310 research outputs found

    Evaluation of remediation agents for DDT- and PCB-contaminated wetlands

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    Wetland sediments that are contaminated with hydrophobic organic compounds, such as dichlorodiphenyltrichloroethane (DDT) and polychlorinated biphenyls (PCBs) can be remediated via in-situ methods. Four different amendment agents, activated carbon, zero valent iron, organoclay and seaweed were assessed. Activated carbon provided the greatest reduction in both PCB and DDx porewater concentrations: an average of 90% or greater reduction of the six congeners detected. Two amendment delivery technologies were evaluated in a microcosm experiment: a granular activated carbon slurry and Aquablok containing powdered activated carbon. The addition of activated carbon via both delivery techniques was found to significantly decrease PCB porewater concentrations (100% reduction)

    A Deep Spitzer Survey of Circumstellar Disks in the Young Double Cluster, h and chi Persei

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    We analyze very deep IRAC and MIPS photometry of ∼\sim 12,500 members of the 14 Myr old Double Cluster, h and χ\chi Persei, building upon on our earlier, shallower Spitzer studies (Currie et al. 2007a, 2008a). Numerous likely members show infrared (IR) excesses at 8 {\mu}m and 24 μ\mum indicative of circumstellar dust. The frequency of stars with 8 μ\mum excess is at least 2% for our entire sample, slightly lower (higher) for B/A stars (later type, lower-mass stars). Optical spectroscopy also identifies gas in about 2% of systems but with no clear trend between the presence of dust and gas. Spectral energy distribution (SED) modeling of 18 sources with detections at optical wavelengths through MIPS 24 μm\mu m reveals a diverse set of disk evolutionary states, including a high fraction of transitional disks, although similar data for all disk-bearing members would provide better constraints. We combine our results with those for other young clusters to study the global evolution of dust/gas disks. For nominal cluster ages, the e-folding times (τo\tau_{o}) for the frequency of warm dust and gas are 2.75 Myr and 1.75 Myr respectively. Assuming a revised set of ages for some clusters (e.g. Bell et al. 2013), these timescales increase to 5.75 and 3.75 Myr, respectively, implying a significantly longer typical protoplanetary disk lifetime. The transitional disk duration, averaged over multiple evolutionary pathways, is ∼\sim 1 Myr. Finally, 24 μ\mum excess frequencies for 4-6 M⊙_{\odot} stars appear lower than for 1-2.5 M⊙_{\odot} stars in other 10-30 Myr old clusters.Comment: 35 pages, 6 tables, 21 figures; Accepted for publication in The Astrophysical Journa

    Positive Youth Development Sustainability Scale (PYDSS): The development of an assessment tool

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    Our study details the development of the Positive Youth Development Sustainability Scale, a self-reporting tool to assess the impacts of positive youth development (PYD) programs. The Positive Youth Development Sustainability Scale provides practitioners a tool in the field of PYD both domestically and internationally, addressing the concern of global application and sustainability criteria (e.g., resilience and happiness). First, we conducted a detailed literature review on existing PYD program assessment techniques. Next, we conducted an exploratory factor analysis, via SPSS and AMOS software, to establish the number of factors in the scale. The constructs of the five-Cs model (Lerner, 2005; competence, confidence, character, connection, and caring) along with the sixth C (contribution) and happiness were confirmed into six factors. Confirmatory factor analysis was conducted using 2 samples from rural areas of Thailand and the Phoenix, Arizona, metro area (n = 580 and n = 407, respectively). Our analysis shows the factor structure was highly comparable with mean comparative fit indices of .930 (Thailand) and .933 (Phoenix metro) for Grades 9–12 and 3–6, respectively. Our study suggests that the tool can be used in different settings and demographics for PYD programs. Future studies should look at the impacts of PYD programs over long periods of time and in a wide range of grades, cultures, and countries to reaffirm multiple applications in various settings

    Happiness in Communities: How Neighborhoods, Cities and States Use Subjective Well-Being Metrics

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    This essay, the fourth and last of a series published by the Journal of Social Change, is intended as a tool for community organizers, local policy makers, researchers, students and others to incorporate subjective well-being indicators into their measurements and management of happiness and well-being in their communities, for policy purposes, for research and for other purposes. It provides case studies of community-based efforts in five different regions (São Paulo, Brazil; Bristol, United Kingdom; Melbourne, Australia; Creston, British Columbia, Canada; and Vermont, United States) that either developed their own subjective well-being index or used the Happiness Alliance’s survey instrument to measure happiness and well-being. The essay offers lessons to consider when using subjective well-being indicator survey instruments. Finally, the essay provides a process for measuring happiness using the Happiness Alliance’s survey instrument

    Association mapping of seed quality traits using the Canadian flax (Linum usitatissimum L.) core collection

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    KEY MESSAGE: The identification of stable QTL for seed quality traits by association mapping of a diverse panel of linseed accessions establishes the foundation for assisted breeding and future fine mapping in linseed. ABSTRACT: Linseed oil is valued for its food and non-food applications. Modifying its oil content and fatty acid (FA) profiles to meet market needs in a timely manner requires clear understanding of their quantitative trait loci (QTL) architectures, which have received little attention to date. Association mapping is an efficient approach to identify QTL in germplasm collections. In this study, we explored the quantitative nature of seed quality traits including oil content (OIL), palmitic acid, stearic acid, oleic acid, linoleic acid (LIO) linolenic acid (LIN) and iodine value in a flax core collection of 390 accessions assayed with 460 microsatellite markers. The core collection was grown in a modified augmented design at two locations over 3 years and phenotypic data for all seven traits were obtained from all six environments. Significant phenotypic diversity and moderate to high heritability for each trait (0.73–0.99) were observed. Most of the candidate QTL were stable as revealed by multivariate analyses. Nine candidate QTL were identified, varying from one for OIL to three for LIO and LIN. Candidate QTL for LIO and LIN co-localized with QTL previously identified in bi-parental populations and some mapped nearby genes known to be involved in the FA biosynthesis pathway. Fifty-eight percent of the QTL alleles were absent (private) in the Canadian cultivars suggesting that the core collection possesses QTL alleles potentially useful to improve seed quality traits. The candidate QTL identified herein will establish the foundation for future marker-assisted breeding in linseed. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s00122-014-2264-4) contains supplementary material, which is available to authorized users

    Happiness Index Methodology

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    The Happiness Index is a comprehensive survey instrument that assesses happiness, well-being, and aspects of sustainability and resilience. The Happiness Alliance developed the Happiness Index to provide a survey instrument to community organizers, researchers, and others seeking to use a subjective well-being index and data. It is the only instrument of its kind freely available worldwide and translated into over ten languages. This instrument can be used to measure satisfaction with life and the conditions of life. It can also be used to define income inequality, trust in government, sense of community and other aspects of well-being within specific demographics of a population. This manuscript documents the development the Happiness Index between 2011 and 2015, and includes suggestions for implementation

    Deep Thermal Infrared Imaging of HR 8799 bcde: New Atmospheric Constraints and Limits on a Fifth Planet

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    We present new L′L^\prime (3.8 μm\mu m) and Br-α\alpha (4.05 μm\mu m) data and reprocessed archival L′L^\prime data for the young, planet-hosting star HR 8799 obtained with Keck/NIRC2, VLT/NaCo and Subaru/IRCS. We detect all four HR 8799 planets in each dataset at a moderate to high signal-to-noise (SNR ≳\gtrsim 6-15). We fail to identify a fifth planet, "HR 8799 f", at rr << 15 AUAU at a 5-σ\sigma confidence level: one suggestive, marginally significant residual at 0.2" is most likely a PSF artifact. Assuming companion ages of 30 MyrMyr and the Baraffe (Spiegel \& Burrows) planet cooling models, we rule out an HR 8799 f with mass of 5 MJM_{J} (7 MJM_{J}), 7 MJM_{J} (10 MJM_{J}), and 12 MJM_{J} (13 MJM_{J}) at rprojr_{proj} ∼\sim 12 AUAU, 9 AUAU, and 5 AUAU, respectively. All four HR 8799 planets have red early T dwarf-like L′L^\prime - [4.05] colors, suggesting that their SEDs peak in between the L′L^\prime and M′M^\prime broadband filters. We find no statistically significant difference in HR 8799 cde's colors. Atmosphere models assuming thick, patchy clouds appear to better match HR 8799 bcde's photometry than models assuming a uniform cloud layer. While non-equilibrium carbon chemistry is required to explain HR 8799 bc's photometry/spectra, evidence for it from HR 8799 de's photometry is weaker. Future, deep IR spectroscopy/spectrophotometry with the Gemini Planet Imager, SCExAO/CHARIS, and other facilities may clarify whether the planets are chemically similar or heterogeneous.Comment: 18 pages, 6 Tables, and 9 Figures. Fig. 1a is the key figure. Accepted for publication in Ap

    Heat rejection sublimator

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    A sublimator includes a sublimation plate having a thermal element disposed adjacent to a feed water channel and a control point disposed between at least a portion of the thermal element and a large pore substrate. The control point includes a sintered metal material. A method of dissipating heat using a sublimator includes a sublimation plate having a thermal element and a control point. The thermal element is disposed adjacent to a feed water channel and the control point is disposed between at least a portion of the thermal element and a large pore substrate. The method includes controlling a flow rate of feed water to the large pore substrate at the control point and supplying heated coolant to the thermal element. Sublimation occurs in the large pore substrate and the controlling of the flow rate of feed water is independent of time. A sublimator includes a sublimation plate having a thermal element disposed adjacent to a feed water channel and a control point disposed between at least a portion of the thermal element and a large pore substrate. The control point restricts a flow rate of feed water from the feed water channel to the large pore substrate independent of time
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