22,955 research outputs found
Lagrangian description of world-line deviations
We introduce a Lagrangian which can be varied to give both the equation of
motion and world-line deviations of spinning particles simultaneously.Comment: to appear in IJT
Direct and alignment-insensitive measurement of cantilever curvature
We analytically derive and experimentally demonstrate a method for the
simultaneous measurement of deflection for large arrays of cantilevers. The
Fresnel diffraction patterns of a cantilever independently reveals tilt,
curvature, cubic and higher order bending of the cantilever. It provides a
calibrated absolute measurement of the polynomial coefficients describing the
cantilever shape, without careful alignment and could be applied to several
cantilevers simultaneously with no added complexity. We show that the method is
easily implemented, works in both liquid mediums and in air, for a broad range
of displacements and is especially suited to the requirements for multi-marker
biosensors.Comment: 5 Pages, 4 figures, letter forma
General relativistic spinning fluids with a modified projection tensor
An energy-momentum tensor for general relativistic spinning fluids compatible
with Tulczyjew-type supplementary condition is derived from the variation of a
general Lagrangian with unspecified explicit form. This tensor is the sum of a
term containing the Belinfante-Rosenfeld tensor and a modified perfect-fluid
energy-momentum tensor in which the four-velocity is replaced by a unit
four-vector in the direction of fluid momentum. The equations of motion are
obtained and it is shown that they admit a Friedmann-Robertson-Walker
space-time as a solution.Comment: Submitted to General Relativity and Gravitatio
Free clinics in the United States : an exploratory review
Free clinics are spread across the nation and serve millions of the poor and uninsured in our communities. As these clinics strive to provide quality care for their patients who have fallen through the cracks of the health care system they face many issues. The purpose of this paper was to use previous research and literature to develop a better understanding of free clinics as a collective whole with hopes of learning more about the issues they face in the process. By showing how clinics are organized and funded, what types of patients they see for what reason, and how they are staffed with medical professionals, it can be seen how they work and what purpose they serve.Honors CollegeThesis (B.?.
Open and Closed Loop Stability of Hingeless Rotor Helicopter Air and Ground Resonance
The air and ground resonance instabilities of hingeless rotor helicopters are examined on a relatively broad parametric basis including the effects of blade tuning, virtual hinge locations, and blade hysteresis damping, as well as size and scale effects in the gross weight range from 5,000 to 48,000 pounds. A special case of a 72,000 pound helicopter air resonance instability is also included. The study shows that nominal to moderate and readily achieved levels of blade inertial hysteresis damping in conjunction with a variety of tuning and/or feedback conditions are highly effective in dealing with these instabilities. Tip weights and reductions in pre-coning angles are also shown to be effective means for improving the air resonance instability
Atherosusceptible Shear Stress Activates Endoplasmic Reticulum Stress to Promote Endothelial Inflammation.
Atherosclerosis impacts arteries where disturbed blood flow renders the endothelium susceptible to inflammation. Cytokine activation of endothelial cells (EC) upregulates VCAM-1 receptors that target monocyte recruitment to atherosusceptible regions. Endoplasmic reticulum (ER) stress elicits EC dysregulation in metabolic syndrome. We hypothesized that ER plays a central role in mechanosensing of atherosusceptible shear stress (SS) by signaling enhanced inflammation. Aortic EC were stimulated with low-dose TNFα (0.3 ng/ml) in a microfluidic channel that produced a linear SS gradient over a 20mm field ranging from 0-16 dynes/cm2. High-resolution imaging of immunofluorescence along the monolayer provided a continuous spatial metric of EC orientation, markers of ER stress, VCAM-1 and ICAM-1 expression, and monocyte recruitment. VCAM-1 peaked at 2 dynes/cm2 and decreased to below static TNFα-stimulated levels at atheroprotective-SS of 12 dynes/cm2, whereas ICAM-1 rose to a maximum in parallel with SS. ER expansion and activation of the unfolded protein response also peaked at 2 dynes/cm2, where IRF-1-regulated VCAM-1 expression and monocyte recruitment also rose to a maximum. Silencing of PECAM-1 or key ER stress genes abrogated SS regulation of VCAM-1 transcription and monocyte recruitment. We report a novel role for ER stress in mechanoregulation at arterial regions of atherosusceptible-SS inflamed by low-dose TNFα
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