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761.
Jan David Lucy Vojtová Karel Bednařík Jiří Kučerík Milada Vávrová Josef Jančář 《Environmental Chemistry Letters》2010,8(4):381-385
To prepare materials with improved recycling capability, new flexible biodegradable polyurethane foams, in which non-degradable polyether polyol was partly substituted by the bio-polyols based on cellulose or starch derivatives were synthesized. The incorporation of bio-polyols into the foams’ structures as well as their influence on the foam thermal stability was assessed by Fourier-transformed infrared spectroscopy and thermogravimetric analysis analyses. The ecotoxicological aspects of the newly synthesized foams were investigated by extracting the samples using freshwater as a solvent followed by applying the microbiotest screening toxkit under trade name “Thamnotoxkit F?” with larvae of freshwater shrimps Thamnocephalus platyurus. 相似文献
762.
Ciannelli L Knutsen H Olsen EM Espeland SH Asplin L Jelmert A Knutsen JA Stenseth NC 《Ecology》2010,91(10):2918-2930
Until the last decade it was assumed that most marine species have pronounced gene flow over vast areas, largely because of their potential for dispersal during early life stages. However, recent genetic, modeling, and field studies have shown that marine populations may be structured at scales that are inconsistent with extensive dispersal of eggs and larvae. Such findings have stimulated the birth of new studies explaining the mechanisms that promote population structure and isolation in the oceans, in the face of high potential for dispersal. Here we study the vertical and horizontal distribution of cod (Gadus morhua) eggs in relation to small-scale circulation and water column hydrography in a coastal location of southern Norway. Previous studies conducted in this region have shown that cod populations inhabiting fjord locations, which are on average 30 km apart, are genetically differentiated, a remarkable outcome considering that Atlantic cod have pelagic egg stages and long pelagic larval duration. We document that cod eggs are found in greater abundance in shallow water layers, which on average are flowing up the fjord (away from the open ocean), and in the inner portion of the fjord, which is subject to lower current speeds compared to the outer or mouth of the fjord. Eggs were found to be neutrally buoyant at shallow depths, a trait that also favors local retention, given the local circulation. The same patterns held during two environmentally contrasting years. These results strongly suggest that population structure of Atlantic cod is favored and maintained by a balance between water circulation and egg characteristics. 相似文献
763.
Vedder O Magrath MJ Niehoff DL van der Velde M Komdeur J 《Behavioral ecology and sociobiology》2012,66(4):603-612
Although functional explanations for female engagement in extra-pair copulation have been studied extensively in birds, little
is known about how extra-pair paternity is linked to other fundamental aspects of avian reproduction. However, recent studies
indicate that the occurrence of extra-pair offspring may generally decline with laying order, possibly because stimulation
by eggs induces incubation, which may suppress female motivation to acquire extra-pair paternity. Here we tested whether experimental
inhibition of incubation during the laying phase, induced by the temporary removal of eggs, resulted in increased extra-pair
paternity, in concert with a later cessation of laying, in blue tits (Cyanistes caeruleus). As expected, experimental females showed a more gradual increase in nocturnal incubation duration over the laying phase
and produced larger clutches than controls. Moreover, incubation duration on the night after the first egg was laid predicted
how extra-pair paternity declined with laying order, with less incubation being associated with more extra-pair offspring
among the earliest eggs in the clutch. However, incubation duration on this first night was unrelated to our experimental
treatment and independent of final clutch size. Consequently, the observed decline in extra-pair paternity with laying order
was unaffected by our manipulation and larger clutches included proportionally fewer extra-pair offspring. We suggest that
female physiological state prior to laying, associated with incubation at the onset of laying, determines motivation to acquire
extra-pair paternity independent of final clutch size. This decline in proportion of extra-pair offspring with clutch size
may be a general pattern within bird species. 相似文献
764.
Loretta Müller Pierre Comte Jan Czerwinski Markus Kasper Andreas C.R. Mayer Adrian Schmid 《毒物与环境化学》2013,95(1):164-180
The aim of this study was to compare the cytotoxicity and the (pro-)inflammatory responses of two-stroke (direct injection and carburetor technology) and four-stroke scooter and diesel car exhaust emissions on lung cells in vitro. This was analyzed by exposing a 3D in vitro model of the epithelial airway (consisting of human bronchial epithelial cells (cell line 16HBE14o?) combined with human whole blood monocyte-derived macrophages and dendritic cells) to physically characterized exhaust emissions. Biological endpoints of cytotoxicity (lactate dehydrogenase release), as well as pro-inflammatory cytokine (tumor necrosis factor (TNF)-α) and inflammatory chemokine (interleukin(IL)-8) stimulation were examined. Two-stroke direct injection scooter exhaust contained the highest particle number concentration and nitrogen oxides (NO x ) concentrations and the emissions from the two-stroke carburetor scooter contained the highest hydrocarbon and lowest NO x concentrations. The four-stroke scooter emitted the highest carbon monoxide concentration whereas the cars emitted the lowest. The combination of various technical optimizations for the two-stroke direct injection scooter (particle filter, oxidative catalyst, better oil and fuel) reduced the total emissions strongly and the TNF-α concentration significantly (p?0.05). The cytotoxicity and the IL-8 concentration showed strong tendencies to be reduced. The analysis of the emissions of all tested two-stroke, four-stroke scooters and diesel cars showed a strong association between the adverse effects and the particle number concentration. 相似文献
765.
Pollution history revealed by sedimentary records: a review 总被引:1,自引:0,他引:1
766.
Emily R. A. Cramer Terje Laskemoen Oddmund Kleven Katie LaBarbera Irby J. Lovette Jan T. Lifjeld 《Behavioral ecology and sociobiology》2013,67(11):1845-1853
Postcopulatory sexual selection (PCSS) in internally fertilizing vertebrates is a topic of great interest, yet relatively little is known about the characteristics of sperm and ejaculates that confer an advantage in PCSS. In this study, we investigated several measures of sperm morphology that potentially contribute to fertilization success under PCSS. We tested whether sperm morphology related to success in PCSS (via extra-pair paternity) in house wrens (Troglodytes aedon). We found no evidence that sperm morphology differed between extra-pair sires and the within-pair males they cuckolded, nor that sperm morphology correlated with the proportion of within-pair offspring sired, the number of extra-pair offspring sired, or the total annual reproductive success. Male behavioral strategies may affect the probability that their sperm compete with other males’ sperm and that their sperm succeed under competition. Effects of these behavioral strategies, as well as differences between males in sperm number, could mask the effects of sperm morphology on the outcome of PCSS. Despite moderate levels of extra-pair paternity, selection on sperm may be relatively weak in house wrens. Further work is needed to understand general patterns in how sperm morphology relates to fertilization success within species. 相似文献
767.
Among nonhuman primates, male reproductive skew (i.e., the distribution of reproductive success across males) appears to be affected primarily by receptive synchrony and the number of males per group. These factors have been assumed to depend on reproductive seasonality, with strong seasonality increasing receptive synchrony, which in turn reduces the strength of male monopolization associated with more males and lower skew. Here we tested the importance of reproductive seasonality for 26 populations representing 15 species living in multimale groups. We obtained data from the literature on paternity, number of males per group, receptive synchrony, and three measures of seasonality of reproduction. We analyzed these data using bivariate regressions and hierarchical regression by sets and controlled for the effect of evolutionary relationships using phylogenetic generalized least squares. As expected, alpha male paternity decreased as the number of males per group increased as well as with increasing female receptive synchrony. Reproductive seasonality did not explain variation in reproductive skew over and above the variation explained by synchrony and the number of males. Reproductive seasonality alone only explained a small proportion of the variation in skew, and there was no strong association between reproductive seasonality and synchrony. The effects of receptive synchrony and reproductive seasonality as well as their link were reduced if we excluded captive populations. These results indicate that across primates male reproductive skew is related to the number of competitors in a group and that seasonality does not reliably predict synchrony or male reproductive skew. 相似文献
768.
769.
770.
The local scale dispersion tensor, Dd, is a controlling parameter for the dilution of concentrations in a solute plume that is displaced by groundwater flow in a heterogeneous aquifer. In this paper, we estimate the local scale dispersion from time series or breakthrough curves, BTCs, of Br concentrations that were measured at several points in a fluvial aquifer during a natural gradient tracer test at Krauthausen. Locally measured BTCs were characterized by equivalent convection dispersion parameters: equivalent velocity, v(eq)(x) and expected equivalent dispersivity, [lambda(eq)(x)]. A Lagrangian framework was used to approximately predict these equivalent parameters in terms of the spatial covariance of log(e) transformed conductivity and the local scale dispersion coefficient. The approximate Lagrangian theory illustrates that [lambda(eq)(x)] increases with increasing travel distance and is much larger than the local scale dispersivity, lambda(d). A sensitivity analysis indicates that [lambda(eq)(x)] is predominantly determined by the transverse component of the local scale dispersion and by the correlation scale of the hydraulic conductivity in the transverse to flow direction whereas it is relatively insensitive to the longitudinal component of the local scale dispersion. By comparing predicted [lambda(eq)(x)] for a range of Dd values with [lambda(eq)(x)] obtained from locally measured BTCs, the transverse component of Dd, DdT, was estimated. The estimated transverse local scale dispersivity, lambda(dT) = DdT/U1 (U1 = mean advection velocity) is in the order of 10(1)-10(2) mm, which is relatively large but realistic for the fluvial gravel sediments at Krauthausen. 相似文献