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We study here experimentally, numerically and using a lubrication approach, the shape, velocity and lubrication film thickness distribution of a droplet rising in a vertical Hele-Shaw cell. The droplet is surrounded by a stationary immiscible fluid and moves purely due to buoyancy. A low density difference between the two media helps to operate in a regime with capillary number
is built with the surrounding oil viscosity
, the droplet velocity
and surface tension
. The experimental data show that in this regime the droplet velocity is not influenced by the thickness of the thin lubricating film and the dynamic meniscus. For iso-viscous cases, experimental and three-dimensional numerical results of the film thickness distribution agree well with each other. The mean film thickness is well captured by the Aussillous & Quéré (Phys. Fluids, vol. 12 (10), 2000, pp. 2367–2371) model with fitting parameters. The droplet also exhibits the ‘catamaran’ shape that has been identified experimentally for a pressure-driven counterpart (Huerre et al., Phys. Rev. Lett., vol. 115 (6), 2015, 064501). This pattern has been rationalized using a two-dimensional lubrication equation. In particular, we show that this peculiar film thickness distribution is intrinsically related to the anisotropy of the fluxes induced by the droplet’s motion.
The objective of the present study is to summarise trends in under- and over-nutrition in pregnant women on the Thailand–Myanmar border. Refugees contributed data from 1986 to 2016 and migrants from 1999 to 2016 for weight at first antenatal consultation. BMI and gestational weight gain (GWG) data were available during 2004–2016 when height was routinely measured. Risk factors for low and high BMI were analysed for <18·5 kg/m2 or ≥23 kg/m2, respectively. A total of 48 062 pregnancies over 30 years were available for weight analysis and 14 646 pregnancies over 13 years (2004–2016) had BMI measured in first trimester (<14 weeks’ gestational age). Mean weight at first antenatal consultation in any trimester increased over the 30-year period by 2·0 to 5·2 kg for all women. First trimester BMI has been increasing on average by 0·5 kg/m2 for refugees and 0·6 kg/m2 for migrants, every 5 years. The proportion of women with low BMI in the first trimester decreased from 16·7 to 12·7 % for refugees and 23·1 to 20·2 % for migrants, whereas high BMI increased markedly from 16·9 to 33·2 % for refugees and 12·3 to 28·4 % for migrants. Multivariate analysis demonstrated low BMI as positively associated with being Burman, Muslim, primigravid, having malaria during pregnancy and smoking, and negatively associated with refugee as opposed to migrant status. High BMI was positively associated with being Muslim and literate, and negatively associated with age, primigravida, malaria, anaemia and smoking. Mean GWG was 10·0 (sd 3·4), 9·5 (sd 3·6) and 8·3 (sd 4·3) kg, for low, normal and high WHO BMI categories for Asians, respectively.
This study aimed to investigate associations of health promotion and prevention regulatory foci with sports practice, and examined the Selection, Optimization and Compensation (SOC) process behind the positive relationship between health promotion focus and sports practice. A cross-sectional study was conducted with 513 French volunteer sports participants aged from 18 to 82. Participants completed an online self-report survey measuring health regulatory foci, SOC strategy, Amount of Sports Practice (ASP), health condition, and educational level. Path analysis main results (χ2 = 16.64; df = 5; p < .01; RMSEA = 0.067; CFI = 0.98; R2 = .24) demonstrated that ASP was positively related with health promotion focus (β = .13, p < .01), SOC strategy (β = .28, p < .001) and negatively related with health prevention focus (β = –.20, p < .001). SOC strategy was positively related with health promotion focus (β = .39, p < .001) and bootstrapping analyses revealed that this strategy partially mediated the positive relationship between health promotion focus and ASP, 95% CI [.13, .29]. Finally, additional analyses showed that it was specifically the elective selection, optimization and compensation sub-components of SOC strategy which played mediating roles in this link, [.13, .29] < 95% CI < [.13, .29]. For the first time in the literature, these results evidenced direct links between health regulatory foci and sports practice, and a mechanistic pathway between health promotion focus and sports practice. The theoretical and applied implications of these results for sports promotion are discussed.
Fainting on a plane is quite common, and stewards are used to taking care of things. Statistically, there is always a physician on board. This Letter to the Editor details a case report that deals with inappropriate pacemaker inhibition during a flight.
RocheNC, ThabouillotO, BouvierF, PauleP. Prepare for Take-Off: Fasten Your Seatbelt and Keep a Magnet in Your Pocket!. Prehosp Disaster Med. 2018;33(1):114–115.
We investigate the Rayleigh–Taylor instability of a thin liquid film coated on the inside of a cylinder whose axis is orthogonal to gravity. We are interested in the effects of geometry on the instability, and contrast our results with the classical case of a thin film coated under a flat substrate. In our problem, gravity is the destabilizing force at the origin of the instability, but also yields the progressive drainage and stretching of the coating along the cylinder’s wall. We find that this flow stabilizes the film, which is asymptotically stable to infinitesimal perturbations. However, the short-time algebraic growth that these perturbations can achieve promotes the formation of different patterns, whose nature depends on the Bond number that prescribes the relative magnitude of gravity and capillary forces. Our experiments indicate that a transverse instability arises and persists over time for moderate Bond numbers. The liquid accumulates in equally spaced rivulets whose dominant wavelength corresponds to the most amplified mode of the classical Rayleigh–Taylor instability. The formation of rivulets allows for a faster drainage of the liquid from top to bottom when compared to a uniform drainage. For higher Bond numbers, a two-dimensional stretched lattice of droplets is found to form on the top part of the cylinder. Rivulets and the lattice of droplets are inherently three-dimensional phenomena and therefore require a careful three-dimensional analysis. We found that the transition between the two types of pattern may be rationalized by a linear optimal transient growth analysis and nonlinear numerical simulations.
Falling liquid films on the underside of a plate or on the outside of a rotating cylinder are subject to a destabilizing body force. The evolution of the film topology is determined by interactions between the Kapitza and the Rayleigh–Taylor instability, leading to complex patterning of the film surface and eventually fluid detachment from the substrate. This study experimentally investigates the evolution of the surface topology for a film on the outside of a vertical rotating cylinder of large radius. Shear at the liquid/air interface is suppressed through an outer, co-rotating cylinder. The film evolution is captured through high speed visualization in dependence of the control parameters, namely Reynolds number and rotation frequency. An increasing influence of the Rayleigh–Taylor instability for an increasing destabilizing body force (increasing rotational speed of the cylinder) is most notably observed in the form of a decreasing inception length of rivulet structures dominating the film topology. Wavelength as well as inception length of rivulets match the predictions from linear stability analysis of the classical Rayleigh–Taylor problem. In this context, experimental and supporting numerical results suggest that the emergence of rivulets occurs for any non-zero value of the destabilizing body force after a given evolution length that decreases with increasing body force. Fluid detachment from the substrate is found to be intimately related to the existence of rivulet structures. In dependence of the control parameters, detaching droplets are either observed as a result of interactions of solitary pulses of varying phase speed on rivulets, directly after destabilization of two-dimensional waves into rivulets or immediately at the fluid inlet. By comparison to the convective/absolute instability transition predicted by linear stability analysis of an integral boundary layer formulation of the problem in question, it is shown that the prediction of a predominant dripping mechanism lies beyond the scope of linear analysis.
This is a case report of a 45-year-old man who reported complete amnesia during the very first kilometer of a 10-km run. He was wearing a heart rate monitor (HRM). The interrogation of his HRM watch showed 200 bpm tachycardia beginning in the first kilometer and increasing up to 220 bpm during the last kilometer. The patient was asked to wear a Holter-monitor (Holter Research Laboratory; Helena, Montana USA) electrocardiogram (ECG) while practicing a training session. This examination allowed for the diagnosis of an adrenergic paroxysmal atrial fibrillation (AF) with an impressive auriculo-ventricular conduction over 260 bpm. This case highlights that non-medical devices, such as connected watches, can be helpful to diagnose arrhythmias.
ThabouillotO, BostanciK, BouvierF, DumitrescuN, StéfuriacM, PauleP, RocheNC. Syncope During Competitive Events: Interrogating Heart Rate Monitor Watches May Be Useful!Prehosp Disaster Med. 2017;32(6):691–693
Accuracy of atom probe tomography measurements is strongly degraded by the presence of phases that have different evaporation fields. In particular, when there are perpendicular interfaces to the tip axis in the specimen, layers thicknesses are systematically biased and the resolution is degraded near the interfaces. Based on an analytical model of field evaporated emitter end-form, a new algorithm dedicated to the 3D reconstruction of multilayered samples was developed. Simulations of field evaporation of bilayer were performed to evaluate the effectiveness of the new algorithm. Compared to the standard state-of-the-art reconstruction methods, the present approach provides much more accurate analyzed volume, and the resolution is clearly improved near the interface. The ability of the algorithm to handle experimental data was also demonstrated. It is shown that the standard algorithm applied to the same data can commit an error on the layers thicknesses up to a factor 2. This new method is not constrained by the classical hemispherical specimen shape assumption.
Irradiation of reactor pressure vessel (RPV) steels causes the formation of nanoscale microstructural features (termed radiation damage), which affect the mechanical properties of the vessel. A key tool for characterizing these nanoscale features is atom probe tomography (APT), due to its high spatial resolution and the ability to identify different chemical species in three dimensions. Microstructural observations using APT can underpin development of a mechanistic understanding of defect formation. However, with atom probe analyses there are currently multiple methods for analyzing the data. This can result in inconsistencies between results obtained from different researchers and unnecessary scatter when combining data from multiple sources. This makes interpretation of results more complex and calibration of radiation damage models challenging. In this work simulations of a range of different microstructures are used to directly compare different cluster analysis algorithms and identify their strengths and weaknesses.
Whispering gallery modes (WGMs) have been widely studied over the past 20 years for various applications, including biological sensing. While the WGM-based sensing approaches reported in the literature have shown tremendous performance down to single molecule detection, at present such sensing technologies are not yet mature and still have significant practical constraints that limit their use in real-world applications. Our work has focused on developing a practical, yet effective, WGM-based sensing platform capable of being used as a dip sensor for in-vivo biosensing by combining WGM fluorescent microresonators with silica Microstructured Optical Fibers (MOFs).
We recently demonstrated that a suspended core MOF with a dye-doped polymer microresonator supporting WGMs positioned onto the tip of the fiber, can be used as a dip sensor. In this architecture the resonator is anchored to one of the MOF air holes, in contact with the fiber core, enabling a significant portion of the evanescent field from the fiber to overlap with the sphere and hence excite the fluorescent WGMs. This architecture allows for remote excitation and collection of the WGMs. The fiber also permits easy manipulation of the microresonator for dip sensing applications, and hence alleviates the need for a complex microfluidic interface. More importantly, it allows for an increase in both the excitation and collection efficiency compared to free space coupling, and also improves the Q factor.
In this paper we present our recent results on microstructured fiber tip WGM-based sensors and show that this sensing platform can be used in clinical diagnostics, for detecting various clinically relevant biomarkers in complex clinical samples.
Background: Current opinions regarding the use of dexamethasone in the treatment of chronic subdural hematomas (CSDH) are only based on observational studies. Moreover, the use of corticosteroids in asymptomatic or minimally symptomatic patient with this condition remains controversial. Here, we present data from a prospective randomized pilot study of CSDH patients treated with dexamethasone or placebo. Methods: Twenty patients with imaging-confirmed CSDH were recruited from a single center and randomized to receive dexamethasone (12 mg/day for 3 weeks followed by tapering) or placebo as a conservative treatment. Patients were followed for 6 months and the rate of success of conservative treatment with dexamethasone versus placebo was measured. Parameters such as hematoma thickness and clinical changes were also compared before and after treatment with chi-square tests. Adverse events and complications were documented. Results: During the 6-month follow-up, one of ten patients treated with corticosteroids had to undergo surgical drainage and three of ten patients were treated surgically after placebo treatment. At the end of the study, all remaining patients had complete radiological resolution. No significant differences were observed in terms of hematoma thickness profile and impression of change; however, patients experienced more severe side effects when treated with steroids as compared with placebo. Dexamethasone contributed to many serious adverse events. Conclusions: Given the small sample size, these preliminary results have not shown a clear beneficial effect of dexamethasone against placebo in our patients. However, the number of secondary effects reported was much greater for corticosteroids, and dexamethasone treatment was responsible for significant complications.
L’objectif de cette étude rétrospective était d’identifier les facteurs associés aux décomptes quotidiens de départs avant prise en charge médicale (DAPCM) dans les deux salles d’urgence du Centre hospitalier universitaire de Sherbrooke, Fleurimont (HF) et Hôtel-Dieu (HD).
Des données cliniques et démographiques anonymisées, ainsi que des données hospitalières, ont été extraites de la banque de données du Centre Informatisé de Recherche Évaluative en Services et Soins de Santé pour la période du 1er avril 2011 au 30 juin 2012. Les variables étant corrélées au nombre de DAPCM par jour par site lors des analyses univariées ont été retenues pour l’analyse de régression linéaire multivariée.
Les analyses de régression multivariées démontrent que le nombre de DAPCM par jour diminue pour les deux sites lorsque la durée moyenne de séjour des patients non hospitalisés à l’urgence diminue (HF:b=1,17, p<0,001; HD:b=1,41, p<0,001) et lorsqu’un médecin dédié aux patients ambulatoires est présent (HF:b=-4,35, p<0,001; HD:b=-5,48, p<0,001). De plus, des facteurs reliés à l’achalandage des salles d’urgence et la raison primaire de consultation ont également eu un effet sur le nombre de DAPCM par jour.
Des efforts devraient être faits afin de diminuer la durée moyenne de séjour des patients non hospitalisés à l’urgence et d’assurer la présence d’un médecin dédié aux patients ambulatoires pour diminuer le nombre de DAPCM.
An alternative approach for simulating the field evaporation process in atom probe tomography is presented. The model uses the electrostatic Robin’s equation to directly calculate charge distribution over the tip apex conducting surface, without the need for a supporting mesh. The partial ionization state of the surface atoms is at the core of the method. Indeed, each surface atom is considered as a point charge, which is representative of its evaporation probability. The computational efficiency is ensured by an adapted version of the Barnes–Hut N-body problem algorithm. Standard desorption maps for cubic structures are presented in order to demonstrate the effectiveness of the method.
Practice-based approaches in management scholarship and organizational communication studies have in the past mainly evolved along parallel trajectories. Nonetheless, their epistemological and ontological stances – mostly influenced by a pragmatic positioning – and their shared concern for ordinary day-to-day (organizational) practices make them complementary trends of literature that would benefit from a more systematic and engaged dialogue (for similar arguments, see Fenton and Langley 2011; Spee and Jarzabkowski 2011; Vásquez, Sergi and Cordelier 2013). Accordingly, this chapter is a first attempt to put together two bodies of literature, the strategy-as-practice and the communicative constitution of organization approaches – stemming, respectively, from practice-based studies and organizational communication – in order to explore the role of talk and text in strategy-making.
Let us first note that we engage in this dialogue as communication scholars interested in understanding processes of organizing by acknowledging the constitutive force of communication (Putnam and Nicotera 2009). We therefore take a particular point of view for studying organization, more broadly, and here, strategy-making, which is deeply informed by the three following premises: (1) to always start from (rather than arriving at) communication as the motto of every inquiry; (2) to take a broad definition of communication that acknowledges the material and social world in which it takes place; and (3) to account for the many kinds of languages, not only spoken and written, that participate in constituting organization and organizing (Cooren, Taylor and Van Every 2006; see also Cooren et al. 2011).
Applied to the study of strategy and strategy-making, this implies that we should not begin by looking at strategy as originating in the individual and his/her situation and then, subsequently, asking how it gets transmitted in communication. From a communicational approach, we focus on strategy – what it is, what it does – and we question the constitutive role of communication in this being and acting. We also extend this questioning to other forms of communication that do not pertain solely to human activity; texts, objects, architectural elements, as we will argue, also ‘communicate’, and thus take part in the making of strategy. Finally, while accounting for the key role of language as talk and text, we do not exclude other modes of communication, such as paralinguistic or non-human modalities, that can also allow us to fully explore how communication constitutes strategy.
We report an experimental study of a turbulent dynamo in a liquid metal flow. The semi-synthetic dynamo is achieved thanks to an induction process generated by the turbulent shearing motion of liquid gallium and a feedback loop with external amplification, using coils. The external amplification allows the excitation of the dynamo instability at magnetic Reynolds numbers of order-one. This semi-synthetic dynamo is studied here in a regime where saturation is achieved when Lorentz forces modify significantly the bulk flow structure. We describe the supercritical bifurcation, intermittent and saturated regimes, the scalings of the dynamo magnetic field and we detail the power budget. We also report self-killing dynamos for which the dynamo magnetic field cannot be sustained, when the flow is dominated by the action of Lorentz forces, and subcritical regimes in which the flow only sustains a dynamo when it is already dominated by the action of Lorentz forces.
Structural gray matter characteristics of anxiety remain unclear. The aim of this study was to assess the influence of current depressive symptoms and history of depression on the gray matter characteristics of trait anxiety.
Structural magnetic resonance imaging (MRI) data from 393 individuals aged 65 years or older were used. Regions of interest (ROIs) included the amygdala, anterior cingulate cortex (ACC), insula, orbitofrontal cortex (OFC), and temporal cortex. Trait anxiety was measured by the State-Trait Anxiety Inventory (STAI). Depression and depressive symptoms were measured using DSM-IV criteria and the Center for Epidemiological Studies Depression Scale (CESD).
After adjustments for sociodemographics and health-related variables, anxiety had a significant influence on the gray matter characteristics in all cortical ROIs. First, in participants without depression antecedents, higher trait anxiety was associated with a larger cortical thickness in all cortical ROIs. Second, in participants with a previous history of depression, higher trait anxiety was associated with a smaller cortical thickness in all cortical ROIs.
These results suggest that anxiety is related to cortical thickness differently in healthy older adults and in older adults with psychiatric antecedents. Anxiety associated with thinner cortical areas could reflect symptoms of a specific type of depression or a vulnerability to develop depression.
We model the transmission of a message on the complete graph with n vertices and limited resources. The vertices of the graph represent servers that may broadcast the message at random. Each server has a random emission capital that decreases at each emission. Quantities of interest are the number of servers that receive the information before the capital of all the informed servers is exhausted and the exhaustion time. We establish limit theorems (law of large numbers, central limit theorem and large deviation principle), as n → ∞, for the proportion of informed vertices before exhaustion and for the total duration. The analysis relies on a construction of the transmission procedure as a dynamical selection of successful nodes in a Galton–Watson tree with respect to the success epochs of the coupon collector problem.