983 resultados para Victor Mercante


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A complete nucleotide sequence of the new Pseudomonas aeruginosa Luz24likevirus phiCHU was obtained. This virus was shown to have a unique host range whereby it grew poorly on the standard laboratory strain PAO1, but infected 26 of 46 clinical isolates screened, and strains harboring IncP2 plasmid pMG53. It was demonstrated that phiCHU has single strand interruptions in its genome. Analysis of the phiCHU genome also suggested that recombination event(s) participated in the evolution of the leftmost portion of the genome, presumably encoding early genes.

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Biodiversity continues to decline in the face of increasing anthropogenic pressures such as habitat destruction, exploitation, pollution and introduction of alien species. Existing global databases of species' threat status or population time series are dominated by charismatic species. The collation of datasets with broad taxonomic and biogeographic extents, and that support computation of a range of biodiversity indicators, is necessary to enable better understanding of historical declines and to project - and avert - future declines. We describe and assess a new database of more than 1.6 million samples from 78 countries representing over 28,000 species, collated from existing spatial comparisons of local-scale biodiversity exposed to different intensities and types of anthropogenic pressures, from terrestrial sites around the world. The database contains measurements taken in 208 (of 814) ecoregions, 13 (of 14) biomes, 25 (of 35) biodiversity hotspots and 16 (of 17) megadiverse countries. The database contains more than 1% of the total number of all species described, and more than 1% of the described species within many taxonomic groups - including flowering plants, gymnosperms, birds, mammals, reptiles, amphibians, beetles, lepidopterans and hymenopterans. The dataset, which is still being added to, is therefore already considerably larger and more representative than those used by previous quantitative models of biodiversity trends and responses. The database is being assembled as part of the PREDICTS project (Projecting Responses of Ecological Diversity In Changing Terrestrial Systems - http://www.predicts.org.uk). We make site-level summary data available alongside this article. The full database will be publicly available in 2015.

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Herein, the N-butyl-N-methylpyrrolidinium bis(fluorosulfonyl)amide and the N-propyl-N-methylpyrrolidinium bis(fluorosulfonyl)amide room temperature ionic liquids, combined with the lithium bis(trifluoromethanesulfonyl)amide salt, are investigated as electrolytes for Li/LiNi1/3Mn1/3Co1/3O2 (Li/NMC) batteries. To conduct this study, volumetric properties, ionic conductivity and viscosity of the pure ionic liquids and selected electrolytes were firstly determined as a function of temperature and composition in solution. These data were then compared with those measured in the case of the standard alkyl carbonate-based electrolyte: e.g. the EC/PC/3DMC + 1 mol·L−1 LiPF6. The compatibility of the selected electrolytes with the lithium electrode was then investigated by following the evolution of Li/electrolyte interfaces through impedance measurements. Interestingly, the impedances of the investigated Li/electrolyte interfaces were found to be more than three times lower than that measured using the standard electrolyte. Finally, electrochemical performances of the ionic liquid-based electrolytes were investigated using galvanostatic charge and discharge and cyclic voltammetry of each Li/NMC cell. Using these electrolytes, each tested Li cell reaches up to 145 mA·h·g−1 at C/10 and 110 mA·h·g−1 at C with a coulombic efficiency close to 100 %.

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Polyacetylenes of the falcarinol type such as falcarinol and falcarindiol naturally occur in plants of the Apiaceae family, mainly carrots and parsnips. In extracts of newly harvested carrots and parsnips, their levels vary between 20 and 300 mg/kg fresh weight and depend on agronomic factors, in particular the cultivar type. With increasing evidence of their in vitro bioactivity, the retention of these heat-sensitive compounds is desirable during handling, processing, and storage of carrots and parsnips. Quantification of these compounds is usually performed using reverse-phase chromatography coupled with mass spectrometry or other detection methods after appropriate solvent extraction. During minimal processing most losses occur during peeling of the carrots due to the higher distribution of polyacetylenes in the vegetable skin. Heat processing results in reduction of polyacetylene levels, whereas in the case of non-thermal processing, it is mainly dependent on the method employed. The levels of polyacetylenes are rather stable during short-term storage. There are some general guidelines to ensure higher retention of polyacetylene.

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Virgin olive oil is a high quality natural product obtained only by physical means. In addition to triacylglycerols it contains nutritionally important polar and non-polar antioxidant phenols and other bioactive ingredients. The polar fraction is a complex mixture of phenolic acids, simple phenols, derivatives of the glycosides oleuropein and ligstroside, lignans, and flavonoids. These compounds contribute significantly to the stability, flavor, and biological value of virgin olive. In the various stages of production, during storage and in the culinary uses, polar phenols and other valuable bioactive ingredients may be damaged. Oxidation, photo-oxidation, enzymic hydrolysis and heating at frying temperatures have a serious adverse effect. Due to the biological importance of the oil and its unique character, analytical methods have been developed to evaluate antioxidant activity or analyse complex phenol mixtures. These are based on radical scavenging assays and chromatographic techniques. Hyphenated methods are also used including liquid chromatography-mass spectrometry and liquid chromatography-nuclear magnetic resonance spectroscopy.

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Introduction: Because a dose–response relationship is characteristic of conventional chemotherapy, this concept is widely used for the development of novel cytotoxic (CTX) drugs. However, the need to reach the MTD to obtain optimal benefit with molecularly targeted agents (MTA) is controversial. In this study, we evaluated the relationship between dose and efficacy in a large cohort of phase I patients with solid tumors.

Experimental Design: We collected data on 1,182 consecutive patients treated in phase I trials in 14 European institutions in 2005–2007. Inclusion criteria were: (i) patients treated within completed single-agent studies in which a maximum-administered dose was defined and (ii) RECIST/survival data available.

Results: Seventy-two percent of patients were included in trials with MTA (N = 854) and 28% in trials with CTX (N = 328). The objective response (OR) rate was 3% and disease control at 6 months was 11%. OR for CTX was associated with higher doses (median 92% of MTD); this was not the case for MTA, where patients achieving OR received a median of 50% of MTD. For trials with MTA, patients treated at intermediate doses (40%–80%) had better survival compared with those receiving low or high doses (P = 0.038). On the contrary, there was a direct association between higher dose and better OS for CTX agents (P = 0.003).

Conclusion: Although these results support the development of novel CTX based on MTD, we found no direct relationship between higher doses and response with MTA in unselected patients. However, the longest OS was seen in patients treated with MTA at intermediate doses (40%–80% of MTD)

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Recent research in Europe, Africa, and Southeast Asia suggests that we can no longer assume a direct and exclusive link between anatomically modern humans and behavioral modernity (the 'human revolution'), and assume that the presence of either one implies the presence of the other: discussions of the emergence of cultural complexity have to proceed with greater scrutiny of the evidence on a site-by-site basis to establish secure associations between the archaeology present there and the hominins who created it. This paper presents one such case study: Niah Cave in Sarawak on the island of Borneo, famous for the discovery in 1958 in the West Mouth of the Great Cave of a modern human skull, the 'Deep Skull,' controversially associated with radiocarbon dates of ca. 40,000 years before the present. A new chronostratigraphy has been developed through a re-investigation of the lithostratigraphy left by the earlier excavations, AMS-dating using three different comparative pre-treatments including ABOX of charcoal, and U-series using the Diffusion-Absorption model applied to fragments of bones from the Deep Skull itself. Stratigraphic reasons for earlier uncertainties about the antiquity of the skull are examined, and it is shown not to be an `intrusive' artifact. It was probably excavated from fluvial-pond-desiccation deposits that accumulated episodically in a shallow basin immediately behind the cave entrance lip, in a climate that ranged from times of comparative aridity with complete desiccation, to episodes of greater surface wetness, changes attributed to regional climatic fluctuations. Vegetation outside the cave varied significantly over time, including wet lowland forest, montane forest, savannah, and grassland. The new dates and the lithostratigraphy relate the Deep Skull to evidence of episodes of human activity that range in date from ca. 46,000 to ca. 34,000 years ago. Initial investigations of sediment scorching, pollen, palynomorphs, phytoliths, plant macrofossils, and starch grains recovered from existing exposures, and of vertebrates from the current and the earlier excavations, suggest that human foraging during these times was marked by habitat-tailored hunting technologies, the collection and processing of toxic plants for consumption, and, perhaps, the use of fire at some forest-edges. The Niah evidence demonstrates the sophisticated nature of the subsistence behavior developed by modern humans to exploit the tropical environments that they encountered in Southeast Asia, including rainforest. (c) 2006 Elsevier Ltd. All rights reserved.

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The paper describes the initial results from renewed investigations at Niah Cave in Sarawak on the island of Borneo, famous for the discovery in 1958 of the c. 40,000-year old 'Deep Skull'. The archaeological sequences from the West Mouth and the other entrances of the cave complex investigated by Tom and Barbara Harrisson and other researchers have potential implications for three major debates regarding the prehistory of south-east Asia: the timing of initial settlement by anatomically modern humans; the means by which they subsisted in the late Pleistocene and early Holocene; and the timing, nature, and causation of the transition from foraging to farming. The new project is informing on all three debates. The critical importance of the Niah stratigraphies was commonly identified - including by Tom Harrisson himself - as because the site provided a continuous sequence of occupation over the past 40,000 years. The present project indicates that Niah was first used at least 45,000 years ago, and probably earlier; that the subsequent Pleistocene and Holocene occupations were highly variable in intensity and character; and that in some periods, perhaps of significant duration, the caves may have been more or less abandoned. The cultural sequence that is emerging from the new investigations may be more typical of cave use in tropical rainforests in south-east Asia than the Harrisson model.