3,098 research outputs found

    On-Chip Detection of Beads with a New Electrical Impedance Sensor

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    Electrical impedance measurements in microfluidic chips are used for single cell analysis. Parallel electrodes are more suited than planar ones since the electrical field distribution is more homogenous. Previous studies showed methods to make parallel electrodes by incorporating an additional layer between two glass wafers, making electrical connections to both sides needed. Also alignment of electrodes is necessary, making the fabrication of parallel electrodes more elaborate. Therefore a new, simpler fabrication method is developed for the fabrication of parallel electrode chips by incorporating a floating electrode in the microchannel just by adding one step in the fabrication process. In this way, only one side of the chip contains electrical connections. Finally, electrical impedance measurements with 3 and 6 µm polystyrene beads were done. All beads were detected and we have shown that it is possible to distinguish the two beads sizes from each other with a confidence level of 95%, based on the relative change in the electrical impedance

    MSWEP : 3-hourly 0.25° global gridded precipitation (1979-2015) by merging gauge, satellite, and reanalysis data

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    Current global precipitation (P) datasets do not take full advantage of the complementary nature of satellite and reanalysis data. Here, we present Multi-Source Weighted-Ensemble Precipitation (MSWEP) version 1.1, a global P dataset for the period 1979-2015 with a 3hourly temporal and 0.25 degrees ffi spatial resolution, specifically designed for hydrological modeling. The design philosophy of MSWEP was to optimally merge the highest quality P data sources available as a function of timescale and location. The long-term mean of MSWEP was based on the CHPclim dataset but replaced with more accurate regional datasets where available. A correction for gauge under-catch and orographic effects was introduced by inferring catchment-average P from streamflow (Q) observations at 13 762 stations across the globe. The temporal variability of MSWEP was determined by weighted averaging of P anomalies from seven datasets; two based solely on interpolation of gauge observations (CPC Unified and GPCC), three on satellite remote sensing (CMORPH, GSMaP-MVK, and TMPA 3B42RT), and two on atmospheric model reanalysis (ERA-Interim and JRA-55). For each grid cell, the weight assigned to the gauge-based estimates was calculated from the gauge network density, while the weights assigned to the satellite-and reanalysis-based estimates were calculated from their comparative performance at the surrounding gauges. The quality of MSWEP was compared against four state-of-the-art gauge-adjusted P datasets (WFDEI-CRU, GPCP-1DD, TMPA 3B42, and CPC Unified) using independent P data from 125 FLUXNET tower stations around the globe. MSWEP obtained the highest daily correlation coefficient (R) among the five P datasets for 60.0% of the stations and a median R of 0.67 vs. 0.44-0.59 for the other datasets. We further evaluated the performance of MSWEP using hydrological modeling for 9011 catchments (< 50 000 km(2)) across the globe. Specifically, we calibrated the simple conceptual hydrological model HBV (Hydrologiska Byrans Vattenbalansavdelning) against daily Q observations with P from each of the different datasets. For the 1058 sparsely gauged catchments, representative of 83.9% of the global land surface (excluding Antarctica), MSWEP obtained a median calibration NSE of 0.52 vs. 0.29-0.39 for the other P datasets. MSWEP is available via http://www.gloh2o.org

    Global-scale regionalization of hydrologic model parameters

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    Current state-of-the-art models typically applied at continental to global scales (hereafter called macroscale) tend to use a priori parameters, resulting in suboptimal streamflow (Q) simulation. For the first time, a scheme for regionalization of model parameters at the global scale was developed. We used data from a diverse set of 1787 small-to-medium sized catchments ( 10-10,000 km(2)) and the simple conceptual HBV model to set up and test the scheme. Each catchment was calibrated against observed daily Q, after which 674 catchments with high calibration and validation scores, and thus presumably good-quality observed Q and forcing data, were selected to serve as donor catchments. The calibrated parameter sets for the donors were subsequently transferred to 0.5 degrees grid cells with similar climatic and physiographic characteristics, resulting in parameter maps for HBV with global coverage. For each grid cell, we used the 10 most similar donor catchments, rather than the single most similar donor, and averaged the resulting simulated Q, which enhanced model performance. The 1113 catchments not used as donors were used to independently evaluate the scheme. The regionalized parameters outperformed spatially uniform (i.e., averaged calibrated) parameters for 79% of the evaluation catchments. Substantial improvements were evident for all major Koppen-Geiger climate types and even for evaluation catchments>5000 km distant from the donors. The median improvement was about half of the performance increase achieved through calibration. HBV with regionalized parameters outperformed nine state-of-the-art macroscale models, suggesting these might also benefit from the new regionalization scheme. The produced HBV parameter maps including ancillary data are available via

    Two year cumulative incidence of trunk abnormalities in a schoolpopulation in Rotterdam, the Netherlands

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    We conducted a study of the 2 year cumulative incidence of trunk abnormalities in a cohort of 3,071 11 year old children (1,621 boys, 1,450 girls). The following data were recorded: height, weight, signs of puberty and menarche. Trunk abnormality was assessed in the erect child (asymmetry of shoulders and waistline, imbalance of the trunk, scoliosis, lordosis, kyphosis, swayback and flexibility) and by the forward bending test (FBT) (rib hump or lumbar prominence, persisting scoliosis, kyphosis and deviant lateral aspect). A normal FBT both at baseline and at follow-up was found in 84% of the boys and in 79% of the girls. The 2 year cumulative incidence of an abnormal FBT was 10% in boys and 13% in girls

    769-2 Progression and Regression of Coronary Atherosclerosis Occur within the Same Patient During Placebo Treatment and During Lipid-Lowering Therapy with Pravastatin

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    REGRESS (Regression Growth Evaluation Statin Study) is a placebo controlled multicenter study to asses the effect of 2-yr treatment with Pravastatin (PRAV) on progression and regression of angiographically documented coronary atherosclerosis (CA) in patients with a serum cholesterol between 4–8mmol/l (155-310mg/dl). Analyses of the coronary arteriograms were performed by quantitative computer analysis. The primary endpoints of the study, change in Mean Segment Diameter and Minimum Obstruction Diameter (MOD) averaged per patient, showed significant retardation of mean progression of CA in the PRAY-group as compared to the placebo (PLAC)-group. However, these mean changes per treatment group are hardly informative about individual CA-behavior. Therefore we determined for all 641 patients included in the primary MOD-analysis: 1. a mean progression score (MPS)-cumulative value of all &gt;0.4mm progressing obstructions divided by the number of contributing obstructions-, and 2. a mean regression score (MRS)-cumulative value of all&gt;0.4mm regressing obstructions divided by the number of contributing obstructions. Obstructions changing ≤0.4mm were considered stable and do not contribute to the scores. Thus, each patient is characterized by a MPS and a MRS. An overview of the patient MPS and MRS is presented in the figure below.Conclusionsignificant progression and regression of CA within the same patient occurred in 41 (13%) PRAY-patients and in 27 (9%) PLAC-patients. Thus, although pravastatin slows mean progression of CA, progression and regression of CA within the same patient still occurs in a considerable number of patients during lipid lowering therapy

    A Random Growth Model with any Real or Theoretical Degree Distribution

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    The degree distributions of complex networks are usually considered to be power law. However, it is not the case for a large number of them. We thus propose a new model able to build random growing networks with (almost) any wanted degree distribution. The degree distribution can either be theoretical or extracted from a real-world network. The main idea is to invert the recurrence equation commonly used to compute the degree distribution in order to find a convenient attachment function for node connections - commonly chosen as linear. We compute this attachment function for some classical distributions, as the power-law, broken power-law, geometric and Poisson distributions. We also use the model on an undirected version of the Twitter network, for which the degree distribution has an unusual shape. We finally show that the divergence of chosen attachment functions is heavily links to the heavy-tailed property of the obtained degree distributions.Comment: 23 pages, 3 figure

    The Doctor in Literature. Volume 4. Gender and Sex

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    This book is the fourth of four volumes in the series The Doctor in Literature. Like the first three it is intended to serve as an indexed, annotated anthology and to bring together a total of some 1500 extracts from approximately 600 works of fiction where medical doctors appear as major or minor characters. The citations in volume 4 relate to sex and gender as these issues affect physicians and medical practice, There is a lengthy chapter discussing fictional female doctors and the perceived differences between these women and their male colleagues. Nurses (generally female) and their interactions with doctors (generally male) are discussed in three chapters. Sexual encounters between patients and doctors form the subject of the last chapter
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