A new construction of Moufang quadrangles of type E6, E7 and E8

In the classification of Moufang polygons by J. Tits and R. Weiss, the most intricate case is by far the case of the exceptional Moufang quadrangles of type E6, E7 and E8, and in fact, the construction that they present is ad-hoc and lacking a deeper explanation. We will show how tensor products of two composition algebras can be used to construct these Moufang quadrangles in characteristic different from 2. As a byproduct, we will obtain a method to construct any Moufang quadrangle in characteristic different from two from a module for a Jordan algebra

A Neural Network Demand System

URL des Documents de travail : http://centredeconomiesorbonne.univ-paris1.fr/bandeau-haut/documents-de-travail/Documents de Travail du Centre d'Economie de la Sorbonne 2013.81 - ISSN : 1955-611XWe introduce a new type of demand system using a feedforward artificial neural network. The neural network demand system is a flexible system that requires few hypotheses, has no roots in consumer theory but may be used to test it. We use the system to estimate demand elasticities on micro data of household consumption in Canada between 2004 and 2008, and compare the results to those of the quadratic almost ideal demand system.Nous présentons un nouveau type de système complet de demande utilisant un réseau de neurones artificiels. Le système de demande à réseau de neurones est un système flexible nécessitant un minimum d'hypothèses. Sa formulation ne provient pas de la théorie du consommateur, mais il peut être utilisé pour la tester. Nous appliquons ce système à l'estimation d'élasticités de la demande des ménages sur des micro données canadiennes de 2004 à 2008, et comparons les résultats à ceux obtenus à l'aide du système QUAIDS

Exceptional Moufang quadrangles and structurable algebras

In 2000, J. Tits and R. Weiss classified all Moufang spherical buildings of rank two, also known as Moufang polygons. The hardest case in the classification consists of the Moufang quadrangles. They fall into different families, each of which can be described by an appropriate algebraic structure. For the exceptional quadrangles, this description is intricate and involves many different maps that are defined ad hoc and lack a proper explanation. In this paper, we relate these algebraic structures to two other classes of algebraic structures that had already been studied before, namely to Freudenthal triple systems and to structurable algebras. We show that these structures give new insight in the understanding of the corresponding Moufang quadrangles.Comment: 49 page

Response to Tsikas et al. comments on Boelaert et al. Determination of asymmetric and symmetric dimethylarginine in serum from patients with chronic kidney disease: UPLC-MS/MS versus ELISA. Toxins 2016, 8, 149

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Metabolic profiling of human plasma and urine in chronic kidney disease by hydrophilic interaction liquid chromatography coupled with time-of-flight mass spectrometry : a pilot study

A typical characteristic of chronic kidney disease (CKD) is the progressive loss in renal function over a period of months or years with the concomitant accumulation of uremic retention solutes in the body. Known biomarkers for the kidney deterioration, such as serum creatinine or urinary albumin, do not allow effective early detection of CKD, which is essential towards disease management. In this work, a hydrophilic interaction liquid chromatography time-of-flight mass spectrometric (HILIC-TOF MS) platform was optimized allowing the search for novel uremic retention solutes and/or biomarkers of CKD. The HILIC-ESI-MS approach was used for the comparison of urine and plasma samples from CKD patients at stage 3 (n = 20), at stage 5 not yet receiving dialysis (n = 20) and from healthy controls (n = 20). Quality control samples were used to control and ensure the validity of the metabolomics approach. Subsequently the data were treated with the XCMS software for multivariate statistical analysis. In this way, differentiation could be achieved between the measured metabolite profile of the CKD patients versus the healthy controls. The approach allowed the elucidation of a number of metabolites that showed a significant up- and downregulation throughout the different stages of CKD. These compounds are cinnamoylglycine, glycoursodeoxycholic acid, 2-hydroxyethane sulfonate, and pregnenolone sulfate of which the identity was unambiguously confirmed via the use of authentic standards. The latter three are newly identified uremic retention solutes

Impact of a mass vaccination campaign against a meningitis epidemic in a refugee camp.

Serogroup A meningococcus epidemics occurred in refugee populations in Zaire in August 1994. The paper analyses the public health impact of a mass vaccination campaign implemented in a large refugee camp. We compared meningitis incidence rates from 2 similar camps. In Kibumba camp, vaccination was implemented early in the course of the epidemic whilst in the control camp (Katale), vaccination was delayed. At a threshold of 15 cases per 100 000 population per week an immunization campaign was implemented. Attack rates were 94 and 134 per 100,000 in Kibumba and Katale respectively over 2 months. In Kibumba, one week after crossing the threshold, 121,588 doses of vaccine were administered covering 76% of all refugees. Vaccination may have prevented 68 cases (30% of the expected cases). Despite its rapid institution and the high coverage achieved, the vaccination campaign had a limited impact on morbidity due to meningitis. In the early phase in refugee camps, the relative priorities of meningitis vaccination and case management need to be better defined