496 research outputs found

    Hawking radiation in different coordinate settings: Complex paths approach

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    We apply the technique of complex paths to obtain Hawking radiation in different coordinate representations of the Schwarzschild space-time. The coordinate representations we consider do not possess a singularity at the horizon unlike the standard Schwarzschild coordinate. However, the event horizon manifests itself as a singularity in the expression for the semiclassical action. This singularity is regularized by using the method of complex paths and we find that Hawking radiation is recovered in these coordinates indicating the covariance of Hawking radiation as far as these coordinates are concerned.Comment: 18 pages, 2 figures, Uses IOP style file; final version; accepted in Class. Quant. Gra

    Ion Beam Tracking using Ultrasound Motion Detection

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    Measurement of the Transverse Beam Spin Asymmetry in Elastic Electron Proton Scattering and the Inelastic Contribution to the Imaginary Part of the Two-Photon Exchange Amplitude

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    We report on a measurement of the asymmetry in the scattering of transversely polarized electrons off unpolarized protons, A⊄_\perp, at two Q2^2 values of \qsquaredaveragedlow (GeV/c)2^2 and \qsquaredaveragedhighII (GeV/c)2^2 and a scattering angle of 30∘<Ξe<40∘30^\circ < \theta_e < 40^\circ. The measured transverse asymmetries are A⊄_{\perp}(Q2^2 = \qsquaredaveragedlow (GeV/c)2^2) = (\experimentalasymmetry alulowcorr ±\pm \statisticalerrorlowstat_{\rm stat} ±\pm \combinedsyspolerrorlowalucorsys_{\rm sys}) ×\times 10−6^{-6} and A⊄_{\perp}(Q2^2 = \qsquaredaveragedhighII (GeV/c)2^2) = (\experimentalasymme tryaluhighcorr ±\pm \statisticalerrorhighstat_{\rm stat} ±\pm \combinedsyspolerrorhighalucorsys_{\rm sys}) ×\times 10−6^{-6}. The first errors denotes the statistical error and the second the systematic uncertainties. A⊄_\perp arises from the imaginary part of the two-photon exchange amplitude and is zero in the one-photon exchange approximation. From comparison with theoretical estimates of A⊄_\perp we conclude that π\piN-intermediate states give a substantial contribution to the imaginary part of the two-photon amplitude. The contribution from the ground state proton to the imaginary part of the two-photon exchange can be neglected. There is no obvious reason why this should be different for the real part of the two-photon amplitude, which enters into the radiative corrections for the Rosenbluth separation measurements of the electric form factor of the proton.Comment: 4 figures, submitted to PRL on Oct.

    Evidence for Strange Quark Contributions to the Nucleon's Form Factors at Q2Q^2 = 0.108 (GeV/c)2^2

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    We report on a measurement of the parity violating asymmetry in the elastic scattering of polarized electrons off unpolarized protons with the A4 apparatus at MAMI in Mainz at a four momentum transfer value of Q2Q^2 = \Qsquare (GeV/c)2^2 and at a forward electron scattering angle of 30∘<Ξe<40∘^\circ < \theta_e < 40^\circ. The measured asymmetry is ALR(e⃗p)A_{LR}(\vec{e}p) = (\Aphys ±\pm \Deltastatstat_{stat} ±\pm \Deltasystsyst_{syst}) ×\times 10−6^{-6}. The expectation from the Standard Model assuming no strangeness contribution to the vector current is A0_0 = (\Azero ±\pm \DeltaAzero) ×\times 10−6^{-6}. We have improved the statistical accuracy by a factor of 3 as compared to our previous measurements at a higher Q2Q^2. We have extracted the strangeness contribution to the electromagnetic form factors from our data to be GEsG_E^s + \FakGMs GMsG_M^s = \GEsGMs ±\pm \DeltaGEsGMs at Q2Q^2 = \Qsquare (GeV/c)2^2. As in our previous measurement at higher momentum transfer for GEsG_E^s + 0.230 GMsG_M^s, we again find the value for GEsG_E^s + \FakGMs GMsG_M^s to be positive, this time at an improved significance level of 2 σ\sigma.Comment: 4 pages, 3 figure

    Bacterial isolation in samples of goat milk.

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    The aim of this study was to monitor the presence of pathogens causing caprine mastitis during three months in a properties situated in the region of the Zona da Mata of Minas Gerais. The presence of isolated microorganisms of goat milk stresses the importance of prophylaxis measures and control of subclinical mastitis in the flock. That?s because the isolated microorganisms exhibit great importance for public health, as they are possible producers of staphylococcal toxin, and therefore, possible causes of food poisoning

    Online 4D ultrasound guidance for real-time motion compensation by MLC tracking

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    PURPOSE: With the trend in radiotherapy moving toward dose escalation and hypofractionation, the need for highly accurate targeting increases. While MLC tracking is already being successfully used for motion compensation of moving targets in the prostate, current real-time target localization methods rely on repeated x-ray imaging and implanted fiducial markers or electromagnetic transponders rather than direct target visualization. In contrast, ultrasound imaging can yield volumetric data in real-time (3D + time = 4D) without ionizing radiation. The authors report the first results of combining these promising techniques-online 4D ultrasound guidance and MLC tracking-in a phantom. METHODS: A software framework for real-time target localization was installed directly on a 4D ultrasound station and used to detect a 2 mm spherical lead marker inside a water tank. The lead marker was rigidly attached to a motion stage programmed to reproduce nine characteristic tumor trajectories chosen from large databases (five prostate, four lung). The 3D marker position detected by ultrasound was transferred to a computer program for MLC tracking at a rate of 21.3 Hz and used for real-time MLC aperture adaption on a conventional linear accelerator. The tracking system latency was measured using sinusoidal trajectories and compensated for by applying a kernel density prediction algorithm for the lung traces. To measure geometric accuracy, static anterior and lateral conformal fields as well as a 358° arc with a 10 cm circular aperture were delivered for each trajectory. The two-dimensional (2D) geometric tracking error was measured as the difference between marker position and MLC aperture center in continuously acquired portal images. For dosimetric evaluation, VMAT treatment plans with high and low modulation were delivered to a biplanar diode array dosimeter using the same trajectories. Dose measurements with and without MLC tracking were compared to a static reference dose using 3%/3 mm and 2%/2 mm γ-tests. RESULTS: The overall tracking system latency was 172 ms. The mean 2D root-mean-square tracking error was 1.03 mm (0.80 mm prostate, 1.31 mm lung). MLC tracking improved the dose delivery in all cases with an overall reduction in the γ-failure rate of 91.2% (3%/3 mm) and 89.9% (2%/2 mm) compared to no motion compensation. Low modulation VMAT plans had no (3%/3 mm) or minimal (2%/2 mm) residual γ-failures while tracking reduced the γ-failure rate from 17.4% to 2.8% (3%/3 mm) and from 33.9% to 6.5% (2%/2 mm) for plans with high modulation. CONCLUSIONS: Real-time 4D ultrasound tracking was successfully integrated with online MLC tracking for the first time. The developed framework showed an accuracy and latency comparable with other MLC tracking methods while holding the potential to measure and adapt to target motion, including rotation and deformation, noninvasively

    Regulatory T-Cells and Associated Pathways in Metastatic Renal Cell Carcinoma (mRCC) Patients Undergoing DC-Vaccination and Cytokine-Therapy

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    Purpose: To evaluate CD4+CD25+FOXP3+ T regulatory cells (TREG) and associated immune-regulatory pathways in peripheral blood lymphocytes (PBL) of metastatic renal cell carcinoma (mRCC) patients and healthy volunteers. We subsequently investigated the effects of immunotherapy on circulating TREG combining an extensive phenotype examination, DNA methylation analysis and global transcriptome analysis. Design: Eighteen patients with mRCC and twelve volunteers (controls) were available for analysis. TREG phenotype was examined using flow cytometry (FCM). TREG were also quantified by analyzing the epigenetic status of the FOXP3 locus using methylation specific PCR. As a third approach, RNA of the PBL was hybridized to Affymetrix GeneChip Human Gene 1.0 ST Arrays and the gene signatures were explored using pathway analysis. Results We observed higher numbers of TREG in pre-treatment PBL of mRCC patients compared to controls. A significant increase in TREG was detected in all mRCC patients after the two cycles of immunotherapy. The expansion of TREG was significantly higher in non-responders than in responding patients. Methylation specific PCR confirmed the FCM data and circumvented the variability and subjectivity of the FCM method. Gene Set Enrichment Analysis (GSEA) of the microarray data showed significant enrichment of FOXP3 target genes, CTLA-4 and TGF-ß associated pathways in the patient cohort. Conclusion: Immune monitoring of the peripheral blood and tumor tissue is important for a wide range of diseases and treatment strategies. Adoption of methodology for quantifying TREG with the least variability and subjectivity will enhance the ability to compare and interpret findings across studies

    Personalized management strategies in mast cell disorders: ECNM-AIM User's guide for daily clinical practice

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    Mastocytosis is a myeloid neoplasm defined by expansion and focal accumulation of clonal mast cells (MCs) in one or more organs. The disease exhibits a complex pathology and may be complicated by MC activation, bone abnormalities, neurological problems, gastrointestinal symptoms, and/or hematologic progression. The World Health Organization divides mastocytosis into cutaneous forms, systemic mastocytosis (SM) and MC sarcoma. In most patients with SM, somatic mutations in KIT are detected. Patients with indolent SM have a normal to near-normal life expectancy, whereas patients with advanced SM, including aggressive SM and MC leukemia, have a poor prognosis. In those with advanced SM, multiple somatic mutations and an associated hematologic neoplasm may be detected. Mediator-related symptoms can occur in any type of mastocytosis. Symptoms may be mild, severe, or even life-threatening. In patients with severe acute symptoms, an MC activation syndrome may be diagnosed. In these patients, relevant comorbidities include IgE-dependent and IgE-independent allergies. Management of patients with SM is an emerging challenge in daily practice and requires in-depth knowledge and a multidisciplinary and personalized approach with selection of appropriate procedures and interventions. In this article, we review the current knowledge on SM and MC activation syndrome, with emphasis on multidisciplinary aspects in diagnosis and patient-specific management. In addition, we provide a user’s guide for application of markers, algorithms, prognostic scores, and treatments for use in daily practice.This work was supported in part by the Austrian Science Fund (FWF; projects F4704 and P32470-B to P.V.) and the Division of Intramural Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health (NIH) (to M.C.C. and D.D.M.). The content is solely the responsibility of the authors and does not represent the official views of the NIH

    Standards of genetic testing in the diagnosis and prognostication of systemic mastocytosis in 2022: Recommendations of the EU-US cooperative group

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    Mastocytosis comprises rare heterogeneous diseases characterized by an increased accumulation of abnormal mast cells in various organs/tissues. The pathogenesis of mastocytosis is strongly linked to the presence of KIT-activating mutations. In systemic mastocytosis (SM), the most frequent mutation encountered is KIT p.D816V, whose presence constitutes one of the minor diagnostic criteria. Different techniques are used to search and quantify the KIT p.D816V mutant; however, allele-specific quantitative PCR and droplet digital PCR are today the most sensitive. The analysis of the KIT p.D816V allele burden has undeniable interest for diagnostic, prognostic, and therapeutic monitoring. The analysis of non–mast cell hematological compartments in SM is similarly important because KIT p.D816V multilineage involvement is associated with a worse prognosis. In addition, in advanced forms of SM, mutations in genes other than KIT are frequently identified and affect negatively disease outcome and response to therapy. Thus, combined quantitative and sensitive analysis of KIT mutations and next-generation sequencing of other recurrently involved myeloid genes make it possible to better characterize the extent of the affected cellular compartments and additional molecular aberrations, providing a more detailed overview of the complex mutational landscape of SM, in relation with the clinical heterogeneity of the disease. In this article, we report the latest recommendations of the EU-US Cooperative Group presented in September 2020 in Vienna during an international working conference, on the techniques we consider standard to detect and quantify the KIT p.D816V mutant in SM and additional myeloid mutations found in SM subtypes.D.D.M., J.J.L., and M.C.C. were supported by the Division of Intramural Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health. P.V. was supported by the Austrian Science Fund (FWF) (grant nos. F4704-B20 and P32470-B)
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