1,366 research outputs found

    511 keV γ\gamma-ray emission from the galactic bulge by MeV millicharged dark matter

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    We propose a possible explanation for the recently observed anomalous 511 keV line with a new "millicharged" fermion. This new fermion is light [O(MeV){\cal O}({\rm MeV})]. Nevertheless, it has never been observed by any collider experiments by virtue of its tiny electromagnetic charge ϵe\epsilon e. In particular, we constrain parameters of this millicharged particle if the 511 keV cosmic γ\gamma-ray emission from the galactic bulge is due to positron production from this new particle.Comment: 3 pages, 1 figure, A talk given by J.C.Park at the 16th International Conference on Supersymmetry and the Unification of Fundamental Interactions (SUSY08), Seoul, Korea, June 16-21, 200

    Performance and Fouling in Pre-Denitrification Membrane Bioreactors Treating High-Strength Wastewater from Food Waste Disposers

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    The study investigated the performance of the pre-denitrification membrane bioreactor (MBR) process to treat high-strength wastewater generated from food waste disposals. Extracellular polymeric substances (EPS) as membrane foulant and microbial community profiles were analyzed under different hydraulic retention time (HRT) operation conditions. The pre-denitrification MBR was effective for treating food wastewater with high chemical oxygen demand (COD)/N resulting in high total nitrogen (TN) removal efficiency. The operational data showed that effluent qualities in terms of COD, TN, and TP improved with longer HRT. However, membrane fouling potential as shown by specific membrane fouling rate and specific resistance to filtration (SRF) increased as HRT increased. The longer HRT conditions or lower influent loading led to higher levels of bound EPS while HRT did not show large effects on the level of soluble microbial products (SMP). The restriction fragment length polymorphism (RFLP) analysis showed similar microbial banding patterns from the sludges generated under different HRT conditions, indicating that HRT had minimal effects on the composition of microbial communities in the system. All these results suggest that the MBR with pre-denitrification is a feasible option for treating high-strength food wastewater and that different HRT conditions could affect the operational performance and the fouling rate, which is governed via changes in microbial responses through EPS in the system

    Production of Transgenic Cloned Miniature Pigs with Membrane-bound Human Fas Ligand (FasL) by Somatic Cell Nuclear Transfer

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    Cell-mediated xenograft rejection, including NK cells and CD8+ CTL, is a major obstacle in successful pig-to-human xenotransplantation. Human CD8+ CTL and NK cells display high cytotoxicity for pig cells, mediated at least in part by the Fas/FasL pathway. To prevent cell-mediated xenocytotoxicity, a membrane-bound form of human FasL (mFasL) was generated as an inhibitor for CTL and NK cell cytotoxicity that could not be cleaved by metalloproteinase to produce putative soluble FasL. We produced two healthy transgenic pigs harboring the mFasL gene via somatic cell nuclear transfer (SCNT). In a cytotoxicity assay using transgenic clonal cell lines and transgenic pig ear cells, the rate of CD8+ CTL-mediated cytotoxicity was significantly reduced in transgenic pig's ear cells compared with that in normal minipig fetal fibroblasts. Our data indicate that grafts of transgenic pigs expressing membrane-bound human FasL control the cellular immune response to xenografts, creating a window of opportunity to facilitate xenograft survival

    CONTRIBUTION OF THE KNEE JOINT TO MECHANICAL ENERGY IN CROUCHING START ACCORDING TO THE BACKWARD BLOCK INCLINED ANGLE INCREASE

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    The purpose of this study was to analyze the contribution of the knee joint to mechanical energy in crouching start according to the backward block inclined angle increase(F, F1, F2). Using kinetic and kinematic data from 3 university sprinters participating in this study we calculated the energies absorbed and generated by the knee joints. The analysis is limited to a two-dimensional (sagittal plane) exercise. Comparing mean values of the energy absorbed and generated from lower extremity joints of each subjects according to backward block inclined angle increase (F, F1, F2). We generate a ratio of a total energy absorbed and generated from lower extremities to one from knee joints. The generated energy of knee joints during start was the highest for all subjects and the absorbed energy of those was the lowest at 55 degree of backward block angle, or F, for subject 1, 50 degree for subject 2, and 50 degree for subject 3

    Ability of Stratus OCT to identify localized retinal nerve fiber layer defects in patients with normal standard automated perimetry results

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    PURPOSE: To evaluate the ability of Stratus optical coherence tomography (OCT; Carl Zeiss Meditec, Dublin, CA) with its internal normative database to discriminate between healthy eyes and eyes with a localized retinal nerve fiber layer (RNFL) defect not accompanied by a perimetric defect according to standard automated perimetry (SAP) (i.e., a preperimetric localized RNFL defect). METHODS: Data were retrospectively reviewed from 49 eyes of 49 subjects with preperimetric localized RNFL defects, and 49 healthy control eyes of 49 age-matched subjects, with classification into each group based primarily on red-free fundus photography RESULTS: The sensitivity and specificity of various OCT RNFL thickness parameters for identifying subjects with preperimetric localized RNFL defects was determined. In addition, the topographic relationship between the OCT-measured RNFL thickness and the localized RNFL defect location according to red-free fundus photography (i.e., the red-free RNFL defect) was examined. results. The sensitivity of the Stratus OCT RNFL thickness parameters ranged from 2.0% to 40.8%. The highest sensitivity was yielded using a criterion of > or =1 clock hour that were abnormal at the 5% level, which had a specificity of 85.7%. The OCT-measured RNFL thickness showed excellent topographic agreement with the red-free RNFL defect location. CONCLUSIONS: Although the sensitivity of current Stratus OCT RNFL thickness parameters is low for preperimetric localized RNFL defects, it appears that OCT has the potential to recognize such defects. Further study is needed to develop new analytical methods that will increase OCT sensitivity for identifying preperimetric localized RNFL damage

    Ab initio study of the effect of water adsorption on the carbon nanotube field-effect transistor

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    We perform density-functional calculations to investigate the effect of adsorbed water molecules on carbon nanotubes (CNTs). Noting that the H2 O molecule has much wider energy gap than the CNT, we find that the charge transfer between them is negligible. We discuss that several recent publications, which claimed a substantial electron transfer from the water molecule to the CNT, have been based on incautious interpretations of the Mulliken population analysis. We suggest that the effect of humidity on nanotube devices may be attributed to various indirect effects enhanced by water vapors, rather than the carrier generations by the physisorbed H2 O molecules.open292
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