Analyse numérique et réduction de réseaux

29 pagesNational audienceL'algorithmique des réseaux euclidiens est un outil fréquemment utilisé en informatique et en mathématiques. Elle repose essentiellement sur la réduction LLL qu'il est donc important de rendre aussi efficace que possible. Une approche initiée par Schnorr consiste à effectuer des calculs approchés pour estimer les orthogonalisations de Gram-Schmidt sous-jacentes. Sans approximations, ces calculs dominent le coût de la réduction. Récemment, des outils classiques d'analyse numérique ont été revisités et améliorés, pour exploiter plus systématiquement l'idée de Schnorr et réduire les coûts. Nous décrivons ces développements, notamment comment l'algorithmique en nombres flottants peut être introduite à plusieurs niveaux dans la réduction

On the relation of Voevodsky's algebraic cobordism to Quillen's K-theory

Quillen's algebraic K-theory is reconstructed via Voevodsky's algebraic cobordism. More precisely, for a ground field k the algebraic cobordism P^1-spectrum MGL of Voevodsky is considered as a commutative P^1-ring spectrum. There is a unique ring morphism MGL^{2*,*}(k)--> Z which sends the class [X]_{MGL} of a smooth projective k-variety X to the Euler characteristic of the structure sheaf of X. Our main result states that there is a canonical grade preserving isomorphism of ring cohomology theories MGL^{*,*}(X,U) \tensor_{MGL^{2*,*}(k)} Z --> K^{TT}_{- *}(X,U) = K'_{- *}(X-U)} on the category of smooth k-varieties, where K^{TT}_* is Thomason-Trobaugh K-theory and K'_* is Quillen's K'-theory. In particular, the left hand side is a ring cohomology theory. Moreover both theories are oriented and the isomorphism above respects the orientations. The result is an algebraic version of a theorem due to Conner and Floyd. That theorem reconstructs complex K-theory via complex cobordism.Comment: LaTeX, 18 pages, uses XY-pi

Staging of nutrition disorders in non-small-cell lung cancer patients : utility of skeletal muscle mass assessment

Background An international consensus proposed in 2011 a definition and classification system for cachexia (CAX), mainly based on weight loss, sarcopenia [skeletal muscle mass (SMM) loss], inflammation, and anorexia. The aim of this study was to stage CAX in non-small-cell lung cancer (NSCLC) patients by using a classification based on the Fearon criteria and supported by quantifiable parameters. Methods This was a cross-sectional and non-interventional multicentre study. SMM was assessed by analysing L3 computed tomography-scan images. Patients completed the anorexia/CAX subscale of the Functional Assessment of Anorexia/Cachexia Therapy, EORTC QLQ-C30 quality of life (QoL) and International Physical Activity Questionnaire (IPAQ). Results Patients were recruited in 56 sites. The analysis population comprised 531 patients, and SMM was assessed in 312 patients. Male patients were 66.5%, with a mean (SD) age of 65.2 (10.0) years, 79.9% were PS 0-1, and the tumour stage was mainly IIIB-IV (87.3%). Overall, 38.7% of patients had CAX, 33.8% pre-CAX, and 0.9% refractory CAX. Molecular tumour profiles were significantly associated with the presence of CAX: 23.9% in EGFR, ALK, ROS1, BRAF, or HER2+ patients, 41.4% in K-RAS+, and 43.2% in patients with no molecular abnormality (P = 0.003). The more advanced the CAX stage, the poorer the scores of functional items of the QoL (P < 0.001) and International Physical Activity Questionnaire (P < 0.001). Sarcopenia was present in 66.7% of CAX and 68.5% of pre-CAX patients. Overall, 43.8% of pre-CAX patients had only sarcopenia with limited weight loss (<= 2%) and no anorexia. Conclusions This is the first study to show the distribution of CAX in a population of NSCLC patients and an association between molecular abnormality in NSCLC and CAX. The original Fearon classification for CAX stages was supported by the associated functional QoL scores and physical activity levels, resulting in a clinically relevant system for detection of early stages of CAX

Factores asociados a mortalidad en la pandemia de influenza H1N1 2009 en Paraguay

La presencia de condiciones médicas pre-existentes se ha asociado con la mortalidadrelacionada al virus de influenza A (H1N1). El objetivo de este estudio fue determinar losfactores asociados a mortalidad en personas con sospecha de infección con influenza A(H1N1) en Paraguay. Los datos clínicos y epidemiológicos fueron obtenidos a través delsistema de vigilancia para la infección por influenza A(H1N1) establecido en el país por elMinisterio de Salud Pública y Bienestar Social a partir del 28 de abril de 2009. Hasta el 30de enero de 2010, fueron notificados a la Dirección General de Vigilancia de la Salud,8303 casos con sospecha de Influenza A (H1N1). Tanto el análisis bivariado como elmultivariado identificaron los siguientes factores de riesgo de mortalidad: obesidad(p=0,022; OR:13,5), embarazo (p&lt;0,001; OR:11,0), Diabetes mellitus (p= 0,006;OR:5,7), enfermedad cardiovascular (p=0,002; OR: 4,6), sexo masculino (p &lt;0,0001,OR: 3,0), edad mayor a 60 años (p =0,008; OR: 2,9) y no haber sido vacunado contra elvirus de influenza estacional en el periodo 2009 (p&lt;0,023; OR: 2,6). El embarazo comofactor de riesgo de mortalidad ya había sido observado en las otras pandemias; no así laobesidad, la cual recién en la última pandemia, ha sido relacionada, por varios países,con complicaciones graves de infección por el virus A (H1N1). Esta asociación amerita eldesarrollo de investigaciones que permitan un mejor abordaje promocional, preventivo yterapéutico de las personas con obesidad

Embarazo como factor de riesgo de hospitalización y muerte en la pandemia por influenza A (H1N1) en Paraguay

La influenza A (H1N1) se ha identificado como la causa de epidemia de Infección Respiratoria Aguda en Paraguay y en el mundo. Se analizaron los factores de riesgo asociados a la morbimortalidad en embarazadas con sospecha de infección por H1N1 notificadas a la Dirección General de Vigilancia de la Salud (DGVS) del MSPBS durante los primeros cuatro meses de la pandemia, en comparación con mujeres en edad fértil no embarazadas con sospecha de infección por H1N1. A partir del 28 de abril de 2009, la DGVS comenzó sistemáticamente la vigilancia de H1N1 en todas sus unidades notificadoras, siendo la notificación inmediata y por planilla individual basándose la notificación en la definición de casos confirmado establecidas por el país. Hasta el 25 de agosto del 2009 fueron notificadas 2268 mujeres con sospecha de H1N1, de las cuales 1120 tenían entre 15 a 40 años, y de ellas 117 estaban embarazadas. El 68% (79/117) de las embarazadas requirió hospitalización y la mortalidad fue de 21% (25/117), mientras que en grupo de las no embarazadas el 21% se hospitalizó (288 /1003) y la mortalidad fue de 1,5% (16/1003). Todos los casos fallecidos desarrollaron Infección Respiratoria Aguda Grave caracterizado por un síndrome de distrés respiratorio que en algunos casos requirieron asistencia respiratoria mecánica (ARM). Ninguna de las embarazadas refirió antecedente de co-morbilidad. El 22% (26/117) de las embarazadas y 2,9% (30/1003) de las no embarazadas recibieron Oseltamivir como tratamiento. Se evidencian que la infección produce alta morbimortalidad en embarazadas en comparación con mujeres del mismo grupo de edad, los cuales apoyan la recomendación de un tratamiento antiviral precoz en gestantes, así como un seguimiento clínico cercano

A proof of the Grothendieck-Serre conjecture on principal bundles over regular local rings containing infinite fields

Let R be a regular local ring, containing an infinite field. Let G be a reductive group scheme over R. We prove that a principal G-bundle over R is trivial, if it is trivial over the fraction field of R.Comment: Section "Formal loops and affine Grassmannians" is removed as this is now covered in arXiv:1308.3078. Exposition is improved and slightly restructured. Some minor correction

The HLA class II allele DRB1*1501 is over-represented in patients with idiopathic pulmonary fibrosis

Background: Idiopathic pulmonary fibrosis (IPF) is a progressive and medically refractory lung disease with a grim prognosis. Although the etiology of IPF remains perplexing, abnormal adaptive immune responses are evident in many afflicted patients. We hypothesized that perturbations of human leukocyte antigen (HLA) allele frequencies, which are often seen among patients with immunologic diseases, may also be present in IPF patients. Methods/Principal Findings: HLA alleles were determined in subpopulations of IPF and normal subjects using molecular typing methods. HLA-DRB1*15 was over-represented in a discovery cohort of 79 Caucasian IPF subjects who had lung transplantations at the University of Pittsburgh (36.7%) compared to normal reference populations. These findings were prospectively replicated in a validation cohort of 196 additional IPF subjects from four other U.S. medical centers that included both ambulatory patients and lung transplantation recipients. High-resolution typing was used to further define specific HLA-DRB1*15 alleles. DRB1*1501 prevalence in IPF subjects was similar among the 143 ambulatory patients and 132 transplant recipients (31.5% and 34.8%, respectively, p = 0.55). The aggregate prevalence of DRB1*1501 in IPF patients was significantly greater than among 285 healthy controls (33.1% vs. 20.0%, respectively, OR 2.0; 95%CI 1.3-2.9, p = 0.0004). IPF patients with DRB1*1501 (n = 91) tended to have decreased diffusing capacities for carbon monoxide (DLCO) compared to the 184 disease subjects who lacked this allele (37.8±1.7% vs. 42.8±1.4%, p = 0.036). Conclusions/Significance: DRB1*1501 is more prevalent among IPF patients than normal subjects, and may be associated with greater impairment of gas exchange. These data are novel evidence that immunogenetic processes can play a role in the susceptibility to and/or manifestations of IPF. Findings here of a disease association at the HLA-DR locus have broad pathogenic implications, illustrate a specific chromosomal area for incremental, targeted genomic study, and may identify a distinct clinical phenotype among patients with this enigmatic, morbid lung disease

Assessing the uncertainties of model estimates of primary productivity in the tropical Pacific Ocean

Author Posting. © Elsevier B.V., 2009. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Journal of Marine Systems 76 (2009): 113-133, doi:10.1016/j.jmarsys.2008.05.010.Depth-integrated primary productivity (PP) estimates obtained from satellite ocean color based models (SatPPMs) and those generated from biogeochemical ocean general circulation models (BOGCMs) represent a key resource for biogeochemical and ecological studies at global as well as regional scales. Calibration and validation of these PP models are not straightforward, however, and comparative studies show large differences between model estimates. The goal of this paper is to compare PP estimates obtained from 30 different models (21 SatPPMs and 9 BOGCMs) to a tropical Pacific PP database consisting of ~1000 14C measurements spanning more than a decade (1983- 1996). Primary findings include: skill varied significantly between models, but performance was not a function of model complexity or type (i.e. SatPPM vs. BOGCM); nearly all models underestimated the observed variance of PP, specifically yielding too few low PP (< 0.2 gC m-2d-2) values; more than half of the total root-mean-squared model-data differences associated with the satellite-based PP models might be accounted for by uncertainties in the input variables and/or the PP data; and the tropical Pacific database captures a broad scale shift from low biomass-normalized productivity in the 1980s to higher biomass-normalized productivity in the 1990s, which was not successfully captured by any of the models. This latter result suggests that interdecadal and global changes will be a significant challenge for both SatPPMs and BOGCMs. Finally, average root-mean-squared differences between in situ PP data on the equator at 140°W and PP estimates from the satellite-based productivity models were 58% lower than analogous values computed in a previous PP model comparison six years ago. The success of these types of comparison exercises is illustrated by the continual modification and improvement of the participating models and the resulting increase in model skill.This research was supported by a grant from the National Aeronautics and Space Agency Ocean Biology and Biogeochemistry program (NNG06GA03G), as well as by numerous other grants to the various participating investigator

Internal standard-based analysis of microarray data2—Analysis of functional associations between HVE-genes

In this work we apply the Internal Standard-based analytical approach that we described in an earlier communication and here we demonstrate experimental results on functional associations among the hypervariably-expressed genes (HVE-genes). Our working assumption was that those genetic components, which initiate the disease, involve HVE-genes for which the level of expression is undistinguishable among healthy individuals and individuals with pathology. We show that analysis of the functional associations of the HVE-genes is indeed suitable to revealing disease-specific differences. We show also that another possible exploit of HVE-genes for characterization of pathological alterations is by using multivariate classification methods. This in turn offers important clues on naturally occurring dynamic processes in the organism and is further used for dynamic discrimination of groups of compared samples. We conclude that our approach can uncover principally new collective differences that cannot be discerned by individual gene analysis