142 research outputs found

    Flux Tube Zero-Point Motion, Hadronic Charge Radii, and Hybrid Meson Production Cross Sections

    Get PDF
    Flux tube zero-point motion produces quark displacements transverse to the flux tube which make significant contributions to hadronic charge radii. In heavy quark systems, these contributions can be related by Bjorken's sum rule to the rates for semileptonic decay to hybrid mesons. This connection can be generalized to other leptoproduction processes, where transverse contributions to elastic form factor slopes are related to the cross sections for the production of the associated hybrid states. I identify the flux tube overlap integral responsible for these effects as the strong QCD analogue of the Sudakov form factor of perturbative QCD.Comment: 16 pages, revised to clarify some points and to improve and correct the notation for the flux tube wave function

    Preliminary Results from Recent Measurements of the Antiprotonic Helium Hyperfine Structure

    Full text link
    We report on preliminary results from a systematic study of the hyperfine (HF) structure of antiprotonic helium. This precise measurement which was commenced in 2006, has now been completed. Our initial analysis shows no apparent density or power dependence and therefore the results can be averaged. The statistical error of the observable M1 transitions is a factor of 60 smaller than that of three body quantum electrodynamic (QED) calculations, while their difference has been resolved to a precision comparable to theory (a factor of 10 better than our first measurement). This difference is sensitive to the antiproton magnetic moment and agreement between theory and experiment would lead to an increased precision of this parameter, thus providing a test of CPT invariance.Comment: 6 pages, 4 figure

    A Simple Empirically Motivated Template for the Unresolved Thermal Sunyaev-Zeldovich Effect

    Get PDF
    We develop a model for the power spectrum of unresolved clusters of galaxies arising from the thermal Sunyaev-Zeldovich (tSZ) effect. The model is based on a'universal' gas pressure profile constrained by X-ray observations and includes a parameter to describe departures from self-similar evolution. The model is consistent with recent Planck observations of the tSZ effect for X-ray clusters with redshifts z<1 and reproduces the low amplitude for the tSZ inferred from recent ground based observations. By adjusting two free parameters, we are able to reproduce the tSZ power spectra from recent numerical simulations to an accuracy that is well within theoretical uncertainties. Our model provides a simple, empirically motivated tSZ template that may be useful for the analysis of new experiments such as Planck.Comment: 6 pages 4 figure

    Brief report: active HIV case finding in the city of Kigali, Rwanda: assessment of voluntary assisted partner notification modalities to detect undiagnosed HIV infections

    Get PDF
    BACKGROUND: Voluntary assisted partner notification (VAPN) services that use contract, provider, or dual referral modalities may be efficient to identify individuals with undiagnosed HIV infection. We aimed to assess the relative effectiveness of VAPN modalities in identifying undiagnosed HIV infections. SETTING: VAPN was piloted in 23 health facilities in Kigali, Rwanda. METHODS: We identified individuals with a new HIV diagnosis before antiretroviral therapy initiation or individuals on antiretroviral therapy (index cases), who reported having had sexual partners with unknown HIV status, to assess the association between referral modalities and the odds of identifying HIV-positive partners using a Bayesian hierarchical logistic regression model. We adjusted our model for important factors identified through a Bayesian variable selection. RESULTS: Between October 2018 and December 2019, 6336 index cases were recruited, leading to the testing of 7690 partners. HIV positivity rate was 7.1% (546/7690). We found no association between the different referral modalities and the odds of identifying HIV-positive partners. Notified partners of male individuals (adjusted odds ratio 1.84; 95% credible interval: 1.50 to 2.28) and index cases with a new HIV diagnosis (adjusted odds ratio 1.82; 95% credible interval: 1.45 to 2.30) were more likely to be infected with HIV. CONCLUSION: All 3 VAPN modalities were comparable in identifying partners with HIV. Male individuals and newly diagnosed index cases were more likely to have partners with HIV. HIV-positive yield from index testing was higher than the national average and should be scaled up to reach the first UNAIDS-95 target by 2030

    A maChine and deep Learning Approach to predict pulmoNary hyperteNsIon in newbornS with congenital diaphragmatic Hernia (CLANNISH): Protocol for a retrospective study

    Get PDF
    Introduction Outcome predictions of patients with congenital diaphragmatic hernia (CDH) still have some limitations in the prenatal estimate of postnatal pulmonary hypertension (PH). We propose applying Machine Learning (ML), and Deep Learning (DL) approaches to fetuses and newborns with CDH to develop forecasting models in prenatal epoch, based on the integrated analysis of clinical data, to provide neonatal PH as the first outcome and, possibly: Favorable response to fetal endoscopic tracheal occlusion (FETO), need for Extracorporeal Membrane Oxygenation (ECMO), survival to ECMO, and death. Moreover, we plan to produce a (semi)automatic fetus lung segmentation system in Magnetic Resonance Imaging (MRI), which will be useful during project implementation but will also be an important tool itself to standardize lung volume measures for CDH fetuses. Methods and analytics Patients with isolated CDH from singleton pregnancies will be enrolled, whose prenatal checks were performed at the Fetal Surgery Unit of the Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico (Milan, Italy) from the 30th week of gestation. A retrospective data collection of clinical and radiological variables from newborns' and mothers' clinical records will be performed for eligible patients born between 01/01/2012 and 31/12/2020. The native sequences from fetal magnetic resonance imaging (MRI) will be collected. Data from different sources will be integrated and analyzed using ML and DL, and forecasting algorithms will be developed for each outcome. Methods of data augmentation and dimensionality reduction (feature selection and extraction) will be employed to increase sample size and avoid overfitting. A software system for automatic fetal lung volume segmentation in MRI based on the DL 3D U-NET approach will also be developed. Ethics and dissemination This retrospective study received approval from the local ethics committee (Milan Area 2, Italy). The development of predictive models in CDH outcomes will provide a key contribution in disease prediction, early targeted interventions, and personalized management, with an overall improvement in care quality, resource allocation, healthcare, and family savings. Our findings will be validated in a future prospective multicenter cohort study

    Improved Study of the Antiprotonic Helium Hyperfine Structure

    Get PDF
    We report the initial results from a systematic study of the hyperfine (HF) structure of antiprotonic helium (n,l) = (37,~35) carried out at the Antiproton Decelerator (AD) at CERN. We performed a laser-microwave-laser resonance spectroscopy using a continuous wave (cw) pulse-amplified laser system and microwave cavity to measure the HF transition frequencies. Improvements in the spectral linewidth and stability of our laser system have increased the precision of these measurements by a factor of five and reduced the line width by a factor of three compared to our previous results. A comparison of the experimentally measured transition frequencies with three body QED calculations can be used to determine the antiproton spin magnetic moment, leading towards a test of CPT invariance.Comment: 14 pages 9 figure

    Photo-- and Electroproduction of JPC=1+J^{PC}=1^{-+} exotics

    Get PDF
    We estimate the kinematic dependence of the exclusive photo-- and electroproduction of JPC=1+J^{PC}=1^{-+} exotic mesons due to π\pi exchange. We show that the kinematic dependence is largely independent of the exotic meson form factor, which is explicitly derived for a 1+1^{-+} isovector hybrid meson in the flux-tube model of Isgur and Paton. The relevance to experiments currently planned at Jefferson Lab is indicated.Comment: 15 pages, latex, epsf, 8 postscript figure

    Charge exchange ρ0π+\rho^0 \pi^+ photoproduction and implications for searches of exotic meson

    Full text link
    We analyze the process γ+pρ0π+n\vec \gamma +p\to \rho^0 \pi^{+}n at low momentum transfer focusing on a possibility of production of an exotic JPC=1+J^{PC}=1^{-+} meson state. In particular we discuss polarization observables and conclude that linear photon polarization is instrumental for separating of the exotic wave.Comment: 23 pages, 6 figure

    Formyl Peptide Receptor as a Novel Therapeutic Target for Anxiety-Related Disorders

    Get PDF
    Formyl peptide receptors (FPR) belong to a family of sensors of the immune system that detect microbe-associated molecules and inform various cellular and sensorial mechanisms to the presence of pathogens in the host. Here we demonstrate that Fpr2/3-deficient mice show a distinct profile of behaviour characterised by reduced anxiety in the marble burying and light-dark box paradigms, increased exploratory behaviour in an open-field, together with superior performance on a novel object recognition test. Pharmacological blockade with a formyl peptide receptor antagonist, Boc2, in wild type mice reproduced most of the behavioural changes observed in the Fpr2/3(-/-) mice, including a significant improvement in novel object discrimination and reduced anxiety in a light/dark shuttle test. These effects were associated with reduced FPR signalling in the gut as shown by the significant reduction in the levels of p-p38. Collectively, these findings suggest that homeostatic FPR signalling exerts a modulatory effect on anxiety-like behaviours. These findings thus suggest that therapies targeting FPRs may be a novel approach to ameliorate behavioural abnormalities present in neuropsychiatric disorders at the cognitive-emotional interface
    corecore