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101.
Attention and the detectability of weak taste stimuli 总被引:2,自引:1,他引:1
Subjects detected weak solutions of sucrose or citric acid under conditions
in which attention was directed toward one of the tastants or the other.
Detection thresholds were measured using an adaptive, forced-choice
procedure, with a three-down one-up rule, which computer simulations
suggest should be more reliable than the popular two-down one-up rule. The
thresholds were modestly but systematically lower for attended tastants
than for unattended ones. Similar results have been reported in other sense
modalities, including vision (greater sensitivity to stimuli presented to
attended versus unattended spatial locations) and hearing (greater
sensitivity to stimuli presented at attended versus unattended sound
frequencies). Taken together, the findings are consistent with a general
hypothesis regarding attention in sensory systems: gains or losses in
detectability occur when a central attentional mechanism (or, conceivably,
a preattentive mechanism) selectively and preferentially monitors signals
arising from particular subsets of peripheral neural inputs.
相似文献
102.
103.
Our experiment involved seven panels and six chocolates – five dark chocolates and one milk chocolate. The aim of the study was to compare the sensory profiles of the chocolates. A natural question to ask is “Did the panelists detect any differences among the five dark chocolates or did they systematically contrast them with the milk chocolate?” The scatter plot of the chocolates obtained by principal component analysis was useless to answer that question, because of the proximity of the points. To overcome that, we used confidence ellipses calculated using bootstrap. The originality of the study lies in the fact that we applied those ellipses to hierarchical multiple factor analysis (HMFA): among the seven panels, six were composed of trained professionals and the last one was composed of untrained students, and through that method, we managed to compare the two types of panels and balance the role of each trained panel. HMFA provides in a single scatter plot a representation of the six chocolates for each panel, the trained panels and all the panels. Confidence ellipses around each chocolate show that the combined panels – the six trained panels and also the untrained panel – differentiate the five dark chocolates. They also show how much larger the untrained panel's variability is than that of the trained panels, and how comparable are the trained panels' variability to each other. 相似文献
104.
105.
America G. Valiente Francis Juanes Eva Garcia-Vazquez 《Environmental Biology of Fishes》2005,74(3-4):323-334
Synopsis We investigated the relationship between conservation status and genetic variability in European and North American Atlantic
salmon, Salmo salar, populations, many of which have suffered severe bottlenecks. A negative north--south cline exists for the status of population
conservation in this species. A literature review of genetic variability and demographic parameters of wild Atlantic salmon
populations resulted in no statistical associations between population conservation status and genetic variation at enzyme
or VNTR loci. We found however, a negative relationship between male parr maturation rates and geographical latitude for both
American and European populations. The increase in effective population size due to participation by mature male parr and
the increased proportions of these males in smaller (southern) populations could explain the lack of expected relationship
between genetic variation and conservation status. 相似文献
106.
The spread of infectious diseases at the global scale is mediated by long-range human travel. Our ability to predict the impact of an outbreak on human health requires understanding the spatiotemporal signature of early-time spreading from a specific location. Here, we show that network topology, geography, traffic structure and individual mobility patterns are all essential for accurate predictions of disease spreading. Specifically, we study contagion dynamics through the air transportation network by means of a stochastic agent-tracking model that accounts for the spatial distribution of airports, detailed air traffic and the correlated nature of mobility patterns and waiting-time distributions of individual agents. From the simulation results and the empirical air-travel data, we formulate a metric of influential spreading--the geographic spreading centrality--which accounts for spatial organization and the hierarchical structure of the network traffic, and provides an accurate measure of the early-time spreading power of individual nodes. 相似文献
107.
JÉRÔME MUNZINGER 《Botanical journal of the Linnean Society. Linnean Society of London》2001,137(1):91-97
While working on a treatment of Violaceae for the Flore de Nouvelle-Caledonie et dependences , two new species were recognized, Agatea veillonii Munzinger and A. lecointei Munzinger. These species are here described and illustrated. Some taxonomic notes and a regional identification key are provided. 相似文献
108.
Frederick S. Scharf Jeffrey A. Buckel Francis Juanes David O. Conover 《Environmental Biology of Fishes》1997,49(3):377-388
Knowledge of prey sizes consumed by a predator aids in the estimation of predation impact. Young-of-the-year bluefish, Pomatomus saltatrix, attack their prey tail-first and often bite their prey in half; this poses a unique problem in determining prey sizes from stomach content analysis. We developed a series of linear regressions to estimate original prey lengths from measurements of eye diameter and caudal peduncle depth for striped bass, Morone saxatilis, bay anchovy, Anchoa mitchilli, American shad, Alosa sapidissima, blueback herring, Alosa aestivalis, Atlantic silverside, Menidia menidia, and white perch, Morone americana. We then used these regressions to estimate original prey sizes from pieces of prey found in stomachs of bluefish collected in the Hudson River estuary from 1990–1993. Lengths of prey that were swallowed whole were compared to estimated lengths of prey that were consumed in pieces. Lengths of prey that were consumed in pieces were larger than prey that were consumed whole. We determined the prey length/predator length ratio at which bluefish began shifting from swallowing their prey whole to partial consumption. Shifting occurred at a ratio of approximately 0.35 irrespective of prey species, suggesting that prey length plays an important role in predator foraging decisions and may contribute to gape limitations. Shifts in foraging mode effectively reduce gape limitation and allow bluefish to consume larger prey sizes which may increase their effect on prey populations. 相似文献
109.
110.
中国木薯乙醇的资源潜力及其空间分布 总被引:3,自引:0,他引:3
利用气候、土壤、地形和土壤等数据,运用ArcGIS的空间叠加分析功能,分析了中国木薯乙醇的分布生产潜力及空间分布.结果表明:中国适宜木薯分布的区域主要在广西、广东、福建、云南、江西和海南等广大南部地区,这些地区的木薯乙醇生产潜力也最高;适宜木薯种植的未利用地面积较少,仅有1.53×104hm2,其乙醇生产潜力仅能满足目前中国E10汽油约1.0%的乙醇需求量;要满足中国目前E10汽油的全部乙醇需求,需要扩大目前木薯总种植耕地面积的4.4~5.7倍,而中国的粮食安全需求则限制了该目标的实现;中国木薯乙醇满足未来生物乙醇的需求前景不容乐观,中国木薯乙醇企业的发展规划要充分考虑原料的可获性,切不可盲目扩大生产. 相似文献