128 research outputs found

    Average sedimentary rock rare Earth element patterns and crustal evolution: Some observations and implications from the 3800 Ma ISUA supracrustal belt, West Greenland

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    Rare earth element (REE) data is given on a set of clastic metasediments from the 3800 Ma Isua Supracrustal belt, West Greenland. Each of two units from the same sedimentary sequence has a distinctive REE pattern, but the average of these rocks bears a very strong resemblance to the REE pattern for the North American Shale Composite (NASC), and departs considerably from previous estimates of REE patterns in Archaean sediments. The possibility that the source area for the Isua sediments resembled that of the NASC is regarded as highly unlikely. However, REE patterns like that in the NASC may be produced by sedimentary recycling of material yielding patterns such as are found at Isua. The results lead to the following tentative conclusions: (1) The REE patterns for Isua Seq. B MBG indicate the existence of crustal materials with fractionated REE and negative Eu anomalies at 3800 Ma, (2) The average Seq. B REE pattern resembles that of the North American Shale Composite (NASC), (3) If the Seq. B average is truly representative of its crustal sources, then this early crust could have been extensively differentiated. In this regard, a proper understanding of the NASC pattern, and its relationship to post-Archaean crustal REE reservoirs, is essential, (4) The Isua results may represent a local effect

    Cerebral blood flow predicts differential neurotransmitter activity

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    Application of metabolic magnetic resonance imaging measures such as cerebral blood flow in translational medicine is limited by the unknown link of observed alterations to specific neurophysiological processes. In particular, the sensitivity of cerebral blood flow to activity changes in specific neurotransmitter systems remains unclear. We address this question by probing cerebral blood flow in healthy volunteers using seven established drugs with known dopaminergic, serotonergic, glutamatergic and GABAergic mechanisms of action. We use a novel framework aimed at disentangling the observed effects to contribution from underlying neurotransmitter systems. We find for all evaluated compounds a reliable spatial link of respective cerebral blood flow changes with underlying neurotransmitter receptor densities corresponding to their primary mechanisms of action. The strength of these associations with receptor density is mediated by respective drug affinities. These findings suggest that cerebral blood flow is a sensitive brain-wide in-vivo assay of metabolic demands across a variety of neurotransmitter systems in humans

    Changes in the Prevalence of Child and Youth Mental Disorders and Perceived Need for Professional Help between 1983 and 2014: Evidence from the Ontario Child Health Study

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    © The Author(s) 2019. Objectives: To examine: 1) changes in the prevalence of mental disorders and perceived need for professional help among children (ages 4 to 11) and youth (ages 12 to 16) between 1983 and 2014 in Ontario and 2) whether these changes vary by age and sex, urban-rural residency, poverty, lone-parent status, and immigrant background. Methods: The 1983 (n = 2836) and 2014 (n = 5785) Ontario Child Health Studies are provincially representative cross-sectional surveys with identical self-report checklist measures of conduct disorder, hyperactivity, and emotional disorder, as well as perceived need for professional help, assessed by integrating parent and teacher responses (ages 4 to 11) and parent and youth responses (ages 12 to 16). Results: The overall prevalence of perceived need for professional help increased from 6.8% to 18.9% among 4- to 16-year-olds. An increase in any disorder among children (15.4% to 19.6%) was attributable to increases in hyperactivity among males (8.9% to 15.7%). Although the prevalence of any disorder did not change among youth, conduct disorder decreased (7.2% to 2.5%) while emotional disorder increased (9.2% to 13.2%). The prevalence of any disorder increased more in rural and small to medium urban areas versus large urban areas. The prevalence of any disorder decreased for children and youth in immigrant but not nonimmigrant families. Conclusions: Although there have been decreases in the prevalence of conduct disorder, increases in other mental disorders and perceived need for professional help underscore the continued need for effective prevention and intervention programs

    Morphological cells in the Ragusa littoral (Sicily, Italy)

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    Geomorphologic information, topographic maps (dated 1967), aerial photographs (dated 1999 and 2008), and spatial analysis procedures were used to investigate a 90 km long coastal sector in South Sicily (Italy). Information was obtained on coastal erosion/accretion areas, general sediment circulation pattern and littoral cell distribution. Human-made structures and natural headlands constituted important artificial limits dividing littoral in morphological cells. Ports and harbours were observed at Scoglitti, Punta Secca, Marina di Ragusa, Donnalucata and Pozzallo. Most of them worked as “transit” limits which interrupted predominant, eastward directed sedimentary transport, this way generating accretion in updrift (west) side of mentioned structures and erosion in downdrift (east) side. During the 1967–2008 period, about 62,000 m2 and 42,000 m2 of beach surface were respectively formed updrift of Scoglitti and Donnalucata ports. The construction of Pozzallo port gave rise to the formation of a “convergent” limit which favoured large accretion (94,000 m2) east of port structure. Most important natural structures were observed at Punta Zafaglione, P. Braccetto and Cava d’Aliga. The knowledge of littoral cell distribution acquires a great importance for appropriate management of coastal erosion processes which may be mitigated installing by-passing systems in ports and harbours and carrying out nourishment works in eroding areas, often located downdrift of ports and harbours (when these structures work as transit limits) and in central part of littoral cells (when these structures work as convergent limits)

    Error determination in the photogrammetric assessment of shoreline changes

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    The evaluation of error or uncertainty in shoreline change studies is an issue of prime importance for providing an adequate framework for calculated rates of change and to allow the establishment of threshold values above which the rates would be significant. In this note, a practical, easy-to-use method is presented to estimate error involved in the calculation of shoreline changes on aerial photographs, including the three most used types of shoreline indicators: high water line, dune/cliff toe and cliff top. This approach takes into account the specific characteristics of each shoreline proxy, such as relief in the case of the cliff top or tidal oscillations in the case of the high water line. At the same time it includes the error components that are independent from the proxy, basically related to the technical aspects of the process such as photo scanning and georeferencing. A practical example of application of the method is provided for several types of data inputs, based on shoreline changes around the Bay of CĂĄdiz (SW Spain)

    Cross-border trafficking in human beings: prevention and intervention strategies for reducing sexual exploitation

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    Over the years, growing attention has been given to the phenomenon of trafficking in human beings (THB). Sexual exploitation was until recently by far the most commonly identified feature of THB, followed by forced labour. Many activities to combat trafficking for the purpose of sexual exploitation have been initiated by numerous supranational, international as well as national organizations. Much is written about these initiatives, but some areas have been neglected. Knowledge on ‘what works’ is in particular limited. The growing attention to THB entails a demand for more information. The severity of the crime and the impact on its victims makes it of utmost importance to gain more insight into the working and effectiveness of anti-trafficking strategies and interventions. The main objective of this review was to assess the presently available evidence on the effects of interventions that aim to prevent and suppress trafficking in human beings

    Inhibitory effect of pre-immunized cba spleen cells on transplants of a-strain mouse mammary carcinoma in (cba x a) f1 hybrid recipients.

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    has been reported previously from this laboratory (Woodruff and Symes, 1962) that the growth of an A-strain mouse mammary carcinoma transplanted to isogenic hosts is retarded if the tumour-inoculated animals are given a sublethal dose of whole body irradiation (400 r) followed by an intravenous injection of spleen cells from a mouse of a different strain (CBA) immunized against the tumour; a significant anti-tumour effect was however achieved only at the cost of producing severe and often fatal graft-versus-host disease in the treated animals. In the experiments cited, irradiation alone, and injection of spleen cells without prior irradiation, were ineffective. It seemed likely that in the combined treatment the effect of the irradiation was to delay rejection of the transplanted spleen cells, but there was no formal proof of this. It appeared desirable, therefore, to make further observations with the same type of tumour but under conditions in which immunological rejection of the transplanted spleen cells could be avoided without recourse to irradiation or the use of immunosuppressive drugs. This requirement can be met by maintaining the tumour in the F1 hybrid of tw
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