Etude de l'eau par RMN et IRM dans les procédés laitiers

International audienceL'eau, constituant majeur de nombreux produits alimentaires, a une influence déterminante sur les procédés de transformations, les caractéristiques et la stabilité des produits alimentaires. Les techniques RMN et d'imagerie RMN (IRM) qui fournissent des informations sur la teneur et l'état dynamique de l'eau dans les milieux complexes sont particulièrement adaptées pour caractériser les interactions entre le produit et les variables des procédés. L'objectif de ce document est de présenter quelques exemples de travaux de RMN et d'IRM réalisés dans le secteur des produits laitiers

Etude de l'eau par RMN et IRM dans les procédés laitiers

L'eau, constituant majeur de nombreux produits alimentaires, a une influence déterminante sur les procédés de transformations, les caractéristiques et la stabilité des produits alimentaires. Les techniques RMN et d'imagerie RMN (IRM) qui fournissent des informations sur la teneur et l'état dynamique de l'eau dans les milieux complexes sont particulièrement adaptées pour caractériser les interactions entre le produit et les variables des procédés. L'objectif de ce document est de présenter quelques exemples de travaux de RMN et d'IRM réalisés dans le secteur des produits laitiers

Minority ion current drive and sensitivity of relative positioning of cyclotron resonance layer and inversion radius on sawtooth control

SIGLEAvailable from British Library Document Supply Centre- DSC:4672.2625(JET-R--93/06) / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Minority ion current drive and sensitivity of relative positioning of cyclotron resonance layer and inversion radius on sawtooth control

SIGLEAvailable from British Library Document Supply Centre- DSC:4672.2625(JET-R--93/06) / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Stationary Bragg reflection of laser light in inhomogeneous absorbing plasmas inside inertial confinement fusion Hohlraums

International audienceLaser-produced plasma in inertial confinement fusion (ICF) Hohlraums are marked with density non-uniformity whose length scale can go down to micrometers. This scale is of the order of the laser wavelength. The WKB approximation, which is classically used in radiation-hydrodynamic codes to compute the laser trajectory, cannot correctly take into account such small-scale inhomogeneity of the plasma. Going beyond this approximation, we predict a novel mechanism for the laser reflection. We show that an electromagnetic plane wave with wave number k resonates with the kB=2 k Fourier component of a multimode perturbation of the background density and generates a reflected wave. It is the first time that this reflection is considered for stationary inhomogeneous ICF plasmas, and the energy absorption is taken into account. This mechanism, which is a form of Bragg reflection, can occur away from the critical surface and generate a drift of the location of the laser absorption. Furthermore, this absorption will be periodically modulated with a kB wave number. The stationary Bragg reflection can explain ongoing discrepancies between experimental and numerical data about laser trajectory and absorption in ICF Hohlraums

Sexualidade e gravidez na adolescência entre jovens de camadas médias do Rio de Janeiro, Brasil Middle-class teenage sexuality and pregnancy in Rio de Janeiro, Brazil

Aborda-se a gravidez na adolescência entre jovens de camadas médias, prisma pouco estudado no Brasil. Realizou-se um estudo qualitativo sócio-antropológico com 14 famílias do Rio de Janeiro, Brasil, cujos filhos permaneciam solteiros e residindo com os pais, após o nascimento da criança. Foram realizadas 25 entrevistas em profundidade com 6 rapazes e 7 moças entre 18 e 24 anos e seus pais (11 mães e 1 pai), para avaliação retrospectiva da gravidez e de seus impactos na trajetória juvenil e familiar. Três aspectos são analisados: as dificuldades de internalização da norma contraceptiva; a descoberta tardia da gravidez e a tomada de decisão &shy; aborto ou reprodução &shy; pelos jovens e seus pais. O estudo permitiu configurar a gravidez na adolescência como um evento contingente ao processo de construção da autonomia pessoal em curso nessa fase da vida, no qual a sexualidade tem grande relevância. Conclui-se que o fenômeno precisa ser compreendido em um contexto histórico e cultural específico, distinto de sua ocorrência décadas atrás, pois está marcado pelas regras que organizam o processo de individualização juvenil na contemporaneidade.<br>The subject of this paper is teenage pregnancy among middle-class youth, a topic not sufficiently studied in Brazil. The paper is based on a qualitative, socio-anthropological study of 14 middle-class families in Rio de Janeiro, Brazil, whose children have remained single, living with their parents after the child's birth. A total of 25 in-depth interviews were conducted with 6 young men and 7 young women, ages 18 to 24, and their parents (11 mothers, one father), to examine the event in retrospect and its impact on these young people and their families. Three aspects are analyzed: difficulties young people face in internalizing contraception as a norm; late discovery of pregnancy; and how the decision to either have an abortion or give birth is made by young people and their parents. This research allows seeing teenage pregnancy as an event that hinges on the process of constructing a young person's autonomy, in which sexuality plays a prominent role. Concluding, the phenomenon should be analyzed in a specific historical and cultural context, with changes over the decades in the rules underlying the process of individualization among young people