The disturbing function for polar Centaurs and transneptunian objects

The classical disturbing function of the three-body problem is based on an expansion of the gravitational interaction in the vicinity of nearly coplanar orbits. Consequently, it is not suitable for the identification and study of resonances of the Centaurs and transneptunian objects on nearly polar orbits with the solar system planets. Here, we provide a series expansion algorithm of the gravitational interaction in the vicinity of polar orbits and produce explicitly the disturbing function to fourth order in eccentricity and inclination cosine. The properties of the polar series differ significantly from those of the classical disturbing function: the polar series can model any resonance as the expansion order is not related to the resonance order. The powers of eccentricity and inclination of the force amplitude of a $p$:$q$ resonance do not depend on the value of the resonance order $|p-q|$ but only on its parity. Thus all even resonance order eccentricity amplitudes are $\propto e^2$ and odd ones $\propto e$ to lowest order in eccentricity $e$. With the new findings on the structure of the polar disturbing function and the possible resonant critical arguments, we illustrate the dynamics of the polar resonances 1:3, 3:1, 2:9 and 7:9 where transneptunian object 471325 could currently be locked.Comment: 18 pages, 9 figures, 7 tables. Accepted for publication in Monthly Notices of the Royal Astronomical Societ

A numerical investigation of coorbital stability and libration in three dimensions

Motivated by the dynamics of resonance capture, we study numerically the coorbital resonance for inclination180 >=I>=0 in the circular restricted three-body problem. We examine the similarities and differences between planar and three dimensional coorbital resonance capture and seek their origin in the stability of coorbital motion at arbitrary inclination. After we present stability maps of the planar prograde and retrograde coorbital resonances, we characterize the new coorbital modes in three dimensions. We see that retrograde mode I (R1) and mode II (R2) persist as we change the relative inclination, while retrograde mode III (R3) seems to exist only in the planar problem. A new coorbital mode (R4) appears in 3D which is a retrograde analogue to an horseshoe-orbit. The Kozai-Lidov resonance is active for retrograde orbits as well as prograde orbits and plays a key role in coorbital resonance capture. Stable coorbital modes exist at all inclinations, including retrograde and polar obits. This result confirms the robustness the coorbital resonance at large inclination and encourages the search for retrograde coorbital companions of the solar system's planets.Comment: accepted for publication in Celestial Mechanics and Dynamical Astronom

Biotic and abiotic interactions in temporary summer pools of southern Portugal

In the south of Portugal, the summer season is characterized by reduced precipitation and high air temperatures, which causes the disruption of surface flow and subsequent formation of disconnect pools that may dry out entirely. During this dry period, there is a natural decrease of water quality standards due to the lack of water, leaving temporary rivers very vulnerable. Nevertheless, the remaining pools and surroundings become important in the survival of biological communities. Aquatic macroinvertebrates were sampled in several pools during the summer period (in the beginning and before the ending), in temporary tributaries of the Degebe River (Guadiana catchment), to quantify the response of macroinvertebrates communities to seasonal desiccation and habitat fragmentation. It we collected thousands individuals, representing 27 families of macroinvertebrates. Changes in the composition and abundance were affected by temporal variability in pool volume and location in the watershed. Smaller, upstream pools showed less diversity and abundance than downstream pools. Higher biological interactions and higher level of relationships with terrestrial ecosystems were perceptible for smaller summer pools. Pools were typically dominated by tolerant taxa such as midge larvae (Chironomidae), lesser boatman (Corixidae) and Oligochaeta, resulting in low diversity of communities over time. The results indicated the importance and impact of changes in habitat quality, size and connectivity in aquatic macroinvertebrates communities. They also revealed the importance of preservation and conservation of temporary ecosystems, particularly during the dry season, when the anthropogenic interference in ecosystems is more evident and can jeopardize the biodiversity maintenance of these systems

Diatom assemblages in Portuguese temporary rivers

During a survey of benthic diatoms in watercourses from Portugal in spring and summer 2006 and 2007, 76 sites in temporary streams (according to the National Water Institute classification) have been studied. These streams belong to the Ribeiras do Algarve (10 sites), Guadiana (19 sites), Mira (7 sites), Sado (16 sites), Tejo (20 sites), and Douro (4 sites) watersheds. Among these 76 sites, the National Water Institute classified only 48 as reference sites, and only these were therefore considered in the statistical analysis performed. A total of 276 diatom taxa have been identified in the 48 reference sites, from which 112 were present in abundance above 2% in at least one inventory. The most frequent taxa, present in more than 50% of the studied sites, were Achnanthidium minutissimum (Kützing) Czarnecki, Amphora pediculus (Kützing) Grunow, Cocconeis euglypta Ehrenberg, Eolimna minima (Grunow) Lange-Bertalot, Gomphonema parvulum Kützing, G. rosenstockianum Lange-Bertalot & E. Reichardt, Navicula gregaria Donkin, N. veneta Kützing, Nitzschia inconspicua Grunow and Planothidium frequentissimum (Lange-Bertalot) Lange-Bertalot. These are neutrophilous to alcaliphilous, mesosaprobous to -meso-saprobous, eutraphentic to indifferent taxa. Furthermore, a multivariate analysis relating diatom assemblages with environmental parameters is presented and the ecological preferences of not yet well known taxa, such as G. rosenstockianum, are provided

Depleção do DNA mitocondrial (mtDNA) em leucócitos de doentes com doença Machado-Joseph : um estudo piloto

Dissertação de Mestrado, Ciências Biomédicas, 5 de Outubro de 2015, Universidade dos Açores.A doença de Machado-Joseph (DMJ), também denominada por ataxia espinocerebelosa do tipo 3 (SCA3; OMIM 109150; ORPHA 98757) é uma doença neurodegenerativa autossómica dominante de início tardio, caracterizada por uma expressão clínica variável. A mutação causal da DMJ corresponde a uma expansão instável da repetição CAG no exão 10 do gene ATXN3, localizado em 14q32.1. Esta expansão, traduzida num trato poliglutamínico expandido, concede à proteína ataxina-3 uma função tóxica. Estudos recentes sugerem que danos mitocondriais e variações no DNA mitocondrial (mtDNA) desempenham um papel importante nas doenças poliglutamina (poliQ), tais como a doença de Huntington, a ataxia espinocerebelosa do tipo 2, a SCA3 e a atrofia muscular espino-bulbar. A ocorrência destes danos, através da acumulação de alterações qualitativas e quantitativas, correlaciona-se com o declínio da função mitocondrial; dada a importância desempenhada pelas mitocôndrias em determinadas vias metabólicas, nomeadamente, apoptóticas, estas contribuem para o processo de envelhecimento, constituindo deste modo um fator de interesse nas doenças poliQ. As evidências atuais sugerem uma maior suscetibilidade aos efeitos do stress oxidativo e uma incapacidade de proteção contra os radicais livres. Para a DMJ a literatura científica disponível para alterações mitocondriais é reduzida e com resultados controversos, contudo alguns estudos parecem sugerir que, tal como em outras doenças poliQ, alterações nos mecanismos de proteção contra o stress oxidativo poderão desempenhar um papel na patogenicidade desta doença. Sendo que a alteração no número de cópias do mtDNA foi reportada na DMJ, o objetivo principal do presente estudo consiste na avaliação do potencial das alterações no número de cópias de mtDNA como biomarcador de estado e de progressão da DMJ.ABSTRACT: Machado-Joseph disease (MJD), also known as spinocerebellar ataxia type 3 (SCA3), is an autossomal dominant late-onset neurodegenerative disorder characterized by clinical heterogeneity, namely in the appearance of first symptoms. MJD is caused by an expansion of a CAG repeat in the ATXN3 gene, located at 14q32.1, which is translated into a poliglutamine (polyQ) tract, promoting a toxic gain of function to the ataxin-3 protein. Current studies suggest that mitochondrial DNA (mtDNA) alterations play an important role in several age-related neurodegenerative diseases, including polyQ diseases such as Huntington's disease, spinocerebellar ataxia type 2, SCA3 and spinobulbar muscular atrophy. The accumulation of qualitative and quantitative mtDNA alterations correlates with the mitochondrial function decline ; moreover, mitochondria plays an important role in several metabolic pathways, in particular, apoptotis, which could contribute to the aging process, thus constituting a factor of interest in polyQ diseases. Some evidences suggest that oxidative stress-associated mechanisms dysfunction may play a role in the pathogenesis of MJD. Moreover, alterations in the mtDNA copy number as well as the presence of deletions have been reported. The main goal of the present study is to investigate the potential of mtDNA copy number biomarker of MJD status as well as biomarker of progression

Criatividade: investimento pessoal e organizacional para o séc. XXI?

Após serem tecidos alguns consensos acerca do que é, e não é, criatividade, serão identificados recursos essenciais para ela se manifestar. Criatividade mostrar-se-á então como uma simultaneidade de competências cognitivas, motivacionais, emocionais e sociais. Estando desenhados contornos do que se pode entender pelo conceito, importará questionar como tal conceito pode interessar à gestão de uma carreira pessoal e ao mundo organizacional. Passos como a identificação e a promoção dos recursos criativos ensaiarão a resposta de que a criatividade pode ser pensada como uma competência fundamental, e passível de ser fomentada, num século em que a necessidade de uma resolução inovadora de problemas se impõe no quotidian

The transatlantic introduction of weakfish Cynoscion regalis (Bloch & Schneider, 1801) (Sciaenidae, Pisces) into Europe

Weakfish Cynoscion regalis (Bloch and Schneider, 1801) is a sciaenid fish native to the east coast of North America and has been recently collected in three areas of the Iberian Peninsula (Europe). We aimed to i) provide the first report of the presence of weakfish in Europe, ii) hypothesize the most likely introduction vector, iii) discuss the potential for ecological overlap between weakfish and meagre Argyrosomus regius (Asso, 1801), the native Sciaenidae species, and iv) highlight the importance of citizen science in the detection of nonnative species. Weakfish were captured in the Sado estuary (July 2014), Gulf of Cadiz (November 2015) and the adjacent Guadiana estuary (June 2016), and in two Galician Rías (June 2016). Anglers reported that weakfish was present in the Sado estuary for “some” years, while their presence was only noticed recently in the other two areas. We hypothesize that ballast water was the introduction vector, that weakfish established a reproducing population in the non-native range, and that it dispersed from the Sado estuary, a central region of its current distribution range. The Sado estuary might have been the introduction area for weakfish via ballast water because there is a busy transoceanic commercial port in the estuary. Moreover, they are not used in European aquaculture facilities, nor in the aquarium trade. The collected specimens were ≤50 cm, with average lengths of 30 cm, which corresponds to a median age of 2 years and to individuals capable of reproducing. As a result, the year of introduction must be before 2012. Weakfish have a similar ecological niche to meagre, but the outcome of potential interactions is uncertain. Citizen science, especially the initiative of local fishermen, was critical to detect this non-native species.info:eu-repo/semantics/publishedVersio

Portugaliae Monumenta Misericordiarum, Tradição e Modernidade: o período da Monarquia Constitucional (1834-1910)

Fiel à vocação de uma colectânea deste tipo, cuja amplitude cronológica tinha por objecto recolocar no tempo a realidade hospitaleira das Misericórdias no seu sentido mais vasto, os autores facultam aos interessados um estimulante quadro sobre a forte identidade das Misericórdias, “baluartes a assegurar” em tempos adversos, e a vontade sempre vincada dos seus responsáveis de preservar a sua independência e os seus princípios fundadores na vigência de uma monarquia constitucional

Criatividade: desafios ao conceito

Após estabelecermos alguns elementos consensuais face à questão do que se pode entender por criatividade, essencialmente identificaremos desafios que tal conceito tem vindo a colocar. Emergirão assim a) desafios inerentes à ambiguidade de polémicas conceptuais com implicações práticas; b) desafios para a irradicação de mitos prejudiciais à promoção de criatividade no quotidiano; c) desafios para a gestão de riscos e de potencialidades ns domínio da avaliação. Pretendem ser desafios transversais a variados contextos de vida, face aos quais os leitores, na sua diversidade, se identifique. Pretendem ser ainda desafios abordados genericamente (apenas identificados) com o objectivo de partilhar preocupações que sensibilizem o leitor para o questionamento acerca de uma competência de quase sobrevivência no século XXI