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21.
This article sets out to analyse how and to what degree land use is linked to the physical characteristics of the territory itself, and the way in which changes in land use are determined by agricultural and socio-demographic dynamics. The study was conducted within the territorial boundaries of five municipalities surrounding Lake Trasimeno and refers to the periods 1977–2000 for land use and 1971–2001 for socio-demography data. The use of environmental, social, economic and agricultural indicators demonstrates how a mix of various indicators are useful for monitoring the changes which took place. It also shows the powerful influence that socio-demographic factors exert upon land use and landscape change.  相似文献   
22.
Every year, the number of discarded electro-electronic products is increasing. For this reason recycling is needed, to avoid wasting non-renewable natural resources. The objective of this work is to study the recycling of materials from parallel wire cable through unit operations of mineral processing. Parallel wire cables are basically composed of polymer and copper. The following unit operations were tested: grinding, size classification, dense medium separation, electrostatic separation, scrubbing, panning, and elutriation. It was observed that the operations used obtained copper and PVC concentrates with a low degree of cross contamination. It was concluded that total liberation of the materials was accomplished after grinding to less than 3 mm, using a cage mill. Separation using panning and elutriation presented the best results in terms of recovery and cross contamination.  相似文献   
23.
The impact of air traffic on the global atmosphere is characterised by a high degree of uncertainty, concerning both the physico-chemical phenomena involved and the extent of the forcing due to anthropogenic emissions. The different effects of these emissions (e.g. on climate change, stratospheric ozone depletion, acidification, tropospheric ozone formation) are dealt with by different international bodies and conventions (e.g. IPCC, EMEP. . .) which are trying to define a standard methodology allowing countries to evaluate their contributions to global aircraft emissions and to report these figures in a standardised way. The paper compares different methodologies proposed by the joint EMEP/CORINAIR 'Atmospheric Emission Inventory Guidebook' for estimating aircraft emissions. Adjustments to these methodologies have been proposed, in order to integrate some additional data such as the total amount of flight hours per aircraft type or fuel consumption per trip. In case detailed information is not available, we recommend the use of a VERY SIMPLE methodology which may yield acceptable results, provided that every country makes adequate assumptions on the average aircraft type.  相似文献   
24.
The biodegradation behavior of insoluble crystalline polymers depends on both chemical structure and physical state. The physical state is strongly affected by the molding conditions; moreover the presence of natural hydrophylic substances such as starch can further influence the biodegradation process. This paper examines the biotic and abiotic degradation of thick injection-molded parts, made of pure poly--caprolactone (PCL) at different molecular weights, and of PCL in the presence of starch in the case of a commercial grade of Mater-Bi, produced by Novamont. The abiotic degradation was studied at 25 and 50°C, whereas the biotic degradation was followed in conditions of SCAS (semicontinuous activated sludges) at 25 and 50°C, soil burial, and controlled composting. The physical-chemical modifications provoked at the surface and in the bulk of the samples by the different types of degradation were determined by differential scanning calorimetry, viscometric and gravimetric analysis, scanning electron microscopy, and dynamic mechanical analysis. The mechanical modifications induced by the different environments were followed by tensile tests. It was demonstrated that the presence of starch significantly increases the apparent biodegradation rate of PCL, making even thick parts of ZI01U compatible with the composting process.Paper presented at the Bio/Environmentally Degradable Polymer Society—Third National Meeting, June 6–8, 1994, Boston, Massachusetts.  相似文献   
25.
Mothers may profoundly affect offspring phenotype and performance by adjusting egg components, including steroid hormones. We studied the effects of elevated prenatal testosterone (T) exposure in the ring-necked pheasant on the expression of a suite of male and female traits, including perinatal response to stress, immune response, growth, and secondary sexual traits. Prenatal T levels were increased by injecting the yolk of unincubated eggs with physiological doses of the hormone. Yolk T injection resulted in a reduced length of male tarsal spurs, a trait which positively predicts male success in intra- and intersexual selection and viability, whereas no direct effect on male wattle characteristics or plumage traits of either sex was observed. Female spur length was also negatively affected by T, but to a lesser extent than in males. In addition, the covariation between male secondary sexual traits, which are reliable quality indicators, differed between T and control males, suggesting that the manipulation may have altered the assessment of overall male quality by other males and females. In conclusion, the negative effects of elevated yolk T on spur length, a trait which positively predicts male fitness, coupled with the lack of effects on growth or other traits in both sexes, provided limited evidence for mothers being subjected to a trade-off between positive and negative consequences of yolk T deposition on offspring traits and suggest that directional selection for reduced yolk T levels may occur in the ring-necked pheasant.  相似文献   
26.
Feral swine were targeted for control at Avon Park Air Force Range in south-central Florida to avert damage to sensitive wetland habitats on the 40,000-ha base. We conducted a 5-year study to assess impacts from control to this population that had been recreationally hunted for many years. Control was initiated in early 2009. The feral swine population was monitored from 2008 to 2012 using a passive tracking index (PTI) during the dry and wet seasons and using recreational hunter take rates from the dry season. All three indices showed substantial feral swine declines after implementing control, with indices leveling for the final two study years. Military missions and recreational hunting seasons impacted temporal and spatial consistency of control application, thereby limiting further impacts of control efforts on the feral swine population. The PTI was also able to monitor coyotes, another invasive species on the base, and detect Florida black bear and Florida panther, species of particular concern.  相似文献   
27.
28.
The length ratio between individual digits differs between males and females in humans, other mammals, lizards, and one bird species. Sexual dimorphism in digit ratios and variation among individuals of the same sex may depend on differential exposure to androgens and estrogens during embryonic life. Organizational effects of sex hormones could cause the observed correlations between digit ratios and diverse phenotypic traits in humans. However, no study has investigated experimentally the effect of prenatal estrogens on digit ratios. We analyzed the effect of estradiol injection in ring-necked pheasant (Phasianus colchicus) eggs on digit ratios. Males from control eggs had higher ratios between the second or third and the fourth digit of the right foot compared to females. Estradiol-treated eggs produced males with lower (feminized) right foot second to fourth digit ratio. Thus, we provided the first experimental evidence that prenatal exposure to physiologically high estrogen levels affects bird digit ratios.  相似文献   
29.
IntroductionData availability has forced researchers to examine separately the role of alcohol among drivers who crashed and drivers who did not crash. Such a separation fails to account fully for the transition from impaired driving to an alcohol-related crash.MethodIn this study, we analyzed recent data to investigate how traffic-related environments, conditions, and drivers’ demographics shape the likelihood of a driver being either involved in a crash (alcohol impaired or not) or not involved in a crash (alcohol impaired or not). Our data, from a recent case–control study, included a comprehensive sampling of the drivers in nonfatal crashes and a matched set of comparison drivers in two U.S. locations. Multinomial logistic regression was applied to investigate the likelihood that a driver would crash or would not crash, either with a blood alcohol concentration (BAC) = .00 or with a BAC  .05.ConclusionsTo our knowledge, this study is the first to examine how different driver characteristics and environmental factors simultaneously contribute to alcohol use by crash-involved and non-crash-involved drivers. This effort calls attention to the need for research on the simultaneous roles played by all the factors that may contribute to motor vehicle crashes.  相似文献   
30.
Chlorpyrifos is an anticholinesterase organophosphate insecticide widely used in Argentina in the production of food derived from animal, fruit and horticultural origin and is reported as a residue within these products. Local reference values for acetyl and butyrylcholinesterase were determined in Aberdeen Angus bovine and cross bred cattle (n = 25), a requirement to be able to evaluate toxicity of commercial organophosphate and carbamate formulations. The activity of cholinesterase enzymes presented an overall mean of 2,183.00 ± 485.6 IU L?1 for erythrocyte acetylcholinesterase and 203.1 ± 42.06 IU L?1 for plasma butyrylcholinesterase, which are used as reference values for meat steers within a system of intensive production in a semi-arid region. The toxic potential of chlorpyrifos in steers of the same breeds (n = 12) was assessed applying chlorpyrifos 15.00% Tipertox® in a single therapeutic dose of 7.50 mg kg?1 by topical route. Prior to application and then on day 1 and day 21 post-application, both blood cholinesterases, serum chlorpyrifos concentration by ultra-high resolution liquid chromatography with mass detector, analysis of blood counts, total proteins, liver enzymes, urea and creatinine were evaluated. The mean plasma concentration of chlorpyrifos was 27.90 ug L?1 at 24 h. The findings indicate that the therapeutic treatment of castrated male bovines treated with chlorpyrifos, applied by pour-on according to the manufacturer's instructions, does not cause changes in the variables evaluated.  相似文献   
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