95 research outputs found

    The Evolution of Compact Binary Star Systems

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    We review the formation and evolution of compact binary stars consisting of white dwarfs (WDs), neutron stars (NSs), and black holes (BHs). Binary NSs and BHs are thought to be the primary astrophysical sources of gravitational waves (GWs) within the frequency band of ground-based detectors, while compact binaries of WDs are important sources of GWs at lower frequencies to be covered by space interferometers (LISA). Major uncertainties in the current understanding of properties of NSs and BHs most relevant to the GW studies are discussed, including the treatment of the natal kicks which compact stellar remnants acquire during the core collapse of massive stars and the common envelope phase of binary evolution. We discuss the coalescence rates of binary NSs and BHs and prospects for their detections, the formation and evolution of binary WDs and their observational manifestations. Special attention is given to AM CVn-stars -- compact binaries in which the Roche lobe is filled by another WD or a low-mass partially degenerate helium-star, as these stars are thought to be the best LISA verification binary GW sources.Comment: 105 pages, 18 figure

    The Proteomic Code: a molecular recognition code for proteins

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    <p>Abstract</p> <p>Background</p> <p>The Proteomic Code is a set of rules by which information in genetic material is transferred into the physico-chemical properties of amino acids. It determines how individual amino acids interact with each other during folding and in specific protein-protein interactions. The Proteomic Code is part of the redundant Genetic Code.</p> <p>Review</p> <p>The 25-year-old history of this concept is reviewed from the first independent suggestions by Biro and Mekler, through the works of Blalock, Root-Bernstein, Siemion, Miller and others, followed by the discovery of a Common Periodic Table of Codons and Nucleic Acids in 2003 and culminating in the recent conceptualization of partial complementary coding of interacting amino acids as well as the theory of the nucleic acid-assisted protein folding.</p> <p>Methods and conclusions</p> <p>A novel cloning method for the design and production of specific, high-affinity-reacting proteins (SHARP) is presented. This method is based on the concept of proteomic codes and is suitable for large-scale, industrial production of specifically interacting peptides.</p

    The LUX-ZEPLIN (LZ) Experiment

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    We describe the design and assembly of the LUX-ZEPLIN experiment, a direct detection search for cosmic WIMP dark matter particles. The centerpiece of the experiment is a large liquid xenon time projection chamber sensitive to low energy nuclear recoils. Rejection of backgrounds is enhanced by a Xe skin veto detector and by a liquid scintillator Outer Detector loaded with gadolinium for efficient neutron capture and tagging. LZ is located in the Davis Cavern at the 4850' level of the Sanford Underground Research Facility in Lead, South Dakota, USA. We describe the major subsystems of the experiment and its key design features and requirements

    A spontaneous ad hoc network to share www access

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    In this paper, we propose a secure spontaneous ad-hoc network, based on direct peer-to-peer interaction, to grant a quick, easy, and secure access to the users to surf the Web. The paper shows the description of our proposal, the procedure of the nodes involved in the system, the security algorithms implemented, and the designed messages. We have taken into account the security and its performance. Although some people have defined and described the main features of spontaneous ad-hoc networks, nobody has published any design and simulation until today. Spontaneous networking will enable a more natural form of wireless computing when people physically meet in the real world. We also validate the success of our proposal through several simulations and comparisons with a regular architecture, taking into account the optimization of the resources of the devices. Finally, we compare our proposal with other caching techniques published in the related literature. The proposal has been developed with the main objective of improving the communication and integration between different study centers of low-resource communities. That is, it lets communicate spontaneous networks, which are working collaboratively and which have been created on different physical places.Authors want to give thanks to the anonymous reviewers for their valuable suggestions, useful comments, and proofreading of this paper. This work was partially supported by the Ministerio de Educacion y Ciencia, Spain, under Grant no. TIN2008-06441-C02-01, and by the "Ayudas complementarias para proyectos de I+D para grupos de calidad de la Generalitat Valenciana" (ACOMP/2010/005).Lacuesta Gilaberte, R.; Lloret, J.; García Pineda, M.; Peñalver Herrero, ML. (2010). A spontaneous ad hoc network to share www access. 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Proceedings of the 38th Annual Hawaii International Conference on System Sciences (HICSS '05), January 2005, Big Island, Hawaii, USAGokhale S, Dasgupta P: Distributed authentication for peer-to-peer networks. Proceedings of the Symposium on Applications and the Internet Workshops, January 2003 347-353.Capkun S, Buttyán L, Hubaux J-P: Self-organized public-key management for mobile ad hoc networks. IEEE Transactions on Mobile Computing 2003, 2(1):52-64. 10.1109/TMC.2003.1195151Stajano F, Anderson R: The resurrecting duckling security issues for ad-hoc wireless networks. In Proceedings of the 7th International Workshop on Security Protocols, 1999, Berlin, Germany, Lecture Notes in Computer Science. Volume 1796. Springer; 172-194.Balfanz D, Smetters DK, Stewart P, Wong HC: Talking to strangers: authentication in ad-hoc wireless networks. Proceedings of the International Symposium on Network and Distributed Systems Security (NDSS '02), February 2002, San Diego, Calif, USABarbara D, Imielinski T: Sleepers and workaholics: caching strategies in mobile environments. Proceedings of the ACM SIGMOD International Conference on Management of Data, May 1994 1-12.Cao G: A scalable low-latency cache invalidation strategy for mobile environments. IEEE Transactions on Knowledge and Data Engineering 2003, 15(5):1251-1265. 10.1109/TKDE.2003.1232276Hu Q, Lee D: Cache algorithms based on adaptive invalidation reports for mobile environments. Cluster Computing 1998, 1(1):39-50. 10.1023/A:1019012927328Jing J, Elmagarmid A, Helal A, Alonso R: Bit-sequences: an adaptive cache invalidation method in mobile client/server environments. Mobile Networks and Applications 1997, 2(2):115-127. 10.1023/A:1013616213333Kahol A, Khurana S, Gupta S, Srimani P: An efficient cache management scheme for mobile environment. 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IEEE Transactions on Mobile Computing 2005, 4(1):68-83.Wessels D, Claffy K: Internet cache protocol (IC) v.2. http://www.ietf.org/rfc/rfc2186.txtFan L, Cao P, Almeida J, Broder AZ: Summary cache: a scalable wide-area web cache sharing protocol. IEEE/ACM Transactions on Networking 2000, 8(3):281-293. 10.1109/90.851975Dykes SG, Robbins KA: A viability analysis of cooperative proxy caching. Proceedings of the 20th Annual Joint Conference of the IEEE Computer and Communications Societies (INFOCOM '01), April 2001, Anchorage, Alaska, USA 3: 1205-1214.Wessels D, Claffy K: RFC 2186: Internet cache protocol (ICP), version 2. The Internet Engineering Taskforce, September 1997Wessels D, Claffy K: RFC 2187: application of internet cache protocol (ICP), version 2. The Internet Engineering Taskforce, September 1997Ren Q, Dunhan MH: Using semantic caching to manage location dependent data in mobile computing. 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Proceedings of the 18th IEEE Symposium on Reliable Distributed Systems (SRDS '99), October 1999, Lausanne, Switzerland 4-13.Corson MS, Macker JP, Cirincione GH: Internet-based mobile ad hoc networking. IEEE Internet Computing 1999, 3(4):63-70. 10.1109/4236.780962Lim S, Lee W-C, Cao G, Das CR: A novel caching scheme for improving internet-based mobile ad hoc networks performance. Ad Hoc Networks 2006, 4(2):225-239. 10.1016/j.adhoc.2004.04.013Opnet Modeler http://www.opnet.com/solutions/network_rd/modeler_wireless.htmlLacuesta R, Lloret J, Garcia M, Peñalver L: Two secure and energy-saving spontaneous ad-hoc protocol for wireless mesh client networks. Journal of Network and Computer Applications. In pres

    Chemical-genetic disruption of clathrin function spares adaptor complex 3-dependent endosome vesicle biogenesis

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    A role for clathrin in AP-3–dependent vesicle biogenesis has been inferred from biochemical interactions and colocalization between this adaptor and clathrin. The functionality of these molecular associations, however, is controversial. We comprehensively explore the role of clathrin in AP-3–dependent vesicle budding, using rapid chemical-genetic perturbation of clathrin function with a clathrin light chain–FKBP chimera oligomerizable by the drug AP20187. We find that AP-3 interacts and colocalizes with endogenous and recombinant FKBP chimeric clathrin polypeptides in PC12-cell endosomes. AP-3 displays, however, a divergent behavior from AP-1, AP-2, and clathrin chains. AP-3 cofractionates with clathrin-coated vesicle fractions isolated from PC12 cells even after clathrin function is acutely inhibited by AP20187. We predicted that AP20187 would inhibit AP-3 vesicle formation from endosomes after a brefeldin A block. AP-3 vesicle formation continued, however, after brefeldin A wash-out despite impairment of clathrin function by AP20187. These findings indicate that AP-3–clathrin association is dispensable for endosomal AP-3 vesicle budding and suggest that endosomal AP-3–clathrin interactions differ from those by which AP-1 and AP-2 adaptors productively engage clathrin in vesicle biogenesis

    The LUX-ZEPLIN (LZ) radioactivity and cleanliness control programs

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    LUX-ZEPLIN (LZ) is a second-generation direct dark matter experiment with spin-independent WIMP-nucleon scattering sensitivity above 1.4×10−48cm2 for a WIMP mass of 40GeV/c2 and a 1000days exposure. LZ achieves this sensitivity through a combination of a large 5.6t fiducial volume, active inner and outer veto systems, and radio-pure construction using materials with inherently low radioactivity content. The LZ collaboration performed an extensive radioassay campaign over a period of six years to inform material selection for construction and provide an input to the experimental background model against which any possible signal excess may be evaluated. The campaign and its results are described in this paper. We present assays of dust and radon daughters depositing on the surface of components as well as cleanliness controls necessary to maintain background expectations through detector construction and assembly. Finally, examples from the campaign to highlight fixed contaminant radioassays for the LZ photomultiplier tubes, quality control and quality assurance procedures through fabrication, radon emanation measurements of major sub-systems, and bespoke detector systems to assay scintillator are presented

    Effects of antiplatelet therapy after stroke due to intracerebral haemorrhage (RESTART): a randomised, open-label trial

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    BACKGROUND: Antiplatelet therapy reduces the risk of major vascular events for people with occlusive vascular disease, although it might increase the risk of intracranial haemorrhage. Patients surviving the commonest subtype of intracranial haemorrhage, intracerebral haemorrhage, are at risk of both haemorrhagic and occlusive vascular events, but whether antiplatelet therapy can be used safely is unclear. We aimed to estimate the relative and absolute effects of antiplatelet therapy on recurrent intracerebral haemorrhage and whether this risk might exceed any reduction of occlusive vascular events. METHODS: The REstart or STop Antithrombotics Randomised Trial (RESTART) was a prospective, randomised, open-label, blinded endpoint, parallel-group trial at 122 hospitals in the UK. We recruited adults (≥18 years) who were taking antithrombotic (antiplatelet or anticoagulant) therapy for the prevention of occlusive vascular disease when they developed intracerebral haemorrhage, discontinued antithrombotic therapy, and survived for 24 h. Computerised randomisation incorporating minimisation allocated participants (1:1) to start or avoid antiplatelet therapy. We followed participants for the primary outcome (recurrent symptomatic intracerebral haemorrhage) for up to 5 years. We analysed data from all randomised participants using Cox proportional hazards regression, adjusted for minimisation covariates. This trial is registered with ISRCTN (number ISRCTN71907627). FINDINGS: Between May 22, 2013, and May 31, 2018, 537 participants were recruited a median of 76 days (IQR 29-146) after intracerebral haemorrhage onset: 268 were assigned to start and 269 (one withdrew) to avoid antiplatelet therapy. Participants were followed for a median of 2·0 years (IQR [1·0- 3·0]; completeness 99·3%). 12 (4%) of 268 participants allocated to antiplatelet therapy had recurrence of intracerebral haemorrhage compared with 23 (9%) of 268 participants allocated to avoid antiplatelet therapy (adjusted hazard ratio 0·51 [95% CI 0·25-1·03]; p=0·060). 18 (7%) participants allocated to antiplatelet therapy experienced major haemorrhagic events compared with 25 (9%) participants allocated to avoid antiplatelet therapy (0·71 [0·39-1·30]; p=0·27), and 39 [15%] participants allocated to antiplatelet therapy had major occlusive vascular events compared with 38 [14%] allocated to avoid antiplatelet therapy (1·02 [0·65-1·60]; p=0·92). INTERPRETATION: These results exclude all but a very modest increase in the risk of recurrent intracerebral haemorrhage with antiplatelet therapy for patients on antithrombotic therapy for the prevention of occlusive vascular disease when they developed intracerebral haemorrhage. The risk of recurrent intracerebral haemorrhage is probably too small to exceed the established benefits of antiplatelet therapy for secondary prevention. FUNDING: British Heart Foundation
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