1,297 research outputs found
Scaling in directed dynamical small-world networks with random responses
A dynamical model of small-world network, with directed links which describe
various correlations in social and natural phenomena, is presented. Random
responses of every site to the imput message are introduced to simulate real
systems. The interplay of these ingredients results in collective dynamical
evolution of a spin-like variable S(t) of the whole network. In the present
model, global average spreading length \langel L >_s and average spreading time
_s are found to scale as p^-\alpha ln N with different exponents.
Meanwhile, S behaves in a duple scaling form for N>>N^*: S ~ f(p^-\beta
q^\gamma t'_sc), where p and q are rewiring and external parameters, \alpha,
\beta, \gamma and f(t'_sc) are scaling exponents and universal functions,
respectively. Possible applications of the model are discussed.Comment: 4 pages, 6 Figure
Hybrid hierarchical clustering: piecewise aggregate approximation, with applications
Piecewise Aggregate Approximation (PAA) provides a powerful yet computationally efficient tool for dimensionality reduction and feature extraction on large datasets compared to previously reported and well-used feature extraction techniques, such as Principal Component Analysis (PCA). Nevertheless, performance can degrade as a result of either regional information insufficiency or over-segmentation, and because of this, additional relatively complex modifications have subsequently been reported, for instance, Adaptive Piecewise Constant Approximation (APCA). To recover some of the simplicity of the original PAA, whilst addressing the known problems, a distance-based Hierarchical Clustering (HC) technique is now proposed to adjust PAA segment frame sizes to focus segment density on information rich data regions. The efficacy of the resulting hybrid HC-PAA methodology is demonstrated using two application case studies on non-time-series data viz. fault detection on industrial gas turbines, and ultrasonic biometric face identification. Pattern recognition results show that the extracted features from the hybrid HC-PAA provide additional benefits with regard to both cluster separation and classification performance, compared to traditional PAA and the APCA alternative. The method is therefore demonstrated to provide a robust readily implemented algorithm for rapid feature extraction and identification for datasets
The Presence of Conspecific Decoys Enhances the Attractiveness of an NaCl Resource to the Yellow-Spined Locust, Ceracris kiangsu
Adults of the yellow-spined bamboo locust, Ceracris kiangsu Tsai (Orthoptera: Oedipodidae), aggregate and gnaw at human urine-contaminated materials, a phenomenon termed puddling. Several urine-borne chemicals, including NaCl, are known to stimulate adult C. kiangsu to consume filter paper. Because in nature C. kiangsu adults may use cues to locate puddling resources, we tested the influence of conspecific decoys (dried C. kiangsu) on foraging and consumption of 3% NaCl—treated filter paper. In a two—choice test experiment in the laboratory, female adults showed no preference for filter papers (not treated with NaCL) with or without decoys. In contrast, C. kiangsu females consumed significantly more NaCl—treated filter paper on which conspecific decoys were attached than those without decoys in both the laboratory and in a bamboo forest. When the bait was changed to 3% NaCl plus the insecticide bisultap, significantly more C. kiangsu were killed in the bamboo forest when decoys were present, however the results were not significant when the experiment was done in the laboratory. Hence, moving towards conspecifics seems to facilitate NaCl resource foraging in C. kiangsu, suggesting that the presence of conspecifics promotes feeding on puddling resources
Simulations of Infrared Radiances Over a Deep Convective Cloud System Observed During TC4: Potential for Enhancing Nocturnal Ice Cloud Retrievals
Retrievals of ice cloud properties using infrared measurements at 3.7, 6.7, 7.3, 8.5, 10.8, and 12.0 microns can provide consistent results regardless of solar illumination, but are limited to cloud optical thicknesses tau 20, the 3.7 - 10.8 microns and 3.7 - 6.7 microns BTDs are the most sensitive to D(sub e). Satellite imagery appears consistent with these results. Keywords: clouds; optical depth; particle size; satellite; TC4; multispectral thermal infrare
Observation of eight-photon entanglement
Using ultra-bright sources of pure-state entangled photons from parametric
down conversion, an eight-photon interferometer and post-selection detection,
we demonstrate the ability to experimentally manipulate eight individual
photons and report the creation of an eight-photon Schr\"odinger cat state with
an observed fidelity of .Comment: 6 pages, 4 figure
Nuclear pore protein NUP210 depletion suppresses metastasis through heterochromatin-mediated disruption of tumor cell mechanical response.
Mechanical signals from the extracellular microenvironment have been implicated in tumor and metastatic progression. Here, we identify nucleoporin NUP210 as a metastasis susceptibility gene for human estrogen receptor positive (ER+) breast cancer and a cellular mechanosensor. Nup210 depletion suppresses lung metastasis in mouse models of breast cancer. Mechanistically, NUP210 interacts with LINC complex protein SUN2 which connects the nucleus to the cytoskeleton. In addition, the NUP210/SUN2 complex interacts with chromatin via the short isoform of BRD4 and histone H3.1/H3.2 at the nuclear periphery. In Nup210 knockout cells, mechanosensitive genes accumulate H3K27me3 heterochromatin modification, mediated by the polycomb repressive complex 2 and differentially reposition within the nucleus. Transcriptional repression in Nup210 knockout cells results in defective mechanotransduction and focal adhesion necessary for their metastatic capacity. Our study provides an important role of nuclear pore protein in cellular mechanosensation and metastasis
Biventricular Increases in Mitochondrial Fission Mediator (MiD51) and Proglycolytic Pyruvate Kinase (PKM2) Isoform in Experimental Group 2 Pulmonary Hypertension-Novel Mitochondrial Abnormalities
Introduction: Group 2 pulmonary hypertension (PH), defined as a mean pulmonary arterial pressure ≥25 mmHg with elevated pulmonary capillary wedge pressure >15 mmHg, has no approved therapy and patients often die from right ventricular failure (RVF). Alterations in mitochondrial metabolism, notably impaired glucose oxidation, and increased mitochondrial fission, contribute to right ventricle (RV) dysfunction in PH. We hypothesized that the impairment of RV and left ventricular (LV) function in group 2 PH results in part from a proglycolytic isoform switch from pyruvate kinase muscle (PKM) isoform 1 to 2 and from increased mitochondrial fission, due either to upregulation of expression of dynamin-related protein 1 (Drp1) or its binding partners, mitochondrial dynamics protein of 49 or 51 kDa (MiD49 or 51).Methods and Results: Group 2 PH was induced by supra-coronary aortic banding (SAB) in 5-week old male Sprague Dawley rats. Four weeks post SAB, echocardiography showed marked reduction of tricuspid annular plane systolic excursion (2.9 ± 0.1 vs. 4.0 ± 0.1 mm) and pulmonary artery acceleration time (24.3 ± 0.9 vs. 35.4 ± 1.8 ms) in SAB vs. sham rats. Nine weeks post SAB, left and right heart catheterization showed significant biventricular increases in end systolic and diastolic pressure in SAB vs. sham rats (LV: 226 ± 15 vs. 103 ± 5 mmHg, 34 ± 5 vs. 7 ± 1 mmHg; RV: 40 ± 4 vs. 22 ± 1 mmHg, and 4.7 ± 1.5 vs. 0.9 ± 0.5 mmHg, respectively). Picrosirius red staining showed marked biventricular fibrosis in SAB rats. There was increased muscularization of small pulmonary arteries in SAB rats. Confocal microscopy showed biventricular mitochondrial depolarization and fragmentation in SAB vs. sham cardiomyocytes. Transmission electron microscopy confirmed a marked biventricular reduction in mitochondria size in SAB hearts. Immunoblot showed marked biventricular increase in PKM2/PKM1 and MiD51 expression. Mitofusin 2 and mitochondrial pyruvate carrier 1 were increased in SAB LVs.Conclusions: SAB caused group 2 PH. Impaired RV function and RV fibrosis were associated with increases in mitochondrial fission and expression of MiD51 and PKM2. While these changes would be expected to promote increased production of reactive oxygen species and a glycolytic shift in metabolism, further study is required to determine the functional consequences of these newly described mitochondrial abnormalities
A Unified Approach to the Classical Statistical Analysis of Small Signals
We give a classical confidence belt construction which unifies the treatment
of upper confidence limits for null results and two-sided confidence intervals
for non-null results. The unified treatment solves a problem (apparently not
previously recognized) that the choice of upper limit or two-sided intervals
leads to intervals which are not confidence intervals if the choice is based on
the data. We apply the construction to two related problems which have recently
been a battle-ground between classical and Bayesian statistics: Poisson
processes with background, and Gaussian errors with a bounded physical region.
In contrast with the usual classical construction for upper limits, our
construction avoids unphysical confidence intervals. In contrast with some
popular Bayesian intervals, our intervals eliminate conservatism (frequentist
coverage greater than the stated confidence) in the Gaussian case and reduce it
to a level dictated by discreteness in the Poisson case. We generalize the
method in order to apply it to analysis of experiments searching for neutrino
oscillations. We show that this technique both gives correct coverage and is
powerful, while other classical techniques that have been used by neutrino
oscillation search experiments fail one or both of these criteria.Comment: 40 pages, 15 figures. Changes 15-Dec-99 to agree more closely with
published version. A few small changes, plus the two substantive changes we
made in proof back in 1998: 1) The definition of "sensitivity" in Sec. V(C).
It was inconsistent with our actual definition in Sec. VI. 2) "Note added in
proof" at end of the Conclusio
Observation of Y(2175) in
The decays of are analyzed using a sample of events collected with the BESII detector at the Beijing
Electron-Positron Collider (BEPC). A structure at around GeV/ with
about significance is observed in the invariant mass
spectrum. A fit with a Breit-Wigner function gives the peak mass and width of
GeV/ and GeV/, respectively, that are consistent with those
of Y(2175), observed by the BABAR collaboration in the initial-state radiation
(ISR) process . The production branching
ratio is determined to be , assuming that the Y(2175) is a state.Comment: 5 pages, 4 figures, accepted by Phys. Rev. Let
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