5,203 research outputs found
Transition from Poisson to gaussian unitary statistics: The two-point correlation function
We consider the Rosenzweig-Porter model of random matrix which interpolates
between Poisson and gaussian unitary statistics and compute exactly the
two-point correlation function. Asymptotic formulas for this function are given
near the Poisson and gaussian limit.Comment: 19 pages, no figure
Navy composite maintenance and repair experience
The Navy has been a strong proponent of composites for aircraft structure. Fleet use of composites started with the F-14 in the early 1970's and has steadily increased. This experience base provides sufficient information to allow an evaluation of the maintenance performance of polymer composites in service. A summary is presented of the Navy's experience with maintenance of composite structure. The general types of damage experienced in the fleet as well as specific examples of composite damage to aircraft is described. The impact of future designs on supportability is also discussed
Radiative Losses in Plasma Accelerators
We investigate the dynamics of a relativistic electron in a strongly
nonlinear plasma wave in terms of classical mechanics by taking into account
the action of the radiative reaction force. The two limiting cases are
considered. In the first case where the energy of the accelerated electrons is
low, the electron makes many betatron oscillations during the acceleration. In
the second case where the energy of the accelerated electrons is high, the
betatron oscillation period is longer than the electron residence time in the
accelerating phase. We show that the force of radiative friction can severely
limit the rate of electron acceleration in a plasma accelerator.Comment: 17 pages, 5 figure
Assessing Ozone-Related Health Impacts under a Changing Climate
Climate change may increase the frequency and intensity of ozone episodes in future summers in the United States. However, only recently have models become available that can assess the impact of climate change on O(3) concentrations and health effects at regional and local scales that are relevant to adaptive planning. We developed and applied an integrated modeling framework to assess potential O(3)-related health impacts in future decades under a changing climate. The National Aeronautics and Space AdministrationâGoddard Institute for Space Studies global climate model at 4° Ă 5° resolution was linked to the Penn State/National Center for Atmospheric Research Mesoscale Model 5 and the Community Multiscale Air Quality atmospheric chemistry model at 36 km horizontal grid resolution to simulate hourly regional meteorology and O(3) in five summers of the 2050s decade across the 31-county New York metropolitan region. We assessed changes in O(3)-related impacts on summer mortality resulting from climate change alone and with climate change superimposed on changes in O(3) precursor emissions and population growth. Considering climate change alone, there was a median 4.5% increase in O(3)-related acute mortality across the 31 counties. Incorporating O(3) precursor emission increases along with climate change yielded similar results. When population growth was factored into the projections, absolute impacts increased substantially. Counties with the highest percent increases in projected O(3) mortality spread beyond the urban core into less densely populated suburban counties. This modeling framework provides a potentially useful new tool for assessing the health risks of climate change
Non-universality of compact support probability distributions in random matrix theory
The two-point resolvent is calculated in the large-n limit for the generalized fixed and bounded trace ensembles. It is shown to disagree with that of the canonical Gaussian ensemble by a nonuniversal part that is given explicitly for all monomial potentials V(M)=M2p. Moreover, we prove that for the generalized fixed and bounded trace ensemble all k-point resolvents agree in the large-n limit, despite their nonuniversality
A superconducting levitation transport model system for dynamical and didactical studies
Superconducting levitation transport systems might become very attractive in the near future due to various reasons. The realisation of contactless systems allows e.g. extended maintenance-free operation with high efficiency since such a system only needs energy for cooling and propulsion. We established a small superconducting levitation transport model system called "SupraTrans Mini" consisting of permanent magnetic rails and a levitated vehicle including four YBCO-bulk samples in a cryostat. The rail system consists of an oval shaped loop (2.90 m x 1.44 m), which was build up from individual linear and curved track modules. Inside the vehicle position variations of the superconductors are possible. By means of velocity, acceleration and temperature measurements different dynamical aspects of our complex levitation system can be investigated. We also show the broad applicability of the experimental setup for didactical studies in physics
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A superconducting levitation transport model system for dynamical and didactical studies
Superconducting levitation transport systems might become very attractive in the near future due to various reasons. The realisation of contactless systems allows e.g. extended maintenance-free operation with high efficiency since such a system only needs energy for cooling and propulsion. We established a small superconducting levitation transport model system called "SupraTrans Mini" consisting of permanent magnetic rails and a levitated vehicle including four YBCO-bulk samples in a cryostat. The rail system consists of an oval shaped loop (2.90 m x 1.44 m), which was build up from individual linear and curved track modules. Inside the vehicle position variations of the superconductors are possible. By means of velocity, acceleration and temperature measurements different dynamical aspects of our complex levitation system can be investigated. We also show the broad applicability of the experimental setup for didactical studies in physics
Semiclassical wave equation and exactness of the WKB method
The exactness of the semiclassical method for three-dimensional problems in
quantum mechanics is analyzed. The wave equation appropriate in the
quasiclassical region is derived. It is shown that application of the standard
leading-order WKB quantization condition to this equation reproduces exact
energy eigenvalues for all solvable spherically symmetric potentials.Comment: 13 page
The common NOD2/CARD15 variant P268S in patients with non-infectious uveitis: a cohort study
Background: The etiology of Autoimmune chronic uveitis (ACU) is still unknown; NOD2/CARD15 gene mutations are responsible for the Blau Syndrome and can induce uveitis in animal models. Presentation of the hypothesis: Aim of our study was to assess if NOD2/CARD15 variants have a role in the etiology or in the clinical course of patients with ACU, either idiopathic or associated with other inflammatory diseases. Testing the hypothesis: We consecutively enrolled 25 patients (19 pediatric and 6 adults) affected with ACU. For each patient medical history was reviewed and clinical data were recorded. Allelic and genotypic frequencies of NOD2/CARD15 variations were calculated in patients and matched with those of 25 healthy controls. The statistical analysis was performed. Fifteen patients showed the polymorphism P268S/SNP5 (SNP rs2066842) as heterozygous carriers while two patients were homozygous for the same polymorphism; one patient carried also the variant c647 18-16 TCT on intron 3, not previously reported in the literature. Statistical analysis for NOD2/CARD15 genotyping showed significant differences between patients and controls for allelic frequencies (p=0.04, OR: 4.03, 95 %; CI=1.2-13.5) but not for genotypic frequencies. We could not identify a significant phenotype-genotype correlation. Implications of the hypothesis: In our cohort of Italian patients, the NOD2/CARD15 common variant P268S/SNP5 could potentially be significantly associated with ACU
Tunable Electron Multibunch Production in Plasma Wakefield Accelerators
Synchronized, independently tunable and focused J-class laser pulses are
used to release multiple electron populations via photo-ionization inside an
electron-beam driven plasma wave. By varying the laser foci in the laboratory
frame and the position of the underdense photocathodes in the co-moving frame,
the delays between the produced bunches and their energies are adjusted. The
resulting multibunches have ultra-high quality and brightness, allowing for
hitherto impossible bunch configurations such as spatially overlapping bunch
populations with strictly separated energies, which opens up a new regime for
light sources such as free-electron-lasers
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