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81.
82.
J. Marañón Di Leo 《Molecular simulation》2013,39(4):280-286
Using periodic boundary conditions and external electric potential field, we have simulated an ion current flow through a flexible nanopore using cations and an explicit extended simple point charge (SPC/E) water with molecular dynamics simulation. The simulation voltages range goes beyond the usual ionic channel measurements ( ± 1 V) and yields useful information about density profiles, current density distribution and current–voltage (I–V) characteristics. 相似文献
83.
Quintero E Díaz E Vargas JP Schmajuk N López JC De la Casa LG 《Behavioural processes》2011,86(2):242-249
The latent inhibition phenomenon is observed when a conditioned stimulus is preexposed without any consequence before conditioning. The result of this manipulation is a reduction in conditioned response intensity to such a stimulus. In this study, we analyse the role of context novelty/familiarity on LI modulation by changing the context using a three-stage conditioned taste aversion procedure. Experiment 1 revealed that, similar to other learning procedures, a context change between preexposure and conditioning/testing (but not between preexposure/conditioning and testing) resulted in LI attenuation when the experimental contexts were novel. Experiment 2, using animals’ home cages as one of the contexts, revealed a different pattern of results, with an unexpected increase in LI magnitude when the context change was introduced between conditioning and test stages. The Schmajuk et al. (1996) computational model explains these results in terms of the increased novelty of the conditioned stimulus during preexposure, conditioning, and testing. 相似文献
84.
We examined the importance of mixed-species flock abundance, individual bird home range size, foraging height, and foraging
patch characteristics in predicting the propensity for five Neotropical passerine bird species (Slaty Antwren, Myrmotherula schisticolor; Golden-crowned Warbler, Basileuterus culicivorus; Slate-throated Redstart, Myioborus miniatus; Wilson’s Warbler, Wilsonia pusilla; and Black-and-white Warbler, Mniotilta varia) to forage within flocks, rather than solitarily. We used study plots in primary mid-elevation forest and in shade coffee
fields in western Panama. We expected that all species would spend as much time as possible flocking, but that the social
and environmental factors listed above would limit compatibility between flock movements and individual bird movements, explaining
variability in flocking propensity both within and among species. Flocking propensity was well predicted by home range size
and flock abundance together, for four of the five species. While flock abundance was uniform across plots, home range sizes
varied among species and plots, so that home range size appeared to be the principle factor limiting flocking propensity.
Estimates of flock abundance were still required, however, for calculating flocking propensity values. Foraging height and
patch characteristics slightly improved predictive ability for the remaining species, M. miniatus. In general, individual birds tended to join flocks whenever one was available inside their home range, regardless of a flock’s
specific location within the home range. Flocking propensities of individual species were lower in shade coffee fields than
in forests, and probably vary across landscapes with variations in habitat. This variability affects the stability and species
composition of flocks, and may affect survival rates of individual species.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
85.
L. A. Moore 《Journal of Ornithology》2007,148(3):357-366
Little is known of the ecology and population dynamics of the world’s largest avian frugivore. This study investigated the
population of endangered southern cassowary at Mission Beach, northeast Australia, and examined the problems associated with
determining population size and density of this keystone species. Using the results of an intensive field survey aimed at
estimating absolute numbers of individual cassowaries, the appropriate sampling methodology for rare and elusive species was
explored. Approximately 102 km2 of rainforest was surveyed using 346 km of search transects. Of a total of 110 cassowaries, there were 49 adults (28 male,
19 female, 2 unknown), 28 subadults, 31 chicks, and 2 independent birds of unknown status. This is approximately 35% of the
adult population previously estimated for the Mission Beach area. Overall adult cassowary density was 0.48 adults/km2; the density of independent birds, i.e. adults and subadults, was 0.78 birds/km2. Mean indicative home range (IHR) for adult females and males was 2.13 and 2.06 km2, respectively. Mean IHR of subadults was smaller at 0.95 km2. It was concluded that the previous practice of surveying small areas at Mission Beach (<4 km2) has led to consistent overestimation of cassowary population density, up to six times its real number. It is shown that
a sample plot between 5 and 15 km2 is necessary to approximate true cassowary density. These findings have significant application to the conservation of cassowaries
in New Guinea and in the Wet Tropics World Heritage Area of Australia. 相似文献
86.
Alexandre L. Godinho Boyd Kynard Hugo P. Godinho 《Environmental Biology of Fishes》2007,80(4):421-433
Surubim, Pseudoplatystoma corruscans, is the most valuable commercial and recreational fish in the São Francisco River, but little is known about adult migration and spawning. Movements of 24 females (9.5–29.0 kg), which were radio-tagged just downstream of Três Marias Dam (TMD) at river kilometer 2,109 and at Pirapora Rapids (PR) 129 km downstream of TMD, suggest the following conceptual model of adult female migration and spawning. The tagged surubims used only 274 km of the main stem downstream of TMD and two tributaries, the Velhas and Abaeté rivers. Migration style was dualistic with non-migratory (resident) and migratory fish. Pre-spawning females swam at ground speeds of up to 31 km day-1 in late September–December to pre-spawning staging sites located 0–11 km from the spawning ground. In the spawning season (November–March), pre-spawning females migrated back and forth from nearby pre-spawning staging sites to PR for short visits to spawn, mostly during floods. Multiple visits to the spawning site suggest surubim is a multiple spawner. Most post-spawning surubims left the spawning ground to forage elsewhere, but some stayed at the spawning site until the next spawning season. Post-spawning migrants swam up or downstream at ground speeds up to 29 km day-1 during January–March. Construction of proposed dams in the main stem and tributaries downstream of TMD will greatly reduce surubim abundance by blocking migrations and changing the river into reservoirs that eliminate riverine spawning and non-spawning habitats, and possibly, cause extirpation of populations. 相似文献
87.
Jianbo Li Chunyuan Chen Yuwei Chen Zhenhua Li Wenfu Xie Xin Zhang Mingfei Shao Min Wei 《Liver Transplantation》2019,9(42)
Lithium–sulfur (Li–S) batteries have attracted increasing attention due to their extremely high theoretical specific capacity and a promising power density. However, practical applications of Li–S batteries are still limited by the relatively low performance, owing to poor conductivity of sulfur itself and discharge products (Li2S/Li2S2) as well as the shuttle effect of the intermediate polysulfide. Herein, honeycomb‐like mesoporous Co, N‐doped carbon nanosheets (MC‐NS) with a high specific surface area and abundant defects are developed which, simultaneously enable polysulfide confinement and highly efficient conversion. Moreover, density functional theory calculations and experiments show that the Co‐N‐C catalytic site as well as defects on the carbon skeleton of the MC‐NS facilitate high efficiency in suppressing the shuttle effect of polysulfides. In situ Raman spectra further demonstrate the enhancement of adsorption ability and conversion efficiency of polysulfides on this host. As a result, the MC‐NS enables much increased specific capacity and cycling stability of Li–S batteries. This work provides a useful strategy for realizing practical applications of high‐performance Li–S batteries. 相似文献
88.
Behavioural responses in a net restraint test predict interrenal reactivity in Arctic charr Salvelinus alpinus
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C. Magnhagen T. Backström Ø. Øverli S. Winberg J. Nilsson M. A. Vindas E. Brännäs 《Journal of fish biology》2015,87(1):88-99
In this study, a 1 min net restraint test was evaluated as a method to predict stress‐coping style in Arctic charr Salvelinus alpinus, by investigating the relationship between behaviour during the test and levels of plasma cortisol sampled after 30 min confinement. In two separate groups of S. alpinus, general linearized model revealed significant correlations between cortisol levels and principal component scores extracted from principal component analysis, combining measures of activity in the tests. With the use of glmulti, the model selection ruled out any effects of size, sex and order of capture on interrenal reactivity. In general, S. alpinus that were more active in the net restraint test also had low levels of circulating cortisol, suggesting a proactive coping style. The results from two repeated runs were not correlated, but both runs, performed eight days apart, show a negative correlation between post‐stress cortisol level and activity in the net. The lack of consistency could be explained by different treatments before each run and individual differences in behavioural plasticity. The net restraint test is thus predictive of stress‐coping style in S. alpinus, and has the benefit of being less time‐consuming than the commonly used confinement stress test. 相似文献
89.
Jun Yan Yung-wei Chen Kirstin Lawrence-Apfel Isaac M. Ortega Vladimir Pozdnyakov Scott Williams Thomas Meyer 《Population Ecology》2014,56(2):401-415
Animal movements are of great importance in studying home ranges, migration routes, resource selection, and social interactions. The Global Positioning System provides relatively continuous animal tracking over time and long distances. Nevertheless, the continuous trajectory of an animal’s movement is usually only observed at discrete time points. Brownian bridge models have been used to model movement of an animal between two observed locations within a reasonably short time interval. Assuming that animals are in perpetual motion, these models ignore inactivity such as resting or sleeping. Using the latest developments in applied probability, we propose a moving–resting process model where an animal is assumed to alternate between a moving state, during which it moves in a Brownian motion, and a resting state, during which it does not move. Theoretical properties of the process are studied as a first step towards more realistic models for animal movements. Analytic expressions are derived for the distribution of one increment and two consecutive increments, and are validated with simulations. The induced bridge model conditioning on the starting and end points is used to compute an animal’s probability of occurrence in an observation area during the time of observation, which has wide applications in wildlife behavior research. 相似文献
90.
《Basic and Applied Ecology》2014,15(2):179-186
Invasive rats on oceanic islands impact a large number of native species. Control programmes, and in many cases complete eradication, are used to alleviate these impacts. Basic data on rodent biology facilitate the design of control or eradication programmes, and is particularly required for programmes on tropical islands where such data are missing. Here we test for interactive effects of habitat and season that may alter black rat (Rattus rattus) space use dynamics and inform rodent management on two tropical islands. Five years of summer and winter trapping data were analysed using spatially explicit capture–recapture to calculate rat space-use and overlap, coupled with spool and line experiments ground-truthing microhabitat use. Variation in individual rat space use is primarily driven by sex and bottom-up trophic effects of seasonal rainfall on food resources, but is altered by island-specific contexts. In the absence of other introduced mammals, rats tend to have stable range overlap throughout the year but home range sizes fluctuate seasonally with rat density. The presence of other introduced mammals causes predictable greater seasonal fluctuations in rat space-use, putatively a behavioural adjustment to feral cats (Felis catus) diet-switching to rats from seasonal influxes of their alternative seabird prey. We identify winter as the recommended treatment period on both islands and discuss bait broadcast strategies. 相似文献