Shelf-Ocean material exchange influencing the Atlantic chemical composition off NW Iberian margin since the last glaciation

Rivers are the main conduit of sediment to the shelf. The basin geology, the drainage area and the discharge rate are the major factors that determine their sediment load (Milliman and Syvistski, 1992). Besides suspended particles, dissolved components may also give some information on the eroded crust. Sr isotopes in carbonate shells of biological organisms have been used to study, in the geological record, the influence exerted by the chemical weathering of the continental crust on the seawater composition (Macdougall, 1991). In this work, Sr isotope ratios obtained in tests of foraminifera representing the last 40 ka are presented and discussed in the scope of the palaeogeographical evolution of NW Iberia. This work aims to present and discuss the results of Sr isotope analyses (performed, by TIMS, in the Isotope Geology Laboratory of the University of Aveiro) of tests of two species of foraminifera, from nine samples taken along the OMEX core KC 024-19 (181 cm; 42°08’98’’N, 10°29´96’’W, and 2765m), collected in the Galicia Bank area, off Galicia. Taking into account that Sr contained in the carbonate tests is usually considered as preserving the signature of the contemporaneous seawater, one planktonic species (Globigerina bulloides) and one benthic species (Cibicides wuellerstorfi) were selected in order to try to detect Sr isotope variations both through time and between two different levels of the water column. The core age model, which records the last 40 ka, is based on a combination of oxygen isotope stratigraphy, eight AMS 14C datings and the synchronisation of the last four Heinrich Events in the Iberian Margin sedimentary records. As a whole, the obtained 87Sr/86Sr ratios vary between 0.709209 and 0.709108, with a mean 2σ error of 0.000025. These values lie within the range of modern marine Sr isotope ratios (0.70910-0.70922), as previously defined using analyses of both seawater and marine carbonates (see compilation by Faure and Mensing, 2005). Despite their small variation, the 87Sr/86Sr ratios obtained in G. bulloides seem to indicate that Sr dissolved in seawater at the KC 024-19 core site became slightly less radiogenic after the Last Glacial Maximum (LGM). This decrease is concomitant with diminishing amounts of the detrital components in the sediments (Fig. 1). Therefore, both the composition of dissolved Sr, as revealed by results on tests of planktonic foraminifera, and the proportions of suspended terrigenous particulate material arriving at the KC 024-19 site point to a decreasing importance of the contribution of the erosion of the Iberian Variscan crust since the Last Glacial Maximum and in the Holocene. The 87Sr/86Sr ratios measured in tests of benthic foraminifera (C. wuellerstorfi) are more erratic and no correlation can be established with palaeogeographical/palaeoclimatic constraints. The difference between the behaviour of Sr compositions in G. bulloides and C. wuellerstorfi may indicate that whilst the planktonic foraminifera should reproduce very closely the seawater composition, the benthic organisms should, in addition to the major role of seawater, also be affected by some sort of interaction with the sediments. As such, planktonic foraminifera are probably more reliable indicators of seawater composition in studies involving very small periods and corresponding very slight variations of the 87Sr/86Sr ratios. Taking into account that G. bulloides is a common planktonic species (living mostly in the first 50m of the water column), whose tests seem to be in equilibrium with sea water composition, variations in its 87Sr/86Sr ratios can be related with changes in the chemical composition of the water of the Atlantic Ocean off NW Iberian Margin. The highest 87Sr/86Sr values are contemporaneous with a period of low sea level (about -140 m; Dias et al., 2000) during the LGM. According to Dias et al. (2000) at 18 ka BP the shoreline was close to the shelf break. The summital parts of the Gerês and Estrela mountains were covered by local glaciers and close to the coast freezing occurred frequently. The river catchments, which extended far to the shelf, received more rainfall due to a longer, compared to present day conditions, wet season, which promoted both physical and chemical weathering. Higher pluviosity combined with the effect of spring ice melting maintained high river discharge and consequently caused very important sediment supply to the coastal zone. The extremely narrow shelf was a very energetic environment due to sea bottom inclination and very limited long wave refraction. Therefore, at that time, a long wet season and very competent rivers should have caused important erosion of the Variscan basement in NW Iberia. Additionally, then, the shoreline was much closer to the KC 024-19 site. The combination of all these factors favoured an important deposition of terrigenous sediments and the local slight enrichment in radiogenic Sr of the seawater. With sea level rise, after the deglaciation and during the Holocene, the river estuaries became progressively far away from the shelf break. Their competence of transport also became progressively reduced and the offshore transport of detrital sediments became progressively lower. Conversely the biogenic carbonate proportion in the sediments increased, due to lower dilution by the terrigenous particles. Simultaneously, the values of 87Sr/86Sr in the seawater at the KC 024-19 site became lower, as a consequence of a complete homogenization with the ocean global composition, which was now more effective with the increasing distance towards shoreline

Transformer and LCL Filter Design for DPFCs

Flexible AC Transmission Systems (FACTS) can be used for power flow control in AC transmission grids, allowing simultaneous control of the bus voltage and line active and reactive power. However, due to high costs and reliability concerns, the application of this technology has been limited in such applications. Recently, the concept of Distributed FACTS (DFACTS) and Distributed Power Flow Controller (DPFC) has been introduced as a low cost high reliability alternative for power flow control. This paper presents the design of a coupling transformer and a LCL filter for DPFC devices. To extract the electromagnetic energy from the transmission line a transformer with a single turn primary is designed and optimized. A third-order LCL filter is used to guarantee high order harmonics filtering. Simulations results are presented and discussed

Marine Operations with the SWORDFISH Autonomous Surface Vehicle

IEEE Robótica 2007 - 7th Conference on Mobile Robots and Competitions, Paderne, Portugal 2007This paper describes the design and development of the Swordfish Autonomous Surface Vehicle (ASV) system. The work focuses the sensors, actuators, communications and C4I of an unmanned vehicle for marine operations. SWORDFISH is an autonomous surface vehicle used as the central communications link between air, undersea, and terrestrial robotic vehicles of a network centric operation. It is used as a test bed platform for deployment and testing of advanced control and operational concepts for multi-vehicles systems. This new unmanned marine vehicle was done in the context of the PISCIS project. The PISCIS project concerns the development, test and evaluation of new vehicles and new concepts of operation for networked vehicle systems in oceanographic data collection. The PISCIS system includes two autonomous underwater vehicles, the Swordfish ASV, an acoustic navigation system, acoustic and radio communications and a distributed command and control system

Behaviour of Human Erythrocyte Aggregation in Presence of Autologous Lipoproteins

The aim of this work was to evaluate in vitro the effect of autologous plasma lipoprotein subfractions on erythrocyte tendency to aggregate. Aliquots of human blood samples were enriched or not (control) with their own HDL-C, LDL-C, or VLDL-C fractions obtained from the same batch by density gradient ultracentrifugation. Plasma osmolality and erythrocyte aggregation index (EAI) were determined. Blood aliquots enriched with LDL-C and HDL-C showed significant higher EAI than untreated aliquots, whereas enrichment with VLDL-C does not induce significant EAI changes. For the same range of lipoprotein concentrations expressed as percentage of osmolality variation, the EAI variation was positive and higher in presence of HDL-C than upon enrichment with LDL-C (P < 0.01). Particle size, up to LDL diameter values, seems to reinforce erythrocyte tendency to aggregate at the same plasma osmolality (particle number) range of values

Control of distributed power flow controllers using active power from homopolar line currents

Flexible AC Transmission Systems (FACTS) devices can be used for power flow control in AC transmission grids, improving power line utilization and performance. Nowadays, Unified Power Flow Controllers (UPFC) are one of the most useful FACTS, allowing the simultaneous control of the bus voltage and line active and reactive power. However, due to high costs and reliability concerns, the utilization of this technology has been limited in such applications. The concept of Distributed FACTS (DFACTS) and Distributed Power Flow Controller (DPFC) was recently introduced as a low coast alternative for power flow control. This paper presents a distributed power flow controller that uses third-harmonic frequency currents transmitted through the line to independently control active and reactive power flow at fundamental frequency. Simulations were carried in the Matlab/Simulink environment. © 2012 IEEE

Orienting axis towards the reform of undergraduate medical education : a strategic approach

São analisadas as circunstancias que antecedem a próxima reforma do ensino medico, enunciados alguns dos principais estímulos (internos e externos) e referidas dificuldades que se interpõem (frequentemente) as mudanças curriculares. A reforma do ensino medico deverá fundamentar-se numa nova filosofia educacional, que privilegie a aprendizagem orientada e considere a pré-graduação como fase preliminar do processo educativo em Medicina. A definição de objectivos gerais e específicos, a programação e definição de estratégias, o continuo acompanhamento do processo educacional, a inventariação e adequação dos meios de acção disponíveis, e o empenhamento concertado de responsáveis políticos, das instituição de ensino, docentes e alunos serão factores indissociáveis de uma reforma bem sucedida. A formação de médicos polivalentes justifica modificações metodológicas, designadamente, a definição de um currículo nuclear, dinamizado através do ensino interdisciplinar que favoreça o contacto precoce com problemas que exijam integração. A interdisciplinaridade contribuirá para a formação plena no âmbito técnico e psicossocial. A metodologia utilizada (no ensino e avaliação) e o empenhamento e qualidade pedagógica dos docentes serão factores determinantes para a reforma que se deseja. A competência profissional será o produto final de uma aprendizagem eficaz. De outro modo, a formação medica pré-graduada terá deficiências que dificultarão a concretização profissional do jovem médico, e se repercutirão durante toda a actividade clinica subsequente.The circumstances preceding the future revision of the medical curriculum are analysed, main internal and external stimuli are described, and sources of resistance to changes in medical training require new educational philosophy, privileging oriented training during undergraduation, as a preliminary phase of medical education. The definition and accompaniment of the general and specific objectives, the strategy and programme used, the design and adequacy of the available support, and the related engagement of all political, academic and socially responsible persons and institutions, are fundamental factors for successful change. The education and training of polyvalent medical doctors requires methodological modifications, namely the definition of a core curriculum, made dynamic through the teaching of interdependent subjects and earlier contact with common clinical problems. Learning through interconnected basic and clinical matters will benefit the technical and psychosocial education of future doctors. The education resulting from a renewal in undergraduate medical education will be mostly determined by organizational and institutional frameworks, teaching methods and the evaluation process used, as well as by teacher commitment, pedagogic and scientific capacities. Professional competence should be the end product of efficient training. Otherwise, undergraduate medical education would not prepare the professional development of the young doctors, thus diminishing the quality of medical training in the future

Biochemical characterization and metabolic effects of the tumor necrosis factor

The tumor necrosis factor, preliminary identified because of its antitumor properties, refers to two kinds of similar polypeptides (TNF or cachectin, and TNF-fl or lymphotoxin), which share some biolo gical effects. Both substances, as members of the class of cytokines, play a role as mediators of inflam mation and the celiular immune response. Human cachectin is produced as a prohormone and activated by cleavage of a 76 residue peptide. Mature cachectin (with comprises 157 aminoacid residues) share a 28% aminoacid sequence homology with lymphotoxin. Both cytokines are encoded by different genes of chromosome 6 and may compete for a common receptor. Cachectin is produced by a wide variety of cells (phagocytic and non-phagocytic), mainly by activated macrophages and monocytes. Different inva sive stimuli (mainly lipopolysaccharide, a constituent of the Gram-negative bacteria’s outer wall) acti vate cachectin biosynthesis, which is controlled chiefly at a post-transcriptional levei. The newiy synthetised cachectin remains associated as a transmembrane form, affecting their targets by direct celi-to-cell contact, or is actively secreted in the circuiation to distant sites in the body, where it binds to high affinity cachectin receptor, on a variety of ccli types. Cachectin exerts pleiotropic effects on nor mal, transformed, or tumoral celis. The biological effects mediate by cachectin may be beneficial or deleterious to the body, depending on the quantity produced, duration of ccli exposure and further biochemical mediators in the enviromment of the target edis. Cachexin (frequently associated with severe infection and cancer) seems to be the result of a persistent exposure to raised leveis of cachectin. This cytokine reguiates the activities of different enzymes, thus increasing adipocyte lypolysis and skele tal myocyte glucose catabolism. and increasing hepatocyte gluconeogenesis and acute-phase protein biosynthesis. A very suggestive effect of cachectin is the anti-tumor activity. This cytotoxic-cytolytic effect include hemorrhage and necrosis of some tumor species through mechanisms still open to discus sion. Eventually, two steps may be suggested, one that renders the tumor vessels susceptible to damage with subsequent hemorrhage, the second directly affecting the tumor cells. causing the cdl death. inhibi ting cdl growth, or with no effect. However the therapeutical application of cachectin in cancer is still at preliminary stages and requires further studies that eluciate better the mechanism of action of that cytokinc and eliminate most of its secondary toxicity..Inicialmente identificado pela actividade anti-tumoral, o Factor de Necrose Tumoral (TNF, de rumor necrosis factor) engloba, na realidade, dois tipos de polipeptidos (TNFa, ou caquexina, e o TNF J3, ou linfotoxina), com propriedades bioquímicas semelhantes a nível metabólico e imunitário. Estas substancias (reguladoras da inflamacao, da imunidade e defesa a agressão) pertencem a família das citocinas, intervindo como mediadores da intercomunicação celular. A caquexina e produzida como pro-hormona sendo activada por remoção de um péptido de 76 aminoacidos. A molécula activada (com 157 resíduos de aminoácidos) tem cerca de 28% da sua sequencia idêntica a da linfotoxina. Ambas as citocinas sao codificadas por genes diferentes (do cromossoma 6 no homem) e competem para receptores comuns. A caquexina e sintetizada por diversas celulas (fagocitarias e nao-fagocitarias) activadas. sobretudo pelos macrófagos. A biossíntese da caquexina e desencadeada por diversos estímulos (nomeadamente os lipopolissacaridos, das capsulas de bactérias Gram-negativas), apos o que a substancia em circulação interage com os receptores de elevada afinidade presentes nas membranas de tecidos normais, linhagens celulares transformadas ou células tumorais. A consequência da acção do TNFa (protecção ou lesão tecidual) dependem da concentração, duração da acção e presença de outros mediadores no ambiente celular. A caquexia (frequentemente associada a infeccoes graves e doencas tumorais) e atribuível a acção metabólica do TNFa. Esta citocina regula a actividade de diversas enzimas, aumentando o catabolismo lipídico (nas células adiposas) e o catabolismo glicidico (nos miocitos esqueleticos), a par da activação da gliconeogenese e biossíntese das proteínas da fase aguda (pelos hepatocitos). Uma das propriedades mais aliciantes da TNFa advém do seu potencial efeito na regressão tumoral, o que tem sido objecto de pesquisas intensas nos anos mais recentes. A caquexina induz a hemorragia e necrose tumoral por mecanismos ainda pouco esclarecidos. Este efeito poderia ser exercido a dois niveis: através de um intermediário desconhecido que lese as paredes vasculares (originando a hemorragia local), ou por actuação directa nas células tumorais (quer destruindo-as, inibindo-lhes o crescimento ou não tendo qualquer acção). No momento, a utilização terapêutica da TNF na doença tumoral e ainda limitada pelos seus principais efeitos secundário

Septic Shock Following Hysteroscopy. A Case Report

Introduction: Minimally invasive gynecological surgery such as hysteroscopy has a small risk of complications. These include uterine perforation (with or without adjacent pelvic organ lesion), bleeding and infection, and are more common in the presence of risk factors such as smoking, history of pelvic inflammatory disease (PID) and endometriosis. Case presentation: A patient submitted to a diagnostic hysteroscopy with no immediate complications was admitted five days later to the emergency department in septic shock. The diagnosis of ruptured tubal abscess was made, requiring emergency laparotomy with sub-total hysterectomy and bilateral adnexectomy. Despite multiple organ failure requiring admission to the intensive care unit, the patient made a full recovery. Conclusion: Ascending infection can be a life-threatening complication of hysteroscopy, even in the absence of previously known risk factors.info:eu-repo/semantics/publishedVersio

Erythrocyte filtrability and oxyhemoglobin dissociation in hypertensive patients

Twenty one patients with essential hypertension were studied. A significant decrease (p < 0.05) of hemoglobin oxygen affinity and a marked reduction (p < 0.001) of erythrocyte filtrability was detected. The results suggest an abnormality of the erythrocyte deformability in the microcirculation of the hypertensive patients, which implies a shift to the right of the oxyhemoglobin dissociation curve as a means of adaptation to the relative tissue hypoxia.This study was supported by a grant from INIC (MbL2)