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Data Sampling (data + sampling)

Distribution by Scientific Domains

Medical Sciences	40%

Selected Abstracts

Suspended sediment load estimation and the problem of inadequate data sampling: a fractal view

EARTH SURFACE PROCESSES AND LANDFORMS, Issue 4 2006
Bellie Sivakumar
Abstract Suspended sediment load estimation at high resolutions is an extremely difficult task, because: (1) it depends on the availability of high-resolution water discharge and suspended sediment concentration measurements, which are often not available; (2) any errors in the measurements of these two components could significantly influence the accuracy of suspended sediment load estimation; and (3) direct measurements are very expensive. The purpose of this study is to approach this sampling problem from a new perspective of fractals (or scaling), which could provide important information on the transformation of suspended sediment load data from one scale to another. This is done by investigating the possible presence of fractal behaviour in the daily suspended sediment load data for the Mississippi River basin (at St. Louis, Missouri). The presence of fractal behaviour is investigated using five different methods, ranging from general to specific and from mono-fractal to multi-fractal: (1) autocorrelation function; (2) power spectrum; (3) probability distribution function; (4) box dimension; and (5) statistical moment scaling function. The results indicate the presence of multi-fractal behaviour in the suspended sediment load data, suggesting the possibility of transformation of data from one scale to another using a multi-dimensional model. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Dental hygienists' views on communicative factors and interpersonal processes in prevention and treatment of periodontal disease

INTERNATIONAL JOURNAL OF DENTAL HYGIENE, Issue 3 2010
J Stenman
To cite this article: Int J Dent Hygiene,8, 2010; 213,218 DOI: 10.1111/j.1601-5037.2010.00459.x Stenman J, Wennström JL, Abrahamsson KH. Dental hygienists' views on communicative factors and interpersonal processes in prevention and treatment of periodontal disease. Abstract:, Objective:, The aim of this study was to explore views of DHs on communicative issues and interpersonal processes of importance in the prevention and treatment of periodontal disease. Method:, The qualitative method of Grounded Theory (GT) was chosen for data sampling and analysis. Audio-taped and open-ended interviews were conducted with 17 dental hygienists. The interviews were transcribed verbatim and analysed in a hierarchical coding process, according to the principles of GT. Result:, In the analysis a core category was identified as ,to be successful in information and oral health education and managing desirable behavioural changes'. The core concept was related to four additional categories and dimensions; (i) ,to establish a trustful relationship with the patient', (ii) ,to present information about the oral health status and to give oral hygiene instructions', (iii) ,to be professional in the role as a dental hygienist' and (iv) ,to have a supportive working environment in order to feel satisfaction with the work and to reach desirable treatment results'. Conclusion:, The results describe a psychosocial process that elucidates the importance of building a trustful relationship with the patient, feeling secure in one's professional role as a DH and last but not least, the importance of having support from colleagues and the clinical manager to be successful in the prevention and treatment of periodontal diseases. [source]

Study Design for Assessing Species Environment Relationships and Developing Indicator Systems for Ecological Changesin Floodplains , The Approach of the RIVA Project

INTERNATIONAL REVIEW OF HYDROBIOLOGY, Issue 4 2006
Klaus Henle
Abstract In this article the study design and data sampling of the RIVA project , "Development and Testing of a Robust Indicator System for Ecological Changes in Floodplain Systems" , are described. The project was set up to improve existing approaches to study species environment relationships as a basis for the development of indicator systems and predictive models. Periodically flooded grassland was used as a model system. It is agriculturally used at a level of intermediate intensity and is the major habitat type along the Middle Elbe, Germany. We chose a main study area to analyse species environment relationships and two reference sites for testing the transferability of the results. Using a stratified random sampling scheme, we distributed 36 study plots across the main study site and 12 plots each within the reference sites. In each of the study plots, hydrological and soil variables were measured and plants, molluscs, and carabid beetles were sampled. Hoverflies were collected on a subset of the sampling plots. A brief summary of first results is then provided. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Measuring the Information Content of the Beige Book: A Mixed Data Sampling Approach

JOURNAL OF MONEY, CREDIT AND BANKING, Issue 1 2009
MICHELLE T. ARMESTO
data sampling frequency; textual analysis; DICTION; Beige Book Studies of the predictive ability of the Federal Reserve's Beige Book for aggregate output and employment have proven inconclusive. This might be attributed, in part, to its irregular release schedule. We use a model that allows for data sampling at mixed frequencies to analyze the predictive power of the Beige Book. We find that the Beige Book's national summary and District reports predict GDP and aggregate employment and that most District reports provide information content for regional employment. In addition, there appears to be an asymmetry in the predictive content of the Beige Book language. [source]

High temporal and spatial resolution 4D MRA using spiral data sampling and sliding window reconstruction

MAGNETIC RESONANCE IN MEDICINE, Issue 1 2004
He Zhu
Abstract Contrast-enhanced magnetic resonance angiography (CE-MRA) requires high spatial resolution to demonstrate detailed vasculature and high temporal resolution to capture the contrast bolus. Sparse bright voxels in MRA permit substantial undersampling in MRI data acquisition, allowing simultaneous high temporal and spatial resolution. We developed a time-resolved 3D MRA technique using the efficient spiral sampling trajectory, and performed off-resonance corrections using inhomogeneity field maps. View sharing and sliding window reconstruction were utilized to generate high temporal resolution. High-resolution 3D angiograms were generated at 1,2 s per frame, with a 5,8 ml gadolinium dose, in patients with vascular disease. Magn Reson Med 52:14,18, 2004. © 2004 Wiley-Liss, Inc. [source]