Exoplanet Characterization and the Search for Life

Over 300 extrasolar planets (exoplanets) have been detected orbiting nearby stars. We now hope to conduct a census of all planets around nearby stars and to characterize their atmospheres and surfaces with spectroscopy. Rocky planets within their star's habitable zones have the highest priority, as these have the potential to harbor life. Our science goal is to find and characterize all nearby exoplanets; this requires that we measure the mass, orbit, and spectroscopic signature of each one at visible and infrared wavelengths. The techniques for doing this are at hand today. Within the decade we could answer long-standing questions about the evolution and nature of other planetary systems, and we could search for clues as to whether life exists elsewhere in our galactic neighborhood.Comment: 7 pages, 2 figures, submitted to Astro2010 Decadal Revie

Regulation of early signaling and gene expression in the α-particle and bystander response of IMR-90 human fibroblasts

<p>Abstract</p> <p>Background</p> <p>The existence of a radiation bystander effect, in which non-irradiated cells respond to signals from irradiated cells, is well established. To understand early signaling and gene regulation in bystander cells, we used a bio-informatics approach, measuring global gene expression at 30 minutes and signaling pathways between 30 minutes and 4 hours after exposure to α-particles in IMR-90 fibroblasts.</p> <p>Methods</p> <p>We used whole human genome microarrays and real time quantitative PCR to measure and validate gene expression. Microarray analysis was done using BRB-Array Tools; pathway and ontology analyses were done using Ingenuity Pathway Analysis and PANTHER, respectively. We studied signaling in irradiated and bystander cells using immunoblotting and semi-quantitative image analysis.</p> <p>Results</p> <p>Gene ontology suggested signal transduction and transcriptional regulation responding 30 minutes after treatment affected cell structure, motility and adhesion, and interleukin synthesis. We measured time-dependent expression of genes controlled by the NF-κB pathway; matrix metalloproteinases 1 and 3; <it/>chemokine ligands 2, 3 and 5 and <it/>interleukins 1β, 6 and 33. There was an increased response of this set of genes 30 minutes after treatment and another wave of induction at 4 hours. We investigated AKT-GSK3β signaling and found both AKT and GSK3β are hyper-phosphorylated 30 minutes after irradiation and this effect is maintained through 4 hours. In bystander cells, a similar response was seen with a delay of 30 minutes. We proposed a network model where the observed decrease in phosphorylation of β-catenin protein after GSK3β dependent inactivation can trigger target gene expression at later times after radiation exposure</p> <p>Conclusions</p> <p>These results are the first to show that the radiation induced bystander signal induces a widespread gene expression response at 30 minutes after treatment and these changes are accompanied by modification of signaling proteins in the PI3K-AKT-GSK3β pathway.</p

Melamine in foodstuffs: from crisis to accreditation

Within the context of the new legislation, the Scientifi c Institute for Public Health developed a method for detecting melamine in milk,milk powder, milk products, confectionery and fl our of plant origin. The method is easy to use and allows the fast processing of largenumbers of samples.</p

Comment estimer l&#039;incertitude de mesure lors de la quantification de pesticides ?

Pour evaluer l&#039;incertitude de mesure sur la concentration d&#039;un pesticide, plusieurs approches peuvent etre envisagees pour autant qu&#039;elles cadrent avec le GUM (Guide to the expression of uncertainty in measurement) et la norme ISO 17025. L&#039;EURL Pesticides &quot;Fruits and Vegetables&quot; a estime l&#039;incertitude associee a differents pesticides a une concentration de 10 ppb par le biais de différentes methodes. L&#039;approche &quot;bottom up&quot; n&#039;a pas ete utilisee en raison de sa complexite, l&#039;approche &quot;top-down&quot; evalue l&#039;incertitude a 54 %, la methode SANCO donne une incertitude de 50 %, enfin l&#039;equation de Thompson estime l&#039;incertitude a 44 %.</p

Le glyphosate dans tous ses états

The determination of glyphosate at trace level is unquestionably complicated. However, if the correct analytical method is chosen, rather effective results can be achieved. In our case, the choice of isotope dilution quantification has allowed us to achieve a good yield without having to worry about potential losses during the rapid stage (1 min) of simultaneous extraction-purification. Derivatisation has been a success since it allows us to easily incorporate the analysis of glyphosate into routine analyses without making any changes instrumentally, which therefore represents a considerable time saving benefit.</p

Screening de résidus de pesticides par analyseur à temps de vol (ToF) : Mythe ou réalité?

L&#039;interet du spectrométre de type &quot;time of flight&quot; pour l&#039;analyse des pesticides</p