Acute physical exercise improves shifting in adolescents at school: evidence for a dopaminergic contribution

The executive function of shifting between mental sets demands cognitive flexibility. Based on evidence that physical exercise fostered cognition, we tested whether acute physical exercise can improve shifting in an unselected sample of adolescents. Genetic polymorphisms were analyzed to gain more insight into possibly contributing neurophysiological processes. We examined 297 students aged between 13 and 17 years in their schools. Physical exercise was manipulated by an intense incremental exercise condition using bicycle ergometers and a control condition which involved watching an infotainment cartoon while sitting calm. The order of conditions was counterbalanced between participants. Shifting was assessed by a switching task after both conditions. Acute intense physical exercise significantly improved shifting as indicated by reduced switch costs. Exercise-induced performance gains in switch costs were predicted by a single nucleotide polymorphism (SNP) targeting the Dopamine Transporter (DAT1/SLCA6A3) gene suggesting that the brain dopamine system contributed to the effect. The results demonstrate the potential of acute physical exercise to improve cognitive flexibility in adolescents. The field conditions of the present approach suggest applications in schools

Assessment of Gas-Surface Interaction Models for Computation of Rarefied Hypersonic Flow

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76727/1/AIAA-36375-113.pd

Eunotiaceae (Bacillariophyceae) em igarapés da Amazônia Central, Manaus e Presidente Figueiredo, Brasil

Estudos florísticos e taxonômicos envolvendo diatomáceas são escassos para a região amazônica. As publicações existentes incluem registros de diatomáceas da Amazônia brasileira, do Equador, da Colômbia e do Peru e comumente mostram que Eunotia e Actinella (Eunotiaceae) são gêneros bem representados nessa região. A maioria dos igarapés amazônicos costuma apresentar potencial hidrogeniônico (pH) ácido, característica aquática que promove o desenvolvimento de uma comunidade típica de diatomáceas, dominada por espécimes de Eunotiaceae. O objetivo deste trabalho foi providenciar um levantamento florístico das espécies de Eunotiaceae presentes em igarapés da Amazônia Central brasileira e registrar os morfotipos de algumas espécies. Amostras fitoplanctônicas e perifíticas foram coletadas em cinco igarapés na rodovia BR-174, em Manaus e Presidente Figueiredo, em setembro e outubro de 1996 e fevereiro e março de 1997. Lâminas permanentes foram preparadas de acordo com a técnica de oxidação lenta para o estudo qualitativo. Vinte e três espécies pertencentes ao gênero Eunotia e seis ao gênero Actinella foram determinadas. Chaves dicotômicas de identificação, descrição detalhada, comentários relevantes e ilustrações foram providenciadas para cada táxon determinado. Morfotipos foram documentados para Eunotia zygodon. Espécies raramente citadas na literatura foram registradas, tais como, Eunotia falcifera e Eunotia rostellata.Floristic and taxonomical studies about diatoms to Amazonian region are commonly well represented by Eunotia and Actinella (Eunotiaceae). The available works include diatom assemblage from Brazilian, Ecuadorian, Colombian and Peruvian Amazonia. The local streams often present acid pH which provides environmental conditions to develop a very particular diatom community dominated by specimens of Eunotiaceae. Thus, the aim of this paper is to give a floristic survey of Eunotiaceae from central Amazonian rivers and to register the typical morphologic frustule variations of some species. Planktonic and periphytic samples were collected from five rivers located at the BR-174 highway, near Manaus and Presidente Figueiredo districts, during 1996 and 1997. Slides were prepared in accordance with the technique of slow oxidation for the qualitative determination. Twenty-three species of Eunotia and six of Actinella were identified. Dicotomic keys, taxonomic comments and photographic illustrations were added. Morphotypes of Eunotia zygodon were registered. Species scarcelly mentioned on diatom literature were registered, such as, Eunotia falcifera and Eunotia rostellata