Analyse et simulation topologiques en géographie, application à l’étude des migrations interrégionales

Le modèle d'Analyse et de Simulation Topologique est à l'analyse de système ce que l'analyse de régression multiple est à l'analyse multivariée. Pour un système de flux ce modèle détermine les gains effectués par tous les noeuds dépendants pour tout changement de flux dans le noeud principal ; il détermine l'importance des diverses lignes de transmission entre les éléments et il permet de connaître la sensibilité d'un élément aux variations de flux sur tout arc du réseau. C'est un modèle qui pourrait s'avérer très utile pour des études d'interdépendance systémique ou pour une recherche sur les lignes de transmissions d'un phénomène de diffusion. C'est une technique très intéressante également pour mesurer l'évolution d'un réseau et connaître les éléments qui ont tendance à être refoulés en marge du système par d'autres qui prennent de l'importance.À titre d'illustration, le modèle a été appliqué à l'étude des migrations de populations en France pour les années 1962-68, dans le cadre des régions de programme.The A.S.T. model, Analyse et Simulation Topologique, does for system analysis what multiple regression does for multivariate analysis. For an origin-destination table this model determines the gains effected by the dependent elements of the System for any change in the independent ; it calculates the transmission links and gains, and it also establishes the sensitivity of any element to fluctuations in any arc of the network. It is a model which should prove of considerable interest for studies of repercussion effects of flow fluctuations, or for the analysis of transmission flows in a diffusion process. It should also prove of value for the study of the evolution of a system to establish which elements are gaining in influence and which are being relegated to the outer fringes.As an illustration, the model was applied to the study of the flow patterns of French migrant populations for the period 1962-68, by planning region

Black-body photon clustering by semi-classical means

If stimulated emission could be turned off then only uncorrelated photons would be emitted from black bodies and the photon counting statistics would be Poissonian. Through the process of stimulated emission, some fraction of the photons emitted from a black body are correlated and thus emitted in clusters. This photon clustering can be calculated by semi-classical means. The corresponding results are in agreement with quantum theory.Comment: 10 pages, 2 figures, 1 table. Added proof that stimulated-emission produced photon clustering at the source leads to the Hanbury Brown and Twiss effect without invoking photon-photon interference. Fixed unit mistakes in the left hand side of Eqs (4), (6), (7), and (9

Oxidation behaviour of unirradiated sintered UO2 pellets and powder at different oxygen partial pressures, above 350°C

International audienceThe oxidation of sintered UO2 pellets and powder into U3O8 has been studied by thermogravimetry at 370°C, under controlled oxygen partial pressures (PO2 ranging from 2-40 kPa). Sigmoidal curves of oxidation weight gain were measured for both pellet and powder test samples. The rate of oxidation increased as the oxygen partial pressure increased. It has been shown, by simultaneous TG-DSC, that the reaction proceeds in a pseudo steady state. An experimental methodology based on temperature or PO2 jumps has shown that the assumption of a rate-limiting step is validated, and a mean value of activation energy for the formation of U3O8 of 103 kJ.mol-1 was estimated

Estudo epidemiológico de sintomas osteomusculares em cirurgiões-dentistas do Distrito Federal

O Objetivo foi verificar a distribuição de sintomas osteomusculares nos cirurgiõesdentistas ativos do Distrito Federal. Materiais e métodos: Estudo transversal realizado com cirurgiões-dentistas, no qual verificou-se a ocorrência de sintomas osteomusculares em 12 regiões anatômicas, por meio do questionário Nórdico. Tal questionário foi modificado para permitir a medida de variáveis demográficas, ocupacionais e hábitos e estilo de vida. Os dados foram analisados pela estatística descritiva, com prevalência, média e desvio-padrão no Statistical Package for Social Science (SPSS) versão 17.0 para Windows, com nível de significância de p≤0,05. Resultados: Participaram do estudo 100 cirurgiões-dentistas com média de idade de 34,8 ± 8,2 anos, sendo 63 do sexo feminino. O tempo de atuação na profissão foi de 11,6 ± 7,7 anos. Da amostra 52 sujeitos eram praticantes de atividade física, 20 executavam outra ocupação profissional e 35 colaboravam com as atividades domésticas. O uso do microcomputador foi relatado por 75 participantes e a grande maioria (91%) referiu algum quadro álgico relacionado ao trabalho. As regiões de maior prevalência de dor foram cervical (79%), lombar (73%), seguido de ombro (70%) e punho/mão (65%). Conclusão: o cirurgião-dentista pertence a uma área profissional predisposta a desenvolver complicações osteomusculares. As posturas viciosas e os instrumentos de trabalho podem ser fatores de risco para o aparecimento de dores, principalmente em membros superiores e coluna vertebral

Rapidly Prepared Nanocellulose Hybrids as Gas Barrier, Flame Retardant, and Energy Storage Materials

Cellulose nanofibril (CNF) hybrid materials show great promise as sustainable alternatives to oil-based plastics owing to their abundance and renewability. Nonetheless, despite the enormous success achieved in preparing CNF hybrids at the laboratory scale, feasible implementation of these materials remains a major challenge due to the time-consuming and energy-intensive extraction and processing of CNFs. Here, we describe a scalable materials processing platform for rapid preparation (<10 min) of homogeneously distributed functional CNF−gibbsite and CNF−graphite hybrids through a pH-responsive self-assembly mechanism, followed by their application in gas barrier, flame retardancy, and energy storage materials. Incorporation of 5 wt % gibbsite results in strong, transparent, and oxygen barrier CNF−gibbsite hybrid films in 9 min. Increasing the gibbsite content to 20 wt % affords them self-extinguishing properties, while further lowering their dewatering time to 5 min. The strategy described herein also allows for the preparation of freestanding CNF−graphite hybrids (90 wt % graphite) that match the energy storage performance (330 mA h/g at low cycling rates) and processing speed (3 min dewatering) of commercial graphite anodes. Furthermore, these ecofriendly electrodes can be fully recycled, reformed, and reused while maintaining their initial performance. Overall, this versatile concept combines a green outlook with high processing speed and material performance, paving the way toward scalable processing of advanced ecofriendly hybrid material

Nanocellulose and PEDOT:PSS composites and their applications

The need for achieving sustainable technologies has encouraged research on renewable and biodegradable materials for novel products that are clean, green, and environmentally friendly. Nanocellulose (NC) has many attractive properties such as high mechanical strength and flexibility, large specific surface area, in addition to possessing good wet stability and resistance to tough chemical environments. NC has also been shown to easily integrate with other materials to form composites. By combining it with conductive and electroactive materials, many of the advantageous properties of NC can be transferred to the resulting composites. Conductive polymers, in particular poly(3,4-ethylenedioxythiophene:poly(styrene sulfonate) (PEDOT:PSS), have been successfully combined with cellulose derivatives where suspensions of NC particles and colloids of PEDOT:PSS are made to interact at a molecular level. Alternatively, different polymerization techniques have been used to coat the cellulose fibrils. When processed in liquid form, the resulting mixture can be used as a conductive ink. This review outlines the preparation of NC/PEDOT:PSS composites and their fabrication in the form of electronic nanopapers, filaments, and conductive aerogels. We also discuss the molecular interaction between NC and PEDOT:PSS and the factors that affect the bonding properties. Finally, we address their potential applications in energy storage and harvesting, sensors, actuators, and bioelectronics

The 32 kDa subunit of replication protein A (RPA) participates in the DNA replication of Mung bean yellow mosaic India virus (MYMIV) by interacting with the viral Rep protein

Mung bean yellow mosaic India virus (MYMIV) is a member of genus begomoviridae and its genome comprises of bipartite (two components, namely DNA-A and DNA-B), single-stranded, circular DNA of about 2.7 kb. During rolling circle replication (RCR) of the DNA, the stability of the genome and maintenance of the stem–loop structure of the replication origin is crucial. Hence the role of host single-stranded DNA-binding protein, Replication protein A (RPA), in the RCR of MYMIV was examined. Two RPA subunits, namely the RPA70 kDa and RPA32 kDa, were isolated from pea and their roles were validated in a yeast system in which MYMIV DNA replication has been modelled. Here, we present evidences that only the RPA32 kDa subunit directly interacted with the carboxy terminus of MYMIV-Rep both in vitro as well as in yeast two-hybrid system. RPA32 modulated the functions of Rep by enhancing its ATPase and down regulating its nicking and closing activities. The possible role of these modulations in the context of viral DNA replication has been discussed. Finally, we showed the positive involvement of RPA32 in transient replication of the plasmid DNA bearing MYMIV replication origin using an in planta based assay

Difficult intubation and extubation in adult anaesthesia.

To provide an update to French guidelines about "Difficult intubation and extubation in adult anaesthesia 2006". A consensus committee of 13 experts was convened. A formal conflict-of-interest (COI) policy was developed at the onset of the process and enforced throughout. The entire guidelines process was conducted independent of any industry funding. The authors were advised to follow the principles of the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system to guide assessment of quality of evidence. The potential drawbacks of making strong recommendations in the presence of low-quality evidence were emphasized. Few recommendations were ungraded. The panel focused on 6 questions: 1) Why must oxygen desaturation be avoided during intubation and what preoxygenation and oxygenation techniques should be used to prevent it? 2) Should videolaryngoscopes be used instead of standard laryngoscopy with or without a long stylet to achieve a better success rate of intubation after the first attempt during anticipated difficult intubation off fiberoptic intubation? 3) Should TCI or target controlled inhalation anaesthesia (TCIA) be used instead of bolus sedation for airway control in the event of suspected or proven difficulty in a patient spontaneously breathing? 4) What mode of anaesthesia should be performed in patients with difficult intubation criteria and potentially difficult mask ventilation? 5) In surgical patients, what criteria predict difficulties encountered during postoperative tracheal extubation? 6) Should decision trees and algorithms be employed to direct decision-making for the management of difficult intubation, whether foreseen or not? (based on the information from the preceding five issues). Population, intervention, comparison, and outcomes (PICO) questions were reviewed and updated as needed, and evidence profiles were generated. The analysis of the literature and the recommendations were then conducted according to the GRADE <sup>®</sup> methodology. The SFAR Guideline panel provided 13 statements on difficult intubation and extubation in adult anaesthesia. After two rounds of discussion and various amendments, a strong agreement was reached for 99% of recommendations. Of these recommendations, five have a high level of evidence (Grade 1±), 8 have a low level of evidence (Grade 2±). No recommendation was provided for one question. Substantial agreement exists among experts regarding many strong recommendations for the best care of patients with difficult intubation and extubation in adult anaesthesia