760 research outputs found

    Nanoscale surface relaxation of a membrane stack

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    Recent measurements of the short-wavelength (~ 1--100 nm) fluctuations in stacks of lipid membranes have revealed two distinct relaxations: a fast one (decay rate of ~ 0.1 ns^{-1}), which fits the known baroclinic mode of bulk lamellar phases, and a slower one (~ 1--10 \mu s^{-1}) of unknown origin. We show that the latter is accounted for by an overdamped capillary mode, depending on the surface tension of the stack and its anisotropic viscosity. We thereby demonstrate how the dynamic surface tension of membrane stacks could be extracted from such measurements.Comment: 4 page

    Symbiotic Solitons in Heteronuclear Multicomponent Bose-Einstein condensates

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    We show that bright solitons exist in quasi-one dimensional heteronuclear multicomponent Bose-Einstein condensates with repulsive self-interaction and attractive inter-species interaction. They are remarkably robust to perturbations of initial data and collisions and can be generated by the mechanism of modulational instability. Some possibilities for control and the behavior of the system in three dimensions are also discussed

    Novel Charge Sensitive Amplifier Design Methodology suitable for Large Detector Capacitance Applications

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    Current mode charge sensitive amplifier (CSA) topology and related methodology for use as pre-amplification block in radiation detection read out front end IC systems is proposed1. It is based on the use of a suitably configured current conveyor topology providing advantageous noise performance characteristics in comparison to the typical used CSA structures. In the proposed architecture the noise at the output of the CSA is independent of the detector capacitance value, allowing the use of large area detectors without affecting the system noise performance. Theoretical analysis and simulation analysis are performed concerning the operation – performance of the proposed topology. Measurement results on a current mode CSA prototype fabricated with a 0.35 μm CMOS process by Austriamicrosystems are provided supporting the theoretical and simulation results and confirming the performance mainly in terms of the noise performance dependency on the detector capacitance value

    On the SigmaN cusp in the pp -> pK+Lambda reaction

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    Measurements of the pppK+Λpp \to pK^+\Lambda reaction at TpT_p = 2.28 GeV have been carried out at COSY-TOF. In addition to the Λp\Lambda p FSI and NN^* resonance excitation effects a pronounced narrow structure is observed in the Dalitz plot and in its projection on the pΛp\Lambda-invariant mass. The structure appears at the pppp \to NK+ΣK^+\Sigma threshold and is interpreted as Σ\SigmaN cusp effect. The observed width of 20 MeV/c2c^2 is substantially broader than anticipated from previous inclusive measurements. Angular distributions of this cusp structure are shown to be dissimilar to those in the residual pK+ΛpK^+\Lambda channel, but similar to those observed in the pK+Σ0pK^+\Sigma^0 channel

    Time series aggregation, disaggregation and long memory

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    We study the aggregation/disaggregation problem of random parameter AR(1) processes and its relation to the long memory phenomenon. We give a characterization of a subclass of aggregated processes which can be obtained from simpler, "elementary", cases. In particular cases of the mixture densities, the structure (moving average representation) of the aggregated process is investigated

    Persistent currents of noninteracting electrons

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    We thoroughly study the persistent current of noninteracting electrons in one, two, and three dimensional thin rings. We find that the results for noninteracting electrons are more relevant for individual mesoscopic rings than hitherto appreciated. The current is averaged over all configurations of the disorder, whose amount is varied from zero up to the diffusive limit, keeping the product of the Fermi wave number and the ring's circumference constant. Results are given as functions of disorder and aspect ratios of the ring. The magnitude of the disorder-averaged current may be larger than the root-mean-square fluctuations of the current from sample to sample even when the mean free path is smaller, but not too small, than the circumference of the ring. Then a measurement of the persistent current of a typical sample will be dominated by the magnitude of the disorder averaged current.Comment: 10 pages, 4 figure

    An International Urogynecological Association (IUGA)/International Continence Society (ICS) joint report on the terminology for the conservative and nonpharmacological management of female pelvic floor dysfunction

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    There has been an increasing need for the terminology on the conservative management of female pelvic floor dysfunction to be collated in a clinically based consensus report.This Report combines the input of members and elected nominees of the Standardization and Terminology Committees of two International Organizations, the International Urogynecological Association (IUGA) and the International Continence Society (ICS), assisted at intervals by many external referees. An extensive process of nine rounds of internal and external review was developed to exhaustively examine each definition, with decision-making by collective opinion (consensus). Before opening up for comments on the webpages of ICS and IUGA, five experts from physiotherapy, neurology, urology, urogynecology, and nursing were invited to comment on the paper.A Terminology Report on the conservative management of female pelvic floor dysfunction, encompassing over 200 separate definitions, has been developed. It is clinically based, with the most common symptoms, signs, assessments, diagnoses, and treatments defined. Clarity and ease of use have been key aims to make it interpretable by practitioners and trainees in all the different specialty groups involved in female pelvic floor dysfunction. Ongoing review is not only anticipated, but will be required to keep the document updated and as widely acceptable as possible.A consensus-based terminology report for the conservative management of female pelvic floor dysfunction has been produced, aimed at being a significant aid to clinical practice and a stimulus for research

    Search for the Theta^+(1540) in lattice QCD

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    We report on a study of the pentaquark Theta^+(1540), using a variety of different interpolating fields. We use Chirally Improved fermions in combination with Jacobi smeared quark sources to improve the signal and get reliable results even for small quark masses. The results of our quenched calculations, which have been done on a 12^3 x 24 lattice with a lattice spacing of a = 0.148 fm, do not provide any evidence for the existence of a \Theta^+ with positive parity. We do observe, however, a signal compatible with nucleon-kaon scattering state. For the negative parity the results are inconclusive, due to the potential mixture with nucleon-kaon and N^*-kaon scattering states.Comment: 5 pages, 2 figure

    Physical Conditions of Accreting Gas in T Tauri Star Systems

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    We present results from a low resolution (R~300) near-infrared spectroscopic variability survey of actively accreting T Tauri stars (TTS) in the Taurus-Auriga star forming region. Paschen and Brackett series H I recombination lines were detected in 73 spectra of 15 classical T Tauri systems. The values of the Pan/PaB, Brn/BrG, and BrG/Pan H I line ratios for all observations exhibit a scatter of < 20% about the weighted mean, not only from source to source, but also for epoch-to-epoch variations in the same source. A representative or `global' value was determined for each ratio in both the Paschen and Brackett series as well as the BrG/Pan line ratios. A comparison of observed line ratio values was made to those predicted by the temperature and electron density dependent models of Case B hydrogen recombination line theory. The measured line ratios are statistically well-fit by a tightly constrained range of temperatures (T < 2000 K) and electron densities 1e9 < n_e < 1e10 cm^-3. A comparison of the observed line ratio values to the values predicted by the optically thick and thin local thermodynamic equilibrium cases rules out these conditions for the emitting H I gas. Therefore, the emission is consistent with having an origin in a non-LTE recombining gas. While the range of electron densities is consistent with the gas densities predicted by existing magnetospheric accretion models, the temperature range constrained by the Case B comparison is considerably lower than that expected for accreting gas. The cooler gas temperatures will require a non-thermal excitation process (e.g., coronal/accretion-related X-rays and UV photons) to power the observed line emission.Comment: 12 pages, emulateapj format, Accepted for publication in Ap
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