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Results for “Area Analysis”

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At least 181 records · Page 10Linked to original sources
PubMed2002

Quantification of [(123)I]PE2I binding to dopamine transporters with SPET.

The iodinated cocaine derivative [(123)I]PE2I is a new selective ligand for in vivo studies of the dopamine transporter (DAT) with single-photon emission tomography (SPET). The aim of the present study was to describe a method for accurate quantification of binding data following a bolus injection of [(123)I]PE2I. Six healthy subjects (age 51+/-24 years) underwent xenon-133 SPET for quantification of regional CBF and [(123)I]PE2I SPET for quantification of DAT binding. rCBFs were within normal limits in all subjects. Fitting data to a two-tissue compartment model resulted in striatal K(1) values of 0.39+/-0.08 ml ml(-1) min(-1), equal to a first-pass extraction fraction of 0.72+/-0.13. Distribution volumes (DVs) were calculated using compartment analysis, area under the curve analysis and Logan analysis. Logan analysis is preferred since stable DV values were already obtained 120 min after [(123)I]PE2I injection. Mean striatal DV was 37.9+/-9.6 ml ml(-1) and mean occipital cortex DV was 5.5+/-0.7 ml ml(-1). In the absence of local pathology in a reference tissue, Logan analysis without blood sampling is an attractive method for accurate quantification of striatal [(123)I]PE2I binding. The distribution volume ratio (DVR) (6.6+/-1.4) was in good agreement with the DVR calculated with blood (6.7+/-1.4).

Area Under Curve↗
PubMed2005

The assessment of risk caused by domino effect in quantitative area risk analysis.

A systematic procedure for the quantitative assessment of the risk caused by domino effect was developed. Escalation vectors, defined as the physical effects responsible of possible accident propagation, were identified for the primary scenarios usually considered in the QRA procedure. Starting from the assessment of the escalation vectors, the methodology allows the identification of credible domino scenarios and the estimation of their expected severity. A simplified technique was introduced for consequence and vulnerability assessment of domino scenarios. The overall contribution of domino effect to individual risk, societal risk and to the potential life loss index was calculated by a specific procedure, taking into account all the credible combinations of secondary events that may be triggered by each primary scenario. The development of a software package allowed the application of the procedure to several case-studies. The results evidenced the relevant modifications of the risk indexes caused by domino effect and the importance of including the quantitative analysis of domino effect in QRA, in order to correctly assess and control the risk caused by escalation scenarios.

Accidents↗
PubMed2005

Aqueous ferrofluid of magnetite nanoparticles: Fluorescence labeling and magnetophoretic control.

A method is presented for the preparation of a biocompatible ferrofluid containing dye-functionalized magnetite nanoparticles that can serve as fluorescent markers. This method entails the surface functionalization of magnetite nanoparticles using citric acid to produce a stable aqueous dispersion and the subsequent binding of fluorescent dyes to the surface of the particles. Several ferrofluid samples were prepared and characterized using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), BET surface area analysis, transmission electron microscopy (TEM), and SQUID magnetometry. In addition, confocal fluorescence microscopy was used to study the response of the fluorescent nanoparticles to an applied magnetic field and their uptake by cells in vitro. Results are presented on the distribution of particle sizes, the fluorescent and magnetic properties of the nanoparticles, and the nature of their surface bonds. Biocompatible ferrofluids with fluorescent nanoparticles enable optical tracking of basic processes at the cellular level combined with magnetophoretic manipulation and should be of substantial value to researchers engaged in both fundamental and applied biomedical research.

Journal Article↗
PubMed2003

Large-area topography analysis and near-field Raman spectroscopy using bent fibre probes.

We present a method for combined far-field Raman imaging, topography analysis and near-field spectroscopy. Surface-enhanced Raman spectra of Rhodamine 6G (R6G) deposited on silver nanoparticles were recorded using a bent fibre aperture-type near-field scanning optical microscope (NSOM) operated in illumination mode. Special measures were taken to enable optical normal-force detection for control of the tip-sample distance. Comparisons between far-field Raman images of R6G-covered Ag particle aggregates with topographic images recorded using atomic force microscopy (AFM) indicate saturation effects due to resonance excitation.

Journal Article↗
PubMed1989

Modelling migration flows between areas: an analysis for London using the census and OPCS Longitudinal Study.

"This paper analyses migration between the London boroughs using a discrete probability model, but with a correction for excess dispersion to that expected under the Poisson process. Two sources of migration data are used: one-year migration from the 1981 Census; and ten-year migration from the OPCS Longitudinal Study. The evidence from both sets is that both housing and labour market factors are relevant to explaining interborough migration, in addition to the distance and mass terms of the basic gravity model. The labour market effects suggest that migration generally equilibrates differences in excess labour supply between the boroughs, though less strongly in the recession year 1980-81." (SUMMARY IN FRE AND GER)

Demography↗
PubMed1993

Patterns of Pap smear use in the Rimini area: an analysis of women's attitudes to the test.

The use of the Pap test is a method of the prevention of cervical cancer in our local division of the Sanitary Unit and has been studied with the help of a questionnaire which was completed by women who had adopted this test. The socioeconomic characteristics, level of education, occupation and general attitudes regarding the Pap test as well as how the women had acquired knowledge of the test, have all been examined. From an analysis of the answers, we have been able to trace a precise social, economic and cultural profile of the type of women who take advantage of this test. Principally, we are dealing with women aged 40-49 years, often with children, with a medium to low level of education, who are mainly housewives and white-collar workers. Very few elderly women present themselves for the Pap test. We have noticed that there is a direct decrease in the use of preventive methods, proportional to the increase in age. These results demonstrate that an erratic use of this preventive method, in the absence of an organized screening programme, seems only to involve women who are among those at less risk from cervical cancer.

Adult↗
PubMed2000

History or current selection? A molecular analysis of 'area effects' in the land snail Cepaea nemoralis.

We have used molecular variation in microsatellite and mitochondrial DNA to throw light on the origins of enigmatic geographical patterns, known as 'area effects', in the shell polymorphisms of the land snail Cepaea nemoralis. Our aim was to assess the relative importance of recent selection and historical events in the formation of these patterns. On the Marlborough Downs in Wiltshire, England, the 'type locality' for area effects, the frequencies of microsatellites are significantly associated with the frequencies of alleles for shell banding. A less clear association is found between microsatellites and shell colour. Mitochondrial haplotypes show no significant relationships. Although the correlated geographical patterns could be the results of random genetic drift from an initially uniform array of populations, the magnitudes of the patterns, and of the correlations between them, seem too strong to have arisen by drift since the last glaciation. Our results suggest that invasions from refugia have been the most important factors in forming area effects.

Animals↗
PubMed1986

Mammary carcinoma: DNA analysis in areas showing different histological features in the same tumor.

Specimens from 17 invasive primary breast adenocarcinomas that showed distinct areas of different histologic appearance were examined with respects to nuclear DNA content of the tumor cells. DNA in individual tumor cells was measured in sections from the original paraffin-embedded specimens. DNA distribution patterns obtained from the histologically different areas in the same tumor were compared. In 15 cases these patterns were very similar, whereas in two cases the patterns were found to be different. The results suggest that, in spite of histological variations, breast carcinoma often show similar nuclear DNA content throughout the entire tumor. Since nuclear DNA content in breast tumors has been shown to be correlated to prognosis, our observations suggest that the differences in structural pattern occasionally seen in mammary adenocarcinoma do not necessarily reflect a dedifferentiation towards more malignant tumor populations.

Adenocarcinoma↗
PubMed1998

Mutational analysis of AREA, a transcriptional activator mediating nitrogen metabolite repression in Aspergillus nidulans and a member of the "streetwise" GATA family of transcription factors.

The transcriptional activator AREA is a member of the GATA family of transcription factors and mediates nitrogen metabolite repression in the fungus Aspergillus nidulans. The nutritional versatility of A. nidulans and its amenability to classical and reverse genetic manipulations make the AREA DNA binding domain (DBD) a useful model for analyzing GATA family DBDs, particularly as structures of two AREA-DNA complexes have been determined. The 109 extant mutant forms of the AREA DBD surveyed here constitute one of the highest totals of eukaryotic transcription factor DBD mutants, are discussed in light of the roles of individual residues, and are compared to corresponding mutant sequence changes in other fungal GATA factor DBDs. Other topics include delineation of the DBD using both homology and mutational truncation, use of frameshift reversion to detect regions of tolerance to mutational change, the finding that duplication of the DBD can apparently enhance AREA function, and use of the AREA system to analyze a vertebrate GATA factor DBD. Some major points to emerge from work on the AREA DBD are (i) tolerance to sequence change (with retention of function) is surprisingly great, (ii) mutational changes in a transcription factor can have widely differing, even opposing, effects on expression of different structural genes so that monitoring expression of one or even several structural genes can be insufficient and possibly misleading, and (iii) a mutational change altering local hydrophobic packing and DNA binding target specificity can markedly influence the behavior of mutational changes elsewhere in the DBD.

Amino Acid Sequence↗
PubMed1985

New approach to area image analysis of Scheimpflug photos of the anterior eye segment.

Based on the Scheimpflug principle, the rotating photo slitlamp Topcon SL 45 can produce photos of a high depth of focus from a slit beam through the anterior eye segment. The Scheimpflug photos are digitized with a special semiconductor camera. A new method, using the digital picture subtraction, is presented. This method is suited for experimental and clinical studies dealing with the development of the lens opacities.

Anterior Eye Segment↗