718 research outputs found

    Report on the Forest Sector Project Network Meeting: 29 August - 2 September 1983 - Sopron, Hungary

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    As at the two previous network meetings, the 1983 Forest Sector Project Network Meeting summarized the accomplishments of the Project, both by the staff at IIASA in Laxenburg, Austria, and by the national teams in collaborating countries. Also discussed were options for future effort (particularly for further development of the global forest trade model), data required to be assembled and analyzed, and other Forest Sector Project affairs. A detailed agenda is listed in Appendix A. The network meeting was attended by 39 participants from 13 of the collaborating countries and from cooperating organizations (Food and Agriculture Organization of United Nations (FAO), United Nations Industrial Development Organization (UNIDO), and Jaakko Poyry International Oy). Eight members of IIASA's Forest Sector Project and other units participated. A list of participants is given in Appendix B. Unlike other network meetings, the meeting was held in Sopron, Hungary, because accommodations were unexpectedly scarce near Vienna. The participants were appreciative of the gracious and generous hospitality of our hosts, the Hungarian Committee for Applied Systems Analysis. Formal presentations are only part of what happens at any coordinating meeting. Questions and comments during the meeting, conversations at breaks and meals, distribution of papers by those that could not attend, and separate meetings on special topics all contributed to accomplishments. This report attempts to summarize the meeting as a whole

    INFORMATION TECHNOLOGY AND ECONOMIC REORGANIZATION

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    Information Technology (IT) can support or even cause changes in the structure of industries and the relationships between firms. Yet, at present, we lack the vocabulary and theory to explain or predict these changes. Drawing on recent work in the resource-based theory of the firm, we propose that shifts in resource values are central to economic restructuring. We show how IT can operate to shift resource values through the basic economic drivers of network externalities and economies of scale, scope, and specialization. We use this theory to investigate the situations that will lead to each of the basic structural responses: changes in market consolidation, in diversification, and in vertical integration. We also can make some specific statements about what forms can be employed in the structural responses: ownership, outsourcing, or cooperation

    Forest Sector Models

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    These proceedings of the NORTH AMERICAN CONFERENCE ON FOREST SECTOR MODELS represent not only individual contributions of some 40 researchers, but also significant progress of an unique international effort in forestry research: The Forest Sector Project of the International Institute for Applied Systems Analysis (IIASA). The project is a joint effort of researchers in over 15 nations to cooperatively develop models of their forest sectors that can be linked together to form an international model useful for projecting the development of resources, the progress of industry, and the flows of trade worldwide. Such linkage of models has never been attempted in forestry

    Origami constraints on the initial-conditions arrangement of dark-matter caustics and streams

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    In a cold-dark-matter universe, cosmological structure formation proceeds in rough analogy to origami folding. Dark matter occupies a three-dimensional 'sheet' of free- fall observers, non-intersecting in six-dimensional velocity-position phase space. At early times, the sheet was flat like an origami sheet, i.e. velocities were essentially zero, but as time passes, the sheet folds up to form cosmic structure. The present paper further illustrates this analogy, and clarifies a Lagrangian definition of caustics and streams: caustics are two-dimensional surfaces in this initial sheet along which it folds, tessellating Lagrangian space into a set of three-dimensional regions, i.e. streams. The main scientific result of the paper is that streams may be colored by only two colors, with no two neighbouring streams (i.e. streams on either side of a caustic surface) colored the same. The two colors correspond to positive and negative parities of local Lagrangian volumes. This is a severe restriction on the connectivity and therefore arrangement of streams in Lagrangian space, since arbitrarily many colors can be necessary to color a general arrangement of three-dimensional regions. This stream two-colorability has consequences from graph theory, which we explain. Then, using N-body simulations, we test how these caustics correspond in Lagrangian space to the boundaries of haloes, filaments and walls. We also test how well outer caustics correspond to a Zel'dovich-approximation prediction.Comment: Clarifications and slight changes to match version accepted to MNRAS. 9 pages, 5 figure

    Second-generation nitazoxanide derivatives: thiazolides are effective inhibitors of the influenza A virus

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    Aim: The only small molecule drugs currently available for treatment of influenza A virus (IAV) are M2 ion channel blockers and sialidase inhibitors. The prototype thiazolide, nitazoxanide, has successfully completed Phase III clinical trials against acute uncomplicated influenza. Results: We report the activity of seventeen thiazolide analogs against A/PuertoRico/8/1934(H1N1), a laboratory-adapted strain of the H1N1 subtype of IAV, in a cell culture-based assay. A total of eight analogs showed IC50s in the range of 0.14–5.0 μM. Additionally a quantitative structure–property relationship study showed high correlation between experimental and predicted activity based on a molecular descriptor set. Conclusion: A range of thiazolides show useful activity against an H1N1 strain of IAV. Further evaluation of these molecules as potential new small molecule therapies is justified

    (2R*,3R*,4aS*,6aR*,11aS*,11bS*)-Methyl 2-acet­oxy-11b-hydr­oxy-3,7-dimethyl-1,2,3,4,4a,5,6,6a,7,11,11a,11b-dodeca­hydro­phenanthro[3,2-b]furan-3-carboxyl­ate

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    In the title compound, C22H30O6, the conformation of the mol­ecule is dictated by an intra­molecular C—H⋯O contact. The crystal structure is stabilized via inter­molecular C—H⋯O, O—H⋯O and C—H⋯π contacts

    Distribution of priority grassland bird habitats in the Prairie Pothole Region of Canada

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    Grassland ecosystems and the species that rely on them are one of the most urgent habitat conservation concerns in North America. Fundamental to any landscape conservation efforts is the identification of priority habitats to help target management efforts. Many avian species associated with prairie ecosystems have experienced population declines along with continued loss of prairie habitats. Additionally, given the long history of research in avian systems and the close grassland associations of some species, birds are excellent candidate taxa for the identification of priority habitats and can provide an informed starting point for multispecies assessments. We used data from the North American Breeding Bird Survey (1997-2014) to develop species distribution models for 15 grassland bird species across the Prairie Pothole Region of Canada. Model performance varied widely across species. Ten species demonstrated good model performance (average Boyce Index > 0.64 across 5-fold cross validation). We used these 10 species to assess the influence of habitat covariates on the relative probability of occurrence, to compare the spatial scales of selection, and to generate multispecies habitat priority maps. Of the nine habitat covariates considered, most species predictably demonstrated positive associations with grassland habitats and avoidance of areas of high tree and shrub cover. Two covariates representing wetland abundance were also frequently included in the top models. The area covered by wetlands (w.area) was present in the top model for 5 of 10 species with a consistently estimated negative coefficient. However, a covariate, which represented the number of wetland basins (w.basins), was present in the top model for 8 of 10 species with an estimated positive coefficient for all but 1 species, representing a preference for more heterogeneous wetland landscapes. The larger spatial scales we considered tended to have greater explanatory power than smaller spatial scales and were thus more prevalent in the top models. The multispecies priority habitat maps that we produced can be used for future assessments of potential habitat management actions. Our work provides a critical foundation for the incorporation of grassland bird conservation goals into on-going landscape-planning initiatives in the Prairie Pothole Region of Canada

    Developing approaches for linear mixed modeling in landscape genetics through landscape-directed dispersal simulations

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    Dispersal can impact population dynamics and geographic variation, and thus, genetic approaches that can establish which landscape factors influence population connectivity have ecological and evolutionary importance. Mixed models that account for the error structure of pairwise datasets are increasingly used to compare models relating genetic differentiation to pairwise measures of landscape resistance. A model selection framework based on information criteria metrics or explained variance may help disentangle the ecological and landscape factors influencing genetic structure, yet there are currently no consensus for the best protocols. Here, we develop landscape-directed simulations and test a series of replicates that emulate independent empirical datasets of two species with different life history characteristics (greater sage-grouse; eastern foxsnake). We determined that in our simulated scenarios, AIC and BIC were the best model selection indices and that marginal R-2 values were biased toward more complex models. The model coefficients for landscape variables generally reflected the underlying dispersal model with confidence intervals that did not overlap with zero across the entire model set. When we controlled for geographic distance, variables not in the underlying dispersal models (i.e., nontrue) typically overlapped zero. Our study helps establish methods for using linear mixed models to identify the features underlying patterns of dispersal across a variety of landscapes.Endangered Species Recovery Fund (WWF, Environment Canada, Ontario Ministry of Natural Resources)US Bureau of Land ManagementUS Geological SurveyWyoming Game and Fish Departmen

    Intermittent Hypoxia-Induced Cognitive Deficits Are Mediated by NADPH Oxidase Activity in a Murine Model of Sleep Apnea

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    Background: In rodents, exposure to intermittent hypoxia (IH), a hallmark of obstructive sleep apnea (OSA), is associated with neurobehavioral impairments, increased apoptosis in the hippocampus and cortex, as well as increased oxidant stress and inflammation. Excessive NADPH oxidase activity may play a role in IH-induced CNS dysfunction. Methods and Findings: The effect of IH during light period on two forms of spatial learning in the water maze and well as markers of oxidative stress was assessed in mice lacking NADPH oxidase activity (gp91phox _/Y) and wild-type littermates. On a standard place training task, gp91phox _/Y displayed normal learning, and were protected from the spatial learning deficits observed in wild-type littermates exposed to IH. Moreover, anxiety levels were increased in wild-type mice exposed to IH as compared to room air (RA) controls, while no changes emerged in gp91phox _/Y mice. Additionally, wild-type mice, but not gp91phox _/Y mice had significantly elevated levels of NADPH oxidase expression and activity, as well as MDA and 8-OHDG in cortical and hippocampal lysates following IH exposures. Conclusions: The oxidative stress responses and neurobehavioral impairments induced by IH during sleep are mediated, at least in part, by excessive NADPH oxidase activity, and thus pharmacological agents targeting NADPH oxidase may provid

    Landscape characteristics influencing the genetic structure of greater sage-grouse within the stronghold of their range: a holistic modeling approach

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    Given the significance of animal dispersal to population dynamics and geographic variability, understanding how dispersal is impacted by landscape patterns has major ecological and conservation importance. Speaking to the importance of dispersal, the use of linear mixed models to compare genetic differentiation with pairwise resistance derived from landscape resistance surfaces has presented new opportunities to disentangle the menagerie of factors behind effective dispersal across a given landscape. Here, we combine these approaches with novel resistance surface parameterization to determine how the distribution of high- and low-quality seasonal habitat and individual landscape components shape patterns of gene flow for the greater sage-grouse (Centrocercus urophasianus) across Wyoming. We found that pairwise resistance derived from the distribution of low-quality nesting and winter, but not summer, seasonal habitat had the strongest correlation with genetic differentiation. Although the patterns were not as strong as with habitat distribution, multivariate models with sagebrush cover and landscape ruggedness or forest cover and ruggedness similarly had a much stronger fit with genetic differentiation than an undifferentiated landscape. In most cases, landscape resistance surfaces transformed with 17.33-km-diameter moving windows were preferred, suggesting small-scale differences in habitat were unimportant at this large spatial extent. Despite the emergence of these overall patterns, there were differences in the selection of top models depending on the model selection criteria, suggesting research into the most appropriate criteria for landscape genetics is required. Overall, our results highlight the importance of differences in seasonal habitat preferences to patterns of gene flow and suggest the combination of habitat suitability modeling and linear mixed models with our resistance parameterization is a powerful approach to discerning the effects of landscape on gene flow.U.S. Bureau of Land ManagementU.S. Geological SurveyWyoming Game and Fish Departmen
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