Flow patterns generated by oblate medusan jellyfish: field measurements and laboratory analyses

Flow patterns generated by medusan swimmers such as jellyfish are known to differ according the morphology of the various animal species. Oblate medusae have been previously observed to generate vortex ring structures during the propulsive cycle. Owing to the inherent physical coupling between locomotor and feeding structures in these animals, the dynamics of vortex ring formation must be robustly tuned to facilitate effective functioning of both systems. To understand how this is achieved, we employed dye visualization techniques on scyphomedusae (Aurelia aurita) observed swimming in their natural marine habitat. The flow created during each propulsive cycle consists of a toroidal starting vortex formed during the power swimming stroke, followed by a stopping vortex of opposite rotational sense generated during the recovery stroke. These two vortices merge in a laterally oriented vortex superstructure that induces flow both toward the subumbrellar feeding surfaces and downstream. The lateral vortex motif discovered here appears to be critical to the dual function of the medusa bell as a flow source for feeding and propulsion. Furthermore, vortices in the animal wake have a greater volume and closer spacing than predicted by prevailing models of medusan swimming. These effects are shown to be advantageous for feeding and swimming performance, and are an important consequence of vortex interactions that have been previously neglected

Heteronuclear ionizing collisions between laser-cooled metastable helium atoms

We have investigated cold ionizing heteronuclear collisions in dilute mixtures of metastable (2 3S1) 3He and 4He atoms, extending our previous work on the analogous homonuclear collisions [R. J. W. Stas et al., PRA 73, 032713 (2006)]. A simple theoretical model of such collisions enables us to calculate the heteronuclear ionization rate coefficient, for our quasi-unpolarized gas, in the absence of resonant light (T = 1.2 mK): K34(th) = 2.4*10^-10 cm^3/s. This calculation is supported by a measurement of K34 using magneto-optically trapped mixtures containing about 1*10^8 atoms of each species, K34(exp) = 2.5(8)*10^-10 cm^3/s. Theory and experiment show good agreement.Comment: 8 pages, 6 figure

Fisioterapia baseada em evidência e guidelines clínicas: atitudes, conhecimentos e implementação em educadores clínicos

ABSTRACT - Introduction – Evidence-based physiotherapy (EBP) is now well established in the teaching curricula, leading to expectations that students will have opportunities to implement EBP steps during internships. However, the position of clinical educators towards EBP can act against this educational process. Aims – Our aims were to describe for the first time EBP domains in clinical Portuguese educators and to quantify associations between individual exposures with EBP-related outcomes. Methods – A cross-sectional mail survey to clinical educators from the physiotherapy course of CESPU was conducted. Two mailings were sent to 289 contacts (separately and three weeks apart). Sociodemographic and postgraduate information was collected as exposure variables and a questionnaire on EBP domains was created. Results – There was a positive attitude towards EBP (all five questions ≥87%). Although 25% of the sample received no training in EBP, almost all of the participants reported knowing how to ‘ask’, ‘search’, and ‘critically appraise’. Only 60% of educators used clinical guidelines and less than half could integrate their recommendations into practice. Complementary training between 16h-30h/per year was positively associated with different aspects of EBP (all documented at p≤0.009), with decreasing trends in the strength of the associations after those intermediate values. Discussion – Although the picture of EBP domains among clinical educators seemed quite regular in comparison with other samples, only 60% of them declared using clinical guidelines in their practice (vs. 86%). Conclusions – Clinical educators in physiotherapy seem to have a positive attitude towards EBP with high levels of previous training in the area. However, the use of Clinical Guidelines and how to integrate their recommendation into practice both need to be promoted. The target range for complementary training seems to be between 16-30h/per year. Out of this scenario, there appears to exist an excessive focus on the component of ‘clinical expertise’ of EBP.RESUMO - Introdução – A prática baseada em evidência (PBE) encontra-se bem estabelecida na formação dos estudantes de fisioterapia e, por isso, é esperado que eles venham a ter oportunidade de a aplicar durante os estágios clínicos. No entanto, o posicionamento dos educadores clínicos relativamente à PBE pode impedir este processo educacional. Objetivos – Descrever pela primeira vez domínios da PBE em educadores clínicos Portugueses e quantificar as associações entre as suas características individuais e a PBE. Métodos – Um levantamento de dados transversal através de email foi realizado em educadores clínicos do curso de fisioterapia da CESPU. Dois emails foram enviados a 289 contactos (separados temporalmente em três semanas). Informação socio-demográfica e pós-graduada foi recolhida como variáveis de exposição. Foi criado um questionário relativo aos diferentes domínios da PBE. Resultados – Observou-se uma atitude positiva quanto à PBE (cinco questões avaliadas ≥87%). Apesar de 25% dos clínicos não terem recebido formação em PBE, quase todos reportaram saber “questionar”, “procurar” e “avaliar criticamente”. Apenas 60% reportaram usar guidelines clínicas. Treino complementar entre 16h-30h/ano esteve associado de forma positiva com diferentes aspetos da PBE (p≤0,009), com tendências decrescentes na força da associação após esses valores intermédios. Discussão – As estimativas de PBE encontradas em educadores clínicos parecem similares às previamente reportadas, mas apenas 60% dos educadores declarou usar guidelines clínicas na sua prática (comparativamente a 86%). Conclusões – Educadores clínicos em fisioterapia parecem possuir uma atitude positiva relativamente à PBE e demonstram níveis elevados de treino nesta área. No entanto, o uso de guidelines clínicas no contexto clínico da fisioterapia necessita ser promovido. O nível ideal de treino complementar parece encontrar-se entre as 16-30h/ano, pois à medida que essas horas aumentam uma maior atenção à componente de expertise clínica da PBE parece ocorrer.info:eu-repo/semantics/publishedVersio

In vivo anomalous diffusion and weak ergodicity breaking of lipid granules

Combining extensive single particle tracking microscopy data of endogenous lipid granules in living fission yeast cells with analytical results we show evidence for anomalous diffusion and weak ergodicity breaking. Namely we demonstrate that at short times the granules perform subdiffusion according to the laws of continuous time random walk theory. The associated violation of ergodicity leads to a characteristic turnover between two scaling regimes of the time averaged mean squared displacement. At longer times the granule motion is consistent with fractional Brownian motion.Comment: 4 pages, 4 figures, REVTeX. Supplementary Material. Physical Review Letters, at pres

Active Experiments Beyond the Earth: Plasma Effects of Sounding Radar Operations in the Ionospheres of Venus, Mars, and the Jovian System

The operation of powerful satellite- and rocket-born sounding radars is often accompanied by a heating/acceleration of the local electrons and ions. Intense fluxes of sounder accelerated particles were detected in Earth's ionosphere when the frequency of the radar transmitter was close to one of the fundamental plasma resonances: harmonic of the electron-cyclotron frequency, plasma, or upper-hybrid frequencies. Recently it was found that running a sounder in the ionosphere of the non-magnetized Mars results in similar effects. Ion and electron sensors of the ASPERA-3 experiment (Analyzer of Space Plasma and Energetic neutral Atoms) onboard the Mars Express spacecraft discovered acceleration of the local ionospheric ions and electrons from thermal threshold energies to 100's of eV during the active sounding phase of the onboard sounder. ESA and NASA missions being studied or under development to Jupiter (JUICE- JUpiter ICy moon Explorer) in 2022, Europa Clipper in 2023 and to Venus (EnVision) in 2032 and ISRO Venus obiter in 2023 will also carry powerful sounding radars. The purpose of this study is to investigate what mechanisms can cause acceleration of the plasma particles during operations of the proposed sounding radars in the Jovian system and Venusian ionosphere. Using the results of the previous studies and characteristics of the proposed sounding radars onboard JUICE, Europa Clipper, EnVision, and ISRO Venus Obiter, we define the optimal conditions for observations of sounder accelerated particles, depending on the local conditions, such as plasma density, composition, and intensity of the magnetic field. The EnVision and ISRO Venus Obiter radar operations are expected to result in the most pronounced acceleration of ions and electrons, an effect that can be used to improve the local plasma diagnostics