175 research outputs found
Team OmniMouse
INFORMATION, DATA, FIGURES AND DRAWINGS EMBODIED IN THIS DOCUMENT ARE STRICTLY CONFIDENTIAL AND ARE SUPPLIED ON THE UNDERSTANDING THAT THEY WILL NOT BE DISCLOSED TO THIRD PARTIES WITHOUT THE PRIOR WRITTEN CONSENT OF QUALITY OF LIFE PLUS
Biomechanical Tolerance of Whole Lumbar Spines in Straightened Posture Subjected to Axial Acceleration
Quantification of biomechanical tolerance is necessary for injury prediction and protection of vehicular occupants. This study experimentally quantified lumbar spine axial tolerance during accelerative environments simulating a variety of military and civilian scenarios. Intact human lumbar spines (T12âL5) were dynamically loaded using a customâbuilt drop tower. Twentyâthree specimens were tested at subâfailure and failure levels consisting of peak axial forces between 2.6 and 7.9âkN and corresponding peak accelerations between 7 and 57âg. Military aircraft ejection and helicopter crashes fall within these high axial acceleration ranges. Testing was stopped following injury detection. Both peak force and acceleration were significant (pâ\u3câ0.0001) injury predictors. Injury probability curves using parametric survival analysis were created for peak acceleration and peak force. Fiftyâpercent probability of injury (95%CI) for force and acceleration were 4.5 (3.9â5.2âkN), and 16 (13â19âg). A majority of injuries affected the L1 spinal level. Peak axial forces and accelerations were greater for specimens that sustained multiple injuries or injuries at L2âL5 spinal levels. In general, forceâbased tolerance was consistent with previous shorterâsegment lumbar spine testing (3â5 vertebrae), although studies incorporating isolated vertebral bodies reported higher tolerance attributable to a different injury mechanism involving structural failure of the cortical shell. This study identified novel outcomes with regard to injury patterns, wherein more violent exposures produced more injuries in the caudal lumbar spine. This caudal migration was likely attributable to increased injury tolerance at lower lumbar spinal levels and a faster inertial mass recruitment process for high rate load application. Published 2017. This article is a U.S. Government work and is in the public domain in the USA
Entangling Two Bose-Einstein Condensates by Stimulated Bragg Scattering
We propose an experiment for entangling two spatially separated Bose-Einstein
condensates by Bragg scattering of light. When Bragg scattering in two
condensates is stimulated by a common probe, the resulting quasiparticles in
the two condensates get entangled due to quantum communication between the
condensates via probe beam. The entanglement is shown to be significant and
occurs in both number and quadrature phase variables. We present two methods of
detecting the generated entanglement.Comment: 4 pages, Revte
Impact of Baseline Retinal Nonperfusion and Macular Retinal Capillary Nonperfusion on Outcomes in the COPERNICUS and GALILEO Studies
To evaluate the impact of baseline retinal capillary nonperfusion (RNP) and macular retinal capillary nonperfusion (MNP) status on outcomes at week 24 (W24)
Spin squeezing and entanglement in spinor-1 condensates
We analyze quantum correlation properties of a spinor-1 (f=1) Bose Einstein
condensate using the Gell-Mann realization of SU(3) symmetry. We show that
previously discussed phenomena of condensate fragmentation and spin-mixing can
be explained in terms of the hypercharge symmetry. The ground state of a
spinor-1 condensate is found to be fragmented for ferromagnetic interactions.
The notion of two bosonic mode squeezing is generalized to the two spin (U-V)
squeezing within the SU(3) formalism. Spin squeezing in the isospin subspace
(T) is found and numerically investigated. We also provide new results for the
stationary states of spinor-1 condensates.Comment: 9 pages, 6 figure
Maghemite nanoparticles bearing di(amidoxime) groups for the extraction of uranium from wastewaters
Polyamidoximes (pAMD) are known to have strong affinities for uranyl cations. Grafting pAMD onto the surface of functionalized maghemite nanoparticles (MNP) leads to a nanomaterial with high capacities in the extraction of uranium from wastewaters by magnetic sedimentation. A diamidoxime (dAMD) specifically synthesized for this purpose showed a strong affinity for uranyl: Ka = 105 M-1 as determined by Isothermal Titration Calorimetry (nano-ITC). The dAMD was grafted onto the surface of MNP and the obtained sorbent (MNP-dAMD) was characterized. The nanohybrids were afterward incubated with different concentrations of uranyl and the solid phase recovered by magnetic separation. This latter was characterized by zeta-potential measurements, X-Ray Photoelectron Spectroscopy (XPS) and X-Ray Fluorescence spectroscopy (XRF), whereas the supernatant was analyzed by Inductively Coupled Plasma coupled to Mass Spectrometry (ICP-MS). All the data fitted the models of Langmuir, Freundlich and Temkin isotherms very well. These isotherms allowed us to evaluate the efficiency of the adsorption of uranium by MNP-dAMD. The saturation sorption capacity (qmax) was determined. It indicates that MNP-dAMD is able to extract up to 120 mg of uranium per gram of sorbent. Spherical aberration (Cs)-corrected High-Resolution Scanning Transmission Electron Microscopy (HRSTEM) confirmed these results and clearly showed that uranium is confined at the surface of the sorbent. Thus, MNP-dAMD presents a strong potential for the extraction of uranium from wastewaters
The dynamics of quantum phases in a spinor condensate
We discuss the quantum phases and their diffusion dynamics in a spinor-1
atomic Bose-Einstein condensate. For ferromagnetic interactions, we obtain the
exact ground state distribution of the phases associated with the total atom
number (), the total magnetization (), and the alignment (or
hypercharge) () of the system. The mean field ground state is stable against
fluctuations of atom numbers in each of the spin components, and the phases
associated with the order parameter for each spin components diffuse while
dynamically recover the two broken continuous symmetries [U(1) and SO(2)] when
and are conserved as in current experiments. We discuss the
implications to the quantum dynamics due to an external (homogeneous) magnetic
field. We also comment on the case of a spinor-1 condensate with
anti-ferromagnetic interactions.Comment: 5 figures, an extended version of cond-mat/030117
Minimizing the source of nociception and its concurrent effect on sensory hypersensitivity: An exploratory study in chronic whiplash patients
Abstract. Background. The cervical zygapophyseal joints may be a primary source of pain in up to 60% of individuals with chronic whiplash associated disorders (WAD) and may be a contributing factor for peripheral and centrally mediated pain (sensory hypersensitivity). Sensory hypersensitivity has been associated with a poor prognosis. The purpose of the study was to determine if there is a change in measures indicative of sensory hypersensitivity in patients with chronic WAD grade II following a medial branch block (MBB) procedure in the cervical spine. Methods. Measures of sensory hypersensitivity were taken via quantitative sensory testing (QST) consisting of pressure pain thresholds (PPT's) and cold pain thresholds (CPT's). In patients with chronic WAD (n = 18), the measures were taken at three sites bilaterally, pre- and post- MBB. Reduced pain thresholds at remote sites have been considered an indicator of central hypersensitivity. A healthy age and gender matched comparison group (n = 18) was measured at baseline. An independent t-test was applied to determine if there were any significant differences between the WAD and normative comparison groups at baseline with respect to cold pain and pressure pain thresholds. A dependent t-test was used to determine whether there were any significant differences between the pre and post intervention cold pain and pressure pain thresholds in the patients with chronic WAD. Results. At baseline, PPT's were decreased at all three sites in the WAD group (p < 0.001). Cold pain thresholds were increased in the cervical spine in the WAD group (p < 0.001). Post-MBB, the WAD group showed significant increases in PPT's at all sites (p < 0.05), and significant decreases in CPT's at the cervical spine (p < 0.001). Conclusions. The patients with chronic WAD showed evidence of widespread sensory hypersensitivity to mechanical and thermal stimuli. The WAD group revealed decreased sensory hypersensitivity following a decrease in their primary source of pain stemming from the cervical zygapophyseal joints
Creating a model of diseased artery damage and failure from healthy porcine aorta
Large quantities of diseased tissue are required in the research and development of new generations of medical devices, for example for use in physical testing. However, these are difficult to obtain. In contrast, porcine arteries are readily available as they are regarded as waste. Therefore, reliable means of creating from porcine tissue physical models of diseased human tissue that emulate well the associated mechanical changes would be valuable. To this end, we studied the effect on mechanical response of treating porcine thoracic aorta with collagenase, elastase and glutaraldehyde. The alterations in mechanical and failure properties were assessed via uniaxial tension testing. A constitutive model composed of the Gasser-Ogden-Holzapfel model, for elastic response, and a continuum damage model, for the failure, was also employed to provide a further basis for comparison (Calvo and Pena, 2006 and Gasser et al., 2006). For the concentrations used here it was found that: collagenase treated samples showed decreased fracture stress in the axial direction only; elastase treated samples showed increased fracture stress in the circumferential direction only; and glutaraldehyde samples showed no change in either direction. With respect to the proposed constitutive model, both collagenase and elastase had a strong effect on the fibre-related terms. The model more closely captured the tissue response in the circumferential direction, due to the smoother and sharper transition from damage initiation to complete failure in this direction. Finally, comparison of the results with those of tensile tests on diseased tissues suggests that these treatments indeed provide a basis for creation of physical models of diseased arteries
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