Competition between supersolid phases and magnetisation plateaux in the frustrated easy-axis antiferromagnet on a triangular lattice

The majority of magnetic materials possess some degree of magnetic anisotropy, either at the level of a single ion, or in the exchange interactions between different magnetic ions. Where these exchange interactions are also frustrated, the competition between them and anisotropy can stabilize a wide variety of new phases in applied magnetic field. Motivated by the hexagonal delafossite 2H-AgNiO 2, we study the Heisenberg antiferromagnet on a layered triangular lattice with competing first- and second-neighbour interactions and single-ion easy-axis anisotropy. Using a combination of classical Monte Carlo simulation, mean-field analysis, and Landau theory, we establish the magnetic phase diagram of this model as a function of temperature and magnetic field for a fixed ratio of exchange interactions, but with values of easy-axis anisotropy D extending from the Heisenberg (D =0) to the Ising (D=&#8734) limits. We uncover a rich variety of different magnetic phases. These include several phases which are magnetic supersolids (in the sense of Matsuda and Tstuneto or Liu and Fisher), one of which may already have been observed in AgNiO 2. We explore how this particular supersolid arises through the closing of a gap in the spin-wave spectrum, and how it competes with rival collinear phases as the easy-axis anisotropy is increased. The finite temperature properties of this phase are found to be different from those of any previously studied magnetic supersolid.Comment: 25 pages; 29 figures; minor revisions; accepted for publication in Phys. Rev.

National case study: Portugal

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Understanding the impact of school´s ethnic composition on Mathematics results of students with immigrant origin in primary school

Scientific interest concerning the impact of school’s compositional effect on student performance has intensified throughout the current century, as the subject has been vastly explored by researchers in various national contexts (Agirdag, Van Houtte & Van Avermaet, 2012; Jensen & Rasmussen, 2011; Van der Slik, Driessen & De Bot, 2006; Schnepf, 2007; Goldsmith, 2003, Lleras, 2008). These effects have usually been studied taking student outcomes as measured by standardised tests on different school subjects and levels of education. In Portugal we conducted a research using an extensive database (16 269 students and 417 schools) with the results of fourth grade students on Portuguese Language national standardised tests in the Lisbon Metropolitan Area (2009-10). We intent to reveal what are the main factors behind students results in public schools giving special attention to the effect of ethnicity, considered both at the student level (its national origin) and at the school level (the schools ethnic composition). A multilevel analysis was developed involving both individual level variables and school level variables to answer the following research questions: Does the schools’ ethnic composition effect on Portuguese Language scores stand when students’ gender, social and ethnic origins are taken into account? Does this effect stand when the schools’ social composition is taken into account? How does the schools’ ethnic composition moderate the relation between having/not having an immigrant background and students’ Portuguese Language scores, when the socio-economic status (SES) of both students and schools is controlled?info:eu-repo/semantics/publishedVersio

The effect of school´s ethnic composition on Mathematics results of students with immigrant origin in primary school

Scientific interest in the impact of the school composition effect on student performance has been reflected in the literature for several decades (since Coleman, 1966) and has recently intensified. In Portugal, sociological research in this field has been scarce, in particular research based on extensive methodologies. Taking 1st Cycle students and their Mathematics results as reference, the present study sought to contribute to this field. The objective was to identify the main effect and the moderating effect of school composition (socioeconomic and ethnic) on students' results, controlling the effect of individual and school variables, whose effects on school outcomes are already known, such as socioeconomic status (SES), gender, school trajectory, and school size. We particularly sought to understand whether school composition affects the students’ results, and whether the effects vary with students’ national origins. The research was supported by an extensive database containing information on 23,143 students at 522 public schools in the Lisbon Metropolitan Area. A multilevel analysis was developed, considering student and school levels. The dependent variable was the Mathematics results of fourth-grade students in the 2015 National Attainment Test. We concluded that the effect of school’s social composition is more important to student performance than that of school’s ethnic composition and also that the students from PALOPs (Portuguese-speaking African Countries) benefit more than any others when they attend schools with a higher average SES.info:eu-repo/semantics/submittedVersio

Chronically shortened rod outer segments accompany photoreceptor cell death in Choroideremia

X-linked choroideremia (CHM) is a disease characterized by gradual retinal degeneration caused by loss of the Rab Escort Protein, REP1. Despite partial compensation by REP2 the disease is characterized by prenylation defects in multiple members of the Rab protein family that are master regulators of membrane traffic. Remarkably, the eye is the only organ affected in CHM patients, possibly because of the huge membrane traffic burden of the post mitotic photoreceptors, which synthesise outer segments, and the adjacent retinal pigment epithelium that degrades the spent portions each day. In this study, we aimed to identify defects in membrane traffic that might lead to photoreceptor cell death in CHM. In a heterozygous null female mouse model of CHM (Chmnull/WT), degeneration of the photoreceptor layer was clearly evident from increased numbers of TUNEL positive cells compared to age matched controls, small numbers of cells exhibiting signs of mitochondrial stress and greatly increased microglial infiltration. However, most rod photoreceptors exhibited remarkably normal morphology with well-formed outer segments and no discernible accumulation of transport vesicles in the inner segment. The major evidence of membrane trafficking defects was a shortening of rod outer segments that was evident at 2 months of age but remained constant over the period during which the cells die. A decrease in rhodopsin density found in the outer segment may underlie the outer segment shortening but does not lead to rhodopsin accumulation in the inner segment. Our data argue against defects in rhodopsin transport or outer segment renewal as triggers of cell death in CHM

Relação das famílias com a escolaridade e sucesso escolar: comparação entre famílias de origem cabo-verdiana, origem indiana e autóctones

A explicação para a desigualdade dos desempenhos escolares dada pelos profissionais da educação vem frequentemente associada à amplitude do apoio familiar à escolarização dos descendentes. Com o intuito de explorarmos esta relação analisam-se resultados de parte de um inquérito por questionário aplicado junto de crianças do 5º e 6º ano de escolaridade, onde foi possível identificar a trajectória escolar de cada aluno e as representações e práticas dos seus progenitores na relação com a escola. Trata-se de um total de 837 alunos distribuídos por 8 escolas dos concelhos de Lisboa e Loures, com diferentes origens nacionais. Compara-se a informação para os alunos autóctones, para os que têm origem cabo-verdiana e os que têm origem indiana. Concluímos que o apoio familiar à escolaridade (índice construído com base na ida às reuniões escolares, no controlo que exercem sobre os trabalhos de casa, no apoio prestado nas dificuldades e, ainda, no diálogo sobre a vida escolar) contribui para o desempenho escolar e que as duas variáveis variam numa relação directa. Contudo, esse apoio não constitui, de modo algum, uma condição suficiente ao êxito ou fracasso escolares, dado não ser pertinente concluir pelo efeito decisivo das práticas de apoio familiar à escolaridade sobre os resultados que os alunos obtêm na escola. Verificou-se, ainda, existir uma relação mais forte com os resultados obtidos quando se trata dos alunos de origem cabo-verdiana e mais frágil com são os de origem indiana.info:eu-repo/semantics/publishedVersio

Alunos estrangeiros e descendentes de imigrantes no sistema de ensino Português: Elementos de diagnóstico e de reflexão

A presente comunicação apresenta (i) dados relativos à evolução recente da situação dos alunos estrangeiros e/ou com origem na imigração nos diferentes níveis e modalidades de ensino em Portugal, (ii) algumas das medidas de política educativa que têm estes alunos como alvo, bem como (iii) resultados de investigação que importa considerar quando se pretendem desenhar políticas públicas que enfrentem os problemas identificados.info:eu-repo/semantics/publishedVersio

A relação das famílias imigradas com a escolaridade: comparando as famílias de origem cabo-verdiana e as de origem indiana

No âmbito do estudo da relação das famílias imigradas de origem indiana e cabo verdiana com a escolaridade dos seus descendentes quando estes se encontram a frequentar a escolaridade obrigatória (2º ciclo do Ensino Básico), procura se apreender as práticas de suporte que implementam bem como a idealização que fazem do percurso escolar dos seus descendentes. Trata-se de uma abordagem exploratória da informação recolhida através de um inquérito por questionário a alunos de escolas públicas dos concelhos de Lisboa e Loures (IALL) – aquelas em que era maior o contingente de alunos com o perfil desejado – num total de 837 alunos e de algumas entrevistas a membros das suas famílias. Das conclusões desta análise destaca-se a relação investida que as famílias imigradas tanto de origem cabo-verdiana como de origem indiana desenvolvem na relação com a escolaridade dos seus progenitores, dadas as práticas de suporte à escola que desenvolvem, não se registando diferenciações significativas em relação as famílias autóctones. Salienta-se, ainda, a amplitude dos pontos de apoio à escolaridade que se traduz, especialmente no caso das famílias de origem indiana, no recurso a uma rede considerável de pessoas exteriores ao núcleo familiar (amigos, vizinhos)

Top 50 most-cited articles in medicine and science in football

To conduct a comprehensive mapping analysis to the scientific literature published in football aiming to identify the areas of bigger interest and potential for further exploration.info:eu-repo/semantics/publishedVersio