142 research outputs found
Flux Tube Zero-Point Motion, Hadronic Charge Radii, and Hybrid Meson Production Cross Sections
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
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
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
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
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
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 exotics
We estimate the kinematic dependence of the exclusive photo-- and
electroproduction of exotic mesons due to exchange. We
show that the kinematic dependence is largely independent of the exotic meson
form factor, which is explicitly derived for a 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 photoproduction and implications for searches of exotic meson
We analyze the process at low momentum
transfer focusing on a possibility of production of an exotic
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
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
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Reduction of diagnostic and treatment delays reduces rifampicin-resistant tuberculosis mortality in Rwanda
YesSETTING: In 2005, in response to the increasing prevalence of rifampicin-resistant tuberculosis (RR-TB) and poor treatment outcomes, Rwanda initiated the programmatic management of RR-TB, including expanded access to systematic rifampicin drug susceptibility testing (DST) and standardised treatment.OBJECTIVE: To describe trends in diagnostic and treatment delays and estimate their effect on RR-TB mortality.DESIGN: Retrospective analysis of individual-level data including 748 (85.4%) of 876 patients diagnosed with RR-TB notified to the World Health Organization between 1 July 2005 and 31 December 2016 in Rwanda. Logistic regression was used to estimate the effect of diagnostic and therapeutic delays on RR-TB mortality.RESULTS: Between 2006 and 2016, the median diagnostic delay significantly decreased from 88 days to 1 day, and the therapeutic delay from 76 days to 3 days. Simultaneously, RR-TB mortality significantly decreased from 30.8% in 2006 to 6.9% in 2016. Total delay in starting multidrug-resistant TB (MDR-TB) treatment of more than 100 days was associated with more than two-fold higher odds for dying. When delays were long, empirical RR-TB treatment initiation was associated with a lower mortality.CONCLUSION: The reduction of diagnostic and treatment delays reduced RR-TB mortality. We anticipate that universal testing for RR-TB, short diagnostic and therapeutic delays and effective standardised MDR-TB treatment will further decrease RR-TB mortality in Rwanda
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