868 research outputs found

    Candidates for a possible third-generation gravitational wave detector: comparison of ring-Sagnac and sloshing-Sagnac speedmeter interferometers

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    Speedmeters are known to be quantum non-demolition devices and, by potentially providing sensitivity beyond the standard quantum limit, become interesting for third generation gravitational wave detectors. Here we introduce a new configuration, the sloshing-Sagnac interferometer, and compare it to the more established ring-Sagnac interferometer. The sloshing-Sagnac interferometer is designed to provide improved quantum noise limited sensitivity and lower coating thermal noise than standard position meter interferometers employed in current gravitational wave detectors. We compare the quantum noise limited sensitivity of the ring-Sagnac and the sloshing-Sagnac interferometers, in the frequency range, from 5 Hz to 100 Hz, where they provide the greatest potential benefit. We evaluate the improvement in terms of the unweighted noise reduction below the standard quantum limit, and by finding the range up to which binary black hole inspirals may be observed. The sloshing-Sagnac was found to give approximately similar or better sensitivity than the ring-Sagnac in all cases. We also show that by eliminating the requirement for maximally-reflecting cavity end mirrors with correspondingly-thick multi-layer coatings, coating noise can be reduced by a factor of approximately 2.2 compared to conventional interferometers

    Searching for Radio Pulsars in 3EG Sources at Urumqi Observatory

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    Since mid-2005, a pulsar searching system has been operating at 18 cm on the 25-m radio telescope of Urumqi Observatory. Test observations on known pulsars show that the system can perform the intended task. The prospect of using this system to observe 3EG sources and other target searching tasks is discussed.Comment: a training project about MSc thesi

    Instanton size distribution in O(3)

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    We present calculations of the size distribution of instantons in the 2d O(3) non-linear sigma-model, and briefly discuss the effects cooling has upon the configurations and the topological objects. (This preprint is also available via anonymous ftp to suna.amtp.liv.ac.uk in /pub/pss/ as instdist.uue.)Comment: 17 pages, LaTeX, needs cite.sty (appended), with appended uuencoded compressed tarfile of PostScript figures, Liverpool preprint LTH-33

    A "Littlest Higgs" Model with Custodial SU(2) Symmetry

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    In this note, a ``littlest higgs'' model is presented which has an approximate custodial SU(2) symmetry. The model is based on the coset space SO(9)/(SO(5)×SO(4))SO(9)/(SO(5)\times SO(4)). The light pseudo-goldstone bosons of the theory include a {\it single} higgs doublet below a TeV and a set of three SU(2)WSU(2)_W triplets and an electroweak singlet in the TeV range. All of these scalars obtain approximately custodial SU(2) preserving vacuum expectation values. This model addresses a defect in the earlier SO(5)×SU(2)×U(1)SO(5)\times SU(2)\times U(1) moose model, with the only extra complication being an extended top sector. Some of the precision electroweak observables are computed and do not deviate appreciably from Standard Model predictions. In an S-T oblique analysis, the dominant non-Standard Model contributions are the extended top sector and higgs doublet contributions. In conclusion, a wide range of higgs masses is allowed in a large region of parameter space consistent with naturalness, where large higgs masses requires some mild custodial SU(2) violation from the extended top sector.Comment: 22 pages + 8 figures; JHEP style, added references and extra discussion on size of T contributions, as well as some other minor clarifications. Version to appear in JHE

    Tranexamic acid toxicity in human periarticular tissues

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    Objectives: Tranexamic acid (TXA) is an anti-fibrinolytic medication commonly used to reduce perioperative bleeding. Increasingly, topical administration as an intra-articular injection or perioperative wash is being administered during surgery. Adult soft tissues have a poor regenerative capacity and therefore damage to these tissues can be harmful to the patient. This study investigated the effects of TXA on human periarticular tissues and primary cell cultures using clinically relevant concentrations. Methods: Tendon, synovium, and cartilage obtained from routine orthopaedic surgeries were used for ex vivo and in vitro studies using various concentrations of TXA. The in vitro effect of TXA on primary cultured tenocytes, fibroblast-like synoviocytes, and chondrocytes was investigated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) cell viability assays, fluorescent microscopy, and multi-protein apoptotic arrays for cell death. Results: There was a significant (p < 0.01) increase in cell death within all tissue explants treated with 100 mg/ml TXA. MTT assays revealed a significant (p < 0.05) decrease in cell viability in all tissues following treatment with 50 mg/ml or 100 mg/ml of TXA within four hours. There was a significant (p < 0.05) increase in cell apoptosis after one hour of exposure to TXA (100 mg/ml) in all tissues. Conclusion: The current study demonstrates that TXA caused significant periarticular tissue toxicity ex vivo and in vitro at commonly used clinical concentrations

    Characterisation of the diffusion properties of metal foam hybrid flow-fields for fuel cells using optical flow visualisation and x-ray computed tomography

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    The flow distribution behaviour of open-cell metallic foam fuel cell flow-fields are evaluated using ex-situ optical analysis and X-ray computed tomography (X-ray CT). Five different manifold designs are evaluated and flow distribution and pressure drop quantitatively evaluated with reference to applications in polymer exchange membrane fuel cells (PEMFC) and heat exchangers. A ‘hybrid’ foam flow-field is presented consisting of flow channels pressed into the foam to promote flow distribution and reduce pressure drop. Cross- and through-channel pressure drop measurements are conducted, along with X-ray CT analysis. Results using dyed water show that metallic foams provide excellent fluid distribution across the fuel cell flow-field, closely following the theoretical filling rate. The time for dye to cover 80% of the flow-field area was 61% faster with a foam flow-field then with no flow-field present. Pressure drop was seen to reduce with increasing foam inlet area to levels comparable to multi-serpentine flow-fields. The introduction of flow channels in the foam can further reduce pressure drop and provide more even filling of the foam, at the expense of increased residence time

    Kinetic Monte Carlo Simulation of Strained Heteroepitaxial Growth with Intermixing

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    An efficient method for the simulation of strained heteroepitaxial growth with intermixing using kinetic Monte Carlo is presented. The model used is based on a solid-on-solid bond counting formulation in which elastic effects are incorporated using a ball and spring model. While idealized, this model nevertheless captures many aspects of heteroepitaxial growth, including nucleation, surface diffusion, and long range effects due elastic interaction. The algorithm combines a fast evaluation of the elastic displacement field with an efficient implementation of a rejection-reduced kinetic Monte Carlo based on using upper bounds for the rates. The former is achieved by using a multigrid method for global updates of the displacement field and an expanding box method for local updates. The simulations show the importance of intermixing on the growth of a strained film. Further the method is used to simulate the growth of self-assembled stacked quantum dots

    EEHV1A glycoprotein B subunit vaccine elicits humoral and cell-mediated immune responses in mice

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    Asian elephants are an endangered species facing many threats, including severe hemorrhagic disease (HD) caused by the elephant endotheliotropic herpesvirus (EEHV). EEHV-HD is the leading cause of death in captive juvenile Asian elephants in North America and Europe, and also affects elephants in their natural range countries. Significant challenges exist for successful treatment of EEHV-HD, which include timely recognition of disease onset and limited availability of highly effective treatment options. To address this problem, our goal is to prevent lethal disease in young elephants by developing a vaccine that elicits robust and durable humoral and cell-mediated immunity against EEHV. EEHV glycoprotein B (gB) is a major target for cellular and humoral immunity in elephants previously exposed to EEHV. Therefore, we generated a vaccine containing recombinant EEHV1A gB together with a liposome formulated TLR-4 and saponin combination adjuvant (SLA-LSQ). CD-1 mice that received one or two vaccinations with the vaccine elicited significant anti-gB antibody and polyfunctional CD4+ and CD8+ T cell responses, while no adverse effects of vaccination were observed. Overall, our findings demonstrate that an adjuvanted gB protein subunit vaccine stimulates robust humoral and cell-mediated immune responses and supports its potential use in elephants
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