Earth Abundant Element Type I Clathrate Phases.

Earth abundant element clathrate phases are of interest for a number of applications ranging from photovoltaics to thermoelectrics. Silicon-containing type I clathrate is a framework structure with the stoichiometry A8-xSi46 (A = guest atom such as alkali metal) that can be tuned by alloying and doping with other elements. The type I clathrate framework can be described as being composed of two types of polyhedral cages made up of tetrahedrally coordinated Si: pentagonal dodecahedra with 20 atoms and tetrakaidecahedra with 24 atoms in the ratio of 2:6. The cation sites, A, are found in the center of each polyhedral cage. This review focuses on the newest discoveries in the group 13-silicon type I clathrate family: A₈E₈Si38 (A = alkali metal; E = Al, Ga) and their properties. Possible approaches to new phases based on earth abundant elements and their potential applications will be discussed

The Effect of Varied Gender Groupings on Argumentation Skills among Middle School Students in Different Cultures

The purpose of this mixed-methods study was to explore the effect of varied gender groupings on argumentation skills among middle school students in Taiwan and the United States in a project-based learning environment that incorporated a graph-oriented computer-assisted application (GOCAA). A total of 43 students comprised the treatment condition and were engaged in the collaborative argumentation process in same-gender groupings. Of these 43 students, 20 were located in the U.S. and 23 were located in Taiwan. A total of 40 students comprised the control condition and were engaged in the collaborative argumentation process in mixed-gender groupings. Of these 40 students, 19 were in the U.S. and 21 were in Taiwan. In each country, verbal collaborative argumentation was recorded and the students’ post essays were collected. Among females in Taiwan, one-way analysis of variance (ANOVA) indicated that statistically a significant gender-grouping effect was evident on the total argumentation skills outcome, while MANOVA indicated no significant gender-grouping effect on the combined set of skill outcomes. Among females in the U.S., MANOVA indicated statistically significant gender-grouping effect on the combined set of argumentation skills outcomes Specifically, U.S. female students in mixed-gender groupings (the control condition) significantly outperformed female students in single-gender groupings (the treatment condition) in the counterargument and rebuttal skills. No significant group differences were observed among males. A qualitative analysis was conducted to examine how the graph-oriented computer-assisted application supported students’ development of argumentation skills in different gender groupings in both countries. In each country, all teams in both conditions demonstrated a similar pattern of collaborative argumentation with the exception of three female teams in the U.S. Female teams, male teams, (the treatment condition) and mixed-gender teams (the control condition) demonstrated metacognition regulation skills in different degrees and with different scaffolding

Individualism-collectivism and interpersonal memory guidance of attention

Recently it has been shown that the allocation of attention by a participant in a visual search task can be affected by memory items that have to be maintained by a co-actor, when similar tasks are jointly engaged by dyads (He, Lever, & Humphreys, 2011). In the present study we examined the contribution of individualism-collectivism to this ‘interpersonal memory guidance’ effect. Actors performed visual search while a preview image was either held by the critical participant, held by a co-actor or was irrelevant to either participant. Attention during search was attracted to stimuli that matched the contents of the co-actor’s memory. This interpersonal effect correlated with the collectivism scores, and was enhanced by priming with a collectivistic scenario. The dimensions of individualism, however, did not contribute to performance. These data suggest that collectivism, but not individualism, modulates interpersonal influences on memory and attention in joint action

Value-Flow-Based Demand-Driven Pointer Analysis for C and C++

IEEE We present SUPA, a value-flow-based demand-driven flow- and context-sensitive pointer analysis with strong updates for C and C++ programs. SUPA enables computing points-to information via value-flow refinement, in environments with small time and memory budgets. We formulate SUPA by solving a graph-reachability problem on an inter-procedural value-flow graph representing a program's def-use chains, which are pre-computed efficiently but over-approximately. To answer a client query (a request for a variable's points-to set), SUPA reasons about the flow of values along the pre-computed def-use chains sparsely (rather than across all program points), by performing only the work necessary for the query (rather than analyzing the whole program). In particular, strong updates are performed to filter out spurious def-use chains through value-flow refinement as long as the total budget is not exhausted

Inertial coalescence of droplets on a partially wetting substrate

We consider the growth rate of the height of the connecting bridge in rapid surface-tension-driven coalescence of two identical droplets attached on a partially wetting substrate. For a wide range of contact angle values, the height of the bridge grows with time following a power law with a universal exponent of 2/3, up to a threshold time, beyond which a 1/2 exponent results, that is known for coalescence of freely-suspended droplets. In a narrow range of contact angle values close to 90°, this threshold time rapidly vanishes and a 1/2 exponent results for a 90° contact angle. The argument is confirmed by three-dimensional numerical simulations based on a diffuse interface method with adaptive mesh refinement and a volume-of-fluid method

Post-Oligarchic Evolution of Protoplanetary Embryos and the Stability of Planetary Systems

We investigate the orbit-crossing time (T_c) of protoplanet systems both with and without a gas-disk background. The protoplanets are initially with equal masses and separation (EMS systems) scaled by their mutual Hill's radii. In a gas-free environment, we find log (T_c/yr) = A+B \log (k_0/2.3). Through a simple analytical approach, we demonstrate that the evolution of the velocity dispersion in an EMS system follows a random walk. The stochastic nature of random-walk diffusion leads to (i) an increasing average eccentricity ~ t^1/2, where t is the time; (ii) Rayleigh-distributed eccentricities (P(e,t)=e/\sigma^2 \exp(-e^2/(2\sigma^2)) of the protoplanets; (iii) a power-law dependence of T_c on planetary separation. As evidence for the chaotic diffusion, the observed eccentricities of known extra solar planets can be approximated by a Rayleigh distribution. We evaluate the isolation masses of the embryos, which determine the probability of gas giant formation, as a function of the dust and gas surface densities.Comment: 15 pages, 13 figures (2 color ones), accepted for publication in Ap

Multi-scale characterisation of the 3D microstructure of a thermally-shocked bulk metallic glass matrix composite

Bulk metallic glass matrix composites (BMGMCs) are a new class of metal alloys which have significantly increased ductility and impact toughness, resulting from the ductile crystalline phases distributed uniformly within the amorphous matrix. However, the 3D structures and their morphologies of such composite at nano and micrometre scale have never been reported before. We have used high density electric currents to thermally shock a Zr-Ti based BMGMC to different temperatures, and used X-ray microtomography, FIB-SEM nanotomography and neutron diffraction to reveal the morphologies, compositions, volume fractions and thermal stabilities of the nano and microstructures. Understanding of these is essential for optimizing the design of BMGMCs and developing viable manufacturing methods

Hard X-ray and UV Observations of the 2005 January 15 Two-ribbon Flare

In this paper, we present comprehensive analysis of a two-ribbon flare observed in UV 1600{\AA} by Transition Region and Coronal Explorer and in HXRs by Reuven Ramaty High Energy Solar Spectroscopic Imager. HXR (25-100 keV) imaging observations show two kernels of size (FWHM) 15?? moving along the two UV ribbons. We find the following results. (1) UV brightening is substantially enhanced wherever and whenever the compact HXR kernel is passing, and during the HXR transit across a certain region, the UV count light curve in that region is temporally correlated with the HXR total flux light curve. After the passage of the HXR kernel, the UV light curve exhibits smooth monotonical decay. (2)We measure the apparent motion speed of the HXR sources and UV ribbon fronts, and decompose the motion into parallel and perpendicular motions with respect to the magnetic polarity inversion line (PIL). It is found that HXR kernels and UV fronts exhibit similar apparent motion patterns and speeds. The parallel motion dominates during the rise of the HXR emission, and the perpendicular motion starts and dominates at the HXR peak, the apparent motion speed being 10-40 km s-1. (3) We also find that UV emission is characterized by a rapid rise correlated with HXRs, followed by a long decay on timescales of 15-30 minutes. The above analysis provides evidence that UV brightening is primarily caused by beam heating, which also produces thick-target HXR emission. The thermal origin of UV emission cannot be excluded, but would produce weaker heating by one order of magnitude. The extended UV ribbons in this event are most likely a result of sequential reconnection along the PIL, which produces individual flux tubes (post-flare loops), subsequent non-thermal energy release and heating in these flux tubes, and then the very long cooling time of the transition region at the feet of these flux tubes.Comment: 8 figure

Dynamically orienting your own face facilitates the automatic attraction of attention

We report two experiments showing that dynamically orienting our own face facilitates the automatic attraction of attention. We had participants complete a cueing task where they had to judge the orientation of a lateralized target cued by a central face that dynamically changed its orientation. Experiment 1 showed a reliable cueing effect from both self- and friend-faces at a long stimulus onset asynchrony (SOA), however, the self-faces exclusively generated a spatial cueing effect at a short SOA. In Experiment 2, event-related potential (ERP) data to the face cues showed larger amplitudes in the N1 component for self-faces relative to friend- and unfamiliar-faces. In contrast, the amplitude of the P3 component was reduced for self compared with friend- and unfamiliar-other cues. The size of the self-bias effect in N1 correlated with the strength of self-biases in P3. The results indicate that dynamic changes in the orientation of one’s own face can provide a strong ecological cue for attention, enhancing sensory responses (N1) and reducing any subsequent uncertainty (P3) in decision-making

Precise static happens-before analysis for detecting UAF order violations in android

© 2019 IEEE. Unlike Java, Android provides a rich set of APIs to support a hybrid concurrency system, which consists of both Java threads and an event queue mechanism for dispatching asynchronous events. In this model, concurrency errors often manifest themselves in the form of order violations. An order violation occurs when two events access the same shared object in an incorrect order, causing unexpected program behaviors (e.g., null pointer dereferences). This paper presents SARD, a static analysis tool for detecting both intra-and inter-thread use-after-free (UAF) order violations, when a pointer is dereferenced (used) after it no longer points to any valid object, through systematic modeling of Android's concurrency mechanism. We propose a new flow-and context-sensitive static happens-before (HB) analysis to reason about the interleavings between two events to effectively identify precise HB relations and eliminate spurious event interleavings. We have evaluated SARD by comparing with NADROID, a state-of-the-art static order violation detection tool for Android. SARD outperforms NADROID in terms of both precision (by reporting three times fewer false alarms than NADROID given the same set of apps used by NADROID) and efficiency (by running two orders of magnitude faster than NADROID)