4,648 research outputs found
Order statistics of 1/f^{\alpha} signals
Order statistics of periodic, Gaussian noise with 1/f^{\alpha} power spectrum
is investigated. Using simulations and phenomenological arguments, we find
three scaling regimes for the average gap d_k= between the k-th
and (k+1)-st largest values of the signal. The result d_k ~ 1/k known for
independent, identically distributed variables remains valid for 0<\alpha<1.
Nontrivial, \alpha-dependent scaling exponents d_k ~ k^{(\alpha -3)/2} emerge
for 1<\alpha<5 and, finally, \alpha-independent scaling, d_k ~ k is obtained
for \alpha>5. The spectra of average ordered values \epsilon_k= ~
k^{\beta} is also examined. The exponent {\beta} is derived from the gap
scaling as well as by relating \epsilon_k to the density of near extreme
states. Known results for the density of near extreme states combined with
scaling suggest that \beta(\alpha=2)=1/2, \beta(4)=3/2, and beta(infinity)=2
are exact values. We also show that parallels can be drawn between \epsilon_k
and the quantum mechanical spectra of a particle in power-law potentials.Comment: 8 pages, 5 figure
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Integrated Solar Technologies with Outdoor Pedestrian Bridge Superstructure Decking
Solar technology has been a major topic in sustainable design for many years. In the last five years, however, the solar technology industry has seen a rapid growth in installations and technological advances in cell design. Combined with a rapidly declining overall system cost, the idea of introducing solar technology into a wider range of applications is becoming a focus for engineers and scientists around the world. So many variables which alter solar energy production, such as the sun and surrounding environment, determine whether a solar design is beneficial. This thesis presents a bridge deck surface integrated with solar cells tested under all AASHTO LRFD pedestrian bridge loadings. A detailed solar analysis of the University of Massachusetts’s campus is presented to determine if solar integration is even plausible for the Northeastern United States with the energy limitations created by the deck integration, as well as an economic evaluation of the deck design. The purpose of this thesis was to determine if a walking surface could be integrated with solar technology and be a plausible alternative to conventional walking surfaces, while providing a source of sustainable power
Maxwell Fields in Spacetimes Admitting Non-Null Killing Vectors
We consider source-free electromagnetic fields in spacetimes possessing a
non-null Killing vector field, . We assume further that the
electromagnetic field tensor, , is invariant under the action of the
isometry group induced by . It is proved that whenever the two
potentials associated with the electromagnetic field are functionally
independent the entire content of Maxwell's equations is equivalent to the
relation \n^aT_{ab}=0. Since this relation is implied by Einstein's equation
we argue that it is enough to solve merely Einstein's equation for these
electrovac spacetimes because the relevant equations of motion will be
satisfied automatically. It is also shown that for the exceptional case of
functionally related potentials \n^aT_{ab}=0 implies along with one of the
relevant equations of motion that the complementary equation concerning the
electromagnetic field is satisfied.Comment: 7 pages,PACS numbers: 04.20.Cv, 04.20.Me, 04.40.+
Új módszertani lehetőségek és ezek alkalmazása a hormonális rendszer daganatainak genetikai kivizsgálásában
The technical developments leading to revolution in clinical genetic testing offer new approaches for patients with cancer. From one mutation or one gene approach the scale of genetic testing moved to whole exome or whole genome scale. It is well known that many tumours are genetically determined ans they are part of familial tumour syndromes. In addition, some mutations indicate specific molecular targeted therapies. Although sampling and sample preparation are different for testing germline and somatic mutations, the technical background of the analysis is the same. The aim of clinical genetic testing is to identify patients who are carriers of disease-causing mutations or to test tumour tissue for the presence of genetic alterations which may be targets for therapeutic approaches. In this review the authors summarize novel possibilities offered by next-generation sequencing in clinical genetic testing of patients with endocrine tumours. In addition, the authors review recent guidelines on technical and ethical issues related to these novel methods. Orv. Hetil., 2015, 156(51), 2063-2069
CD4 T cells remain the major source of HIV-1 during end stage disease.
OBJECTIVE: To assess the source of HIV-1 production in lymphoid tissue biopsies from HIV-infected patients, with no prior anti-retroviral protease inhibitor treatment, with a CD4 cell count > 150 x 10(6)/l (group I) or < 50 x 10(6)/l (group II), co-infected with Mycobacterium tuberculosis or Mycobacterium avium complex. DESIGN AND METHODS: Lymphoid tissue biopsies from 11 HIV-1-infected patients, taken for diagnostic purposes, were studied by HIV-1 RNA in situ hybridization and immunohistochemistry. RESULTS: Patients of group I showed well organized granulomas, in contrast with patients of group II, in which granuloma formation was absent. HIV-1 RNA-positive cells in group I patients were found mainly around the granulomas, whereas in group II HIV-1-producing cells were confined to areas with remaining intact lymphoid tissue. Despite the abundant presence of macrophages, the productively infected HIV-1-positive cells in both groups were almost exclusively CD4 T cells. CONCLUSION: In contrast with previously published data, CD4 T cells appear to remain the major source of HIV-1 production in end-stage disease
Distribution of Maximal Luminosity of Galaxies in the Sloan Digital Sky Survey
Extreme value statistics (EVS) is applied to the distribution of galaxy luminosities in the Sloan Digital Sky Survey (SDSS). We analyze the DR8 Main Galaxy Sample (MGS), as well as the Luminous Red Galaxies (LRG). Maximal luminosities are sampled from batches consisting of elongated pencil beams in the radial direction of sight. For the MGS, results suggest a small and positive tail index , effectively ruling out the possibility of having a finite maximum cutoff luminosity, and implying that the luminosity distribution function may decay as a power law at the high luminosity end. Assuming, however, , a non-parametric comparison of the maximal luminosities with the Fisher-Tippett-Gumbel distribution (limit distribution for variables distributed by the Schechter fit) indicates a good agreement provided uncertainties arising both from the finite batch size and from the batch size distribution are accounted for. For a volume limited sample of LRGs, results show that they can be described as being the extremes of a luminosity distribution with an exponentially decaying tail, provided the uncertainties related to batch-size distribution are taken care of
Broadening of coreceptor usage by human immunodeficiency virus type 2 does not correlate with increased pathogenicity in an in vivo model.
The pathogenic properties of four primary human immunodeficiency virus type 2 (HIV-2) isolates and two primary HIV-2 biological clones were studied in an in vivo human-to-mouse chimeric model. The cell-associated viral load and the ability to reduce the severity of the induced graft-versus-host disease symptoms, the CD4/CD8 ratio and the level of repopulation of the mouse tissues by the graft, were determined. All HIV-2 strains, irrespective of their in vitro biological phenotype, replicated to high titres and significantly reduced graft-versus-host disease symptoms as well as the CD4/CD8 ratios. Reduction of graft repopulation caused by infection with the respective HIV-2 strains showed that the in vitro replication rate, syncytium-inducing capacity and ability to infect human macrophages did influence the in vivo pathogenic potential whereas broadening of coreceptor usage did not
Action and Hamiltonian for eternal black holes
We present the Hamiltonian, quasilocal energy, and angular momentum for a
spacetime region spatially bounded by two timelike surfaces. The results are
applied to the particular case of a spacetime representing an eternal black
hole. It is shown that in the case when the boundaries are located in two
different wedges of the Kruskal diagram, the Hamiltonian is of the form , where and are the Hamiltonian functions for the right
and left wedges respectively. The application of the obtained results to the
thermofield dynamics description of quantum effects in black holes is briefly
discussed.Comment: 24 pages, Revtex, 5 figures (available upon request
Mechanisms of THz generation from silver nanoparticle and nanohole arrays illuminated by 100 fs pulses of infrared light
Copyright © 2014 American Physical SocietyWe study THz pulses generated from plasmonic metal nanostructures under femtosecond illumination of near-IR light. We find two regimes of excitation, according to the order of the dependence of the THz fluence on the incident near-IR intensity: less then second order at low intensities, changing to approximately fourth order for higher intensities. These regimes are most likely associated with two THz generation mechanisms: optical rectification, and the ponderomotive acceleration of ejected electrons. These data provide evidence that both mechanisms can be at work in the same experiment.Hungarian Scientific Research FundBolyai FellowshipPostdoctoral Fellowship of the Hungarian Academy of SciencesMarie Curie Fellowship of the EU (project acronym `UPNEX'
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