Creating Safer Routes to School for Fairfield Court Elementary Students

The purpose of this plan is to conduct a Walkabout study for Fairfield Court Elementary School in Richmond, Virginia through the guidelines of the Safe Routes to School program. The plan seeks to address infrastructural and non-infrastructural issues relating to traffic, safety, and travel routes for students who walk and bike to the school. The plan first identifies these issues and then details recommendations for the school through goals, objectives, and action items. An implementation plan for the school and its community partners is also detailed

Vector in Partition extension: Analysis of clustering when genetics distance is weighted by covariates.

Partitioning of data into clusters is a widely popular method of gaining insight into the similarities and differences of groups. Amongst the most popular approaches are the K-means and K-prototype methods, however, they fail to consider potential joint effects and interactions of the variables. The Vector in Partition (VIP) algorithm fills this gap with a distance measure designed to partition genetic and epigenetic data; specifically gene expression (GE), DNA methylation (CPG), and single nucleotide polymorphisms (SNP). This work focuses on an extension to the VIP method by furthering incorporating K-means and K-prototype framework within the novel distance measure to incorporate covariate data. This extension allows for another layer of combining complex joint effects of genetic/epi-genetic data and other health-related data to dictate clustering. The results from simulated data showed high accuracy, sensitivity, and specificity of cluster assignments across varying criteria and outperformance of the original VIP method

ANOFTALMIJA: NENASLJEDNA DEFORMACIJA OČIJU KOD TILAPIJE Oreochromis mossambicus

Seven male Oreochromis mossambicus with anophthalmia were found in a hatchery population. The deformity was not observed in either the Fl or F2 generations; consequently, it was a non-heritable congenital deformity.U populaciji uzgajanih tilapija Oreochromis mossambicus nadeno je sedum mužjaka s izraženom očnom deformacijom anoftalmijom. Oni su upotrijebljeni u križanjima koja su proizvela 11 porodica F1 generacije, te porodicu F2 generacije s 42 ribe. Kako niti kod jednog potomka ova deformacija nije utvrđena, može se zaključiti da je anoftalmija nenasljedna kongenitalna deformacija

BLS Spotlight on Statistics: Differences in Parents’ Time Use Between the Summer and the School Year

Parents can face different constraints on their time during school vacations than during the school year. Although different schools follow different calendars, summer months are frequently a time when children are not in school. Using data from the American Time Use Survey, this Spotlight on Statistics looks at differences in time use between the summer and the school year among parents of school-age children

Warm Rain in Southern West Africa: A Case Study at Savè

International audienceA warm-rain episode over southern West Africa is analyzed using unprecedented X-band radar observations from Savè, Benin and a Large-Eddy Simulation (LES) over a 240 × 240 km 2 domain. While warm rain contributes to 1% of the total rainfall in the LES, its spatial extent accounts for 24% of the area covered by rainfall. Almost all the warm-rain cells tracked in the observation and the LES have a size between 2 and 10 km and a lifetime varying from 5 to 60 min. During the nighttime, warm-rain cells are caused by the dissipation of large deep-convection systems while during the daytime they are formed by the boundary-layer thermals. The vertical extension of the warm-rain cells is limited by vertical wind shear at their top. In the simulation, their top is 1.6 km higher with respect to the radar observations due to the large-scale environment given by wrong initial conditions. This study shows the challenge of simulating warm rain in southern West Africa, a key phenomenon during the little dry season

Fabrication of conductive interconnects by Ag migration in Cu-Ag core-shell nanoparticles

Fabrication of conductive nanoparticle films is observed in Cu-Ag core-shell nanoparticles by fast diffusion of Ag at 220 degrees C from particle surfaces, leading to the formation of sintered necks of Ag at the initial particle-particle contacts. Transmission electron microscopy showed that the necks were pure Ag and that particle surfaces away from the contacts were nearly Ag-free. The extent of neck formation is controllable by the choice of initial Ag thickness. Analysis of the thermodynamics of the Ag-Cu system and the relative diffusivities of Ag and Cu provide criteria for fabrication of other core-shell two-phase systems by the same mechanism

Amine-Thiol Solution Route Method for Fabricating CdxZn1-xS Thin Film Solar Cells

Cadmium zinc sulfide, CdZnS, is a promising material for the buffer layer of thin film solar cells because the alloy is considerably more cost effective and more optimizable than pure cadmium sulfide, CdS, in terms of band gap. The current fabrication methods of the buffer layer often require expensive equipment or produce undesirable impurities in the alloy. This study investigates a cost effective and scalable solution route method to synthesize the CdZnS buffer layer. Molecular precursors of CdZnS were dissolved in varying molecular ratios of cadmium and zinc in a mixture of hexylamine and propanethiol. The resulting alloys produced were characterized by XRD and UV-VIS spectroscopy to determine the crystallinity and band gap of the CdZnS alloy samples as a function of composition. The results from this investigation show that increasing concentrations of zinc in the precursor solutions and the resulting films increase the band gap of the material. The findings of this study support the feasibility of this solution route to synthesize a CdxZn1-xS buffer layer, and provokes a need for further investigation and optimization of this method

Efecto del fluoruro de rubidio en las propiedades optoelectrónicas de películas delgadas de CuInSe2 nanoestructuradas obtenidas por procesos por solución.

Chalcopyrite CuInSe2 (CISe) and Cu(In, Ga)(S, Se)2 (CIGS) absorber layers, have emerged as promising alternatives in the solar cell field due to their unique properties such as power conversion efficiencies (PCEs) above 20 %, direct bandgap, and high absorption coefficient. This enables the making of high-quality PV devices with absorbers from 2 μm thick, significantly reducing the use of raw materials. Additionally, the CISe absorber layer is a desirable material for Perovskite/CIS tandem configuration with a narrow band gap at the bottom that has demonstrated PCEs close to 25 %, and potential applications in lightweight and/or flexible substrates. Recently, the addition of alkali elements such as sodium, potassium, rubidium, and cesium via post-deposition techniques (PDTs) has demonstrated an improvement in CIGS-based solar cells’ performance. In this study, 10, 20, and 30 nm thick layers of rubidium fluoride were post-deposited on CISe-films made by solution processing techniques and then selenized under a selenium-argon atmosphere to improve the CISe photoelectronic properties such as the number of charge carriers collected and grain growth, critical characteristics to ensure useful photovoltaic devices. Thus, the effect of rubidium fluorine on CISe-based solar cells was analyzed using several characterization techniques. According to the results, thin films made by an amine-thiol mixture with uniform atomic composition were obtained. The crystallinity and grain growth improved with an increase in rubidium fluoride addition. Moreover, with 10 nm of rubidium fluoride, an improvement in the lifetime of the charge carrier, photoluminescence intensity, and the number of carriers collected by the solar cells was obtained.Las capas absorbentes de calcopirita CuInSe2 (CISe) y Cu(In, Ga)(S, Se)2 (CIGS) han surgido como alternativas prometedoras en el campo de las celdas solares debido a sus propiedades únicas tales como, eficiencias de conversión de energía (PCE) por encima del 20 %, bandgap directo y el alto coeficiente de absorción. Esto permite fabricar dispositivos fotovoltaicos de alta calidad con capas absorbentes de 2 μm de espesor, reduciendo significativamente el uso de materias primas. Además, la capa absorbente de CISe es un material deseable para la configuración en tándem de Perovskita/CIS con un estrecho bandgap en la parte inferior que ha demostrado PCE cercanos al 25 % y potenciales aplicaciones en sustratos ligeros y/o flexibles. Recientemente, la adición de elementos alcalinos como el sodio, el potasio, el rubidio y el cesio, mediante técnicas de posdeposición (PDT), ha demostrado una mejora en el rendimiento de las celdas solares basadas en CIGS. En este estudio se depositaron capas de 10, 20 y 30 nm de espesor de fluoruro de rubidio sobre películas de CIGS fabricadas mediante técnicas de procesamiento en solución, y luego se selenizaron bajo una atmósfera de selenio-argón para mejorar propiedades foto-electrónicas como el número de portadores de carga recolectados y crecimiento de grano, características esenciales para la obtención de dispositivos fotovoltaicos funcionales. Así, se analizó el efecto del fluoruro de rubidio en las celdas solares basadas en CISe mediante varias técnicas de caracterización. Según los resultados, se obtuvieron películas delgadas fabricadas con una mezcla de amina y tiol con una composición atómica uniforme. La cristalinidad y el crecimiento del grano mejoraron con el aumento de la adición de fluoruro de rubidio. Además, con 10 nm de fluoruro de rubidio, se obtuvo una mejora en el tiempo de vida del portador de carga, la intensidad de fotoluminiscencia y el número de portadores obtenidos por las celdas solares