关键词： pyroelectric array sensor   segmentation   wavelets   hidden Markov tree model   expectation-maximization algorithm   scale invariant feature transform   speeded up robust features  

摘要： Linear pyroelectric array sensors have enabled useful classifications of objects such as humans and animals to be performed with relatively low-cost hardware in border and perimeter security applications. Ongoing research has sought to improve the performance of these sensors through signal processing algorithms. In the research presented here, we introduce the use of hidden Markov tree (HMT) models for object recognition in images generated by linear pyroelectric sensors. HMTs are trained to statistically model the wavelet features of individual objects through an expectation-maximization learning process. Human versus animal classification for a test object is made by evaluating its wavelet features against the trained HMTs using the maximum-likelihood criterion. The classification performance of this approach is compared to two other techniques;a texture, shape, and spectral component features (TSSF) based classifier and a speeded-up robust feature (SURF) classifier. The evaluation indicates that among the three techniques, the wavelet-based HMT model works well, is robust, and has improved classification performance compared to a SURF-based algorithm in equivalent computation time. When compared to the TSSF-based classifier, the HMT model has a slightly degraded performance but almost an order of magnitude improvement in computation time enabling real-time implementation. (C) 2015 Society of Photo-Optical Instrumentation Engineers (SPIE)

关键词： 丙型肝炎病毒   树鼩   动物模型  

摘要： 丙型肝炎病毒(HCV)感染是全球关注的公共健康问题之一。只有建立稳定可靠的HCV感染模型,才能更好地研究HCV感染慢性化和致癌的机制,从而推动丙型肝炎疫苗的研制和抗丙型肝炎药物的筛选。HCV宿主范围特别狭窄,只有人和黑猩猩对其易患。目前有一些体内和体外的实验结果初步显示,树鼩是目前继黑猩猩之后唯一能感染HCV的动物。该文对HCV感染树鼩动物模型的研究进展予以行综述。

关键词： Frogs   Earthworms   Worms   Ureter   Host specificity   Experimental infection   Ecological life histories  

摘要： Given their ubiquitous nature, it is surprising that more oligochaete annelid worms (Annelida: Clitellata) have not adopted an endoparasitic lifestyle. Exceptions, however, are the understudied members of the genus Dero (Allodero) that parasitize the ureters of tree frogs and toads. This study experimentally explores the life cycle and host specificity of Allodero hylae, the worm's use of chemical cues in host searching, and its seasonal prevalence and abundance over a year-long collection period on the Florida Southern College campus. A total of 2,005 A. hylae was collected from the ureter, urinary bladder, or expressed urine of wild Osteopilus septentrionalis;a significant positive correlation was found between host snout-vent length and parasite intensity for female but not male hosts. Monthly prevalence of A. hylae reached a peak of 58% in April, but never dropped below 20% in any month;mean abundance peaked March-May, whereas few worms were recovered in December and January. Confirming a parasitic lifestyle, wild-collected hosts with intense infections, typically >40 worms, showed obvious dilatation of the ureter wall, and some young-of-the-year O. septentrionalis exposed to A. hylae in the laboratory were killed by the apparent rupture of the host's ureter. The worm has a direct life cycle: worms expelled in the host's urine are capable of locating and re-infecting other hosts within aquatic microhabitats such as bromeliad tanks, and worms can survive for weeks in a free-living environment, even undergoing a morphological change. Further, chemotaxis assays found a positive response to a tree frog attractant for worms recently removed from hosts. Overall, this study provides the first multifaceted investigation on the life history and ecology of any Allodero spp., which offers new insights into an understudied endoparasitic oligochaete.

关键词： Extinction   Fire intensity   Fire management   Population viability analysis   Savanna   Threatened species   Simulation experiment  

摘要： Patch-mosaic burning is a widely accepted practical approach to managing biodiversity, whereby spatial and temporal diversity of fire is manipulated to benefit biotic diversity. We use simulation experiments based on stochastic population viability analysis to evaluate the implications of contrasting patch-mosaic burning scenarios for the population dynamics and risk of decline of four species of small mammals in northern Australia. Our results, based on models developed from detailed mark-recapture data, suggest that fire frequency has more influence on small-mammal persistence than fire extent. Risk of extinction increased for all four species when fire frequency exceeded once every five years. Under current ambient fire regimes most Australia tropical savannas burn more frequently and therefore seem to have unfavourable consequences for this faunal group and risk precipitating severe future declines. Crown Copyright (C) 2015 Published by Elsevier Ltd. All rights reserved.

关键词： Light trapping   light color   biting midges   vector control   light sources  

摘要： The role of the light-emitting diode (LED) modified light traps in the attraction of biting midges was evaluated in Northeastern Maranhao, Brazil. The modified traps held a 5 mm high-brightness LED bulb, one in the green (520 nm) and other in the blue (470 nm) region of the visible spectrum. The incandescent bulb was used as control. From a total of 2,764 specimens, the most frequent species were Culicoides lutzi Costa Lima (58.54%), C. paucienfuscatus Barbosa (27.30%), C. duartei Tavares and Luna Dias (4.74%) and C. insignis Lutz (4.63%). The green light source accounted for 53.87% of the sampled individuals, followed by incandescent (34.95%) and blue lights (11.18%), but these differences were not statistically significant. The differences found among the species' responses demonstrate that variances in species-specific LED attractiveness exist and the results must be individually evaluated. Even without statistical differences, it is suggested to use LEDs as an alternative for the Culicoides collections because of important advantages compared to incandescent lamps.

关键词： Mesquite   Wild ass   Invasion   India   Grasslands   Biodiversity  

摘要： Wild Ass Wildlife Sanctuary is one of the largest wildlife sanctuaries in India represents 'Indian wild ass' (Equus hemionus khur), an endangered desert mammal of the world. The present study has found desert mammals are supporting rapid invasion of Mesquite (Prosopis juliflora). Multi-temporal satellite images of 1977-2011 have been used for spatial quantification of Mesquite. The annual expansion rate of Mesquite cover has been estimated between 1.66 and 6.87 during the studied phases indicates significant threat to indigenous biodiversity.

关键词： African elephant   death   encephalomyocarditis   Loxodonta africana   virus   zoo  

摘要： A fatal case of encephalomyocarditis virus (EMCV) involving an African elephant (Loxodonta africana) occurred in November 2013 at the Reserve Africaine de Sigean, France. An adult female was found dead without any preliminary symptoms. Gross pathologic changes consisted of petechiae and hemorrhages on mucosae and internal organs, abundant transudate in the abdominal and pericardial cavities, and myocarditis. Histopathologic examination showed extensive degeneration and necrosis of ventricular cardiomyocytes with concurrent lymphoplasmocytic and eosinophilic infiltrate. An EMCV was isolated from several organs and considered the causative agent of the myocarditis. The same strain of virus was also isolated in rodents captured on zoo premises and considered to be the reservoir of the virus. To the authors' knowledge, this is the first EMCV case in a captive African elephant in Europe.

关键词： Fleas   Parasitism   Mammals   Species diversity   Rainfall   Flea infestations   Ectoparasites   Host parasite relationships   Animal communities  

摘要： The relative importance of environmental factors and host factors in explaining variation in prevalence and intensity of flea parasitism in small mammal communities is poorly established. We examined these relationships in an East African savanna landscape, considering multiple host levels: across individuals within a local population, across populations within species, and across species within a landscape. We sampled fleas from 2,672 small mammals of 27 species. This included a total of 8,283 fleas, with 5 genera and 12 species identified. Across individual hosts within a site, both rodent body mass and season affected total intensity of flea infestation, although the explanatory power of these factors was generally modest (<10%). Across host populations in the landscape, we found consistently positive effects of host density and negative effects of vegetation cover on the intensity of flea infestation. Other factors explored (host diversity, annual rainfall, anthropogenic disturbance, and soil properties) tended to have lower and less consistent explanatory power. Across host species in the landscape, we found that host body mass was strongly positively correlated with both prevalence and intensity of flea parasitism, while average robustness of a host species to disturbance was not correlated with flea parasitism. Cumulatively, these results provide insight into the intricate roles of both host and environmental factors in explaining complex patterns of flea parasitism across landscape mosaics.

关键词： Animals   Arthropods   Birds   Ethiopia   Predatory Behavior   Trees  

摘要： Bird and arthropod predation is often associated with natural pest control in agricultural landscapes, but the rates of predation may vary with the amount of tree cover or other environmental factors. We examined bird and arthropod predation in three tree-rich and three tree-poor landscapes across southwestern Ethiopia. Within each landscape we selected three tree-rich and three tree-poor homegardens in which we recorded the number of tree species and tree stems within 100 x 100 m surrounding the central house. To estimate predation rates, we attached plasticine caterpillars on leaves of two coffee and two avocado shrubs in each homegarden, and recorded the number of attacked caterpillars for 7-9 consecutive weeks. The overall mean daily predation rate was 1.45% for birds and 1.60% for arthropods. The rates of arthropod predation varied among landscapes and were higher in tree-poor landscapes. There was no such difference for birds. Within landscapes, predation rates from birds and arthropods did not vary between tree-rich and tree-poor homegardens in either tree-rich or tree-poor landscapes. The most surprising result was the lack of response by birds to tree cover at either spatial scale. Our results suggest that in tree-poor landscapes there are still enough non-crop habitats to support predatory arthropods and birds to deliver strong top-down effect on crop pests.

关键词： biotic resistance   food availability   grasslands   invasion   rodent   seed consumption  

摘要： Biotic resistance has been invoked as a major barrier to woody species invasion, although the role of resident generalist consumers and their interaction with seed availability in a local community has received little attention. We assessed tree seed consumption by rodents under two different scenarios: (i) We documented in field spatio-temporal patterns of seed predation by native rodents on two exotic tree species, Gleditsia triacanthos or honey locust' and Robinia pseudoacacia or white locust' (family Leguminosae), in five grassland habitats of the Inland Pampa, Argentina. (ii) We conducted laboratory feeding trials to evaluate tree seed consumption in the presence (cafeteria-style feeding trials) and in the absence (non-choice feeding trials) of alternative food supplies. Seed predation was generally higher for Robinia than for Gleditsia seeds, both in field and laboratory conditions. For both tree species, seed predation varied between habitats and seasons and was higher in the native tussock grassland than in the remaining studied communities, whereas the crop field showed the lowest levels of consumption along with the absence of captured rodents. Seed consumption of Gleditsia and Robinia among the four grassland communities (which did not differ in rodent abundance) was negatively associated with the availability of alternative food. Laboratory feeding trials showed a higher consumption of Gleditsia seeds in the non-choice than in the cafeteria-style feeding trials, while the consumption of Robinia seeds did not differ in the absence or presence of alternative seeds. These patterns indicate that the contribution of resident granivores to invasion resistance might depend on colonizer species identity, recipient community type and season of the year. We suggest that rodent preferences for different invader seeds will interact with the availability of alternative food in the local habitat in influencing the amount of predator-mediated biotic resistance to invas