Variação temporal do desempenho de dye-sensitized solar cells

Mestrado em Engenharia FísicaNeste trabalho produziu-se e estudou-se um grupo de 4 dye-sensitized solar cells (células solares activadas por corante), também conhecidas por células de Grätzel, durante um período de 9 meses a fim de se observar, caracterizar e compreender a variação do desempenho e do comportamento eléctrico e físico de cada uma delas, não só de um ponto de vista qualitativo, mas também quantitativo. Utilizou-se para tal um conjunto de técnicas de caracterização que abrangeram tanto aspectos ópticos e morfológicos (espectrofotometria e microscopia electrónica de varrimento), quanto aspectos eléctricos e difusivos (curvas -, OCVD e espectroscopia de impedância). A partir dos resultados foi possível conhecer alguns factores responsáveis pela degradação do desempenho das células ao longo do tempo, conhecimento este que será útil no aprimoramento destes dispositivos. ABSTRACT: In this work, a group of 4 dye-sensitized solar cells, also known by Grätzel cells, was produced and studied throughout 9 months, in order for the performance, electrical and physical behaviour to be observed, characterized and understood, not only from a qualitative point of view, but also quantitatively. A set of techniques, comprised of spectrophotometry, scanning electron microscopy, - curves, OCVD and impedance spectroscopy was employed to provide optical, morphological, electrical and diffusive information related to each cell. From the collected data, it was possible to figure out a few factors responsible for the observed decrease in the cells’ performance over time, a knowledge that is going to be useful in the improvement of these devices

Toward a DNA Taxonomy of Alpine Rhithrogena (Ephemeroptera: Heptageniidae) Using a Mixed Yule-Coalescent Analysis of Mitochondrial and Nuclear DNA

Aquatic larvae of many Rhithrogena mayflies (Ephemeroptera) inhabit sensitive Alpine environments. A number of species are on the IUCN Red List and many recognized species have restricted distributions and are of conservation interest. Despite their ecological and conservation importance, ambiguous morphological differences among closely related species suggest that the current taxonomy may not accurately reflect the evolutionary diversity of the group. Here we examined the species status of nearly 50% of European Rhithrogena diversity using a widespread sampling scheme of Alpine species that included 22 type localities, general mixed Yule-coalescent (GMYC) model analysis of one standard mtDNA marker and one newly developed nDNA marker, and morphological identification where possible. Using sequences from 533 individuals from 144 sampling localities, we observed significant clustering of the mitochondrial (cox1) marker into 31 GMYC species. Twenty-one of these could be identified based on the presence of topotypes (expertly identified specimens from the species' type locality) or unambiguous morphology. These results strongly suggest the presence of both cryptic diversity and taxonomic oversplitting in Rhithrogena. Significant clustering was not detected with protein-coding nuclear PEPCK, although nine GMYC species were congruent with well supported terminal clusters of nDNA. Lack of greater congruence in the two data sets may be the result of incomplete sorting of ancestral polymorphism. Bayesian phylogenetic analyses of both gene regions recovered four of the six recognized Rhithrogena species groups in our samples as monophyletic. Future development of more nuclear markers would facilitate multi-locus analysis of unresolved, closely related species pairs. The DNA taxonomy developed here lays the groundwork for a future revision of the important but cryptic Rhithrogena genus in Europe

Histaminergic Mechanisms for Modulation of Memory Systems

Encoding for several memory types requires neural changes and the activity of distinct regions across the brain. These areas receive broad projections originating in nuclei located in the brainstem which are capable of modulating the activity of a particular area. The histaminergic system is one of the major modulatory systems, and it regulates basic homeostatic and higher functions including arousal, circadian, and feeding rhythms, and cognition. There is now evidence that histamine can modulate learning in different types of behavioral tasks, but the exact course of modulation and its mechanisms are controversial. In the present paper we review the involvement of the histaminergic system and the effects histaminergic receptor agonists/antagonists have on the performance of tasks associated with the main memory types as well as evidence provided by studies with knockout models. Thus, we aim to summarize the possible effects histamine has on modulation of circuits involved in memory formation

Diagnósticos de enfermagem no setor de hemodinâmica: uma perspectiva adaptativa

Objective: To identify nursing diagnoses of NANDA-I Taxonomy II in patients treated in the Hemodynamics Sector. Method: A descriptive, cross-sectional study with a quantitative approach conducted in a teaching hospital in the interior of Rio Grande do Sul. Data were collected through a sociodemographic characterization instrument and information regarding the problems of physical-physiological adaptation. Results: 100 patients participated in the study. Defining characteristics, risk factors and related factors were identified through adaptation problems. In all, 28 nursing diagnoses were identified, and 13 were considered for the discussion which presented frequency above 50% and represented the main adaptive problems. Protection, neurological and activity and rest components were the most frequent. Conclusion: The recognition of nursing diagnoses facilitates a connection between the main problems of adaptation and nursing interventions

Potencial eólico na costa litoral de Aveiro um estudo de caso

Ponencia presentada en: XXX Jornadas Científicas de la AME y el IX Encuentro Hispano Luso de Meteorología celebrado en Zaragoza, del 5 al 7 de mayo de 2008

Anthropogenic extinction of Pacific land snails: a case study of Rurutu, French Polynesia, with description of eight new species of endodontids (Pulmonata).

Faunistic surveys are fundamental in the conservation of land mollusks, particularly as a means of achieving accurate estimates of species richness and levels of extinction of endangered taxa. The family Endodontidae comprises one of the most diverse groups of indigenous land snails of Pacific Islands. Due to anthropogenic degradation of their habitats, most members of the family are now extinct or severely endangered. In Rurutu, French Polynesia, 11 species of Endodontidae were previously described (10 endemics), but only 1 is known to have been extant during the first half of the 20th Century. Extensive collections made in Rurutu in 2003 recovered only empty shells of these 11 species, as well as of an additional 8 endemic species of endodontids not known to previous investigators: Australdonta oheatora sp. nov., A. anneae sp. nov., A. sibleti sp. nov., A. florencei sp. nov., A. pakalolo sp. nov., A. teaae sp. nov., Minidonta boucheti sp. nov. and M. bieleri sp. nov. The radiation of endodontids in Rurutu was thus much larger than previously envisaged. However, we hypothesize that all species of the family are now extinct in the island

Radiation and decline of endodontid land snails in Makatea, French Polynesia.

The family Endodontidae Pilsbry, 1895 comprised one of the most diverse groups of indigenous land snails of Pacific Islands. However, due to anthropogenic degradation of their habitats and predation by or competition with introduced species, most members of the family are now extinct or severely endangered. Based on limited and sporadic collections, the endodontid fauna of the raised coral island of Makatea in the western Tuamotu Archipelago was known to consist of four valid species, Mautodontha (Mautodontha) daedalea (Gould, 1846), Kleokyphus callimus Solem, 1976, K. hypsus Solem, 1976 and Pseudolibera lillianae Solem, 1976, the last three of which were endemic. To these, we add 18 new species based on a reappraisal of museum collections and analysis of abundant new material collected in 2005: M. (M.) domaneschii, M. (M.) virginiae, M. (M.) harperae, M. (Garrettoconcha) aurora, M. (G.) occidentalis, M. (G.) temaoensis, M. (G.) makateaensis, M. (G.) passosi, M. (G.) spelunca, K. cowiei, P. solemi, P. matthieui, P. cookei, P. aubertdelaruei, P. extincta, P. paraminderae, P. elieporoii, and P. parva. The recently collected material also revealed new information on the morphology, intraspecific variation and distribution of the four previously known species, which are here revised and re-described. With 22 recognized taxa, the radiation of endodontids in Makatea is second in species richness only to that of Rapa Iti in the Austral Islands, from where 24 endodontids have been described. Despite intensive field work in Makatea in 2005, only M. (M.) daedalea was found alive. All other Makatean endodontids were represented solely by empty and worn shells and are probably extinct.