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981.
In the indoor environment, settled surface dust often functions as a reservoir of hazardous particulate contaminants. In many
circumstances, a major contributing source to the dust pool is exterior soil. Young children are particularly susceptible
to exposure to both outdoor derived soil and indoor derived dust present in the indoor dust pool. This is because early in
life the exploratory activities of the infant are dominated by touching and mouthing behavior. Inadvertent exposure to dust
through mouth contact and hand-to-mouth activity is an inevitable consequence of infant development. Clean-up of indoor dust
is, in many circumstances, critically important in efforts to minimize pediatric exposure. In this study, we examine the efficiency
of vacuum cleaner removal of footwear-deposited soil on vinyl floor tiles. The study utilized a 5 × 10 foot (c. 152.5 × 305 cm)
test surface composed of 1-foot-square (c. 30.5 × 30.5 cm) vinyl floor tiles. A composite test soil with moderately elevated
levels of certain elements (e.g., Pb) was repeatedly introduced onto the floor surface by footwear track-on. The deposited
soil was subsequently periodically removed from randomly selected tiles using a domestic vacuum cleaner. The mass and loading
of soil elements on the tiles following vacuuming were determined both by wet wipe collection and by subsequent chemical analysis.
It was found that vacuum cleaner removal eliminated much of the soil mass from the floor tiles. However, a small percentage
of the mass was not removed and a portion of this residual mass could be picked up by moistened hand-lifts. Furthermore, although
the post-vacuuming tile soil mass was sizably reduced, for some elements (notably Pb) the concentration in the residual soil
was increased. We interpret this increased metal concentration to be a particle size effect with smaller particles (with a
proportionately higher metal content) remaining in situ after vacuuming. 相似文献
982.
Behavioural research on domestic pigs has included parent–offspring conflict, sibling competition, and the use of signals
which influence resource allocation. In this paper, we review key sow–piglet behavioural studies and discuss their relevance
to resource allocation theory. Sibling competition begins in the uterus and continues after birth, as piglets compete directly
for access to the sow’s teats. This competition is made more severe by a unique dentition, which newborn piglets use to lacerate
the faces of siblings during teat disputes. Competition often leads to the death of some littermates, especially those of
low birth weight. Piglets also compete indirectly for milk, apparently by stimulating milk production at the teats that they
habitually use at the expense of milk production by other teats. The complex nursing behavior of the sow appears designed
to prevent the more vigorous piglets from monopolizing the milk. Sows give vocal signals which both attract piglets to suckle
and synchronize their behavior during nursing episodes. Piglets give loud vocal signals when separated from the sow; calls
which vary in intensity and appear to be honest signals of need. Udder massage by piglets may also serve as an honest signal
of need. Parent–offspring conflict has been demonstrated experimentally in pigs. Specifically, when given the opportunity
to control contact with their piglets, sows nurse less frequently, provide less milk, and lose less weight during lactation
than sows that cannot control their level of contact. Because of this interesting natural history and because they are so
amenable to experimentation, domestic pigs provide a rich system for testing ideas drawn from resource allocation theory.
This contribution is part of the special issue “Sibling competition and cooperation in mammals” (guest editors: Robyn Hudson
and Fritz Trillmich). 相似文献
983.
The aim of this paper is to tackle the problem that arises from asymmetrical data cubes formed by two crossed factors fixed by the experimenter (factor A and factor B, e.g., sites and dates) and a factor which is not controlled for (the species). The entries of this cube are densities in species. We approach this kind of data by the comparison of patterns, that is to say by analyzing first the effect of factor B on the species-factor A pattern, and second the effect of factor A on the species-factor B pattern. The analysis of patterns instead of individual responses requires a correspondence analysis. We use a method we call Foucart's correspondence analysis to coordinate the correspondence analyses of several independent matrices of species x factor A (respectively B) type, corresponding to each modality of factor B (respectively A). Such coordination makes it possible to evaluate the effect of factor B (respectively A) on the species-factor A (respectively B) pattern. The results obtained by such a procedure are much more insightful than those resulting from a classical single correspondence analysis applied to the global matrix that is obtained by simply unrolling the data cube, juxtaposing for example the individual species x factor A matrices through modalities of factor B. This is because a single global correspondence analysis combines three effects of factors in a way that cannot be determined from factorial maps (factor A, factor B, and factor A x factor B interaction) whereas the applications of Foucart's correspondence analysis clearly discriminate two different issues. Using two data sets, we illustrate that this technique proves to be particularly powerful in the analyses of ecological convergence which include several distinct data sets and in the analyses of spatiotemporal variations of species distributions. 相似文献
984.
Hawkins BA Montoya D Rodríguez MA Olalla-Tárraga MA Zavala MA 《Ecology》2007,88(1):255-9; discussion 259-62
985.
The study of sexual segregation has received increasing attention over the last two decades. Several hypotheses have been proposed to explain the existence of sexual segregation, such as the "predation risk hypothesis," the "forage selection hypothesis," and the "activity budget hypothesis." Testing which hypothesis drives sexual segregation is hampered, however, by the lack of consensus regarding a formal measurement of sexual segregation. By using a derivation of the well-known chi-square (here called the sexual segregation and aggregation statistic [SSAS]) instead of existent segregation coefficients, we offer a reliable way to test for temporal variation in the occurrence of sexual segregation and aggregation, even in cases where a large proportion of animals are observed alone. A randomization procedure provides a test for the null hypothesis of independence of the distributions of males and females among the groups. The usefulness of SSAS in the study of sexual segregation is demonstrated with three case studies on ungulate populations belonging to species with contrasting life histories and annual grouping patterns (isard, red deer, and roe deer). The existent segregation coefficients were unreliable since, for a given value, sexual segregation could or could not occur. Similarly, the existent segregation coefficients performed badly when males and females aggregated. The new SSAS was not prone to such limitations and allowed clear conclusions regarding whether males and females segregate, aggregate, or simply mix at random applicable to all species. 相似文献
986.
Sven-Erik Gryning Ekaterina Batchvarova Daniel Schneiter Pierre Bessemoulin Heinz Berger 《Atmospheric environment (Oxford, England : 1994)》1998,32(24):993
The state of the boundary layer at the release site during the two tracer experiments is described, based on measurements of atmospheric turbulence carried out by a sonic anemometer, profiles of horizontal and vertical wind by a SODAR as well as frequent radiosonde releases. The boundary layer height is derived from radiosoundings, modelled and discussed. The study is meant as background for discussions of the tracer behaviour near the release site, and possible influence of the local meteorology at the release site on the long-range dispersion. The difference in the initial meso-meteorological conditions between the two experiments is discussed and some of its consequences for the dispersion of the released tracer are clarified. It is concluded that the first experiment is well suited for validation of long-range transport and dispersion models, whereas the second experiment calls for further model development. It is concluded that the micrometeorological measurements are very important as background information for the understanding of plume behaviour on small as well as long scales. 相似文献
987.
In recent years, many political parties have created new forms of affiliation and have justified the blurring of membership boundaries with claims that sympathisers would be more representative of the electorate and less radical. Such claims are based on ‘popular wisdom’ inspired by John May’s ‘special law of curvilinearity’, which states that activists hold more extreme views than voters and elites. When this expectation has been tested, results have been at best inconclusive; but testing has so far never used a single survey to compare different groups. Using an online survey of Europe Ecologie Les Verts party members and their extended networks (affiliated supporters, lapsed members, sympathisers), relationships between ideological differences and degree of investment in party activities and decision-making are analysed. The results, contradicting May’s special law along all ideological dimensions other than intra-party democracy, can be explained if May’s narrowly instrumental assumptions about preference formation are rejected. 相似文献
988.
Kiley Daley Rob Jamieson Daniel Rainham Lisbeth Truelstrup Hansen 《Environmental science and pollution research international》2018,25(33):32860-32872
Wastewater management in Canadian Arctic communities is influenced by several geographical factors including climate, remoteness, population size, and local food-harvesting practices. Most communities use trucked collection services and basic treatment systems, which are capable of only low-level pathogen removal. These systems are typically reliant solely on natural environmental processes for treatment and make use of existing lagoons, wetlands, and bays. They are operated in a manner such that partially treated wastewater still containing potentially hazardous microorganisms is released into the terrestrial and aquatic environment at random times. Northern communities rely heavily on their local surroundings as a source of food, drinking water, and recreation, thus creating the possibility of human exposure to wastewater effluent. Human exposure to microbial hazards present in municipal wastewater can lead to acute gastrointestinal illness or more severe disease. Although estimating the actual disease burdens associated with wastewater exposures in Arctic communities is challenging, waterborne- and sanitation-related illness is believed to be comparatively higher than in other parts of Canada. This review offers a conceptual framework and evaluation of current knowledge to enable the first microbial risk assessment of exposure scenarios associated with food-harvesting and recreational activities in Arctic communities, where simplified wastewater systems are being operated. 相似文献
989.
Shen Zhengtao Zhang Yunhui Jin Fei Alessi Daniel S. Zhang Yiyun Wang Fei McMillan Oliver Al-Tabbaa Abir 《Environmental science and pollution research international》2018,25(15):14626-14635
Environmental Science and Pollution Research - In order to understand the influence of feedstock type on biochar adsorption of heavy metals, the adsorption characteristics of nickel (Ni2+), copper... 相似文献
990.
Erica Souto Abreu Lima Talita de Santana Matos Helena Saraiva Koenow Pinheiro Leonardo Durval Duarte Guimarães Daniel Vidal Pérez Nelson Moura Brasil do Amaral Sobrinho 《Environmental monitoring and assessment》2018,190(6):364
The increasing concern regarding the preservation of soil quality suggests the adoption of quality reference values as a first step in environmental monitoring actions. In this context, the objective of this study was to establish soil quality reference values for Al, Zn, Mn, Cd, Fe, Pb, Ni, Cr, and Cu and to correlate several soil properties with the occurrence of these elements in the hillslope region of Rio de Janeiro State. Sixty-two samples were collected at depths of 0–20 and 20–40 cm and analyzed using the USEPA method 3051A. After clustering analysis, the samples were separated into three groups. Classification functions were obtained based on the variables pH - Mg - Fe - Mn, i.e., the variables that were best related to heavy metal content. We determined to establish the quality reference values for the 75th percentile of the three groups. The relief forms of the area, which facilitate the transport of soil fine-particle fractions and accumulation in lowlands, were revealed to be one of most important factors in understanding the distribution of soil heavy metals. 相似文献