949 resultados para U.S. Fish and Wildlife Service. Division of Law Enforcement
Resumo:
A census of 925 U.S. colleges and universities offering masters and doctorate degrees was conducted in order to study the number of elements of an environmental management system as defined by ISO 14001 possessed by small, medium and large institutions. A 30% response rate was received with 273 responses included in the final data analysis. Overall, the number of ISO 14001 elements implemented among the 273 institutions ranged from 0 to 16, with a median of 12. There was no significant association between the number of elements implemented among institutions and the size of the institution (p = 0.18; Kruskal-Wallis test) or among USEPA regions (p = 0.12; Kruskal-Wallis test). The proportion of U.S. colleges and universities that reported having implemented a structured, comprehensive environmental management system, defined by answering yes to all 16 elements, was 10% (95% C.I. 6.6%–14.1%); however 38% (95% C.I. 32.0%–43.8%) reported that they had implemented a structured, comprehensive environmental management system, while 30.0% (95% C.I. 24.7%–35.9%) are planning to implement a comprehensive environmental management system within the next five years. Stratified analyses were performed by institution size, Carnegie Classification and job title. ^ The Osnabruck model, and another under development by the South Carolina Sustainable Universities Initiative, are the only two environmental management system models that have been proposed specifically for colleges and universities, although several guides are now available. The Environmental Management System Implementation Model for U.S. Colleges and Universities developed is an adaptation of the ISO 14001 standard and USEPA recommendations and has been tailored to U.S. colleges and universities for use in streamlining the implementation process. In using this implementation model created for the U.S. research and academic setting, it is hoped that these highly specialized institutions will be provided with a clearer and more cost-effective path towards the implementation of an EMS and greater compliance with local, state and federal environmental legislation. ^
Resumo:
The general research question for this dissertation was: do the data on adolescent sexual experiences and sexual initiation support the explicit or implicit adolescent sexuality theories informing the sexual health interventions currently designed for youth? To respond to this inquiry, three different studies were conducted. The first study included a conceptual and historical analysis of the notion of adolescence introduced by Stanley Hall, the development of an alternative model based on a positive view of adolescent sexuality, and the rationale for introducing to adolescent sexual health prevention programs the new definitions of sexual health and the social determinants of health approach. The second one was a quantitative study aimed at surveying not only adolescents' risky sexual behaviors but also sexual experiences associated with desire/pleasure which have been systematically neglected when investigating the sexual and reproductive health of the youth. This study was conducted with a representative sample of the adolescents attending public high schools in the State of Caldas in the Republic of Colombia. The third study was a qualitative analysis of 22 interviews conducted with male and female U.S. Latino adolescents on the reasons for having had or having not had vaginal sex. The more relevant results were: most current adolescent sexual health prevention programs are still framed in a negative approach to adolescent sexuality developed a century ago by Stanley Hall and Sigmund Freud which do not accept the adolescent sexual experience and propose its sublimation. In contrast, the Colombian study indicates that, although there are gender differences, adolescence is for males and females a normal period of sexual initiation not limited to coital activity, in which sexual desire/pleasure is strongly associated with sexual behavior. By the same token, the study about the reasons for having had or not had initiated heterosexual intercourse indicated that curiosity, sexual desire/pleasure, and love are basic motivations for deciding to have vaginal sexual intercourse for the first time and that during adolescence, young women and men reach the cognitive development necessary for taking conscious decisions about their sexual acts. The findings underline the importance of asking pertinent questions about desire/pleasure when studying adolescent sexuality and adopting an evidence-based approach to sexual health interventions.^
Resumo:
Hydrothermal circulation at oceanic spreading ridges causes sea water to penetrate to depths of 2 to 3 km in the oceanic crust where it is heated to ~400 °C before venting at spectacular 'black smokers'. These hydrothermal systems exert a strong influence on ocean chemistry (Edmond et al., 1979, doi:10.1016/0012-821X(79)90061-X), yet their structure, longevity and magnitude remain largely unresolved (Elderfield and Schultz., 1996, doi:10.1146/annurev.earth.24.1.191). The active Transatlantic Geotraverse (TAG) deposit, at 26° N on the Mid-Atlantic Ridge, is one of the largest, oldest and most intensively studied of the massive sulphide mounds that accumulate beneath black-smoker fields. Here we report ages of sulphides and anhydrites from the recently drilled (Humphris et al., 1995, doi:10.1038/377713a0) TAG substrate structures -determined from 234U-230Th systematics analysed by thermal ionization mass spectrometry. The new precise ages combined with existing data (Lalou et al., 1993, doi:10.1029/92JB01898; 1998, doi:10.2973/odp.proc.sr.158.214.1998) show that the oldest material (11,000 to 37,000 years old) forms a layer across the centre of the deposit with younger material (2,300-7,800 years old) both above and below. This stratigraphy confirms that much of the sulphide and anhydrite are precipitated within the mound by mixing of entrained sea water with hydrothermal fluid (James and Elderfield, 1996, doi:10.1130/0091-7613(1996)024<1147:COOFFA>2.3.CO;2). The age distribution is consistent with episodic activity of the hydrothermal system recurring at intervals of up to 2,000 years.
Resumo:
Marine birds are important predators in the marine ecosystem, and dietary studies can give useful information about their feeding ecology, food webs and oceanographic variability. The aim of this study was to increase our understanding of the diet and trophic level of the seabirds breeding in Kongsfjorden, Svalbard. We have used fatty acids and stable isotopes, both of which integrate diet information over space and time, to determine trophic relationships in marine food webs. Fatty acid compositions of muscle from Little auk (Alle alle), Brünnich's guillemot (Uria lomvia), Black-legged kittiwake (Rissa tridactyla), Northern fulmar (Fulmarus glacialis) and Glaucous gull (Larus hyperboreus) were determined and compared with their prey species. Canonical analysis (CA) showed that fatty acid composition differed among the five seabird species. Little auk, Black-legged kittiwake and Northern fulmar had high levels of the Calanus markers 20:1n9 and 22:1, indicating that these seabirds are a part of the Calanus food chain. Brünnich's guillemot differed from the other species with much lower levels of 20:1n9 and 22:1. Brünnich's guillemot is a pursuit diver feeding on fish and amphipods deeper in the water column, below 30 m. Glaucous gull also differed from the other seabird species, with a larger variation in the fatty acid composition indicating a more diverse diet. Trophic level analysis placed Little auk at the lowest trophic level, Brünnich's guillemot and Black-legged kittiwake at intermediate levels and Glaucous gull and Northern fulmar at the highest trophic level.
Resumo:
The Duolong porphyry Cu-Au deposit (5.4 Mt at 0.72% Cu, 41 t at 0.23 g/t Au), which is related to the granodiorite porphyry and the quartz-diorite porphyry from the Bangongco copper belt in central Tibet, formed in a continental arc setting. Here, we present the zircon U-Pb ages, geochemical whole-rock, Sr-Nd whole-rock and zircon in-situ Hf-O isotopic data for the Duolong porphyries. Secondary ion mass spectrometry (SIMS) zircon U-Pb analyses for six samples yielded consistent ages of ~118 Ma, indicating a Cretaceous formation age. The Duolong porphyries (SiO2 of 58.81-68.81 wt.%, K2O of 2.90-5.17 wt.%) belong to the high-K calc-alkaline series. They show light rare earth element (LREE)-enriched distribution patterns with (La/Yb)N = 6.1-11.7, enrichment in large ion lithophile elements (e.g., Cs, Rb, and Ba) and depletion of high field strength elements (e.g., Nb), with negative Ti anomalies. All zircons from the Duolong porphyries share relatively similar Hf-O isotopic compositions (d18O=5.88-7.27 per mil; eHf(t)=3.6-7.3), indicating that they crystallized from a series of cogenetic melts with various degrees of fractional crystallization. This, along with the general absence of older inherited zircons, rules out significant crustal contamination during zircon growth. The zircons are mostly enriched in d18O relative to mantle values, indicating the involvement of an 18O-enriched crustal source in the generation of the Duolong porphyries. Together with the presence of syn-mineralization basaltic andesite, the mixing between silicic melts derived from the lower crust and evolved H2O-rich mafic melts derived from the metsomatizied mantle wedge, followed by subsequent fractional crystallization (FC) and minor crustal contamination in the shallow crust, could well explain the petrogenesis of the Duolong porphyries. Significantly, the hybrid melts possibly inherited the arc magma characteristics of abundant F, Cl, Cu, and Au elements and high oxidation state, which contributed to the formation of the Duolong porphyry Cu-Au deposit.
Resumo:
High-resolution records of opal, carbonate, and terrigenous fluxes have been obtained from a high-sedimentation rate core (MD84-527: 43°50'S; 51°19'E; 3269 m) by normalization to 230Th. This method estimates paleofluxes to the seafloor on a point-by-point basis and distinguishes changes in sediment accumulation due to variations in vertical rain rates from those due to changes in syndepositional sediment redistribution by bottom currents. We also measured sediment delta15N to evaluate the changes in nitrate utilization in the overlying surface waters associated with paleoflux variations. Our results show that opal accumulation rates on the seafloor during the Holocene and stage 3, based on 14C dating, were respectively tenfold and fivefold higher than the vertical rain rates, At this particular location, changes in opal accumulation on the seafloor appear to be mainly controlled by sediment redistribution by bottom currents rather than variations in opal fluxes from the overlying water column. Correction for syndepositional sediment redistribution and the improved time resolution that can be achieved by normalization to 230Th disclose important variations in opal rain rates. We found relatively high but variable opal paleoflux during stage 3, with two maxima centered at 36 and 30 kyr B.P., low opal paleoflux during stage 2 and deglaciation and a pronounced maximum during the early Holocene, We interpret this record as reflecting variations in opal production rates associated with climate-induced latitudinal migration of the southern ocean frontal system. Sediments deposited during periods of high opal paleoflux also have high authigenic U concentrations, suggesting more reducing conditions in the sediment, and high Pa-231/Th-230 ratios, suggesting increased scavenging from the water column. Sediment delta15N is circa 1.5 per mil higher during isotopic stage 2 and deglaciation. The low opal rain rates recorded during that period appear to have been associated with increased nitrate depletion. This suggests that opal paleofluxes do not simply reflect latitudinal migration of the frontal system but also changes in the structure of the upper water column. Increased stratification during isotopic stage 2 and deglaciation could have been produced by a meltwater lid, leading to lower nitrate supply rates to surface waters.