The role of lipid rafts in T cell antigen receptor (TCR) signaling was investigated using fluorescence microscopy. Lipid rafts labeled with cholera toxin B subunit (CT-B) and cross-linked into patches displayed characteristics of rafts isolated biochemically, including detergent resistance and colocalization with raft-associated proteins. LCK, LAT, and the TCR all colocalized with lipid patches, although TCR association was sensitive to nonionic detergent. Aggregation of the TCR by anti-CD3 mAb cross-linking also caused coaggregation of raft-associated proteins. However, the protein tyrosine phosphatase CD45 did not colocalize to either CT-B or CD3 patches. Cross-linking of either CD3 or CT-B strongly induced tyrosine phosphorylation and recruitment of a ZAP-70(SH2)2–green fluorescent protein (GFP) fusion protein to the lipid patches. Also, CT-B patching induced signaling events analagous to TCR stimulation, with the same dependence on expression of key TCR signaling molecules. Targeting of LCK to rafts was necessary for these events, as a nonraft- associated transmembrane LCK chimera, which did not colocalize with TCR patches, could not reconstitute CT-B–induced signaling. Thus, our results indicate a mechanism whereby TCR engagement promotes aggregation of lipid rafts, which facilitates colocalization of LCK, LAT, and the TCR whilst excluding CD45, thereby triggering protein tyrosine phosphorylation.
We present the first catalog of active galactic nuclei (AGNs) detected by the Large Area Telescope (LAT), corresponding to 11 months of data collected in scientific operation mode. The First LAT AGN Catalog (1LAC) includes 671 γ-ray sources located at high Galactic latitudes (|b|>10°) that are detected with a test statistic greater than 25 and associated statistically with AGNs. Some LAT sources are associated with multiple AGNs, and consequently, the catalog includes 709 AGNs, comprising 300 BL Lacertae objects, 296 flat-spectrum radio quasars, 41 AGNs of other types, and 72 AGNs of unknown type. We also classify the blazars based on their spectral energy distributions as archival radio, optical, and X-ray data permit. In addition to the formal 1LAC sample, we provide AGN associations for 51 low-latitude LAT sources and AGN “affiliations” (unquantified counterpart candidates) for 104 high-latitude LAT sources without AGN associations. The overlap of the 1LAC with existing γ-ray AGN catalogs (LBAS, EGRET, AGILE, Swift, INTEGRAL, TeVCat) is briefly discussed. Various properties—such as γ-ray fluxes and photon power-law spectral indices, redshifts, γ-ray luminosities, variability, and archival radio luminosities—and their correlations are presented and discussed for the different blazar classes. We compare the 1LAC results with predictions regarding the γ-ray AGN populations, and we comment on the power of the sample to address the question of the blazar sequence.
Magnesium alloy is considered as one of the ideal cardiovascular stent materials owing to its good mechanical properties and biodegradability. However, the in vivo rapid degradation rate and the insufficient biocompatibility restrict its clinical applications. In this study, the magnesium alloy (AZ31B) was modified by combining the surface chemical treatment and in-situ self-assembly of 16-phosphonyl-hexadecanoic acid, followed by the immobilization of chitosan-functionalized graphene oxide (GOCS). Heparin (Hep) and GOCS were alternatively immobilized on the GOCS-modified surface through layer by layer (LBL) to construct the GOCS/Hep bioactive multilayer coating, and the corrosion resistance and biocompatibility were extensively explored. The results showed that the GOCS/Hep bioactive multilayer coating can endow magnesium alloys with an excellent in vitro corrosion resistance. The GOCS/Hep multilayer coating can significantly reduce the hemolysis rate and the platelet adhesion and activation, resulting in an excellent blood compatibility. In addition, the multilayer coating can not only enhance the adhesion and proliferation of the endothelial cells, but also promote the vascular endothelial growth factor (VEGF) and nitric oxide (NO) expression of the attached endothelial cells on the surfaces. Therefore, the method of the present study can be used to simultaneously control the corrosion resistance and improve the biocompatibility of the magnesium alloys, which is expected to promote the application of magnesium alloys in biomaterials or medical devices, especially cardiovascular stent.
This catalog summarizes 117 high-confidence ≥ 0.1 GeV gamma-ray pulsar detections using three years of data acquired by the Large Area Telescope (LAT) on the Fermi satellite. Half are neutron stars discovered using LAT data, Japan Istituto Nazionale di Fisica Nucleare, Sezione di Roma “Tor Vergata”, I-00133 Roma, Italy 1-4-12 Kojirakawa-machi, Yamagata-shi, 990-8560 Japan Institute of Space and Astronautical Science, JAXA, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210, Japan Department of Physics and Astronomy, University of Denver, Denver, CO 80208, USA Max-Planck-Institut für Physik, D-80805 München, Germany Albert-Einstein-Institut, Max-Planck-Institut für Gravitationsphysik, D-30167 Hannover, Germany Leibniz Universität Hannover, D-30167 Hannover, Germany National Radio Astronomy Observatory (NRAO), Charlottesville, VA 22903, USA Department of Physics, Washington University, St. Louis, MO 63130, USA Space Sciences Division, NASA Ames Research Center, Moffett Field, CA 94035-1000, USA NYCB Real-Time Computing Inc., Lattingtown, NY 11560-1025, USA email: smith@cenbg.in2p3.fr Max-Planck Institut für extraterrestrische Physik, 85748 Garching, Germany Department of Chemistry and Physics, Purdue University Calumet, Hammond, IN 46323-2094, USA Department of Physics, Willamette University, Salem, OR 97031, USA Institut für Theoretische Physik and Astrophysik, Universität Würzburg, D-97074 Würzburg, Germany Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain NASA Postdoctoral Program Fellow, USA 3-34-1 Nishi-Ikebukuro,Toshima-ku, , Tokyo Japan 171-8501 Centre for Space Research, North-West University, Potchefstroom Campus, Private Bag X6001, 2520 Potchefstroom, South Africa Consorzio Interuniversitario per la Fisica Spaziale (CIFS), I-10133 Torino, Italy Dipartimento di Fisica, Università di Roma “Tor Vergata”, I-00133 Roma, Italy Xinjiang Astronomical Observatory, CAS, Urumqi, 830011, China Praxis Inc., Alexandria, VA 22303, resident at Naval Research Laboratory, Washington, DC 20375, USA
T. F. L. C. M. Ajello, M. Axelsson, R. Bagagli
et al.
The Large Area Telescope (LAT), the primary instrument for the Fermi Gamma-ray Space Telescope (Fermi) mission, is an imaging, wide field-of-view, high-energy gamma-ray telescope, covering the energy range from 30 MeV to more than 300 GeV. We describe the performance of the instrument at the 10 yr milestone. LAT performance remains well within the specifications defined during the planning phase, validating the design choices and supporting the compelling case to extend the duration of the Fermi mission. The details provided here will be useful when designing the next generation of high-energy gamma-ray observatories.
Abstract This paper proposes a quantitative human reliability analysis (HRA) model based on fuzzy logic theory, Bayesian network, and cognitive reliability & error analysis method (CREAM) for the tanker shipping industry. The common performance conditions (CPCs) in conventional CREAM approach are custom-modified to better capture the salient aspects of the situations and conditions for on-board tanker work. Fuzzy logic technique using triangle and trapezoidal membership functions is applied to model the uncertainty and ambiguity of the CPCs as well the control modes in CREAM. A Bayesian network reasoning model using the membership of CPCs as inputs is developed which determines the probability distribution of the control modes. Human error probability (HEP) is obtained from memberships of the control modes and the results of Bayesian network reasoning. A case study in tanker shipping industry with 18 crew members is provided, and the results show that the evaluation of HEP according to the proposed HRA model is very promising and the HRA model is consistent with the original CREAM approach. The sensitivity of the model is also checked against the inputs of the crew members. It is concluded that the enhanced HRA model is able to provide reliable human performance failure results.
Abstract Exploring renewable bio-based polymer materials with intrinsic flame retardancy and high mechanical strength will greatly increase the potential to meet fire safety and practicability requirements. In this study, a hexa-substituted cyclophosphazene monomer (HEP) is synthesized from abundant and renewable eugenol and then copolymerized with multi-thiol monomers to establish HEP-SH polymer networks by thiol-ene photopolymerization. Four HEP-SH polymer networks (HEP-TEGDT, HEP-TTMP, HEP-PETMP, HEP-TEMPIC) were prepared by varying the number of thiol groups or the backbone of thiol monomers. Among these polymer networks, HEP-PETMP and HEP-TEMPIC networks exhibit excellent flame retardancy (LOI > 27 vol.%, achieved UL 94 V-0 rating). The combustion parameters and flame retardant mechanism are further studied by cone calorimetry and combined scanning electron microscopy/energy-dispersive spectroscopy (SEM-EDS), which confirm the intumescent flame retardancy of HEP-SH networks is simultaneously affected by the contents of phosphorus and nitrogen element, as well as the structural features of the polymer network. In addition, the HEP-TEMPIC and HEP-PETMP networks also exhibit high mechanical strength and transparency. These eugenol-based thiol-ene polymer networks open a new pathway to develop sustainable high-performance flame retardant bio-based polymer materials for practical application.
Abstract The fundamental issue in reference to human reliability analysis (HRA) in a nuclear power plant is the lack of empirical data for human error probability (HEP) estimation, and lower level information of human performance that can be used to estimate HEPs. In an effort to resolve this issue, the Korea Atomic Energy Research Institute (KAERI) developed a framework, known as human reliability data extraction (HuREX), for data collection and analyses from a simulator to generate HRA data, such as HEPs, or for correlations between performance shaping factors (PSFs) and the associated HEPs. HuREX provides guidance on the identification of unsafe act (UA) and the processing of collected data. In addition, it allows us to analyze collected data based on the associated forms and taxonomy on generic task types and error modes. An application study was carried out using two sets of full-scope training simulator records to confirm the suitability of HuREX and to generate the HEPs of generic task types with respect to reference plants. As a result, 37 HEPs were successfully quantified for 21 generic task types.
In this study, hot water, 0.9% NaCl, citric acid, and 1.25 M NaOH/0.05% NaBH4 were separately used for the extraction of water-soluble H. erinaceus polysaccharides (HEPs; HEP-W, HEP-S, HEP-C, and HEP-A) from the fruit body of Hericium erinaceus. The physicochemical properties and biological activities were then investigated and compared. Results showed that the extraction solvents exhibited significant effects on the extraction yields, molecular weights, monosaccharide compositions, preliminary structural characteristics, microstructures of HEPs and on their contents, such as neutral sugar, uronic acid, protein, and β-(1 → 3)-glucan. In vitro antioxidant activity assays indicated that HEP-C extracted with citric acid solution showed stronger scavenging abilities on hydroxyl and DPPH radicals and antioxidant capacities than HEP-W and HEP-S. Moreover, HEP-C exhibited the strongest inhibitory effects on α-glycosidase and α-amylase activities. Therefore, HEP-C extracted with citric acid can be developed as a potential bioactive ingredient for applications in food, medicine, and cosmetics industries.