The Effects of Running Gravitational Coupling On Rotating Black Holes

In this work we investigate the consequences of running gravitational coupling on the properties of rotating black holes. Apart from the changes induced in the space-time structure of such black holes, we also study the implications to Penrose process and geodetic precession. We are motivated by the functional form of gravitational coupling previously investigated in the context of infra-red limit of asymptotic safe gravity theory. In this approach, the involvement of a new parameter $\tilde{\xi}$ in this solution makes it different from Schwarzschild black hole. The Killing horizon, event horizon and singularity of the computed metric is then discussed. It is noticed that the ergosphere is increased as $\tilde{\xi}$ increases. Considering the black hole solution in equatorial plane, the geodesics of particles, both null and time like cases, are explored. The effective potential is computed and graphically analyzed for different values of parameter $\tilde{\xi}$. The energy extraction from black hole is investigated via Penrose process. For the same values of spin parameter, the numerical results suggest that the efficiency of Penrose process is greater in quantum corrected gravity than in Kerr Black Hole. At the end, a brief discussion on Lense-Thirring frequency is also done.Comment: 32 pages, 16 figures, to be published in EPJ

Influence of the COVID-19 pandemic on the incidence of tuberculosis and influenza

We examined whether the COVID-19 pandemic has affected the incidence of tuberculosis (TB) and influenza in Serbia, a Southeast European country with a low TB incidence rate and a mandatory BCG vaccination at birth. The first case of COVID-19 was registered on March 6, 2020. Despite the need for a sudden adaptation of the health care system, routines of mycobacterial laboratories have never stopped. In 2020, the number of newly diagnosed TB patients was significantly lower than expected (p = 0.04), but the number of patients with influenza increased when compared to 2019. Although many patients with influenza A H1N1 were observed before the beginning of the COVID-19 pandemic, the increment of cases could also be a consequence of cases of influenza with COVID-like symptoms detected thereafter. It may also be attributed to misclassification of clinical cases that were negative for SARS-CoV-2 and reported as influenza. Difficulties to seek medical attention because of the COVID-19 pandemic and possible underreporting are considered as reasons for the decline in the incidence rate of TB. On the other hand, individual and social measures to prevent the spread of SARS-CoV-2 such as wearing face masks, social distancing, lockdown, which were strictly applied to COVID-19 patients, health care staffs and most of the population, could have hindered TB infections more than the two viral diseases, which appear to be more contagious. The increased motivation of the population to protect their health during the COVID-19 pandemic provided an opportunity for their effective education. This is crucial in further combating TB as a preventable disease

Main memory in HPC: do we need more, or could we live with less?

An important aspect of High-Performance Computing (HPC) system design is the choice of main memory capacity. This choice becomes increasingly important now that 3D-stacked memories are entering the market. Compared with conventional Dual In-line Memory Modules (DIMMs), 3D memory chiplets provide better performance and energy efficiency but lower memory capacities. Therefore, the adoption of 3D-stacked memories in the HPC domain depends on whether we can find use cases that require much less memory than is available now. This study analyzes the memory capacity requirements of important HPC benchmarks and applications. We find that the High-Performance Conjugate Gradients (HPCG) benchmark could be an important success story for 3D-stacked memories in HPC, but High-Performance Linpack (HPL) is likely to be constrained by 3D memory capacity. The study also emphasizes that the analysis of memory footprints of production HPC applications is complex and that it requires an understanding of application scalability and target category, i.e., whether the users target capability or capacity computing. The results show that most of the HPC applications under study have per-core memory footprints in the range of hundreds of megabytes, but we also detect applications and use cases that require gigabytes per core. Overall, the study identifies the HPC applications and use cases with memory footprints that could be provided by 3D-stacked memory chiplets, making a first step toward adoption of this novel technology in the HPC domain.This work was supported by the Collaboration Agreement between Samsung Electronics Co., Ltd. and BSC, Spanish Government through Severo Ochoa programme (SEV-2015-0493), by the Spanish Ministry of Science and Technology through TIN2015-65316-P project and by the Generalitat de Catalunya (contracts 2014-SGR-1051 and 2014-SGR-1272). This work has also received funding from the European Union’s Horizon 2020 research and innovation programme under ExaNoDe project (grant agreement No 671578). Darko Zivanovic holds the Severo Ochoa grant (SVP-2014-068501) of the Ministry of Economy and Competitiveness of Spain. The authors thank Harald Servat from BSC and Vladimir Marjanovi´c from High Performance Computing Center Stuttgart for their technical support.Postprint (published version

Role of echocardiography in stress cardiomyopathy diagnosis after tracheal extubation

Stress cardiomyopathy or Takotsubo cardiomyopathy is a new syndrome and still insufficiently recognized among emergency patients, hospitalized patients. Many different physical and emotional stressors are triggers, but individual susceptibility to Takotsubo cardiomyopathy can not be predicted. Takotsubo cardiomyopathy in surgical and critical care population is a huge diagnostic challenge. Apart that these patients are treated in stressful environment and conditions. Postoperatively due to change of consciousness and inability to speak we can not rely on verbal symptoms to make differential diagnosis. Although essential sometimes they can not be submitted to coronary angiography to exclude obstructive coronary disease due many risk factors. So, then we follow clinical course, electrocardiographic, radiologic and echocardiographic dynamic changes, laboratory findings and consiliar opinion to make diagnosis. We represent a case of Takotsubo cardiomyopathy in a 59-years old postmenopausal Caucasian woman after tracheal extubation. She was submitted to surgery of intraabdominal collection evacuation in short general endotracheal anesthesia

Performance impact of a slower main memory: a case study of STT-MRAM in HPC

In high-performance computing (HPC), significant effort is invested in research and development of novel memory technologies. One of them is Spin Transfer Torque Magnetic Random Access Memory (STT-MRAM) --- byte-addressable, high-endurance non-volatile memory with slightly higher access time than DRAM. In this study, we conduct a preliminary assessment of HPC system performance impact with STT-MRAM main memory with recent industry estimations. Reliable timing parameters of STT-MRAM devices are unavailable, so we also perform a sensitivity analysis that correlates overall system slowdown trend with respect to average device latency. Our results demonstrate that the overall system performance of large HPC clusters is not particularly sensitive to main-memory latency. Therefore, STT-MRAM, as well as any other emerging non-volatile memories with comparable density and access time, can be a viable option for future HPC memory system design.This work was supported by the Collaboration Agreement between Samsung Electronics Co., Ltd. and BSC, Spanish Government through Programa Severo Ochoa (SEV-2015-0493), by the Spanish Ministry of Science and Technology through TIN2015-65316-P project and by the Generalitat de Catalunya (contracts 2014-SGR-1051 and 2014-SGR-1272). This work has also received funding from the European Union's Horizon 2020 research and innovation programme under ExaNoDe project (grant agreement No 671578).Peer ReviewedPostprint (author's final draft

Disulfiram moderately restores impaired hepatic redox status of rats subchronically exposed to cadmium

Examination of cadmium (Cd) toxicity and disulfiram (DSF) effect on liver was focused on oxidative stress (OS), bioelements status, morphological and functional changes. Male Wistar rats were intraperitoneally treated with 1mg CdCl2/kg BW/day; orally with 178.5 mg DSF/kg BW/day for 1, 3, 10 and 21 days; and co-exposed from 22nd to 42nd day. The co-exposure nearly restored previously suppressed total superoxide dismutase (SOD), catalase (CAT) and increased glutathione peroxidase (GPx) activities; increased previously reduced glutathione reductase (GR) and total glutathione-S-transferase (GST) activities; reduced previously increased superoxide anion radical (O-2(center dot-)) and malondialdehyde (MDA) levels; increased zinc (Zn) and iron (Fe), and decreased copper (Cu) (yet above control value), while magnesium (Mg) was not affected; and decreased serum alanine aminotransferases (ALT) levels. Histopathological examination showed signs of inflammation process as previously demonstrated by exposure to Cd. Overall, we ascertained partial liver redox status improvement, compared with the formerly Cd-induced impact

Radical Scavenging and Antimicrobial Properties of Polyphenol Rich Waste Wood Extracts

The main focus of this study is to assess radical scavenging and antimicrobial activities of the 11 wood extracts: oak (Quercus petraea (Matt.) Liebl., Q. robur L., and Q. cerris L.), mulberry (Morus alba L.), myrobalan plum (Prunus cerasifera Ehrh.), black locust (Robinia pseudoacacia L.), and wild cherry (Prunus avium L.). High-performance thin-layer chromatography (HPTLC) provided initial phenolic screening and revealed different chemical patterns among investigated wood extracts. To identify individual compounds with radical scavenging activity DPPH-HPTLC, assay was applied. Gallic acid, ferulic and/or caffeic acids were identified as the compounds with the highest contribution of total radical scavenging activity. Principal component analysis was applied on the data set obtained from HPTLC chromatogram to classify samples based on chemical fingerprints: Quercus spp. formed separate clusters from the other wood samples. The wood extracts were evaluated for their antimicrobial activity against eight representative human and opportunistic pathogens. The lowest minimum inhibitory concentration (MIC) was recorded against Staphylococcus aureus for black locust, cherry and mulberry wood extracts. This work provided simple, low-cost and high-throughput screening of phenolic compounds and assessments of the radical scavenging properties of selected individual metabolites from natural matrix that contributed to scavenge free radicals.publishedVersio