SEARCH · PubMed Health

Results for “Capture”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 811 records · Page 45Linked to original sources

PubMed2000

Capture-recapture method to determine the best design of a surveillance system. Application to a thyroid cancer registry.

The capture-recapture method is often confronted, when assessing completeness of surveys, to problems of dependence of data sources. The objective of this paper is to discuss the application of capture-recapture methods to choose the optimal combination of sources for a surveillance system. Our approach is based on: (1) using multiple sources, (2) assessing dependence between sources and between pools of dependent sources and other sources, (3) ruling out combinations that yield biased estimates, and (4) choosing the combinations of sources that have the best ratio between precision and applicability. We studied the independence for each pair of sources by computing the capture-recapture odds ratio. We characterized all combinations of sources by their sensitivity, coefficient of variation of the estimated number of cases, and level of resources needed to ascertain cases. Application of the approach is illustrated by data from a survey of thyroid cancer in New Caledonia, where five sources were used to estimate the incidence. The five sources provided 119 cases; the exhaustivity of sources and combinations of sources varied from 27.1 to 99.2%. Determination of dependence revealed ten dependencies out of 22 combinations. Coefficients of variation of the estimated number of cases varied from 0.83 to 27.79. The preferred combination included four sources and had a sensitivity of 97.5 and a coefficient of variation of 0.94. An assessment of dependence, based on simple criteria, can be used to choose the best combination of sources for a registry or a surveillance system.

Epidemiologic Methods↗

PubMed2001

Capture rates of the European pine sawfly, Neodiprion sertifer, in pheromone traps, with special regard to effects of wind speed.

Males of the European pine sawfly, Neodiprion sertifer Geoffr., were marked and released downwind from pheromone traps, baited with 100 micrograms of the sex pheromone (2S,3S,7S)-3,7-dimethyl-2-pentadecyl acetate. Males were released 5 m downwind from one trap, or downwind from five traps, 50 m or 200 m away. The average capture rates after 24 hr were 21.5%, 17.7% and 3.8%, respectively. The capture rate was highest at moderate wind speeds (1-2 m/sec) in the 50 m experiments, whereas it decreased above wind speeds of 1.5 m/sec in the 200 m experiments. With no precipitation and > 13.5 degrees C during overcast, wind speed is presumably the most important climatic factor for N. sertifer males flying upwind to a pheromone source. Travel time, the elapsed time form take-off to landing on the trap, varied considerably, and the shortest recorded travel times were 1, 6 and 45 min for the 5, 50, and 200 m experiments, respectively. The trap efficiency i.e., number of captured males per number of males that landed on the trap, was estimated at 52% in the 5 m experiments. The sampling range after 24 hr was calculated at approximately 400 m by regression analysis. The combination of the males' flight ability during upwind progress and their longevity (12 days), suggests a potentially large seasonal sampling range of the traps used in this study.

Animals↗

PubMed1999

Spleen capture of nanoparticles: influence of animal species and surface characteristics.

PURPOSE: To investigate the influence of animal species and nanoparticle surface characteristics on the intrasplenic distribution of polystyrene nanoparticles. METHODS: Two types of fluorescent polystyrene nanoparticles (Estapor and Fluoresbrite), plain or coated, were used in mice and rats. First, a fluorimetric method was developed for nanoparticle tissue quantification. Then, intrasplenic distribution of plain or coated nanoparticles was studied using histological examination and image analysis. Finally, the role of direct interactions between nanoparticles and spleen capturing cells was assessed by in vitro binding assays, using incubation of thick spleen slices with polystyrene nanoparticles. RESULTS: The two types of polystyrene nanoparticles showed different levels of trapping: Fluoresbrite nanoparticles were more efficiently trapped by the spleen than Estapor nanoparticles, both in mice and rats. In mice, most of the injected nanoparticles were localized in the marginal zone of the spleen, involving a special population of capturing cells, while in rats, the predominant capture occured in the red pulp. In mice, coated nanoparticles were localized both in the marginal zone and in the red pulp, whereas the coating did not seem to change the intrasplenic distribution of the nanoparticles in rats. CONCLUSIONS: These complementary approaches showed different uptake pathways of nanoparticles, according to their surface characteristics and the rodent species used.

Animals↗

PubMed1996

Visual quality and attentional capture: a challenge to the special role of abrupt onsets.

This article investigates the nature of stimulus-driven attentional capture. Previous studies (e.g., J. Jonides & S. Yantis, 1988) have suggested that only a single visual feature--abrupt visual onset--can elicit stimulus-driven attentional capture. Two experiments are reported that challenge the special status of abrupt onsets in attentional capture. In particular, this evidence suggests that abrupt onsets appear to attenuate display-size effects only in certain experimental contexts that inadvertently increase the ease with which they are perceived. Consequently, the special status attributed to abrupt onsets is argued to derive from their higher visual quality.

Attention↗

PubMed1998

Selectivity in distraction by irrelevant featural singletons: evidence for two forms of attentional capture.

Four experiments addressed the degree of top-down control over attentional capture in visual search for featural singletons. In a modified spatial cuing paradigm, the spatial relationship and featural similarity of target and distractor singletons were systematically varied. Contrary to previous studies, all 4 experiments showed that when searching for a singleton target, an irrelevant featural singleton captures spatial attention only when defined by the same feature value as the target. Experiments 2, 3 and 4 provided a potential explanation for the discrepancy with previous studies by showing that irrelevant singletons can produce distraction effects that are dissociable from shifts of spatial attention. The results suggest the existence of 2 distinct forms of attentional capture.

Adolescent↗

PubMed1999

Do equiluminant object onsets capture visual attention?

S. Yantis and A. P. Hillstrom (1994) have claimed that abrupt onset of a new visual object captures attention even when the new object is equiluminant with its background, implying that attention is captured at the level of object descriptions rather than at the level of luminance change detection. S. Yantis and A. P. Hillstrom's experiments contained potential flaws that call their conclusion into question. The present article reports 5 experiments investigating these and related issues. The results suggest that for abruptly onsetting visual objects to capture attention, detection of change in a dimension of sensory stimulation is a necessary, but perhaps not a sufficient, requirement. Evidence is also presented against the view that attentional priority for new objects arises as a result of visual masking of old objects in the same displays.

Adult↗

PubMed2001

Attentional capture by irrelevant color singletons.

Four experiments investigated attentional capture by a color singleton in visual search for a nonsingleton target. B. S. Gibson and E. M. Kelsey (1998) found that a color singleton in a precuing array facilitated target discrimination at that location if the same color also signaled the target array onset. The authors found similar cuing effects regardless of whether the singleton color matched the target array and regardless of whether subjects could anticipate the singleton or target-array color. In Experiment 4, a color singleton captured attention when it appeared in the precuing array but not when it appeared in the target array. The results indicate that attentional control settings for displaywide attributes are imprecise: Although subjects may anticipate a specific color, they cannot avoid attentional capture by other irrelevant colors. In addition, the effect of irrelevant singletons depends on whether a target is simultaneously present in the array.

Attention↗

PubMed2002

Capturing the suffix: cognitive streaming in immediate serial recall.

Adding an irrelevant item to the end of an auditory to-be-remembered list increases error on the last list items appreciably, known as the suffix effect. The phenomenon of auditory capture (e.g., Bregman & Rudnicky, 1975), namely, the tendency for a sequence of similar items to form a stream that at the same time isolates perceptually dissimilar members of the sequence, is exploited to explore the suffix effect. Irrelevant items interleaved between to-be-remembered items are used to capture the suffix with the aim of reducing its impact. Four experiments illustrate how the properties of the irrelevant sequence promote capture. The results are problematic for models of the suffix that involve masking of the last list item; instead, models based on grouping are favored.

Attention↗

PubMed2005

Auditory attentional capture during serial recall: violations at encoding of an algorithm-based neural model?

A novel attentional capture effect is reported in which visual-verbal serial recall was disrupted if a single deviation in the interstimulus interval occurred within otherwise regularly presented task-irrelevant spoken items. The degree of disruption was the same whether the temporal deviant was embedded in a sequence made up of a repeating item or a sequence of changing items. Moreover, the effect was evident during the presentation of the to-be-remembered sequence but not during rehearsal just prior to recall, suggesting that the encoding of sequences is particularly susceptible. The results suggest that attentional capture is due to a violation of an algorithm rather than an aggregate-based neural model and further undermine an attentional capture-based account of the classical changing-state irrelevant sound effect.

Algorithms↗

PubMed2005

Chaotic capture of Jupiter's Trojan asteroids in the early Solar System.

Jupiter's Trojans are asteroids that follow essentially the same orbit as Jupiter, but lead or trail the planet by an angular distance of approximately 60 degrees (co-orbital motion). They are hypothesized to be planetesimals that formed near Jupiter and were captured onto their current orbits while Jupiter was growing, possibly with the help of gas drag and/or collisions. This idea, however, cannot explain some basic properties of the Trojan population, in particular its broad orbital inclination distribution, which ranges up to approximately 40 degrees (ref. 8). Here we show that the Trojans could have formed in more distant regions and been subsequently captured into co-orbital motion with Jupiter during the time when the giant planets migrated by removing neighbouring planetesimals. The capture was possible during a short period of time, just after Jupiter and Saturn crossed their mutual 1:2 resonance, when the dynamics of the Trojan region were completely chaotic. Our simulations of this process satisfactorily reproduce the orbital distribution of the Trojans and their total mass.

Journal Article↗

PubMed2006

Neptune's capture of its moon Triton in a binary-planet gravitational encounter.

Triton is Neptune's principal satellite and is by far the largest retrograde satellite in the Solar System (its mass is approximately 40 per cent greater than that of Pluto). Its inclined and circular orbit lies between a group of small inner prograde satellites and a number of exterior irregular satellites with both prograde and retrograde orbits. This unusual configuration has led to the belief that Triton originally orbited the Sun before being captured in orbit around Neptune. Existing models for its capture, however, all have significant bottlenecks that make their effectiveness doubtful. Here we report that a three-body gravitational encounter between a binary system (of approximately 10(3)-kilometre-sized bodies) and Neptune is a far more likely explanation for Triton's capture. Our model predicts that Triton was once a member of a binary with a range of plausible characteristics, including ones similar to the Pluto-Charon pair.

Journal Article↗

PubMed2004

Ordered DNA release and target capture in RAG transposition.

Following V(D)J cleavage, the newly liberated DNA signal ends can be either fused together into a signal joint or used as donor DNA in RAG-mediated transposition. We find that both V(D)J cleavage and release of flanking coding DNA occur before the target capture step of transposition can proceed; no coding DNA is ever detected in the target capture complex. Separately from its role in V(D)J cleavage, the DDE motif of the RAG1/2 active site is specifically required for target DNA capture. The requirement for cleavage and release of coding DNA prior to either physical target binding or functional target commitment suggests that the RAG1/2 transposase contains a single binding site for non-RSS DNA that can accommodate either target DNA or coding DNA, but not both together. Perhaps the presence of coding DNA may aid in preventing transpositional resolution of V(D)J recombination intermediates.

Binding Sites↗

PubMed2000

Direct on-filter assay of subtilisin-type proteolytic enzymes for rapid analysis of analyte captured from the workplace atmosphere.

A simple assay for some proteolytic enzymes has been developed which can be performed directly on the surface of a cellulose nitrate filter used to capture the analyte during workplace monitoring for health and safety purposes. Following air sampling the analysis is performed on the filter which is retained within the air sampler. This involves two steps: first, a 15 min incubation in which the captured enzyme is dissolved and then digests an alkaline-phosphatase-labelled antibody immobilised as a small dot on the surface of the filter; and second, is a 10 min incubation with substrate solution, which follows an in situ wash under a vacuum. During the incubation colour develops on the spot at the location of the immobilised enzyme antibody conjugate. The intensity of the spot can be assessed visually within the sampler to ascertain the presence or absence of captured enzyme, or alternatively quantitative results can be obtained using an optical scanner. The limit of detection is 5 ng per filter for subtilisin (20 ng for visual discrimination between this standard and the zero). The assay is stable to the effects of ambient air sampling at 31 min(-1) for 18 h.

Air Pollution, Indoor↗

PubMed2002

LC-electron capture APCI-MS for the determination of nitroaromatic compounds.

The determination of selected nitroaromatic compounds in liquid chromatography-mass spectrometry with electron capture (EC) ionisation using a commercial atmospheric pressure chemical ionisation (APCI) interface in the negative mode is described. The electron capture effect is observed for nitroaromatics which do not easily undergo deprotonation under these conditions. Depending on the structure of the analytes, either dissociative or, for the first time in LC-MS, non-dissociative electron capture is observed. Limits of detection and linear range for the determination of the analytes match those obtained for nitroaromatics which undergo deprotonation. The investigated substances comprise numerous substituted nitrobenzenes and nitrobenzooxadiazoles.

Journal Article↗

PubMed2003

LC-electron capture-APCI(-)-MS determination of nitrobenzoxadiazole derivatives.

Nitrobenzoxadiazole (NBD) derivatives are determined with limits of detection ranging down to 20 nmol l(-1) using liquid chromatography-mass spectrometry (LC-MS) with electron capture (EC) ionisation. An atmospheric pressure chemical ionisation (APCI) interface operated in the negative ion mode is used as ionisation source. Amine derivatives of 4-chloro-7-nitro-2,1,3-benzoxadiazole (NBDCl) as well as the isocyanate derivatives of 4-nitro-7-piperazino-2,1,3-nitrobenzoxadiazole (NBDPZ) have been analysed using this technique. The parameters favouring electron capture mechanisms have been investigated thoroughly under consideration of the competing mechanism of deprotonation to allow a better understanding of the electron capture process and to improve selectivity of the analysis.

Chromatography, Liquid↗

PubMed2004

Molded polyethylene glycol microstructures for capturing cells within microfluidic channels.

The ability to control the deposition and location of adherent and non-adherent cells within microfluidic devices is beneficial for the development of micro-scale bioanalytical tools and high-throughput screening systems. Here, we introduce a simple technique to fabricate poly(ethylene glycol)(PEG) microstructures within microfluidic channels that can be used to dock cells within pre-defined locations. Microstructures of various shapes were used to capture and shear-protect cells despite medium flow in the channel. Using this approach, PEG microwells were fabricated either with exposed or non-exposed substrates. Proteins and cells adhered within microwells with exposed substrates, while non-exposed substrates prevented protein and cell adhesion (although the cells were captured inside the features). Furthermore, immobilized cells remained viable and were stained for cell surface receptors by sequential flow of antibodies and secondary fluorescent probes. With its unique strengths in utility and control, this approach is potentially beneficial for the development of cell-based analytical devices and microreactors that enable the capture and real-time analysis of cells within microchannels, irrespective of cell anchorage properties.

Animals↗

PubMed2005

Microfluidic capturing-dynamics of paramagnetic bead suspensions.

We study theoretically the capturing of paramagnetic beads by a magnetic field gradient in a microfluidic channel treating the beads as a continuum. Bead motion is affected by both fluidic and magnetic forces. The transfer of momentum from beads to the fluid creates an effective bead-bead interaction that greatly aids capturing. We demonstrate that for a given inlet flow speed a critical density of beads exists above which complete capturing takes place.

Magnetics↗

PubMed2003

An apparatus for electrophoretic capture and recovery of circular DNA in thin layers.

An apparatus was designed for the electrophoretic capture and recovery of circular DNA in thin layers (membranes). Rapid separations were done by the use of a low-conductivity buffer and high electric field strengths. Two methods that specifically retain circular DNA in the membranes were demonstrated using the supercoiled and open circular forms of two plasmids with sizes of 4.4 and 13 kbp. Electrophoretic trapping (by an impalement mechanism) in agarose-gel-filled membranes used electric field strength to immobilize circular DNA in the membranes. The other method of capture utilized the greatly reduced electrophoretic mobility of circular DNA in membranes composed of agarose and the linear polymer hydroxyethylcellulose. The reduction in electrophoretic mobility was not dependent upon the electric field strength, distinguishing it from electrophoretic trapping. Trapping of circular DNA in the membranes followed by size analysis using agarose-gel electrophoresis could be used as a two-dimensional separation tool for the analysis of complex mixtures. Captured DNA was recovered by two methods: (i). centrifugation of membranes made with low-melting-point agarose resulted in a gel slurry that could be heated to release the DNA; (ii). electroelution of the membranes. Electroelution was done by using an electrode that was isolated from the DNA by a 'barrier' membrane. A non-trapping electric field was used to reverse the DNA out of the membrane into a small volume of buffer above the membrane.

Adsorption↗