Brownian motion of black holes in stellar systems with non-Maxwellian distribution for the stars field

A massive black hole at the center of a dense stellar system, such as a globular cluster or a galactic nucleus, is subject to a random walk due gravitational encounters with nearby stars. It behaves as a Brownian particle, since it is much more massive than the surrounding stars and moves much more slowly than they do. If the distribution function for the stellar velocities is Maxwellian, there is a exact equipartition of kinetic energy between the black hole and the stars in the stationary state. However, if the distribution function deviates from a Maxwellian form, the strict equipartition cannot be achieved. The deviation from equipartition is quantified in this work by applying the Tsallis q-distribution for the stellar velocities in a q-isothermal stellar system and in a generalized King model.Comment: Presented at XXVI Int. Astronomical Union General Assembly, Symp. 238, Prague, Czech Republic, Aug 21-25 200

Generalised Space-time and Gauge Transformations

We consider the generalised space-time introduced by the author in 2003 in the context of the non-linear realisation of the semi-direct product of E11 and its first fundamental representation. For all the fields we propose gauge transformations which are compatible with the underlying E11 structure. A crucial role is played by the generalised vielbein that the generalised space-time possess. We work out the explicit form of the gauge transformations, at low levels, in four, five and eleven dimensions.Comment: 33 page

Dynamics of growth differentiation factor 15 in acute heart failure

Aims: Risk stratification in acute heart failure (HF) patients can help to decide therapies and time for discharge. The potential of growth differentiation factor 15 (GDF-15) in HF has been previously shown. We aimed to study the importance of GDF-15-level variations in acute HF patients. Methods and results: We retrospectively evaluated a cohort of patients hospitalized due to acute HF. GDF-15 was measured both at admission and on the discharge day. Patients were followed-up during a 3 year period. The endpoint under analysis was all-cause mortality. GDF-15 variation is equal to [(admission GDF-15 - discharge GDF-15)∕admission GDF-15] × 100. Variation was categorized in levels of increase or decrease of GDF-15. Patients were cross-classified according to admission and discharge GDF-15 cut-off points. A Cox regression analysis was used to assess the prognostic impact of GDF-15 variation and the impact of both admission and discharge GDF-15 according to the cross-classification. We studied a group of 249 patients with high co-morbidity burden. Eighty-one patients died at 1 year and 147 within 3 years. There was a modest decrease in GDF-15 during hospitalization from a median value of 4087 to 3671 ng/mL (P = 0.02). No association existed between GDF-15 variation and mortality. In multivariate analysis, patients with admission GDF-15 ≥ 3500 ng/mL and discharge GDF-15 ≥ 3000 ng/mL had a significantly higher 1 year death risk when compared with the remaining-hazard ratio = 2.59 (95% confidence interval: 1.41-4.76)-and a 3 year 1.76 (95% confidence interval: 1.08-2.87) higher death risk compared with those with both values below the cut-off. Conclusions: Growth differentiation factor 15 decreased during an acute HF hospitalization, but its variation had no prognostic implications. The knowledge of both admission and discharge GDF-15 added meaningful information to patients' risk stratification

Evaluation of medical professionals' knowledge about Q fever.

Aims: evaluate the medical professionals’ knowledge about Q fever, seeking integrative contributions to public health that may favor the formulation of policies and the development of strategies based on a One Health approach. Methods: this is a cross-sectional and quantitative study with data collection through a structured questionnaire applied face-to-face to physicians from various clinical specialties working at the three levels of health care in Brazil. The questionnaire consisted of 25 questions, seven of which were specific to assessing knowledge about Q fever. Univariate and multivariate logistic regression analyses were conducted to assess whether the variables medical specialty, level of health care in which they work, age range and gender were associated with a correct answer to at least one specific question about Q fever. Results: among the 254 physicians included, 236 (92.9%) were unaware of Q fever. Only three (16.6%) of the 18 who correctly answered at least one specific question about the disease had a score of more than 50%. The highest rates of correct answers for at least one question (p < 0.0001) occurred among the medical specialties most related to clinical signs and symptoms or the differential diagnosis of Q fever and among males. It is highlighted that 85.8% of physicians consider Q fever a neglected and underreported disease in Brazil. Additionally, all physicians responded that they were not aware of the One Health approach. Conclusions: the almost total lack of knowledge among medical professionals regarding Q fever reinforces the need for greater disclosure for this zoonosis with a One Health approach in Medical Schools, in Residency Programs and for physicians in general. In addition, the inclusion of Q fever in the national list of notifiable diseases becomes relevant, allowing a better understanding of its epidemiological situation in Brazil. Finally, effective public health actions must be carried out to avoid underdiagnosis and the development of severe cases of the disease

Classification of non-Riemannian doubled-yet-gauged spacetime

Assuming $\mathbf{O}(D,D)$ covariant fields as the `fundamental' variables, Double Field Theory can accommodate novel geometries where a Riemannian metric cannot be defined, even locally. Here we present a complete classification of such non-Riemannian spacetimes in terms of two non-negative integers, $(n,\bar{n})$, $0\leq n+\bar{n}\leq D$. Upon these backgrounds, strings become chiral and anti-chiral over $n$ and $\bar{n}$ directions respectively, while particles and strings are frozen over the $n+\bar{n}$ directions. In particular, we identify $(0,0)$ as Riemannian manifolds, $(1,0)$ as non-relativistic spacetime, $(1,1)$ as Gomis-Ooguri non-relativistic string, $(D{-1},0)$ as ultra-relativistic Carroll geometry, and $(D,0)$ as Siegel's chiral string. Combined with a covariant Kaluza-Klein ansatz which we further spell, $(0,1)$ leads to Newton-Cartan gravity. Alternative to the conventional string compactifications on small manifolds, non-Riemannian spacetime such as $D=10$, $(3,3)$ may open a new scheme of the dimensional reduction from ten to four.Comment: 1+41 pages; v2) Refs added; v3) Published version; v4) Sign error in (2.51) correcte

On the Riemann Tensor in Double Field Theory

Double field theory provides T-duality covariant generalized tensors that are natural extensions of the scalar and Ricci curvatures of Riemannian geometry. We search for a similar extension of the Riemann curvature tensor by developing a geometry based on the generalized metric and the dilaton. We find a duality covariant Riemann tensor whose contractions give the Ricci and scalar curvatures, but that is not fully determined in terms of the physical fields. This suggests that \alpha' corrections to the effective action require \alpha' corrections to T-duality transformations and/or generalized diffeomorphisms. Further evidence to this effect is found by an additional computation that shows that there is no T-duality invariant four-derivative object built from the generalized metric and the dilaton that reduces to the square of the Riemann tensor.Comment: 36 pages, v2: minor changes, ref. added, v3: appendix on frame formalism added, version to appear in JHE