8,246 research outputs found

    Preliminary Starch Grain Evidence of Ancient Stone Tool Use at the Early Archaic (9,000 B.P.) Site of Sandy Hill, Mashantucket, Connecticut

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    Early Archaic subsistence strategies of New England remain poorly understood despite their importance in helping researchers understand how people adapt to changing landscapes following the end of the last glacial maximum (21,000-14,000 B.P.). Excavations at the Mashantucket Pequot Reservation in Mashantucket, Connecticut during the 1990s revealed a large, semi-sedentary village nestled alongside a complex wetland ecosystem. In this paper, we present preliminary starch grain analysis of several stone tools recovered and curated from these excavations. The results of this study indicate that both transitory and reserve starch grains are preserved on these artifacts and that at least one of the artifacts may have been used for leaf or stem processing. The results of this study also demonstrate the potential for future research in which paired macrobotanical and residue analysis will allow for a better understanding of subsistence practices at the site and during the early Archaic in general.</p

    Scattering a pulse from a chaotic cavity: Transitioning from algebraic to exponential decay

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    The ensemble averaged power scattered in and out of lossless chaotic cavities decays as a power law in time for large times. In the case of a pulse with a finite duration, the power scattered from a single realization of a cavity closely tracks the power law ensemble decay initially, but eventually transitions to an exponential decay. In this paper, we explore the nature of this transition in the case of coupling to a single port. We find that for a given pulse shape, the properties of the transition are universal if time is properly normalized. We define the crossover time to be the time at which the deviations from the mean of the reflected power in individual realizations become comparable to the mean reflected power. We demonstrate numerically that, for randomly chosen cavity realizations and given pulse shapes, the probability distribution function of reflected power depends only on time, normalized to this crossover time.Comment: 23 pages, 5 figure

    Physiological response to groundwater depth varies among species and with river flow regulation

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    We investigated the physiological response of two native riparian tree species (Populus fremontii and Salix gooddingii) and one exotic species (Tamarix chinensis) to groundwater availability along gradients of depth to groundwater at two rivers in Arizona. Depth to groundwater (DGW) at the dam-regulated Bill Williams River (BWR) was relatively constant and shallow (,4 m). Populus fremontii at BWR did not experience reduced water availability at deeper groundwater depths, as evidenced by high predawn water potential. However, leaf gas exchange of P. fremontii was sensitive to high vapor pressure deficit where surface flow was ephemeral at BWR. Lower predawn water potentials of S. gooddingii at BWR suggested reduced water availability at deeper groundwater depths, but these reductions did not adversely affect net photosynthetic rate. Along the range of depth to groundwater at BWR, all three species suffered little canopy dieback, and dieback was not related to depth to groundwater. Depth to groundwater at the free-flowing Hassayampa River (HRP) was much greater and declined more rapidly in the ephemeral reaches than at BWR. Both P. fremontii and S. gooddingii experienced reduced water availability at deeper groundwater depths at HRP, as evidenced by lower predawn water potential. Both species also experienced reduced leaf gas exchange at deeper groundwater depths. Canopy dieback of all species was higher at HRP than at BWR and increased with increasing DGW, especially when DGW fell below 3 m. There was evidence to support branch sacrifice in these three riparian tree species as a means of improving water status in the surviving shoot. However, branch sacrifice was insufficient to prevent mortality in some of the native trees where DGW fell below 3 m at HRP. In contrast to the native species, T. chinensis showed no change in water availability, leaf gas exchange, or canopy dieback with increasing DGW at either river. Leaf gas exchange was lower and dieback was greater for T. chinensis at HRP where depth to groundwater was greater than at BWR, but there was no mortality at either river. Our results show that deep groundwater is more detrimental to the physiological condition of P. fremontii and S. gooddingii than it is to T. chinensis. Also, the pronounced differences in DGW and tree physiological performance between BWR and HRP suggest that dam regulation can increase water availability to mature trees in some desert riparian ecosystems. Finally, our study also provides estimates of the range of DGW that can maintain healthy, mature P. fremontii and S. gooddingii trees

    Evaluation of Chelating Agents Used in Phytoextraction by Switchgrass of Lead Contaminated Soil

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    Soil lead (Pb) contamination is a recognized environmental and global health problem. Phytoextraction of Pb using switchgrass (Panicum virgatum L.), a second-generation biofuel crop, is typically enhanced by soil chelation. The effectiveness of four different chelating agents, phytic acid (inositol hexaphosphate), citric acid, NTA (nitrilotriacetic acid), and EDTA (ethylenediaminetetraacetic acid) was examined in pot culture. Plants treated with EDTA (1 mM) showed significantly higher shoot Pb concentrations compared to control plants and plants treated with other chelates. Lead-solubility following phytoextraction was examined by soil washing using 0.01 and 0.05 M acetic acid as an extractant solution revealed no significant differences in Pb concentrations in soil among different chelate treatments and control. Furthermore, the effects of different concentrations (1, 2, 5 and 10 mM) of NTA on Pb phytoextraction of switchgrass were examined. Plants receiving 5 mM and 10 mM NTA had significantly higher foliage concentrations of Pb compared to plants treated with lower levels (1 and 2 mM) of NTA. Moreover, the effect of NTA application alone was significantly improved by a combined application of Triton X-100, an alkyl polyglucoside (APG); the Pb concentration in the foliage of switchgrass was more than doubled when treated with NTA combined with APG. The use of NTA combined with APG has great potential in improving phytoextraction efficiencies of switchgrass on Pb-contaminated soils

    What Works to Prevent Sexual Violence Against Children

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    The data is clear: Sexual violence affects girls and boys in every country around the world. For far too long it has been a silent pandemic, with little awareness of the scope, scale, and consequences of the problem or understanding of potential solutions. That silence has allowed violence against children to perpetuate. However, there is hope. Recently, there has been a global awakening to the issue of sexual violence against children. While there has been little conversation around solutions to prevent sexual violence, this document intends to change that. By analyzing the best available research on existing strategies and identifying the most effective and promising solutions, we have created a resource for decision-makers, advocates, and program implementers, showcasing what works to prevent sexual violence in childhood and adolescence. Building off the INSPIRE framework “Seven Strategies to Prevent Violence Against Children,” this evidence review looked at strategies specifically focused on preventing sexual violence. We then categorized these interventions as effective, promising, prudent, conflicting, no effect, or harmful. From school-based, safe-dating programs to community mobilization efforts, these evidence-based solutions showcase that there are practical, cost-effective programs that can help break the cycle of violence. The evidence shows that sexual violence can — and must — be prevented. Now it’s on us to bring these solutions to scale. Together, we can create a safer world for every child

    Duration of Posttraumatic Amnesia Predicts Neuropsychological and Global Outcome in Complicated Mild Traumatic Brain Injury.

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    OBJECTIVES: Examine the effects of posttraumatic amnesia (PTA) duration on neuropsychological and global recovery from 1 to 6 months after complicated mild traumatic brain injury (cmTBI). PARTICIPANTS: A total of 330 persons with cmTBI defined as Glasgow Coma Scale score of 13 to 15 in emergency department, with well-defined abnormalities on neuroimaging. METHODS: Enrollment within 24 hours of injury with follow-up at 1, 3, and 6 months. MEASURES: Glasgow Outcome Scale-Extended, California Verbal Learning Test II, and Controlled Oral Word Association Test. Duration of PTA was retrospectively measured with structured interview at 30 days postinjury. RESULTS: Despite all having a Glasgow Coma Scale Score of 13 to 15, a quarter of the sample had a PTA duration of greater than 7 days; half had PTA duration of 1 of 7 days. Both cognitive performance and Extended Glasgow Outcome Scale outcomes were strongly associated with time since injury and PTA duration, with those with PTA duration of greater than 1 week showing residual moderate disability at 6-month assessment. CONCLUSIONS: Findings reinforce importance of careful measurement of duration of PTA to refine outcome prediction and allocation of resources to those with cmTBI. Future research would benefit from standardization in computed tomographic criteria and use of severity indices beyond Glasgow Coma Scale to characterize cmTBI

    Love, rights and solidarity: studying children's participation using Honneth's theory of recognition

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    Recent attempts to theorize children’s participation have drawn on a wide range of ideas, concepts and models from political and social theory. The aim of this article is to explore the specific usefulness of Honneth’s theory of a ‘struggle for recognition’ in thinking about this area of practice. The article identifies what is distinctive about Honneth’s theory of recognition, and how it differs from other theories of recognition. It then considers the relevance of Honneth’s conceptual framework to the social position of children, including those who may be involved in a variety of ‘participatory’ activities. It looks at how useful Honneth’s ideas are in direct engagement with young people’s praxis, drawing on ethnographic research with members of a children and young people’s forum. The article concludes by reflecting on the implications of this theoretical approach and the further questions which it opens up for theories of participation and of adult–child relations more generally
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