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Visual Detection (visual + detection)
Selected AbstractsAn Aptamer Cross-Linked Hydrogel as a Colorimetric Platform for Visual Detection,ANGEWANDTE CHEMIE, Issue 6 2010Zhi Zhu Der Gel-Sol-Übergang eines Hydrogels, in dem ein Enzym eingeschlossen ist, kann effizient durch die Bindung eines Substrats gesteuert werden. Das freigesetzte Enzym kann anschließend als Katalysator wirken und das Signal verstärken (siehe Bild). Schon 20,ng Kokain lassen sich binnen 10,min anhand eines Farbumschlags mit bloßem Auge nachweisen. [source] Marking pike fry otoliths with alizarin complexone and strontium: an evaluation of methodsJOURNAL OF FISH BIOLOGY, Issue 3 2001C. Skov Laboratory experiments demonstrated that both alizarin complexone and strontium are useful in mass marking of pike Esox lucius fry otoliths. Visual detection of alizarin complexone marks was considered more reliable than the quantitative analysis of strontium for differentiating marked and unmarked individuals after release in a Danish lake. [source] Visual detection of IS6110 of Mycobacterium tuberculosis in sputum samples using a test based on colloidal gold and latex beadsCLINICAL MICROBIOLOGY AND INFECTION, Issue 11 2006P. Upadhyay Abstract The IS6110 sequence was detected visually in sputum samples of tuberculosis patients using a bi-probe system. One of the probes was an oligonucleotide conjugated to colloidal gold particles, complementary to one end of the target strand. The other probe was an oligonucleotide conjugated to latex beads complementary to the other end of the target strand. In a reaction mix, these two probes bind to the target strand, and the latex beads are then separated by filtration. Bound latex beads have gold colloid particles at the other end of the target strand. These gold colloid particles were made visible to the naked eye by silver autometallography on the ,invisible' colloidal gold particles. The lower detection limit was 50 ng of genomic DNA of Mycobacterium tuberculosis. This new test, together with conventional PCR, was performed on DNA extracted from sputum samples of suspected tuberculosis patients. The new test was simple to perform, the results were visible to the naked eye, and the test was highly specific, as even single point mutations in the target strand sequence could be differentiated. The test could be useful in field-level laboratories because it requires no sophisticated equipment. [source] Superior detection of threat-relevant stimuli in infancyDEVELOPMENTAL SCIENCE, Issue 1 2010Vanessa LoBue The ability to quickly detect potential threat is an important survival mechanism for humans and other animals. Past research has established that adults have an attentional bias for the detection of threat-relevant stimuli, including snakes and spiders as well as angry human faces. Recent studies have documented that preschool children also detect the presence of threatening stimuli more quickly than various non-threatening stimuli. Here we report the first evidence that this attentional bias is present even in infancy. In two experiments, 8- to 14-month-old infants responded more rapidly to snakes than to flowers and more rapidly to angry than to happy faces. These data provide the first evidence of enhanced visual detection of threat-relevant stimuli in infants and hence offer especially strong support for the existence of a general bias for the detection of threat in humans. [source] Transcranial magnetic stimulation of the human frontal eye field facilitates visual awarenessEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 11 2003Marie-Hélène Grosbras Abstract What are the brain mechanisms allowing a stimulus to enter our awareness? Some theories suggest that this process engages resources overlapping with those required for action control, but experimental support for these ideas is still required. Here, we investigated whether the human frontal eye field (FEF), an area known to control eye movements, is involved in visual awareness. Volunteers participated in a backward masking task in which they were able to detect a target in a small proportion of trials. We observed that a single pulse of transcranial magnetic stimulation applied over the FEF shortly before the target's onset facilitated visual sensitivity; subjects were able to detect an otherwise subliminal object. These results show that modulating the neuronal activity of the FEF can enhance visual detection, thereby yielding new insights into the neural basis of visual awareness. [source] Hide, rest or die: a light-mediated diapause response in Daphnia magna to the threat of fish predationFRESHWATER BIOLOGY, Issue 1 2005Miros, lusarczyk Summary 1. In a laboratory batch culture experiment, a diapause response of Daphnia magna to a simulated threat of fish predation was tested at various light intensities, which under natural conditions determine potential vulnerability of Daphnia to visual planktivorous fish. 2. Under moderate light intensity (1.4 ,mol m,2 s,1) that allows effective predation by fish, the proportion of females producing dormant eggs was significantly higher than under dim light conditions (0.001 ,mol m,2 s,1) that are not favourable for visual detection of prey. Production of dormant eggs was not observed in complete darkness or in treatments missing fish kairomones, irrespective of tested light conditions. 3. The observed phenomenon is interpreted as a flexible response of prey to the conditional risk of predation assessed by Daphnia according to the presence of fish-derived cues on the one hand and the presence of dark refugia on the other. Irrespective of the presence of fish kairomones, Daphnia may not produce resting eggs as long as a safe, dark, bottom zone is accessible. [source] Beta diversity of frogs in the forests of New Guinea, Amazonia and Europe: contrasting tropical and temperate communitiesJOURNAL OF BIOGEOGRAPHY, Issue 5 2009Chris Dahl Abstract Aim, To test the hypothesis that animal communities within environmentally relatively uniform lowland forests are characterized by low beta diversity, both in tropical and in temperate areas. Location, Lowland forests in the basins of the Sepik and Ramu rivers in New Guinea, the Amazon river in Bolivia, and the Elbe and Dyje rivers in the Czech Republic. Methods, A network of 5,6 study sites spanning distances from 20,80 to 300,500 km in each study area was systematically surveyed for all frogs, using visual detection and call tracking. The community data were analysed for alpha and beta diversity. Results, Local (alpha) diversity of frog communities was similar in the two tropical areas, New Guinea (mean ± SE of 22 ± 1.4 species per site) and Amazonia (24 ± 1.7 species), but was significantly lower in Europe (8 ± 0.8 species). In Amazonia, 36 of the total of 70 species were recorded from single sites. In contrast, widespread species dominated in Europe, whereas New Guinea exhibited an intermediate pattern with both local and widespread species well represented. The rate of species accumulation across different sites was lowest in Europe, intermediate in New Guinea and highest in Amazonia. The regional species diversity, expressed as the combined number of species from five study sites, was 1.5 times higher than the local species diversity at a single site in Europe, 2.0 times higher in New Guinea and 2.7 times higher in Amazonia. The proportion of species shared between communities decreased with geographic distance in New Guinea and Europe, but not in Amazonia. Main conclusions, Frog communities in the lowland tropical rain forests of New Guinea and Amazonia had similar numbers of species, but differed in their beta diversity. More species in Amazonia had restricted distributions than in New Guinea. Both tropical areas had markedly higher alpha and beta diversity than the temperate area in Europe. [source] | ||||||||||