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L’insomnie chronique est un problème de santé publique touchant 10 % à 20 % de la population générale selon les études, et survenant à tout âge . Les comportements inadaptés d’hygiène de sommeil constituent les principaux facteurs de risque de trouble du sommeil chez le sujet jeune. Qu’en est-il dans une population d’internes en médecine, soumise à un travail à horaires décalés (gardes et astreintes) ? Nous avons interrogé 724 internes de médecine (spécialités médicales, chirurgie, anesthésie-réanimation, gynécologie médicale et obstétrique, et pédiatrie), du Nord-Pas-de-Calais, lors des répartitions de stage pour l’été 2015. Nous leur avons proposé une échelle de Pittsburgh (PSQI) et un questionnaire concernant leurs habitudes de vie. Sur 724 internes présents, 659 questionnaires remplis ont été recueillis (91 % de participation). Le score au PSQI est pathologique dans 37 % des cas (score > 5). Trois items semblent poser des difficultés spécifiques (troubles de l’endormissement, difficultés de maintien de l’éveil et enthousiasme à la réalisation des activités quotidiennes). La dégradation de ces caractéristiques est probablement en lien avec certains aspects d’hygiène de vie (écrans, excitants) mais également avec la difficulté à gérer les gardes hospitalières. Ces résultats sont du même ordre de grandeur que les données d’une étude américaine réalisée sur le même type de population en 2010 . Ils posent le problème de la gestion du sommeil dans une population jeune, en travail à horaires décalés atypiques, et confrontée à un niveau de responsabilité important. Travailler les comportements par rapport au sommeil, en les adaptant à l’âge des sujets et au travail à horaires décalés, pourrait s’avérer une piste de réflexion ultérieure indispensable.
L’accès aux soins des personnes à risque constitue un pilier essentiel de la prévention du suicide. Cependant, les idées reçues véhiculées autour des conduites suicidaires y opposent un obstacle significatif. Afin de cibler au mieux les campagnes d’information qui dissiperaient ces mythes, et pour en évaluer l’efficacité, les connaissances sur le suicide devraient pouvoir être quantifiées de façon fiable. À ce jour, seules quelques études anglo-saxonnes dédiées ont été validées. La limite décisive à leur interprétation tient cependant à ce qu’elles ne permettent pas d’approche normative. En effet, l’exactitude de leurs propositions n’est validée par aucun étalon officiel, alors même que certaines relèvent plus de l’expérience clinique que de connaissances issues de la littérature. Notre objectif consiste à palier cette limite en proposant une échelle dont la cotation est adaptée à l’évaluation d’un savoir normé. Le Questionnaire d’Évaluation des Connaissances sur le Suicide (QECS) est un auto-questionnaire qui explore, en 35 items, les principales connaissances relatives à l’épidémiologie et aux mythes communs concernant le suicide. Les réponses y sont recueillies par échelle visuelle analogique. La cotation finale se fait en confrontant ces réponses à celles d’un panel de référence constitué de spécialistes en suicidologie (n = 47). Nous présentons ici les résultats de ce panel, ainsi qu’une illustration des potentialités d’interprétation du QECS, via l’évaluation des connaissances d’un échantillon test d’étudiants en journalisme (n = 111). Les réponses du panel de référence étaient significativement différentes de « ni accord, ni désaccord » pour 27 des 29 items dédiés aux mythes. Pour 25 de ces items, une différence significative était retrouvée entre l’échantillon test et le panel de référence. Ainsi attestée, l’existence d’un avis expertal spécifique a servi d’étalon pour 2 modes de cotation des réponses de l’échantillon test : un score de véracité et un score de concordance aux experts.
Malgré les efforts fournis ces dernières années, le bilan de la prise en charge des patients bipolaires reste toujours insatisfaisant, tant du point de vue du retard diagnostique (8 à 10 ans en moyenne ) que des rechutes thymiques (50 % à 1 an ) et de la suicidalité, mais aussi concernant la morbidité cardiovasculaire (on rappellera que la principale cause de décès chez ces patients reste à ce jour les accidents cardiovasculaires). Face à ce constat, une nouvelle approche multidisciplinaire se développe depuis quelques années . Dans ce nouveau paradigme faisant appel bien entendu à la psychiatrie mais aussi à l’endocrinologie ou encore la cardiologie, la médecine du sommeil pourrait tenir un rôle de premier plan si l’on en juge par les comorbidités retrouvées aussi bien en périodes critiques qu’en périodes « dites » intercritiques. Ainsi, est-il convenu que les épisodes thymiques entraînent des troubles du sommeil, mais aussi que certains troubles du sommeil (rythmes irréguliers, insomnie, apnées…) sont des facteurs de rechutes thymiques. La force de l’association statistique pourrait, par ailleurs, nous permettre de considérer que certains troubles du sommeil sont à considérer comme une dimension du trouble bipolaire. De nombreuses études (avec malheureusement des faiblesses méthodologiques) retrouvent ainsi une association troublante entre troubles bipolaires et SAS, qui concernerait même près de la moitié des patients bipolaires . Devant les difficultés diagnostiques et thérapeutiques évoquées précédemment, et si l’on parvient à confirmer qu’environ la moitié des bipolaires est apnéique (étude en cours dans notre établissement de psychiatrie), un dépistage systématique du SAOS chez des sujets suspectés de bipolarité ou résistants à une prise en charge psychiatrique « standard » permettrait une optimisation des soins (amélioration des troubles du sommeil, traitement au moins partiel de l’épisode thymique , diminution du risque de rechute thymique, prévention cardiovasculaire, recommandations sur le choix des psychotropes).
Over 50% of adult disability claimants fail some form of SVT. While some over report psychological, affective symptoms, others may report incredible cognitive symptoms. We examined effects of different types of response bias on free recall and self-reported depression.
Participants and methods This is a single site cross-sectional study using a convenience sample (n = 224) of disability claimants in the Netherlands. The Green Word Memory Test (GWMT) was administered to all subjects. The Amsterdam Short Term Memory Test (AKTG), the Structured Inventory of Malingered. Symptomatology (SIMS), and the beck depression inventory (BDI-II) were administered in subsamples. Participant classification according to GWMT and SIMS outcomes resulted in four groups, G+/S+, G+/S−, G−/S+ and G−/S−.
Average age of the participants was 46.3 years (SD 9.9), 41.5% were female, and 43% were higher educated. GWMT was positive in 48.2% of all subjects, and 27.6% scored positive on both GWMT and SIMS. Analysis of variance of GWMT Free recall and Beck depression scores showed significant group differences [F(3, 123) = 33.21, P = .000] and [F(3, 106) = 25.17, P = .000] respectively.
Non credible test performance was prevalent in this Dutch study of disability claimants. Insufficient effort and over reporting of psychological symptoms are associated with different score profiles on regular tests and self-rating scales.
Disclosure of interest
The author receives funding for his work as a neuropsychologist in an expertise setting.
In this study, stereo particle imaging velocimetry measurements are performed at multiple streamwise locations behind a yawed wind turbine to reveal the formation mechanisms of the counter-rotating vortex pair (CVP), and a point vortex transportation (PVT) model is proposed to reproduce the top–down asymmetric kidney-shaped wake (also referred to as a curled wake). Results indicate that the CVP formed behind a yawed wind turbine originates from the complex interactions between the hub vortex and the streamwise components of the blade tip vortices, which is fundamentally different from the case of a yawed drag disk where the hub vortex is absent. Specifically, when the yaw angle exceeds a critical value, a small part of the streamwise vorticity shed from the rotor disk edge switches its sign from negative to positive and subsequently merges with the concentrated hub vortex under mutual induction, creating a patch of positive vorticity; meanwhile, the remaining streamwise vorticity distributed along the rotor edge curls and evolves into another patch of negative vorticity. These two patches of streamwise vorticity essentially constitute the CVP. Based on the physics learnt from the experiments, the non-uniform cross-stream velocity fields are first reconstructed by a cloud of point vortices distributed along the rotor edge and a hub vortex located in the rotor centre, and subsequently used to numerically solve a simplified transportation–diffusion equation of the wake velocity deficit, which altogether constitute the PVT model. This physics-based reduced-order model is the first model capable of accurately reproducing the wake deformation behind a yawed wind turbine.
Analytical wind turbine wake models and wake superposition methods are prevailing tools widely adopted by the wind energy community to predict the power production of wind farms. However, none of the existing wake superposition methods conserve the streamwise momentum. In this study, a novel wake superposition method capable of conserving the total momentum deficit in the streamwise direction is derived theoretically, and its performance is validated with both particle imaging velocimetry measurements and large-eddy simulation results. Detailed inter-method comparisons show that the novel wake superposition method outperforms all the existing methods by delivering an accurate prediction of the power production and the centreline wake velocity deficit, with a typical error of less than 5 % (excluding the near-wake region). Additionally, the momentum-conserving wake superposition method is extended to combine the transverse velocities induced by yawed wind turbines, and the secondary wake steering effect crucial to the power optimization in active wake control is well reproduced.
Variability of the rotor aspect ratio is one of the inherent characteristics of vertical-axis wind turbines (VAWTs) which differentiates them especially from the more conventional horizontal-axis wind turbines. In this study, we intend to investigate the effect of rotor aspect ratio on VAWT wakes. In particular, we aim to find out whether a common behaviour exists in the mean flow field of such wakes. In order to do so, we first design and perform a set of numerical experiments (using our already validated large-eddy simulation framework) to obtain the mean flow field of the wakes of three VAWTs of different aspect ratio (2, 1 and
) and the same thrust coefficient (
). After observing the obvious differences in these three wakes, by using the classical momentum integral and the concept of momentum diameter, we come up with an appropriate normalization length scale
is the rotor diameter and
is the rotor height. By normalizing the lengths (both streamwise and lateral) involved in the mean velocity profiles by
, we obtain a remarkable collapse of the wake profiles for the three aspect ratios. As a corollary, cross-sections of wakes of turbines with different aspect ratios eventually converge to a circular shape – not an elliptical one, for example, as one might presume intuitively. This result influences the modelling of VAWT far wakes and, in turn, has implications on the optimal configuration of VAWT farms.
Understanding and predicting the behaviour of wind turbine wake flows over hills is important for optimal design of wind-farm configurations on topography. In this study, we present an analytical modelling framework together with large-eddy simulation (LES) results to investigate turbine wakes over two-dimensional hills. The analytical model consists of two steps. In the first step, we deal with the effect of the pressure gradient on the wake evolution; and in the second step, we consider the effect of the hill-induced streamline distortion on the wake. This model enables us to obtain the wake recovery rate, the mean velocity and velocity deficit profiles and the wake trajectory in the presence of the hill. Moreover, we perform LES to test our model and also to obtain new complementary insight about such flows. Especially, we take advantage of the LES data to perform a special analysis of the behaviour of the wake on the leeward side of the hill. It is found that the mainly favourable pressure gradient on the windward side of the hill accelerates the wake recovery and the adverse pressure gradient on the leeward side decelerates it. The wake trajectory for a hill of the same height as the turbine’s hub height is found to closely follow the hill profile on the windward side, but it maintains an almost constant elevation (a horizontal line) downstream of the hilltop. The trajectory of the wake on the leeward side is also studied for a limiting case of an escarpment, and it is shown that an internal boundary layer forms on the plateau which leads to an upward displacement of the wake centre. Finally, a parametric study of the position of the turbine with respect to the hill is performed to further elucidate the effect of the hill-induced pressure gradient on the wind turbine wake recovery.
Between them, the chancellorships of the “two Helmuts” span nearly a quarter-century of German history. Helmut Schmidt led the country from 1974 to 1982; his successor, Helmut Kohl, served until 1998. But the verdict on their respective tenures has been very different. Kohl was seen as a bumbling provincial when he came to office in 1982 but, by the end of his second term, he had won a place in the history books as the “Chancellor of Unity” (Einheitskanzler). By the time he lost the election for what would have been his fifth term, he was hailed as the “master-builder” (Baumeister) of Europe for his decisive role in furthering the European Community's political and economic integration through the Maastricht Treaty and the introduction of the Euro. Schmidt, by contrast, came to office with a reputation for high administrative competence and intellectual prowess, but left the chancellery under a cloud. Der Spiegel spoke for many commentators when it dismissed him as a “good chancellor with a bad record”; few features of his period in office stood out as “proof of success.” Schmidt, it was said, had been a mere crisis manager and “problem-solver” (Macher) who lacked broader vision, so that “little endured of historical significance.” This has also been the verdict of many historians.
I noticed the dynamic relation between age and narrative the second time i read edith wharton's the house of mirth. on my first experience of reading the novel, as an undergraduate of eighteen, I was engaged by its thwarted love story and saddened by Lily Bart's tragic but honorable end. When I reread the novel in graduate school, however, I was about to turn twenty-nine, the age at which Lily's marriage prospects and high expectations for the future begin to fade. Although Lily is widely admired for her remarkable beauty, readers are alerted in the novel's opening pages to the incipient erosion of that beauty. Even as Lawrence Selden finds his eyes “refreshed” when he catches a glimpse of Lily at Grand Central Station, remarking that “he had never seen her more radiant” (37), he credits this impression to the way her dark hat and veil have temporarily restored “the girlish smoothness, the purity of tint, that she was beginning to lose after eleven years of late hours and indefatigable dancing” (38). While Selden silently muses about her age (“here was nothing new about Lily Bart. … [H]ad she indeed reached the nine-and-twentieth birthday with which her rivals credited her?” [37–38]), Lily declares that she's “as old as the hills” (38); she perceives that “people are getting tired” of her and saying she “ought to marry” (42). Lily is ambivalent about marriage as her “vocation” (as Selden puts it ) but undertakes this quest. By the end of the novel, having lost her social and economic standing and failed to secure a husband—and thereby a future—she puts her affairs in order and overdoses on chloral (43). Her age is certainly not the only factor contributing to her decline: Selden's continuing fascination with Lily affirms that she has remained dis-tractingly attractive (even if, perhaps, “ever so slightly brightened by art” ), and the novel attributes her social descent more directly to her financial circumstances than to her age. Nevertheless, the opening scene of The House of Mirth emphatically establishes twenty-nine as a precipice over which Lily Bart falls to her doom.
Turbulent axisymmetric wakes under pressure gradient have received little attention in the literature, in spite of their fundamental and practical importance, for example, in the case of wind turbine wakes over topography. In this paper, we develop an analytical framework to analyse turbulent axisymmetric wakes under different pressure gradient conditions. Specifically, we develop a model to predict how an arbitrary imposed pressure gradient perturbs the evolution of the zero-pressure-gradient wake. The starting point of the model is the basic mean conservation of the streamwise momentum equation. We take advantage of the self-similarity of the wake velocity deficit and the assumption that the ratio of the maximum velocity deficit to the wake width is independent of the pressure gradient; such an assumption is supported experimentally for planar wakes, and numerically for axisymmetric wakes in this study. Furthermore, an asymptotic solution for the problem is also derived. The problem is considered for both an axisymmetric strain and a planar strain. The inputs to the model are the imposed pressure gradient and the wake width in the zero-pressure-gradient case. To validate the model results, a set of large-eddy simulations (LES) are performed. Comparing the evolution of the maximum velocity deficit and the wake width, the model results and the LES data show good agreement. Similarly to planar wakes, it is observed that the axisymmetric wake recovers faster in the favourable pressure gradient compared with the adverse one.
Objectives: The aim of this study was to explore the risk assessment tools and criteria used to assess the risk of medical devices in hospitals, and to explore the link between the risk of a medical device and how those risks impact or alter the training of staff.
Methods: Within a broader questionnaire on implementation of a national guideline, we collected quantitative data regarding the types of risk assessment tools used in hospitals and the training of healthcare staff.
Results: The response rate for the questionnaire was 81 percent; a total of sixty-five of eighty Dutch hospitals. All hospitals use a risk assessment tool and the biggest cluster (40 percent) use a tool developed internally. The criteria used to assess risk most often are: the function of the device (92 percent), the severity of adverse events (88 percent) and the frequency of use (77 percent). Forty-seven of fifty-six hospitals (84 percent) base their training on the risk associated with a medical device. For medium- and high-risk devices, the main method is practical training. As risk increases, the amount and type of training and examination increases.
Conclusions: Dutch hospitals use a wide range of tools to assess the risk of medical devices. These tools are often based on the same criteria: the function of the device, the potential severity of adverse events, and the frequency of use. Furthermore, these tools are used to determine the amount and type of training required for staff. If the risk of a device is higher, then the training and examination is more extensive.
Accurate prediction of the spatial evolution of turbulent wake flows under pressure gradient conditions is required in some engineering applications such as the design of high-lift devices and wind farms over topography. In this paper, we aim to develop an analytical model to predict the evolution of a turbulent planar wake under an arbitrary pressure gradient condition. The model is based on the cross-stream integration of the streamwise momentum equation and uses the self-similarity of the mean flow. We have also made an experimentally supported assumption that the ratio of the maximum velocity deficit to the wake width is independent of the imposed pressure gradient. The asymptotic response of the wake to the pressure gradient is also investigated. After its derivation, the model is successfully validated against experimental data by comparing the evolution of the wake width and maximum velocity deficit. The inputs of the model are the imposed pressure gradient and the wake width under zero pressure gradient. The model does not require any parameter tuning and is deemed to be practical, computationally fast, accurate enough, and therefore useful for the scientific and engineering communities.
Last year marked the thirtieth anniversary of the so-called Historikerstreit (historians’ quarrel), as well as the twentieth anniversary of the lively debate sparked by the publication in 1996 of Daniel J. Goldhagen's Hitler's Willing Executioners: Ordinary Germans and the Holocaust. To mark the occasion, Central European History (CEH) has invited a group of seven specialists from Australia, Germany, Great Britain, and the United States to comment on the nature, stakes, and legacies of the two controversies, which attracted a great deal of both scholarly and popular attention at the time. To set the stage, the following introduction provides a brief overview of the two debates, followed by some personal reflections.