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111.
通过收集网络文本分析游客对旅游目的地形象的评价和感受,运用数据挖掘的手段得到游客感知目的地形象的属性与特征,已成为旅游形象研究的重要途径。本研究以携程旅行网(www.ctrip.com)上发表的韶山游记作为样本,使用Rost Content Mining内容挖掘软件得到游客感知的韶山旅游目的地形象的属性特征,运用内容分析法,建立分析类目。在此基础上,分别对建立的四个分析类目进行分析,探索游客对韶山旅游目的地形象的感知,并就游客对韶山旅游目的地形象的感知进行归纳和分析,由此,得出互联网传播的游客对韶山旅游目的地形象感知的结论。 相似文献
112.
Keith W. Sockman Jack Weiss Michael S. Webster Vanessa Talbott Hubert Schwabl 《Behavioral ecology and sociobiology》2008,62(4):617-625
Maternally derived androgen hormones concentrate in avian egg yolks as the yolks grow on the female’s ovary, possibly forming
a basis for important maternal effects in birds. In the American kestrel (Falco sparverius), experimental elevation of yolk androgens in the first-laid egg of a clutch (a-egg) to the concentrations found naturally
in a clutch’s later-laid eggs reduces the growth rate of a-egg nestlings compared to controls. These findings, together with
discoveries from other species that the effects of yolk androgens on growth of female nestlings may differ from their effects
on growth of male nestlings, raise the hypothesis that natural changes in yolk-androgen concentrations with laying order are
ultimately due to a difference between the sexes in their yolk-androgen sensitivity and between early- and late-laid eggs
in their sex ratio. By re-analyzing previously published data and adding to the analysis data from previously unanalyzed blood
samples used for sex determination, we investigated possible sex-specific effects of yolk-androgens in the context of a potential
sex-biased laying order in free-living American kestrels. We used a multi-level, mixed model with a Gompertz function to analyze
growth of nestlings hatching from a-eggs that were control-treated or in which we experimentally elevated yolk-androgen concentrations
shortly after laying to the higher concentrations naturally found in later-laid eggs. We discovered that male nestlings were
more susceptible than female nestlings to growth inhibition by yolk-androgen elevation but did not find a bias in sex ratio
with respect to laying order. Together, these findings do not support the above hypothesis. However, they are consistent with
the hypothesis that sex differences in yolk-androgen sensitivity enable mothers to economically tune reproductive effort to
an individual offspring’s reproductive value, which can vary more for one sex than the other. 相似文献
113.
Vanessa L. Bonanno Albrecht I. Schulte-Hostedde 《Behavioral ecology and sociobiology》2009,63(6):835-846
Sperm competition is widespread in mammals and occurs when ejaculates from two or more males compete within the female’s reproductive
tract to fertilize the ova. Enlarged testes are associated with sperm competition because they produce sperm, but the accessory
glands produce fluids and proteins that are also important for fertilization success. Sperm morphology can also have consequences
for fertilization success because of its influence on sperm motility. Red squirrels engage in multiple mating, and thus sperm
competition is likely. Here, we assess levels of multiple paternity in a natural population of red squirrels, test the prediction
that testis size is correlated with size of the accessory glands and sperm morphometry, and test the prediction that ejaculate
investment is condition-dependent. Five of six litters (83%) showed evidence of multiple paternity, indicating that sperm
competition is likely to have occurred. Testis size was correlated with the size of all three accessory glands (prostate,
seminal vesicle, epididymides), and there was a generally positive relationship between the size of the accessory glands and
sperm length. Sperm morphology showed significant variation in size and shape among individual male squirrels. There was no
evidence of condition dependence of testis size or the size of the accessory glands, but sperm midpiece length was negatively
related to body condition. Further work should include determining the fitness consequence of variation in sperm morphometry,
testis size, and accessory gland size, and determining the effects of variation in ejaculate investment on sperm motility. 相似文献
114.
Cargnelutti D Tabaldi LA Spanevello RM de Oliveira Jucoski G Battisti V Redin M Linares CE Dressler VL de Moraes Flores EM Nicoloso FT Morsch VM Schetinger MR 《Chemosphere》2006,65(6):999-1006
In this study, the effects of exogenous mercury (HgCl(2)) on time-dependent changes in the activities of antioxidant enzymes (catalase and ascorbate peroxidase), lipid peroxidation, chlorophyll content and protein oxidation in cucumber seedlings (Cucumis sativus L.) were investigated. Cucumber seedlings were exposed to from 0 to 500microM of HgCl(2) during 10 and 15 days. Hg was readily absorbed by growing seedlings, and its content was greater in the roots than the in shoot. Time and concentration-dependent reduction in root and shoot length was observed at all concentrations tested, equally in the roots and shoot, at both 10 and 15 days. At 50microM HgCl(2), root fresh weight of 15-day-old seedlings increased, and at other concentrations, it reduced. For 10-day-old seedlings, reduction in root and shoot fresh biomass was observed. At 15 days, only at 50microM HgCl(2) was there no observed reduction in shoot fresh biomass. Dry weight of roots increased at 500microM both at 10 and 15 days, though at 250microM HgCl(2) there was only an increase at 15 days. There was a significant effect on shoot dry weight at all concentrations tested. Hg-treated seedlings showed elevated levels of lipid peroxides with a concomitant increase in protein oxidation levels, and decreased chlorophyll content when exposed to between 250 and 500microM of HgCl(2). At 10 days, catalase activity increased in seedlings at a moderately toxic level of Hg, whereas at the higher concentration (500microM), there was a marked inhibition. Taken together, our results suggest that Hg induces oxidative stress in cucumber, resulting in plant injury. 相似文献
115.
Christine Vanessa Schmidt Sabine Frohschammer Alexandra Schrempf Jürgen Heinze 《Die Naturwissenschaften》2014,101(1):69-72
Mother–son mating (oedipal mating) is practically non-existent in social Hymenoptera, as queens typically avoid inbreeding, mate only early in life and do not mate again after having begun to lay eggs. In the ant genus Cardiocondyla mating occurs among sib in the natal nests. Sex ratios are extremely female-biased and young queens face the risk of remaining without mating partners. Here, we show that virgin queens of Cardiocondyla argyrotricha produce sons from their own unfertilized eggs and later mate with them to produce female offspring from fertilized eggs. Oedipal mating may allow C. argyrotricha queens to found new colonies when no mating partners are available and thus maintains their unusual life history combining monogyny, mating in the nest, and low male production. Our result indicates that a trait that sporadically occurs in solitary haplodiploid animals may evolve also in social Hymenoptera under appropriate ecological and social conditions. 相似文献
116.
Jesus Rodriguez-Manzano Ayalkibet Hundesa Byron Calgua Anna Carratala Carlos Maluquer de Motes Marta Rusiñol Vanessa Moresco Ana Paula Ramos Fernando Martínez-Marca Miquel Calvo Celia Regina Monte Barardi Rosina Girones Sílvia Bofill-Mas 《Food and environmental virology》2014,6(1):31-41
Shellfish complying with European Regulations based on quantification of fecal bacterial indicators (FIB) are introduced into markets; however, information on viruses, more stable than FIB, is not available in the literature. To assess the presence of noroviruses (NoVs) GI and GII and human adenoviruses (HAdV) in domestic and imported mussels and clams (n = 151) their presence was analyzed during winter seasons (2004–2008) in north-west Spanish markets through a routine surveillance system. All samples tested negative for NoV GI and 13 % were positive for NoV GII. The role of HAdV as viral indicator was evaluated in 20 negative and 10 positive NoV GII samples showing an estimated sensitivity and specificity of HAdV to predict the presence of NoV GII of 100 and 74 % (cut-off 0.5). The levels of HAdV and NoVs and the efficiency of decontamination in shellfish depuration plants (SDP) were evaluated analyzing pre- and post-depurated mussels collected in May–June 2010 from three different SDP. There were no statistically significant differences in the prevalence and quantification of HAdV between pre- and post-depurated shellfish and between seawater entering and leaving the depuration systems. Moreover, infectious HAdV were detected in depurated mussels. These results confirm previous studies showing that current controls and depuration treatments limiting the number of FIB do not guarantee the absence of viruses in shellfish. 相似文献
117.
Integral quantities, wind run, S, and recirculation factor, R, useful for describing air flow, are calculated and combined with CO2 mixing ratios. Meteorological observations were obtained from a RASS sodar and CO2 mixing ratios from a continuous analyzer installed at a rural site in the upper Spanish plateau. The measuring campaign spread
over 3 years and two approaches were followed. The first approach considered integral quantities on a daily basis and two
classifications of air flow, to date scarcely used. The first classification distinguished among stagnation, recirculation,
and ventilation, the second considering synoptic, meso-, and local scales. Moreover, 52.94% of daily values handled in this
paper corresponded to ventilation and 49.70% to synoptic scale. The main goal of this approach is the subsequent link between
the two classifications: the synoptic scale was associated with ventilation, mesoscale with recirculation and local scale
partially with recirculation. CO2 observations were distributed in air flow groups following these classifications and mesoscale processes were satisfactorily
described since noticeable evidence of transport from nearby cities was observed. In the second approach, S and R pairs were used and CO2 mixing ratios were distributed following percent intervals of ventilation, calculated by binning these pairs. The main goal
of the second approach is to consider only three groups of mixing ratios. In the first group, with high ventilation, mixing
ratios were low. With intermediate ventilation, mixing ratios were medium, and with low ventilation mixing ratios were high.
A contrast of 21 ppm between the third and first groups was obtained at the 95th percentile. Finally, the second group provided
a contrast of 3 ppm between north and south directions and also between east and west attributed to transport from nearby
cities. 相似文献
118.
Thomas Connor Maiju Qiao Kim Scribner Jindong Zhang Vanessa Hull Wenke Bai Ashton Shortridge Rengui Li Hemin Zhang Jianguo Liu 《Conservation biology》2022,36(2):e13828
The relationships between habitat amount and fragmentation level and functional connectivity and inbreeding remain unclear. Thus, we used genetic algorithms to optimize the transformation of habitat area and fragmentation variables into resistance surfaces to predict genetic structure and examined habitat area and fragmentation effects on inbreeding through a moving window and spatial autoregressive modeling approach. We applied these approaches to a wild giant panda population. The amount of habitat and its level of fragmentation had nonlinear effects on functional connectivity (gene flow) and inbreeding. Functional connectivity was highest when approximately 80% of the surrounding landscape was habitat. Although the relationship between habitat amount and inbreeding was also nonlinear, inbreeding increased as habitat increased until about 20% of the local landscape contained habitat, after which inbreeding decreased as habitat increased. Because habitat fragmentation also had nonlinear relationships with functional connectivity and inbreeding, we suggest these important responses cannot be effectively managed by minimizing or maximizing habitat or fragmentation. Our work offers insights for prioritization of protected areas. 相似文献
119.
120.
While scholars have demonstrated that emotions play a central role in cognition, behavior, and decision making, most of the studies on emotions in work contexts show that emotions, or their expression, are often suppressed. We thus investigated how workers in high-stress work environments deal with emotions and remain functional by focusing on the range of extrinsic regulation strategies used by workers in these environments. Drawing from participant observations and in-depth, semistructured interviews, we show how police officers are flexible in their choices of emotion-regulation strategies and how contextual factors emerge as the crux of this process. We contribute to the understanding of regulatory flexibility—defined as the process of matching emotion regulation strategies to environmental circumstances as they unfold in real work situations—by identifying two main enabling factors: coregulation and third party interference. 相似文献