961 research outputs found

    Evaluation of a culture-based pathogen identification kit for bacterial causes of bovine mastitis

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    Accurate identification of mastitis-causing bacteria supports effective management and can be used to implement selective use of antimicrobials for treatment. The objectives of this study were to compare the results from a culture-based mastitis pathogen detection test kit (‘VetoRapid’, Vétoquinol) with standard laboratory culture and to evaluate the potential suitability of the test kit to inform a selective treatment programme. Overall 231 quarter milk samples from five UK dairy farms were collected. The sensitivity and specificity of the test kit for the identification of Escherichia coli, Staphylococcus aureus, coagulase-negative staphylococci, Streptococcus uberis and Enterococcus spp. ranged from 17 per cent to 84 per cent and 92 per cent to 98 per cent, respectively. In total, 23 of 68 clinical samples were assigned as meeting the requirement for antimicrobial treatment (Gram-positive organism cultured) according to standard culture results, with the test kit results having sensitivity and specificity of 91 per cent and 78 per cent, respectively. Several occurrences of misidentification are reported, including S. aureus being misidentified as coagulase-negative staphylococci and vice versa. The test kit provides rapid preliminary identification of five common causes of bovine mastitis under UK field conditions and is likely to be suitable for informing selective treatment of clinical mastitis caused by Gram-positive organisms

    Minimal chordal sense of direction and circulant graphs

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    A sense of direction is an edge labeling on graphs that follows a globally consistent scheme and is known to considerably reduce the complexity of several distributed problems. In this paper, we study a particular instance of sense of direction, called a chordal sense of direction (CSD). In special, we identify the class of k-regular graphs that admit a CSD with exactly k labels (a minimal CSD). We prove that connected graphs in this class are Hamiltonian and that the class is equivalent to that of circulant graphs, presenting an efficient (polynomial-time) way of recognizing it when the graphs' degree k is fixed

    Higgs Signal for h to aa at Hadron Colliders

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    We assess the prospect of observing a neutral Higgs boson at hadron colliders in its decay to two spin-zero states, a, for a Higgs mass of 90-130 GeV, when produced in association with a W or Z boson. Such a decay is allowed in extensions of the MSSM with CP-violating interactions and in the NMSSM, and can dominate Higgs boson final states, thereby evading the LEP constraints on standard Higgs boson production. The light spin-zero state decays primarily via a to bb and tau+tau-, so this signal channel retains features distinct from the main backgrounds. Our study shows that at the Tevatron, there may be potential to observe a few events in the bb tau+tau- or bbbb channels with relatively small background, although this observation would be statistically limited. At the LHC, the background problem is more severe, but with cross sections and integrated luminosities orders of magnitude larger than at the Tevatron, the observation of a Higgs boson in this decay mode would be possible. The channel h to aa to bbbb would provide a large statistical significance, with a signal-to-background ratio on the order of 1:2. In these searches, the main challenge would be to retain the adequate tagging efficiency of b's and tau's in the low p_T region.Comment: Version to be published in JHEP. 20 pages, 5 figure

    CLRM-14. OPEN-LABEL, MULTINATIONAL, MULTICENTER, PHASE 3B/4 STUDY OF TRASTUZUMAB DERUXTECAN (T-DXD) IN PATIENTS WITH OR WITHOUT BASELINE BRAIN METASTASIS (BM) WITH PREVIOUSLY TREATED ADVANCED/METASTATIC HUMAN EPIDERMAL GROWTH FACTOR RECEPTOR 2–POSITIVE BREAST CANCER (HER2+ BC): DESTINY-BREAST12

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    Abstract BACKGROUND Despite treatment advances, up to 50% of patients with advanced HER2+ BC develop BM (Zimmer. Cancer Rep. 2020). Patients with HER2+ BC with BM have a worse prognosis than patients without BM. In DESTINY-Breast01, T-DXd demonstrated efficacy in the overall population and preliminary efficacy in a subgroup with stable BM, with a confirmed objective response rate (ORR) of 61.4% and an extracranial confirmed ORR by independent central review (ICR) of 58.3%, median progression-free survival (PFS) of 19.4 and 18.1 mo, and median duration of response (DOR) of 20.8 and 16.9 mo (Modi. Cancer Res. 2021; Jerusalem. Ann Oncol. 2020). Here we describe a trial evaluating T-DXd in patients with previously treated advanced/metastatic HER2+ BC ±BM. DESIGN DESTINY-Breast12 (NCT04739761) is an open-label, multicenter, international (86 sites in the US, Europe, Australia, and Japan), phase 3b/4 study assessing T-DXd 5.4 mg/kg q3w efficacy and safety in patients with previously treated advanced/metastatic HER2+ BC ±BM that progressed with ≥1 prior anti-HER2–based regimen and received ≤2 lines of therapy in the metastatic setting (excluding patients with prior tucatinib). Patients (n=250/cohort) will be enrolled in cohort 1 (−BM at baseline) or 2 (+BM at baseline). BM must be untreated and not needing immediate local therapy or previously treated and stable or progressing. Primary endpoints are ORR (cohort 1) and PFS (cohort 2) (both by RECIST version 1.1 per ICR). Secondary endpoints are OS, DOR, time to progression, duration of subsequent therapy, PFS2, safety, and changes in symptoms, functioning, and QOL in both cohorts; incidence of new symptomatic CNS metastasis (CNSM) in cohort 1; and ORR and CNS ORR by RECIST 1.1 per ICR, CNS PFS and DOR, and time to new CNSM in cohort 2. This is an encore; the original presentation will be at The European Society for Medical Oncology 2021

    Calcification, Dissolution and Test Properties of Modern Planktonic Foraminifera From the Central Atlantic Ocean

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    The mass of well-preserved calcite in planktonic foraminifera shells provides an indication of the calcification potential of the surface ocean. Here we report the shell weight of 8 different abundant planktonic foraminifera species from a set of core-top sediments along the Mid-Atlantic Ridge. The analyses showed that near the equator, foraminifera shells of equivalent size weigh on average 1/3 less than those from the middle latitudes. The carbonate preservation state of the samples was assessed by high resolution X-ray microcomputed tomographic analyses of Globigerinoides ruber and Globorotalia truncatulinoides specimens. The specimen preservation was deemed good and does not overall explain the observed shell mass variations. However, G. ruber shell weights might be to some extent compromised by residual fine debris internal contamination. Deep dwelling species possess heavier tests than their surface-dwelling counterparts, suggesting that the weight of the foraminifera shells changes as a function of the depth habitat. Ambient seawater carbonate chemistry of declining carbonate ion concentration with depth cannot account for this interspecies difference. The results suggest a depth regulating function for plankton calcification, which is not dictated by water column acidity

    Vacuum local and global electromagnetic self-energies for a point-like and an extended field source

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    We consider the electric and magnetic energy densities (or equivalently field fluctuations) in the space around a point-like field source in its ground state, after having subtracted the spatially uniform zero-point energy terms, and discuss the problem of their singular behavior at the source's position. We show that the assumption of a point-like source leads, for a simple Hamiltonian model of the interaction of the source with the electromagnetic radiation field, to a divergence of the renormalized electric and magnetic energy density at the position of the source. We analyze in detail the mathematical structure of such singularity in terms of a delta function and its derivatives. We also show that an appropriate consideration of these singular terms solves an apparent inconsistency between the total field energy and the space integral of its density. Thus the finite field energy stored in these singular terms gives an important contribution to the self-energy of the source. We then consider the case of an extended source, smeared out over a finite volume and described by an appropriate form factor. We show that in this case all divergences in local quantities such as the electric and the magnetic energy density, as well as any inconsistency between global and space-integrated local self-energies, disappear.Comment: 8 pages. The final publication is available at link.springer.co

    Local and Global Casimir Energies: Divergences, Renormalization, and the Coupling to Gravity

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    From the beginning of the subject, calculations of quantum vacuum energies or Casimir energies have been plagued with two types of divergences: The total energy, which may be thought of as some sort of regularization of the zero-point energy, 12ω\sum\frac12\hbar\omega, seems manifestly divergent. And local energy densities, obtained from the vacuum expectation value of the energy-momentum tensor, T00\langle T_{00}\rangle, typically diverge near boundaries. The energy of interaction between distinct rigid bodies of whatever type is finite, corresponding to observable forces and torques between the bodies, which can be unambiguously calculated. The self-energy of a body is less well-defined, and suffers divergences which may or may not be removable. Some examples where a unique total self-stress may be evaluated include the perfectly conducting spherical shell first considered by Boyer, a perfectly conducting cylindrical shell, and dilute dielectric balls and cylinders. In these cases the finite part is unique, yet there are divergent contributions which may be subsumed in some sort of renormalization of physical parameters. The divergences that occur in the local energy-momentum tensor near surfaces are distinct from the divergences in the total energy, which are often associated with energy located exactly on the surfaces. However, the local energy-momentum tensor couples to gravity, so what is the significance of infinite quantities here? For the classic situation of parallel plates there are indications that the divergences in the local energy density are consistent with divergences in Einstein's equations; correspondingly, it has been shown that divergences in the total Casimir energy serve to precisely renormalize the masses of the plates, in accordance with the equivalence principle.Comment: 53 pages, 1 figure, invited review paper to Lecture Notes in Physics volume in Casimir physics edited by Diego Dalvit, Peter Milonni, David Roberts, and Felipe da Ros

    Condensate fluctuations in finite Bose-Einstein condensates at finite temperature

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    A Langevin equation for the complex amplitude of a single-mode Bose-Einstein condensate is derived. The equation is first formulated phenomenologically, defining three transport parameters. It is then also derived microscopically. Expressions for the transport parameters in the form of Green-Kubo formulas are thereby derived and evaluated for simple trap geometries, a cubic box with cyclic boundary conditions and an isotropic parabolic trap. The number fluctuations in the condensate, their correlation time, and the temperature-dependent collapse-time of the order parameter as well as its phase-diffusion coefficient are calculated.Comment: 29 pages, Revtex, to appear in Phys.Rev.
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