to inhibitory pre-motor neurons. genes establish phrenic MN organization and dendritic topography through the regulation of phrenic-specific cell adhesion programs. In the absence of genes, phrenic MN firing becomes asynchronous and erratic due to loss of phrenic MN inhibition. Strikingly, mice lacking genes in MNs exhibit abnormal respiratory behavior throughout their lifetime. Our findings support a model where MN-intrinsic transcriptional programs shape the pattern of motor output by orchestrating distinct aspects of MN connectivity
Nonlinear Magneto-Optics of Fe Monolayers from first principles: Structural dependence and spin-orbit coupling strength
We calculate the nonlinear magneto-optical response of free-standing fcc
(001), (110) and (111) oriented Fe monolayers. The bandstructures are
determined from first principles using a full-potential LAPW method with the
additional implementation of spin-orbit coupling. The variation of the
spin-orbit coupling strength and the nonlinear magneto-optical spectra upon
layer orientation are investigated. We find characteristic differences which
indicate an enhanced sensitivity of nonlinear magneto-optics to surface
orientation and variation of the in-plane lattice constants. In particular the
crossover from onedimensional stripe structures to twodimensional films of
(111) layers exhibits a clean signature in the nonlinear Kerr-spectra and
demonstrates the versatility of nonlinear magneto-optics as a tool for in situ
thin-film analysis.Comment: 28 pages, RevTeX, psfig, submitted to PR
The anticonvulsive Phenhydan<sup>Âź</sup> suppresses extrinsic cell death.
Different forms of regulated cell death-like apoptosis and necroptosis contribute to the pathophysiology of clinical conditions including ischemia-reperfusion injury, myocardial infarction, sepsis, and multiple sclerosis. In particular, the kinase activity of the receptor-interacting serine/threonine protein kinase 1 (RIPK1) is crucial for cell fate in inflammation and cell death. However, despite its involvement in pathological conditions, no pharmacologic inhibitor of RIPK1-mediated cell death is currently in clinical use. Herein, we screened a collection of clinical compounds to assess their ability to modulate RIPK1-mediated cell death. Our small-scale screen identified the anti-epilepsy drug PhenhydanÂź as a potent inhibitor of death receptor-induced necroptosis and apoptosis. Accordingly, PhenhydanÂź blocked activation of necrosome formation/activation as well as death receptor-induced NF-ÎșB signaling by influencing the membrane function of cells, such as lipid raft formation, thus exerting an inhibitory effect on pathophysiologic cell death processes. By targeting death receptor signaling, the already FDA-approved PhenhydanÂź may provide new therapeutic strategies for inflammation-driven diseases caused by aberrant cell death
Instructional multimedia: An investigation of student and instructor attitudes and student study behavior
<p>Abstract</p> <p>Background</p> <p>Educators in allied health and medical education programs utilize instructional multimedia to facilitate psychomotor skill acquisition in students. This study examines the effects of instructional multimedia on student and instructor attitudes and student study behavior.</p> <p>Methods</p> <p>Subjects consisted of 45 student physical therapists from two universities. Two skill sets were taught during the course of the study. Skill set one consisted of knee examination techniques and skill set two consisted of ankle/foot examination techniques. For each skill set, subjects were randomly assigned to either a control group or an experimental group. The control group was taught with live demonstration of the examination skills, while the experimental group was taught using multimedia. A cross-over design was utilized so that subjects in the control group for skill set one served as the experimental group for skill set two, and vice versa. During the last week of the study, students and instructors completed written questionnaires to assess attitude toward teaching methods, and students answered questions regarding study behavior.</p> <p>Results</p> <p>There were no differences between the two instructional groups in attitudes, but students in the experimental group for skill set two reported greater study time alone compared to other groups.</p> <p>Conclusions</p> <p>Multimedia provides an efficient method to teach psychomotor skills to students entering the health professions. Both students and instructors identified advantages and disadvantages for both instructional techniques. Reponses relative to instructional multimedia emphasized efficiency, processing level, autonomy, and detail of instruction compared to live presentation. Students and instructors identified conflicting views of instructional detail and control of the content.</p
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