The Mass Dependance of Satellite Quenching in Milky Way-like Halos

Using the Sloan Digital Sky Survey, we examine the quenching of satellite galaxies around isolated Milky Way-like hosts in the local Universe. We find that the efficiency of satellite quenching around isolated galaxies is low and roughly constant over two orders of magnitude in satellite stellar mass ($M_{*}$ = $10^{8.5}-10^{10.5} \, M_{\odot}$), with only $\sim~20\%$ of systems quenched as a result of environmental processes. While largely independent of satellite stellar mass, satellite quenching does exhibit clear dependence on the properties of the host. We show that satellites of passive hosts are substantially more likely to be quenched than those of star-forming hosts, and we present evidence that more massive halos quench their satellites more efficiently. These results extend trends seen previously in more massive host halos and for higher satellite masses. Taken together, it appears that galaxies with stellar masses larger than about $10^{8}~M_{\odot}$ are uniformly resistant to environmental quenching, with the relative harshness of the host environment likely serving as the primary driver of satellite quenching. At lower stellar masses ($< 10^{8}~M_{\odot}$), however, observations of the Local Group suggest that the vast majority of satellite galaxies are quenched, potentially pointing towards a characteristic satellite mass scale below which quenching efficiency increases dramatically.Comment: 14 pages, 8 figure

A Dichotomy in Satellite Quenching Around L* Galaxies

We examine the star formation properties of bright (~0.1 L*) satellites around isolated ~L* hosts in the local Universe using spectroscopically confirmed systems in the Sloan Digital Sky Survey DR7. Our selection method is carefully designed with the aid of N-body simulations to avoid groups and clusters. We find that satellites are significantly more likely to be quenched than a stellar mass-matched sample of isolated galaxies. Remarkably, this quenching occurs only for satellites of hosts that are themselves quenched: while star formation is unaffected in the satellites of star-forming hosts, satellites around quiescent hosts are more than twice as likely to be quenched than stellar-mass matched field samples. One implication of this is that whatever shuts down star formation in isolated, passive L* galaxies also plays at least an indirect role in quenching star formation in their bright satellites. The previously-reported tendency for "galactic conformity" in color/morphology may be a by-product of this host-specific quenching dichotomy. The S\'ersic indices of quenched satellites are statistically identical to those of field galaxies with the same specific star formation rates, suggesting that environmental and secular quenching give rise to the same morphological structure. By studying the distribution of pairwise velocities between the hosts and satellites, we find dynamical evidence that passive host galaxies reside in dark matter halos that are ~45% more massive than those of star-forming host galaxies of the same stellar mass. We emphasize that even around passive hosts, the mere fact that galaxies become satellites does not typically result in star formation quenching: we find that only ~30% of ~0.1 L* galaxies that fall in from the field are quenched around passive hosts, compared with ~0% around star forming hosts.Comment: 14 pages, 9 figure

‘Fixed-axis’ magnetic orientation by an amphibian: non-shoreward-directed compass orientation, misdirected homing or positioning a magnetite-based map detector in a consistent alignment relative to the magnetic field?

Experiments were carried out to investigate the earlier prediction that prolonged exposure to long-wavelength (>500 nm) light would eliminate homing orientation by male Eastern red-spotted newts Notophthalmus viridescens. As in previous experiments, controls held in outdoor tanks under natural lighting conditions and tested in a visually uniform indoor arena under full-spectrum light were homeward oriented. As predicted, however, newts held under long-wavelength light and tested under either full-spectrum or long-wavelength light (>500 nm) failed to show consistent homeward orientation. The newts also did not orient with respect to the shore directions in the outdoor tanks in which they were held prior to testing. Unexpectedly, however, the newts exhibited bimodal orientation along a more-or-less `fixed' north-northeast—south-southwest magnetic axis. The orientation exhibited by newts tested under full-spectrum light was indistinguishable from that of newts tested under long-wavelength light, although these two wavelength conditions have previously been shown to differentially affect both shoreward compass orientation and homing orientation. To investigate the possibility that the `fixed-axis' response of the newts was mediated by a magnetoreception mechanism involving single-domain particles of magnetite, natural remanent magnetism (NRM) was measured from a subset of the newts. The distribution of NRM alignments with respect to the head—body axis of the newts was indistinguishable from random. Furthermore, there was no consistent relationship between the NRM of individual newts and their directional response in the overall sample. However, under full-spectrum, but not long-wavelength, light, the alignment of the NRM when the newts reached the 20 cm radius criterion circle in the indoor testing arena (estimated by adding the NRM alignment measured from each newt to its magnetic bearing) was non-randomly distributed. These findings are consistent with the earlier suggestion that homing newts use the light-dependent magnetic compass to align a magnetite-based `map detector' when obtaining the precise measurements necessary to derive map information from the magnetic field. However, aligning the putative map detector does not explain the fixed-axis response of newts tested under long-wavelength light. Preliminary evidence suggests that, in the absence of reliable directional information from the magnetic compass (caused by the 90° rotation of the response of the magnetic compass under long-wavelength light), newts may resort to a systematic sampling strategy to identify alignment(s) of the map detector that yields reliable magnetic field measurements

ACTIVE SUPPRESSION AS A POSSIBLE MECHANISM OF TOLERANCE IN TETRAPARENTAL MICE

Previous work has indicated that tetraparental mice, chimeric since the eight-cell stage because of embryo fusion using histoincompatible strain combinations, possess autospecific immune cells and blocking antibodies. Although this phenomenon has been demonstrated in vitro, it may have relevance to the self-tolerance shown by these mice in vivo. The experiments described here indicate that spleen cells from tetraparental mice can block mixed lymphocyte reactions between the two parental cell types, but not between unrelated strains. Furthermore, this suppressive ability is not affected by an otherwise effective treatment of the tetraparental spleen cells with anti-θ antibody and complement. The in vitro experimental system elaborated here should help to characterize the cell type responsible for the suppression

An Exploratory Study of Suboxone (Buprenorphine/ Naloxone) Film Splitting: Cutting Methods, Content Uniformity, and Stability

Suboxone films are U.S. Food and Drug Administration approved to treat opioid dependence. While the package insert states that films should not be cut, physicians often prescribe film fractions for treatment and tapering. There is no data to support this practice, and this study was initiated to evaluate cutting methods, content uniformity, and stability of split films. Suboxone 8-mg buprenorphine/2-mg naloxone films were split using four methods: 1) ruler/razor cut, 2) scissor cut, 3) fold/rip, and 4) fold/scissor cut. United States Pharmacopeia Chapter \u3c905\u3e was used to evaluate the weight variation and content uniformity of split films. The stability of split films stored in polybags was evaluated over 7 days. A stability-indicating high-performance liquid chromatography method was used for content uniformity and stability evaluation. The weight variation results were acceptable for the half films from all four cutting methods, but this was not true for the quarter films. The method of ruler/razor cut was determined most favorable and used for the content uniformity test. Based on the high-performance liquid chromatography results, the half films from the ruler/razor cut method met the passing criteria of United States Pharmacopeia Chapter \u3c905\u3e with acceptance values of 9.8 to 10.4 for buprenorphine and 8.4 to 11.5 for naloxone (≤15 is considered passing). The stability results indicated that both actives retained \u3e97.7% of initial strength. Four cutting methods were found to be acceptable for splitting Suboxone films into half but not quarter fractions. The half films from the ruler/razor cut method also passed United States Pharmacopeia Chapter \u3c905\u3e content uniformity test. Both actives remained stable for 7 days when the half films were stored in polybags at room temperature

Le consentement à la recherche en pharmacogénomique

[À l'origine dans / Was originally part of : CRDP - Droit, biotechnologie et rapport au milieu]Cet article analyse les pratiques éthiques et légales en matière de consentement éclairé dans le domaine de la recherche en pharmacogénomique. Les auteurs y examinent la manière dont les politiques internationales, régionales et nationales répondent aux nouveaux enjeux éthiques suscités par la pharmacogénomique. Ils concluent que le cadre éthique servant à guider les chercheurs dans ce domaine est encore en développement et nécessite un approfondissement pour répondre aux enjeux soulevés par cette importante discipli

Consent in Pharmacogenomic research

[À l'origine dans / Was originally part of : CRDP - Droit, biotechnologie et rapport au milieu]This article analyzes the emerging ethical and legal requirements for informed consent in pharmacogenomic research. It reviews how policies at the international, regional and national levels have responded to the ethical challenges raised by this new research area. It concludes that the pharmacogenomic policy framework is still in its infancy and needs to be further developed to answer the challenges raised by this important discipline

Goldilocks and Journal Publication: Finding a Fit That\u27s Just Right

Getting your work published in journals in ways that will help to advance your scholarly record is a complex and multifaceted process. This article is written for early career researchers and graduate and postgraduate students, providing practical advice about what to consider when developing a research and publication profile and establishing yourself within a research community. It explains a range of criteria that are useful to consider when choosing the best journal “fit” for each publication and for your academic trajectory. We hope that considering the elements identified and explained in this article will help you to find a fit that is “just right” for each of your future publications

Inhibition by small-molecule ligands of formation of amyloid fibrils of an immunoglobulin light chain variable domain.

Overproduction of immunoglobulin light chains leads to systemic amyloidosis, a lethal disease characterized by the formation of amyloid fibrils in patients' tissues. Excess light chains are in equilibrium between dimers and less stable monomers which can undergo irreversible aggregation to the amyloid state. The dimers therefore must disassociate into monomers prior to forming amyloid fibrils. Here we identify ligands that inhibit amyloid formation by stabilizing the Mcg light chain variable domain dimer and shifting the equilibrium away from the amyloid-prone monomer