Search results for "sampling"
showing 10 items of 788 documents
Flip-angle measurement by magnetization inversion: Calibration of magnetization nutation angle in hyperpolarized 3 He magnetic resonance imaging lung…
2010
The aim of this work was to establish a new, fast, and robust method of flip-angle calibration for magnetic resonance imaging of hyperpolarized 3He. The method called flip-angle measurement with magnetization inversion is based on acquiring images from periodically inverted longitudinal magnetization created using the spatial modulation of magnetization technique. By measuring the width of the area where the magnetization was inverted by the spatial modulation of magnetization preparation in phase images, the flip angle can be generated using a simple equation. To validate and establish the limits of the proposed method, flip-angle measurement with magnetization inversion acquisitions were …
Need for Orthodontic Treatment in Pupils Aged between 12 and 15 in the Valencian Region (Spain)
2021
The World Health Organization recommends carrying out periodic epidemiological studies in order to provide a basis for the evaluation of the state of health of the population at any given time
Oral hygiene practices and dental caries prevalence among 12 and 15 years school children in Ambala, Haryana -A cross-sectional study
2015
Background: Dental caries and gum disease are a major public health problem predominantly affecting children worldwide. Therefore the present study was conducted to assess oral hygiene practices, prevalence of dental caries and periodontal diseases among 12 and 15 years old high school children in public and government schools of Ambala district, Haryana and to provide data for planning and evaluation of oral health care promotion programs. Material and Methods: A cross-sectional descriptive survey of 12 and 15 years old children in government and private schools was conducted in Ambala, Haryana. A sample of 992 school children was selected by a two-stage cluster sampling method. Dental car…
Ambulatory assessment as a means of longitudinal phenotypes characterization in psychiatric disorders
2014
Abstract Ambulatory Assessment (AA) comprises the use of in-field methods to assess individuals’ behavior, physiology, and the experience as they unfold in naturalistic settings. We propose that AA is favorable for the investigation of gene–environment interactions and for the search for endophenotypes, being able to assess the experienced environment and to track basic regulatory processes, such as stress reactivity, affective instability, and reward experience, which are potential common factors that underlie psychiatric disorders. In this article, we (a) first describe briefly the rationale of AA and summarize the key advantages of the approach, (b) highlight within-subject regulatory pr…
A Classification System for Decision-Making in the Management of Patients with Chronic Conditions
2021
Patients with chronic diseases are frequent users of healthcare services. The systematic use of stratification tools and predictive models for this group of patients can be useful for health professionals in decision-making processes. The aim of this study was to design two new classifier systems for detecting the risk of hospital admission for elderly patients with chronic conditions. In this retrospective cohort study, a set of variables related to hospital admission for patients with chronic conditions was obtained through focus groups, a health database analysis and statistical processing. To predict the probability of admission from the set of predictor variables, a logistic regression…
Is chromoendoscopy the new standard for cancer surveillance in patients with ulcerative colitis?
2008
Chromoendoscopy was introduced in 2003 as a novel 'red flag' technique that aimed to increase the sensitivity of identifying flat, neoplastic lesions in patients with ulcerative colitis. The improved sensitivity of chromoendoscopy over standard white-light endoscopy has been confirmed in European and Asian centers. This commentary discusses the findings from a prospective, controlled study from the Mount Sinai Hospital in New York. The findings of this study provide unequivocal evidence that chromoendoscopy is superior to white-light endoscopy in the detection of neoplasias in patients with IBD. The authors of this study identified a greater number of lesions and a higher number of patients…
Strategies for identifying dysplasia in Barrett's oesophagus
2012
Abstract Early neoplastic changes in Barrett's oesophagus are often only recognizable visually as discrete mucosal irregularities. With timely diagnosis, the prognosis is excellent, in contrast to advanced tumours in Barrett's oesophagus. The international specialist societies therefore recommend regular endoscopic surveillance for patients who have been diagnosed with Barrett's oesophagus. Following the 1993 Seattle Protocol, the various guidelines consistently require four-quadrant biopsy sampling every 1–2 cm over the entire Barrett's segment and additional biopsies from visually suspicious-appearing areas. This approach is time-consuming and costly, and inevitably involves sampling erro…
Seroepidemiology of pertussis infection in an urban childhood population in Cameroon.
1991
In 1989, the prevalence of IgG antibodies to pertussis toxin (PT) in a sample of 367 unvaccinated apparently healthy children 5-14 years old was estimated by ELISA in Kumba City (Cameroon). Children were recruited using a systematic random sampling from six primary schools located in different districts of the city. The sample was representative of the various socioeconomic classes. The overall prevalence was 75%; it increased from 62% in 5 year old children to 81% in children 12-14 years old (P less than 0.01). IgG antibody prevalence was positively related to the family size. Children belonging to households of nine or more members had a 2.2-fold risk (C.I. 95 per cent = 1.1-4.6) of previ…
Saliva as a testing sample for SARS-CoV-2 detection by RT-PCR in low prevalence community settings
2021
AbstractObjectivesThe number of COVID-19 cases is increasing globally and there is an urgency for a simple non-invasive method for the detection of SARS-CoV-2. Our study aimed to demonstrate that saliva can be used as a specimen for SARS-CoV-2 detection notably for the screening of extensive population groups via pooling.MethodsTo demonstrate that saliva is an appropriate specimen for SARS-CoV-2 detection a field study including 3,660 participants was performed between September 29 and October 1, 2020. We collected paired nasopharyngeal/oropharyngeal swabs (NPS) and saliva specimens and processed them within 24 hours of collection. We performed 36 serial measurements of 8 SARS-CoV-2 positiv…
Screening for colorectal cancer with immunochemical faecal occult blood tests.
2012
Population-based studies have shown that guaiac faecal occult blood testing followed by colonoscopy in case of positivity can reduce colorectal cancer mortality. However these tests have been criticised for their fairly low sensitivity. For this reason attention has been given to alternative tests. The aim of this paper is to review the evidence for screening for colorectal cancer using qualitative immunochemical faecal occult blood tests. For the complete range of tested cut-off values, immunochemical faecal occult blood tests lead to higher diagnostic yield, improved sensitivity and greater participation. The optimal number of samples and the optimal cut-off value has to suit local resour…