343 research outputs found

    On a Kelvin-Voigt Viscoelastic Wave Equation with Strong Delay

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    An initial-boundary value problem for a viscoelastic wave equation subject to a strong time-localized delay in a Kelvin & Voigt-type material law is considered. Transforming the equation to an abstract Cauchy problem on the extended phase space, a global well-posedness theory is established using the operator semigroup theory both in Sobolev-valued C0C^{0}- and BV-spaces. Under appropriate assumptions on the coefficients, a global exponential decay rate is obtained and the stability region in the parameter space is further explored using the Lyapunov's indirect method. The singular limit τ→0\tau \to 0 is further studied with the aid of the energy method. Finally, a numerical example from a real-world application in biomechanics is presented.Comment: 34 pages, 4 figures, 1 set of Matlab code

    Motivic Serre invariants, ramification, and the analytic Milnor fiber

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    We show how formal and rigid geometry can be used in the theory of complex singularities, and in particular in the study of the Milnor fibration and the motivic zeta function. We introduce the so-called analytic Milnor fiber associated to the germ of a morphism f from a smooth complex algebraic variety X to the affine line. This analytic Milnor fiber is a smooth rigid variety over the field of Laurent series C((t)). Its etale cohomology coincides with the singular cohomology of the classical topological Milnor fiber of f; the monodromy transformation is given by the Galois action. Moreover, the points on the analytic Milnor fiber are closely related to the motivic zeta function of f, and the arc space of X. We show how the motivic zeta function can be recovered as some kind of Weil zeta function of the formal completion of X along the special fiber of f, and we establish a corresponding Grothendieck trace formula, which relates, in particular, the rational points on the analytic Milnor fiber over finite extensions of C((t)), to the Galois action on its etale cohomology. The general observation is that the arithmetic properties of the analytic Milnor fiber reflect the structure of the singularity of the germ f.Comment: Some minor errors corrected. The original publication is available at http://www.springerlink.co

    Focal autoimmune pancreatitis

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    A 70-year-old man was referred for evaluation of mild epigastric discomfort with tiredness. He had no particular medical history and admitted drinking two glasses of wine a day. Biology showed a small increase in CRP and pancreatic enzymes (lipases and amylases)

    Modélisation micromécanique de l'effet de taille de grains sur le comportement mécanique de matériaux biphasés viscoplastiques

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    Les méthodes d'homogénéisation basées sur le problème de l'inclusion d'Eshelby (1957), tiennent compte du comportement local, de la fraction volumique et de la morphologie des différents constituants du matériau mais souffrent d'une absence de description de longueurs internes (taille de grain par exemple). Cet article propose une nouvelle approche micromécanique basée sur une représentation du grain par une inclusion constituée d'une zone intérieure sphérique plastiquement uniforme entourée d'une couche extérieure sphérique, épousant le joint de grain, d'épaisseur donnée et de fraction volumique dépendant par construction de la taille de grain. L'ensemble est noyé dans un milieu homogène dont les propriétés dépendent des équations constitutives de l'intérieur et de la couche de l'inclusion et de leurs fractions volumiques respectives. La couche dans laquelle évolue à la fois des dislocations géométriquement nécessaires et des dislocations stockées, représente la zone affectée par le gradient de déformation plastique entre l'inclusion et le milieu homogène

    Constructible motivic functions and motivic integration

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    We introduce a direct image formalism for constructible motivic functions. One deduces a very general version of motivic integration for which a change of variables theorem is proved. These constructions are generalized to the relative framework, in which we develop a relative version of motivic integration. These results have been announced in math.AG/0403349 and math.AG/0403350. Main results and statements unchanged. Many minor slips corrected and some details added.Comment: Final versio

    Etiology of Bacterial Meningitis Among Children <5 Years Old in CĂ´te d'Ivoire: Findings of Hospital-based Surveillance Before and After Pneumococcal Conjugate Vaccine Introduction.

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    BACKGROUND: Bacterial meningitis remains a major disease affecting children in CĂ´te d'Ivoire. Thus, with support from the World Health Organization (WHO), CĂ´te d'Ivoire has implemented pediatric bacterial meningitis (PBM) surveillance at 2 sentinel hospitals in Abidjan, targeting the main causes of PBM: Streptococcus pneumoniae (pneumococcus), Haemophilus influenzae, and Neisseria meningitidis (meningococcus). Herein we describe the epidemiological characteristics of PBM observed in CĂ´te d'Ivoire during 2010-2016. METHODS: Cerebrospinal fluid (CSF) was collected from children aged <5 years admitted to the Abobo General Hospital or University Hospital Center Yopougon with suspected meningitis. Microbiology and polymerase chain reaction (PCR) techniques were used to detect the presence of pathogens in CSF. Where possible, serotyping/grouping was performed to determine the specific causative agents. RESULTS: Overall, 2762 cases of suspected meningitis were reported, with CSF from 39.2% (1083/2762) of patients analyzed at the WHO regional reference laboratory in The Gambia. In total, 82 (3.0% [82/2762]) CSF samples were positive for bacterial meningitis. Pneumococcus was the main pathogen responsible for PBM, accounting for 69.5% (52/82) of positive cases. Pneumococcal conjugate vaccine serotypes 5, 18C, 19F, and 6A/B were identified post-vaccine introduction. Emergence of H. influenzae nontypeable meningitis was observed after H. influenzae type b vaccine introduction. CONCLUSIONS: Despite widespread use and high coverage of conjugate vaccines, pneumococcal vaccine serotypes and H. influenzae type b remain associated with bacterial meningitis among children aged <5 years in CĂ´te d'Ivoire. This reinforces the need for enhanced surveillance for vaccine-preventable diseases to determine the prevalence of bacterial meningitis and vaccine impact across the country

    The course of traumatic pancreatitis in a patient with pancreas divisum: a case report

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    BACKGROUND: The peculiar anatomy of pancreatic ducts in pancreas divisum (PD) may interfere with the development of acute chronic pancreatitis. In the presented case, PD influenced the evolution of lesions after pancreatic trauma. CASE PRESENTATION: A 38 years old patient refferred to our hospital with recurrent episodes of mild pancreatitis during the last two years. The first episode occurred four months after blunt abdominal trauma. Endoscopic Retrograde Cholangiopancreatography, Magnetic Resonance Imaging of upper abdomen and Magnetic Resonance Cholangiopancreatography disclosed pancreas divisum, changes consistent with chronic pancreatitis in the dorsal pancreatic duct, atrophy in the body and tail of the pancreas and a pseudocyst in the pancreatic head, that was drained endoscopically. CONCLUSION: Pancreas Divisum may interfere with the evolution of posttraumatic changes in the pancreas after blunt abdominal trauma

    Health & Demographic Surveillance System Profile: The Taabo Health and Demographic Surveillance System, CĂ´te d'Ivoire

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    The Taabo Health and Demographic Surveillance System (HDSS) is located in south-central CĂ´te d'Ivoire, approximately 150 km north-west of Abidjan. The Taabo HDSS started surveillance activities in early 2009 and the man-made Lake Taabo is a key eco-epidemiological feature. Since inception, there has been a strong interest in research and integrated control of water-associated diseases such as schistosomiasis and malaria. The Taabo HDSS has generated setting-specific evidence on the impact of targeted interventions against malaria, schistosomiasis and other neglected tropical diseases. The Taabo HDSS consists of a small town, 13 villages and over 100 hamlets. At the end of 2013, a total population of 42 480 inhabitants drawn from 6707 households was under surveillance. Verbal autopsies have been conducted to determine causes of death. Repeated cross-sectional epidemiological surveys on approximately 5-7% of the population and specific, layered-on haematological, parasitological and questionnaire surveys have been conducted. The Taabo HDSS provides a database for surveys, facilitates interdisciplinary research, as well as surveillance, and provides a platform for the evaluation of health interventions. Requests to collaborate and to access data are welcome and should be addressed to the secretariat of the Centre Suisse de Recherches Scientifiques en CĂ´te d'Ivoire: [[email protected]
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