461 research outputs found
A statistical comparison of the optical/UV and X-ray afterglows of gamma-ray bursts using the Swift Ultraviolet Optical and X-ray Telescopes
We present the systematic analysis of the Ultraviolet/Optical Telescope (UVOT) and X-ray Telescope (XRT) light curves for a sample of 26 Swift gamma-ray bursts (GRBs). By comparing the optical/UV and X-ray light curves, we found that they are remarkably different during the first 500 s after the Burst Alert Telescope trigger, while they become more similar during the middle phase of the afterglow, i.e. between 2000 and 20 000 s.
If we take literally the average properties of the sample, we find that the mean temporal indices observed in the optical/UV and X-rays after 500 s are consistent with a forward-shock scenario, under the assumptions that electrons are in the slow cooling regime, the external medium is of constant density and the synchrotron cooling frequency is situated between the optical/UV and X-ray observing bands. While this scenario describes well the averaged observed properties, some individual GRB afterglows require different or additional assumptions, such as the presence of late energy injection.
We show that a chromatic break (a break in the X-ray light curve that is not seen in the optical) is present in the afterglows of three GRBs and demonstrate evidence for chromatic breaks in a further four GRBs. The average properties of these breaks cannot be explained in terms of the passage of the synchrotron cooling frequency through the observed bands, nor a simple change in the external density. It is difficult to reconcile chromatic breaks in terms of a single component outflow and instead, more complex jet structure or additional emission components are required
Natural and human-induced Holocene paleoenvironmental changes on the Guadiana shelf (northern Gulf of Cadiz)
Three contrasting sedimentary environments on the continental shelf off the Guadiana River (northern Gulf of Cadiz) were integrated in a chronological framework and analysed in terms of sedimentology and benthic foraminiferal assemblages to understand the Holocene paleoenvironmental evolution. The analysed environments differ in terms of their depositional regimes and benthic foraminiferal assemblages. However, a dominant fluvial origin of the sand fraction was observed in all three environments. Holocene sedimentary processes were mainly controlled by natural (sea level changes and climate variations) and human-induced processes (e.g. deforestation, agriculture) along four evolutionary stages. The three older stages were mainly influenced by natural processes, such as sea level variations and fluvial inputs, whereas the most recent stage reflects a combination of climatic- and human-induced processes. A deepening of sedimentary environments related to a period of rapid sea level rise, strongly influenced by river discharges occurred from c. 11,500 to c. 10,000 cal. yr BP. A reduction in sediment export to the shelf, as a result of the continuous and rapid sea level rise and enhanced estuary infilling reflects the second stage, from c. 10,000 to c. 5000 cal. yr BP. The beginning of the third stage, from c. 5000 to c. 1500–1000 cal. yr BP, is marked by a sea-level slowdown and the relatively stable climate and environmental conditions. The fourth stage, from c. 1500–1000 cal. yr BP to Recent times, reflects the intensification of human-induced processes and climatic variability in the Guadiana River basin. This stage also reflects modern depositional conditions, with the formation of a proximal prodeltaic wedge and a distal muddy body
Evaluation of CD46 re-targeted adenoviral vectors for clinical ovarian cancer intraperitoneal therapy
Ovarian cancer accounts for >140 000 deaths globally each year. Typically, disease is asymptomatic until an advanced, incurable stage. Although response to cytotoxic chemotherapy is frequently observed, resistance to conventional platinum-based therapies develop rapidly. Improved treatments are therefore urgently required. Virotherapy offers great potential for ovarian cancer, where the application of local, intraperitoneal delivery circumvents some of the limitations of intravenous strategies. To develop effective, adenovirus (Ad)-based platforms for ovarian cancer, we profiled the fluid and cellular components of patient ascites for factors known to influence adenoviral transduction. Levels of factor X (FX) and neutralizing antibodies (nAbs) in ascitic fluid were quantified and tumor cells were assessed for the expression of coxsackie virus and adenovirus receptor (CAR) and CD46. We show that clinical ascites contains significant levels of FX but consistently high CD46 expression. We therefore evaluated in vitro the relative transduction of epithelial ovarian cancers (EOCs) by Ad5 (via CAR) and Ad5 pseudotyped with the fiber of Ad35 (Ad5T*F35++) via CD46. Ad5T*F35++ achieved significantly increased transduction in comparison to Ad5 (P<0.001), independent of FX and nAb levels. We therefore propose selective transduction of CD46 over-expressing EOCs using re-targeted, Ad35-pseudotyped Ad vectors may represent a promising virotherapy for ovarian cance
Nothing Lasts Forever: Environmental Discourses on the Collapse of Past Societies
The study of the collapse of past societies raises many questions for the theory and practice of archaeology. Interest in collapse extends as well into the natural sciences and environmental and sustainability policy. Despite a range of approaches to collapse, the predominant paradigm is environmental collapse, which I argue obscures recognition of the dynamic role of social processes that lie at the heart of human communities. These environmental discourses, together with confusion over terminology and the concepts of collapse, have created widespread aporia about collapse and resulted in the creation of mixed messages about complex historical and social processes
A New NO-Releasing Nanoformulation for the Treatment of Pulmonary Arterial Hypertension.
Pulmonary arterial hypertension (PAH) is a chronic and progressive disease which continues to carry an unacceptably high mortality and morbidity. The nitric oxide (NO) pathway has been implicated in the pathophysiology and progression of the disease. Its extremely short half-life and systemic effects have hampered the clinical use of NO in PAH. In an attempt to circumvent these major limitations, we have developed a new NO-nanomedicine formulation. The formulation was based on hydrogel-like polymeric composite NO-releasing nanoparticles (NO-RP). The kinetics of NO release from the NO-RP showed a peak at about 120 min followed by a sustained release for over 8 h. The NO-RP did not affect the viability or inflammation responses of endothelial cells. The NO-RP produced concentration-dependent relaxations of pulmonary arteries in mice with PAH induced by hypoxia. In conclusion, NO-RP drugs could considerably enhance the therapeutic potential of NO therapy for PAH
Glycogen Utilization during Running: Intensity, Sex, and Muscle-specific Responses.
PURPOSE: To quantify net glycogen utilisation in the vastus lateralis (VL) and gastrocnemius (G) of male (n=11) and female (n=10) recreationally active runners during three outdoor training sessions. METHODS: After 2 days standardisation of carbohydrate (CHO) intakes (6 g.kg body mass per day), glycogen was assessed before and after 1) a 10-mile road run (10-mile) at lactate threshold, 2) 8 x 800 m track intervals (8 x 800 m) at velocity at V[Combining Dot Above]O2max and 3) 3 x 10 minute track intervals (3 x 10 min) at lactate turnpoint. RESULTS: Resting glycogen concentration was lower in the G of females compared with males (P0.05). Net glycogen utilisation was greater in males than females in both VL (P=0.02) and G (P=0.07) during the 10-mile road run. With the exception of males during the 3 x 10 min protocol (P=0.28), greater absolute glycogen utilisation was observed in the G versus the VL muscle in both males and females and during all training protocols (all comparisons, P<0.05). CONCLUSION: Data demonstrate 1) prolonged steady state running necessitates a greater glycogen requirement than shorter but higher intensity track running sessions, 2) females display evidence of reduced resting muscle glycogen concentration and net muscle glycogen utilisation when compared with males and 3), net glycogen utilisation is higher in the gastrocnemius muscle compared with the vastus lateralis
A ‘modified de Gramont’ regimen of fluorouracil, alone and with oxaliplatin, for advanced colorectal cancer
The standard de Gramont (dG) regimen of fortnightly leucovorin, bolus fluorouracil and 22-h infusion of fluorouracil, d1+2, and the same regimen plus oxaliplatin, are effective but also cumbersome. We therefore present simplified ‘Modified de Gramont’ (MdG) regimens. Forty-six advanced gastrointestinal cancer patients entered a dose-exploring study of MdG, including an expanded cohort of colorectal cancer patients at optimum dose. Treatment (fortnightly) comprised: 2-h i.v.i. leucovorin (350 mg d,l-LV or 175 mg l-LV, not adjusted for patient surface area); bolus fluorouracil (400 mg m−2), then ambulatory 46-h fluorouracil infusion (2000–3600 mg m−2, cohort escalation). Subsequently, 62 colorectal patients (25 unpretreated; 37 fluorouracil-resistant) received MdG plus oxaliplatin (OxMdG) 85 mg m−2. Fluorouracil pharmacokinetics during MdG were compared with dG. The optimum fluorouracil doses for MdG alone were determined as 400 mg m−2 bolus + 2800 mg m−2 46-h infusion. A lower dose of 400 mg m−2 bolus + 2400 mg m−2 infusion which, like dG produces minimal toxicity, was chosen for the OxMdG combination. Fluorouracil exposure (AUC0–48 h) at this lower dose is equivalent to dG. With OxMdG, grade 3–4 toxicity was rare (neutropenia 2.8% cycles; vomiting or diarrhoea <1% cycles), but despite this there were two infection-associated deaths. Oxaliplatin was omitted for cumulative neurotoxicity in 17 out of 62 patients. Objective responses in colorectal cancer patients were: 1st-line MdG (22 assessable): PR=36%, NC=32%, PD=32%. 1st-line OxMdG (24 assessable): CR/PR=72%; NC=20%; PD=8%; 2nd line OxMdG (34 assessable): PR=12%; NC=38%; PD=50%. MdG and OxMdG are convenient and well-tolerated. OxMdG was particularly active as 1st-line treatment of advanced colorectal cancer. Both regimens are being further evaluated in the current UK MRC phase III trial
Effects of different sources of carbohydrates on intake, digestibility, chewing, and performance of Holstein dairy cows
Genome-level homology and phylogeny of Shewanella (Gammaproteobacteria: lteromonadales: Shewanellaceae)
<p>Abstract</p> <p>Background</p> <p>The explosion in availability of whole genome data provides the opportunity to build phylogenetic hypotheses based on these data as well as the ability to learn more about the genomes themselves. The biological history of genes and genomes can be investigated based on the taxomonic history provided by the phylogeny. A phylogenetic hypothesis based on complete genome data is presented for the genus <it>Shewanella </it>(Gammaproteobacteria: Alteromonadales: Shewanellaceae). Nineteen taxa from <it>Shewanella </it>(16 species and 3 additional strains of one species) as well as three outgroup species representing the genera <it>Aeromonas </it>(Gammaproteobacteria: Aeromonadales: Aeromonadaceae), <it>Alteromonas </it>(Gammaproteobacteria: Alteromonadales: Alteromonadaceae) and <it>Colwellia </it>(Gammaproteobacteria: Alteromonadales: Colwelliaceae) are included for a total of 22 taxa.</p> <p>Results</p> <p>Putatively homologous regions were found across unannotated genomes and tested with a phylogenetic analysis. Two genome-wide data-sets are considered, one including only those genomic regions for which all taxa are represented, which included 3,361,015 aligned nucleotide base-pairs (bp) and a second that additionally includes those regions present in only subsets of taxa, which totaled 12,456,624 aligned bp. Alignment columns in these large data-sets were then randomly sampled to create smaller data-sets. After the phylogenetic hypothesis was generated, genome annotations were projected onto the DNA sequence alignment to compare the historical hypothesis generated by the phylogeny with the functional hypothesis posited by annotation.</p> <p>Conclusions</p> <p>Individual phylogenetic analyses of the 243 locally co-linear genome regions all failed to recover the genome topology, but the smaller data-sets that were random samplings of the large concatenated alignments all produced the genome topology. It is shown that there is not a single orthologous copy of 16S rRNA across the taxon sampling included in this study and that the relationships among the multiple copies are consistent with 16S rRNA undergoing concerted evolution. Unannotated whole genome data can provide excellent raw material for generating hypotheses of historical homology, which can be tested with phylogenetic analysis and compared with hypotheses of gene function.</p
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