3,207 research outputs found

    Jets and Jet Multiplicities in High Energy Photon-Nucleon Inetraction:

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    We discuss the theory of jet events in high-energy photon-proton interactions using a model which gives a good description of the data available on total inelastic γp\gamma p cross sections up to s\sqrt{s}=210 GeV. We show how to calculate the jet cross sections and jet multiplicities and give predictions for these quantities for energies appropriate for experiments at the HERA epep collider and for very high energy cosmic ray observations.Comment: 12 pages + 4 figs, MAD/TH/92-8, submitted to Phys. Rev. D(Rapid Communications), figs. available on request from [email protected]

    Diffraction-limited Subaru imaging of M82: sharp mid-infrared view of the starburst core

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    We present new imaging at 12.81 and 11.7 microns of the central ~40"x30" (~0.7x0.5 kpc) of the starburst galaxy M82. The observations were carried out with the COMICS mid-infrared (mid-IR) imager on the 8.2m Subaru telescope, and are diffraction-limited at an angular resolution of <0".4. The images show extensive diffuse structures, including a 7"-long linear chimney-like feature and another resembling the edges of a ruptured bubble. This is the clearest view to date of the base of the kpc-scale dusty wind known in this galaxy. These structures do not extrapolate to a single central point, implying multiple ejection sites for the dust. In general, the distribution of dust probed in the mid-IR anticorrelates with the locations of massive star clusters that appear in the near-infrared. The 10-21 micron mid-IR emission, spatially-integrated over the field of view, may be represented by hot dust with temperature of ~160 K. Most discrete sources are found to have extended morphologies. Several radio HII regions are identified for the first time in the mid-IR. The only potential radio supernova remnant to have a mid-IR counterpart is a source which has previously also been suggested to be a weak active galactic nucleus. This source has an X-ray counterpart in Chandra data which appears prominently above 3 keV and is best described as a hot (~2.6 keV) absorbed thermal plasma with a 6.7 keV Fe K emission line, in addition to a weaker and cooler thermal component. The mid-IR detection is consistent with the presence of strong [NeII]12.81um line emission. The broad-band source properties are complex, but the X-ray spectra do not support the active galactic nucleus hypothesis. We discuss possible interpretations regarding the nature of this source.Comment: Accepted for publication in PASJ Subaru special issue. High resolution version available temporarily at http://www.astro.isas.jaxa.jp/~pgandhi/pgandhi_m82.pd

    New Reports of Exotic and Native Ambrosia and Bark Beetle Species (Coleoptera: Curculionidae: Scolytinae) From Ohio

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    In a 2007 survey of ambrosia and bark beetles (Coleoptera: Curculionidae: Scolytinae) along a transect in northeastern Ohio, we collected six exotic and three native species not previously reported from the state. These species include the exotic ambrosia beetles Ambrosiodmus rubricollis (Eichhoff), Dryoxylon onoharaensum (Murayama), Euwallacea validus (Eichhoff), Xyleborus californicus Wood, Xyleborus pelliculosusEichhoff, and Xylosandrus crassiusculus (Motschulsky). The native ambrosia beetle Corthylus columbianus Hopkins, and the native bark beetles Dryocoetes autographus (Ratzeburg) and Hylastes tenuis Eichhoff are also reported from Ohio for the first time. Our study suggests a northward range expansion for five of the six exotic species including, X. crassiusculus, which is an important pest of nursery and orchard crops in the southeastern United States

    High-energy Atmospheric Muon Flux Expected at India-Based Neutrino Observatory

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    We calculate the zenith-angle dependence of conventional and prompt high-energy muon fluxes at India-Based Neutrino Observatory (INO) depth. This study demonstrates a possibility to discriminate models of the charm hadroproduction including the low-x QCD behaviour of hadronic cross-sections relevant at very high energies.Comment: 10 pages. 8 figures, 3 table

    TeV Strings and the Neutrino-Nucleon Cross Section at Ultra-high Energies

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    In scenarios with the fundamental unification scale at the TeV one expects string excitations of the standard model fields at accessible energies. We study the neutrino-nucleon cross section in these models. We show that duality of the scattering amplitude forces the existence of a tower of massive leptoquarks that mediate the process in the s-channel. Using the narrow-width approximation we find a sum rule for the production rate of resonances with different spin at each mass level. We show that these contributions can increase substantially the standard model neutrino-nucleon cross section, although seem insufficient in order to explain the cosmic ray events above the GZK cutoff energy.Comment: 10 pages, 1 figure, version to appear in PR

    An Advanced Real Time Lead RF-MEMS Based Switch Design for AI Applications

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    The artificial intelligence-based MEMS switch designs have been led technology in present micro-electronic applications. The 4G and 5G communication hardware networks have working been through RF-MEMS switches. The earlier MEMS deigns are outdated in terms of functionality and compatibility, so that a realistic RF-MEMS based advanced configurations are compulsory for future electronic applications. In this research work 2 different shunt-capacitive type configurations have been implemented and those are verified on COMSOL Multi-physics toolbox as well as functionality been verified on HFSS software tool. The electromechanical properties of proposed shunt type RF-MEMS switch attained more perfection in functionality compared to past configurations. The implemented switching model has uniform meandering and derives pull-in-voltage of 18.5v along with 1.2xs switching time. The 2nd type shunt RF-MEMS model has been generated pull-in-voltage of 25.5v and isolation loss of 37.20.  The performance metrics like Length 25.34 µm, Width 28.92 µm and Thickness 34.42 µm had been improved compared to previous models. The deigned shunt-capacitive type RF-MEMS models are most prominent in operation and offering advanced microelectronics applications

    An Advanced Real Time Lead RF-MEMS Based Switch Design for AI Applications

    Get PDF
    The artificial intelligence-based MEMS switch designs have been led technology in present micro-electronic applications. The 4G and 5G communication hardware networks have working been through RF-MEMS switches. The earlier MEMS deigns are outdated in terms of functionality and compatibility, so that a realistic RF-MEMS based advanced configurations are compulsory for future electronic applications. In this research work 2 different shunt-capacitive type configurations have been implemented and those are verified on COMSOL Multi-physics toolbox as well as functionality been verified on HFSS software tool. The electromechanical properties of proposed shunt type RF-MEMS switch attained more perfection in functionality compared to past configurations. The implemented switching model has uniform meandering and derives pull-in-voltage of 18.5v along with 1.2xs switching time. The 2nd type shunt RF-MEMS model has been generated pull-in-voltage of 25.5v and isolation loss of 37.20.  The performance metrics like Length 25.34 µm, Width 28.92 µm and Thickness 34.42 µm had been improved compared to previous models. The deigned shunt-capacitive type RF-MEMS models are most prominent in operation and offering advanced microelectronics applications

    Prospecting Period Measurements with LSST - Low Mass X-ray Binaries as a Test Case

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    The Large Synoptic Survey Telescope (LSST) will provide for unbiased sampling of variability properties of objects with rr mag << 24. This should allow for those objects whose variations reveal their orbital periods (PorbP_{orb}), such as low mass X-ray binaries (LMXBs) and related objects, to be examined in much greater detail and with uniform systematic sampling. However, the baseline LSST observing strategy has temporal sampling that is not optimised for such work in the Galaxy. Here we assess four candidate observing strategies for measurement of PorbP_{orb} in the range 10 minutes to 50 days. We simulate multi-filter quiescent LMXB lightcurves including ellipsoidal modulation and stochastic flaring, and then sample these using LSST's operations simulator (OpSim) over the (mag, PorbP_{orb}) parameter space, and over five sightlines sampling a range of possible reddening values. The percentage of simulated parameter space with correctly returned periods ranges from ∼\sim23 %, for the current baseline strategy, to ∼\sim70 % for the two simulated specialist strategies. Convolving these results with a PorbP_{orb} distribution, a modelled Galactic spatial distribution and reddening maps, we conservatively estimate that the most recent version of the LSST baseline strategy will allow PorbP_{orb} determination for ∼\sim18 % of the Milky Way's LMXB population, whereas strategies that do not reduce observations of the Galactic Plane can improve this dramatically to ∼\sim32 %. This increase would allow characterisation of the full binary population by breaking degeneracies between suggested PorbP_{orb} distributions in the literature. Our results can be used in the ongoing assessment of the effectiveness of various potential cadencing strategies.Comment: Replacement after addressing minor corrections from the referee - mainly improvements in clarificatio
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