925 resultados para Phase rule and equilibrium
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Tese de doutoramento (co-tutela), Geologia (Paleontologia e Estratigrafia), Faculdade de Ciências da Universidade de Lisboa, Université Claude Bernard Lyon 1, 2016
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Tese de doutoramento, Psicologia (Psicologia Clínica), Universidade de Lisboa, Faculdade de Psicologia, 2016
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The chick chorioallantoic membrane (CAM) is a widely used model for the study of angiogenesis, tumour growth, as well as drug efficacy. In spite of this, little is known about the developmental alteration from its appearance to the time of hatching. In the current study the CAM has been studied by classical stereology and allometry. Expression levels of selected angiogenesis-related molecules were estimated by RT-PCR and cell dynamics assessed by proliferation and apoptosis assays. Absolute CAM volume increased from a low of 0.47 ± 0.11 cm3 at embryonic day 8 (E8) to a high of 2.05 ± 0.27 cm3 at E18, and then decreased to 1.6 ± 0.47 cm3 at E20. On allometric analysis, three growth phases were identifiable. Between E8-13 (phase I), the CAM grew fastest; moderately in phase II (E13-18) but was regressing in phase III (E18-20). The chorion, the mesenchyme and the allantoic layers grew fastest in phase I, but moderately in phase II. The mesenchyme grew slowly in phase III while the chorion and allantois were regressing. Chorionic cell volume increased fastest in phase I and was regressing in phase III. Chorionic capillaries grew steadily in phase I and II but regressed in phase III. Both the chorion and the allantois grew by intrinsic cell proliferation as well as recruitment of cells from the mesenchyme. Cell proliferation was prominent in the allantois and chorion early during development, declined after E17 and apoptosis started mainly in the chorion from E14. VEGFR2 expression peaked at E11 and declined steadily towards E20, VEGF peaked at E13 and E20 while HIF 1α had a peak at E11 and E20. Studies targeting CAM growth and angiogenesis need to take these growth phases into consideration.
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Background Image-guided systems have recently been introduced for their application in liver surgery.We aimed to identify and propose suitable indications for image-guided navigation systems in the domain of open oncologic liver surgery and,more specifically, in the setting of liver resection with and without microwave ablation. Method Retrospective analysis was conducted in patients undergoing liver resection with and without microwave ablation using an intraoperative image-guided stereotactic system during three stages of technological development (accuracy: 8.4 ± 4.4 mm in phase I and 8.4 ± 6.5 mm in phase II versus 4.5 ± 3.6 mm in phase III). It was evaluated, in which indications image-guided surgery was used according to the different stages of technical development. Results Between 2009 and 2013, 65 patients underwent image-guided surgical treatment, resection alone (n=38), ablation alone (n =11), or a combination thereof (n =16). With increasing accuracy of the system, image guidance was progressively used for atypical resections and combined microwave ablation and resection instead of formal liver resection (p<0.0001). Conclusion Clinical application of image guidance is feasible, while its efficacy is subject to accuracy. The concept of image guidance has been shown to be increasingly efficient for selected indications in liver surgery. While accuracy of available technology is increasing pertaining to technological advancements, more and more previously untreatable scenarios such as multiple small, bilobar lesions and so-called vanishing lesions come within reach.
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The Indian Summer Monsoon (ISM) is an inter-hemispheric and highly variable ocean-atmosphere-land interaction that directly affects the densely populated Indian subcontinent. Here, we present new records of palaeoceanographic variability that span the last 500,000 years from the eastern equatorial Indian Ocean, a relatively under-sampled area of ISM influence. We have generated carbon and oxygen stable isotope records from three foraminiferal species from Ocean Drilling Program Site 758 (5°N, 90°E) to investigate the oceanographic history of this region. We interpret our resultant Dd18O (surface-thermocline) record of upper water-column stratification in the context of past ISM variability, and compare orbital phase relationships in our Site 758 data to other climate and monsoon proxies in the region. Results suggest that upper water-column stratification at Site 758, which is dominated by variance at precession and half-precession frequencies (23, 19 and 11 ka), is forced by both local (5°N) insolation and ISM winds. In the precession (23 ka) band, stratification minima at Site 758 lag northern hemisphere summer insolation maxima (precession minima) by 9 ka, which is consistent with Arabian Sea ISM phase estimates and suggests a common wind forcing in both regions. This phase implicates a strong sensitivity to both ice volume and southern hemisphere insolation forcing via latent heat export from the southern subtropical Indian Ocean. Additionally, we find evidence of possible overprinting of millennial-scale events during glacial terminations in our stratification record, which suggests an influence of remote abrupt climate events on ISM dynamics.
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The present study investigates the concentrations and patterns of organochlorine pesticides (OCPs) and their metabolites in liver and plasma of two ringed seal populations (Phoca hispida): lower contaminated Svalbard population and more contaminated Baltic Sea population. Among OCPs, p,p'-DDE and sum-chlordanes were the highest in concentration. With increasing hepatic contaminant concentrations and activities of xenobiotic-metabolizing enzymes, the concentrations of 3-methylsulfonyl-p,p'-DDE and the concentration ratios of pentachlorophenol/hexachlorobenzene increased, and the toxaphene pattern shifted more towards persistent Parlar-26 and -50 and less towards more biodegradable Parlar-44. Relative concentrations of the chlordane metabolites, oxychlordane and -heptachlorepoxide, to sum-chlordanes were higher in the seals from Svalbard compared to the seals from the Baltic, while the trend was opposite for cis- and trans-nonachlor. The observed differences in the OCP patterns in the seals from the two populations are probably related to the catalytic activity of xenobiotic-metabolizing enzymes, and also to differences in dietary exposure.
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Planktic foraminiferal census data, faunal sea surface temperatures (SSTs) and oxygen isotopic and lithic records from a site in the northeast Atlantic were analyzed to study the interglacial dynamics of Marine Isotope Stage (MIS) 11, a period thought to closely resemble the Holocene on the basis of orbital forcing. Interglacial conditions during MIS 11 persisted for approximately 26 ka. After the main deglacial meltwater processes ceased, a 10- to 12-ka-long transitional period marked by significant water mass circulation changes occurred before surface waters finally reached their thermal maximum. This SST peak occurred between 400 and 397 ka, inferred from the abundance of the most thermophilic foraminiferal species and was coincident with lowest sea level according to benthic isotope values. The ensuing stepwise SST decrease characterizes the overall climate deterioration preceding the increase in global ice volume by ab. 3 ka. This cooling trend was followed by a more pronounced cold event that began at 388 ka, and that terminated in the recurrence of icebergs at the site around 382 ka. Because the water mass configuration of early MIS 11 evolved quite differently from that of the early Holocene, there is little evidence that MIS 11 can serve as an appropriate analogue for a future Holocene climate, despite the similarity in some orbital parameters.
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After the electoral reform in 1994, Japan saw a gradual evolution from a multi-party system toward a two-party system over the course of five House of Representatives election cycles. In contrast, after Taiwan’s constitutional amendment in 2005, a two-party system emerged in the first post-reform legislative election in 2008. Critically, however, Taiwan’s president is directly elected while Japan’s prime minister is indirectly elected. The contributors conclude that the higher the payoffs of holding the executive office and the greater degree of cross-district coordination required to win it, the stronger the incentives for elites to form and stay in the major parties. In such a context, a country will move rapidly toward a two-party system. In Part II, the contributors apply this theoretical logic to other countries with mixed-member systems to demonstrate its generality. They find the effect of executive competition on legislative electoral rules in countries as disparate as Thailand, the Philippines, New Zealand, Bolivia, and Russia. The findings presented in this book have important implications for political reform. Often, reformers are motivated by high hopes of solving some political problems and enhancing the quality of democracy. But, as this group of scholars demonstrates, electoral reform alone is not a panacea. Whether and to what extent it achieves the advocated goals depends not only on the specification of new electoral rules per se but also on the political context—and especially the constitutional framework—within which such rules are embedded.
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Mode of access: Internet.
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CONTENTS. - A model village of homes. - An English half-holiday. - Stage-coaching in England. - Coffee-houses in Great-Britain. - The Sunday-school centenary, London. - A fete of the French republic. - A visit to the World's Columbian exposition, Chicago. - The Great Lakes and the Mediterranean. - Spanish rule, and its end, in Cuba. - A college vacation at the front. - How fine papers are manufactured. - Entertainments for the people. - The flags of all nations.
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Photocopy.
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This work reports the first instance of self-organized thermoset blends containing diblock copolymers with a crystallizable thermoset-immiscible block. Nanostructured thermoset blends of bisphenol A-type epoxy resin (ER) and a low-molecular-weight (M-n = 1400) amphiphilic polyethylene-block-poly(ethylene oxide) (EEO) symmetric diblock copolymer were prepared using 4,4'-methylenedianiline (MDA) as curing agent and were characterized by transmission electron microscopy (TEM), atomic force microscopy (AFM), small-angle X-ray scattering (SAXS), and differential scanning calorimetry (DSC). All the MDA-cured ER/EEO blends do not show macroscopic phase separation but exhibit microstructures. The ER selectively mixes with the epoxy-miscible PEO block in the EEO diblock copolymer whereas the crystallizable PE blocks that are immiscible with ER form separate microdomains at nanoscales in the blends. The PE crystals with size on nanoscales are formed and restricted within the individual spherical micelles in the nanostructured ER/EEO blends with EEO content up to 30 wt %. The spherical micelles are highly aggregated in the blends containing 40 and 50 wt % EEO. The PE dentritic crystallites exist in the blend containing 50 wt % EEO whereas the blends with even higher EEO content are completely volume-filled with PE spherulites. The semicrystalline microphase-separated lamellae in the symmetric EEO diblock copolymer are swollen in the blend with decreasing EEO content, followed by a structural transition to aggregated spherical micellar phase morphology and, eventually, spherical micellar phase morphology at the lowest EEO contents. Three morphological regimes are identified, corresponding precisely to the three regimes of crystallization kinetics of the PE blocks. The nanoscale confinement effect on the crystallization kinetics in nanostructured thermoset blends is revealed for the first time. This new phenomenon is explained on the basis of homogeneous nucleation controlled crystallization within nanoscale confined environments in the block copolymer/thermoset blends.
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This study aimed to identify potential factors responsible for geographically structured morphological variation within the widespread Australian frogs Limnodynastes tasmaniensis Gunther and L. peronii Dumeril & Bibron. There was support for James's rule, and both latitude and present climate explained large amounts of the variation in body size and shape (particularly in L. peronii). There was also some support for the influence of several biogeographical barriers. Finally, both species were sexually dimorphic for body size and the degree of sexual size dimorphism (SSD) varied geographically. Climate was an important explanation for SSD variation in L. peronii, while latitude was most important for L. tasmaniensis. Geographical variations in sexual selection via male-male physical competition and climate-related resources are suggested as potential explanations for SSD variation in L. peronii. (C) 2004 The Linnean Society of London.
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One common characteristic of breast cancers arising in carriers of the predisposition gene BRCA1 is a loss of expression of the CDK inhibitor p27(Kip1) (p27), suggesting that p27 interacts epistatically with BRCA1. To investigate this relationship, we examined expression of p27 in mice expressing a dominant negative allele of Brca1 (MMTV-trBr) in the mammary gland. While these mice rarely develop tumors, they showed a 50% increase in p27 protein and a delay in mammary gland development associated with reduced proliferation. In contrast, on a p27 heterozygote background, MMTV-trBrca1 mice showed an increase in S phase cells, and normal mammary development. p27 was the only protein in the cyclin cyclin-dependent kinase network to show altered expression, suggesting that it may be a central mediator of cell cycle arrest in response to loss of function of BRCA1. Furthermore, in human mammary epithelial MCF7 cells expressing BRCA1-specific RNAi and in the BRCA1-deficient human tumor cell line HCC1937, p27 is elevated at the mRNA level compared to cells expressing wild-type BRCA1. We hypothesize that disruption of BRCA1 induces an increase in p27 that inhibits proliferation. Accordingly, reduction in p27 expression leads to enhancement of cellular proliferation in the absence of BRCA1.