Differential Geometry applied to Acoustics : Non Linear Propagation in Reissner Beams

Although acoustics is one of the disciplines of mechanics, its "geometrization" is still limited to a few areas. As shown in the work on nonlinear propagation in Reissner beams, it seems that an interpretation of the theories of acoustics through the concepts of differential geometry can help to address the non-linear phenomena in their intrinsic qualities. This results in a field of research aimed at establishing and solving dynamic models purged of any artificial nonlinearity by taking advantage of symmetry properties underlying the use of Lie groups. The geometric constructions needed for reduction are presented in the context of the "covariant" approach.Comment: Submitted to GSI2013 - Geometric Science of Informatio

Epidémiologie clinique des affections neurologiques dans la ville de Douala

Introduction: La morbi-mortalité des affections neurologiques est sans cesse croissante dans le monde. Elles sont responsables de 6,8 millions de décès par an et représentent la première cause du handicap acquis non traumatique de l’adulte. La connaissance de l’épidémiologie des maladies neurologiques est nécessaire pour l’affectation des ressources. Le but de cette étude était de décrire les caractéristiques épidémiologiques des maladies neurologiques dans les hôpitaux de première et deuxième catégorie de la ville de Douala.Méthodologie: Il s’agissait d’une étude transversale sur 24 mois, du 1er mai 2012 au 30 Avril 2014 menée dans le service et l’unité de Neurologie des Hôpitaux Laquintinie et Général de Douala. Était inclus dans l’étude, tout patient âgé de plus de 15 ans hospitalisé ou vu en consultation par un neurologue pour trouble neurologique. Le handicap moteur était apprécié à l’aide de la cotation musculaire de la Medical Research Council (MRC) sur 5 points : handicap sévère pour une force motrice comprise entre 0 et 2, handicap modéré pour une force motrice allant de 3 à 4 et pas de handicap pour une force motrice de 5. Notre échantillonnage était consécutif et exhaustif.Résultats: Au total, 3976 patients étaient inclus avec 55,3% de femmes; l’âge moyen était de 49 ±17,9 ans. Les principaux motifs de consultation étaient le déficit moteur d’un ou de plusieurs membres (17,8%), les céphalées (16,6%), les convulsions (10,05%), les douleurs d’un ou plusieurs membres (9,7%) et l’altération de la conscience (9,4%). Les principales comorbidités étaient l’hypertension artérielle (41%), l’infection au VIH (14,4%), le diabète (11,68%) et l’alcoolisme (10,82%). Les maladies neurologiques étaient dominées par l’accident vasculaire cérébral (30,02%), les céphalées (13,33%), les infections du système nerveux central (11,31%) et l’épilepsie (11,09%). 52,5% des patients hospitalisés présentaient un handicap moteur dont 42,5% étaient classés sévères. La mortalité des maladies neurologiques en hospitalisation était de 19,1%. Les causes présumées de décès étaient l’AVC (55,7%), l’encéphalite et la méningo-encéphalite (17,5%) et les abcès cérébraux (14,5%).Conclusion: Les affections neurologiques dans les hôpitaux de Douala sont dominées par les pathologies vasculaire et infectieuse. Près d’un patient hospitalisé sur cinq décède en hospitalisation tandis que deux patients hospitalisé sur cinq présentent un handicap sévère. Ce travail souligne l’importance de la prévention des affections neuro-vasculaires et neuro-infectieuses dans notre contexte.Mots clés: Épidémiologie, maladies neurologiques, Douala, CamerounEnglish Title: Clinical epidemiology of neurological diseases in the city of DoualaEnglish AbstractBackground: Morbidity and mortality related to neurological disorders are increasing worldwide. They are responsible for about 6,8 million deaths per year and represent the first cause of acquired physical handicap. The main objective of this study was to describe the epidemiological characteristics of neurological diseases in two Referral Hospitals in Douala, Cameroon.Methods: We carried out a cross-sectional hospital based study over a 24 months period from the 1st of May 2012 to the 30st April 2014 in two neurological services at the Douala Laquintinie and General hospitals. Were included in this study, every patient aged above 15 years, hospitalized or seen in consultation for neurological disorders. Physical disability was evaluated using the Medical Research Council (MRC) score (0 to 5): severe for MRC score of 0 to 2, moderate for MRC score of 3 to 4 and no disability for a MRC score of 5.Results: A total of 3976 patients were enrolled with 55.3% been female. The mean age was 49±17. 19 years. 50.1% of patients were hospitalized. The common presenting complaints were motor deficits of one or more limbs (17.8%), headaches (16.6%), seizures (10.05%), other pain on the limbs (9.7%) and altered mental status (9.4%). The leading comorbidities were high blood pressure (41.0%), HIV infection (14.4%), diabetes (11.8%) and alcoholism (10.82%). Neurological diseases were stroke (30.02%), primary headache (13.33%), central nervous infections (11.31%) and epilepsy (11.01%). 52.5% of the in-patients were discharged with physical disability, 42.5% of these was severe. The mortality rate of neurological disease in-inpatients was 19.1% etiologies of death been stroke (55.7%) encephalitis and meningoencephalitis (17.5%) and cerebral abscess (14.5%).Conclusion: Neurovascular and neuroinfectious diseases represent the leading cause of neurological disorder in Douala. One over 5 patients hospitalized with neurological disorder would die while two over five would present a severe handicap. This study highlighted the need for neurovascular and neuroinfectious disease’s prevention in our environment.Keywords: Epidemiology, Neurological Diseases, Douala, Cameroo

International Society of Human and Animal Mycology (ISHAM)-ITS reference DNA barcoding database - The quality controlled standard tool for routine identification of human and animal pathogenic fungi

Human and animal fungal pathogens are a growing threat worldwide leading to emerging infections and creating new risks for established ones. There is a growing need for a rapid and accurate identification of pathogens to enable early diagnosis and targeted antifungal therapy. Morphological and biochemical identification methods are time-consuming and require trained experts. Alternatively, molecular methods, such as DNA barcoding, a powerful and easy tool for rapid monophasic identification, offer a practical approach for species identification and less demanding in terms of taxonomical expertise. However, its wide-spread use is still limited by a lack of quality-controlled reference databases and the evolving recognition and definition of new fungal species/complexes. An international consortium of medical mycology laboratories was formed aiming to establish a quality controlled ITS database under the umbrella of the ISHAM working group on "DNA barcoding of human and animal pathogenic fungi." A new database, containing 2800 ITS sequences representing 421 fungal species, providing the medical community with a freely accessible tool at http://www.isham.org/ and http://its.mycologylab.org/ to rapidly and reliably identify most agents of mycoses, was established. The generated sequences included in the new database were used to evaluate the variation and overall utility of the ITS region for the identification of pathogenic fungi at intra-and interspecies level. The average intraspecies variation ranged from 0 to 2.25%. This highlighted selected pathogenic fungal species, such as the dermatophytes and emerging yeast, for which additional molecular methods/genetic markers are required for their reliable identification from clinical and veterinary specimens. © The Author 2015. Published by Oxford University Press on behalf of The International Society for Human and Animal Mycology