Amélioration de la précision et réduction des zones masquéees de capteurs à ultrasons grâce à l'utilistation de séquences complémentaires de Golay

Les systèmes sensoriels basés sur les capteurs à ultrasons présentent certaines contraintes qui ont tendance à réduire leur performance. Parmi les problèmes typiques, nous pouvons citer la faible précision des mesures et l'existence à l'avant des capteurs de zones masquées, zones où les réflecteurs ne peuvent pas être détectés si les capteurs sont utilisés comme émetteurs et récepteurs. Dans le but d'améliorer la précision des mesures réalisées par ces capteurs, les émissions sont le plus souvent codées par des séquences binaires. Les distances peuvent être alors déterminées en faisant appel à des techniques de corrélation. Dans ce cadre, ce travail présente les résultats obtenus lors de l'utilisation de séquences complémentaires de Golay, lesquelles permettent d'augmenter de manière significative la précision obtenue à partir d'un capteur à ultrasons isolé. Elles permettent également d'éliminer les zones masquées précédemment citées grâce à leurs caractéristiques d'autocorrélation. Ces deux fonctions seront très intéressantes dans l'optique d'une utilisation de capteurs à ultrasons dans le cadre d'associations sensorielles plus complexes.Sensorial systems based on ultrasonic transducers present some constraints, which reduce their performances. Typical problems are low precision in measurements, and the existence of a blind zone in front of transducers, where reflectors can not be detected if transducers are used as emitters and receivers. In order to improve the precision achieved by these transducers, binary sequences are often used to code the emission, so afterwards, distances can be determined using correlation techniques. The usage of Golay complementary sequences allows to increase remarkably the precision obtained by an isolated ultrasonic transducer. Also, it permits to eliminate the mentioned blind zone, thanks to their auto-correlation characteristics. These two features are very interesting in order to use ultrasonic transducers in more complex sensorial associations

Guidelines for treatment of umbilical and epigastric hernias from the European Hernia Society and Americas Hernia Society.

Background: Umbilical and epigastric hernia repairs are frequently performed surgical procedures with an expected low complication rate. Nevertheless, the optimal method of repair with best short- and long-term outcomes remains debatable. The aim was to develop guidelines for the treatment of umbilical and epigastric hernias. Methods: The guideline group consisted of surgeons from Europe and North America including members from the European Hernia Society and the Americas Hernia Society. The Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach, the Scottish Intercollegiate Guidelines Network (SIGN) critical appraisal checklists, and the Appraisal of Guidelines for Research and Evaluation (AGREE) instrument were used. A systematic literature search was done on 1 May 2018, and updated on 1 February 2019. Results: Literature reporting specifically on umbilical and epigastric hernias was limited in quantity and quality, resulting in a majority of the recommendations being graded as weak, based on low-quality evidence. The main recommendation was to use mesh for repair of umbilical and epigastric hernias to reduce the recurrence rate. Most umbilical and epigastric hernias may be repaired by an open approach with a preperitoneal flat mesh. A laparoscopic approach may be considered if the hernia defect is large, or if the patient has an increased risk of wound morbidity. Conclusion: This is the first European and American guideline on the treatment of umbilical and epigastric hernias. It is recommended that symptomatic umbilical and epigastric hernias are repaired by an open approach with a preperitoneal flat mesh.post-print1636 K

EHS and AHS guidelines for treatment of primary ventral hernias in rare locations or special circumstances

Background Rare locations of hernias, as well as primary ventral hernias under certain circumstances (cirrhosis, dialysis, rectus diastasis, subsequent pregnancy), might be technically challenging. The aim was to identify situations where the treatment strategy might deviate from routine management. Methods The guideline group consisted of surgeons from the European and Americas Hernia Societies. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach was used in formulating the recommendations. The Scottish Intercollegiate Guidelines Network (SIGN) critical appraisal checklists were used to evaluate the quality of full-text papers. A systematic literature search was performed on 1 May 2018 and updated 1 February 2019. The Appraisal of Guidelines for Research and Evaluation (AGREE) instrument was followed. Results Literature was limited in quantity and quality. A majority of the recommendations were graded as weak, based on low quality of evidence. In patients with cirrhosis or on dialysis, a preperitoneal mesh repair is suggested. Subsequent pregnancy is a risk factor for recurrence. Repair should be postponed until after the last pregnancy. For patients with a concomitant rectus diastasis or those with a Spigelian or lumbar hernia, no recommendation could be made for treatment strategy owing to lack of evidence. Conclusion This is the first European and American guideline on the treatment of umbilical and epigastric hernias in patients with special conditions, including Spigelian and lumbar hernias. All recommendations were weak owing to a lack of evidence. Further studies are needed on patients with rectus diastasis, Spigelian and lumbar hernias

Cosmological models in scalar tensor theories of gravity and observations: a class of general solutions

We consider cosmological models in scalar tensor theories of gravity that describe an accelerating universe, and we study a family of inverse power law potentials, for which exact solutions of the Einstein equations are known. We also compare theoretical predictions of our models with observations. For this we use the following data: the publicly available catalogs of type Ia supernovae and high redshift Gamma Ray Bursts, the parameters of large scale structure determined by the 2-degree Field Galaxy Redshift Survey (2dFGRS), and measurements of cosmological distances based on the Sunyaev-Zel'dovich effect, among others.Comment: 26 pages,23 figures, accepted for publication in A&