516 research outputs found
T-duality and Generalized Complex Geometry
We find the explicit T-duality transformation in the phase space formulation
of the N=(1,1) sigma model. We also show that the T-duality transformation is a
symplectomorphism and it is an element of O(d,d). Further, we find the explicit
T-duality transformation of a generalized complex structure in this model. We
also show that the extended supersymmetry of the sigma model is preserved under
the T-duality.Comment: 18 pages; added references; published versio
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LIQUID XENON MULTIWIRE PROPORTIONAL CHAMBERS FOR NUCLEAR MEDICINEAPPLICATIONS
The need for improved spatial resolution in nuclear medicine has long been recognized. Notable attempts to achieve this goal are the gas-filled wire chambers and solid-state detectors. (1) However, at energies above 100 keV, gas-filled chambers suffer from poor detection efficiency and a long recoil electron range in the gas. While it is advantageous to pressurize these chambers to 10 or more atmospheres, structural design of the thin window presents a formidable task. High-resolution optimal collimators do not appear to have sufficient strength to be used as a pressure support window. Solid-state detectors, while having the potential of a gamma camera with a superb energy resolution, are presently studied on a very small scale due to technological and cost limitations. Aside from the detector, the parallel-hole collimator presents a real limit to the resolution of the camera. A factor of two improvement in the resolution results in a factor of four loss in the collimator's transmission. A careful analysis of optimal collimators and the application of collimators designed for a specific depth range and resoluation are part of our overall program. Our goal has been the development of a liquid-xenon multiwire gamma camera with 2- to 3-mm spatial resolution, high counting-rate performance, high sensitivity, and the potential for scaling-up in size. Important ingredients for successful imaging in the prototype chamber discussed in this paper were the discovery of electron multiplication in liquid xenon, (2) the development of reliable purification techniques, (3) and the ability to extract electrons from the liquid into the gaseous phase. This paper is specifically addressed to the subject of detector development with liquid-xenon totally-filled chambers and recent work with dual-phase chambers in which the {gamma} rays are converted in the liquid phase and are electronically detected in the gaseous phase
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LIQUID XENON FILLED WIRE CHAMBERS FOR MEDICAL IMAGINGAPPLICATIONS
In 1968, Luis Alvarez suggested that a high-resolution multiwire particle detector could be developed using a thin layer of liquified noble gas as the detection medium. After key problems in chamber construction, purification, and readout had been solved, a spatial resolution of 15 {micro} rms was demonstrated. Work is in progress to build high-resolution chambers and measure their properties for particle physics experiments at high-energy accelerators. The liquid xenon multiwire chamber also has potential in nuclear medicine for imaging isotope distributions with an unprecedented combination of gamma-ray detection efficiency and spatial resolution. A preliminary 24-wire chamber has been constructed; this chamber detects 280-keV gamma rays with 65% efficiency and 4-mm FWHM spatial resolution. Initial images of point and distributed sources are very promising, and the liquid purity can be maintained for periods exceeding several days
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HIGH-RESOLUTION LIQUID-FILLED MULTI-WIRE CHAMBERS FOR USE INHIGH-ENERGY BEAMS
The authors describe experiments with liquid-xenon-filled wire chambers operating in the proportional mode and the difficulty of achieving useful gain when the anode wires have a spacing < 1 mm. As a result, they have largely turned our attention to chambers with closely spaced wires operated in the ionization mode. They have previously demonstrated a spatial resolution of 15 {micro} rms in this mode, using a 5-wire chamber and a collimated alpha source. They describe the construction of two small high-resolution test chambers to be filled with liquid argon, krypton, or xenon. The chambers consist of two flat cathodes 1 to 2.5 mm apart with a wire plane between them. The wire plane is an array of 24 wires, 5 {micro} in diameter, spaced on 20-{micro} centers, and a charge amplifier is attached to each wire. The space resolution (expected rms < 20 {micro}), time resolution (expected rms < 50 ns), and efficiency will be measured in an accelerator beam. Chambers of this type with only a few hundred wires have sufficient area to cover nearly every beam at NAL
Detection potential to point-like neutrino sources with the NEMO-km3 telescope
The NEMO Collaboration is conducting an R&D activity towards the construction
of a Mediterranean km3 neutrino telescope. In this work, we present the results
of Monte Carlo simulation studies on the capability of the proposed NEMO
telescope to detect and identify point-like sources of high energy muon
neutrinos.Comment: To be published on BCN06 proceedings (Barcelona, July 4-7, 2006
Efficacy, safety and patient reported outcomes (PROS) in adult patients with atopic dermatitis treated with dupilumab at week-52 in usual clinical practice
P15
Background: Dupilumab, an anti-interleikin-4-receptor-a monoclonal antibody, is a new treatment for atopic dermatitis in adults.
Objective: To evaluate – at week 52 – patient reported outcomes, satisfaction, efficacy and safety, with dupilumab in adult patients with moderate-to-severe atopic dermatitis refractory to the usual treatments previously performed under conditions of usual clinical practice.
Methods: Twelve patients were enrolled. Patients from our hospital, under routine clinical practice, were treated with subcutaneous dupilumab 300 mg every 2 weeks. The outcomes were evaluated at baseline, week 4, 8, 12, 16, 28 , 40 and week 52. The variables evaluated were: itch, difficulty to sleep, previous stressful life events, severity (SCORAD), anxiety and depression symptoms (HADS), quality of life (DLQI, EQ5D3L), satisfaction, adherence to the treatment, efficacy and safety.
Results: At week 52 significant improvement was observed in severity, itch, difficulty to sleep, anxiety and depression symptoms, and quality of life. Satisfaction with dupilumab compared to previous treatments was significantly higher in all aspects assessed. No significant dupilumab-induced laboratory abnormalities were noted, and adverse events were mild and transient.
Conclusions: Dupilumab used under routine clinical practice for 52 weeks improved atopic dermatitis signs and symptoms, with a good safety profile and patient satisfaction
A model for net-baryon rapidity distribution
In nuclear collisions, a sizable fraction of the available energy is carried
away by baryons. As the baryon number is conserved, the net-baryon
retains information on the energy-momentum carried by the incoming nuclei. A
simple and consistent model for net-baryon production in high energy
proton-proton and nucleus-nucleus collisions is presented. The basic
ingredients of the model are valence string formation based on standard PDFs
with QCD evolution and string fragmentation via the Schwinger mechanism. The
results of the model are presented and compared with data at different
centre-of-mass energies and centralities, as well as with existing models.
These results show that a good description of the main features of net-baryon
data is possible in the framework of a simplistic model, with the advantage of
making the fundamental production mechanisms manifest.Comment: 9 pages, 12 figures; in fig. 11 a) the vertical scale was correcte
Giant Shapiro steps for two-dimensional Josephson-junction arrays with time-dependent Ginzburg-Landau dynamics
Two-dimensional Josephson junction arrays at zero temperature are
investigated numerically within the resistively shunted junction (RSJ) model
and the time-dependent Ginzburg-Landau (TDGL) model with global conservation of
current implemented through the fluctuating twist boundary condition (FTBC).
Fractional giant Shapiro steps are found for {\em both} the RSJ and TDGL cases.
This implies that the local current conservation, on which the RSJ model is
based, can be relaxed to the TDGL dynamics with only global current
conservation, without changing the sequence of Shapiro steps. However, when the
maximum widths of the steps are compared for the two models some qualitative
differences are found at higher frequencies. The critical current is also
calculated and comparisons with earlier results are made. It is found that the
FTBC is a more adequate boundary condition than the conventional uniform
current injection method because it minimizes the influence of the boundary.Comment: 6 pages including 4 figures in two columns, final versio
Using screen video capture software to aide and inform cognitive interviewing
Web-based surveys are a salient tool in the repertoire of social and behavioral scientists. The increase in web-based surveys is understandable considering the distinct advantages offered, including: (a) lower costs and reduced labor time, (b) ability to directly transfer data into statistical packages (reducing coding errors), (c) customization options enabling more attractive presentation, (d) ability to reduce respondent burden by embedding skip patterns, and (e) access to larger sample sizes in different geographic regions. It is important to note, however, that administering web-based surveys also introduces distinct sources of error (e.g., coverage, sampling and non-response). Regardless of format (e.g., paper-and-pencil or web-based), specific, prescribed steps must be followed when constructing an instrument in order to reduce survey error and lend credence to the data collected before subsequent analysis is performed. One of those crucial stages integral to the pretesting process is cognitive interviewing. Cognitive interviewing is a qualitative process, encompassing two main techniques: think aloud interviewing and verbal probing. Collectively, these two methods seek to (a) produce information on what the respondent is thinking while answering the questions, (b) the cognitive processes used to answer the questions, and (c) how the respondent answers the questions. The purpose of this article is to provide a practical guide outlining how Camtasia, a screen video capture software, can aide and inform the cognitive interview process
Patient reported outcomes (PROS) in psoriasis patients
P20
Introduction: Psoriasis is a chronic skin disease with negative physical, mental and social manifestations. Method: We carried out a longitudinal and prospective study under routine clinical practice conditions. The objective of the study was to measure quality of life with the Short Form-36 Survey (SF-36) and correlate the results with clinical variables using the PASI and BSA in a group of 17 patients with moderate to severe psoriasis treated with Ustekinumab. Results: In the baseline evaluation we observed the following results: 35.3% reported physical malfunction, 64.7% debilitating pain, 82.3% poor health in general, 76.4% bad vitality, 88.2% social malfunction, 100% emotional malfunction and 82.3% poor mental health. At week 78 we observed the following results: 41.15% reported very good physical functioning, 76.1% no pain, 58.8% good general health, 58.8% very good vitality, 70%, 5% good social functioning, 70.5% good emotional functioning and 52.9% good mental health. Conclusion: We observed that the perception of patients with moderate-severe psoriasis regarding their health at the beginning of treatment with Ustekinumab was poor and that they experienced a significant improvement throughout the successive weeks of treatment
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