1,053 research outputs found
Collective Feshbach scattering of a superfluid droplet from a mesoscopic two-component Bose-Einstein condensate
We examine the collective scattering of a superfluid droplet impinging on a
mesoscopic Bose-Einstein condensate (BEC) as a target. The BEC consists of an
atomic gas with two internal electronic states, each of which is trapped by a
finite-depth external potential. An off-resonant optical laser field provides a
localized coupling between the BEC components in the trapping region. This
mesoscopic scenario matches the microscopic setup for Feshbach scattering of
two particles, when a bound state of one sub-manifold is embedded in the
scattering continuum of the other sub-manifold. Within the mean-field picture,
we obtain resonant scattering phase shifts from a linear response theory in
agreement with an exact numerical solution of the real time scattering process
and simple analytical approximations thereof. We find an energy-dependent
transmission coefficient that is controllable via the optical field between 0
and 100%.Comment: 4 Latex pages, including 4 figure
Histopathological Analysis of PEEK Wear Particle Effects on the Synovial Tissue of Patients
Introduction. Increasing interest developed in the use of carbon-fiber-reinforced-poly-ether-ether-ketones (CFR-PEEK) as an alternative bearing material in knee arthroplasty. The effects of CFR-PEEK wear in in vitro and animal studies are controversially discussed, as there are no data available concerning human tissue. The aim of this study was to analyze human tissue containing CFR-PEEK as well as UHMWPE wear debris. The authors hypothesized no difference between the used biomaterials. Methods and Materials. In 10 patients during knee revision surgery of a rotating-hinge-knee-implant-design, synovial tissue samples were achieved (tibial inserts: UHMWPE;bushings and flanges: CFR-PEEK). One additional patient received revision surgery without any PEEK components as a control. The tissue was paraffin-embedded, sliced into 2 mu m thick sections, and stained with hematoxylin and eosin in a standard process. A modified panoptical staining was also done. Results. A "wear-type" reaction was seen in the testing and the control group. In all samples, the UHMWPE particles were scattered in the tissue or incorporated in giant cells. CFR-PEEK particles were seen as conglomerates and only could be found next to vessels. CFR-PEEK particles showed no giant-cell reactions. In conclusion, the hypothesis has to be rejected. UHMWPE and PEEK showed a different scatter-behavior in human synovial tissue
Optical properties of tungsten thin films perforated with a bidimensional array of subwavelength holes
We present a theorical investigation of the optical transmission of a
dielectric grating carved in a tungsten layer. For appropriate wavelengths
tungsten shows indeed a dielectric behaviour. Our numerical simulations leads
to theoretical results similar to those found with metallic systems studied in
earlier works. The interpretation of our results rests on the idea that the
transmission is correlated with the resonant response of eigenmodes coupled to
evanescent diffraction orders.Comment: 4 pages, 3 figure
Theory of extraordinary optical transmission through subwavelength hole arrays
We present a fully three-dimensional theoretical study of the extraordinary
transmission of light through subwavelength hole arrays in optically thick
metal films. Good agreement is obtained with experimental data. An analytical
minimal model is also developed, which conclusively shows that the enhancement
of transmission is due to tunneling through surface plasmons formed on each
metal-dielectric interfaces. Different regimes of tunneling (resonant through a
''surface plasmon molecule", or sequential through two isolated surface
plasmons) are found depending on the geometrical parameters defining the
system.Comment: 4 pages, 4 figure
Electronic properties and Fermi surface of Ag(111) films deposited onto H-passivated Si(111)-(1x1) surfaces
Silver films were deposited at room temperature onto H-passivated Si(111)
surfaces. Their electronic properties have been analyzed by angle-resolved
photoelectron spectroscopy. Submonolayer films were semiconducting and the
onset of metallization was found at a Ag coverage of 0.6 monolayers. Two
surface states were observed at -point in the metallic films,
with binding energies of 0.1 and 0.35 eV. By measurements of photoelectron
angular distribution at the Fermi level in these films, a cross-sectional cut
of the Fermi surface was obtained. The Fermi vector determined along different
symmetry directions and the photoelectron lifetime of states at the Fermi level
are quite close to those expected for Ag single crystal. In spite of this
concordance, the Fermi surface reflects a sixfold symmetry rather than the
threefold symmetry of Ag single crystal. This behavior was attributed to the
fact that these Ag films are composed by two domains rotated 60.Comment: 9 pages, 8 figures, submitted to Physical Review
Positron lifetime measurements on neutronâirradiated InP crystals
Neutronâirradiated InP single crystals have been investigated by positronâlifetime measurements. The samples were irradiated with thermal neutrons at different fluences yielding concentrations for Snâtransmuted atoms between 2Ă1015 and 2Ă1018 cmâ3. The lifetime spectra have been analyzed into one exponential decay component. The mean lifetimes show a monotonous increase with the irradiation dose from 246 to 282 ps. The increase in the lifetime has been associated to a defect containing an Indium vacancy. Thermal annealing at 550â°C reduces the lifetime until values closed to those obtained for the asâgrown and conventionally doped InP [email protected] ; [email protected]
Characterisation of feline renal cortical fibroblast cultures and their transcriptional response to transforming growth factor beta 1
Chronic kidney disease (CKD) is common in geriatric cats, and the most prevalent pathology is chronic tubulointerstitial inflammation and fibrosis. The cell type predominantly responsible for the production of extra-cellular matrix in renal fibrosis is the myofibroblast, and fibroblast to myofibroblast differentiation is probably a crucial event. The cytokine TGF-ÎČ1 is reportedly the most important regulator of myofibroblastic differentiation in other species. The aim of this study was to isolate and characterise renal fibroblasts from cadaverous kidney tissue of cats with and without CKD, and to investigate the transcriptional response to TGF-ÎČ1
Anomalous Hopping Exponents of Ultrathin Films of Metals
The temperature dependence of the resistance R(T) of ultrathin
quench-condensed films of Ag, Bi, Pb and Pd has been investigated. In the most
resistive films, R(T)=Roexp(To/T)^x, where x=0.75. Surprisingly, the exponent x
was found to be constant for a wide range of Ro and To in all four materials,
possibly implying a consistent underlying conduction mechanism. The results are
discussed in terms of several different models of hopping conduction.Comment: 6 pages, 5 figure
TNF-Receptor Inhibitor Therapy for the Treatment of Children with Idiopathic Pneumonia Syndrome. A Joint Pediatric Blood and Marrow Transplant Consortium and Children's Oncology Group Study (ASCT0521)
AbstractIdiopathic pneumonia syndrome (IPS) is an acute, noninfectious lung disorder associated with high morbidity and mortality after hematopoietic cell transplantation. Previous studies have suggested a role for TNFα in the pathogenesis of IPS. We report a multicenter phase II trial investigating a soluble TNF-binding protein, etanercept (Enbrel, Amgen, Thousand Oaks, CA), for the treatment of pediatric patients with IPS. Eligible patients were < 18 years old, within 120 days after transplantation, and with radiographic evidence of a diffuse pneumonitis. All patients underwent a pretherapy broncho-alveolor lavage (BAL) to establish the diagnosis of IPS. Systemic corticosteroids (2.0 mg/kg/day) plus etanercept (.4 mg/kg twice weekly à 8 doses) were administered. Response was defined as survival and discontinuation of supplemental oxygen support by day 28 of study. Thirty-nine patients (median age, 11 years; range, 1 to 17) were enrolled, with 11 of 39 patients nonevaluable because of identification of pathogens from their pretherapy BAL. In the remaining 28 patients, the median fraction of inspired oxygen at study entry was 45%, with 17 of 28 requiring mechanical ventilation. Complete responses were seen in 20 (71%) patients, with a median time to response of 10 days (range, 1 to 24). Response rates were higher for patients not requiring mechanical ventilation at study entry (100% versus 53%, P = .01). Overall survival at 28 days and 1 year after therapy were 89% (95% confidence interval [CI], 70% to 96%) and 63% (95% CI, 42% to 79%), respectively. Plasma levels of proinflammatory cytokines were significantly increased at onset of therapy, subsequently decreasing in responding patients. The addition of etanercept to high-dose corticosteroids was associated with high response rates and survival in children with IPS
The Hamburg/ESO R-process Enhanced Star survey (HERES) VI. The Galactic Chemical Evolution of Silicon
We determined the silicon abundances of 253 metal-poor stars in the
metallicity range , based on non-local thermodynamic
equilibrium (NLTE) line formation calculations of neutral silicon and
high-resolution spectra obtained with VLT-UT2/UVES. The
dependence of [Si/Fe] noticed in previous investigation is diminished in our
abundance analysis due to the inclusion of NLTE effects. An increasing slope of
[Si/Fe] towards decreasing metallicity is present in our results, in agreement
with Galactic chemical evolution models. The small intrinsic scatter of [Si/Fe]
in our sample may imply that these stars formed in a region where the yields of
type II supernovae were mixed into a large volume, or that the formation of
these stars was strongly clustered, even if the ISM was enriched by single SNa
II in a small mixing volume. We identified two dwarfs with
: HE 01313953, and HE 14301123. These
main-sequence turnoff stars are also carbon-enhanced. They might have been
pre-enriched by sub-luminous supernovae.Comment: 12 pages, 9 figures, 1 electronical table. Accepted by A &
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