498 research outputs found

    Two-Point Functions and S-Parameter in QCD-like Theories

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    We calculated the vector, axial-vector, scalar and pseudo-scalar two-point functions up to two-loop level in the low-energy effective field theory for three different QCD-like theories. In addition we also calculated the pseudo-scalar decay constant GMG_M. The QCD-like theories we used are those with fermions in a complex, real or pseudo-real representation with in general n flavours. These case correspond to global symmetry breaking pattern of SU(n)L×SU(n)R→SU(n)VSU(n)_L\times SU(n)_R\to SU(n)_V, SU(2n)→SO(2n)SU(2n)\to SO(2n) or SU(2n)→Sp(2n)SU(2n)\to Sp(2n). We also estimated the S parameter for those different theories.Comment: 29 page

    Reducing Constraints in a Higher Dimensional Extension of the Randall and Sundrum Model

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    In order to investigate the phenomenological implications of warped spaces in more than five dimensions, we consider a 4+1+δ4+1+\delta dimensional extension to the Randall and Sundrum model in which the space is warped with respect to a single direction by the presence of an anisotropic bulk cosmological constant. The Einstein equations are solved, giving rise to a range of possible spaces in which the δ\delta additional spaces are warped. Here we consider models in which the gauge fields are free to propagate into such spaces. After carrying out the Kaluza Klein (KK) decomposition of such fields it is found that the KK mass spectrum changes significantly depending on how the δ\delta additional dimensions are warped. We proceed to compute the lower bound on the KK mass scale from electroweak observables for models with a bulk SU(2)×U(1)SU(2)\times U(1) gauge symmetry and models with a bulk SU(2)R×SU(2)L×U(1)SU(2)_R\times SU(2)_L\times U(1) gauge symmetry. It is found that in both cases the most favourable bounds are approximately MKK≳2M_{KK}\gtrsim 2 TeV, corresponding to a mass of the first gauge boson excitation of about 4-6 TeV. Hence additional warped dimensions offer a new way of reducing the constraints on the KK scale.Comment: 27 pages, 15 figures, v3: Additional comments in sections 1, 2 and 4. New appendix added. Five additional figures. References adde

    Meson-meson Scattering in QCD-like Theories

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    We discuss meson-meson scattering at next-to-next-to-leading order in the chiral expansion for QCD-like theories with general nn degenerate flavours for the cases with a complex, real and pseudo-real representation. I.e. with global symmetry and breaking pattern SU(n)L×SU(n)R→SU(n)VSU(n)_L\times SU(n)_R\to SU(n)_V, SU(2n)→SO(2n)SU(2n)\to SO(2n) and SU(2n)→Sp(2n)SU(2n)\to Sp(2n). We obtain fully analytical expressions for all these cases. We discuss the general structure of the amplitude and the structure of the possible intermediate channels for all three cases. We derive the expressions for the lowest partial wave scattering length in each channel and present some representative numerical results. We also show various relations between the different cases in the limit of large nn.Comment: 61 page

    EGFR Inhibition in Glioma Cells Modulates Rho Signaling to Inhibit Cell Motility and Invasion and Cooperates with Temozolomide to Reduce Cell Growth

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    Enforced EGFR activation upon gene amplification and/or mutation is a common hallmark of malignant glioma. Small molecule EGFR tyrosine kinase inhibitors, such as erlotinib (Tarceva), have shown some activity in a subset of glioma patients in recent trials, although the reported data on the cellular basis of glioma cell responsiveness to these compounds have been contradictory. Here we have used a panel of human glioma cell lines, including cells with amplified or mutant EGFR, to further characterize the cellular effects of EGFR inhibition with erlotinib. Dose-response and cellular growth assays indicate that erlotinib reduces cell proliferation in all tested cell lines without inducing cytotoxic effects. Flow cytometric analyses confirm that EGFR inhibition does not induce apoptosis in glioma cells, leading to cell cycle arrest in G1. Interestingly, erlotinib also prevents spontaneous multicellular tumour spheroid growth in U87MG cells and cooperates with sub-optimal doses of temozolomide (TMZ) to reduce multicellular tumour spheroid growth. This cooperation appears to be schedule-dependent, since pre-treatment with erlotinib protects against TMZ-induced cytotoxicity whereas concomitant treatment results in a cooperative effect. Cell cycle arrest in erlotinib-treated cells is associated with an inhibition of ERK and Akt signaling, resulting in cyclin D1 downregulation, an increase in p27kip1 levels and pRB hypophosphorylation. Interestingly, EGFR inhibition also perturbs Rho GTPase signaling and cellular morphology, leading to Rho/ROCK-dependent formation of actin stress fibres and the inhibition of glioma cell motility and invasion

    Reaction rates and transport in neutron stars

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    Understanding signals from neutron stars requires knowledge about the transport inside the star. We review the transport properties and the underlying reaction rates of dense hadronic and quark matter in the crust and the core of neutron stars and point out open problems and future directions.Comment: 74 pages; commissioned for the book "Physics and Astrophysics of Neutron Stars", NewCompStar COST Action MP1304; version 3: minor changes, references updated, overview graphic added in the introduction, improvements in Sec IV.A.

    Screening for psychological distress in patients with lung cancer: results of a clinical audit evaluating the use of the patient Distress Thermometer

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    Patients with lung cancer frequently suffer psychological distress and guidelines in the United Kingdom recommend screening of all cancer patients for this problem. The audit investigated use of the Distress Thermometer in terms of staff adherence to locally developed guidelines, patient willingness to use the tool, its impact on referral rates to clinical psychology services and concordance between the tool and the clinical assessment. Use of the Distress Thermometer was audited over a 3-month period in one lung cancer outpatient clinic. Referrals to clinical psychology services in response to clearly delineated referral indicators were assessed. Patient-reported outcomes were compared with practitioner assessment of need during clinical consultations to see whether the tool was measuring distress effectively. Thirty three of 34 patients used the Distress Thermometer during the audit period. Ten reported distress levels above 4 in the emotional or family problems domains. On ten occasions, the clinical interview identified problems not elicited by the Distress Thermometer. Guidelines were adhered to by staff, and patients were offered information about local support services and referral to clinical psychology services where indicated. Whilst all patients were happy to receive written information about further sources of support, none wanted to be referred to psychological services at that time. The Distress Thermometer is acceptable to patients with lung cancer in outpatient settings but it did not increase referrals for psychological support. Staff found it to be a useful tool in opening up communication about patient issues although it should not replace a comprehensive clinical interview

    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

    Fresh-blood-free diet for rearing malaria mosquito vectors

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    Mosquito breeding depends on the supply of fresh vertebrate blood, a major bottleneck for large-scale production of Anopheles spp. Feeding alternatives to fresh blood are thus a priority for research, outdoor large-cage trials and control interventions. Several artificial meal compositions were tested and Anopheles oogenesis, egg laying and development into the next generation of adult mosquitoes were followed. We identified blood-substitute-diets that supported ovarian development, egg maturation and fertility as well as, low progeny larval mortality, and normal development of offspring into adult mosquitoes. The formulated diet is an effective artificial meal, free of fresh blood that mimics a vertebrate blood meal and represents an important advance for the sustainability of Anopheles mosquito rearing in captivity.Agência financiadora / Número do subsídio Bill and Melinda Gates Foundation OPP1138841 Fundacao para a Ciencia e Tecnologia GHTM - UID/Multi/04413/201 CCMAR - UID/Multi/04326/2013 UID/Multi/04326/2013 RF SFRH/BPD/89811/2012 FAPEAM, Brazil 19716.UNI472.2459.20022014info:eu-repo/semantics/publishedVersio

    Direct imaging of the coexistence of ferromagnetism and superconductivity at the LaAlO3/SrTiO3 interface

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    LaAlO3 and SrTiO3 are insulating, nonmagnetic oxides, yet the interface between them exhibits a two-dimensional electron system with high electron mobility,1 superconductivity at low temperatures,2-6 and electric-field-tuned metal-insulator and superconductorinsulator phase transitions.3,6-8 Bulk magnetization and magnetoresistance measurements also suggest some form of magnetism depending on preparation conditions5,9-11 and suggest a tendency towards nanoscale electronic phase separation.10 Here we use local imaging of the magnetization and magnetic susceptibility to directly observe a landscape of ferromagnetism, paramagnetism, and superconductivity. We find submicron patches of ferromagnetism in a uniform background of paramagnetism, with a nonuniform, weak diamagnetic superconducting susceptibility at low temperature. These results demonstrate the existence of nanoscale phase separation as suggested by theoretical predictions based on nearly degenerate interface sub-bands associated with the Ti orbitals.12,13 The magnitude and temperature dependence of the paramagnetic response suggests that the vast majority of the electrons at the interface are localized, and do not contribute to transport measurements.3,6,7 In addition to the implications for magnetism, the existence of a 2D superconductor at an interface with highly broken inversion symmetry and a ferromagnetic landscape in the background suggests the potential for exotic superconducting phenomena.Comment: Edited version to appear in Nature Physic

    Physics of Neutron Star Crusts

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    The physics of neutron star crusts is vast, involving many different research fields, from nuclear and condensed matter physics to general relativity. This review summarizes the progress, which has been achieved over the last few years, in modeling neutron star crusts, both at the microscopic and macroscopic levels. The confrontation of these theoretical models with observations is also briefly discussed.Comment: 182 pages, published version available at <http://www.livingreviews.org/lrr-2008-10
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