Transition redshift in f(T)f(T) cosmology and observational constraints

We extract constraints on the transition redshift $z_{tr}$, determining theonset of cosmic acceleration, predicted by an effective cosmographicconstruction, in the framework of $f(T)$ gravity. In particular, employingcosmography we obtain bounds on the viable $f(T)$ forms and their derivatives.Since this procedure is model independent, as long as the scalar curvature isfixed, we are able to determine intervals for $z_{tr}$. In this way weguarantee that the Solar-System constraints are preserved and moreover weextract bounds on the transition time and the free parameters of the scenario.We find that the transition redshifts predicted by $f(T)$ cosmology, althoughcompatible with the standard $\Lambda$CDM predictions, are slightly smaller.Finally, in order to obtain observational constraints on $f(T)$ cosmology, weperform a Monte Carlo fitting using supernova data, involving the most recentunion 2.1 data set

Gravitational repulsive effects in 3D regular black holes

In this work, we consider the effects of repulsive gravity in an invariant way for four static 3D regular black holes, using the eigenvalues of the Riemann curvature tensor, the Ricci scalar, and the strong energy conditions. The eigenvalues of the solutions are non-vanishing asymptotically (in asymptotically AdS) and increase as the source of gravity is approached, providing a radius at which the passage from attractive to repulsive gravity might occur. We compute the onsets and the regions of repulsive gravity and conclude that the regular behavior of the solutions at the origin of coordinates can be interpreted as due to the presence of repulsive gravity, which also turns out to be related with the violation of the strong energy condition. We showed that in all of the solutions for the allowed region of parameters, gravity changes its sign, but the repulsive regions only for the non-logarithmic solution are affected by the mass that generates the regular black hole. The repulsive regions for the logarithmic solutions are dependent on electric charge and the AdS$_{3}$ length. The implications and physical consequences of these results are discussed in detail.Comment: 12 pages, 5 figure

Two-to-one resonant multi-modal dynamics of horizontal/inclined cables. Part I : theoretical formulation and model validation

This paper is first of the two papers dealingwith analytical investigation of resonant multimodal dynamics due to 2:1 internal resonances in the finite-amplitude free vibrations of horizontal/inclined cables. Part I deals with theoretical formulation and validation of the general cable model. Approximate nonlinear partial differential equations of 3-D coupled motion of small sagged cables - which account for both spatio-temporal variation of nonlinear dynamic tension and system asymmetry due to inclined sagged configurations - are presented. A multidimensional Galerkin expansion of the solution ofnonplanar/planar motion is performed, yielding a complete set of system quadratic/cubic coefficients. With the aim of parametrically studying the behavior of horizontal/inclined cables in Part II [25], a second-order asymptotic analysis under planar 2:1 resonance is accomplished by the method of multiple scales. On accounting for higher-order effectsof quadratic/cubic nonlinearities, approximate closed form solutions of nonlinear amplitudes, frequencies and dynamic configurations of resonant nonlinear normal modes reveal the dependence of cable response on resonant/nonresonant modal contributions. Depending on simplifying kinematic modeling and assigned system parameters, approximate horizontal/inclined cable models are thoroughly validated by numerically evaluating statics and non-planar/planar linear/non-linear dynamics against those of the exact model. Moreover, the modal coupling role and contribution of system longitudinal dynamics are discussed for horizontal cables, showing some meaningful effects due to kinematic condensation

Is surgical debridement necessary in the diabetic foot treated with photodynamic therapy?

Background: Diabetic patients are susceptible to developing foot ulcerswith serious complications such as osteomyelitis and amputations. Treatment approaches are still empirical and the benefit of usual procedures such as surgical debridement has not been properly evaluated. Photodynamic Therapy (PDT) is a non-invasive and highly efficient method for the treatment of the diabetic foot, being able to eradicate the infection and to stimulate healing, decreasing considerably the amputation risk. In the day-to-day practice of our service, we have been faced with the question whether debridement is necessary before PDT. In here, we designed a study to answer that question. Methods: Patients were divided in two groups: In one of the groups (n = 17), debridement was performed before PDT and in the other (n = 40) only PDT treatment was performed. PDT sessions were performed once a week in all patients until healing was achieved, as indicated by visual inspection as well as by radiographic and laboratory exams. At the start of the study, the two groups had no statistical differences concerning their clinical features: average age, gender, insulin use, diabetes mellitus onset time and previous amputations. Results: PDT was effective in the treatment of 100% of the patients showing no relapses after one year of follow up. The group submitted to PDT without previous debridement had a statistically significant (p = 0.036, Mann-Whitney) shorter cure time (29 days, similar to 27%). Conclusion: Our data indicates that debridement is not necessary in the treatment of diabetic foot in patients that have enough peripheral arterial perfusion. In addition, we reproduced previous studies confirming that PDT is an efficient, safe, simple and affordable treatment method for the diabetic foot.Fundacao de Amparo a Pesquisa do Estado de Sao PauloCNPqHosp Anchieta, Fac Med ABC, Sao Bernardo Do Campo, BrazilFac Med ABC, Dept Bioquim, Santo Andre, BrazilUniv Sao Paulo, Dept Bioquim, Sao Paulo, BrazilUniv Fed Sao Paulo, Dept Med, Sao Paulo, BrazilUniv Fed Sao Paulo, Dept Med, Sao Paulo, BrazilFAPESP: 12/50680-5FAPESP: 13/07937-8Web of Scienc

Scale-Free model for governing universe dynamics

We investigate the effects of scale-free model on cosmology, providing, in this way, a statistical background in the framework of general relativity. In order to discuss properties and time evolution of some relevant universe dynamical parameters (cosmographic parameters), such as $H(t)$ (Hubble parameter), $q(t)$ (deceleration parameter), $j(t)$ (jerk parameter) and $s(t)$ (snap parameter), which are well re-defined in the framework of scale-free model, we analyze a comparison between WMAP data. Hence the basic purpose of the work is to consider this statistical interpretation of mass distribution of universe, in order to have a mass density $\rho$ dynamics, not inferred from Friedmann equations, via scale factor $a(t)$. This model, indeed, has been used also to explain a possible origin and a viable explanation of cosmological constant, which assumes a statistical interpretation without the presence of extended theories of gravity; hence the problem of dark energy could be revisited in the context of a classical probability distribution of mass, which is, in particular, for the scale-free model, $P(k)\sim k^{-\gamma}$, with $2<\gamma<3$. The $\Lambda$CDM model becomes, with these considerations, a consequence of the particular statistics together with the use of general relativity.Comment: 7 pages, 4 figure

Vitamin d deficiency induces chronic pain and microglial phenotypic changes in mice

The bioactive form of vitamin .D, 1,25‐dihydroxyvitamin D (1,25D3), exerts immunomodulatory actions resulting in neuroprotective effects potentially useful against neurodegenerative and autoimmune diseases. In fact, vitamin D deficiency status has been correlated with painful manifestations associated with different pathological conditions. In this study, we have investigated the effects of vitamin D deficiency on microglia cells, as they represent the main immune cells responsible for early defense at central nervous system (CNS), including chronic pain states. For this purpose, we have employed a model of low vitamin D intake during gestation to evaluate possible changes in primary microglia cells obtained from postnatal day(P)2‐ 3 pups. Afterwards, pain measurement and microglia morphological analysis in the spinal cord level and in brain regions involved in the integration of pain perception were performed in the parents subjected to vitamin D restriction. In cultured microglia, we detected a reactive—activated and proliferative—phenotype associated with intracellular reactive oxygen species (ROS) generation. Oxidative stress was closely correlated with the extent of DNA damage and increased β‐galactosidase (B‐gal) activity. Interestingly, the incubation with 25D3 or 1,25D3 or palmitoylethanolamide, an endogenous ligand of peroxisome proliferator‐activated‐receptor‐alpha (PPAR‐α), reduced most of these effects. Morphological analysis of ex‐vivo microglia obtained from vitamin‐D‐deficient adult mice revealed an increased number of activated microglia in the spinal cord, while in the brain microglia appeared in a dystrophic phenotype. Remarkably, activated (spinal) or dystrophic (brain) microglia were detected in a prominent manner in females. Our data indicate that vitamin D deficiency produces profound modifications in microglia, suggesting a possible role of these cells in the sensorial dysfunctions associated with hypovitaminosis D

Volcanic spreading of Vesuvius, a new paradigm for interpreting its volcanic activity

We integrate geologic, structural, leveling and Differential SAR Interferometry data to show that Vesuvius began to spread onto its sedimentary substratum about 3,600 years ago. Moreover, we model the detected deformation with a solution of the lubrication approximation of the Navier-Stokes equations to show that spreading may continue for about 7,200 years more. Correlation of volcanic spreading with phases of the eruptive activity suggests that Plinian eruptions, which are thought to pose the major hazard, are less likely to occur in the near future.Published1-4partially_ope

Neuroinflammation, Mast Cells, and Glia: Dangerous Liaisons

The perspective of neuroinflammation as an epiphenomenon following neuron damage is being replaced by the awareness of glia and their importance in neural functions and disorders. Systemic inflammation generates signals that communicate with the brain and leads to changes in metabolism and behavior, with microglia assuming a pro-inflammatory phenotype. Identification of potential peripheral-to-central cellular links is thus a critical step in designing effective therapeutics. Mast cells may fulfill such a role. These resident immune cells are found close to and within peripheral nerves and in brain parenchyma/meninges, where they exercise a key role in orchestrating the inflammatory process from initiation through chronic activation. Mast cells and glia engage in crosstalk that contributes to accelerate disease progression; such interactions become exaggerated with aging and increased cell sensitivity to stress. Emerging evidence for oligodendrocytes, independent of myelin and support of axonal integrity, points to their having strong immune functions, innate immune receptor expression, and production/response to chemokines and cytokines that modulate immune responses in the central nervous system while engaging in crosstalk with microglia and astrocytes. In this review, we summarize the findings related to our understanding of the biology and cellular signaling mechanisms of neuroinflammation, with emphasis on mast cell-glia interactions