Multiple Photonic Shells Around a Line Singularity

Line singularities including cosmic strings may be screened by photonic shells until they appear as a planar wall.Comment: 6 page

On parameters of the Levi-Civita solution

The Levi-Civita (LC) solution is matched to a cylindrical shell of an anisotropic fluid. The fluid satisfies the energy conditions when the mass parameter $\sigma$ is in the range $0 \le \sigma \le 1$. The mass per unit length of the shell is given explicitly in terms of $\sigma$, which has a finite maximum. The relevance of the results to the non-existence of horizons in the LC solution and to gauge cosmic strings is pointed out.Comment: Latex, no figure

Levi-Civita Solutions Coupled with Electromagnetic Fields

The local and global properties of the Levi-Civita (LC) solutions coupled with an electromagnetic field are studied and some limits to the vacuum LC solutions are given. By doing such limits, the physical and geometrical interpretations of the free parameters involved in the solutions are made clear. Sources for both the LC vacuum solutions and the LC solutions coupled with an electromagnetic field are studied, and in particular it is found that all the LC vacuum solutions with $\sigma \ge 0$ can be produced by cylindrically symmetric thin shells that satisfy all the energy conditions, weak, dominant, and strong. When the electromagnetic field is present, the situation changes dramatically. In the case of a purely magnetic field, all the solutions with $\sigma \ge 1/\sqrt{8}$ or $\sigma \le - 1/\sqrt{8}$ can be produced by physically acceptable cylindrical thin shells, while in the case of a purely electric field, no such shells are found for any value of $\sigma$.Comment: Typed in Revtex, including two figure

ABC 2 -SPH risk score for in-hospital mortality in COVID-19 patients: development, external validation and comparison with other available scores

Coronavirus SARS-CoV-2; COVID-19; 2019-nCoV; Hospitalitzacions; MortalitatCoronavirus SARS-CoV-2; COVID-19; 2019-nCoV; Hospitalizaciones; MortalidadCoronavirus SARS-CoV-2; COVID-19; 2019-nCoV; Hospitalizations; MortalityObjectives The majority of available scores to assess mortality risk of coronavirus disease 2019 (COVID-19) patients in the emergency department have high risk of bias. Therefore, this cohort aimed to develop and validate a score at hospital admission for predicting in-hospital mortality in COVID-19 patients and to compare this score with other existing ones. Methods Consecutive patients (≥ 18 years) with confirmed COVID-19 admitted to the participating hospitals were included. Logistic regression analysis was performed to develop a prediction model for in-hospital mortality, based on the 3978 patients admitted between March–July, 2020. The model was validated in the 1054 patients admitted during August–September, as well as in an external cohort of 474 Spanish patients. Results Median (25–75th percentile) age of the model-derivation cohort was 60 (48–72) years, and in-hospital mortality was 20.3%. The validation cohorts had similar age distribution and in-hospital mortality. Seven significant variables were included in the risk score: age, blood urea nitrogen, number of comorbidities, C-reactive protein, SpO 2 /FiO 2 ratio, platelet count, and heart rate. The model had high discriminatory value (AUROC 0.844, 95% CI 0.829–0.859), which was confirmed in the Brazilian (0.859 [95% CI 0.833–0.885]) and Spanish (0.894 [95% CI 0.870–0.919]) validation cohorts, and displayed better discrimination ability than other existing scores. It is implemented in a freely available online risk calculator (https://abc2sph.com/). Conclusions An easy-to-use rapid scoring system based on characteristics of COVID-19 patients commonly available at hospital presentation was designed and validated for early stratification of in-hospital mortality risk of patients with COVID-19.This study was supported in part by Minas Gerais State Agency for Research and Development ( Fundação de Amparo à Pesquisa do Estado de Minas Gerais – FAPEMIG ) [grant number APQ-00208-20], National Institute of Science and Technology for Health Technology Assessment ( Instituto de Avaliação de Tecnologias em Saúde – IATS )/ National Council for Scientific and Technological Development ( Conselho Nacional de Desenvolvimento Científico e Tecnológico – CNPq ) [grant number 465518/2014-1], and CAPES Foundation ( Coordenação de Aperfeiçoamento de Pessoal de Nível Superior ) [grant number 88887.507149/2020-00]. AS was supported by a postdoctoral grant “Juan Rodés” (JE18/00022) from Instituto de Salud Carlos III through the Ministry of Economy and Competitiveness, Spain

The Deformable Universe

The concept of smooth deformations of a Riemannian manifolds, recently evidenced by the solution of the Poincar\'e conjecture, is applied to Einstein's gravitational theory and in particular to the standard FLRW cosmology. We present a brief review of the deformation of Riemannian geometry, showing how such deformations can be derived from the Einstein-Hilbert dynamical principle. We show that such deformations of space-times of general relativity produce observable effects that can be measured by four-dimensional observers. In the case of the FLRW cosmology, one such observable effect is shown to be consistent with the accelerated expansion of the universe.Comment: 20 pages, LaTeX, 3 figure

Plasmodium Infection Promotes Genomic Instability and AID-Dependent B Cell Lymphoma

SummaryChronic infection with Plasmodium falciparum was epidemiologically associated with endemic Burkitt’s lymphoma, a mature B cell cancer characterized by chromosome translocation between the c-myc oncogene and Igh, over 50 years ago. Whether infection promotes B cell lymphoma, and if so by which mechanism, remains unknown. To investigate the relationship between parasitic disease and lymphomagenesis, we used Plasmodium chabaudi (Pc) to produce chronic malaria infection in mice. Pc induces prolonged expansion of germinal centers (GCs), unique compartments in which B cells undergo rapid clonal expansion and express activation-induced cytidine deaminase (AID), a DNA mutator. GC B cells elicited during Pc infection suffer widespread DNA damage, leading to chromosome translocations. Although infection does not change the overall rate, it modifies lymphomagenesis to favor mature B cell lymphomas that are AID dependent and show chromosome translocations. Thus, malaria infection favors mature B cell cancers by eliciting protracted AID expression in GC B cells.PaperCli

A total transcriptome profiling method for plasma-derived extracellular vesicles: applications for liquid biopsies

Extracellular vesicles (EVs) are key mediators of intercellular communication. Part of their biological effects can be attributed to the transfer of cargos of diverse types of RNAs, which are promising diagnostic and prognostic biomarkers. EVs found in human biofluids are a valuable source for the development of minimally invasive assays. However, the total transcriptional landscape of EVs is still largely unknown. Here we develop a new method for total transcriptome profiling of plasma-derived EVs by next generation sequencing (NGS) from limited quantities of patient-derived clinical samples, which enables the unbiased characterization of the complete RNA cargo, including both small- and long-RNAs, in a single library preparation step. This approach was applied to RNA extracted from EVs isolated by ultracentrifugation from the plasma of five healthy volunteers. Among the most abundant RNAs identified we found small RNAs such as tRNAs, miRNAs and miscellaneous RNAs, which have largely unknown functions. We also identified protein-coding and long noncoding transcripts, as well as circular RNA species that were also experimentally validated. This method enables, for the first time, the full spectrum of transcriptome data to be obtained from minute patient-derived samples, and will therefore potentially allow the identification of cell-to-cell communication mechanisms and biomarkers.Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP)Gillson-Longenbaugh FoundationNational Institutes of Health (NIH/NCATS) through the NIH Common Fund, Office of Strategic Coordination (OSC)AC Camargo Canc Ctr, Lab Med Genom, Sao Paulo, SP, BrazilAC Camargo Canc Ctr, Lab Computat Biol, Sao Paulo, SP, BrazilUniv Sao Paulo, Inst Biomed Sci, Dept Cell & Dev Biol, Sao Paulo, SP, BrazilUniv Fed Sao Paulo, Electron Microscopy Ctr, Sao Paulo, SP, BrazilUniv Texas MD Anderson Canc Ctr, Dept Expt Therapeut, Houston, TX 77030 USAUniv Texas MD Anderson Canc Ctr, Ctr RNA Interference & Non Coding RNAs, Houston, TX 77030 USAUniv New Mexico, Comprehens Canc Ctr, Albuquerque, NM 87131 USAUniv New Mexico, Sch Med, Div Hematol Oncol, Dept Internal Med, Albuquerque, NM 87131 USAUniv New Mexico, Sch Med, Div Mol Med, Dept Internal Med, Albuquerque, NM 87131 USARockefeller Univ, Lab Mol Immunol, 1230 York Ave, New York, NY 10021 USAFMUSP, Lab Neurociencias Alzira Denise Hertzog Silva LIM, Inst Psiquiatria, Sao Paulo, SP, BrazilUniv Fed Sao Paulo, Electron Microscopy Ctr, Sao Paulo, SP, BrazilFAPESP: 2011/09172-3FAPESP: 2014/26897-0Web of Scienc

Brane-World charges

As opposed to usual Einstein gravity in four dimensions, the Brane-World scenario allows the construction of a local density of gravitational energy (and also of momentum, of angular momentum, etc...). This is a direct consequence of the hypothesis that our universe is located at the boundary of a five-dimensional diffeomorphism invariant manifold. We compute these Brane-World densities of charge using the Lanczos-Israel boundary conditions. To proceed, we implement an explicitely covariant generalization of the Hamiltonian procedure of Regge and Teitelboim given in a previous work. We finally study two simple Brane-World examples.Comment: 22 pages, LaTex. Minor errors corrected and references added. Final version to appear in Class. Qu. Gra

Stellar populations in NGC 5128 with the VLT: evidence for recent star formation

We resolve stars of the nearest giant elliptical galaxy NGC 5128 using VLT with FORS1 and ISAAC. We construct deep U, V and Ks color-magnitude and color-color diagrams in two different halo fields (in the halo and in the north-eastern diffuse shell). In the outer, shell field, at ~14 kpc from the center of the galaxy, there is a significant recent star formation with stars as young as 10 Myr, approximately aligned with the prominent radio and x-ray jet from the nucleus of the host AGN. Ionized gas filaments are evident in ultraviolet images near the area where neutral HI and CO molecular gas was previously observed. The underlying stellar population of the halo of the giant elliptical is predominantly old with a very broad metallicity distribution. The presence of an extended giant branch reaching M_bol=-5 mag suggests the existence of a significant intermediate-age AGB population in the halo of this galaxy.Comment: 18 pages, 18 figures; to be published in A&A; high res. version at http://www.eso.org/~mrejkuba/cenA_starsVLT.p

UVES/VLT high resolution spectroscopy of GRB 050730 afterglow: probing the features of the GRB environment

We analyze high resolution spectroscopic observations of the optical afterglow of GRB050730, obtained with UVES@VLT about hours after the GRB trigger. The spectrum shows that the ISM of the GRB host galaxy at z = 3.967 is complex, with at least five components contributing to the main absorption system. We detect strong CII*, SiII*, OI* and FeII* fine structure absorption lines associated to the second and third component. For the first three components we derive information on the relative distance from the site of the GRB explosion. Component 1, which has the highest redshift, does not present any fine structure nor low ionization lines; it only shows very high ionization features, such as CIV and OVI, suggesting that this component is very close to the GRB site. From the analysis of low and high ionization lines and fine structure lines, we find evidences that the distance of component 2 from the site of the GRB explosion is 10-100 times smaller than that of component 3. We evaluated the mean metallicity of the z=3.967 system obtaining values about 0.01 of the solar metallicity or less. However, this should not be taken as representative of the circumburst medium, since the main contribution to the hydrogen column density comes from the outer regions of the galaxy while that of the other elements presumably comes from the ISM closer to the GRB site. Furthermore, difficulties in evaluating dust depletion correction can modify significantly these values. The mean [C/Fe] ratio agrees well with that expected by single star-formation event models. Interestingly the [C/Fe] of component 2 is smaller than that of component 3, in agreement with GRB dust destruction scenarios, if component 2 is closer than component 3 to the GRB site.Comment: 11 pages, 15 postscript figures, accepted for pubblication in A&