17,881 research outputs found

    The GeV-TeV Connection in Galactic gamma-ray sources

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    Recent observations with atmospheric Cherenkov telescope systems such as H.E.S.S. and MAGIC have revealed a large number of new sources of very-high-energy (VHE) gamma-rays from 100 GeV - 100 TeV, mostly concentrated along the Galactic plane. At lower energies (100 MeV - 10 GeV) the satellite-based instrument EGRET revealed a population of sources clustering along the Galactic Plane. Given their adjacent energy bands a systematic correlation study between the two source catalogues seems appropriate. Here, the populations of Galactic sources in both energy domains are characterised on observational as well as on phenomenological grounds. Surprisingly few common sources are found in terms of positional coincidence and spectral consistency. These common sources and their potential counterparts and emission mechanisms will be discussed in detail. In cases of detection only in one energy band, for the first time consistent upper limits in the other energy band have been derived. The EGRET upper limits are rather unconstraining due to the sensitivity mismatch to current VHE instruments. The VHE upper limits put strong constraints on simple power-law extrapolation of several of the EGRET spectra and thus strongly suggest cutoffs in the unexplored energy range from 10 GeV - 100 GeV. Physical reasons for the existence of cutoffs and for differences in the source population at GeV and TeV energies will be discussed. Finally, predictions will be derived for common GeV - TeV sources for the upcoming GLAST mission bridging for the first time the energy gap between current GeV and TeV instruments.Comment: (1) Kavli Institute for Particle Astrophysics and Cosmology (KIPAC), Stanford, USA (2) Stanford University, W.W. Hansen Experimental Physics Lab (HEPL) and KIPAC, Stanford, USA (3) ICREA & Institut de Ciencies de l'Espai (IEEC-CSIC) Campus UAB, Fac. de Ciencies, Barcelona, Spain. (4) School of Physics and Astronomy, University of Leeds, UK. Paper Submitted to Ap

    Front-End electronics configuration system for CMS

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    The four LHC experiments at CERN have decided to use a commercial SCADA (Supervisory Control And Data Acquisition) product for the supervision of their DCS (Detector Control System). The selected SCADA, which is therefore used for the CMS DCS, is PVSS II from the company ETM. This SCADA has its own database, which is suitable for storing conventional controls data such as voltages, temperatures and pressures. In addition, calibration data and FE (Front-End) electronics configuration need to be stored. The amount of these data is too large to be stored in the SCADA database [1]. Therefore an external database will be used for managing such data. However, this database should be completely integrated into the SCADA framework, it should be accessible from the SCADA and the SCADA features, e.g. alarming, logging should be benefited from. For prototyping, Oracle 8i was selected as the external database manager. The development of the control system for calibration constants and FE electronics configuration has been done in close collaboration with the CMS tracker group and JCOP (Joint COntrols Project)(1). (1)The four LHC experiments and the CERN IT/CO group has merged their efforts to build the experiments controls systems and set up the JCOP at the end of December, 1997 for this purpose.Comment: 3 pages, 4 figures, Icaleps'01 conference PSN WEDT00

    \u3ci\u3eAcrobasis\u3c/i\u3e Shoot Moth (Lepidoptera: Pyralidae) Infestation-Tree Height Link in a Young Black Walnut Plantation

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    Acrobasis shoot moth infestations were evaluated in a young black walnut progeny test for 4 years, from ages 3 to 6. Infestation levels were greatest on the largest trees in the fourth and fifth year after plantation establishment, and were declining by the sixth year. Acrobasis infestation appears to be a problem primarily on young trees less than 2.5 m in height. There was no evidence for genetic resistance to Acrobasis infestation in black walnut

    Laser net - A concept for monitoring wingtip vortices on runways

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    Network of laser beams passes over runway to photodetectors on opposite side, magnitude of beam deflection indicates magnitude of density gradient encountered. Visual display of beam deflections affects go, no-go decision for takeoff and landing

    Fermi Detection of the Pulsar Wind Nebula HESS J1640-465

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    We present observations of HESS J1640-465 with the Fermi-LAT. The source is detected with high confidence as an emitter of high-energy gamma-rays. The spectrum lacks any evidence for the characteristic cutoff associated with emission from pulsars, indicating that the emission arises primarily from the pulsar wind nebula. Broadband modeling implies an evolved nebula with a low magnetic field resulting in a high gamma-ray to X-ray flux ratio. The Fermi emission exceeds predictions of the broadband model, and has a steeper spectrum, possibly resulting from a distinct excess of low energy electrons similar to what is inferred for both the Vela X and Crab pulsar wind nebulae.Comment: 6 pages, 5 figures, accepted for publication in Ap

    Muscular dystrophy meets protein biochemistry, the mother of invention

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    Muscular dystrophies result from a defect in the linkage between the muscle fiber cytoskeleton and the basement membrane (BM). Congenital muscular dystrophy type MDC1A is caused by mutations in laminin α2 that either reduce its expression or impair its ability to polymerize within the muscle fiber BM. Defects in this BM lead to muscle fiber damage from the force of contraction. In this issue of the JCI, McKee and colleagues use a laminin polymerization–competent, designer chimeric BM protein in vivo to restore function of a polymerization-defective laminin, leading to normalized muscle structure and strength in a mouse model of MDC1A. Delivery of such a protein to patients could ameliorate many aspects of their disease

    AN ECONOMIC ANALYSIS OF A CORN-SOYBEAN CROP ROTATION UNDER VARIOUS INPUT COMBINATIONS IN SOUTH CENTRAL TEXAS

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    Eight input combinations of commercial fertilizer, insecticides, and herbicides on a corn-soybean crop rotation in the Brazos River Bottom of Texas are evaluated. Input combinations which do not fully utilize all three inputs are consistently ranked higher by all criteria as the preferred input strategy for the corn-soybean rotation system. These results, which indicate limited input crop rotations that fall somewhere between the extremes of conventional agricultural production and organic agriculture, deserve further attention as a possible production alternative.corn, limited input, soybean, Crop Production/Industries,

    Inducible arginase 1 deficiency in mice leads to hyperargininemia and altered amino acid metabolism

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    Arginase deficiency is a rare autosomal recessive disorder resulting from a loss of the liver arginase isoform, arginase 1 (ARG1), which is the final step in the urea cycle for detoxifying ammonia. ARG1 deficiency leads to hyperargininemia, characterized by progressive neurological impairment, persistent growth retardation and infrequent episodes of hyperammonemia. Using the Cre/loxP-directed conditional gene knockout system, we generated an inducible Arg1-deficient mouse model by crossing "floxed" Arg1 mice with CreER(T2) mice. The resulting mice (Arg-Cre) die about two weeks after tamoxifen administration regardless of the starting age of inducing the knockout. These treated mice were nearly devoid of Arg1 mRNA, protein and liver arginase activity, and exhibited symptoms of hyperammonemia. Plasma amino acid analysis revealed pronounced hyperargininemia and significant alterations in amino acid and guanidino compound metabolism, including increased citrulline and guanidinoacetic acid. Despite no alteration in ornithine levels, concentrations of other amino acids such as proline and the branched-chain amino acids were reduced. In summary, we have generated and characterized an inducible Arg1-deficient mouse model exhibiting several pathologic manifestations of hyperargininemia. This model should prove useful for exploring potential treatment options of ARG1 deficiency
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