Cosmology in GSG

We describe what cosmology looks like in the context of the geometric theory of gravity (GSG) based on a single scalar field. There are two distinct classes of cosmological solutions. An interesting feature is the possibility of having a bounce without invoking exotic equations of state for the cosmic fluid. We also discuss cosmological perturbation and present the basis of structure formation by gravitational instability in the framework of the geometric scalar gravity.Comment: 12 pages, 5 figures, accepted for publication in Phys. Rev.

More about scalar gravity

We discuss a class of models for gravity based on a scalar field. The models include and generalize the old approach by Nordstr\"om which predated and in some way inspired General Relativity. The class include also a model that we have recently introduced and discussed in its cosmological aspects (GSG). We present here a complete characterisation of the Schwarschild geometry as a vacuum solution of GSG and sketch a discussion of the first Post-Newtonian approximation.Comment: 11 pages, 1 figure, accepted for publication in PR

Geometric scalar theory of gravity

We present a geometric scalar theory of gravity. Our proposal will be described using the "background field method" introduced by Gupta, Feynman and others as a field theory formulation of general relativity. We analyze previous criticisms against scalar gravity and show how the present proposal avoids these difficulties. This concerns not only the theoretical complaints but also those related to observations. In particular, we show that the widespread belief of the conjecture that the source of scalar gravity must be the trace of the energy-momentum tensor - which is one of the main difficulties to couple gravity with electromagnetic phenomenon in previous models - does not apply to our geometric scalar theory. Some consequences of the new scalar theory are explored.Comment: We did some modifications which do not change the content of the tex

Modelo Acústico Análogo ao Buraco Negro de Schwarzschild.

Ainda não há uma comprovação experimental que possa validar os resultados obtidos da termodinâmica de buracos negros. Isso porque a radiação emitida pelo buraco negro, prevista pela teoria, é praticamente impossível de ser detectada devido ao baixo valo de sua ordem de grandeza. Na busca por indícios que possam validar a existência dessa radiação, o estudo de modelos análogos a esses objetos tem crescido consideravelmente nas últimas décadas. Eles permitem a idealização de experimentos em laboratórios que seriam impossíveis de serem realizados nos sistemas gravitacionais. Um fluido em movimento pode agir sobre o som da mesma forma que os espaços-tempo curvos podem influenciar na trajetória da luz na relatividade geral. Com isso, pode-se descrever a propagação dessas ondas sonoras através de uma métrica efetiva, sob a qual elas seguirão geodésicas nulas. Esta dissertação faz uma revisão destes estudos concentrando-se em uma analogia acústica para um buraco negro de Schwarzschild, demonstrando suas vantagens e limitações quando aplicada para o estudo da teoria de Hawking

Geometric Scalar Gravity

We review the main properties of the recently proposed the Geometric Scalar Gravity (GSG), emphasizing its agreement with classical tests of the gravitational field in the solar system and the amplitude of the gravitational radiation

Electrospun nanofibrous poly (Lactic Acid)/Titanium dioxide nanocomposite membranes for cutaneous scar minimization

The animal study was reviewed and approved by 10/2015-CEUA/ICT/CJSC-UNESP.Poly (lactic acid) (PLA) has been increasingly used in cutaneous tissue engineering due to its low cost, ease of handling, biodegradability, and biocompatibility, as well as its ability to form composites. However, these polymers possess a structure with nanoporous that mimic the cellular environment. In this study, nanocomposites are prepared using PLA and titanium dioxide (TiO2) (10 and 35%—w/w) nanoparticles that also function as an active anti-scarring agent. The nanocomposites were prepared using an electrospinning technique. Three different solutions were prepared as follows: PLA, 10% PLA/TiO2, and 35% PLA/TiO2 (w/w%). Electrospun PLA and PLA/TiO2 nanocomposites were characterized morphologically, structurally, and chemically using electron scanning microscopy, transmission electron microscopy, goniometry, and X-ray diffraction. L929 fibroblast cells were used for in vitro tests. The cytotoxic effect was evaluated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays. Versicam (VCAN), biglicam (BIG), interleukin-6 (IL6), interleukin-10 (IL-10), and type-1 collagen (COL1A1) genes were evaluated by RT-qPCR. In vivo tests using Wistar rats were conducted for up to 15 days. Nanofibrous fibers were obtained for all groups that did not contain residual solvents. No cytotoxic effects were observed for up to 168 h. The genes expressed showed the highest values of versican and collagen-1 (p < 0.05) for PLA/TiO2 nanocomposite scaffolds when compared to the control group (cells). Histological images showed that PLA at 10 and 35% w/w led to a discrete inflammatory infiltration and expression of many newly formed vessels, indicating increased metabolic activity of this tissue. To summarize, this study supported the potential of PLA/TiO2 nanocomposites ability to reduce cutaneous scarring in scaffolds.This work was supported by the National Council for Scientificand Technological Development (CNPq, #303752/2017-3 and#404683/2018-5 to AL and #304133/2017-5 and #424163/2016-0 to FM). AZ acknowledges financial support of the FCT throughUID/CTM/00264/2019 and Investigator FCT Research contract(IF/00071/2015) and the project PTDC/CTM-TEX/28295/2017 financed by FCT, FEDER, and POCI

Different subcellular localisations of TRIM22 suggest species-specific function

The B30.2/SPRY domain is present in many proteins, including various members of the tripartite motif (TRIM) protein family such as TRIM5α, which mediates innate intracellular resistance to retroviruses in several primate species. This resistance is dependent on the integrity of the B30.2 domain that evolves rapidly in primates and exhibits species-specific anti-viral activity. TRIM22 is another positively selected TRIM gene. Particularly, the B30.2 domain shows rapid evolution in the primate lineage and recently published data indicate an anti-viral function of TRIM22. We show here that human and rhesus TRIM22 localise to different subcellular compartments and that this difference can be assigned to the positively selected B30.2 domain. Moreover, we could demonstrate that amino acid changes in two variable loops (VL1 and VL3) are responsible for the different subcellular localisations