829 research outputs found

    Topography driven spreading

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    Roughening a hydrophobic surface enhances its nonwetting properties into superhydrophobicity. For liquids other than water, roughness can induce a complete rollup of a droplet. However, topographic effects can also enhance partial wetting by a given liquid into complete wetting to create superwetting. In this work, a model system of spreading droplets of a nonvolatile liquid on surfaces having lithographically produced pillars is used to show that superwetting also modifies the dynamics of spreading. The edge speed-dynamic contact angle relation is shown to obey a simple power law, and such power laws are shown to apply to naturally occurring surfaces

    Frequency of blood glucose monitoring in relation to glycaemic control: observational study with diabetes database

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    Objectives: To investigate patterns of self monitoring of blood glucose concentration in diabetic patients who use insulin and to determine whether frequency of self monitoring is related to glycaemic control. Setting: Diabetes database, Tayside, Scotland. Subjects: Patients resident in Tayside in 1993­-5 who were using insulin and were registered on the database and diagnosed with insulin dependent (type 1) or non­insulin dependent (type 2) diabetes before 1993. Main outcome measures: Number of glucose monitoring reagent strips dispensed (reagent strip uptake) derived from records of prescriptions. First recorded haemoglobin A1c concentration in the study period, and reagent strips dispensed in the previous 6 months. Results: Among 807 patients with type 1 diabetes, 128 (16%) did not redeem any prescriptions for glucose monitoring reagent strips in the 3 year study period. Only 161 (20%) redeemed prescriptions for enough reagent strips to test glucose daily. The corresponding figures for the 790 patients with type 2 diabetes who used insulin were 162 (21%; no strips) and 131 (17%; daily tests). Reagent strip uptake was influenced both by age and by deprivation category. There was a direct relation between uptake and glycaemic control for 258 patients (with recorded haemoglobin A1c concentrations) with type 1 diabetes. In a linear regression model the decrease in haemoglobin A1c concentration for every extra 180 reagent strips dispensed was 0.7%. For the 290 patients with type 2 diabetes who used insulin there was no such relation. Conclusions: Self monitoring of blood glucose concentration is associated with improved glycaemic control in patients with type 1 diabetes. Regular self monitoring in patients with type 1 and type 2 diabetes is uncommon

    Holocene carbon accumulation in the peatlands of northern Scotland

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    The response of peatland carbon accumulation to climate can be complex, with internal feedbacks and processes that can dampen or amplify responses to external forcing. Records of carbon accumulation from peat cores provide a record of carbon which persists as peat over long periods of time, demonstrating the long-term response of peatland carbon stocks to climatic events. Numerous records of long-term carbon accumulation exist globally. However, peatlands from oceanic climates, and particularly blanket bog, remain under-represented. Scottish bogs, which collectively have more than 475 separate palaeoecological records, may prove to be a valuable resource for studying the impact of environmental change on past rates of carbon accumulation. Here we present 12 records of carbon accumulation from the north of Scotland. We support these results with a further 43 records where potential carbon accumulation is inferred from published ages. These reveal a trend of high carbon accumulation in the early Holocene, declining in the mid-to-late Holocene. The trend is consistent with accumulation profiles from other northern peatlands and is likely to have been caused by climatic cooling. Considerable variability in carbon accumulation rates between locations is apparent for the mid-to-late Holocene. We attribute to hydrologically induced changes in carbon accumulation which are likely to be inconsistent between sites

    On the alleged simplicity of impure proof

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    Roughly, a proof of a theorem, is “pure” if it draws only on what is “close” or “intrinsic” to that theorem. Mathematicians employ a variety of terms to identify pure proofs, saying that a pure proof is one that avoids what is “extrinsic,” “extraneous,” “distant,” “remote,” “alien,” or “foreign” to the problem or theorem under investigation. In the background of these attributions is the view that there is a distance measure (or a variety of such measures) between mathematical statements and proofs. Mathematicians have paid little attention to specifying such distance measures precisely because in practice certain methods of proof have seemed self- evidently impure by design: think for instance of analytic geometry and analytic number theory. By contrast, mathematicians have paid considerable attention to whether such impurities are a good thing or to be avoided, and some have claimed that they are valuable because generally impure proofs are simpler than pure proofs. This article is an investigation of this claim, formulated more precisely by proof- theoretic means. After assembling evidence from proof theory that may be thought to support this claim, we will argue that on the contrary this evidence does not support the claim

    Real-Time Reverse Transcription–Polymerase Chain Reaction Assay for SARS-associated Coronavirus

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    A real-time reverse transcription–polymerase chain reaction (RT-PCR) assay was developed to rapidly detect the severe acute respiratory syndrome–associated coronavirus (SARS-CoV). The assay, based on multiple primer and probe sets located in different regions of the SARS-CoV genome, could discriminate SARS-CoV from other human and animal coronaviruses with a potential detection limit of <10 genomic copies per reaction. The real-time RT-PCR assay was more sensitive than a conventional RT-PCR assay or culture isolation and proved suitable to detect SARS-CoV in clinical specimens. Application of this assay will aid in diagnosing SARS-CoV infection

    First narrow-band search for continuous gravitational waves from known pulsars in advanced detector data

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    Spinning neutron stars asymmetric with respect to their rotation axis are potential sources of continuous gravitational waves for ground-based interferometric detectors. In the case of known pulsars a fully coherent search, based on matched filtering, which uses the position and rotational parameters obtained from electromagnetic observations, can be carried out. Matched filtering maximizes the signalto- noise (SNR) ratio, but a large sensitivity loss is expected in case of even a very small mismatch between the assumed and the true signal parameters. For this reason, narrow-band analysis methods have been developed, allowing a fully coherent search for gravitational waves from known pulsars over a fraction of a hertz and several spin-down values. In this paper we describe a narrow-band search of 11 pulsars using data from Advanced LIGO’s first observing run. Although we have found several initial outliers, further studies show no significant evidence for the presence of a gravitational wave signal. Finally, we have placed upper limits on the signal strain amplitude lower than the spin-down limit for 5 of the 11 targets over the bands searched; in the case of J1813-1749 the spin-down limit has been beaten for the first time. For an additional 3 targets, the median upper limit across the search bands is below the spin-down limit. This is the most sensitive narrow-band search for continuous gravitational waves carried out so far
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