Influence of Rb/Cs cation-exchange on inorganic Sn halide perovskites: From chemical structure to physical properties

CsSnI3 is a potential lead-free inorganic perovskite for solar energy applications due to its nontoxicity and attractive optoelectronic properties. Despite these advantages, photovoltaic cells using CsSnI3 have not been successful to date, in part due to low stability. We demonstrate how gradual substitution of Rb for Cs influences the structural, thermodynamic, and electronic properties on the basis of first-principles density functional theory calculations. By examining the effect of the Rb:Cs ratio, we reveal a correlation between octahedral distortion and band gap, including spin–orbit coupling. We further highlight the cation-induced variation of the ionization potential (work function) and the importance of surface termination for tin-based halide perovskites for engineering high-performance solar cells

Is Criminology Moving Toward a Paradigm Shift?: Evidence from a Survey of the American Society of Criminology

Ideology forms and colors our attitudes and values in ways that lead to a tendency to accept or reject data according to how well or how poorly they cohere with that ideology. Previous research has suggested that the ideological divide in criminology is between criminologists who focus on strictly environmentalist theories that give short shrift to individual differences, and those who focus on individual differences and are favorably disposed to the biological sciences (Wright & Miller, 1998; Walsh & Ellis, 2004). The former tend to be radicals and liberals and the latter tend to be conservatives and moderates, although there is no one-to-one correspondence (Wright & Miller, 1998). The theoretical disarray in criminology occasioned by this tendency (among other things) has been noted by a number of scholars (Barak, 1998; Dantzker, 1998; Walsh, 2002). The present study repeats and extends these earlier studies with the goals of evaluating the relationship between ideology and favored theory in comparison with the earlier studies to ascertain if the grip of ideology is loosening, and of assessing the possibility of interdisciplinary integration

Atomistic origins of the phase transition mechanism in Ge2Sb2Te5

Combined static and molecular dynamics first-principles calculations are used to identify a direct structural link between the metastable crystalline and amorphous phases of Ge2Sb2Te5. We find that the phase transition is driven by the displacement of Ge atoms along the rocksalt [111] direction from the stable-octahedron to high-energy-unstable tetrahedron sites close to the intrinsic vacancy regions, which give rise to the formation of local 4-fold coordinated motifs. Our analyses suggest that the high figures of merit of Ge2Sb2Te5 are achieved from the optimal combination of intrinsic vacancies provided by Sb2Te3 and the instability of the tetrahedron sites provided by GeTe

An Innovative Approach for Community Engagement: Using an Audience Response System

Community-based participatory research methods allow for community engagement in the effort to reduce cancer health disparities. Community engagement involves health professionals becoming a part of the community in order to build trust, learn from the community and empower them to reduce disparities through their own initiatives and ideas. Audience Response Systems (ARS) are an innovative and engaging way to involve the community and obtain data for research purposes using keypads to report results via power point. The use of ARS within communities is very limited and serves to widen the disparity gap by not delivering new advances in medical knowledge and technology among all population groups. ARS was implemented at a community town hall event sponsored by a National Institute on Minority Health and Health Disparities Exploratory Center of Excellence, the Center for Equal Health. Participants appreciated being able to see how everyone else answered and felt included in the research process. ARS is beneficial because the community can answer truthfully and provides instant research results. Additionally, researchers can collect large amounts of data quickly, in a non-threatening way while tracking individual responses anonymously. Audience Response Systems proved to be an effective tool for successfully accomplishing community-based participatory research

Sleep Profiles of Elite Swimmers During Different Training Phases

This study aims to describe the sleeping patterns during different training phases in competitive swimmers. Twelve national- and international-level swimmers (3 females and 9 males) were monitored during 4 different phases, consisting of a preparation training phase, a taper phase, a competition phase, and a rest phase. Sleep parameters were assessed using wrist activity monitors and self-reported sleep diaries. There was a moderately higher (d = 0.70–1.00) sleep onset latency during the competition phase compared with taper, train, and rest phases. Trivial to small differences were observed for total sleep time between phases (d = 0.05–0.40). Sleep efficiency was moderately higher (d = 0.60–0.75) in the training and taper phases compared with competition and rest. Restfulness and fragmentation index (FI) were lowest in the rest with differences between phases being small (d = 0.43–0.51) for restfulness and small to moderate (d = 0.43–0.62) for FI. Time in and out of bed was very largely later (d = 1.96–2.34) in rest compared with the other phases. Total nap time was moderately lower in rest (d = 1.13–1.18) compared with the training and competition phases, whereas there was a small difference (d = 0.46) compared with taper. To conclude, while there were trivial to small differences in sleep quantity between phases, there are small to moderate differences in other sleep parameters. Specifically, sleep onset latency was higher during the competition phase. In addition, this study highlights the substantial between-individual variations in sleep responses during different training phases

Graphene-based Josephson junction single photon detector

We propose to use graphene-based Josephson junctions (gJjs) to detect single photons in a wide electromagnetic spectrum from visible to radio frequencies. Our approach takes advantage of the exceptionally low electronic heat capacity of monolayer graphene and its constricted thermal conductance to its phonon degrees of freedom. Such a system could provide high sensitivity photon detection required for research areas including quantum information processing and radio-astronomy. As an example, we present our device concepts for gJj single photon detectors in both the microwave and infrared regimes. The dark count rate and intrinsic quantum efficiency are computed based on parameters from a measured gJj, demonstrating feasibility within existing technologies.Comment: 11 pages, 6 figures, and 1 table in the main tex

The Relationship of a Systemic Student Support Intervention to Academic Achievement in Urban Catholic Schools

Much of the achievement gap between rich and poor students can be attributed to out-of-school factors, yet few schools have a comprehensive, coordinated system for addressing students’ nonacademic needs. Within a group of Catholic schools located in one city, this study examines academic achievement on the Stanford Achievement Test battery in mathematics, reading, and language among 2nd through 8th grade students participating in such an intervention, and compares the results with those of similar nonparticipating students in nearby cities. Using hierarchical longitudinal growth modeling and adjusting for demographic characteristics, this study found that students in intervention schools outperformed the comparison group on average in 6th grade mathematics. Intervention students also experienced significantly higher rates of growth in achievement than the comparison group in all three subjects. The results suggest that systemic service provision models have the potential to help urban Catholic schools meet their mission of educating the whole child and serving the poorest families. Keywords Catholic education, longitudinal growth analysis, achievement gap Le lien entre une intervention systémique de soutien aux élèves et la réussite scolaire dans les écoles catholiques en milieu urbain. Une bonne partie de l\u27écart entre les résultats obtenus par les élèves riches et les pauvres peut être attribuée à des facteurs extérieurs à l\u27école, pourtant peu d\u27écoles disposent d\u27un système complet et coordonné pour résoudre les besoins extrascolaires des élèves. Cette étude, qui porte sur un groupe d\u27écoles catholiques situées dans une seule ville, examine la réussite scolaire sut la batterie de tests de réussite de Stanford en mathématiques, lecture et langage parmi des élèves de la 11eà la 3eparticipant à cette intervention et compare les résultats avec ceux d\u27élèves similaires, dans des villes voisines qui n\u27y participaient pas. À l\u27aide d\u27une modélisation longitudinale de croissance, avec un ajustement pour les caractéristiques démographiques, cette étude a trouvé que les élèves des écoles où avait lieu l\u27intervention avaient de meilleurs résultats en moyenne que le groupe de comparaison en mathématiques de classe de 6e. Les élèves bénéficiant de l\u27intervention ont aussi eu des taux de croissance plus élevés que le groupe de comparaison dans les trois matières. Ce résultat indique que des modèles de service systémique fourni aux élèves peuvent potentiellement aider les écoles catholiques urbaines à remplir leur mission d\u27éducation intégrale de l\u27enfant et rendre service aux familles pauvres. Mots-clés : éducation catholique, analyse longitudinale de croissance, écart de réussite Relación entre una intervención sistémica de apoyo al estudiante y los logros académicos en escuelas católicas urbanas La mayor parte de la brecha en los logros entre estudiantes ricos y pobres puede atribuirse a factores extraescolares, sin embargo, pocas escuelas disponen de un sistema comprensivo coordinado que aborde las necesidades no académicas de los estudiantes. Tomando un grupo de escuelas católicas ubicadas en una misma ciudad, este estudio examina los logros académicos en las pruebas de aptitud de Stanford (SAT) en matemáticas, lectura y lengua de estudiantes entre segundo y octavo curso que participan en tales intervenciones; y compara los resultados a los de estudiantes no participantes, con perfiles similares, en ciudades cercanas. Al emplear modelos de crecimiento longitudinal jerárquico y al ajustarlos a las características demográficas, el presente estudio encontró que los estudiantes de escuelas con intervención superaron la media de los resultados del grupo de comparación en 6º curso de matemáticas. Los estudiantes con intervención también experimentaron significativamente mayores tasas de crecimiento que los del grupo de comparación en las tres materias. Los resultados sugieren que los modelos que proveen servicios sistémicos disponen del potencial para ayudar a que las escuelas católicas urbanas cumplan su misión de educar al niño en su totalidad y de servir a las familias pobres. Palabras clave educación católica, análisis de crecimiento longitudinal, brecha de logro

Engaged in Research/Achieving Balance: A Case Example of Teaching Research to Masters of Social Work Students

This article considers the use of participatory action research and Photovoice as a tool for engaging graduate level social work students in research education. Photovoice is an investigative tool that assists people in critically reflecting on the everyday social and political realities of their lives, enriching their understanding of their communities and the issues pertinent to them, while at the same time, giving them a voice from which to educate others on these issues. In the context of a group assignment, 26 social work students, enrolled in an introductory graduate research course, were asked to reflect upon the question, “What does balance look like for you in the MSW program?” Thirty-two photographs with captions were submitted and analyzed by class members for relevant themes. Balance was described as existing along a continuum from balanced to unbalanced and was comprised of four major themes: connection, nurturance, keeping perspective, and disengagement. Although this teaching strategy was not formally assessed, preliminary impressions are that students benefited from participating in the Photovoice activity

Gas-grain models for interstellar anion chemistry

Long-chain hydrocarbon anions CnH- (n=4, 6, 8) have recently been found to be abundant in a variety of interstellar clouds. In order to explain their large abundances in the denser (prestellar/protostellar) environments, new chemical models are constructed that include gas-grain interactions. Models including accretion of gas-phase species onto dust grains and cosmic-ray-induced desorption of atoms are able to reproduce the observed anion-to-neutral ratios, as well as the absolute abundances of anionic and neutral carbon chains, with a reasonable degree of accuracy. Due to their destructive effects, the depletion of oxygen atoms onto dust results in substantially greater polyyne and anion abundances in high-density gas (with n_{H_2} >~ 10^5 cm^{-3}). The large abundances of carbon-chain-bearing species observed in the envelopes of protostars such as L1527 can thus be explained without the need for warm carbon-chain chemistry. The C6H- anion-to-neutral ratio is found to be most sensitive to the atomic O and H abundances and the electron density. Therefore, as a core evolves, falling atomic abundances and rising electron densities are found to result in increasing anion-to-neutral ratios. Inclusion of cosmic-ray desorption of atoms in high-density models delays freeze-out, which results in a more temporally-stable anion-to-neutral ratio, in better agreement with observations. Our models include reactions between oxygen atoms and carbon-chain anions to produce carbon-chain-oxide species C6O, C7O, HC6O and HC7O, the abundances of which depend on the assumed branching ratios for associative electron detachment