Search results for " Sampling"
showing 10 items of 375 documents
Higher education instructors' intention to use educational video games: an fsQCA approach
2019
Educational video games (EVGs) offer instructors a myriad of opportunities to motivate and engage students in the learning process. Nevertheless, instructors can be influenced by barriers that prevent them from using EVGs in their courses (e.g. lack of expertise with EVGs). Instructors can also be influenced by different drivers that might increase their intention to use EVGs. This research analyses the effects of four variables (perceived usefulness, perceived ease of use, attention, and relevance) as factors contributing or preventing the use of EVGs by instructors serving in Higher Education institutions. Data of 170 instructors, who were surveyed through an online questionnaire using a …
Seasonal variations of leaf area index of agricultural fields retrieved from Landsat data
2008
Abstract The derivation of leaf area index (LAI) from satellite optical data has been the subject of a large amount of work. In contrast, few papers have addressed the effective model inversion of high resolution satellite images for a complete series of data for the various crop species in a given region. The present study is focused on the assessment of a LAI model inversion approach applied to multitemporal optical data, over an agricultural region having various crop types with different crop calendars. Both the inversion approach and data sources are chosen because of their wide use. Crops in the study region (Barrax, Castilla–La Mancha, Spain) include: cereal, corn, alfalfa, sugar bee…
Coupled conditional backward sampling particle filter
2020
The conditional particle filter (CPF) is a promising algorithm for general hidden Markov model smoothing. Empirical evidence suggests that the variant of CPF with backward sampling (CBPF) performs well even with long time series. Previous theoretical results have not been able to demonstrate the improvement brought by backward sampling, whereas we provide rates showing that CBPF can remain effective with a fixed number of particles independent of the time horizon. Our result is based on analysis of a new coupling of two CBPFs, the coupled conditional backward sampling particle filter (CCBPF). We show that CCBPF has good stability properties in the sense that with fixed number of particles, …
Field rules and bias in random surveys with quota samples : an assessment of CIS surveys
2018
Surveys applying quota sampling in their final step are widely used in opinion and market research all over the world. This is also the case in Spain, where the surveys carried out by CIS (a public institution for sociological research supported by the government) have become a point of reference. The rules used by CIS to select individuals within quotas, however, could be improved as they lead to biases in age distributions. Analysing more than 545,000 responses collected in the 220 monthly barometers conducted between 1997 and 2016 by CIS, we compare the empirical distributions of the barometers with the expected distributions from the sample design and/or target populations. Among other …
A distributed real-time data prediction and adaptive sensing approach for wireless sensor networks
2018
International audience; Many approaches have been proposed in the literature to reduce energy consumption in Wireless Sensor Networks (WSNs). Influenced by the fact that radio communication and sensing are considered to be the most energy consuming activities in such networks. Most of these approaches focused on either reducing the number of collected data using adaptive sampling techniques or on reducing the number of data transmitted over the network using prediction models. In this article, we propose a novel prediction-based data reduction method. furthermore, we combine it with an adaptive sampling rate technique, allowing us to significantly decrease energy consumption and extend the …
Caries prevalence in children from Valencia (Spain) using ICDAS II criteria, 2010
2014
Objectives: To assess the oral health status of the child population and its evolution over the 2004-2010 period. Study Design: A descriptive cross-sectional study of the entire schoolchild population of the Valencia region of Spain was conducted using cluster sampling. Seventy schools were selected. The sample size was 1373 pupils, aged 6, 12 and 15 years. The children were examined in November and December 2010, at their schools, by 6 examiners calibrated in the ICDAS II method. The descriptive statistics, comparison of means and comparison of proportions (p0) was 30% in primary dentition at 6 years and 37.7% and 43.6% in permanent dentition at 12 and 15 years respectively. At 6, 12 and 1…
Twelve-Month Estrogen Levels in Premenopausal Women With Hormone Receptor–Positive Breast Cancer Receiving Adjuvant Triptorelin Plus Exemestane or Ta…
2016
Purpose To describe estradiol (E2), estrone (E1), and estrone sulfate (E1S) levels during the first year of monthly triptorelin plus exemestane or tamoxifen and to assess possible suboptimal suppression while receiving exemestane plus triptorelin. Patients and Methods Premenopausal patients with early breast cancer on the Suppression of Ovarian Function Trial who selected triptorelin as the ovarian suppression method and were randomly assigned to exemestane plus triptorelin or tamoxifen plus triptorelin were enrolled until the target population of 120 patients was reached. Blood sampling time points were 0, 3, 6, 12, 18, 24, 36, and 48 months. Serum estrogens were measured with a highly sen…
A new principle to normalize plasma concentrations allowing single-sample clearance determinations in both children and adults.
1992
A sufficiently accurate quantification of renal function requiring only one plasma sample without an additional gamma-camera study has, until now, only been possible in adults. A new principle will be presented here allowing the universal application of known algorithms, regardless of the clearance substance used, by normalizing the plasma concentrations with respect to the individual body dimensions of the patients - for infants as well as for adults. In this respect, algorithms are developed for clearance determinations using technetium-99m mercaptoacetyltriglycine (99mTc-MAG3), which are based on steady-state studies as the reference. They allow the calculation of quantitative clearance …
Forty-two supernumerary marker chromosomes (SMCs) in 43,273 prenatal samples: chromosomal distribution, clinical findings, and UPD studies.
2005
Fluorescence in situ hybridization (FISH) analyses were performed on supernumerary marker chromosomes (SMCs) detected in 43 273 prenatal diagnoses over a period of 11 years, 1993–2003. A total of 42 pregnancies with SMC were identified, indicating a prevalence of one in 1032. A total of 15 SMCs were endowed with detectable euchromatin (prevalence, 1/2884), including six SMCs containing the cat eye critical region (CECR) on chromosome 22q11.21 (1/7212). De novo SMCs were found in 29 pregnancies (1/1492), including 14 euchromatic SMCs (48.2%). Follow-up studies were available for 24 cases. Nine pregnancies (37.5%) were terminated; two children (8.3%) were born with Pallister–Killian syndrome …
Stability of habitual physical activity and sport participation: a longitudinal tracking study
2007
Although one of the most important aims of physical education and public sport policy is to encourage life-long habitual physical activity, very little is known of the stability or tracking of physical activity. As a part of a larger research project called Cardiovascular Risks in Young Finns, the purpose of the study reported here was to investigate the stability (tracking) of leisure-time physical activity and sport participation at intervals of 3, 6, 9 and 12 years from age 9 to 30. The subjects, chosen by stratified random sample, represent five geographical areas of the country and eight gender-age cohorts (9, 12, 15 and 18 years old in 1980). Physical activity and sport participation …