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LENE J. KJÆR ERIC M. SCHAUBER CLAYTON K. NIELSEN 《The Journal of wildlife management》2008,72(8):1819-1825
Abstract: White-tailed deer (Odocoileus virginianus) are important game mammals and potential reservoirs of diseases of domestic livestock; thus, diseases of deer are of great concern to wildlife managers. Contact, either direct or indirect, is necessary for disease transmission, but we know little about the ecological contexts that promote intrasexual contact among deer. Using pair-wise direct contacts estimated from Global Positioning System collar locations and joint utilization distributions (JUDs), we assessed habitats in which contacts occur to test whether direct contact rates among female white-tailed deer in different social groups differs among land-cover types. We also tested whether contact rates differed among seasons, lunar phases, and times of day. We obtained locations from 27 female deer for periods of 0.5–17 months during 2002–2006. We designated any simultaneous pair of locations for 2 deer <25 m apart as a direct contact. For each season, we used compositional analysis to compare land-cover types where 2 deer had contact to available land-cover weighted by their JUD. We used mixed-model logistic regression to test for effects of season, lunar phase, and time of day on contact rates. Contact rates during the gestation season were greater than expected from random use in forest and grassland cover, whereas contact rates during the fawning period were greater in agricultural fields than in other land-cover types. Contact rates were greatest during the rut and lowest in summer. Diel patterns of contact rates varied with season, and contact rates were elevated during full moon compared to other lunar periods. Both spatial and temporal analyses suggest that contact between female deer in different social groups occurs mainly during feeding, which highlights the potential impact of food distribution and habitat on contact rates among deer. By using methods to associate contacts and land-cover, we have created beneficial tools for more elaborate and detailed studies of disease transmission. Our methods can offer information necessary to develop spatially realistic models of disease transmission in deer. 相似文献
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Two silicone coatings have been evaluated for barnacle adhesion. One coating is an unfilled hydrosilation cured polydimethylsiloxane (PDMS) network, while the other is a room temperature vulcanized (RTV), filled, ethoxysiloxane cured PDMS elastomer, RTV11?. The adhesion strength of one species of barnacle, Balanus eburneus, to the hydrosilation coatings is in the range of 0.37–0.60 kg cm‐2 while the corresponding range for RTV11 is 0.64–0.90 kg cm‐2. The easier release of B. eburneus from the hydrosilation cured network compared to RTV11 is discussed in relationship to differences in bulk and surface properties. Preliminary results suggest bulk modulus may be the most important parameter in determining barnacle adhesion strength. In light or mechanical property analysis, a re‐evaluation of surface properties and chemical stability is presented. 相似文献
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Ulrike Herzschuh H. John B. Birks Xingqi Liu Claudia Kubatzki Gerrit Lohmann 《Global Ecology and Biogeography》2010,19(2):278-286
Aim Atmospheric CO2 concentrations depend, in part, on the amount of biomass locked up in terrestrial vegetation. Information on the causes of a broad‐scale vegetation transition and associated loss of biomass is thus of critical interest for understanding global palaeoclimatic changes. Pollen records from the north‐eastern Tibet‐Qinghai Plateau reveal a dramatic and extensive forest decline beginning c. 6000 cal. yr bp . The aim of this study is to elucidate the causes of this regional‐scale change from high‐biomass forest to low‐biomass steppe on the Tibet‐Qinghai Plateau during the second half of the Holocene. Location Our study focuses on the north‐eastern Tibet‐Qinghai Plateau. Stratigraphical data used are from Qinghai Lake (3200 m a.s.l., 36°32′–37°15′ N, 99°36′–100°47′ E). Methods We apply a modern pollen‐precipitation transfer function from the eastern and north‐eastern Tibet‐Qinghai Plateau to fossil pollen spectra from Qinghai Lake to reconstruct annual precipitation changes during the Holocene. The reconstructions are compared to a stable oxygen‐isotope record from the same sediment core and to results from two transient climate model simulations. Results The pollen‐based precipitation reconstruction covering the Holocene parallels moisture changes inferred from the stable oxygen‐isotope record. Furthermore, these results are in close agreement with simulated model‐based past annual precipitation changes. Main conclusions In the light of these data and the model results, we conclude that it is not necessary to attribute the broad‐scale forest decline to human activity. Climate change as a result of changes in the intensity of the East Asian Summer Monsoon in the mid‐Holocene is the most parsimonious explanation for the widespread forest decline on the Tibet‐Qinghai Plateau. Moreover, climate feedback from a reduced forest cover accentuates increasingly drier conditions in the area, indicating complex vegetation–climate interactions during this major ecological change. 相似文献
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Kenneth J. Lohmann 《Current biology : CB》2018,28(17):R952-R955
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