Stability and magnetic properties of Fe double-layers on Ir (111)

We investigate the interplay between the structural reconstruction and the magnetic properties of Fe doublelayers on Ir (111)-substrate using first-principles calculations based on density functional theory and mapping of the total energies on an atomistic spin model. We show that, if a second Fe monolayer is deposited on Fe/Ir (111), the stacking may change from hexagonal close-packed to bcc (110)-like accompanied by a reduction of symmetry from trigonal to centered rectangular. Although the bcc-like surface has a lower coordination, we find that this is the structural ground state. This reconstruction has a major impact on the magnetic structure. We investigate in detail the changes in the magnetic exchange interaction, the magnetocrystalline anisotropy, and the Dzyaloshinskii Moriya interaction depending on the stacking sequence of the Fe double-layer. Based on our findings, we suggest a new technique to engineer Dzyaloshinskii Moriya interactions in multilayer systems employing symmetry considerations. The resulting anisotropic Dzyaloshinskii-Moriya interactions may stabilize higher-order skyrmions or antiskyrmions

A construção social do pais negros e os pais da classe trabalhadora por diretores de escolas: Interromper ou jogar orientações políticas educacionais contraditórios e deficientes?

School principals, contending with competing characterizations of parents in education policy and society, may view parents in a number of ways. Two common understandings portray parents as authentic partners or, in contrast, simply supporters of the school’s agenda. This paper explores these characterizations by considering the possible link between principals’ understandings of parents and their approaches to parent engagement and/or shared decision making, especially in light of the ways that the social context and education policy construct parents of color and working class parents as deficient. We use the lens of social construction of target populations to add to the currently minimal literature that directly examines principals’ views of parents. We report findings of a multi-phase analysis of surveys of 667 elementary principals in the state of California and interviews with a subgroup of 34 of these principals. We explore how principals structured parent engagement and conceived of the goals and rationales for parent workshops, illustrating how they socially constructed the target population of parents, particularly parents of color and working class parents. We find that principals often constructed parents in terms of deficiencies and as needing to learn to better support school goals. Our findings have profound implications for advancing equity in schools.Los directores de las escuelas, que compiten con caracterizaciones competitivas de los padres en las políticas educativas y la sociedad, pueden ver a los padres de varias maneras. Dos entendimientos comunes describen a los padres como socios auténticos o, en contraste, simplemente como partidarios de la agenda de la escuela. Este documento explora estas caracterizaciones al considerar el posible vínculo entre la comprensión de los padres y sus enfoques de participación de padres y / o decisiones compartidas, especialmente a la luz de las formas en que el contexto social y la política educativa construyen padres de color y padres de clase trabajadora como deficiente. Usamos el lente de la construcción social de las poblaciones objetivo para agregar a la literatura actualmente mínima que examina directamente las opiniones de los directores sobre los padres. Divulgamos los resultados de un análisis de múltiples fases de encuestas de 667 directores de escuelas primarias en el estado de California y entrevistas con un subgrupo de 34 de estos directores. Exploramos cómo los directores estructuraron la participación de los padres y concibieron las metas y fundamentos de los talleres para padres, ilustrando cómo construyeron socialmente la población objetivo de padres, en particular los padres de color y los padres de la clase trabajadora. Encontramos que los directores a menudo construyen a los padres en términos de deficiencias y que necesitan aprender a apoyar mejor las metas escolares. Nuestros hallazgos tienen profundas implicaciones para avanzar la equidad en las escuelas.Diretores de escolas, corrida caracterizações competitivas de pais em política de educação e da sociedade pode ver os pais de várias maneiras. Dois entendimentos comuns descrevem os pais como parceiros autênticos ou, em contraste, simplesmente como defensores da agenda da escola. Este artigo explora essas caracterizações quando se considera a possível ligação entre os pais compreensivos e suas abordagens de envolvimento dos pais e / ou compartilhado, especialmente à luz das maneiras em que o contexto social e política educacional construir pais de opções de cores e pais da classe trabalhadora como deficientes. Usamos a lente da construção social de populações-alvo para adicionar à literatura atualmente mínimo que examina diretamente as opiniões dos diretores sobre os pais. Nós divulgar os resultados de uma pesquisa multifásico análise de 667 diretores de escola primária no estado da Califórnia e entrevistas com um subconjunto de 34 desses diretores. Explore como gerentes de participação dos pais e objetivos concebido e fundamentos de oficinas para pais, ilustrando como o alvo pais, especialmente pais de cor e da classe trabalhadora população pais construído socialmente estruturado. Descobrimos que os diretores muitas vezes constroem os pais em termos de deficiências e precisam aprender para melhor apoiar os objetivos escolares. Nossas descobertas têm profundas implicações para o avanço da equidade nas escolas

Revealing the correlation between real-space structure and chiral magnetic order at the atomic scale

We image simultaneously the geometric, electronic and magnetic structure of a buckled iron bilayer film that exhibits chiral magnetic order. We achieve this by combining spin-polarized scanning tunneling microscopy and magnetic exchange force microscopy (SPEX), to independently characterize the geometric as well as the electronic and magnetic structure of non-flat surfaces. This new SPEX imaging technique reveals the geometric height corrugation of the reconstruction lines resulting from strong strain relaxation in the bilayer, enabling the decomposition of the real-space from the eletronic structure at the atomic level, and the correlation with the resultant spin spiral ground state. By additionally utilizing adatom manipulation, we reveal the chiral magnetic ground state of portions of the unit cell that were not previously imaged with SP-STM alone. Using density functional theory (DFT), we investigate the structural and electronic properties of the reconstructed bilayer and identify the favorable stoichiometry regime in agreement with our experimental result

Overburndened and Underfunded: California Public Schools Amidst the Great Recession

Since 2008, many nations, including the United States, have struggled with the effects of a global recession. The state of California has been particularly impacted by the Great Recession. Unemployment rates in California are among the highest in the United States, and a weak fiscal environment has forced deep cutbacks to a variety of state services. This study uses California as a case to explore the effects of economic crisis on public schools and the students they serve. The study draws on two years of survey and interview data with a representative sample of public school principals across California. The data show that, during the Great Recession, students have experienced growing social welfare needs that often shape their well-being and their performance in schools. We also find that the capacity of public schools to meet these needs and provide quality education has been eroded by budget cuts. This study finds that schools primarily serving low-income families have been hardest hit during the recession, in part because they cannot raise private dollars to fill the gap left by public sector cuts. The Great Recession thus has undermined educational quality while producing widening educational inequality in California

Curved CMOS sensor: characterization of the first fully functional prototype

Many are the optical designs that generate curved focal planes for which field flattener must be implemented. This generally implies the use of more optical elements and a consequent loss of throughput and performances. With the recent development of curved sensor this can be avoided. This new technology has been gathering more and more attention from a very broad community, as the potential applications are multiple: from low-cost commercial to high impact scientific systems, to mass-market and on board cameras, defense and security, and astronomical community. We describe here the first concave curved CMOS detector developed within a collaboration between CNRS-LAM and CEA-LETI. This fully-functional detector 20Mpix (CMOSIS CMV20000) has been curved down to a radius of R_c =150mm over a size of 24x32mm^2. We present here the methodology adopted for its characterization and describe in detail all the results obtained. We also discuss the main components of noise, such as the readout noise, the fixed pattern noise and the dark current. Finally we provide a comparison with the at version of the same sensor in order to establish the impact of the curving process on the main characteristics of the sensor

ACO2 mutations: A novel phenotype associating severe optic atrophy and spastic paraplegia

International audienc

The physical oceanography of the transport of floating marine debris

Marine plastic debris floating on the ocean surface is a major environmental problem. However, its distribution in the ocean is poorly mapped, and most of the plastic waste estimated to have entered the ocean from land is unaccounted for. Better understanding of how plastic debris is transported from coastal and marine sources is crucial to quantify and close the global inventory of marine plastics, which in turn represents critical information for mitigation or policy strategies. At the same time, plastic is a unique tracer that provides an opportunity to learn more about the physics and dynamics of our ocean across multiple scales, from the Ekman convergence in basin-scale gyres to individual waves in the surfzone. In this review, we comprehensively discuss what is known about the different processes that govern the transport of floating marine plastic debris in both the open ocean and the coastal zones, based on the published literature and referring to insights from neighbouring fields such as oil spill dispersion, marine safety recovery, plankton connectivity, and others. We discuss how measurements of marine plastics (both in situ and in the laboratory), remote sensing, and numerical simulations can elucidate these processes and their interactions across spatio-temporal scales

Complex population structure and haplotype patterns in the Western European honey bee from sequencing a large panel of haploid drones:Sequencing haploid honey bee drones

International audienceHoney bee subspecies originate from specific geographical areas in Africa, Europe and the Middle East, and beekeepers interested in specific phenotypes have imported genetic material to regions outside of the bees' original range for use either in pure lines or controlled crosses. Moreover, imported drones are present in the environment and mate naturally with queens from the local subspecies. The resulting admixture complicates population genetics analyses, and population stratification can be a major problem for association studies. To better understand Western European honey bee populations, we produced a whole genome sequence and single nucleotide polymorphism (SNP) genotype data set from 870 haploid drones and demonstrate its utility for the identification of nine genetic backgrounds and various degrees of admixture in a subset of 629 samples. Five backgrounds identified correspond to subspecies, two to isolated populations on islands and two to managed populations. We also highlight several large haplotype blocks, some of which coincide with the position of centromeres. The largest is 3.6 Mb long and represents 21% of chromosome 11, with two major haplotypes corresponding to the two dominant genetic backgrounds identified. This large naturally phased data set is available as a single vcf file that can now serve as a reference for subsequent populations genomics studies in the honey bee, such as (i) selecting individuals of verified homogeneous genetic backgrounds as references, (ii) imputing genotypes from a lower-density data set generated by an SNP-chip or by low-pass sequencing, or (iii) selecting SNPs compatible with the requirements of genotyping chips

Complex population structure and haplotype patterns in the Western European honey bee from sequencing a large panel of haploid drones

Honey bee subspecies originate from specific geographical areas in Africa, Europe and the Middle East, and beekeepers interested in specific phenotypes have imported genetic material to regions outside of the bees' original range for use either in pure lines or controlled crosses. Moreover, imported drones are present in the environment and mate naturally with queens from the local subspecies. The resulting admixture complicates population genetics analyses, and population stratification can be a major problem for association studies. To better understand Western European honey bee populations, we produced a whole genome sequence and single nucleotide polymorphism (SNP) genotype data set from 870 haploid drones and demonstrate its utility for the identification of nine genetic backgrounds and various degrees of admixture in a subset of 629 samples. Five backgrounds identified correspond to subspecies, two to isolated populations on islands and two to managed populations. We also highlight several large haplotype blocks, some of which coincide with the position of centromeres. The largest is 3.6 Mb long and represents 21% of chromosome 11, with two major haplotypes corresponding to the two dominant genetic backgrounds identified. This large naturally phased data set is available as a single vcf file that can now serve as a reference for subsequent populations genomics studies in the honey bee, such as (i) selecting individuals of verified homogeneous genetic backgrounds as references, (ii) imputing genotypes from a lower-density data set generated by an SNP-chip or by low-pass sequencing, or (iii) selecting SNPs compatible with the requirements of genotyping chips.This work was performed in collaboration with the GeT platform, Toulouse (France), a partner of the National Infrastructure France Génomique, thanks to support by the Commissariat aux Grands Invetissements (ANR-10-INBS-0009). Bioinformatics analyses were performed on the GenoToul Bioinfo computer cluster. This work was funded by a grant from the INRA Département de Génétique Animale (INRA Animal Genetics division) and by the SeqApiPop programme, funded by the FranceAgriMer grant 14-21-AT. We thank John Kefuss for helpful discussions. We thank Andrew Abrahams for providing honey bee samples from Colonsay (Scotland), the Association Conservatoire de l'Abeille Noire Bretonne (ACANB) for samples from Ouessant (France), CETA de Savoie for sample from Savoie, ADAPI for samples from Porquerolles and all beekeepers and bee breeders who kindly participated in this study by providing samples from their colonies.info:eu-repo/semantics/publishedVersio