553 research outputs found
Gravitomagnetism in Metric Theories: Analysis of Earth Satellites Results, and its Coupling with Spin
Employing the PPN formalism the gravitomagnetic field in different metric
theories is considered in the analysis of the LAGEOS results. It will be shown
that there are several models that predict exactly the same effect that general
relativity comprises. In other words, these Earth satellites results can be
taken as experimental evidence that the orbital angular momentum of a body does
indeed generate space--time geometry, notwithstanding they do not endow general
relativity with an outstanding status among metric theories. Additionally the
coupling spin--gravitomagnetic field is analyzed with the introduction of the
Rabi transitions that this field produces on a quantum system with spin 1/2.
Afterwards, a continuous measurement of the energy of this system is
introduced, and the consequences upon the corresponding probabilities of the
involved gravitomagnetic field will be obtained. Finally, it will be proved
that these proposals allows us, not only to confront against future experiments
the usual assumption of the coupling spin--gravotimagnetism, but also to
measure some PPN parameters and to obtain functional dependences among them.Comment: 10 page
Docemur docemus:peer-assisted learning improves the knowledge gain of tutors in the highest quartile of achievement but not those in the lowest quartile
A spatially-VSL gravity model with 1-PN limit of GRT
A scalar gravity model is developed according the 'geometric conventionalist'
approach introduced by Poincare (Einstein 1921, Poincare 1905, Reichenbach
1957, Gruenbaum1973). In principle this approach allows an alternative
interpretation and formulation of General Relativity Theory (GRT), with
distinct i) physical congruence standard, and ii) gravitation dynamics
according Hamilton-Lagrange mechanics, while iii) retaining empirical
indistinguishability with GRT. In this scalar model the congruence standards
have been expressed as gravitationally modified Lorentz Transformations
(Broekaert 2002). The first type of these transformations relate quantities
observed by gravitationally 'affected' (natural geometry) and 'unaffected'
(coordinate geometry) observers and explicitly reveal a spatially variable
speed of light (VSL). The second type shunts the unaffected perspective and
relates affected observers, recovering i) the invariance of the locally
observed velocity of light, and ii) the local Minkowski metric (Broekaert
2003). In the case of a static gravitation field the model retrieves the
phenomenology implied by the Schwarzschild metric. The case with proper source
kinematics is now described by introduction of a 'sweep velocity' field w: The
model then provides a hamiltonian description for particles and photons in full
accordance with the first Post-Newtonian approximation of GRT (Weinberg 1972,
Will 1993).Comment: v1: 11 pages, GR17 conf. paper, Dublin 2004, v2: WEP issue solved,
section on acceleration transformation added, text improved, more references,
same results, v3: typos removed, footnotes, added and references updated, v4:
appendix added, improved tex
Grp78 Heterozygosity Promotes Adaptive Unfolded Protein Response and Attenuates Diet-Induced Obesity and Insulin Resistance
The Horizon for Treating Cutaneous Vascular Lesions
Dermatologists encounter a wide range of cutaneous vascular lesions, including infantile hemangiomas, port-wine stain birthmarks, arteriovenous malformations, venous malformations, Kaposi sarcomas, angiosarcomas, and angiofibromas. Current treatment modalities to reduce these lesions include topical and/or intralesional steroids, laser therapy, surgical resection, and endovascular therapy. However, each method has limitations owing to recurrence, comorbidities, toxicity, or lesion location. Photodynamic therapy, antiangiogenic therapy, and evolving methods of sclerotherapy are promising areas of development that may mitigate limitations of current treatments and offer exciting options for patients and their physicians
Typical asymmetry in the hemispheric activation during an fMRI verbal comprehension paradigm is related to better performance in verbal and non-verbal tasks in patients with epilepsy
Chronic exposure to seizures in patients with left hemisphere (LH) epileptic focus could favor higher activation in the contralateral hemisphere during language processing, but the cognitive effects of this remain unclear. This study assesses the relationship between asymmetry in hemispheric activation during language fMRI and performance in verbal and non-verbal tasks. Whereas prior studies primarily used fMRI paradigms that favor frontal lobe activation and less prominent activation of the medial or superior temporal lobes, we used a verbal comprehension paradigm previously demonstrated to activate reliably receptive language areas. Forty-seven patients with drug-resistant epilepsy candidates for surgery underwent a multidisciplinary assessment, including a comprehensive neuropsychological evaluation and an fMRI verbal comprehension paradigm. Patients were distributed in two groups depending on laterality indexes (LI): typical hemispheric asymmetry (unilateral left activation preponderance; n = 23) and atypical hemispheric asymmetry (bilateral or unilateral right preponderance; n = 24). Right-handedness and right hemisphere (RH) focus were significant predictors of typical asymmetry. Patients with typical activation pattern presented better performance intelligence quotient and verbal learning than patients with atypical hemispheric asymmetry (for all, p < 0.014). Patients with LH focus had more frequently atypical hemispheric asymmetry than patients with RH focus (p = 0.05). Specifically, they showed lower LI and this was related to worse performance in verbal and non-verbal tasks. In conclusion, an increased activation of homologous RH areas for verbal comprehension processing could imply a competition of cognitive resources in the performance of the same task, disrupting cognitive performance
Dynamical Boson Stars
The idea of stable, localized bundles of energy has strong appeal as a model
for particles. In the 1950s John Wheeler envisioned such bundles as smooth
configurations of electromagnetic energy that he called {\em geons}, but none
were found. Instead, particle-like solutions were found in the late 1960s with
the addition of a scalar field, and these were given the name {\em boson
stars}. Since then, boson stars find use in a wide variety of models as sources
of dark matter, as black hole mimickers, in simple models of binary systems,
and as a tool in finding black holes in higher dimensions with only a single
killing vector. We discuss important varieties of boson stars, their dynamic
properties, and some of their uses, concentrating on recent efforts.Comment: 79 pages, 25 figures, invited review for Living Reviews in
Relativity; major revision in 201
Retention and mortality outcomes from a community-supported public–private HIV treatment programme in Myanmar
Introduction: There is a growing interest in the potential contribution the private sector can make towards increasing access to antiretroviral therapy (ART) in low- and middle-income settings. This article describes a public–private partnership that was developed to expand HIV care capacity in Yangon, Myanmar. The partnership was between private sector general practitioners (GPs) and a community-based non-governmental organization (International HIV/AIDS Alliance). Methods: Retrospective analysis of 2119 patient records dating from March 2009 to April 2015 was conducted. Outcomes assessed were immunological response, loss to follow-up, all-cause mortality, and alive and retained in care. Follow-up time was calculated from the date of registration to the date of death, loss to follow-up, transfer out, or if still alive and known to be in care, until April 2015. Cox proportional hazards model was used to identify predictors of loss to follow-up and mortality. Kaplan–Meier survival analysis was used to estimate survival function of being alive and retained in care. Results: The median number of patients for each of the 16 GPs was 42 (interquartile range (IQR): 25–227), and the median follow-up period was 13 months. The median patient age was 35 years (IQR: 30–41); 56.6% were men, 62 and 11.8% were in WHO Stage III and Stage IV at registration, respectively; median CD4 count at registration was 177 cells/mm3; and 90.7% were on ART in April 2015. The median CD4 count at registration increased from 122 cells/mm3 in 2009 to 194 cells/mm3 in 2014. Among patients on ART, CD4 counts increased from a median of 187 cells/mm3 at registration to 436 cells/mm3 at 36 months. The median time to initiation of ART among eligible patients was 29 days, with 93.8% of eligible patients being initiated on ART within 90 days. Overall, 3.3% patients were lost to follow-up, 4.2% transferred out to other health facilities, and 8.3% died during the follow-up period. Crude mortality rate was 48.6/1000 person-years; 42% (n=74) of deaths occurred during the pre-ART period and 39.8% (n=70) occurred during the first six months of ART. Of those who died during the pre-ART period, 94.5% were eligible for ART. In multivariate regression, baseline CD4 count and ART status were independent predictors of mortality, whereas ART status, younger age and patient volumes per provider were predictors of loss to follow-up. Probability of being alive and retained in care at six months was 96.8% among those on ART, 38.5% among pre-ART but eligible patients, and 20.0% among ART-ineligible patients. Conclusions: Effectively supported private sector GPs successfully administered and monitored ART in Myanmar, suggesting that community-supported private sector partnerships can contribute to expansion of HIV treatment and care capacity. To further improve patient outcomes, early testing and initiation of ART, combined with close clinical monitoring and support during the initial periods of enrolling in treatment and care, are required
Measurement of the Bottom-Strange Meson Mixing Phase in the Full CDF Data Set
We report a measurement of the bottom-strange meson mixing phase \beta_s
using the time evolution of B0_s -> J/\psi (->\mu+\mu-) \phi (-> K+ K-) decays
in which the quark-flavor content of the bottom-strange meson is identified at
production. This measurement uses the full data set of proton-antiproton
collisions at sqrt(s)= 1.96 TeV collected by the Collider Detector experiment
at the Fermilab Tevatron, corresponding to 9.6 fb-1 of integrated luminosity.
We report confidence regions in the two-dimensional space of \beta_s and the
B0_s decay-width difference \Delta\Gamma_s, and measure \beta_s in [-\pi/2,
-1.51] U [-0.06, 0.30] U [1.26, \pi/2] at the 68% confidence level, in
agreement with the standard model expectation. Assuming the standard model
value of \beta_s, we also determine \Delta\Gamma_s = 0.068 +- 0.026 (stat) +-
0.009 (syst) ps-1 and the mean B0_s lifetime, \tau_s = 1.528 +- 0.019 (stat) +-
0.009 (syst) ps, which are consistent and competitive with determinations by
other experiments.Comment: 8 pages, 2 figures, Phys. Rev. Lett 109, 171802 (2012
A proteomic and transcriptional view of acidogenic and solventogenic steady-state cells of Clostridium acetobutylicum in a chemostat culture
The complex changes in the life cycle of Clostridium acetobutylicum, a promising biofuel producer, are not well understood. During exponential growth, sugars are fermented to acetate and butyrate, and in the transition phase, the metabolism switches to the production of the solvents acetone and butanol accompanied by the initiation of endospore formation. Using phosphate-limited chemostat cultures at pH 5.7, C. acetobutylicum was kept at a steady state of acidogenic metabolism, whereas at pH 4.5, the cells showed stable solvent production without sporulation. Novel proteome reference maps of cytosolic proteins from both acidogenesis and solventogenesis with a high degree of reproducibility were generated. Yielding a 21% coverage, 15 protein spots were specifically assigned to the acidogenic phase, and 29 protein spots exhibited a significantly higher abundance in the solventogenic phase. Besides well-known metabolic proteins, unexpected proteins were also identified. Among these, the two proteins CAP0036 and CAP0037 of unknown function were found as major striking indicator proteins in acidogenic cells. Proteome data were confirmed by genome-wide DNA microarray analyses of the identical cultures. Thus, a first systematic study of acidogenic and solventogenic chemostat cultures is presented, and similarities as well as differences to previous studies of batch cultures are discussed
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