Search results for "sampling"
showing 10 items of 788 documents
Portability in analytical chemistry: a green and democratic way for sustainability
2019
International audience; Recent advances in portability of analytical equipment have been considered to enlighten the advantages offered by portable instrumentation on greening the analytical methods. Their use drastically reduces sampling, sample stockage, and transport, thus avoiding environmental side effects and risks, also improving decision-making. The fact that portable instrumentation is, in general, less expensive than bench instruments and apparatuses makes also available the analytical tools for extended sectors of the population, thus making accessible the advantages derived from analytical methods. The role of sensor technology and portable miniaturized systems has been consider…
Cooperative compressive power spectrum estimation in wireless fading channels
2017
This paper considers multiple wireless sensors that cooperatively estimate the power spectrum of the signals received from several sources. We extend our previous work on cooperative compressive power spectrum estimation to accommodate the scenario where the statistics of the fading channels experienced by different sensors are different. The signals received from the sources are assumed to be time-domain wide-sense stationary processes. Multiple sensors are organized into several groups, where each group estimates a different subset of lags of the temporal correlation. A fusion centre (FC) combines these estimates to obtain the power spectrum. As each sensor group computes correlation esti…
Derivation of high-resolution leaf area index maps in support of validation activities: Application to the cropland Barrax site
2009
The validation of coarse satellite-derived products from field measurements generally relies on up-scaling the field data to the corresponding satellite products. This question is commonly addressed through the generation of a reference high-resolution map of an area covering several moderate resolution pixels. This paper describes a method by which reference leaf area index (LAI) maps can be generated from ground-truth LAI measurements. The method is based on a multivariate ordinary least squares (OLS) algorithm which uses an iteratively re-weighted least squares (IRLS) algorithm. It provides an empirical relationship (i.e. a transfer function) between in situ measurements and concomitant …
Measuring the Spatial Homogeneity in Corneal Endotheliums by Means of a Randomization Test
1999
Quantification of regularity of cell sizes and the spatial arrangement of cells in corneal endotheliums becomes of a great importance associated to stress situations such as cataract surgery, corneal transplantation or implantation of intra-ocular lenses. A new index of regularity of the spatial distribution of cell sizes in corneal endotheliums is proposed. The corneal endothelium is described by means of a spatial marked point pattern (the cell centroids marked with the cell areas). The hypothesis of no dependency between mark and locations is tested by a Monte Carlo test. The new index is the p-value of the test validating the hypothesis. Pairs of endotheliums from different eyes of the …
Fractal dimension confidence interval estimation of epicentral distributions
1999
Estimates of the fractal dimension of hypocentral distributions require evaluating the range of independent variables in which fractal parameters exhibit a power law. Systematic and accidental errors are produced mainly by the subjective selection of this range, the insufficiency of data sets as well as by hypocenter mislocations. Therefore it is very important to determine the confidence intervals which are associated with fractal dimension estimates. The effects of various sources of errors are studied using different geometric clusters of epicenters, which have been synthetically generated using a multicluster algorithm with different hierarchical levels, so as to reproduce some characte…
On-line high-pressure extraction-high-performance liquid chromatography
1983
Abstract A coupling unit is described that allows on-line operation of a high-pressure extraction apparatus with a high-performance liquid chromatograph. The unit consists of two high-pressure sample-injection valves, connected in series. The first valve operates as a switching valve to the loop and controls the release of pressure along a packed microbore column. Two short, packed microbore columns are positioned between the first and second valve, sampling the extracted compounds over a desired period and simultaneously operating as sample loop for the second valve; the latter is the injector for the high-performance liquid chromatographic column. The unit was tested by continuous extract…
Force probe simulations using a hybrid scheme with virtual sites.
2017
Hybrid simulations, in which a part of the system is treated with atomistic resolution and the remainder is represented on a coarse-grained level, allow for fast sampling while using the accuracy of atomistic force fields. We apply a hybrid scheme to study the mechanical unfolding and refolding of a molecular complex using force probe molecular dynamics (FPMD) simulations. The degrees of freedom of the solvent molecules are treated in a coarse-grained manner while atomistic resolution is retained for the solute. The coupling between the solvent and the solute is provided using virtual sites. We test two different common coarse-graining procedures, the iterative Boltzmann inversion method an…
Circulating cell-free DNA: an up-coming molecular marker in exercise physiology.
2012
The phenomenon of circulating cell-free DNA (cfDNA) concentrations is of importance for many biomedical disciplines including the field of exercise physiology. Increases of cfDNA due to exercise are described to be a potential hallmark for the overtraining syndrome and might be related to, or trigger adaptations of, immune function induced by strenuous exercise. At the same time, exercise provides a practicable model for studying the phenomenon of cfDNA that is described to be of pathophysiological relevance for different topics in clinical medicine like autoimmune diseases and cancer. In this review, we are summarizing the current knowledge of exercise-based acute and chronic alterations i…
Consumers' perceptions of mobile banking continuous usage in Finland and South Africa
2015
This study examines continuous usage behaviour related to mobile banking (m-banking) among consumers living in Finland (FI) and South Africa (ZA). The study investigates three post-adoption behavioural consequences - namely, trust, satisfaction and word of mouth. Using purposeful sampling techniques, we found that trust plays a significant role in promoting continuous usage of m-banking. In general, the respondents reported high levels of trust in m-banking technology and were satisfied with the m-banking application and services. In addition, convenience, user friendliness and speed emerged as the main sub-topics related to satisfaction. In most cases, the convenience of using m-banking do…
Investigating a simplified method for noninvasive genetic sampling in East African mammals using silica dried scat swabs
2020
Abstract Swabbing scat has proved to be an effective noninvasive method to collect DNA from mammals in the field. Previously, this method has relied on preservative liquids or freezing to preserve the DNA collected on swabs. In this study, we determine the effectiveness of using silica to simply dry the swab in field as an alternative way to prevent DNA degredation. Four species were included in the study; reticulated giraffe, impala, fringe‐eared oryx, and lion. Swabs were taken at multiple time points for giraffe and impala scat samples, with the lion and oryx sampled opportunistically. Mitochondrial DNA was successfully amplified and sequenced from scat swabs from all species; however, e…