Excited states of spherium

We report analytic solutions of a recently discovered quasi-exactly solvable model consisting of two electrons, interacting {\em via} a Coulomb potential, but restricted to remain on the surface of a $\mathcal{D}$-dimensional sphere. Polynomial solutions are found for the ground state, and for some higher ($L\le3$) states. Kato cusp conditions and interdimensional degeneracies are discussed.Comment: 6 pages, 2 figures, to appear in Mol. Phy

Predator-Induced Vertical Behavior of a Ctenophore

Although many studies have focused on Mnemiopsis leidyi predation, little is known about the role of this ctenophore as prey when abundant in native and invaded pelagic systems. We examined the response of the ctenophore M. leidyi to the predatory ctenophore Beroe ovata in an experiment in which the two species could potentially sense each other while being physically separated. On average, M. leidyi responded to the predator’s presence by increasing variability in swimming speeds and by lowering their vertical distribution. Such behavior may help explain field records of vertical migration, as well as stratified and near-bottom distributions of M. leidyi

Genetic analysis of leaf rolling in wheat

Dissertação de mestrado em Química Farmacêutica Industrial, apresentada à Faculdade de Farmácia da Universidade de CoimbraAtualmente, as doenças neurodegenerativas como a isquemia cerebral, Alzheimer e Parkinson atacam em massa a população mundial. O acréscimo destas patologias crê-se estar relacionado com falhas na homeostase de zinco e de espécies reativas de oxigénio (ROS) no sistema nervoso central. Neste trabalho questões desta natureza foram investigadas nas sinapses das fibras musgosas da área CA3 do hipocampo de rato. Os estudos foram efetuados em fatias cerebrais utilizando sondas fluorescentes de zinco e de espécies reativas de oxigénio. Sinais intracelulares de zinco foram medidos utilizando o indicador Newport Green na forma permeante, que não complexa o zinco presente nas vesículas sinápticas e que é co-libertado com o glutamato. As variações de zinco foram induzidas por meio de despolarizações com KCl ou usando um meio extracelular com TEA e rico em cálcio. No primeiro caso verificou-se um aumento significativo dos sinais de fluorescência de zinco. Os resultados obtidos usando antagonistas de recetores de glutamato e um bloqueador de canais de cálcio dependentes do potencial, indicam que aqueles sinais têm origem na zona pós-sináptica. No meio com TEA e muito cálcio, usado para induzir quimicamente a potenciação de longa duração, que se considera representar uma forma de memorização ao nível celular, verificou-se uma diminuição reversível da intensidade de fluorescência. Este facto pode ser devido à activação, pelo zinco libertado, de canais de K/ATP pré-sinápticos, o que origina a hiperpolarização da membrana e uma diminuição na libertação de zinco. Alterações na formação de espécies reativas de oxigénio foram estudadas, por meio da sonda H2DCFDA permeante, que é sensível essencialmente aos radicais hidroxilo e peróxido de hidrogénio. Os resultados obtidos, induzidos de forma semelhante aos de zinco, têm dum modo geral um comportamento idêntico ao destes sinais Inúmeros avanços na indústria e na medicina prometem melhorias ao nível das patologias anteriormente mencionadas e outras. No entanto, existe o reverso da moeda, o aumento da industrialização e de fármacos disponíveis provoca um aumento da poluição em efluentes e águas residuais, tendo em conta que os processos usados nas estações de tratamento não são totalmente eficazes. III O sulfametoxazole (SMX) é um antibiótico largamente utilizado, que não é totalmente metabolizado pelo organismo, tendo por isso vindo a ser detetado em águas residuais. Os sinais de zinco medidos aumentam quando as fatias são expostas a esta sulfonamida, voltando ao nível inicial após a mudança para o meio extracelular normal. O efeito do sulfametoxazole nas espécies reativas de oxigénio também foi testado, tendo-se verificado um aumento daquelas espécies na presença de SMX. Os resultados mostram que a ação deste antibiótico não é reversível, por este motivo, as quantidades ambientais de SMX nas águas residuais assumem uma preocupação crescente. A observação de efeitos irreversíveis na formação de espécies reactivas de oxigénio durante actividade neuronal intensa, sugere que aquele fármaco pode contribuir para diversas patologias neurodegenerativas.Currently, neurodegenerative diseases such as cerebral ischemia, Alzheimer's and Parkinson's mass attack the world population. The increase of these diseases is believed to be related to failures in the homeostasis of zinc and of reactive oxygen species in the central nervous system. In this work such issues have been investigated in the mossy fiber synapses from area CA3 of the rat hippocampus. The studies were performed in brain slices using fluorescent probes of zinc and of reactive oxygen species. Intracellular zinc signals were measured using the indicator Newport Green in the permeant form, that does not complex the zinc present in the synaptic vesicles which is co-released with glutamate. The zinc changes were induced by KCl depolarization or applying an extracellular medium containing TEA and rich in calcium. In the first case a significant increase of the fluorescence zinc signals was observed. The results obtained using antagonists of glutamate receptors and one blocker of voltage-dependent calcium channels, indicate that those signals have a postsynaptic origin. In the medium containing TEA and high calcium, used to chemically induce long-term potentiation, which is considered to represent a way of memory formation at the cellular level, a reversible decrease of the fluorescence intensity was observed. This fact may be due to the activation, by released zinc, of presynaptic K / ATP channels, which leads to membrane hyperpolarization and to a decrease in zinc release. Changes in the formation of reactive oxygen species were studied by means of the permeant H2DCFDA probe, which is specially sensitive to the hydroxyl and hydrogen peroxide radicals. The results, induced in a similar way as for zinc, have in general an identical behaviour to that of these signals. Numerous advances in industry and medicine promise improvements in the above mentioned pathologies and others. However, there is the reverse of the coin, the increasing industrialization and availability of drugs results in increased pollution in waste waters and effluents, since the processes used in water treatment plants are not entirely effective. V Sulfamethoxazole (SMX) is a widely used antibiotic, which is not fully metabolized by the organism and, for this reason, is being detected in wastewaters. The measured zinc signals increase when the slices are exposed to this sulfonamide, returning to the initial level after changing to the normal extracellular medium. The effect of sulfamethoxazole in reactive oxygen species was also tested, having been observed an increase of those species in the presence of SMX. The results show that the action of this antibiotic is not reversible, therefore, their environmental quantities in wastewaters are of growing concern. The observation of irreversible effects on the formation of reactive oxygen species during intense neuronal activity, suggests that that pharmaceutical agent may contribute to various neurodegenerative pathologie

Clusters of galaxies : observational properties of the diffuse radio emission

Clusters of galaxies, as the largest virialized systems in the Universe, are ideal laboratories to study the formation and evolution of cosmic structures...(abridged)... Most of the detailed knowledge of galaxy clusters has been obtained in recent years from the study of ICM through X-ray Astronomy. At the same time, radio observations have proved that the ICM is mixed with non-thermal components, i.e. highly relativistic particles and large-scale magnetic fields, detected through their synchrotron emission. The knowledge of the properties of these non-thermal ICM components has increased significantly, owing to sensitive radio images and to the development of theoretical models. Diffuse synchrotron radio emission in the central and peripheral cluster regions has been found in many clusters. Moreover large-scale magnetic fields appear to be present in all galaxy clusters, as derived from Rotation Measure (RM) studies. Non-thermal components are linked to the cluster X-ray properties, and to the cluster evolutionary stage, and are crucial for a comprehensive physical description of the intracluster medium. They play an important role in the cluster formation and evolution. We review here the observational properties of diffuse non-thermal sources detected in galaxy clusters: halos, relics and mini-halos. We discuss their classification and properties. We report published results up to date and obtain and discuss statistical properties. We present the properties of large-scale magnetic fields in clusters and in even larger structures: filaments connecting galaxy clusters. We summarize the current models of the origin of these cluster components, and outline the improvements that are expected in this area from future developments thanks to the new generation of radio telescopes.Comment: Accepted for the publication in The Astronomy and Astrophysics Review. 58 pages, 26 figure

Genetic improvement of wheat for dry environments - a trait based approach

Item does not contain fulltext23 januari 201

Swimming with Predators and Pesticides: How Environmental Stressors Affect the Thermal Physiology of Tadpoles

To forecast biological responses to changing environments, we need to understand how a species’s physiology varies through space and time and assess how changes in physiological function due to environmental changes may interact with phenotypic changes caused by other types of environmental variation. Amphibian larvae are well known for expressing environmentally induced phenotypes, but relatively little is known about how these responses might interact with changing temperatures and their thermal physiology. To address this question, we studied the thermal physiology of grey treefrog tadpoles (Hyla versicolor) by determining whether exposures to predator cues and an herbicide (Roundup) can alter their critical maximum temperature (CTmax) and their swimming speed across a range of temperatures, which provides estimates of optimal temperature (Topt) for swimming speed and the shape of the thermal performance curve (TPC). We discovered that predator cues induced a 0.4uC higher CTmax value, whereas the herbicide had no effect. Tadpoles exposed to predator cues or the herbicide swam faster than control tadpoles and the increase in burst speed was higher near Topt. In regard to the shape of the TPC, exposure to predator cues increased Topt by 1.5uC, while exposure to the herbicide marginally lowered Topt by 0.4uC. Combining predator cues and the herbicide produced an intermediate Topt that was 0.5uC higher than the control. To our knowledge this is the first study to demonstrate a predator altering the thermal physiology of amphibian larvae (prey) by increasing CTmax, increasing the optimum temperature, and producing changes in the thermal performance curves. Furthermore, these plastic responses of CTmax and TPC to different inducing environments should be considered when forecasting biological responses to global warming.Peer reviewe