Flat rotation curves in Chern-Simons modified gravity

We investigate the spacetime of a slowly rotating black hole in the Chern-Simons modified gravity. The long range feature of frame-dragging effect under the Chern-Simon gravity well explains the flat rotation curves of galaxies which is a central evidence of dark matter. Our solution provides a different scenario of rotating space from Goedel's solution.Comment: 4 pages, Accepted for publication in Phys. Rev.

Clinical and biological profiles of prospective blood donors at the Yaoundé Central Hospital and the Yaoundé University Teaching Hospital: Profils cliniques et biologiques des futurs donneurs de sang à l'hôpital central de Yaoundé et au CHU de Yaoundé

Assessing the profiles of prospective donors could help develop strategies to improve blood safety in our context. This study aimed to evaluate the clinical and biological profiles of prospective Cameroonian blood donors. To attain this objective, we carried out a cross-sectional and analytical study on all prospective blood donors that presented at the Yaoundé Central Hospital (HCY) and Yaoundé University Teaching Hospital (YUTH) blood banks from January 2017 to May 2017. After obtaining participants’ consent, we collected information from them, examined them, and collected five-milliliter blood samples from each of them. These blood samples were used to test for HIV, HBV, HCV, and Syphilis. A total of 247 prospective donors were retained for the study. We found that group “O” was noted in 50.9% of the participants and 97% were Rhesus-positive. Of the four main transfusion transmissible infections (TTIs) screened, 57 participants tested positive for at least one; nine were tested positive for HIV, twenty-six for HBV, ten for HCV, and sixteen for Syphilis. Co-infection was noted in four of the participants with two of them testing positive for both HIV and HBV, one for both HIV and HCV, and one for both HCV and Syphilis. On univariate analysis, a significant association was found between lymph nodes measuring more than 2 cm and the presence of a TTI. The presence of lymph nodes measuring more than 2 cm was associated with the presence of a TTI. L'évaluation des profils des donneurs potentiels pourrait aider à développer des stratégies pour améliorer la sécurité du sang dans notre contexte. Cette étude visait à évaluer les profils cliniques et biologiques des candidats donneurs de sang camerounais. Pour atteindre cet objectif, nous avons mené une étude transversale et analytique sur tous les candidats donneurs de sang qui se sont présentés aux banques de sang du Centre Hospitalier Central de Yaoundé (HCY) et du CHU de Yaoundé (YUTH) de janvier 2017 à mai 2017. Après obtention des participants ' consentement, nous avons recueilli des informations auprès d'eux, les avons examinés et prélevé des échantillons de sang de cinq millilitres sur chacun d'eux. Ces échantillons de sang ont été utilisés pour tester le VIH, le VHB, le VHC et la syphilis. Au total, 247 donneurs potentiels ont été retenus pour l'étude. Nous avons constaté que le groupe « O » était noté chez 50,9 % des participants et 97 % étaient rhésus positifs. Sur les quatre principales infections transmissibles par transfusion (ITT) dépistées, 57 participants ont été testés positifs pour au moins une ; neuf ont été testés positifs pour le VIH, vingt-six pour le VHB, dix pour le VHC et seize pour la syphilis. Une co-infection a été notée chez quatre des participants, dont deux étaient positifs à la fois pour le VIH et le VHB, un pour le VIH et le VHC et un pour le VHC et la syphilis. En analyse univariée, une association significative a été retrouvée entre les ganglions mesurant plus de 2 cm et la présence d'un ITT. La présence de ganglions mesurant plus de 2 cm était associée à la présence d'un ITT

A prescription for the asteroseismic surface correction

In asteroseismology, the surface effect is a disparity between the observed and the modelled oscillation frequencies. It originates from improper modelling of the surface layers in stars with solar-like oscillations. Correcting the surface effect usually requires using functions with free parameters, which are conventionally fitted to the observed frequencies. On the basis that the correction should vary smoothly across the H--R diagram, we parameterize it as a simple function of three stellar surface properties: surface gravity, effective temperature, and metallicity. We determine this function by fitting stars ranging from main-sequence dwarfs to red-giant-branch stars. The absolute amount of the surface correction increases with surface gravity, but the ratio between it and $\nu_{\rm max}$ decreases. Applying the prescription has an advantage of eliminating unrealistic surface correction, which improves parameter estimations with stellar modelling. Using two open clusters, we found that adopting the prescription can help reduce the scatter of the model-derived ages for each star in the same cluster. For an application, we provide a new revision for the $\Delta\nu$ scaling relation, using our prescription to account for the surface effect in models. The values of the correction factor, $f_{\Delta\nu}$, are up to 2\% smaller than those determined without the surface effect considered, suggesting decreases of up to 4\% in asteroseismic scaling radii and up to 8\% in asteroseismic scaling masses. This revision brings the asteroseismic properties into agreement with those determined from eclipsing binaries. Finally, the new correction factor and the stellar models with the corrected frequencies are made publicly available.Comment: 11 pages, 9 figures. Submitted to MNRAS. All comments (including on refs) are welcom

Orbital textures and charge density waves in transition metal dichalcogenides

Low-dimensional electron systems, as realized naturally in graphene or created artificially at the interfaces of heterostructures, exhibit a variety of fascinating quantum phenomena with great prospects for future applications. Once electrons are confined to low dimensions, they also tend to spontaneously break the symmetry of the underlying nuclear lattice by forming so-called density waves; a state of matter that currently attracts enormous attention because of its relation to various unconventional electronic properties. In this study we reveal a remarkable and surprising feature of charge density waves (CDWs), namely their intimate relation to orbital order. For the prototypical material 1T-TaS2 we not only show that the CDW within the two-dimensional TaS2-layers involves previously unidentified orbital textures of great complexity. We also demonstrate that two metastable stackings of the orbitally ordered layers allow to manipulate salient features of the electronic structure. Indeed, these orbital effects enable to switch the properties of 1T-TaS2 nanostructures from metallic to semiconducting with technologically pertinent gaps of the order of 200 meV. This new type of orbitronics is especially relevant for the ongoing development of novel, miniaturized and ultra-fast devices based on layered transition metal dichalcogenides

Definition of the role of chromosome 9p21 in sporadic melanoma through genetic analysis of primary tumours and their metastases

Malignant melanoma (MM) is thought to arise by sequential accumulation of genetic alterations in normal melanocytes. Previous cytogenetic and molecular studies indicated the 9p21 as the chromosomal region involved in MM pathogenesis. In addition to the CDKN genes (p16/CDKN2A, p15/CDKN2B and p19ARF, frequently inactivated in familial MM), widely reported data suggested the presence within this region of other melanoma susceptibility gene(s). To clearly assess the role of the 9p21 region in sporadic melanoma, we evaluated the presence of microsatellite instability (MSI) and loss of heterozygosity (LOH) in primary tumours as well as in synchronous or asynchronous metastases obtained from the same MM patients, using 9 polymorphic markers from a 17-cM region at 9p21. LOH and MSI were found in 27 (41%) and 11 (17%), respectively, out of 66 primary tumours analysed. In corresponding 58 metastases, MSI was found at higher rate (22; 38%), whereas a quite identical pattern of allelic deletions with 27 (47%) LOH+ cases were observed. Although the CDKN locus was mostly affected by LOH, an additional region of common allelic deletion corresponding to marker D9S171 was also identified. No significant statistical correlation between any 9p21 genetic alteration (LOH, MSI or both) and clinicopathological parameters was observed. © 2000 Cancer Research Campaign http://www.bjcancer.co

baseline predictive factors for efficacy of anti pd1 used in first line in melanoma patients an italian melanoma intergroup study

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The K2-HERMES Survey: Age and Metallicity of the Thick Disc

Asteroseismology is a promising tool to study Galactic structure and evolution because it can probe the ages of stars. Earlier attempts comparing seismic data from the {\it Kepler} satellite with predictions from Galaxy models found that the models predicted more low-mass stars compared to the observed distribution of masses. It was unclear if the mismatch was due to inaccuracies in the Galactic models, or the unknown aspects of the selection function of the stars. Using new data from the K2 mission, which has a well-defined selection function, we find that an old metal-poor thick disc, as used in previous Galactic models, is incompatible with the asteroseismic information. We show that spectroscopic measurements of [Fe/H] and [$\alpha$/Fe] elemental abundances from the GALAH survey indicate a mean metallicity of $\log (Z/Z_{\odot})=-0.16$ for the thick disc. Here $Z$ is the effective solar-scaled metallicity, which is a function of [Fe/H] and [$\alpha$/Fe]. With the revised disc metallicities, for the first time, the theoretically predicted distribution of seismic masses show excellent agreement with the observed distribution of masses. This provides an indirect verification of the asteroseismic mass scaling relation is good to within five percent. Using an importance-sampling framework that takes the selection function into account, we fit a population synthesis model of the Galaxy to the observed seismic and spectroscopic data. Assuming the asteroseismic scaling relations are correct, we estimate the mean age of the thick disc to be about 10 Gyr, in agreement with the traditional idea of an old $\alpha$-enhanced thick disc.Comment: 21 pages, submitted to MNRA

The superconductor-insulator transition in 2D dirty boson systems

Universal properties of the zero temperature superconductor-insulator transition in two-dimensional amorphous films are studied by extensive Monte Carlo simulations of bosons in a disordered medium. We report results for both short-range and long-range Coulomb interactions for several different points in parameter space. In all cases we observe a transition from a superconducting phase to an insulating Bose glass phase. {}From finite-size scaling of our Monte Carlo data we determine the universal conductivity $\sigma^*$ and the critical exponents at the transition. The result $\sigma^* = (0.55 \pm 0.06) (2e)^2/h$ for bosons with long-range Coulomb interaction is roughly consistent with experiments reported so far. We also find $\sigma^* = (0.14 \pm 0.03) (2e)^2/h$ for bosons with short-range interactions.Comment: Revtex 3.0, 54 pages, 17 figures included, UBCTP-93-01

Identification of a founder BRCA2 mutation in Sardinia

Sardinian population can be instrumental in defining the molecular basis of cancer, using the identity-by-descent method. We selected seven Sardinian breast cancer families originating from the northern-central part of the island with multiple affected members in different generations. We genotyped 106 members of the seven families and 20 control nuclear families with markers flanking BRCA2 locus at 13q12–q13. The detection of a common haplotype shared by four out of seven families (60%) suggests the presence of a founder BRCA2 mutation. Direct sequencing of BRCA2 coding exons of patients carrying the shared haplotype, allowed the identification of a ‘frame-shift’ mutation at codon 2867 (8765delAG), causing a premature termination-codon. This mutation was found in breast cancer patients as well as one prostate and one bladder cancer patient with shared haplotype. We then investigated the frequency of 8765delAG in the Sardinian breast cancer population by analysing 270 paraffin-embedded normal tissue samples from breast cancer patients. Five patients (1.7%) were found to be positive for the 8765delAG mutation. Discovery of a founder mutation in Sardinia through the identity-by-descent method demonstrates that this approach can be applied successfully to find mutations either for breast cancer or for other types of tumours. © 2000 Cancer Research Campaig