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111.
Youth gambling has become an important public health issue in Canada and elsewhere owing to the known associations between
gambling and delinquency, family dysfunction and suicide. Modern electronic and virtual gambling activities like video lottery
terminals (VLTs) may have particular appeal to youth who have been raised in social environments that are increasingly dependent
on information and communication technologies. The main objective of the study was to explore why youth gamble and what makes
gambling activities like VLTs popular to youth in the places where youth live, study and play. The research is framed within
a population health perspective that recognizes the role of social and physical environments in influencing health-related
behaviours. Group discussions were conducted with youth to explore the popularity and appeal of gambling and VLTs, and how
gambling fits into the daily routines of youth and the spaces they occupy. Methodologically, this research was conscious of
responding to calls in the literature to analyze focus groups as an interactive group process rather a collection of individual
responses, and to exercise analytic rigour by explicitly making the research team’s positionality and the data collection
process transparent. Group discussions revealed gender differences in the appeal of particular gambling activities with young
males being more likely to discuss poker, dice, sports-betting and online gambling as exciting social activities, while females
described lottery and scratch (instant win) tickets as fun solitary activities. Substantive results point to the need for
interventions to address social aspects of gambling that appeal, in particular, to young males potentially through increased
provision of healthier alternatives to social engagement and greater attention to young people’s use of space. 相似文献
112.
Karen Rappé Nancy Fockedey Carl Van Colen Andre Cattrijsse Jan Mees Magda Vincx 《Estuarine, Coastal and Shelf Science》2011
The distribution and general population characteristics of five mysid shrimps were investigated in the period 2003–2005 in the Westerschelde estuary, a tidal temperate estuary situated along the Dutch–Belgian border. Multivariate analyses revealed that salinity predominantly governs the spatial distribution of Neomysis integer, Gastrosaccus spinifer, Schistomysis kervillei and Schistomysis spiritus while temperature, and to a lesser extent turbidity, control the distribution of Mesopodopsis slabberi. N. integer is a resident species in the mesohaline zone of the estuary, i.e. all life stages of the species are present in the estuary throughout the year. For the first time since decades N. integer inhabits the oligohaline zone of the estuary supposedly as a consequence of improved oxygen conditions in the upstream reaches. M. slabberi, the most abundant mysid in the Westerschelde, dominates the hyperbenthos of the mesohaline zone of the estuary. The polyhaline zone of the estuary is, most abundantly inhabited by M. slabberi, G. spinifer, S. kervillei and to a lesser extent by S. spiritus. The abundance of the latter four species is low in winter, probably due to a migration towards coastal waters to avoid colder temperatures in the estuary combined with an increased mortality after breeding. The sex ratio of all the mysid populations corresponds to the expected 1:1 female:male ratio and no salinity governed segregation is found between the different life stages of each mysid population. A seasonal variation exists in brood size in the N. integer population regardless of the body size, with a larger number of broods during winter and spring compared to the summer. In the other mysid populations the brood sizes vary only with the length of the ovigerous females. 相似文献
113.
Laura L. Brothers Joseph T. Kelley Daniel F. Belknap Walter A. Barnhardt Brian D. Andrews Melissa Landon Maynard 《Geo-Marine Letters》2011,31(4):237-248
Mechanisms and timescales responsible for pockmark formation and maintenance remain uncertain, especially in areas lacking
extensive thermogenic fluid deposits (e.g., previously glaciated estuaries). This study characterizes seafloor activity in
the Belfast Bay, Maine nearshore pockmark field using (1) three swath bathymetry datasets collected between 1999 and 2008,
complemented by analyses of shallow box-core samples for radionuclide activity and undrained shear strength, and (2) historical
bathymetric data (report and smooth sheets from 1872, 1947, 1948). In addition, because repeat swath bathymetry surveys are
an emerging data source, we present a selected literature review of recent studies using such datasets for seafloor change
analysis. This study is the first to apply the method to a pockmark field, and characterizes macro-scale (>5 m) evolution
of tens of square kilometers of highly irregular seafloor. Presence/absence analysis yielded no change in pockmark frequency
or distribution over a 9-year period (1999–2008). In that time pockmarks did not detectably enlarge, truncate, elongate, or
combine. Historical data indicate that pockmark chains already existed in the 19th century. Despite the lack of macroscopic
changes in the field, near-bed undrained shear-strength values of less than 7 kPa and scattered downcore 137Cs signatures indicate a highly disturbed setting. Integrating these findings with independent geophysical and geochemical
observations made in the pockmark field, it can be concluded that (1) large-scale sediment resuspension and dispersion related
to pockmark formation and failure do not occur frequently within this field, and (2) pockmarks can persevere in a dynamic
estuarine setting that exhibits minimal modern fluid venting. Although pockmarks are conventionally thought to be long-lived
features maintained by a combination of fluid venting and minimal sediment accumulation, this suggests that other mechanisms
may be equally active in maintaining such irregular seafloor morphology. One such mechanism could be upwelling within pockmarks
induced by near-bed currents. 相似文献
114.
Abstract Cloud‐motion winds measured from organized and disorganized cumulus cloud fields are compared with winds measured at collocated buoys in the northeast Pacific Ocean. Findings suggest that an automated tracking algorithm using GOES satellite imagery can measure cloud‐level winds at these latitudes. Comparisons with buoy wind measurements show that the influence of boundary‐layer stability should be included in estimates of surface winds from cloud‐motion data. 相似文献
115.
D. Rees T.J. Fuller-Rowell M.F. Smith R. Gordon T.L. Killeen P.B. Hays N.W. Spencer L. Wharton N.C. Maynard 《Planetary and Space Science》1985,33(4):425-456
One of the most consistent and often dramatic interactions between the high latitude ionosphere and the thermosphere occurs in the vicinity of the auroral oval in the afternoon and evening period. Ionospheric ions, convected sunward by the influence of the magnetospheric electric field, create a sunward jet-stream in the thermosphere, where wind speeds of up to 1 km s?1 can occur. This jet-stream is nearly always present in the middle and upper thermosphere (above 200 km altitude), even during periods of very low geomagnetic activity. However, the magnitude of the winds in the jet-stream, as well as its location and range in latitude, each depend on geomagnetic activity. On two occasions, jet-streams of extreme magnitude have been studied using simultaneous ground-based and satellite observations, probing both the latitudinal structure and the local time dependence. The observations have then been evaluated with the aid of simulations using a global, three-dimensional, time-dependent model of thermospheric dynamics including the effects of magnetospheric convection and particle precipitation. The extreme events, where sunward winds of above 800 ms?1 are generated at relatively low geomagnetic latitudes (60–70°) require a greatly expanded auroral oval and large cross-polar cap electric field ( ~ 150 kV). These in turn are generated by a persistent strong Interplanetary Magnetic Field, with a large southward component. Global indices such as Kp are a relatively poor indicator of the magnitude and extent of the jet-stream winds. 相似文献
116.
Nancy L. CHABOT Andrew J. CAMPBELL John H. JONES Munir HUMAYUN Carl B. AGEE 《Meteoritics & planetary science》2003,38(2):181-196
Abstract— Experimental solid metal‐liquid metal partition coefficients have been used to model the crystallization of magmatic iron meteorites and understand the evolution of asteroid cores. However, the majority of the partitioning experiments have been conducted with trace elements doped at levels that are orders of magnitude higher than measured in iron meteorites. Concern about Henry's Law and the unnatural doping levels have been cited as one reason that two recent iron meteorite studies have dismissed the experimental partition coefficients in their modeling. Using laser ablation ICP‐MS analysis, this study reports experimentally determined solid metal‐liquid metal trace element partition coefficients from runs doped down to the levels occurring in iron meteorites. The analyses for 12 trace elements (As, Co, Cr, Cu, Ga, Ge, Ir, Os, Pd, Pt, Re, and W) show no deviations from Henry's Law, and these results support decades of experimental work in which the partition coefficients were assumed to be independent of trace element concentration. Further, since our experiments are doped with natural levels of trace elements, the partitioning results are directly applicable to iron meteorites and should be used when modeling their crystallization. In contrast, our new Ag data are inconsistent with previous studies, suggesting the high Ag‐content in previous studies may have influenced the measured Ag partitioning behavior. 相似文献
117.
Processing U ores in the JEB Mill of the McClean Lake Operation in northern Saskatchewan produces spent leaching solutions (raffinates) with pH 1.5, and As and Ni concentrations up to 6800 and 5200 mg L−1, respectively. Bench-scale neutralization experiments (pH 2–8) were performed to help optimize the design of mill processes for reducing As and Ni concentrations in tailings and raffinates to 1 mg L−1 prior to their disposal. Precipitate mineralogy determined by chemical analysis, XRD, SEM, EM, XM and EXAFS methods, included gypsum (the dominant precipitate), poorly crystalline scorodite (precipitated esp. from pH 2–4), annabergite, hydrobasaluminite, ferrihydrite, green rust II and theophrastite. The As was mostly in scorodite with smaller amounts in annabergite and trace As adsorbed and/or co-precipitated, probably by ferrihydrite. Geochemical modeling indicated that above pH 2, the ion activity product (IAP) of scorodite lies between the solubility products of amorphous and crystalline phases (log Ksp = −23.0 and −25.83, respectively). The IAP decreases with increasing pH, suggesting that the crystallinity of the scorodite increases with pH. Forward geochemical models support the assumption that during neutralization, particles of added base produce sharp local pH gradients and disequilibrium with bulk solutions, facilitating annabergite and theophrastite precipitation. 相似文献
118.
Representative samples from the upper Cretaceous pyrometamorphic rocks from Suweileh area were investigated by using XRD, XRF, SEM/EDS, and microprobe techniques. Suweileh area is characterized by the presence of varicolored marble (dominated by green apatite-rich rocks) overlying bituminous marl and silicified limestone-phosphorite beds. The bituminous rocks are enriched with P, S, and F in addition to reduced sensitive trace elements that were inherited later by their metamorphic equivalents. The rocks were affected by severe tectonism that produced intensive fracturing which facilitated the chemical leaching. The mineralogy of the varicolored marble from Suweileh area is equivalent to Daba-Siwaqa and Maqarin areas in central and north Jordan. High-temperature and low-temperature groups of minerals were recognized. The first group is the result of pyrometamorphism produced from the spontaneous combustion of bituminous marl. The metamorphism was contemporaneous with tectonism of the Rift Valley. The second secondary group of minerals is the result of alteration by high alkaline waters followed by precipitation along the weakness zones. A hyperalkaline circulating water similar to the current issuing waters from Maqarin (north Jordan) was responsible for leaching and precipitation of anions and trace elements. A similar scenario was reported in north and central Jordan. The calculated structural formula of fluorapatite is Ca5.02 (P2.325, Si0.22, S0.0833) O12 F0.975. The apatite structure incorporates S and Si (inherited from the bituminous precursor) that substitute for P in the tetrahedral positions. 相似文献
119.
Nancy Chow Annette D. George Kate M. Trinajstic Zhong‐Qiang Chen 《Sedimentology》2013,60(7):1583-1620
Facies architecture and platform evolution of an early Frasnian reef complex in the northern Canning Basin of north‐western Australia were strongly controlled by syn‐depositional faulting during a phase of basin extension. The margin‐attached Hull platform developed on a fault block of Precambrian basement with accommodation largely generated by movement along the Mount Elma Fault Zone. Recognition of major subaerial exposure and flooding surfaces in the Hull platform (from outcrop and drillcore) has enabled comparison of facies associations within a temporal framework and led to identification of three stages of platform evolution. Stage 1 records initial ramp development on the hangingwall dip slope with predominantly deep subtidal conditions that prevented any cyclic facies arrangements. This stage is characterised by basal siliciclastic deposits and a major deepening‐upward facies pattern that is capped by a sequence boundary towards the footwall (north‐west) and a major flooding surface towards the hangingwall. Stage 2 reflects the bulk of platform aggradation, significant platform growth towards the hangingwall and the development of reef margins and cyclic facies arrangements. Thickening of this stage towards the hangingwall indicates that accommodation was generated by rotation of the fault block and overlying platform. Stage 3 records a major flooding and backstep of the platform margin. The Hull platform illustrates important elements of margin‐attached carbonate platforms in a half‐graben setting, including: (i) prominent, but limited, coarse siliciclastic input that does not have a major detrimental effect on carbonate production near the rift margin in arid to semi‐arid settings; (ii) wedge‐shaped accommodation created by syn‐depositional rotation of fault blocks and tilting of the hangingwall dip slope, resulting in shallow‐water facies and subaerial exposure up‐dip of the rotational axis and deeper water facies down‐dip; and (iii) evolution of a ramp to rimmed shelf, coincident with a sequence boundary–flooding surface, that is accelerated by tilting of the hangingwall dip slope during fault‐block rotation. 相似文献
120.
Sediment transport and short‐term morphologic change were evaluated at a site where sand fences are deployed and the beach is raked (Managed Site) and a site where these human adjustments are not practiced (Unmanaged Site). Data were gathered across the seaward portion of a low foredune when winds blew nearly shore‐normal at mean speeds 8.9 to 9.3 m s‐1. Data from traps revealed sediment transport rates at unvegetated portions of the foredune crest (40.2 to 43.5 kg m‐1 h‐1) were greater than on the backshore (4.9 to 11.2 kg m‐1 h‐1) due to onshore decreases in surface moisture and speed‐up of the wind passing over the foredune. Data from erosion pins indicate sediment input to the dune was 1.48 m3 m‐1 alongshore at the Managed Site and 1.25 m3 m‐1 at the Unmanaged Site. The Unmanaged Site had deposition at the dune toe, erosion at mid‐slope, and deposition at the crest. Deposition occurred at mid‐slope on the Managed Site near a partially buried (0.58 m high) fence with a porosity of about 65%. Deposition at partially buried wrack on the upper backshore and dune toe at the Unmanaged Site was about twice as great as deposition in this zone at the Managed Site. Results indicate that: (1) the seaward slope of the foredune can be a more important source of sand to the lee of the crest than the beach; (2) wrack near the toe can decrease transport into the foredune; (3) a scour zone can occur on the foredune slope above the wrack line; (4) a fence placed in this location can promote deposition and offset scour, but fences can restrict delivery of sediment farther inland. Evaluation of alternative configurations of fences and strategies for managing wrack is required to better determine the ways that humans modify foredunes. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献