Strategies for the Study of Complex Socio-Economic Systems: an Approach Using Agent-Based Simulation

The present paper proposes a research strategy that integrates top-down and bottom-up approaches, aimed at the study of complex socio-economic systems. Through a theoretical analysis, it is demonstrated throughout the text a strategy that allows the articulation between agent-based simulation approaches and methods of deductive and phenomenological basis capable of providing social sciences with unprecedented accuracy due to ethical and methodological limitations imposed by the study object until then. This is because this type of hybrid approach allows the construction of a deep systemic articulation between the micro and the macro, as advocated by the General Theory of Systems, at the same time as it is supported by systematic experiments that give new light to the study of the socio-economic complexity.     

Evidence for a neuronal release of isotopically labelled γ-amino-n-butyric acid (GABA) from the rat dorsal medulla in vivo

Summary High potassium and electrical stimulation consistently increase efflux of labelled GABA from the in vivo superfused rat dorsal medulla in a calcium-dependent fashion. The depolarizing alkaloid, veratridine, also evokes a large increase in efflux of labelled GABA. These data strongly suggest release from a neurotransmitter pool in this region.Supported by grants from the Science Research Council to N.D. and C.G.D., FAPESP and CNPq (Brazil) to J.A.A. and CAPES and FAPESP (Brazil) to N.B.     

An efficient room-temperature silicon-based light-emitting diode

There is an urgent requirement for an optical emitter that is compatible with standard, silicon-based ultra-large-scale integration (ULSI) technology. Bulk silicon has an indirect energy bandgap and is therefore highly inefficient as a light source, necessitating the use of other materials for the optical emitters. However, the introduction of these materials is usually incompatible with the strict processing requirements of existing ULSI technologies. Moreover, as the length scale of the devices decreases, electrons will spend increasingly more of their time in the connections between components; this interconnectivity problem could restrict further increases in computer chip processing power and speed in as little as five years. Many efforts have therefore been directed, with varying degrees of success, to engineering silicon-based materials that are efficient light emitters. Here, we describe the fabrication, using standard silicon processing techniques, of a silicon light-emitting diode (LED) that operates efficiently at room temperature. Boron is implanted into silicon both as a dopant to form a p-n junction, as well as a means of introducing dislocation loops. The dislocation loops introduce a local strain field, which modifies the band structure and provides spatial confinement of the charge carriers. It is this spatial confinement which allows room-temperature electroluminescence at the band-edge. This device strategy is highly compatible with ULSI technology, as boron ion implantation is already used as a standard method for the fabrication of silicon devices.     

A simple staining technique for electron microscopy with lead-uranyl acetate

Resumen Mediante el empleo de una solución saturada de acetato de uranilo-plomo en acetona de 70%, durante el proceso convencional de deshidratación, se ha conseguido incrementar marcadamente el contraste electrónico en ápices radicales dePhalaris canariensis, sin riesgo alguno de contaminación o deformación de las estructuras.     

Transcriptome analysis of the acoelomate human parasite Schistosoma mansoni

Schistosoma mansoni is the primary causative agent of schistosomiasis, which affects 200 million individuals in 74 countries. We generated 163,000 expressed-sequence tags (ESTs) from normalized cDNA libraries from six selected developmental stages of the parasite, resulting in 31,000 assembled sequences and 92% sampling of an estimated 14,000 gene complement. By analyzing automated Gene Ontology assignments, we provide a detailed view of important S. mansoni biological systems, including characterization of metazoa-specific and eukarya-conserved genes. Phylogenetic analysis suggests an early divergence from other metazoa. The data set provides insights into the molecular mechanisms of tissue organization, development, signaling, sexual dimorphism, host interactions and immune evasion and identifies novel proteins to be investigated as vaccine candidates and potential drug targets.     

Effects of hypophysectomy and thyroidectomy on the glycogen depletion in livers of rats treated with thioacetamide

Zusammenfassung Die Verarmung von Glykogen in der Leber als Ausdruck der toxischen Wirkung von Thioacetamid kann durch Hypophysektomie oder Thyroidektomie verhindert werden.     

Do prostaglandins mediate the somatostatin preventive effect on gastric lesion?

The inhibition of endogenous prostaglandin synthesis by indomethacin treatment blocks the somatostatin preventive effect on the gastric lesions induced in a stress model and has no preventive effect on an intragastric distension model.