585 research outputs found

    Valuing local perspectives on invasive species management: Moving beyond the ecosystem service-disservice dichotomy

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    This paper uses the concept of ecosystem disservices to explore and understand how rapid environmental change associated with an invasive plant species is framed and understood by different stakeholders. Through a focus on narratives, the paper explores how socially-differentiated populations understand the causes and consequences of a plant invasion and express preferences for often contrasting management interventions. The research design uses a workshop format to instigate a series of conversations with socially-differentiated groups of people to explore how people perceive and respond to the impact of Prosopis juliflora (a species of mesquite) in the drylands of Ethiopia. The results show that preferences for interventions differs by age, gender, location and livelihood and also by primary and secondary stakeholder. Different sets of values underpin people’s views and these contribute to the variation in the preference for different management interventions. To understand complex issues associated with alien invasive species, we find that the dichotomy between ecosystem services and disservices is artificial and call for a more dynamic and graduated view of ecosystem outputs. More practically, our research shows that P. juliflora management options need wider consideration of socially-differentiated implications and trade-offs and this requires greater efforts to engage with primary stakeholders

    Modeling & Simulation Education for the Acquisition and T&E Workforce: FY07 Deliverable Package

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    This report was prepared for CAPT Mike Lilienthal, PhD, CPE, and funded by ASN (RDA) CHENG and the Modeling and Simulation Coordination Office (MSCO).This technical report presents the deliverables for calendar year 2007 for the "Educating the Modeling and Simulation Workforce" project performed for the DoD Modeling and Simulation Steering Committee. It includes the results for spirals one and two. Spiral one is an analysis of the educational needs of the program manager, systems engineer, and test and evaluation workforces against a set of educational skill requirements developed by the project team. This is referred to as the 'learning matrix'. Spiral two is a set of module and course matrices, along with delivery options, that meets the educational needs indentified in spiral one. This is referred to as the 'learning architecture'. Supporting materials, such as case studies and a handbook, are included. These documents serve as the design framework for spirals three and four, to be completed in CY2008, and which involve the actual production and testing of the courses in the learning architecture and their longitudinal assessment. This report includes the creative work of a seven university consortium and a group of M&S stake-holders, together comprising over 60 personnel.ASN (RDA) CHENG and the Modeling and Simulation Coordination Office (MSCO).This report was prepared for CAPT Mike Lilienthal, PhD, CPE, and funded by ASN (RDA) CHENG and the Modeling and Simulation Coordination Office (MSCO)

    Probing the Evolution of the Galaxy Interaction/Merger Rate Using Collisional Ring Galaxies

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    We present the results from our program to determine the evolution of the galaxy interaction/merger rate with redshift using the unique star-forming characteristics of collisional ring galaxies. We have identified 25 distant collisional ring galaxy candidates (CRGCs) in a total of 162 deep Hubble Space Telescope Wide Field/Planetary Camera-2 images obtained from the HST Archives. Based on measured and estimated redshifts, these 25 CRGCs all lie in the redshift interval of 0.1 < z < 1. Using the local collisional ring galaxy volume density and the new ``standard'' cosmology, we find that in order to account for the number of identified CRGCs in our surveyed fields, the galaxy interaction/merger rate, parameterized as (1 + z)^m, must increase steeply with redshift.We determine a minimum value of m = 5.2 ±\pm 0.7, though m could be as high as 7 or 8. We can rule out a non-evolving (m = 0) and weakly evolving (m = 1-2) galaxy interaction/merger rate at greater than the 4 sigma level of confidence.Comment: Accepted in the Astrophysical Journal (11 pages, 4 figures). Higher resolution version of the figures is available at http://www.astro.cornell.edu/~vassilis/papers

    Do ultrafast exciton-polaron decoherence dynamics govern photocarrier generation efficiencies in polymer solar cells?

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    All-organic-based photovoltaic solar cells have attracted considerable attention because of their low-cost processing and short energy payback time. In such systems the primary dissociation of an optical excitation into a pair of photocarriers has been recently shown to be extremely rapid and efficient, but the physical reason for this remains unclear. Here, two-dimensional photocurrent excitation spectroscopy, a novel non-linear optical spectroscopy, is used to probe the ultrafast coherent decay of photoexcitations into charge-producing states in a polymer:fullerene based solar cell. The two-dimensional photocurrent spectra are interpreted by introducing a theoretical model for the description of the coupling of the electronic states of the system to an external environment and to the applied laser fields. The experimental data show no cross-peaks in the two-dimensional photocurrent spectra, as predicted by the model for coherence times between the exciton and the photocurrent producing states of 20\,fs or less

    Floods and health in Gambella region, Ethiopia: a qualitative assessment of the strengths and weaknesses of coping mechanisms

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    BACKGROUND: Floods are the most frequent and devastating type of natural disaster worldwide, causing unprecedented deaths, diseases, and destruction of property and crops. Flooding has a greater impact in developing countries due to lack of sufficient disaster management structures and a lack of economic resources. OBJECTIVE: This study was conducted with the aim of contributing to the knowledge base of development strategies that reduce flood-related health risks in developing countries. The study focused particularly on assessing the flood risks and health-related issues in the Gambella region of Ethiopia; with the intent of producing relevant information to assist with the improvements in the efficacy of the current flood coping strategies in the region. METHODS: Data were gathered through interviews with 14 officers from different government and non-governmental organizations and a questionnaire survey given to 35 flood victims in Itang woreda. A qualitative approach was applied and the data were analyzed using content analysis. RESULTS: It was found that flooding is a common problem in Gambella region. The findings also indicate that the flood frequency and magnitude has increased rapidly during the last decade. The increase in floods was driven mainly by climate change and changes in land use, specifically deforestation. The reported main impacts of flooding on human health in Gambella region were deaths, injuries, and diseases such as malaria and diarrhea. Another notable consequence of flooding was crop destruction and subsequent malnutrition. CONCLUSIONS: Three weaknesses that were identified in the current coping strategies for flood-related health impacts in Gambella region were a lack of flood-specific policy, absence of risk assessment, and weak institutional capacity. This study recommends new policy approaches that will increase the effectiveness of the current flood coping strategies to sustainably address the impact of flooding on human health

    The stellar metallicity distribution of disc galaxies and bulges in cosmological simulations

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    By means of high-resolution cosmological hydrodynamical simulations of Milky Way-like disc galaxies, we conduct an analysis of the associated stellar metallicity distribution functions (MDFs). After undertaking a kinematic decomposition of each simulation into spheroid and disc sub-components, we compare the predicted MDFs to those observed in the solar neighbourhood and the Galactic bulge. The effects of the star formation density threshold are visible in the star formation histories, which show a modulation in their behaviour driven by the threshold. The derived MDFs show median metallicities lower by 0.2-0.3 dex than the MDF observed locally in the disc and in the Galactic bulge. Possible reasons for this apparent discrepancy include the use of low stellar yields and/or centrally-concentrated star formation. The dispersions are larger than the one of the observed MDF; this could be due to simulated discs being kinematically hotter relative to the Milky Way. The fraction of low metallicity stars is largely overestimated, visible from the more negatively skewed MDF with respect to the observational sample. For our fiducial Milky Way analog, we study the metallicity distribution of the stars born "in situ" relative to those formed via accretion (from disrupted satellites), and demonstrate that this low-metallicity tail to the MDF is populated primarily by accreted stars. Enhanced supernova and stellar radiation energy feedback to the surrounding interstellar media of these pre-disrupted satellites is suggested as an important regulator of the MDF skewness.Comment: 20 pages, 14 figures, MNRAS, accepte

    “We can’t do it on our own!”—Integrating stakeholder and scientific knowledge of future flood risk to inform climate change adaptation planning in a coastal region

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    Decision-makers face a particular challenge in planning for climate adaptation. The complexity of climate change's likely impacts, such as increased flooding, has widened the scope of information necessary to take action. This is particularly the case in valuable low-lying coastal regions, which host many competing interests, and where there is a growing need to draw from varied fields in the risk-based management of flooding. The rising scrutiny over science's ability to match expectations of policy actors has called for the integration of stakeholder and scientific knowledge domains. Focusing on the Broads — the United Kingdom's largest protected wetland — this study looked to assess future flood risk and consider potential adaptation responses in a collaborative approach. Interviews and surveys with local stakeholders accompanied the development of a hydraulic model in an iterative participatory design, centred on a scientist-stakeholder workshop. Knowledge and perspectives were shared on processes driving risk in the Broads, as well as on the implications of adaptation measures, allowing for their prioritisation. The research outcomes highlight not only the challenges that scientist-stakeholder integrated assessments of future flood risk face, but also their potential to lead to the production of useful information for decision-making

    Optimization of Monoclonal Antibodies Purification Expressed in H-192 cells using Preparative Native-Polyacrylamide Gel Electrophoresis

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    Monoclonal antibodies (mAbs) are unique and specific drug molecules targeting the treatment of various diseases such as arthritis, immune disorders, infectious diseases, and cancer etc. Different methods such as antibody coupled affinity chromatography, hydrophobic interaction chromatography, etc., can be applied to purify mAbs from various sources. This article provides a simple, cost effective, preparative native-polyacrylamide gel electrophoresis (n-PAGE) technique to purify mAbs expressed in H-192 cells (Hybridoma murine cell lines) against an antigen i.e. 17-alpha-hydroxyprogesterone (17-OHP), which further can have diagnostic application to detect Congenital Adrenal Hyperplasia (CAH). Furthermore, different parameters such as concentration and volume of the feedstock (medium containing antibodies), pore size of gel, height of resolving gel etc. were optimized to obtain the maximum purity and yield of mAbs

    Risk map as a library management information dashboard: a case study in adapting a configural display

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    In this paper, we report on our application of Cognitive Work Analysis to create an Abstraction Hierarchy model that helps librarians identify key functional relationships for managing the overall performance of a library. By themselves, functional relationships are not as useful in providing insights into the reasons for good or poor performance. However, when these functional relationships are set against the context of system invariants and constraints, they can provide library managers information useful for diagnosis and localization of problems. We propose the Risk Map visualization technique as an information dashboard to cognitively access these functional relationships. Furthermore, when these functional relationships are portrayed over time, trends and patterns can be detected with relative ease
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