Challenges to Self-Acceleration in Modified Gravity from Gravitational Waves and Large-Scale Structure

With the advent of gravitational-wave astronomy marked by the aLIGO GW150914 and GW151226 observations, a measurement of the cosmological speed of gravity will likely soon be realized. We show that a confirmation of equality to the speed of light as indicated by indirect Galactic observations will have important consequences for a very large class of alternative explanations of the late-time accelerated expansion of our Universe. It will break the dark degeneracy of self-accelerated Horndeski scalar-tensor theories in the large-scale structure that currently limits a rigorous discrimination between acceleration from modified gravity and from a cosmological constant or dark energy. Signatures of a self-acceleration must then manifest in the linear, unscreened cosmological structure. We describe the minimal modification required for self-acceleration with standard gravitational-wave speed and show that its maximum likelihood yields a 3-sigma poorer fit to cosmological observations compared to a cosmological constant. Hence, equality between the speeds challenges the concept of cosmic acceleration from a genuine scalar-tensor modification of gravity.Comment: 5 pages; v2 updated with newer data; v3 extended titl

Surface Structure Determination of Black Phosphorus Using Photoelectron Diffraction

Atomic structure of single-crystalline black phosphorus was studied by high resolution synchrotron-based photoelectron diffraction (XPD). The results show that the topmost phosphorene layer in the black phosphorus is slightly displaced compared to the bulk structure and presents a small contraction in the direction perpendicular to the surface. Furthermore, the XPD results show the presence of a small buckling among the surface atoms, in agreement with previously reported scanning tunneling microscopy results. The contraction of the surface layer added to the presence of the buckling indicates an uniformity in the size of the sp3 bonds between P atoms at the surface

Sports nutrology and gut microbiota: a systematic review

Introduction: Many of the established positive health benefits of exercise have been documented by historic discoveries in the field of exercise physiology. Regular physical training associated with nutritional health has broad health benefits for the gut microbiota, acting positively on almost all organ systems of the body. Objective: It was to analyze the main metabolic pathways modulated by nutrients, gut microbiota, and physical exercise in muscle regeneration and sports performance. Methods: The present study followed a systematic review model (PRISMA). The literary search process was carried out from July to September 2022 and was developed based on Scopus, PubMed, Science Direct, Scielo, and Google Scholar, with scientific articles from 2004 to 2022. The low quality of evidence was attributed to case reports, editorials, and brief communications, according to the GRADE instrument. The risk of bias was analyzed according to the Cochrane instrument. Results and Conclusion: We found 132 studies that underwent eligibility analysis, and then 31 of the 52 total studies were selected for this systematic review. According to the GRADE instrument, most studies showed homogeneity in their results, with I2 =98.9% >50%. The Funnel Plot showed a symmetrical behavior, not suggesting a significant risk of bias in studies with a smaller sample size. A healthy gut microbiota and a positive interaction with the immune system, promoted by diligent nutrological care, can be crucial for the muscle-gut axis and can influence the maintenance of muscle mass and its functionality in athletes. However, dysbiosis resulting from a negative interaction with the immune system can influence muscle wasting disorders. These changes can promote systemic inflammation, with overproduction of the pro-inflammatory cytokines TNF-α, IL-1β, and IL-6. Future studies should clarify whether gut microbiota dysbiosis and nutrient depletion are pathophysiologically associated with muscle wasting disorders and whether exercise can positively influence this supposed gut-muscle axis

Fault Localization in Multi-Threaded C Programs using Bounded Model Checking (extended version)

Software debugging is a very time-consuming process, which is even worse for multi-threaded programs, due to the non-deterministic behavior of thread-scheduling algorithms. However, the debugging time may be greatly reduced, if automatic methods are used for localizing faults. In this study, a new method for fault localization, in multi-threaded C programs, is proposed. It transforms a multi-threaded program into a corresponding sequential one and then uses a fault-diagnosis method suitable for this type of program, in order to localize faults. The code transformation is implemented with rules and context switch information from counterexamples, which are typically generated by bounded model checkers. Experimental results show that the proposed method is effective, in such a way that sequential fault-localization methods can be extended to multi-threaded programs.Comment: extended version of paper published at SBESC'1