Mass Marking of Mosquitofish: Preliminary Results

Three marking techniques were tested to determine their applicability for mosquitofish. Tetracycline drugs and DC Ar administered in the diet successfully marked laboratory-cultured mosquitofish, but exposure to direct sunlight in outdoor tanks resulted in the rapid disappearance of the marks. Preliminary data on fluorescent marks from a polystyrene pigment in a melamine-sulfonamide-formaldehyde resin forced into the dermal ,tissue with compressed air are more promising. A t an optimal deliver pressure of 7.3 m Hg (140 p.s.i.) and spraying time of 15 sec., marking percentage is maximized and fish mortality is minimized. Mark retention time was up to 80 days in outdoor tanks at this writing, Long retention times and the availability of four colors increases the potential of this marking technique as a useful tool in field population studies of mosquito fish

Perspectives historiques et contemporaines sur la transition de l’école au travail : apports théoriques et méthodologiques du modèle développemental-contextuel

Les travaux d’Erikson sur les périodes de l’enfance et de l’adolescence offrent un cadre intéressant pour la compréhension des multiples transitions développementales qui conduisent du jeu au travail. Selon Erikson, le développement s’effectue en plusieurs étapes séquentielles, ou stades psychologiques, caractérisés par une épreuve spécifique, ou crise. Chaque crise psychologique doit être affrontée et résolue avant que la personne identifie et affronte la crise suivante. Dans le meilleur des cas, cette suite d’épreuves aboutit au développement de la confiance, de l’autonomie, de « l’industrie », et de l’identité, dans cet ordre, au cours de l’enfance, de l’adolescence et de l’entrée dans l’âge adulte. Cette séquence épigénétique de transitions invariables a été remise en question par les changements de la société moderne que les sociologues appellent la modernisation du cours de la vie. Des formulations plus récentes selon lesquelles les transitions sont modulées par les caractéristiques individuelles et par les multiples niveaux de contextes de l’époque offrent de nouvelles possibilités de conceptualisation. Une attention particulière est portée aux méthodologies de recherche capables de prendre la personne-en-contexte comme unité d’analyse, en tenant compte à la fois du développement de la personne et du contexte toujours changeant.Erikson’s insights into the experience of childhood and adolescence offer a promising framework for illuminating the multiple developmental transitions that lead from play to work. According to Erikson, development proceeds through several sequential psychosocial stages or phases that are delineated from one another by a unique challenge or crisis. Each psychosocial crisis must be confronted and resolved before the person can identify and face this subsequent crisis. Optimally, this sequence of challenges results in the development of trust, autonomy, initiative, industry, and identity, in that order, during enfancy, adolescence, and young adulthood. This epigenetic, invariant sequence of transitions has been called into question by the changing face of modern society, referred to by sociologists as the modernization of the life course. More recent formulations that view the transitions as shaped by individual characteristics and multiple levels of context, as well as historical time, are discussed as alternative conceptualizations. Special attention is given to research methodologies that are able to accommodate the person-in-context as the unit of analysis, thereby taking into account both the developing person and the ever-changing context

Food-web structure in relation to environmental gradients and predator-prey ratios in tank-bromeliad ecosystems

Little is known of how linkage patterns between species change along environmental gradients. The small, spatially discrete food webs inhabiting tank-bromeliads provide an excellent opportunity to analyse patterns of community diversity and food-web topology (connectance, linkage density, nestedness) in relation to key environmental variables (habitat size, detrital resource, incident radiation) and predators: prey ratios. We sampled 365 bromeliads in a wide range of understorey environments in French Guiana and used gut contents of invertebrates to draw the corresponding 365 connectance webs. At the bromeliad scale, habitat size (water volume) determined the number of species that constitute food-web nodes, the proportion of predators, and food-web topology. The number of species as well as the proportion of predators within bromeliads declined from open to forested habitats, where the volume of water collected by bromeliads was generally lower because of rainfall interception by the canopy. A core group of microorganisms and generalist detritivores remained relatively constant across environments. This suggests that (i) a highly-connected core ensures food-web stability and key ecosystem functions across environments, and (ii) larger deviations in food-web structures can be expected following disturbance if detritivores share traits that determine responses to environmental changes. While linkage density and nestedness were lower in bromeliads in the forest than in open areas, experiments are needed to confirm a trend for lower food-web stability in the understorey of primary forests

Proton radiotherapy at PTC Czech in Prague

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Overview of power exhaust experiments in the COMPASS divertor with liquid metals

Power handling experiments with a special liquid metal divertor module based on the capillary porous system technology were performed in the tokamak COMPASS. The performance of two metals (Li and LiSn alloy) were tested for the first time in a divertor under ELMy H-mode conditions. No damage of the capillary mesh and a good exhaust capability were observed for both metals in two separate experiments with up to 12 MW/m(2) of deposited perpendicular, inter-ELM steady-state heat flux and with ELMs of relative energy similar to 3% and a local peak energy fluence at the module similar to 15 kJ.m(-2). No droplets were directly ejected from the mesh top surface and for the LiSn experiment, no contamination of the core and SOL plasmas by Sn was observed. The elemental depth profile analysis of 14 stainless-steel samples located around the vacuum vessel for each experiment provides information about the migration of evaporated/redeposited liquid elements

Modeling of COMPASS tokamak divertor liquid metal experiments

Two small liquid metal targets based on the capillary porous structure were exposed to the divertor plasma of the tokamak COMPASS. The first target was wetted by pure lithium and the second one by a lithium-tin alloy, both releasing mainly lithium atoms (sputtering and evaporation) when exposed to plasma. Due to poorly conductive target material and steep surface inclination (implying the surface-perpendicular plasma heat flux 12-17 MW/m(2)) for 0.1-0.2 s, the LiSn target has reached 900 degrees C under ELMy H-mode. A model of heat conduction is developed and serves to evaluate the lithium sputtering and evaporation and, thus, the surface cooling by the released lithium and consequent radiative shielding. In these conditions, cooling of the surface by the latent heat of vapor did not exceed 1 MW/m(2). About 10(19) lithium atoms were evaporated (comparable to the COMPASS 1 m(3) plasma deuterium content), local Li pressure exceeded the deuterium plasma pressure. Since the radiating Li vapor cloud spreads over a sphere much larger than the hot spot, its cooling effect is negligible (0.2 MW/m(2)). We also predict zero lithium prompt redeposition, consistent with our observation.

Examining smoking-induced differential gene expression changes in buccal mucosa

<p>Abstract</p> <p>Background</p> <p>Gene expression changes resulting from conditions such as disease, environmental stimuli, and drug use, can be monitored in the blood. However, a less invasive method of sample collection is of interest because of the discomfort and specialized personnel necessary for blood sampling especially if multiple samples are being collected. Buccal mucosa cells are easily collected and may be an alternative sample material for biomarker testing. A limited number of studies, primarily in the smoker/oral cancer literature, address this tissue's efficacy as an RNA source for expression analysis. The current study was undertaken to determine if total RNA isolated from buccal mucosa could be used as an alternative tissue source to assay relative gene expression.</p> <p>Methods</p> <p>Total RNA was isolated from swabs, reverse transcribed and amplified. The amplified cDNA was used in RT-qPCR and microarray analyses to evaluate gene expression in buccal cells. Initially, RT-qPCR was used to assess relative transcript levels of four genes from whole blood and buccal cells collected from the same seven individuals, concurrently. Second, buccal cell RNA was used for microarray-based differential gene expression studies by comparing gene expression between a group of female smokers and nonsmokers.</p> <p>Results</p> <p>An amplification protocol allowed use of less buccal cell total RNA (50 ng) than had been reported previously with human microarrays. Total RNA isolated from buccal cells was degraded but was of sufficient quality to be used with RT-qPCR to detect expression of specific genes. We report here the finding of a small number of statistically significant differentially expressed genes between smokers and nonsmokers, using buccal cells as starting material. Gene Set Enrichment Analysis confirmed that these genes had a similar expression pattern to results from another study.</p> <p>Conclusions</p> <p>Our results suggest that despite a high degree of degradation, RNA from buccal cells from cheek mucosa could be used to detect differential gene expression between smokers and nonsmokers. However the RNA degradation, increase in sample variability and microarray failure rate show that buccal samples should be used with caution as source material in expression studies.</p