Reversibility of airflow obstruction by hypoglossus nerve stimulation in anesthetized rabbits

Rationale: Anesthesia-induced uncoupling of upper airway dilating and inspiratory pump muscles activation may cause inspiratory flow limitation, thereby mimicking obstructive sleep apnea/hypopnea. Objectives: Determine whether inspiratory flow limitation occurs in spontaneously breathing anesthetized rabbits and whether this can be reversed by direct hypoglossal nerve stimulation and by the application of continuous positive airway pressure. Methods: Ten New Zealand White rabbits were anesthetized, instrumented, and studied supine while breathing spontaneously at ambient pressure or during the application of positive or negative airway pressure. Under each of these conditions, the effect of unilateral or bilateral hypoglossal nerve stimulation was investigated. Measurements: Inspiratory flow and tidal volume were measured together with esophageal pressure and the electromyographic activity of diaphragm, alae nasi, and genioglossus muscles. Main results: Anesthesia caused a marked increase in inspiratory resistance, snoring, and in eight rabbits, inspiratory flow limitation. Hypoglossus nerve stimulation was as effective as continuous positive airway pressure in reversing inspiratory flow limitation and snoring. Its effectiveness increased progressively as airway opening pressure was lowered, reached a maximum at -5 cm H2O, but declined markedly at lower pressures. With negative airway opening pressure, airway collapse eventually occurred during inspiration that could be prevented by hypoglossus nerve stimulation. The recruitment characteristics of hypoglossus nerve fibers was steep, and significant upper airway dilating effects already obtained with stimulus intensities 36 to 60% of maximum. Conclusion: This study supports hypoglossus nerve stimulation as a treatment option for obstructive sleep apnea

Etude des résultats d'exploitation d'unités de pêche artisanale en Martinique

L'étude des résultats d'exploitations de 55 unités de pêche, durant la période de Miquelon (de Décembre à Juin 1986) fait apparaître des résultats économiques certes variables mais, dans l'ensemble, médiocres : sur les 1397 sorties observées, près de la moitié aboutit à un niveau de recette nette de coûts variables négative et un peu plus du quart de ces sorties dégage une recette nette de C.V. compris entre 0 et 499 francs. Sur les 55 unités de pêche étudiées, plus du tiers des patrons de pêcheurs ont un résultat négatif et près de 50 % ont "une part patron" mensualisée inférieure au SMIC (Résumé d'auteur

Analyse de cartes de profondeur pour la navigation active dans un volume image

Nous proposons une méthode de navigation automatique d'un endoscope virtuel à l'intérieur d'un volume image. Cette navigation est basée sur la vision, la décision de déplacement repose sur une perception locale des configurations spatiales sans traitement préalable (segmentation, modélisation) du volume. En effet nous privilégions ici une analyse de l'image -obtenue par lancer de rayons- à partir de sa carte de profondeur. De ce traitement nous obtenons la détection automatique des branchements et une information structurelle sur la scène observée

Monitoring and Pay: An Experiment on Employee Performance under Endogenous Supervision

We present an experimental test of a shirking model where monitoring intensity is endogenous and effort a continuous variable. Wage level, monitoring intensity and consequently the desired enforceable effort level are jointly determined by the maximization problem of the firm. As a result, monitoring and pay should be complements. In our experiment, between and within treatment variation is qualitatively in line with the normative predictions of the model under standard assumptions. Yet, we also find evidence for reciprocal behavior. Our data analysis shows, however, that it does not pay for the employer to solely rely on the reciprocity of employees

Volumetric Segmentation of Pelvic Organs from MRI Acquisitions

In this work we present part of a Pelvis Dynamics Modeling System for pre-surgical assistance in the pelvic organ prolapse disease. In this condition, the most common affected organs are the uterus, the bladder and the rectum. The Magnetic Resonance Imaging (MRI) is the gold standard non-invasive imaging technique to evaluate this condition. The MRI’s acquisitions provide spatial information that is essential to build tri-dimensional (3D) models and run physical simulations that recreate the prolapse. In these acquisitions, the above mentioned organs, present blurred borders and different textures. Therefore, its extraction in not trivial at all. We pose an hybrid semi-automatic segmentation strategy which combines Region Growing (RG) and Active Surfaces in MRI scans to retrieve surface meshes of the organs of interest. We show some real cases, one applying the complete process in detail and the others, providing final results attained by the method which shows high quality segmentations achieved with a low computational cost.Sociedad Argentina de Informática e Investigación Operativ