Fusion cross section measurements of astrophysical interest for light heavy ions systems within the STELLA project

This contribution is focused on the STELLA project (STELlar LAboratory), which aims at the measurement of fusion cross sections between light heavy ions like 12C+12C, 12C+16O or 16O+16O at deep subbarrier energies. The gamma-particle coincidence technique is used in order to reduce background contributions that become dominant for measurements in the nanobarn regime. The experimental setup composed of an ultra high vacuum reaction chamber, a set of 3 silicon strip detectors, up to 36 LaBr3(Ce) scintillators from the UK FATIMA collaboration, and a fast rotating target system will be described. The 12C+12C fusion reaction has been studied from Elab = 11 to 5.6 MeV using STELLA at the Andromède facility in Orsay, France. Preliminary commissioning results are presented in this article

Contextualização no ensino de estatística: uma proposta para os anos finais do ensino fundamental

Acompanha: Sequência de ensino contemplando a estatística nos anos finais do ensino fundamental segundo pressupostos da contextualizaçãoThe present study aimed to examine the contributions that a sequence of teaching based on assumptions of contextualization can bring to the teaching of statistics in the final years of basic school. The literature review concerning the teaching of statistics relies on Cazorla (2002), Lopes (2003, 2008, 2010a, 2010b), Silva (2007), Andrade (2008), Cazorla, Kataoka and Silva (2010), Jacobini et al. (2010), Campos, Wodewotzki and Jacobini (2011), among others. As for context, the literature review supported by Brazil (1998b, 1999), Tufano (2001), Pais (2002, 2010), Ramos (2004), (2005), Sadovsky (2007), Luccas (2011), among others. With the intention of achieving the proposed goal, was developed in the year 2011 a applied research, interpretive analysis and qualitative, descriptive in a batch of students of 7° year of basic school to a State public College of the city of Ponta Grossa, Paraná. The review of literature pertaining to the search features based on Gil (1991, 2006), Chizzotti (2003, 2008), Silva and Menezes (2005), Moreira and Caleffe (2008), Alves-Mazzotti (2011), Sarmento (2011), Teixeira (2011), among others. First was conducted an analysis of previous performance of the students on the basic content of statistics, based on a diagnostic instrument called pre-test. Then it was applied a sequence of teaching directed to basic statistical content, through the use of data collected in their own class, i.e. through contextualization. It emerged during the implementation of education, a greater interest and motivation of students to classes, as well as greater involvement of learners with the contents. The results of the analysis of the performance of the students after teaching sequence showed that this contributed to a significant gain on the acquisition of basic statistical content by students of the final years basic school. It is considered that the activities undertaken with learners, contributed to the development of the skills of reasoning, thinking, and statistical literacy of those forming the necessary basis for that in the future these students can reach the level of statistical literacy that contemporary society requires. As the final product of this work was to elaborate a courseware to support teacher education sequence containing a contextualized on basic statistical content aimed at the basic school, which is attached to this dissertation.O presente trabalho teve como objetivo analisar as contribuições que uma sequência de ensino pautada nos pressupostos da contextualização poderá trazer para o ensino e aprendizagem de Estatística nos anos finais do Ensino Fundamental. A revisão de literatura referente ao ensino de Estatística apoia-se em Cazorla (2002), Lopes (2003, 2008, 2010a, 2010b), Silva (2007), Andrade (2008), Cazorla, Kataoka e Silva (2010), Jacobini et al. (2010), Campos, Wodewotzki e Jacobini (2011), dentre outros. Quanto a contextualização, a revisão de literatura apoia-se em Brasil (1998b, 1999), Tufano (2001), Pais (2002, 2010), Ramos (2004), Mello (2005), Sadovsky (2007), Luccas (2011), além de outros. Com a intenção de alcançar o objetivo proposto, foi desenvolvida no ano de 2011 uma pesquisa aplicada, qualitativa com análise interpretativa e, descritiva em uma turma de alunos do 7° ano do Ensino Fundamental de um colégio público estadual do município de Ponta Grossa, Paraná. A revisão de literatura referente às características da pesquisa fundamenta-se em Gil (1991, 2006), Chizzotti (2003, 2008), Silva e Menezes (2005), Moreira e Caleffe (2008), Alves-Mazzotti (2011), Sarmento (2011), Teixeira (2011), dentre outros. Primeiramente foi realizada uma análise do desempenho prévio dos alunos em relação a conteúdos básicos de Estatística, tendo como base um instrumento diagnóstico chamado pré – teste. Depois foi aplicada uma sequência de ensino direcionada a conteúdos básicos de Estatística, por meio da utilização de dados coletados na própria turma, ou seja, por meio da contextualização. Verificou-se durante a aplicação da sequência de ensino, um maior interesse e motivação dos alunos para as aulas, além de um maior envolvimento dos educandos com os conteúdos estudados. Os resultados da análise do desempenho dos alunos após a aplicação da sequência de ensino mostraram que essa contribuiu para que houvesse um ganho significativo quanto à aquisição de conteúdos básicos de Estatística por parte de educandos dos anos finais do Ensino Fundamental. Considera-se que as atividades realizadas com os educandos, contribuíram para o desenvolvimento das competências de raciocínio, pensamento e, letramento estatísticos desses, formando a base necessária para que futuramente esses alunos possam atingir o nível de letramento estatístico que a sociedade contemporânea exige. Como produto final deste trabalho foi elaborado um material didático de apoio ao professor contendo uma sequência de ensino contextualizada sobre conteúdos básicos de Estatística voltada ao Ensino Fundamental, o qual se encontra anexado a esta dissertação

Contrasting Population Structures of Two Vectors of African Trypanosomoses in Burkina Faso: Consequences for Control

Tsetse flies are insects that transmit trypanosomes to humans (sleeping sickness) and animals (nagana). Controlling these vectors is a very efficient way to control these diseases. In Burkina Faso, a tsetse eradication campaign is presently targeting the northern part of the Mouhoun River Basin. To attain this objective, the approach has to be area-wide, i.e. the control effort targets an entire pest population within a circumscribed area. To assess the level of this isolation, we studied the genetic structure of Glossina palpalis gambiensis and Glossina tachinoides populations in the target area and in the adjacent river basins of the Comoé, the Niger and the Sissili River Basins. Our results suggest an absence of strong genetic isolation of the target populations. We therefore recommend establishing permanent buffer zones between the Mouhoun and the other river basin(s) to prevent reinvasion. This kind of study may be extended to other areas on other tsetse species

Identification of genetic variants associated with Huntington's disease progression: a genome-wide association study

Background Huntington's disease is caused by a CAG repeat expansion in the huntingtin gene, HTT. Age at onset has been used as a quantitative phenotype in genetic analysis looking for Huntington's disease modifiers, but is hard to define and not always available. Therefore, we aimed to generate a novel measure of disease progression and to identify genetic markers associated with this progression measure. Methods We generated a progression score on the basis of principal component analysis of prospectively acquired longitudinal changes in motor, cognitive, and imaging measures in the 218 indivduals in the TRACK-HD cohort of Huntington's disease gene mutation carriers (data collected 2008–11). We generated a parallel progression score using data from 1773 previously genotyped participants from the European Huntington's Disease Network REGISTRY study of Huntington's disease mutation carriers (data collected 2003–13). We did a genome-wide association analyses in terms of progression for 216 TRACK-HD participants and 1773 REGISTRY participants, then a meta-analysis of these results was undertaken. Findings Longitudinal motor, cognitive, and imaging scores were correlated with each other in TRACK-HD participants, justifying use of a single, cross-domain measure of disease progression in both studies. The TRACK-HD and REGISTRY progression measures were correlated with each other (r=0·674), and with age at onset (TRACK-HD, r=0·315; REGISTRY, r=0·234). The meta-analysis of progression in TRACK-HD and REGISTRY gave a genome-wide significant signal (p=1·12 × 10−10) on chromosome 5 spanning three genes: MSH3, DHFR, and MTRNR2L2. The genes in this locus were associated with progression in TRACK-HD (MSH3 p=2·94 × 10−8 DHFR p=8·37 × 10−7 MTRNR2L2 p=2·15 × 10−9) and to a lesser extent in REGISTRY (MSH3 p=9·36 × 10−4 DHFR p=8·45 × 10−4 MTRNR2L2 p=1·20 × 10−3). The lead single nucleotide polymorphism (SNP) in TRACK-HD (rs557874766) was genome-wide significant in the meta-analysis (p=1·58 × 10−8), and encodes an aminoacid change (Pro67Ala) in MSH3. In TRACK-HD, each copy of the minor allele at this SNP was associated with a 0·4 units per year (95% CI 0·16–0·66) reduction in the rate of change of the Unified Huntington's Disease Rating Scale (UHDRS) Total Motor Score, and a reduction of 0·12 units per year (95% CI 0·06–0·18) in the rate of change of UHDRS Total Functional Capacity score. These associations remained significant after adjusting for age of onset. Interpretation The multidomain progression measure in TRACK-HD was associated with a functional variant that was genome-wide significant in our meta-analysis. The association in only 216 participants implies that the progression measure is a sensitive reflection of disease burden, that the effect size at this locus is large, or both. Knockout of Msh3 reduces somatic expansion in Huntington's disease mouse models, suggesting this mechanism as an area for future therapeutic investigation

Fusion hindrance for the positive QQ-value system 12C+30Si^{12}\mathrm{C}+^{30}\mathrm{Si}

International audienceBackground: The fusion reaction C12+Si30 is a link between heavier cases studied in recent years, and the light heavy-ion systems, e.g., C12+C12, O16+O16 that have a prominent role in the dynamics of stellar evolution. C12+Si30 fusion itself is not a relevant process for astrophysics, but it is important to establish its behavior below the barrier, where couplings to low-lying collective modes and the hindrance phenomenon may determine the cross sections. The excitation function is presently completely unknown below the barrier for the C12+Si30 reaction, thus no reliable extrapolation into the astrophysical regime for the C+C and O+O cases can be performed. Purpose: Our aim was to carry out a complete measurement of the fusion excitation function of C12+Si30 from well below to above the Coulomb barrier, so as to clear up the consequence of couplings to low-lying states of Si30, and whether the hindrance effect appears in this relatively light system which has a positive Q value for fusion. This would have consequences for the extrapolated behavior to even lighter systems. Methods: The inverse kinematics was used by sending Si30 beams delivered from the XTU Tandem accelerator of INFN-Laboratori Nazionali di Legnaro onto thin C12 (50μg/cm2) targets enriched to 99.9% in mass 12. The fusion evaporation residues (ER) were detected at very forward angles, following beam separation by means of an electrostatic deflector. Angular distributions of ER were measured at Ebeam=45, 59, and 80 MeV, and they were angle integrated to derive total fusion cross sections. Results: The fusion excitation function of C12+Si30 was measured with high statistical accuracy, covering more than five orders of magnitude down to a lowest cross section ≃3μb. The logarithmic slope and the S factor have been extracted and we have convincing phenomenological evidence of the hindrance effect. These results have been compared with the calculations performed within the model that considers a damping of the coupling strength well inside the Coulomb barrier. Conclusions: The experimental data are consistent with the coupled-channels calculations. A better fit is obtained by using the Yukawa-plus-exponential potential and a damping of the coupling strengths inside the barrier. The degree of hindrance is much smaller than the one in heavier systems. Also a phenomenological estimate reproduces quite closely the hindrance threshold for C12+Si30, so that an extrapolation to the C+C and O+O cases can be reliably performed

Titan's Atmospheric Temperatures, Winds, and Composition

International audienceTemperatures obtained from early Cassini infrared observations of Titan show a stratopause at an altitude of 310 kilometers (and 186 kelvin at 15°S). Stratospheric temperatures are coldest in the winter northern hemisphere, with zonal winds reaching 160 meters per second. The concentrations of several stratospheric organic compounds are enhanced at mid- and high northern latitudes, and the strong zonal winds may inhibit mixing between these latitudes and the rest of Titan. Above the south pole, temperatures in the stratosphere are 4 to 5 kelvin cooler than at the equator. The stratospheric mole fractions of methane and carbon monoxide are (1.6 +/- 0.5) × 10-2 and (4.5 +/- 1.5) × 10-5, respectively

Reduced Cancer Incidence in Huntington's Disease: Analysis in the Registry Study

Background: People with Huntington's disease (HD) have been observed to have lower rates of cancers. Objective: To investigate the relationship between age of onset of HD, CAG repeat length, and cancer diagnosis. Methods: Data were obtained from the European Huntington's disease network REGISTRY study for 6540 subjects. Population cancer incidence was ascertained from the GLOBOCAN database to obtain standardised incidence ratios of cancers in the REGISTRY subjects. Results: 173/6528 HD REGISTRY subjects had had a cancer diagnosis. The age-standardised incidence rate of all cancers in the REGISTRY HD population was 0.26 (CI 0.22-0.30). Individual cancers showed a lower age-standardised incidence rate compared with the control population with prostate and colorectal cancers showing the lowest rates. There was no effect of CAG length on the likelihood of cancer, but a cancer diagnosis within the last year was associated with a greatly increased rate of HD onset (Hazard Ratio 18.94, p < 0.001). Conclusions: Cancer is less common than expected in the HD population, confirming previous reports. However, this does not appear to be related to CAG length in HTT. A recent diagnosis of cancer increases the risk of HD onset at any age, likely due to increased investigation following a cancer diagnosis