The Post-Merger Magnetized Evolution of White Dwarf Binaries: The Double-Degenerate Channel of Sub-Chandrasekhar Type Ia Supernovae and the Formation of Magnetized White Dwarfs

Type Ia supernovae (SNe Ia) play a crucial role as standardizable cosmological candles, though the nature of their progenitors is a subject of active investigation. Recent observational and theoretical work has pointed to merging white dwarf binaries, referred to as the double-degenerate channel, as the possible progenitor systems for some SNe Ia. Additionally, recent theoretical work suggests that mergers which fail to detonate may produce magnetized, rapidly-rotating white dwarfs. In this paper, we present the first multidimensional simulations of the post-merger evolution of white dwarf binaries to include the effect of the magnetic field. In these systems, the two white dwarfs complete a final merger on a dynamical timescale, and are tidally disrupted, producing a rapidly-rotating white dwarf merger surrounded by a hot corona and a thick, differentially-rotating disk. The disk is strongly susceptible to the magnetorotational instability (MRI), and we demonstrate that this leads to the rapid growth of an initially dynamically weak magnetic field in the disk, the spin-down of the white dwarf merger, and to the subsequent central ignition of the white dwarf merger. Additionally, these magnetized models exhibit new features not present in prior hydrodynamic studies of white dwarf mergers, including the development of MRI turbulence in the hot disk, magnetized outflows carrying a significant fraction of the disk mass, and the magnetization of the white dwarf merger to field strengths $\sim 2 \times 10^8$ G. We discuss the impact of our findings on the origins, circumstellar media, and observed properties of SNe Ia and magnetized white dwarfs.Comment: Accepted ApJ version published on 8/20/13, with significant additional text added discussing the nature of the magnetized outflows, and possible CSM observational features relevant to NaID detection

In models we trust: preregistration, large samples, and replication may not suffice

Despite discussions about the replicability of findings in psychological research, two issues have been largely ignored: selection mechanisms and model assumptions. Both topics address the same fundamental question: Does the chosen statistical analysis tool adequately model the data generation process? In this article, we address both issues and show, in a first step, that in the face of selective samples and contrary to common practice, the validity of inferences, even when based on experimental designs, can be claimed without further justification and adaptation of standard methods only in very specific situations. We then broaden our perspective to discuss consequences of violated assumptions in linear models in the context of psychological research in general and in generalized linear mixed models as used in item response theory. These types of misspecification are oftentimes ignored in the psychological research literature. It is emphasized that the above problems cannot be overcome by strategies such as preregistration, large samples, replications, or a ban on testing null hypotheses. To avoid biased conclusions, we briefly discuss tools such as model diagnostics, statistical methods to compensate for selectivity and semi- or non-parametric estimation. At a more fundamental level, however, a twofold strategy seems indispensable: (1) iterative, cumulative theory development based on statistical methods with theoretically justified assumptions, and (2) empirical research on variables that affect (self-) selection into the observed part of the sample and the use of this information to compensate for selectivity

Tests of species‐specific models reveal the importance of drought in postglacial range shifts of a Mediterranean‐climate tree: insights from integrative distributional, demographic and coalescent modelling and ABC model selection

Past climate change has caused shifts in species distributions and undoubtedly impacted patterns of genetic variation, but the biological processes mediating responses to climate change, and their genetic signatures, are often poorly understood. We test six species‐specific biologically informed hypotheses about such processes in canyon live oak (Quercus chrysolepis) from the California Floristic Province. These hypotheses encompass the potential roles of climatic niche, niche multidimensionality, physiological trade‐offs in functional traits, and local‐scale factors (microsites and local adaptation within ecoregions) in structuring genetic variation. Specifically, we use ecological niche models (ENMs) to construct temporally dynamic landscapes where the processes invoked by each hypothesis are reflected by differences in local habitat suitabilities. These landscapes are used to simulate expected patterns of genetic variation under each model and evaluate the fit of empirical data from 13 microsatellite loci genotyped in 226 individuals from across the species range. Using approximate Bayesian computation (ABC), we obtain very strong support for two statistically indistinguishable models: a trade‐off model in which growth rate and drought tolerance drive habitat suitability and genetic structure, and a model based on the climatic niche estimated from a generic ENM, in which the variables found to make the most important contribution to the ENM have strong conceptual links to drought stress. The two most probable models for explaining the patterns of genetic variation thus share a common component, highlighting the potential importance of seasonal drought in driving historical range shifts in a temperate tree from a Mediterranean climate where summer drought is common.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/134178/1/mec13804-sup-0001-Supinfo.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134178/2/mec13804.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134178/3/mec13804_am.pd

Low voltage plasma jet with piezoelectric generator : preliminary evaluation of decontamination capabilities

This paper deals with the proof of concept and the preliminary evaluation of decontamination performances obtained with a plasma jet generated by a piezoelectric transformer. This low voltage supply solution (<10V) is investigated as a plasma jet device, compact and safe solution for the decontamination of medical thermo-sensitive devices. The principle of the piezoelectric generator is presented, followed by the optical spectroscopy of the plasma jet, the protocol conditions for the bactericidal effect observations and finally the reduction rates obtained on Pseudomonas aeruginosa and Staphylococcus aureus bacteria strains with an argon plasma jet at atmospheric pressure about 2.5W electrical input power

Implementación de unidades de calidad en la formación del profesorado: entre armonización de las prácticas de evaluación y singularidad de los contextos

The objective of the European project “Ecalfor” is to analyze the conditions in which the evaluation practices of the quality of the training of basic education teachers are developed, in orderto implement quality units in higher education institutions. The problematization is related to the application margins that allow taking into account the singularities of the contexts in an approach that seeks to harmonize the practices in reference to the common protocol to the Higher Education Institutions (HEIs) of the European countries (4), Latin America (10) and the Caribbean (2) according to international standards. The hypothesis is based on the mandate of an internationalization of teacher training based on the implementation of a protocol that aims to evaluate the quality of training and its organization while producing a distinction between higher education institutions that would have the necessary resources and those that could not create efficient conditions for their application. Through a theoretical framework related to the quality of training and its forms of evaluation, we have adopted a comparative methodological approach that aims to question the variables associated with both the conditions of implementation of quality units based on sociological, historical, anthropological contexts and cultural than what can fall under public educational policies. Thanks to the administered questionnaires, we have collected data from people in charge of quality in HEIs (managers, directors, technical secretaries and technical specialists...). The results show convergences and divergences between HEIs and between countries that define so many conditions that limit the implementation of a policy for evaluating the quality of teacher training in basic schools at the level of higher education in Latin America and in the rest of the world. Caribbean. In the end, HEIs “must explicitly commit to developing a culture that recognizes the importance of quality and evaluation in their work” (ENQA, 2015) in order to establish a guarantee of the quality of teacher training and education qualifications.El objetivo del proyecto europeo “Ecalfor” es analizar las condiciones en las cuales se desarrollan las prácticas de evaluación de la calidad de la formación de los docentes de educación básica, paraimplementar unidades de calidad en las instituciones de educación superior. La problematización se relaciona con los márgenes de aplicación que permitan tomar en cuenta las singularidades de los contextos en un enfoque que busca armonizar las prácticas en referencia al protocolo común a las instituciones de Educación Superior (IES) de los países de Europa (4), América Latina (10) y el Caribe (2) de acuerdo con los estándares internacionales. La hipótesis parte del mandato de una internacionalización de la formación docente a partir de la implementación de un protocolo que tiene como objetivo evaluar la calidad de la formación y su organización al mismo tiempo que produce una distinción entre las instituciones de educación superior que tendrían recursos necesarios y las que no podrían crear condiciones eficientes para su aplicación. A través un marco teórico relacionado a la calidad de formación ysus formas de evaluación, hemos adoptado un enfoque metodológico de comparación que pretende cuestionar las variables asociadas tanto las condiciones de implementación de las unidades de calidad en función de los contextos sociológicos, históricos, antropológicos y culturales que lo que puede caer bajo las políticas educativas públicas. Gracias a los cuestionarios administrados, hemos recogido datos desde personas encargadas de la calidad en IES (responsables, directores, secretarias técnicas y técnicas especialistas…). Los resultados demuestran convergencias y divergencias entre IES y entre países que definen tantas condiciones que limites por la implementación de una política de evaluación de la calidad de la formación de los docentes de las escuelas básicas al nivel de la educación superior en América latina y en el Caribe. Al final, las IES “deben comprometerse explícitamente a desarrollar una cultura que reconozca la importancia de la calidad y la evaluación en su trabajo “(ENQA, 2015) para establecer una garantía de la calidad de la formación del profesorado y de los títulos de educación.

Conformational Flexibility in the Enterovirus RNA Replication Platform

A presumed RNA cloverleaf (5′CL), located at the 5′-most end of the noncoding region of the enterovirus genome, is the primary established site for initiation of genomic replication. Stem–loop B (SLB) and stem–loop D (SLD), the two largest stem–loops within the 5′CL, serve as recognition sites for protein interactions that are essential for replication. Here we present the solution structure of rhinovirus serotype 14 5′CL using a combination of nuclear magnetic resonance spectroscopy and small-angle X-ray scattering. In the absence of magnesium, the structure adopts an open, somewhat extended conformation. In the presence of magnesium, the structure compacts, bringing SLB and SLD into close contact, a geometry that creates an extensive accessible major groove surface, and permits interaction between the proteins that target each stem–loop

Strong in-plane anisotropy in the electronic structure of fixed-valence β\beta-LuAlB4_4

The origin of intrinsic quantum criticality in the heavy-fermion superconductor $\beta$-YbAlB$_4$ has been attributed to strong Yb valence fluctuations and its peculiar crystal structure. Here, we assess these contributions individually by studying the isostructural but fixed-valence compound $\beta$-LuAlB$_4$. Quantum oscillation measurements and DFT calculations reveal a Fermi surface markedly different from that of $\beta$-YbAlB$_4$, consistent with a `large' Fermi surface there. We also find an unexpected in-plane anisotropy of the electronic structure, in contrast to the isotropic Kondo hybridization in $\beta$-YbAlB$_4$.Comment: 6 pages, 4 figure

Posttranscriptional regulation of PARG mRNA by HuR facilitates DNA repair and resistance to PARP inhibitors

The majority of pancreatic ductal adenocarcinomas (PDAC) rely on the mRNA stability factor HuR (ELAV-L1) to drive cancer growth and progression. Here, we show that CRISPR-Cas9–mediated silencing of the HuR locus increases the relative sensitivity of PDAC cells to PARP inhibitors (PARPi). PDAC cells treated with PARPi stimulated translocation of HuR from the nucleus to the cytoplasm, specifically promoting stabilization of a new target, poly (ADP-ribose) glycohydrolase (PARG) mRNA, by binding a unique sequence embedded in its 30 untranslated region. HuR-dependent upregulation of PARG expression facilitated DNA repair via hydrolysis of polyADP-ribose on related repair proteins. Accordingly, strategies to inhibit HuR directly promoted DNA damage accumulation, inefficient PAR removal, and persistent PARP-1 residency on chromatin (PARP-1 trapping). Immunoprecipitation assays demonstrated that the PARP-1 protein binds and posttranslationally modifies HuR in PARPi-treated PDAC cells. In a mouse xenograft model of human PDAC, PARPi monotherapy combined with targeted silencing of HuR significantly reduced tumor growth compared with PARPi therapy alone. Our results highlight the HuR–PARG axis as an opportunity to enhance PARPi-based therapies. ©2017 AACR