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821.
Encephalocele is the most common cause of occipital midline extracranial mass associated with hydrocephalus. A case is presented where an occipital extracranial mass associated with hydrocephalus which was detected on second-trimester ultrasound examination turned out to be a haemangioma, a relatively benign lesion. We suggest that haemangioma should be considered in the differential diagnosis of extracranial masses detected prenatally. 相似文献
822.
Animals assess the fighting ability of conspecifics either by engaging in aggressive interactions or observing contests between others. However, whether individuals assess physical prowess outside the context of aggressive interactions remains unknown. We examined whether male green swordtails (Xiphophorus helleri) extract information about the fighting ability of solitary individuals via observation and whether acquiring such information elicits behavioral modifications. Contests preceded by mutual visual assessment were significantly shorter than fights where only one or neither of the two individuals was informed in advance. Focal animals initiated aggressive behavior more often against larger opponents only after previewing their adversary, indicating that swordtails can extract information about relative body size from watching solitary conspecifics. When a fighting disadvantage is perceived, observers adopt tactics that increase their probability of winning the contest. 相似文献
823.
Model calculating annual mean atmospheric dispersion factor for coastal site of nuclear power plant 总被引:1,自引:0,他引:1
HU Er-bang YAO Ren-tai ZHANG Mao-shuan GAO Zhan-rong WANG Shu-xian CHEN Jia-yi JIA Pei-rong Liao Qi-lin 《环境科学学报(英文版)》2001,13(3):280-290
IntroductionAnatmospheredispersionfieldexperimentwasdoneonthecoastalsiteofnuclearpowerplant (NPP)intheeastpartofChinaduring 1995— 1996 Thecontentofthisexperimentincludes:hourlyobservationofwindandtemperatureonthetowerof10 0m ;Observationofsurfacewindandseeandl… 相似文献
824.
We present a phylogeographic analysis of an abundant New Zealand endemic sea-star, Patiriella regularis, to help pinpoint the location of an important biogeographic disjunction in central New Zealand. The analysis incorporates 284 mtDNA control region sequences (approximately 800 bp) of P. regularis from 22 coastal locations around New Zealand. We detected 132 haplotypes, with a mean divergence of 0.96%. AMOVA analysis of New Zealand samples is consistent with a north-south biogeographic disjunction across central New Zealand (among-group genetic variance=6.10%; P=0.0005). Cook Strait, the shallow marine strait separating the main islands, is not correlated with the disjunction: samples from northern South Island are genetically indistinguishable from North Island samples (variance=1.69%; P=0.073). These results are consistent with the hypothesis that upwelling zones south of Cook Strait constitute a significant barrier to larval dispersal.Communicated by M.S. Johnson, Crawley 相似文献
825.
826.
E.?P.?BadásEmail author J.?Martínez J.?Rivero-de Aguilar C.?Ponce M.?Stevens S.?Merino 《Die Naturwissenschaften》2018,105(1-2):17
Carry-over effects refer to processes that occur in one season and influence fitness in the following. In birds, two costly activities, namely reproduction and moult, are restricted to a small time window, and sometimes overlap. Thus, colour in newly moulted feathers is likely to be affected by the costs of reproduction. Using models of bird vision we investigated male colour change in a free-living population of blue tits (Cyanistes caeruleus) in three sampling occasions: spring 1, winter and spring 2. We related crown, tail, breast and cheek feather colouration after the moult (winter) to the intensity of infections by blood parasites during reproduction (spring 1). In the following spring (spring 2), we explored mating patterns with respect to changes in feather colour (springs 1 vs. 2). Males that were less intensely infected by the malaria parasite Plasmodium while breeding showed purer white cheek feathers in winter, which may indicate higher feather quality. Increased brightness in the white cheek was associated with better body condition during reproduction. In the following season, males with brighter cheeks paired with females that had noticeably brighter cheek patches compared to the male’s previous mate. These results suggest that the conditions experienced during reproduction are likely to affect moult and thus feather colouration, at least in the white patch. High quality individuals may allocate resources efficiently during reproduction increasing future reproductive success through variation in mating patterns. Carry-over effects from reproduction might extend not only to the non-breeding phase, but also to the following breeding season. 相似文献
827.
828.
The movement of animals in groups is widespread in nature. Understanding this phenomenon presents an important problem in ecology with many applications that range from conservation to robotics. Underlying all group movements are interactions between individual animals and it is therefore crucial to understand the mechanisms of this social behaviour. To date, despite promising methodological developments, there are few applications to data of practical statistical techniques that inferentially investigate the extent and nature of social interactions in group movement. We address this gap by demonstrating the usefulness of a Hidden Markov Model approach to characterise individual-level social movement in published trajectory data on three-spined stickleback shoals (Gasterosteus aculeatus) and novel data on guppy shoals (Poecilia reticulata). With these models, we formally test for speed-mediated social interactions and verify that they are present. We further characterise this inferred social behaviour and find that despite the substantial shoal-level differences in movement dynamics between species, it is qualitatively similar in guppies and sticklebacks. It is intermittent, occurring in varying numbers of individuals at different time points. The speeds of interacting fish follow a bimodal distribution, indicating that they are either stationary or move at a preferred mean speed, and social fish with more social neighbours move at higher speeds, on average. Our findings and methodology present steps towards characterising social behaviour in animal groups. 相似文献
829.
L.?Burutarán A.?Lizasoain M.?García L.?F.?L.?Tort R.?Colina M.?VictoriaEmail author 《Food and environmental virology》2016,8(1):13-17
Aichivirus 1 (AiV-1) is an enteric virus with 30 nm in diameter, belonging to the genus Kobuvirus in the Picornaviridae family being a causative agent of gastroenteritis in humans. The transmission is via the fecal-oral route, through person to person contact, recreation in contaminated waters, or through the consumption of contaminated food or water. The aim of this study was to determine the frequency and the molecular characterization of AiV-1 in wastewater from Uruguay. Biweekly collections from March 2011 to February 2012 were performed in the cities of Bella Unión, Salto, Paysandú, and Fray Bentos, northwestern region of Uruguay. A total of 96 samples were collected; viruses were concentrated by ultracentrifugation, and AiV-1 was detected by using a nested PCR with primers directed to a conserved region (3CD junction) of the viral genome. A high frequency of AiV-1 (n = 54) was observed at all the cities analyzed mainly in the colder months of the year. AiV-1 was not evidenced as an appropriate viral fecal indicator since when compared with other previously detected enteric viruses, no correlation was observed. All 13 characterized AiV-1 belonged to the genotype B after the phylogenetic analysis performed with the sequences obtained from the first round PCR amplicon. This study demonstrates that AiV-1 is a frequently detected enteric viruses present in wastewater and excreted by infected persons in the northwestern region of Uruguay. 相似文献
830.
Y.?ShiEmail author T.?Zhao 《Mitigation and Adaptation Strategies for Global Change》2016,21(6):823-838
The nonferrous metal industry (NMI) of China consumes large amounts of energy and associated emissions of carbon dioxide (CO 2) are very high. Actions to reduce CO 2 emissions and energy consumption are warranted. This study aims to analyze current China NMI trends of CO 2 emissions and energy consumption including the underlying regional driver characteristics. We analyze the changes of CO 2 emissions in the NMI based on the Logarithmic Mean Divisia Index (LMDI) method from 2000 to 2011. Then, a classification system is used to study the regional differences in emission changes from the NMI. The results show that the emissions of the Chinese NMI increased rapidly at an average annual growth rate of 31 million metric tons. The economic scale and energy intensity are the main driving factors responsible for the change in the emissions, while carbon emission coefficients make only a small contribution toward decreasing the emissions, and the energy structure has a volatile effect. Emissions and energy intensity of 29 China provinces were divided into five categories. The change in the trend of each region is indicated in this paper. Hebei is one of the provinces that achieved the best performance, and Chongqing achieved the worst performance among all of the regions. The analysis suggests that the main emphasis of CO 2 emission mitigation should be focused on controlling the economic scale and improving the energy intensity. Developing the use of clean energy technologies and policies in both the NMI and power industries is important. 相似文献