Characterization of a double-sided silicon strip detector autoradiography system

The most commonly used technology currently used for autoradiography is storage phosphor screens, which has many benefits such as a large field of view but lacks particle-counting detection of the time and energy of each detected radionuclide decay. A number of alternative designs, using either solid state or scintillator detectors, have been developed to address these issues. The aim of this study is to characterize the imaging performance of one such instrument, a double-sided silicon strip detector (DSSD) system for digital autoradiography. A novel aspect of this work is that the instrument, in contrast to previous prototype systems using the same detector type, provides the ability for user accessible imaging with higher throughput. Studies were performed to compare its spatial resolution to that of storage phosphor screens and test the implementation of multiradionuclide ex vivo imaging in a mouse preclinical animal study

Prevalence and predictors of HIV-related stigma among institutional- and community-based caregivers of orphans and vulnerable children living in five less-wealthy countries

<p>Abstract</p> <p>Background</p> <p>In the face of the HIV/AIDS epidemic that has contributed to the dramatic increase in orphans and abandoned children (OAC) worldwide, caregiver attitudes about HIV, and HIV-related stigma, are two attributes that may affect caregiving. Little research has considered the relationship between caregiver attributes and caregiver-reported HIV-related stigma. In light of the paucity of this literature, this paper will describe HIV-related stigma among caregivers of OAC in five less wealthy nations.</p> <p>Methods</p> <p>Baseline data were collected between May 2006 through February 2008. The sample included 1,480 community-based and 192 institution-based caregivers. Characteristics of the community-based and institution-based caregivers are described using means and standard deviations for continuous variables or counts and percentages for categorical variables. We fit logistic regression models, both for the full sample and separately for community-based and institution-based caregivers, to explore predictors of acceptance of HIV.</p> <p>Results</p> <p>Approximately 80% of both community-based and institution-based caregivers were female; and 84% of institution-based caregivers, compared to 66% of community-based caregivers, said that they would be willing to care for a relative with HIV. Similar proportions were reported when caregivers were asked if they were willing to let their child play with an HIV-infected child. In a multivariable model predicting willingness to care for an HIV-infected relative, adjusted for site fixed effects, being an institution-based caregiver was associated with greater willingness (less stigma) than community-based caregivers. Decreased willingness was reported by older respondents, while willingness increased with greater formal education. In the adjusted models predicting willingness to allow one's child to play with an HIV-infected child, female gender and older age was associated with less willingness. However, willingness was positively associated with years of formal education.</p> <p>Conclusions</p> <p>The caregiver-child relationship is central to a child's development. OAC already face stigma as a result of their orphaned or abandoned status; the addition of HIV-related stigma represents a double burden for these children. Further research on the prevalence of HIV-related acceptance and stigma among caregivers and implications of such stigma for child development will be critical as the policy community responds to the global HIV/AIDS orphan crisis.</p

PROPERTIES OF CALCIUM FLUORIDE MONOCRYSTALS IN THE ULTRA LOW FREQUENCY RANGE, SPACE CHARGE AND IMPURITY EFFECTS

Les propriétés diélectriques de plusieurs monocristaux de Fluorure de Calcium ont été étudiées dans un grand intervalle de température au moyen de plusieurs méthodes expérimentales complémentaires. Nous avons enregistré la composante en phase et la composante en opposition de phase du courant alternatif en très basse fréquence, ainsi que la répartition de potentiel par la méthode du fil vibrant. Enfin d'autres méthodes (effet électret) peuvent aussi être utilisées. Nous avons obtenu de nombreux renseignements sur les effets de conduction et les effets interfaciaux, et nous avons pu distinguer les effets en volume et en surface. Deux, et plus souvent trois relaxations apparaissent dans les monocristaux étudiés. Les deux premières sont dues aux impuretés, et la troisième est un phénomène de diffusion de Warburg par dessus une barrière superficielle. Ce phénomène de diffusion dépend de la tension continue et de l'atmosphère. On discute la liaison entre relaxations dues aux impuretés et effet électret.Dielectric properties of some monocrystalline CaF2 samples were studied in a large temperature range, with several experimental methods : Ultra low frequency Ac recording apparatus, potential distribution vibrating wire method and electret recording where used. Much information was obtained on conduction and interfacial effects, bulk and electrode relaxations being differentiated. Two or three relaxations are often observed : the first two are impurity effects, but the third is a Warburg diffusion above the surface barrier, with intrinsic activation energy. The Warburg phenomenon appears as an electrode effect in potential distribution measurements and it depends on voltage and surrounding atmosphere. Among the impurity effects, one finds a 1.25-1.30 eV relaxation in all the samples — this relaxation is linked to an electret previously studied

Relaxation de charge d'espace avec électrodes partiellement bloquantes et effet Maxwell Wagner : Application au nylon 66 (Hexaméthylène adipamide)

We have found a very reliable relaxation phenomenon in nylon 66. We were able to interpret the U. L. F. comportment of the samples by using the Friauf's theory improved by recent calculations. When a few DC volts are superposed the relaxation phenomenon disappears in good agreement with permanent space charge theories.On a trouvé un effet de relaxation très net et reproductible sur le nylon [1] et on a associé aux mesures TBF de constante diélectrique des mesures de répartition de potentiel pour s'assurer qu'il s'agissait bien d'un phénomène d'électrodes ; la valeur constante lorsqu'on opère successivement à différentes températures du maximum de la courbe donnant le facteur de pertes en fonction de la fréquence ferait penser à un effet Maxwell Wagner, mais une tension de quelques volts en série avec l'échantillon supprime ce phénomène de relaxation. Comme il existe une impossibilité relative pour les porteurs de se décharger aux électrodes aux températures considérées, on a essayé d'interpréter les résultats expérimentaux, en définissant un coefficient de blocage p suivant le modèle de Friauf [2]. On a utilisé les résultats de calculs récents pour montrer que cette hypothèse conduisait, dans le cas d'un seul type de porteurs, à un phénomène de relaxation du type de Debye, et on a pu alors interpréter le coefficient p. Les variations de la fréquence de relaxation et du maximum du facteur de pertes tg θ en fonction de la tension appliquée confirment les hypothèses utilisées : on peut alors généraliser les résultats de Truckhan [3]. Pour les concentrations de porteurs telles que L/LD > 100 (où LD est la longueur de Debye) les effets de charge d'espace ne peuvent se distinguer d'une relaxation de Maxwell Wagner, tant que la tension appliquée est inférieure à 0,3 V. Aux tensions supérieures il n'est plus possible d'utiliser un modèle basé sur la linéarisation du système d'équations différentielles générales régissant le transport des charges dans l'échantillon

Évaluation de la toxicité musculaire de la chimiothérapie lors d’une épreuve fonctionnelle à l'exercice

International audienc