Static spherically symmetric Einstein-Vlasov shells made up of particles with a discrete set of values of their angular momentum

In this paper we study static spherically symmetric Einstein-Vlasov shells, made up of equal mass particles, where the angular momentum L of particles takes values only on a discrete finite set. We consider first the case where there is only one value of L, and prove their existence by constructing explicit examples. Shells with either hollow or black hole interiors have finite thickness. Of particular interest is the thin shell limit of these systems and we study its properties using both numerical and analytic arguments to compare with known results. The general case of a set of values of L is also considered and the particular case where L takes only two values is analyzed, and compared with the corresponding thin shell limit already given in the literature, finding good agreement in all cases.Comment: Comments: 16 pages, 5 figures. Section on thin shell limit revised. References adde

The effect of radiative gravitational modes on the dynamics of a cylindrical shell of counter rotating particles

In this paper we consider some aspects of the relativistic dynamics of a cylindrical shell of counter rotating particles. In some sense these are the simplest systems with a physically acceptable matter content that display in a well defined sense an interaction with the radiative modes of the gravitational field. These systems have been analyzed previously, but in most cases resorting to approximations, or considering a particular form for the initial value data. Here we show that there exists a family of solutions where the space time inside the shell is flat and the equation of motion of the shell decouples completely from the gravitational modes. The motion of the shell is governed by an equation of the same form as that of a particle in a time independent one dimensional potential. We find that under appropriate initial conditions one can have collapsing, bounded periodic, and unbounded motions. We analyze and solve also the linearized equations that describe the dynamics of the system near a stable static solutions, keeping a regular interior. The surprising result here is that the motion of the shell is completely determined by the configuration of the radiative modes of the gravitational field. In particular, there are oscillating solutions for any chosen period, in contrast with the "approximately Newtonian plus small radiative corrections" motion expectation. We comment on the physical meaning of these results and provide some explicit examples. We also discuss the relation of our results to the initial value problem for the linearized dynamics of the shell

Perturbative evolution of the static configurations, quasinormal modes and quasi normal ringing in the Apostolatos - Thorne cylindrical shell model

We study the perturbative evolution of the static configurations, quasinormal modes and quasi normal ringing in the Apostolatos - Thorne cylindrical shell model. We consider first an expansion in harmonic modes and show that it provides a complete solution for the characteristic value problem for the finite perturbations of a static configuration. As a consequence of this completeness we obtain a proof of the stability of static solutions under this type of perturbations. The explicit expression for the mode expansion are then used to obtain numerical values for some of the quasi normal mode complex frequencies. Some examples involving the numerical evaluation of the integral mode expansions are described and analyzed, and the quasi normal ringing displayed by the solutions is found to be in agreement with quasi normal modes found previously. Going back to the full relativistic equations of motion we find their general linear form by expanding to first order about a static solution. We then show that the resulting set of coupled ordinary and partial differential equations for the dynamical variables of the system can be used to set an initial plus boundary values problem, and prove that there is an associated positive definite constant of the motion that puts absolute bounds on the dynamic variables of the system, establishing the stability of the motion of the shell under arbitrary, finite perturbations. We also show that the problem can be solved numerically, and provide some explicit examples that display the complete agreement between the purely numerical evolution and that obtained using the mode expansion, in particular regarding the quasi normal ringing that results in the evolution of the system. We also discuss the relation of the present work to some recent results on the same model that have appeared in the literature.Comment: 27 pages, 7 figure

Self-gravitating splitting thin shells

In this paper we show that thin shells in spherically symmetric spacetimes, whose matter content is described by a pair of non-interacting spherically symmetric matter fields, generically exhibit instability against an infinitesimal separation of its constituent fields. We give explicit examples and construct solutions that represent a shell that splits into two shells. Then we extend those results for 5-dimensional Schwarzschild-AdS bulk spacetimes, which is a typical scenario for brane-world models, and show that the same kind of stability analysis and splitting solution can be constructed. We find that a widely proposed family of brane-world models are extremely unstable in this sense. Finally, we discuss possible interpretations of these features and their relation to the initial value problem for concentrated sources.Comment: 18 pages, 3 figure

Psychosocial stress and inflammation driving tryptophan breakdown in children and adolescents : a cross-sectional analysis of two cohorts

Background: Tryptophan breakdown is an important mechanism in several diseases e.g. inflammation and stress induced inflammation have been associated with the development of depression via enhanced tryptophan breakdown. Depression is a major public health problem which commonly starts during adolescence, thus identifying underlying mechanisms during early life is crucial in prevention. The aim of this work was to verify whether independent and interacting associations of psychosocial stress and inflammation on tryptophan breakdown already exist in children and adolescents as a vulnerable age group. Methods: Two cross-sectional population-based samples of children/adolescents (8-18 y) were available: 315 from the European HELENA study and 164 from the Belgian ChiBS study. In fasting serum samples, tryptophan, kynurenine, kynurenic acid, C-reactive protein (CRP), interleukin (IL)-6, tumor necrosis factor (TNF)-alpha, interferon (IFN)-gamma, soluble vascular adhesion molecule 1 (sVCAM1) and soluble intercellular adhesion molecule 1 (sICAM1) were measured. Psychological stress was measured by stress reports (subjective) and cortisol (objective - awakening salivary cortisol or hair cortisol). Linear regressions with stress or inflammation as predictor were adjusted for age, sex, body mass index, puberty, socio-economic status and country. Results: In both cohorts, inflammation as measured by higher levels of CRP, sVCAM1 and sICAM1 was associated with kynurenine/tryptophan ratio and thus enhanced tryptophan breakdown (beta: 0.145-0.429). Psychological stress was only associated with tryptophan breakdown in the presence of higher inflammatory levels (TNF-alpha in both populations). Conclusions: Inflammatory levels were replicable key in enhancing tryptophan breakdown along the kynurenine pathway, even at young age and in a non-clinical sample. The stress-inflammation interaction indicated that only the stress exposures inducing higher inflammatory levels (or in an already existing inflammatory status) were associated with more tryptophan breakdown. This data further contributes to our understanding of pathways to disease development, and may help identifying those more likely to develop stress or inflammation-related illnesses

Effects of the Menstrual Cycle on Jumping, Sprinting and Force-Velocity Profiling in Resistance-Trained Women: A Preliminary Study

The aim of this study was to examine the effects of the menstrual cycle on vertical jumping, sprint performance and force-velocity profiling in resistance-trained women. A group of resistancetrained eumenorrheic women (n = 9) were tested in three phases over the menstrual cycle: bleeding phase, follicular phase, and luteal phase (i.e., days 1–3, 7–10, and 19–21 of the cycle, respectively). Each testing phase consisted of a battery of jumping tests (i.e., squat jump [SJ], countermovement jump [CMJ], drop jump from a 30 cm box [DJ30], and the reactive strength index) and 30 m sprint running test. Two different applications for smartphone (My Jump 2 and My Sprint) were used to record the jumping and sprinting trials, respectively, at high speed (240 fps). The repeated measures ANOVA reported no significant differences (p ≥ 0.05, ES < 0.25) in CMJ, DJ30, reactive strength index and sprint times between the different phases of the menstrual cycle. A greater SJ height performance was observed during the follicular phase compared to the bleeding phase (p = 0.033, ES = −0.22). No differences (p ≥ 0.05, ES < 0.45) were found in the CMJ and sprint force-velocity profile over the different phases of the menstrual cycle. Vertical jump, sprint performance and the force-velocity profiling remain constant in trained women, regardless of the phase of the menstrual cycle.Pre-competitive Projects for Early Stage Researchers Programme from the University of Granada (ref: PPJIA2020.03

Short Duration of Antibiotic Therapy in Hospitalized Patients with Community-Acquired Pneumonia: Results from the CAPO International Cohort Study

Introduction: Experts suggest a short duration of antibiotic therapy (DOT) in responding patients with community-acquired pneumonia (CAP). The aim of this study was to evaluate clinical outcomes after hospital discharge among patients treated with short-course antibiotic therapy (SCT) vs. long-course antibiotic therapy (LCT) for CAP. Methods: A secondary analysis of the Community-Acquired Pneumonia Organization (CAPO) database from January 2007 to June 2013 was performed, including hospitalized CAP patients who reached clinical stability within 5 days. Two groups were identified: patients who were treated with antibiotic therapy for a total duration of 5 days or less (SCT Group) vs. longer than 5 days (LCT Group). Rehospitalization and mortality were evaluated at 30 days after discharge. Results: 1,849 patients were enrolled (58% males; median age: 65 years), 179 (10%) were included in the SCT and 1,670 (90%) in the LTC group. Median DOT was 5 days in the SCT and 10 days in the LTC group, p Conclusions: A duration of antibiotic therapy of ≤ 5 days does not adversely impact clinical outcomes at 30-days after discharge compared to \u3e5 days in patients who reached early clinical stability

Beta-hemolytic Streptococcus dysgalactiae strains isolated from horses are a genetically distinct population within the Streptococcus dysgalactiae taxon

The pathogenic role of beta-hemolytic Streptococcus dysgalactiae in the equine host is increasingly recognized. A collection of 108 Lancefield group C (n = 96) or L (n = 12) horse isolates recovered in the United States and in three European countries presented multilocus sequence typing (MLST) alleles, sequence types and emm types (only 56% of the isolates could be emm typed) that were, with few exceptions, distinct from those previously found in human Streptococcus dysgalactiae subsp. equisimilis. Characterization of a subset of horse isolates by multilocus sequence analysis (MLSA) and 16S rRNA gene sequence showed that most equine isolates could also be differentiated from S. dysgalactiae strains from other animal species, supporting the existence of a horse specific genomovar. Draft genome information confirms the distinctiveness of the horse genomovar and indicates the presence of potentially horse-specific virulence factors. While this genomovar represents most of the isolates recovered from horses, a smaller MLST and MLSA defined sub-population seems to be able to cause infections in horses, other animals and humans, indicating that transmission between hosts of strains belonging to this group may occur

Discrete Anatomical Coordinates for Speech Production and Synthesis

The sounds of all languages are described by a finite set of symbols, which are extracted from the continuum of sounds produced by the vocal organ. How the discrete phonemic identity is encoded in the continuous movements producing speech remains an open question for the experimental phonology. In this work, this question is assessed by using Hall-effect transducers and magnets—mounted on the tongue, lips, and jaw—to track the kinematics of the oral tract during the vocalization of vowel-consonant-vowel structures. Using a threshold strategy, the time traces of the transducers were converted into discrete motor coordinates unambiguously associated with the vocalized phonemes. Furthermore, the signals of the transducers combined with the discretization strategy were used to drive a low-dimensional vocal model capable of synthesizing intelligible speech. The current work not only assesses a relevant inquiry of the biology of language, but also demonstrates the performance of the experimental technique to monitor the displacement of the main articulators of the vocal tract while speaking. This novel electronic device represents an economic and portable option to the standard systems used to study the vocal tract movements