Early shear bond strength of experimental amalgam-bonding combinations with and without thermocycling

Le but de cette étude était d’évaluer la résistance au cisaillement de l’amalgame collé à la dentine en utilisant quatre systèmes de collage différents. Quatre-vingt dents de sagesse humaines extraites, d’environ la même taille, ont été sélectionnées. Les dents ont été sectionnées parallèlement au plan occlusal à mihauteur coronaire pour exposer la dentine, puis la moitié de chaque dent a été incluse dans de la résine acrylique. Quatre systèmes de collage ont été utilisés selon les recommandations des fabricants. Les surfaces de l’émail et de la dentine des dents en cours de restauration avec un amalgame collé ont été mordancées, rincées, recouvertes d’une couche de primer/adhésif, restaurées avec du Valiant PhD-XT avec condensation pour entremêler l’amalgame à l’adhésif en cours de prise, photopolymérisées (30 sec) et conditionnées (l’eau distillée, 37°C, 24h). La moitié de tous les échantillons ont été thermocyclés pendant 24 heures (5°C/ 55°C, le temps de séjour: 1 minute, 500 cycles). La résistance au cisaillement a été testée pour tous les échantillons (taux de chargement=1mm/min, 25 °C). Les résultats (MPa=charge de rupture/zone de collage) pour les groupes (n=10) ont été statistiquement analysés (2-way ANOVA et Tukey-Kramer post hoc, p ≤ 0,05). La résistance au cisaillement des groupes thermocyclés était plus élevée (p \u3c 0,05). Les résultats pour les groupes 1-4 pour le stockage seulement (6,7 ± 1,6, 6,5 ± 1,0, 3,6 ± 0,9, 6,4 ± 2,5) par rapport aux groupes thermocyclés (13,3 ± 3,0, 15,1 ± 4,9, 15,4 ± 4,7, 18,2 ± 5,8) n’a montré pratiquement aucun effet du type de collage ainsi qu’aucune interaction du type de collage avec le thermocyclage. Le mode d’échec le plus commun était l’échec adhésif après thermocyclage

Evolutionary Origins of Binary Neutron Star Mergers: Effects of Common Envelope Efficiency and Metallicity

The formation histories of compact binary mergers, especially stellar-mass binary-black hole mergers, have recently come under increased scrutiny and revision. In this paper we revisit the question of the dominant formation channel and efficiency of forming binary neutron-star mergers. We use the stellar and binary evolution code MESA and implement an up-to-date and detailed method for common envelope and mass transfer. We preform simulations for donor masses between 8-20 solar masses with a neutron star companion of 1.4 and 2.0 solar masses, at two metallicities, using varying common envelope efficiencies, and two prescriptions for electron-capture supernovae. In contrast to the case of binary-black hole mergers, for a neutron star companion of 1.4 solar masses, all binary neutron star mergers are formed following a common envelope phase, while for a neutron star mass of 2.0 solar masses we identify a small subset of mergers following only stable mass transfer if the neutron star receives a large natal kick. Regardless of neutron star companion mass, we find that large supernova natal kicks are favored in the formation of binary neutron star mergers, and find more mergers at subsolar metallicity compared to solar.Comment: accepted to Ap

Novel roles for chloride channels, exchangers, and regulators in chronic inflammatory airway diseases

Chloride transport proteins play critical roles in inflammatory airway diseases, contributing to the detrimental aspects of mucus overproduction, mucus secretion, and airway constriction. However, they also play crucial roles in contributing to the innate immune properties of mucus and mucociliary clearance. In this review, we focus on the emerging novel roles for a chloride channel regulator (CLCA1), a calcium-activated chloride channel (TMEM16A), and two chloride exchangers (SLC26A4/pendrin and SLC26A9) in chronic inflammatory airway diseases

Localization of Compact Binary Sources with Second Generation Gravitational-wave Interferometer Networks

GW170817 began gravitational-wave multimessenger astronomy. However, GW170817 will not be representative of detections in the coming years -- typical gravitational-wave sources will be closer the detection horizon, have larger localization regions, and (when present) will have correspondingly weaker electromagnetic emission. In its design state, the gravitational-wave detector network in the mid-2020s will consist of up to five similar-sensitivity second-generation interferometers. The instantaneous sky-coverage by the full network is nearly isotropic, in contrast to the configuration during the first \change{three} observing runs. Along with the coverage of the sky, there are also commensurate increases in the average horizon for a given binary mass. We present a realistic set of localizations for binary neutron stars and neutron star--black hole binaries, incorporating intra-network duty cycles and selection effects on the astrophysical distributions. Based on the assumption of an $80\%$ duty cycle, and that two instruments observe a signal above the detection threshold, we anticipate a median of $28$ sq.\ deg.\ for binary neutron stars, and $50$--$120$ sq.\ deg.\ for neutron star--black hole (depending on the population assumed). These distributions have a wide spread, and the best localizations, even for networks with fewer instruments, will have localizations of $1$--$10$ sq.\ deg.\ range. The full five instrument network reduces localization regions to a few tens of degrees at worst.Comment: 20 pages, 8 figures, 3 tables, accepted in Ap

Deeper, Wider, Sharper: Next-Generation Ground-Based Gravitational-Wave Observations of Binary Black Holes

Next-generation observations will revolutionize our understanding of binary black holes and will detect new sources, such as intermediate-mass black holes. Primary science goals include: Discover binary black holes throughout the observable Universe; Reveal the fundamental properties of black holes; Uncover the seeds of supermassive black holes.Comment: 14 pages, 3 figures, White Paper Submitted to Astro2020 (2020 Astronomy and Astrophysics Decadal Survey) by GWIC 3G Science Case Team (GWIC: Gravitational Wave International Committee

All brain and still no body: Moving towards a pedagogy of embodiment in teacher education

We are four teacher educators who are interested in the role of emotions and embodiment in teacher education. The impetus for this study emerged after an embodied reflection workshop run by Rachel, Mandi, and Sharon at the 2014 SSTEP Castle Conference in which Monica participated. The workshop explored the ways in which teaching and learning to teach are emotional, cognitive, and embodied acts. After this experience we committed to a collaborative self-study, which we conducted between February and October, 2015, to track our attempts to use embodied pedagogies in our teacher education practices. In this study, we examine our efforts to enact embodied pedagogies in our practice and identify the challenges and benefits of doing so

The role of mass transfer and common envelope evolution in the formation of merging binary black holes

As the number of observed merging binary black holes (BHs) grows, accurate models are required to disentangle multiple formation channels. In models with isolated binaries, important uncertainties remain regarding the stability of mass transfer (MT) and common-envelope (CE) evolution. To study some of these uncertainties, we have computed simulations using MESA of a $30M_\odot$, low metallicity ($Z_\odot/10$) star with a BH companion. We developed a prescription to compute MT rates including possible outflows from outer Lagrangian points, and a method to self-consistently determine the core-envelope boundary in the case of CE evolution. We find that binaries survive a CE only if unstable MT happens after the formation of a deep convective envelope, resulting in a narrow range (0.2 dex) in period for envelope ejection. All cases where interaction is initiated with a radiative envelope have large binding energies ($\sim 10^{50}$ erg), and merge during CE even under the assumption that all the internal and recombination energy of the envelope, as well as the energy from an inspiral, is used for ejection. This is independent of core helium ignition for the donor, a condition under which various rapid-population synthesis calculations assume a successful ejection is possible. Moreover, we find that the critical mass ratio for instability is such that for periods between $\sim 1-1000$ days merging binary BHs can be formed via stable MT. A large fraction of these systems overflow their L$_2$ equipotential, in which case we find stable MT produces merging binary BHs even under extreme assumptions of mass and angular momentum outflows. Our conclusions are limited to the study of one donor star, but suggest that population synthesis calculations overestimate the formation rate of merging binary BHs produced by CE evolution, and that stable MT could dominate the rate from isolated binaries.Comment: 22 pages (including 4 pages of appendices). Abstract abridged for submission to the arXiv. Accepted for publication in Astronomy & Astrophysic