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231.
Jolyon J. Faria John R. G. Dyer Romain O. Clément Iain D. Couzin Natalie Holt Ashley J. W. Ward Dean Waters Jens Krause 《Behavioral ecology and sociobiology》2010,64(8):1211-1218
Collective animal behaviour has attracted much attention recently, but cause-and-effect within interaction sequences has often
been difficult to establish. To tackle this problem, we constructed a robotic fish (‘Robofish’) with which three-spined sticklebacks
(Gasterosteus aculeatus L.) interact. Robofish is a computer-controlled replica stickleback that can be programmed to move around a tank. First,
we demonstrated the functioning of the method: that the sticklebacks interacted with Robofish. We examined two types of interaction:
recruitment and leadership. We found that Robofish could recruit a single fish from a refuge and could initiate a turn in
singletons and in groups of ten, i.e. act as a leader. We also showed that the influence of Robofish diminished after the
first 30 min that fish spent in a new environment. Second, using this method, we investigated the effects of metric and topological
inter-individual distance on the influence that Robofish had on the orientation of fish in a shoal of ten. We found that inter-individual
interactions during this turn were predominantly mediated by topological, rather than metric, distance. Finally, we discussed
the potential of this novel method and the importance of our findings for the study of collective animal behaviour. 相似文献
232.
This paper uses an integrated economic-environmental model to assess the point source pollution from major industries in Jefferson County, Northern Alabama. Industrial expansion generates employment, income, and tax revenue for the public sector; however, it is also often associated with the discharge of chemical pollutants. Jefferson County is one of the largest industrial counties in Alabama that experienced smog warnings and ambient ozone concentration, 1996-1999. Past studies of chemical discharge from industries have used models to assess the pollution impact of individual plants. This study, however, uses an extended Input-Output (I-O) economic model with pollution emission coefficients to assess direct and indirect pollutant emission for several major industries in Jefferson County. The major findings of the study are: (a) the principal emission by the selected industries are volatile organic compounds (VOC) and these contribute to the ambient ozone concentration; (b) the direct and indirect emissions are significantly higher than the direct emission by some industries, indicating that an isolated analysis will underestimate the emission by an industry; (c) while low emission coefficient industries may suggest industry choice they may also emit the most hazardous chemicals. This study is limited by the assumptions made, and the data availability, however it provides a useful analytical tool for direct and cumulative emission estimation and generates insights on the complexity in choice of industries. 相似文献
233.
The National Phosphorus Project rainfall simulator was used to quantify overland flow and P transport from nine sites distributed throughout the watershed of a New York City Watershed Agriculture Program collaborating dairy farm. Observed concentrations of total dissolved phosphorus (TDP) were low (0.007-0.12 mg L(-1)) in flow from deciduous forest, extensively managed pasture, and hillside seeps; moderate (0.18-0.64 mg L(-1)) in flow from intensively managed pastures, a hayfield, and a cow path; and extremely high (11.6 mg L(-1)) in flow from a manured barnyard. Concentrations of TDP from sites without fresh manure were strongly correlated with soil test P (TDP [mg L(-1)] = 0.0056 + 0.0180 x Morgan's soil test phosphorus [STP, mg kg(-1)]; R2 = 84%). Observed concentrations of suspended solids were low (16-137 mg L(-1)) in flow from vegetated sites, but were higher (375-615 mg L(-1)) in flow from sites with little ground cover (barnyard, cow path, plowed field). Under dry summer conditions the time to observed overland flow was shorter (<18 min) for nonfield areas (seeps, barnyard, cow path) than for field and forest areas (27-93 min), indicating that hydrologically active nonfield areas of minor spatial extent but with high soil P (e.g., cow paths and barnyards) can play a significant role in summertime P loading. When soils started from field capacity (second-day) time to overland flow was uniformly less than 23 min, indicating that under wet watershed conditions low-P source areas can dilute overland flow from concentrated sources. 相似文献
234.
Female control of reproductive skew in cooperatively breeding brown jays (<Emphasis Type="Italic">Cyanocorax morio</Emphasis>) 总被引:2,自引:0,他引:2
Brown jays (Cyanocorax morio) are long-lived, social corvids that live in large, stable, territorial groups (mean = 10 individuals). In this study, I determined the distribution of reproductive success within groups using multi-locus DNA fingerprinting. Breeding females produced virtually all (99%) of the young within their own nests. Reproduction within groups was highly skewed towards a single primary female, although long term data indicate that secondary females (female breeders that were usually younger and subordinate to the primary female) were sometimes successful. The high reproductive skew observed for females was associated with primary female aggression. Successful reproduction by secondary females may have been due to parental facilitation or the inability of primary females to completely suppress secondary females. Multiple paternity occurred in 31–43% of broods and extra-group paternity occurred in a minimum of 22% of broods. Patterns of paternity also varied between years, since females often switched or included new genetic mates. Although male consorts of nesting females fathered relatively few offspring (20%), they still had a higher chance of fathering offspring than any other single group male. Reproduction was less skewed for males than females as a result of female mating patterns. Female reproductive patterns are consistent with some of the predictions and assumptions from optimal skew models, while male reproductive patterns are not. The factors affecting skew in species with complex social systems such as incomplete control by breeders over subordinate reproduction, female control of paternity, and resource inheritance have not been well incorporated into reproductive skew models.Communicated by: J. Dickinson 相似文献
235.
Beauchemin S Hesterberg D Chou J Beauchemin M Simard RR Sayers DE 《Journal of environmental quality》2003,32(5):1809-1819
Knowledge of phosphorus (P) species in P-rich soils is useful for assessing P mobility and potential transfer to ground water and surface waters. Soil P was studied using synchrotron X-ray absorption near-edge structure (XANES) spectroscopy (a nondestructive chemical-speciation technique) and sequential chemical fractionation. The objective was to determine the chemical speciation of P in long-term-fertilized, P-rich soils differing in pH, clay, and organic matter contents. Samples of three slightly acidic (pH 5.5-6.2) and two slightly alkaline (pH 7.4-7.6) soils were collected from A or B horizons in two distinct agrosystems in the province of Québec, Canada. The soils contained between 800 and 2100 mg total P kg(-1). Distinct XANES features for Ca-phosphate mineral standards and for standards of adsorbed phosphate made it possible to differentiate these forms of P in the soil samples. The XANES results indicated that phosphate adsorbed on Fe- or Al-oxide minerals was present in all soils, with a higher proportion in acidic than in slightly alkaline samples. Calcium phosphate also occurred in all soils, regardless of pH. In agreement with chemical fractionation results, XANES data showed that Ca-phosphates were the dominant P forms in one acidic (pH 5.5) and in the two slightly alkaline (pH 7.4-7.6) soil samples. X-ray absorption near-edge structure spectroscopy directly identified certain forms of soil P, while chemical fractionation provided indirect supporting data and gave insights on additional forms of P such as organic pools that were not accounted for by the XANES analyses. 相似文献
236.
Lime stabilization of primary sludges 总被引:1,自引:0,他引:1
J B Farrell J E Smith S W Hathaway R B Dean 《Journal - Water Pollution Control Federation》1974,46(1):113-122
237.
Dean F. Martin Patricia M. Dooris George M. Dooris Robert J. Bova 《Journal of the American Water Resources Association》1986,22(2):283-287
ABSTRACT: High performance liquid chromatography (HPLC) has been used to identify a fraction of aqueous sediment extract from Lake Starvation, Hillsborough County, Florida, that is responsible for inhibition of hydrilla growth. The fraction was separated on a Zorbax? C18 preparative-scale column. The present study examines various lake sediment extracts and river water samples to determine the presence or absence of the inhibitor peak. The biologically active component is absent in certain rivers where hydrilla is prominent, but it is present in extracts of Lake Starvation and White Trout Lake sediments that are known to have hydrilla growth inhibiting properties. The implications of “fingerprinting” natural waters for hydrilla inhibitor through liquid chromatography are considered. 相似文献
238.
Dean O. Cliver 《Food and environmental virology》2009,1(1):3-9
Viruses are often transmitted via food and the environment. Contamination may be controlled either by preventing its occurrence
or by inactivating the contaminating virus. The majority of agents transmitted in this way are human enteric viruses, produced
either in the intestines or the liver. They are shed in human feces (noroviruses also in vomitus) in a broad range of circumstances,
and they are relatively stable outside the host. Non-enteric viruses are less often transmitted via foods and are generally
less environmentally stable. Insofar as vaccines are available, they are able to prevent fecal shedding. Viruses shed in feces
via the water-carriage toilet may be eliminated by proper treatment and disinfection of the wastewater. In the foods context,
the most effective antiviral measures are cooking and hand washing. Detection methods are most useful after the fact, in investigating
outbreaks and devising preventive measures. 相似文献
239.
Contributions of biofilm and suspended sludge to nitrogen transformation and
nitrous oxide emission in hybrid sequencing batch system 总被引:2,自引:0,他引:2
Ingwei Wayne Lo Kwang Victor Lo Don S Mavini Dean Shiskowski William Ramey 《环境科学学报(英文版)》2010,22(7):953-960
Hybrid system combines the nature of suspended growth and attached growth has been widely applied to wastewater treatment.
In this research, the contributions to N transformation and N2O emission by biofilm and suspended sludge in the hybrid sequencingbatch
reactor for a simultaneous nitrification, denitrification and phosphorus removal process were investigated. For the hybrid system,
nitrification occurred mostly in the suspended sludge, while the biofilm played the major role in denitrification. The interaction of
the biofilm and the suspended sludge in the same reactor resulted in a better overall nitrogen removal performance with simultaneous
nitrification and denitrification. However, N2O emission was the main end product of nitrogen removal for the hybrid system; while
it was N2 for the biofilm. The relative low N2O emissions from the pure biofilm and the pure suspended sludge corresponded to the
relatively high nitrate at the end of the aeration period compared with the hybrid system. 相似文献
240.
Estimation of daily intake of potentially toxic elements from urban street dust and the role of oral bioaccessibility testing 总被引:2,自引:0,他引:2
The pseudo-total and oral bioaccessible concentration of six potentially toxic elements (PTEs) in urban street dust was investigated. Typical pseudo-total concentrations across the sampling sites ranged from 4.4 to 8.6 mg kg−1 for As, 0.2-3.6 mg kg−1 for Cd, 25-217 mg kg−1 for Cu, 14-46 mg kg−1 for Ni, 70-4261 mg kg−1 for Pb, and, 111-652 mg kg−1 for Zn. This data compared favourably with other urban street dust samples collected and analysed in a variety of cities globally; the exception was the high level of Pb determined in a specific sample in this study. The oral bioaccessibility of PTEs in street dust is also assessed using in vitro gastrointestinal extraction (Unified Bioaccessibility Method, UBM). Based on a worst case scenario the oral bioaccessibility data estimated that Cd and Zn had the highest % bioaccessible fractions (median >45%) while the other PTEs i.e. As, Cu, Ni and Pb had lower % bioaccessible fractions (median <35%). The pseudo-total and bioaccessible concentrations of PTEs in the samples has been compared to estimated tolerable daily intake values based on unintentional soil/dust consumption. Cadmium, Cu and Ni are well within the oral tolerable daily intake rates. With respect to As and Pb, only the latter exceeds the TDIoral if we model ingestion rate based on atmospheric ‘dustiness’ rather than the US EPA (2008) unintentional soil/dust consumption rate of 100 mg d−1. We consider it unlikely that even a child with pica tendencies would ingest as much as 100 mg soil/dust during a daily visit to the city centre, and in particular to the sites with elevated Pb concentrations observed in this study. 相似文献