Averaging methods for design of spacecraft hysteresis damper

This work deals with averaging methods for dynamics of attitude stabilization systems. The operation of passive gravity-gradient attitude stabilization systems involving hysteresis rods is described by discontinuous differential equations. We apply recently developed averaging techniques for discontinuous system in order to simplify its analysis and to perform parameter optimization. The results obtained using this analytic method are compared with those of numerical optimization.This research is supported by the Portuguese Foundation for Science and Technologies (FCT), the Portuguese Operational Programme for Competitiveness Factors (COMPETE), the Portuguese Strategic Reference Framework (QREN),and the European Regional Development Fund (FEDER)

Estudo comparativo da artrodese posterolateral e PLIF no tratamento da espondilolistesis degenerativa grau I ou II ? análise de 124 casos

Objetivo: Posterior Lumbar Interbody Fusion (PLIF) ou artrodese posterolateral (APL) são técnicas cirúrgicas válidas na espondilolistese degenerativa. Alterações biomecânicas no nível adjacente à artrodese aceleram alterações degenerativas. Na literatura discute-se o tratamento adequado. Este estudo comparativo avalia clínica, taxa de fusão, complicações, alterações degenerativas e instabilidade no nível adjacente. Material e Métodos: Retrospectivamente foram analisadas espondilolisteses degenerativas grau I e II de Meyerding tratadas com PLIF ou APL de Janeiro 2000 a Dezembro 2010 num total de 124 doentes, 45 PLIF e 79 APL. Recorreu-se à escala visual analógica (VAS), Oswestry Disability Index (ODI) e Short Form-36 (SF-36). No PLIF foi determinada artrodese por estabelecimento de pontes ósseas estáveis. A instabilidade na APL foi definida quando osteolise adjacente aos parafusos, deslizamento ou angulação no nível da fusão. Resultados: O follow-up foi 4.5±2.7 e 3.9±2.6 anos (1-11 anos) no PLIF e APL, respectivamente. Ocorreu fusão em 93.3% no PLIF e 74.7% na APL (p=0.008). O PLIF apresenta superioridade no VAS pós-operatório (p=0.01) e variação geral (p=0.002). O ODI pós-operatório no PLIF foi menor (p<0.001) e 2.2% permanecem com disfunção severa comparativamente com 19% na APL. O PLIF é superior em escalas do SF-36: Função Física (p=0.034), Limitação Emocional (p=0.037), Função Social (p=0.05) e Saúde Geral (p=0.02). A taxa de complicações foi 4.4% no PLIF e 12.6% na APL (p=0.2). Ambas as técnicas desenvolveram doença do disco adjacente. Conclusões: Em ambos os grupos verifica-se melhoria da qualidade de vida, no entanto, a médio prazo o PLIF mostra superioridade. Instabilidade pré-operatória pode ser indicativa da eleição de PLIF

Correlates of changes in BMI of children from the Azores islands

Objective: To model changes in body mass index (BMI), including its stability, and to investigate the association between physical activity, 1-mile run/walk and levels of gross motor coordination and BMI during 5 consecutive years. Design: A longitudinal study of children 6 years of age at baseline followed at annual intervals over 5 years. Subjects: A total of 285 children (143 boys and 142 girls) were enrolled in grade 1 (age 6 years) and followed through grade 5 (age 10 years). Measurements: BMI was recorded and physical activity was assessed by questionnaire, aerobic fitness was evaluated with the 1-mile run/walk and gross motor coordination was measured with the KTK test battery (Korperkoordination test fur Kinder). Multilevel modelling techniques were for the primary analysis. Results: Changes in BMI showed similar curvilinear trends in boys and girls, with ample inter-individual crossing trajectories that is, low tracking. Longitudinal changes in physical activity (PA) and aerobic fitness were not significantly associated with BMI-changes during the 5 years. Children who were more proficient in their motor coordination showed lower values of BMI during the 5 years. Conclusions: BMI trajectories of both boys and girls show low tracking of BMI-values. Considerable inter-individual variation exists both in baseline BMI-values and changes (velocity and acceleration) over time. PA and fitness were not associated with BMI-changes, but gross motor function was negatively associated with BMI-changes. No gender-specific associations were found. If confirmed in other populations these observations could be translated in the promotion of physical activities that improve gross motor function in children aged 6-10 years. This seems to be of major importance for the physical education curriculum of primary school children

Transcript of The Dory Derby Accident

This story is an excerpt from a longer interview that was collected as part of the Launching through the Surf: The Dory Fleet of Pacific City project. In this story, Don Grotjohn recounts an accident that occurred during a Dory Derby competition

Competição de cultivares de brócolos tipo cabeça única em Campo Grande.

O experimento foi conduzido na horta da UNIDERP, Campo Grande-MS, de junho a setembro de 2005. Objetivou-se avaliar o desempenho de diferentes cultivares de brócolos tipo cabeça única disponíveis no mercado para as condições edafoclimáticas de Campo Grande. Foram avaliadas oito cultivares comerciais: BRO68 (Rogers), Marathon (Sakata), Green Parasol (Takii), Centenário (Takii), Legacy (Asgrow), Magestic Crown (Asgrow), AF649 (Sakata) e Brócolis de Cabeça (Topseed). O delineamento experimental utilizado foi em blocos casualizados completos, com quatro repetições, sendo cada parcela composta por dez plantas. Foram realizadas seis colheitas, a partir de 89 dias após a semeadura, de acordo com formação da inflorescência e o ponto de colheita, independente do tamanho. Foram avaliadas as características massa fresca (g) e diâmetro da inflorescência (cm) e produtividade (t ha-1). Para cultivo em Campo Grande, as cultivares Centenário, AF649, BRO68 e Marathon são as mais indicadas para plantio entre junho a setembro, pela maior produtividade

To practice or not to practice? Designing higher education curriculum to boost employability

One important dimension of Higher education curriculum design pertains to the inclusion of internships in study programmes. These have been generally conceptualized as learning experiences capable of bridging theoretical knowledge and hands-on experiences. The underlying pedagogical relevance is based on the premise that internships create the possibility of contextualized learning, fostering both professional growth and students’ self-esteem and pro-activity (Little, 2006). Interns are provided with the opportunity of early networking, as they enrol in practical activities and professionally interact with other people, besides their academic teachers and their graduate colleagues (Alpert, Heaney, & Kuhn, 2009; Weible, 2009). Research concerning internships has extensively reported the overwhelming positive effect of internships. Nevertheless, a more recent trend in literature has argued that little has been said concerning the relationship between internships and graduate employment or employability. Wilton (2012), for example, argues that more needs to be understood about the characteristics and specificities of internships and the extent to which such characteristics are capable of overcoming the current concern over the increase of graduates’ unemployment rates. Research conducted on the Portuguese case based on a database of 1,168 study programmes of first cycle degrees sough to redress this gap. Besides demonstrating that study programmes which include internships (cooperative education) tend to generate lower levels of unemployment than those that do not include internships, this research has suggested that the nature and structure of internships significantly impacts on graduate unemployment rates. In specific, mandatory internships tend to outperform their optional counterpart in reducing graduate unemployment levels. Moreover, thin sandwich courses also seem to be more beneficial than thick sandwich courses, suggesting that expanding and diversifying internships throughout the curriculum can reduce graduate unemployment rates. These results strongly suggest that it is not (only) the internship learning experience per se that makes the difference considering graduate employability, but (also) the way those internship experiences are organized along the study programme. This poster is, thus, focused on the nature and structure of internships, assessing their implications for higher education curriculum design. It does so by exploring the perspectives of the main stakeholders involved in internships regarding their motivations; required efforts; and expected outcomes. Empirically, the poster is based on the content analysis of semi-structured individual interviews to units coordinators and also focus groups conducted with coordinators of study programmes; internship supervisors (both academics and employers); and also interns. Qualitative analysis has been sustained by the main learning models traditionally used in research on work-based learning and aims at identifying a set of principles related with internships design, and modes of embedding them along an entire course, which may contribute to the development of graduates’ employability. Reported findings may constitute an important primer for reflection on the design of pedagogical strategies that maximize the contextual learning outputs of internships in a more systematic way, being particularly relevant for leading academics, namely those involved in curriculum design

Numerical simulation of strongly nonlinear and dispersive waves using a Green-Naghdi model

We investigate here the ability of a Green-Naghdi model to reproduce strongly nonlinear and dispersive wave propagation. We test in particular the behavior of the new hybrid finite-volume and finite-difference splitting approach recently developed by the authors and collaborators on the challenging benchmark of waves propagating over a submerged bar. Such a configuration requires a model with very good dispersive properties, because of the high-order harmonics generated by topography-induced nonlinear interactions. We thus depart from the aforementioned work and choose to use a new Green-Naghdi system with improved frequency dispersion characteristics. The absence of dry areas also allows us to improve the treatment of the hyperbolic part of the equations. This leads to very satisfying results for the demanding benchmarks under consideration

A splitting approach for the fully nonlinear and weakly dispersive Green-Naghdi model

The fully nonlinear and weakly dispersive Green-Naghdi model for shallow water waves of large amplitude is studied. The original model is first recast under a new formulation more suitable for numerical resolution. An hybrid finite volume and finite difference splitting approach is then proposed. The hyperbolic part of the equations is handled with a high-order finite volume scheme allowing for breaking waves and dry areas. The dispersive part is treated with a classical finite difference approach. Extensive numerical validations are then performed in one horizontal dimension, relying both on analytical solutions and experimental data. The results show that our approach gives a good account of all the processes of wave transformation in coastal areas: shoaling, wave breaking and run-up

Direct stenting with the Bx VELOCITY balloon-expandable stent mounted on the Raptor rapid exchange delivery system versus predilatation in a European randomized Trial: the VELVET trial.

Abstract AIMS: This study examined the six-month angiographic results of direct coronary stenting, and compared the nine-month safety, efficacy and cost of this strategy versus stenting after balloon predilatation. METHODS: In phase I of VELVET, 122 patients (mean age = 62.3 +/- 10.1 years, 77% male, 11% with diabetes) with angina pectoris or myocardial ischemia resulting from a single de novo 51% to 95% coronary stenosis underwent direct stenting. The endpoints of phase I included angiographic findings and rates of major adverse cardiac events up to six months of follow-up. In phase II, 401 patients (mean age = 61.3 +/- 10.8 years, 79% male, 16% with diabetes) with angina pectoris or documented myocardial ischemia resulting from single or multiple, de novo or restenotic, coronary lesions were randomized between direc

Measurement of the cross-section and charge asymmetry of WW bosons produced in proton-proton collisions at s=8\sqrt{s}=8 TeV with the ATLAS detector

This paper presents measurements of the $W^+ \rightarrow \mu^+\nu$ and $W^- \rightarrow \mu^-\nu$ cross-sections and the associated charge asymmetry as a function of the absolute pseudorapidity of the decay muon. The data were collected in proton--proton collisions at a centre-of-mass energy of 8 TeV with the ATLAS experiment at the LHC and correspond to a total integrated luminosity of 20.2~\mbox{fb^{-1}}. The precision of the cross-section measurements varies between 0.8% to 1.5% as a function of the pseudorapidity, excluding the 1.9% uncertainty on the integrated luminosity. The charge asymmetry is measured with an uncertainty between 0.002 and 0.003. The results are compared with predictions based on next-to-next-to-leading-order calculations with various parton distribution functions and have the sensitivity to discriminate between them.Comment: 38 pages in total, author list starting page 22, 5 figures, 4 tables, submitted to EPJC. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2017-13