Sleep Apnea Syndrome and Cognition

Obstructive sleep apnea (OSA) is a sleep-related breathing disorder characterized by repetitive episodes of airflow cessation resulting in brief arousals and intermittent hypoxemia. Several studies have documented significant daytime cognitive and behavioral dysfunction that seems to extend beyond that associated with simple sleepiness and that persists in some patients after therapeutic intervention. A still unanswered question is whether cognitive symptoms in OSA are primarily a consequence of sleep fragmentation and hypoxemia, or whether they coexist independently from OSA. Moreover, very little is known about OSA effects on cognitive performances in the elderly in whom an increased prevalence of OSA is present. In this review we will consider recent reports in the association between sleep apnea and cognition, with specific interest in elderly subjects, in whom sleep disturbances and age-related cognitive decline naturally occur. This will allow us to elucidate the behavioral and cognitive functions in OSA patients and to gain insight into age differences in the cognitive impairment. Clinically, these outcomes will aid clinicians in the evaluation of diurnal consequences of OSA and the need to propose early treatment

Evidence of a boundary layer instability at very high Rayleigh number

In 1997, a Rayleigh-B\'enard experiment evidenced a significant increase of the heat transport efficiency for Rayleigh numbers larger than $Ra \sim 10^{12}$ and interpreted this observation as the signature of the Kraichnan's ``Ultime Regime'' of convection. According to Kraichnan's 1962 prediction, the flow boundary layers above the cold and hot plates -in which most of the fluid temperature drop is localized- become unstable for large enough $Ra$ and this instability boosts the heat transport compared to the other turbulent regimes. Using the same convection cell as in the 1997 experiment, we show that the reported heat transport increase is accompanied with enhanced temperature fluctuations of the bottom plate, which was heated at constant power levels. Indeed, for $Ra < 10^{12}$, the bottom plate fluctuations can simply be accounted from those in the bulk of the flow. In particular, they share the same spectral density at low frequencies, as if the bottom plate was following the slow temperature fluctuations of the bulk, modulo a constant temperature drop across the bottom boundary layer. Conversely, to account for the plate's temperature fluctuations at higher $Ra$, we no-longuer can ignore the fluctuations of the temperature drop across the boundary layer. The negative skewness of fluctuations at high $Ra$ supports the picture of a boundary layer instability. These observations provide new evidence that the transition reported in 1997 corresponds to the triggering of the Ultimate Regime of convection.Comment: Submitted for publicatio

An Early Warning Model for EU banks with Detection of the Adverse Selection Effect

We estimate an early warning model of banks’ failure using a panel of 82 EU banks observed between 1991 and 2005. We make two contributions to the literature. Firstly, we construct a distance-to-default indicator and test its predictive power. The tests implemented here are very similar to those realized by Gropp, Vesala and Vulpes (2005), but our time dimension is four years longer and we use a more restrictive definition of banks’ “failure”. This first part of the paper establishes the accuracy of our data and confirms the robustness of distance-to-default as an early indicator of EU banks’ fragility. Our second advance consists in introducing a variable detecting the adverse selection problem that can be caused by rapid growth strategies. A measure of past average growth of assets is shown to be a very significant and powerful predictor of future banks’ difficulties. We discuss the origins and implications of such an effect.failures; early warning systems; CAMEL ratings; distance to default

On the triggering of the Ultimate Regime of convection

Rayleigh-B\'enard cells are one of the simplest systems to explore the laws of natural convection in the highly turbulent limit. However, at very high Rayleigh numbers (Ra > 1E12) and for Prandtl numbers of order one, experiments fall into two categories: some evidence a steep enhancement of the heat transfer while others do not. The origin of this apparent disagreement is presently unexplained. This puzzling situation motivated a systematic study of the triggering of the regime with an enhanced heat transfer, originally named the "Ultimate Regime" of convection. High accuracy heat transfer measurements have been conducted in convection cells with various aspect ratios and different specificities, such as altered boundary conditions or obstacles inserted in the flow. The two control parameters, the Rayleigh and Prandtl numbers have been varied independently to disentangle their relative influence. Among other results, it is found that i) most experiments reaching very high $Ra$ are not in disagreement if small differences in Prandtl numbers are taken into account, ii) the transition is not directly triggered by the large scale circulation present in the cell, iii) the sidewall of the cell have a significant influence on the transition. The characteristics of this Ultimate regime are summarized and compared with R. Kraichnan prediction for the asymptotic regime of convection.Comment: 25 pages, 14 figure

Lacan's Sade: the politics of happiness

This article assesses the contemporary relevance of Sade’s work and thought by returning to Jacques Lacan’s interpretation of it. It is argued that if the Sadean emphasis on sexual freedom has been co-opted by neoliberal capitalism, this is in part thanks to avant-garde intellectuals of the 20th century who approached Sade through a simplistically libidinal reading of Freud. By contrast, the article argues that Lacan’s more sophisticated reading of Freud enables him in turn to situate Sade amidst 18th-century philosophical and political debates regarding, not sexual pleasure or revolutionary desire, but happiness. Lacan shows that Sade was already challenging the modern, and today market-based, notion of a ‘right to happiness’ with the ‘maxim for jouissance’ he asserted in La Philosophie dans le boudoir. This more troubling Sade, it is claimed, opens up the possibility of a perverse ethic distinct from the ‘polymorphous perversity’ characteristic of contemporary consumer culture and its related conceptions of happiness

Avenir des bibliothèques : l\u27exemple des bibliothèques universitaires (L\u27)

L’évolution des bibliothèques est permanente ; du traitement des collections, sanctuarisées, protégées, le métier de bibliothécaire, après s’être emparé des technologies de l’information, est devenu plus technique ; il doit aujourd’hui se tourner vers un public plus exigeant, plus inconstant, aux attentes plus imprévisibles et plus diverses. Depuis le vote de la loi relative aux libertés et responsabilités des universités, dite loi LRU, en août 2007, et le passage aux responsabilités et compétences élargies (RCE), les missions, la place de la bibliothèque au sein de la communauté académique ne vont plus de soi. Cet ouvrage s’intéresse donc particulièrement aux bibliothèques universitaires ; il installe l’usager, le lecteur, l’étudiant au centre des réflexions ; il traite des usages des étudiants, du devenir des collections, du rôle des personnels, de la politique de services aux publics, des indicateurs appropriés et conclut par une vision prospective et stratégique de la bibliothèque. Au-delà des personnels des bibliothèques universitaires, cet essai s’adresse à tous les directeurs et professionnels, quel que soit le type d’établissement ; il nous interroge sur le devenir de nos professions et sur la plus-value apportée à la communauté nationale ; il intéressera à ce titre un lectorat plus large, soucieux de comprendre la place qu’occupe aujourd’hui la bibliothèque dans la construction du savoir. Coordonné par Florence Roche et Frédéric Saby, conservateurs des bibliothèques au SICD2 de Grenoble, ce volume réunit les contributions de conservateurs, d\u27un maître de conférences et d\u27un sociologue

Bleeding management in remote environment: the use of fresh whole blood transfusion and lyophilised plasma

To mitigate medical risks in remote environments, the authors have implemented an innovative integrated medical support solution for bleeding management on board ships since 2013. Fresh whole blood transfusion (FWBT) and lyophilised plasma were put in place to address life threatening haemorrhages in maritime operations in the Arctic and Antarctica. The authors are illustrating the bleeding risks with an actual case occurring in Antarctica prior to the implementation of these procedures. They are presenting the different steps involved in the complex process of FWBT, from blood donors’ qualifications to actual transfusions. The pros and cons of blood transfusion in extreme remote environment are discussed, including the training of health care professionals, equipment requirements, legal and ethical issues, decision making in complex blood group matching, medical benefits and risks.

Intrapulmonary percussive ventilation superimposed on spontaneous breathing: a physiological study in patients at risk for extubation failure

Purpose: Intrapulmonary percussive ventilation (IPV) is a high-frequency ventilation modality that can be superimposed on spontaneous breathing. IPV may diminish respiratory muscle loading and help to mobilize secretions. The aim of this prospective study was to assess the short-term effects of IPV in patients at high risk for extubation failure who were receiving preventive non-invasive ventilation (NIV) after extubation. Methods: Respiratory rate, work of breathing, and gas exchange were evaluated in 17 extubated patients during 20min of IPV and 20min of NIV delivered via a facial mask, separated by periods of spontaneous breathing. The pressure-support level during NIV was adjusted until tidal volume reached 6-8ml/kg and positive end-expiratory pressure (PEEP) 4-5cmH2O. For IPV, the pressurisation frequency was set at 250cycles/min and driving pressure at 1.2bar. The pressure-time product of the diaphragm (PTPdi/min) was measured using an oesophageal and gastric double-balloon catheter. Results: Transdiaphragmatic pressure and PTPdi/min improved significantly (p<0.01), from a median [25th-75th percentiles] of 264 [190-300] to 192 [152-221]cmH2Os/min with IPV and from 273 [212-397] to 176 [120-216]cmH2Os/min with NIV. Respiratory rate decreased significantly from 23 [19-27] to 22 [17-24] breaths/min for IPV and from 25 [19-28] to 20 [18-22] breaths/min for NIV (p<0.01). Mean PaCO2 decreased after NIV (from 46 [42-48] to 41 [36-42]mmHg, p<0.01) but not after IPV. There was no noticeable effect on oxygenation. Conclusions: IPV is an interesting alternative to NIV in patients at risk for post-extubation respiratory failure. Both NIV and IPV diminished the respiratory rate and work of breathing, but IPV was less effective in improving alveolar ventilatio