700 research outputs found

    Analysis of noise in the Rookhope area

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    The main purpose of this research has been to investigate the attenuation and frequency characteristics of noise generated by a single source. About seven weeks were spent from October to late November, 1963 measuring the vertical ground velocity of the noise over a network of recording stations on the southern slopes of the valley at Rookhope, County Durham. Special recording methods were used to eliminate the effects of any variation in noise level with time. This was necessary as the ground velocity at all stations over the network had to be normalised to values that would be obtained for a constant source, before they could be used in the construction of attenuation curves. Two methods of frequency analysis were performed on a number of the station records: one a power spectral analysis using a computer to facilitate calculations, and the other employing a range of band-pass filters on records obtained on magnetic tape. Both techniques showed that the noise consisted essentially of two frequency components, 6 c.p.s. and 11-12 c.p.s., the latter being confined to an area in the immediate vicinity of the source. Attenuation analyses revealed the presence of two areas to the west and south of the source which showed noticeably different rates of attenuation. Two possible hypotheses were put forward to explain this phenomenon: one embodying a change in subsurface conditions between the two areas, and the other constant subsurface conditions, but a change in the predominant wave types propagating over the two regions. Since no knowledge could be obtained on the precise distribution and nature of the wave types, as the vertical ground velocity only was measured, both theories were considered to be open to some doubt, and thus preference was given to neither. It was found that the values of the rate of absorption obtained for the two areas were generally consistent with those usually found from laboratory experiments on sedimentary rocks

    Do selective cyclo-oxygenase-2 inhibitors and traditional non-steroidal anti-inflammatory drugs increase the risk of atherothrombosis? Meta-analysis of randomised trials

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    Objective: To assess the effects of selective cyclo-oxygenase-2 (COX 2) inhibitors and traditional non-steroidal anti-inflammatory drugs (NSAIDs) on the risk of vascular events. Design: Meta-analysis of published and unpublished tabular data from randomised trials, with indirect estimation of the effects of traditional NSAIDs. Data sources: Medline and Embase (January 1966 to April 2005); Food and Drug Administration records; and data on file from Novartis, Pfizer, and Merck. Review methods: Eligible studies were randomised trials that included a comparison of a selective COX 2 inhibitor versus placebo or a selective COX 2 inhibitor versus a traditional NSAID, of at least four weeks' duration, with information on serious vascular events (defined as myocardial infarction, stroke, or vascular death). Individual investigators and manufacturers provided information on the number of patients randomised, numbers of vascular events, and the person time of follow-up for each randomised group. Results: In placebo comparisons, allocation to a selective COX 2 inhibitor was associated with a 42% relative increase in the incidence of serious vascular events (1.2%/year v 0.9%/year; rate ratio 1.42, 95% confidence interval 1.13 to 1.78; P = 0.003), with no significant heterogeneity among the different selective COX 2 inhibitors. This was chiefly attributable to an increased risk of myocardial infarction (0.6%/year v 0.3%/year; 1.86, 1.33 to 2.59; P = 0.0003), with little apparent difference in other vascular outcomes. Among trials of at least one year's duration (mean 2.7 years), the rate ratio for vascular events was 1.45 (1.12 to 1.89; P = 0.005). Overall, the incidence of serious vascular events was similar between a selective COX 2 inhibitor and any traditional NSAID (1.0%/year v 0.9/%year; 1.16, 0.97 to 1.38; P = 0.1). However, statistical heterogeneity (P = 0.001) was found between trials of a selective COX 2 inhibitor versus naproxen (1.57, 1.21 to 2.03) and of a selective COX 2 inhibitor versus non-naproxen NSAIDs (0.88, 0.69 to 1.12). The summary rate ratio for vascular events, compared with placebo, was 0.92 (0.67 to 1.26) for naproxen, 1.51 (0.96 to 2.37) for ibuprofen, and 1.63 (1.12 to 2.37) for diclofenac. Conclusions: Selective COX 2 inhibitors are associated with a moderate increase in the risk of vascular events, as are high dose regimens of ibuprofen and diclofenac, but high dose naproxen is not associated with such an excess

    Water requirements of floodplain rivers and fisheries: existing decision support tools and pathways for development

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    Fisheries / Rivers / Flood plains / Hydrology / Ecology / Models / Decision support tools / Environmental impact assessment / Methodology / Databases

    Theory of Electric Field-Induced Photoluminescence Quenching in Disordered Molecular Solids

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    The dynamics of excitons in disordered molecular solids is studied theoretically, taking into account migration between different sites, recombination, and dissociation into free charge carriers in the presence of an electric field. The theory is applied to interpret the results of electric field-induced photoluminescence (PL) quenching experiments on molecularly doped polymers by Deussen et al. [Chem. Phys. 207, 147 (1996)]. Using an intermolecular dissociation mechanism, the dependence of the PL quenching on the electric field strength and the dopant concentration, and the time evolution of the transient PL quenching can be well described. The results constitute additional proof of the distinct exciton dissociation mechanisms in conjugated polymer blends and molecularly doped polymers.Comment: 4 pages RevTeX, 3 Postscript figure

    Effects of gastroprotectant drugs for the prevention and treatment of peptic ulcer disease and its complications: a meta-analysis of randomised trials

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    Background: Gastroprotectant drugs are used for the prevention and treatment of peptic ulcer disease and might reduce its associated complications, but reliable estimates of the effects of gastroprotectants in different clinical settings are scarce. We aimed to examine the effects of proton-pump inhibitors (PPIs), prostaglandin analogues, and histamine-2 receptor antagonists (H2RAs) in different clinical circumstances by doing meta-analyses of tabular data from all relevant unconfounded randomised trials of gastroprotectant drugs. Background: Gastroprotectant drugs are used for the prevention and treatment of peptic ulcer disease and might reduce its associated complications, but reliable estimates of the effects of gastroprotectants in different clinical settings are scarce. We aimed to examine the effects of proton-pump inhibitors (PPIs), prostaglandin analogues, and histamine-2 receptor antagonists (H2RAs) in different clinical circumstances by doing meta-analyses of tabular data from all relevant unconfounded randomised trials of gastroprotectant drugs. Methods: We searched MEDLINE and Embase from Jan 1, 1950, to Dec 31, 2015, to identify unconfounded, randomised trials of a gastroprotectant drug (defined as a PPI, prostaglandin analogue, or H2RA) versus control, or versus another gastroprotectant. Two independent researchers reviewed the search results and extracted the prespecified outcomes and key characteristics for each trial. We did meta-analyses of the effects of gastroprotectant drugs on ulcer development, bleeding, and mortality overall, according to the class of gastroprotectant, and according to the individual drug within a gastroprotectant class. Findings: We identified comparisons of gastroprotectant versus control in 849 trials (142 485 participants): 580 prevention trials (110 626 participants), 233 healing trials (24 033 participants), and 36 trials for the treatment of acute upper gastrointestinal bleeding (7826 participants). Comparisons of one gastroprotectant drug versus another were available in 345 trials (64 905 participants), comprising 160 prevention trials (32 959 participants), 167 healing trials (28 306 participants), and 18 trials for treatment of acute upper gastrointestinal bleeding (3640 participants). The median number of patients in each trial was 78 (IQR 44Ā·0ā€“210Ā·5) and the median duration was 1Ā·4 months (0Ā·9ā€“2Ā·8). In prevention trials, gastroprotectant drugs reduced development of endoscopic ulcers (odds ratio [OR] 0Ā·27, 95% CI 0Ā·25ā€“0Ā·29; p<0Ā·0001), symptomatic ulcers (0Ā·25, 0Ā·22ā€“0Ā·29; p<0Ā·0001), and upper gastrointestinal bleeding (0Ā·40, 0Ā·32ā€“0Ā·50; p<0Ā·0001), but did not significantly reduce mortality (0Ā·85, 0Ā·69ā€“1Ā·04; p=0Ā·11). Larger proportional reductions in upper gastrointestinal bleeding were observed for PPIs than for other gastroprotectant drugs (PPIs 0Ā·21, 99% CI 0Ā·12ā€“0Ā·36; prostaglandin analogues 0Ā·63, 0Ā·35ā€“1Ā·12; H2RAs 0Ā·49, 0Ā·30ā€“0Ā·80; phet=0Ā·0005). Gastroprotectant drugs were effective in preventing bleeding irrespective of the use of non-steroidal anti-inflammatory drugs (phet=0Ā·56). In healing trials, gastroprotectants increased endoscopic ulcer healing (3Ā·49, 95% CI 3Ā·28ā€“3Ā·72; p<0Ā·0001), with PPIs more effective (5Ā·22, 99% CI 4Ā·00ā€“6Ā·80) than prostaglandin analogues (2Ā·27, 1Ā·91ā€“2Ā·70) and H2RAs (3Ā·80, 3Ā·44ā€“4Ā·20; phet<0Ā·0001). In trials among patients with acute bleeding, gastroprotectants reduced further bleeding (OR 0Ā·68, 95% CI 0Ā·60ā€“0Ā·78; p<0Ā·0001), blood transfusion (0Ā·75, 0Ā·65ā€“0Ā·88; p=0Ā·0003), further endoscopic intervention (0Ā·56, 0Ā·45ā€“0Ā·70; p<0Ā·0001), and surgery (0Ā·72, 0Ā·61ā€“0Ā·84; p<0Ā·0001), but did not significantly reduce mortality (OR 0Ā·90, 0Ā·72ā€“1Ā·11; p=0Ā·31). PPIs had larger protective effects than did H2RAs for further bleeding (phet=0Ā·0107) and blood transfusion (phet=0Ā·0130). Interpretation: Gastroprotectants, in particular PPIs, reduce the risk of peptic ulcer disease and its complications and promote healing of peptic ulcers in a wide range of clinical circumstances. However, this meta-analysis might have overestimated the benefits owing to small study bias

    Young childrenā€™s impressionable use of teleology: the influence of question wording and questioned topic on teleological explanations for natural phenomena

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    There is a significant body of research on children's preconceptions concerning scientific concepts and the impact this has upon their science education. One active issue concerns the extent to which young children's explanations for the existence of natural kinds rely on a teleological rationale: for example, rain is for watering the grass, or tigersā€™ stripes are for camouflage. It has been argued that this teleological tendency hampers children's ability to learn about causality in the natural world. This paper investigates two factors (question wording and topic) which it is argued have led to a misestimation of children's teleological tendencies within the area natural phenomena: i.e., those that are time-constrained, natural events or process such as snow, clouds or night. Sixty-six (5- to 8-years-old) children took part in a repeated-measures experiment, answering both open- and leading-questions across 10 topics of natural phenomena. The findings indicate that children's teleological reasoning may have been overestimated as open question forms significantly reduced their tendency to answer teleologically. Moreover, the concept of teleology is more nuanced than often suggested. Consequently, young children may be more able to learn about causal explanations for the existence of natural phenomena than the literature implies

    Sr-Nd isotope geochemistry of the early Precambrian sub-alkaline mafic igneous rocks from the southern Bastar craton, Central India

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    Srā€“Nd isotope data are reported for the early Precambrian sub-alkaline mafic igneous rocks of the southern Bastar craton, central India. These mafic rocks are mostly dykes but there are a few volcanic exposures. Field relationships together with the petrological and geochemical characteristics of these mafic dykes divide them into two groups; Meso-Neoarchaean sub-alkaline mafic dykes (BD1) and Paleoproterozoic (1.88 Ga) sub-alkaline mafic dykes (BD2). The mafic volcanics are Neoarchaean in age and have very close geochemical relationships with the BD1 type. The two groups have distinctly different concentrations of high-field strength (HFSE) and rare earth elements (REE). The BD2 dykes have higher concentrations of HFSE and REE than the BD1 dykes and associated volcanics and both groups have very distinctive petrogenetic histories. These rocks display a limited range of initial 143Nd/144Nd but a wide range of apparent initial 87Sr/86Sr. Initial 143Nd/144Nd values in the BD1 dykes and associated volcanics vary between 0.509149 and 0.509466 and in the BD2 dykes the variation is between 0.510303 and 0.510511. All samples have positive εNd values the BD1 dykes and associated volcanics have εNd values between +0.3 and +6.5 and the BD2 dykes between +1.9 to +6.0. Trace element and Nd isotope data do not suggest severe crustal contamination during the emplacement of the studied rocks. The positive εNd values suggest their derivation from a depleted mantle source. Overlapping positive εNd values suggest that a similar mantle source tapped by variable melt fractions at different times was responsible for the genesis of BD1 (and associated volcanics) and BD2 mafic dykes. The Rbā€“Sr system is susceptible to alteration and resetting during post-magmatic alteration and metamorphism. Many of the samples studied have anomalous apparent initial 87Sr/86Sr suggesting post-magmatic changes of the Rbā€“Sr system which severely restricts the use of Rbā€“Sr for petrogenetic interpretation

    Red Oak Seedlings as Indicators of Deer Browse Pressure: Gauging the Outcome of Different White-Tailed Deer Management Approaches

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    After decades of high deer populations, North American forests have lost much of their previous biodiversity. Any landscapeā€level recovery requires substantial reducā€ tions in deer herds, but modern societies and wildlife management agencies appear unable to devise appropriate solutions to this chronic ecological and human health crisis. We evaluated the effectiveness of fertility control and hunting in reducing deer impacts at Cornell University. We estimated spring deer populations and planted Quercus rubra seedlings to assess deer browse pressure, rodent attack, and other factors compromising seedling performance. Oak seedlings protected in cages grew well, but deer annually browsed ā‰„60% of unprotected seedlings. Despite female sterā€ ilization rates of \u3e90%, the deer population remained stable. Neither sterilization nor recreational hunting reduced deer browse rates and neither appears able to achieve reductions in deer populations or their impacts. We eliminated deer sterilization and recreational hunting in a core management area in favor of allowing volunteer archā€ ers to shoot deer over bait, including at night. This resulted in a substantial reduction in the deer population and a linear decline in browse rates as a function of spring deer abundance. Public trust stewardship of North American landscapes will require a fundamental overhaul in deer management to provide for a brighter future, and oak seedlings may be a promising metric to assess success. These changes will reā€ quire intense public debate and may require new approaches such as regulated comā€ mercial hunting, natural dispersal, or intentional release of important deer predators (e.g., wolves and mountain lions). Such drastic changes in deer management will be highly controversial, and at present, likely difficult to implement in North America. However, the future of our forest ecosystems and their associated biodiversity will depend on evidence to guide change in landscape management and stewardship

    Human DDX3 functions in translation and interacts with the translation initiation factor eIF3

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    The conserved RNA helicase DDX3 is of major medical importance due to its involvement in numerous cancers, human hepatitis C virus (HCV) and HIV. Although DDX3 has been reported to have a wide variety of cellular functions, its precise role remains obscure. Here, we raised a new antibody to DDX3 and used it to show that DDX3 is evenly distributed throughout the cytoplasm at steady state. Consistent with this observation, HA-tagged DDX3 also localizes to the cytoplasm. RNAi of DDX3 in both human and Drosophila cells shows that DDX3 is required for cell viability. Moreover, using RNAi, we show that DDX3 is required for expression of protein from reporter constructs. In contrast, we did not detect a role for DDX3 in nuclear steps in gene expression. Further insight into the function of DDX3 came from the observation that its major interaction partner is the multi-component translation initiation factor eIF3. We conclude that a primary function for DDX3 is in protein translation, via an interaction with eIF3
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