29 research outputs found
Enhanced magnetocaloric effect in frustrated magnets
The magnetothermodynamics of strongly frustrated classical Heisenberg
antiferromagnets on kagome, garnet, and pyrochlore lattices is examined. The
field induced adiabatic temperature change (dT/dH)_S is significantly larger
for such systems compared to ordinary non-frustrated magnets and also exceeds
the cooling rate of an ideal paramagnet in a wide range of fields. An
enhancement of the magnetocaloric effect is related to presence of a
macroscopic number of soft modes in frustrated magnets below the saturation
field. Theoretical predictions are confirmed with extensive Monte Carlo
simulations.Comment: 7 page
Realistic mock observations of the sizes and stellar mass surface densities of massive galaxies in FIRE-2 zoom-in simulations
The galaxy sizeâstellar mass and central surface densityâstellar mass relationships are fundamental observational constraints on galaxy formation models. However, inferring the physical size of a galaxy from observed stellar emission is non-trivial due to various observational effects, such as the mass-to-light ratio variations that can be caused by non-uniform stellar ages, metallicities, and dust attenuation. Consequently, forward-modelling light-based sizes from simulations is desirable. In this work, we use the skirtâ dust radiative transfer code to generate synthetic observations of massive galaxies (â MââŒ1011Mâ at z = 2, hosted by haloes of mass MhaloâŒ1012.5Mââ ) from high-resolution cosmological zoom-in simulations that form part of the Feedback In Realistic Environments project. The simulations used in this paper include explicit stellar feedback but no active galactic nucleus (AGN) feedback. From each mock observation, we infer the effective radius (Re), as well as the stellar mass surface density within this radius and within 1kpc (ÎŁe and ÎŁ1, respectively). We first investigate how well the intrinsic half-mass radius and stellar mass surface density can be inferred from observables. The majority of predicted sizes and surface densities are within a factor of 2 of the intrinsic values. We then compare our predictions to the observed sizeâmass relationship and the ÎŁ1âMâ and ÎŁeâMâ relationships. At z âł 2, the simulated massive galaxies are in general agreement with observational scaling relations. At z âČ 2, they evolve to become too compact but still star forming, in the stellar mass and redshift regime where many of them should be quenched. Our results suggest that some additional source of feedback, such as AGN-driven outflows, is necessary in order to decrease the central densities of the simulated massive galaxies to bring them into agreement with observations at z âČ 2
PTP1B is an androgen receptor-regulated phosphatase that promotes the progression of prostate cancer
The androgen receptor (AR) signaling axis plays a key role in the pathogenesis of prostate cancer. In this study, we found that the protein tyrosine phosphatase PTP1B, a well-established regulator of metabolic signaling, was induced after androgen stimulation of AR-expressing prostate cancer cells. PTP1B induction by androgen occurred at the mRNA and protein levels to increase PTP1B activity. High-resolution chromosome mapping revealed AR recruitment to two response elements within the first intron of the PTP1B encoding gene PTPN1, correlating with an AR-mediated increase in RNA polymerase II recruitment to the PTPN1 transcriptional start site. We found that PTPN1 and AR genes were coamplified in metastatic tumors and that PTPN1 amplification was associated with a subset of high-risk primary tumors. Functionally, PTP1B depletion delayed the growth of androgen-dependent human prostate tumors and impaired androgen-induced cell migration and invasion in vitro. However, PTP1B was also required for optimal cell migration of androgen-independent cells. Collectively, our results established the AR as a transcriptional regulator of PTPN1 transcription and implicated PTP1B in a tumor-promoting role in prostate cancer. Our findings support the preclinical testing of PTP1B inhibitors for prostate cancer treatment. ©2012 AACR
Recommended from our members
Gas kinematics in FIRE simulated galaxies compared to spatially unresolved HI observations.
The shape of a galaxy's spatially unresolved, globally integrated 21-cm emission line depends on its internal gas kinematics: galaxies with rotationally supported gas discs produce double-horned profiles with steep wings, while galaxies with dispersion-supported gas produce Gaussian-like profiles with sloped wings. Using mock observations of simulated galaxies from the FIRE project, we show that one can therefore constrain a galaxy's gas kinematics from its unresolved 21-cm line profile. In particular, we find that the kurtosis of the 21-cm line increases with decreasing V/Ï and that this trend is robust across a wide range of masses, signal-to-noise ratios, and inclinations. We then quantify the shapes of 21-cm line profiles from a morphologically unbiased sample of ~2000 low-redshift, HI-detected galaxies with M star = 107-11 Mâ and compare to the simulated galaxies. At M star âł 1010 Mâ, both the observed and simulated galaxies produce double-horned profiles with low kurtosis and steep wings, consistent with rotationally supported discs. Both the observed and simulated line profiles become more Gaussian like (higher kurtosis and less-steep wings) at lower masses, indicating increased dispersion support. However, the simulated galaxies transition from rotational to dispersion support more strongly: at M star 108-10 M, most of the simulations produce more Gaussian-like profiles than typical observed galaxies with similar mass, indicating that gas in the low-mass simulated galaxies is, on average, overly dispersion supported. Most of the lower-mass-simulated galaxies also have somewhat lower gas fractions than the median of the observed population. The simulations nevertheless reproduce the observed line-width baryonic Tully-Fisher relation, which is insensitive to rotational versus dispersion support
Rhodococcus equi Parte 1: epidemiologia, manifestaçÔes clĂnicas, diagnĂłstico e tratamento Rhodococcus equi Part 1: epidemiology, clinical manifestations, diagnosis and treatment
A rodococose Ă© uma doença de distribuição mundial causada pelo Rhodococcus equi, responsĂĄvel por taxas elevadas de mortalidade e grandes perdas econĂŽmicas relacionadas Ă pneumonia grave em potros com menos de seis meses de idade. Essa revisĂŁo inclui a etiologia, epidemiologia e patogenia da doença com atenção especial Ă proteĂna de superfĂcie VapA, seu principal determinante de virulĂȘncia. As principais manifestaçÔes clĂnicas sĂŁo apresentadas, bem como os mĂ©todos diagnĂłsticos e as suas aplicaçÔes, incluindo as novas estratĂ©gias em desenvolvimento. Da mesma maneira, as medidas terapĂȘuticas mais utilizadas sĂŁo tambĂ©m discutidas, abordando principalmente o uso de antibiĂłticos capazes de penetrar nas formaçÔes abscedantes.<br>Rodococosis is a disease that has a worldwide distribution caused by Rhodococcus equi. In foals under six months high mortality and great econimic losses are related to this bacterial pneumonia. This review includes the ethiology, epidemiology and pathogenesis of the disease with focus on the role of VapA, a surface protein, as the major determinant of virulence. The clinical manifestations are reviewed and diagnostic methods and their applications are commented, including new strategies that are still being developed. Likewise, the most common clinical therapies are discussed specially those using antibiotics that are known to penetrate in abcesses