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Results for “adaptive sampling”

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At least 487 records · Page 27Linked to original sources
PubMed1996

In vitro measurements of inertial cavitation thresholds in human blood.

Inertial cavitation thresholds were measured in human blood exposed to pulsed ultrasound. Freshly drawn blood, bank blood and aqueous dilutions of both were used in this experimental study. Micrometer-sized polystyrene particles were used as extra potential nuclei in some samples. Focused transducers with megahertz center frequencies (2.5 MHz, 4.3 MHz) were employed to generate pulsed ultrasound to induce cavitation. Specially designed cells for hosting the blood samples were made to adapt to the experimental environment. Cavitation threshold measurements were achieved by using an active cavitation detection scheme which utilizes a highly focused transducer with a much higher center frequency (30 MHz). In 50% diluted blood samples, when no polystyrene particles were added to the samples, the threshold for cavitation was about 4.1 MPa at 2.5 MHz, while no cavitation was detected at 4.3 MHz. Generally, the measured thresholds decrease in samples with lower volume concentration of red blood cells or when polystyrene particles were added to the samples. Results show that the measured thresholds in some circumstances are in the range of output pressure of diagnostic ultrasound instrumentation; but for whole, freshly drawn blood, our apparatus was unable to detect cavitation, even at 6.3 MPa.

Blood Cells↗
PubMedDate not supplied

Dynamics of nutritional health in a community sample of american elders: a multidimensional approach using roy adaptation model.

Nutritional health of community-dwelling elders has been shown to be one of the prime indices of health, influencing the elders' ability to live independently. However, little research has been directed toward understanding the dynamics of nutritional health in community-dwelling elders using a multidimensional theory approach. The purpose of this study was to evaluate the dynamics of nutritional health within the context of Roy Adaptation Model. Factors associated with nutritional health of community-dwelling elders were cross-examined. Depressive symptoms, functional status, oral health, and income emerged as independent predictors of nutritional health adjusting for confounders. This finding lends support to the notion that multidimensional biopsychosocial factors contribute to the dynamics of nutritional health.

Activities of Daily Living↗
PubMed1997

Cytochromes P450, P420 & mixed-function oxidases as biomarkers of polychlorinated biphenyl (PCB) exposure in harbour seals (Phoca vitulina).

Hepatic microsomal cytochrome P450, EROD and ECOD activity were investigated as biomarkers of PCB exposure in harbour seals (Phoca vitulina). Due to the difficulty of obtaining undegraded seal liver samples, standard spectrophotometric methodology was adapted to investigate P420 (degraded P450) as a PCB biomarker with partially degraded samples. Total PCB burdens in both blubber and liver had positive correlations with P450, P420 and MFO activity levels. The use of P420 biomarkers in this study supports the inclusion of samples from by-caught marine mammals for future biomonitoring studies. P450 isozymes CYP1A (P4501A) and CYP2B (P4502B) in conjunction with MFO activity were investigated as "specific" biomarkers of PCB exposure. They were found to reliably reflect levels of [MC] and [PB]-type PCB exposure in harbour seal liver.

Adipose Tissue↗
PubMed1995

Reverse transcription PCR to detect enteroviruses in surface water.

We have developed a simple, fast, and efficient procedure to detect enteroviruses in water samples. Aliquots of water are subjected to two-step filtration, with the second filter containing a positively charged nylon membrane that holds back virus particles. Viruses thus adsorbed are directly lysed, and RNA is isolated by hybridization to specific oligonucleotides bound to magnetic beads. The solution used contains guanidine thiocyanate, which lyses virus particles, inactivates enzymes, e.g., RNases, allows mild hybridization conditions, and does not influence biotin-streptavidin interaction on magnetic beads. Detection and specific identification are accomplished by reverse transcription PCR of the highly conserved noncoding region at the 5' end of virus RNA combined with Southern hybridization. The system was tested with tap water artificially spiked with poliovirus vaccine and yielded a detection limit of 20 50% tissue culture infective doses per liter. We used the same procedure to investigate the water quality of surface water at public beaches by rivers and lakes. Of 40 samples tested, 7 were positive for enteroviruses. A comparison with enterobacterial contamination determined by PCR and classical microbiological methods in parallel showed that enteroviruses were found only in samples also positive for Escherichia coli. In conclusion, this procedure can easily be adapted to test large water samples and is simple enough to be used for routine determinations of water quality in terms of virus contamination.

Base Sequence↗
PubMedDate not supplied

Determination of cholinesterase activity in brain and blood samples using a plate reader.

A rapid method is described for the quantitative determination of cholinesterase activity in large batches of blood and brain samples. The technique is an adaptation of the Ellman procedure for a 96-well microtiter plate reader. Ten samples can be analyzed simultaneously in 5 min, with all calculations, including statistical analysis, done automatically. The method detection limit is 0.1 microM/mL/min for blood and 0.1 microM/g/min for brain samples. The procedure has been applied to the routine analyses of samples presented to the veterinary diagnostic laboratory. Method performance, quality control, and normal ranges of cholinesterase activity in livestock and other animals are described.

Animals↗
PubMed1975

Self-observation in general practice--the bleep method.

Recent trends in general practice towards working in multi-disciplinary teams from purpose-built premises have emphasised the need to study the ways in which doctors and other staff spend their working time.This paper describes a well-established work-study technique (activity sampling), which has been adapted to enable doctors to assess how they use their time. The method needs no observer and is cheap to operate. Five general practitioners undertook to record their surgeries for two separate weeks using the bleep method of activity sampling. The results they obtained show that the technique is both practicable in normal working conditions and is capable of providing information highly relevant to the management of general practice.

Family Practice↗
PubMed1992

Supporting women in labor: a work sampling study of the activities of labor and delivery nurses.

Studies demonstrated that support during labor and birth has a positive impact on childbirth outcomes, and that women reported they received little supportive care from nurses during parturition. This study piloted a work sampling method that was adapted to determine the proportion of time the average intrapartum nurse at a Toronto teaching hospital spends in supportive care activities. Supportive care was operationally defined within four categories of activities: emotional support, physical comfort measures, instruction/information, and advocacy. Work sampling was an effective method of measuring support as a specific aspect of direct intrapartum care. The proportion of time that nurses spent in supportive versus all other activities was 9.9 percent (95% confidence interval 7.5% and 12%), based on a sample of 616 random observations of 18 nurses. Findings are discussed in terms of the social and political factors that affect the meaning and value of the supportive activities of work by obstetric nurses.

Clinical Nursing Research↗
PubMedDate not supplied

[The soldier-senior officer relationship].

One of the main conditions for the successful adaptation to the military is the relationship between soldier and his commander. The aim of this study was to determine interpersonal relationship between soldier and his commander, evaluated by soldier on the one side and by commander on the other. The sample consisted of 144 adapted (group A) and 400 nonadapted (group NA) soldiers. The applied instruments were two questionnaires: Soldier's evaluation of a commander and Commander's perception of a soldier. Commanders most frequently noticed: emotional reactions of soldiers (anxious and depressive symptoms), then their relation to basic training and performance of soldier's duty and then their adjustment in the group (isolation, problems with sleeping and eating). It was concluded that soldiers with the problems in communication with authority before the military also had the problems with military commanders.

Adaptation, Psychological↗
PubMed2003

Vineland adaptive behavior profiles in children with autism and moderate to severe developmental delay.

The purpose of this study was to examine adaptive behaviour profiles in children with autism and moderate to severe developmental delay. Previous research has found that children with autism present a characteristic pattern of adaptive behaviour, as measured by the Vineland Adaptive Behavior Scales (VABS) (deficit in the domain of socialization, relative deficit in the domain of communication and relative strength in the domain of daily living). In this study VABS were administered (as part of a comprehensive evaluation of abilities) to a sample of 50 children with moderate to severe developmental delay (23 children with autism and 27 chronological and developmental age matched non-autistic children). Contrary to initial predictions, the sample presented fairly homogeneous adaptive behaviour profiles. Results are discussed with respect to the effectiveness of adaptive behaviour profiles in the detection of autism and the importance of employing limited chronological and developmental age ranges in the study of autism in infancy.

Adaptation, Psychological↗
PubMed2006

Adaptive MAP error concealment for dispersively packetized wavelet-coded images.

In this paper, we present an adaptive maximum a posteriori (MAP) error concealment algorithm for dispersively packetized wavelet-coded images. We model the subbands of a wavelet-coded image as Markov random fields, and use the edge characteristics in a particular subband, and regularity properties of subband/wavelet samples across scales, to adapt the potential functions locally. The resulting adaptive MAP estimation gives PSNR advantages of up to 0.7 dB compared to the competing algorithms. The advantage is most evident near the edges, which helps improve the visual quality of the reconstructed images.

Algorithms↗
PubMed2005

Combining metal oxide affinity chromatography (MOAC) and selective mass spectrometry for robust identification of in vivo protein phosphorylation sites.

BACKGROUND: Protein phosphorylation is accepted as a major regulatory pathway in plants. More than 1000 protein kinases are predicted in the Arabidopsis proteome, however, only a few studies look systematically for in vivo protein phosphorylation sites. Owing to the low stoichiometry and low abundance of phosphorylated proteins, phosphorylation site identification using mass spectrometry imposes difficulties. Moreover, the often observed poor quality of mass spectra derived from phosphopeptides results frequently in uncertain database hits. Thus, several lines of evidence have to be combined for a precise phosphorylation site identification strategy. RESULTS: Here, a strategy is presented that combines enrichment of phosphoproteins using a technique termed metaloxide affinity chromatography (MOAC) and selective ion trap mass spectrometry. The complete approach involves (i) enrichment of proteins with low phosphorylation stoichiometry out of complex mixtures using MOAC, (ii) gel separation and detection of phosphorylation using specific fluorescence staining (confirmation of enrichment), (iii) identification of phosphoprotein candidates out of the SDS-PAGE using liquid chromatography coupled to mass spectrometry, and (iv) identification of phosphorylation sites of these enriched proteins using automatic detection of H3PO4 neutral loss peaks and data-dependent MS3-fragmentation of the corresponding MS2-fragment. The utility of this approach is demonstrated by the identification of phosphorylation sites in Arabidopsis thaliana seed proteins. Regulatory importance of the identified sites is indicated by conservation of the detected sites in gene families such as ribosomal proteins and sterol dehydrogenases. To demonstrate further the wide applicability of MOAC, phosphoproteins were enriched from Chlamydomonas reinhardtii cell cultures. CONCLUSION: A novel phosphoprotein enrichment procedure MOAC was applied to seed proteins of A. thaliana and to proteins extracted from C. reinhardtii. Thus, the method can easily be adapted to suit the sample of interest since it is inexpensive and the components needed are widely available. Reproducibility of the approach was tested by monitoring phosphorylation sites on specific proteins from seeds and C. reinhardtii in duplicate experiments. The whole process is proposed as a strategy adaptable to other plant tissues providing high confidence in the identification of phosphoproteins and their corresponding phosphorylation sites.

Journal Article↗
PubMed2003

Sample size re-estimation in group-sequential response-adaptive clinical trials.

In clinical trials where the variances of the response variables are unknown, in accurate estimates of these can affect the type II error rate considerably. More accurate estimates of the variances may be obtained by taking a look at the data available part way through the trial and re-calculating the required sample size based on these new estimates. The main impetus for sample size re-estimation came from a two-stage procedure developed by Stein in 1945 and the literature is now replete with variations on this approach. In this paper, existing sample size re-estimation methods for both fixed sample and sequential clinical trial models will be reviewed. These will then be extended for use in group-sequential response-adaptive designs. In particular, a test for a recently developed group-sequential response-adaptive design, which compares two treatments with immediate normally distributed responses and unknown variances, is presented based on a modified version of Stein's test. The principal modifications involve updating the required sample size at each interim analysis and calculating the test statistic based on the current estimates of the variances. Hence, all the available information is used at each stage. Simulation is used to assess to what extent the updating of the required sample size at each interim analysis in the new test helps to attain the nominal error rates. The test is compared to modified versions of a simple test and a Stein-type group sequential t-test studied in the recent literature. These tests calculate the required sample sizes based on less accurate estimates of the variances. The type I error rate is close to the nominal value and the power is more accurately maintained in the new test.

Clinical Trials as Topic↗