A New Day for Youth: Creating Sustainable Quality in Out-of-School Time

Reviews research on best practices and examines the elements needed to create and sustain high-quality afterschool and summer programs. Recommends a framework for improving staff capacity and training, support structures and leadership, and activities

The explosion of supernova 2011fe in the frame of the core-degenerate scenario

We argue that the properties of the Type Ia supernova (SN Ia) SN 2011fe can be best explained within the frame of the core-degenerate (CD) scenario. In the CD scenario a white dwarf (WD) merges with the core of an asymptotic giant branch (AGB) star and forms a rapidly rotating WD, with a mass close to and above the critical mass for explosion. Rapid rotation prevents immediate collapse and/or explosion. Spinning down over a time of 0-10 Gyr brings the WD to explosion. A very long delayed explosion to post-crystallization phase, which lasts for about 2 Gyr leads to the formation of a highly carbon-enriched outer layer. This can account for the carbon-rich composition of the fastest-moving ejecta of SN 2011fe. In reaching the conclusion that the CD scenario best explains the observed properties of SN 2011fe we consider both its specific properties, like a very compact exploding object and carbon rich composition of the fastest-moving ejecta, and the general properties of SNe Ia.Comment: Accepted by MNRAS Letter

Toward a Systematic Evidence-Base for Science in Out-of-School Time: The Role of Assessment

Analyzes the tools used in assessments of afterschool and summer science programs, explores the need for comprehensive tools for comparisons across programs, and discusses the most effective structure and format for such a tool. Includes recommendations

Linking bacterial population dynamics and nutrient removal in the granular sludge biofilm ecosystem engineered for wastewater treatment

Intensive nutrient removal from wastewater in anaerobic-aerobic systems using granular sludge should rely on optimal balances at biofilm and microbial ecology levels. This study targets the impacts of reactor characteristics and fluctuations in operation conditions on nutrient removal and bacterial community structures by means of microbial and numerical ecology methods. The dynamics of both predominant and accompanying populations were investigated with high resolution on temporal and phylogenetic scales in two reactors operated during 5 months with synthetic wastewater. Multivariate analyses highlighted significant correlations from process to microbial scales in the first reactor, whereas nitrification and phosphorus removal might have been affected by oxygen mass transfer limitations with no impact at population level in the second system. The bacterial community continuum of the first reactor was composed of two major antagonistic Accumulibacter-Nitrosomonas-Nitrospira and Competibacter-Cytophaga-Intrasporangiaceae clusters that prevailed under conditions leading to efficient P- (> 95%) and N-removal (> 65%) and altered P- (< 90%) and N-removal (< 60%), respectively. A third cluster independent of performances was dominated by Xanthomonadaceae affiliates that were on average more abundant at 25 °C (31 ± 5%) than at 20 °C (22 ± 4%). Starting from the physiological traits of the numerous phylotypes identified, a conceptual model is proposed as a base for functional analysis in the granular sludge microbiome and for future investigations with complex real wastewate

On the Formation of Multiple-Shells Around Asymptotic Giant Branch Stars

Two types of models for the formation of semi-periodic concentric multiple shells (M-shells) around asymptotic giant branch (AGB) stars and in planetary nebulae are compared against observations. Models that attribute the M-shells to processes in an extended wind acceleration zone around AGB stars result in an optically thick acceleration zone, which reduces the acceleration efficiency in outer parts of the extended acceleration zone. This makes such models an unlikely explanation for the formation of M-shells. Models which attribute the M-shell to semi-periodic variation in one or more stellar properties are most compatible with observations. The only stellar variation models on time scales of 50-1500 years that have been suggested are based on an assumed solar-like magnetic cycle. Although ad-hoc, the magnetic cycle assumption fits naturally into the increasingly popular view that magnetic activity plays a role in shaping the wind from upper AGB stars.Comment: 8 pages, Submitted to Ap

DA Wand: Distortion-Aware Selection using Neural Mesh Parameterization

We present a neural technique for learning to select a local sub-region around a point which can be used for mesh parameterization. The motivation for our framework is driven by interactive workflows used for decaling, texturing, or painting on surfaces. Our key idea is to incorporate segmentation probabilities as weights of a classical parameterization method, implemented as a novel differentiable parameterization layer within a neural network framework. We train a segmentation network to select 3D regions that are parameterized into 2D and penalized by the resulting distortion, giving rise to segmentations which are distortion-aware. Following training, a user can use our system to interactively select a point on the mesh and obtain a large, meaningful region around the selection which induces a low-distortion parameterization. Our code and project page are currently available.Comment: Project page: https://threedle.github.io/DA-Wand/ Code: https://github.com/threedle/DA-Wan

The alignment of galaxy spin with the shear field in observations

Tidal torque theory suggests that galaxies gain angular momentum in the linear stage of structure formation. Such a theory predicts alignments between the spin of haloes and tidal shear field. However, non-linear evolution and angular momentum acquisition may alter this prediction significantly. In this paper, we use a reconstruction of the cosmic shear field from observed peculiar velocities combined with spin axes extracted from galaxies within $115\, \mathrm{Mpc}$ ($\sim8000 \, {\mathrm {km}}{\mathrm s}^{-1}$) from 2MRS catalog, to test whether or not galaxies appear aligned with principal axes of shear field. Although linear reconstructions of the tidal field have looked at similar issues, this is the first such study to examine galaxy alignments with velocity-shear field. Ellipticals in the 2MRS sample, show a statistically significant alignment with two of the principal axes of the shear field. In general, elliptical galaxies have their short axis aligned with the axis of greatest compression and perpendicular to the axis of slowest compression. Spiral galaxies show no signal. Such an alignment is significantly strengthened when considering only those galaxies that are used in velocity field reconstruction. When examining such a subsample, a weak alignment with the axis of greatest compression emerges for spiral galaxies as well. This result indicates that although velocity field reconstructions still rely on fairly noisy and sparse data, the underlying alignment with shear field is strong enough to be visible even when small numbers of galaxies are considered - especially if those galaxies are used as constraints in the reconstruction.Comment: 9 pages, 3 figures, accepted in MNRA