10,962 research outputs found

    Establishment, Impacts, and Current Range of Spotted Knapweed (\u3ci\u3eCentaurea Stoebe\u3c/i\u3e Ssp. \u3ci\u3eMicranthos\u3c/i\u3e) Biological Control Insects in Michigan

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    Centaurea stoebe L. ssp. micranthos (Gugler) Hayek (spotted knapweed) is an invasive plant that has been the target of classical biological control in North America for more than four decades. Work in the western U.S. and Canada has shown the seedhead-feeding weevils Larinus minutus Gyllenhal and Larinus obtusus Gyllenhal (Coleoptera: Curculionidae) and the root-boring weevil Cyphocleonus achates (Fahraeus) (Coleoptera: Curculionidae) to be the most effective C. stoebe control agents. These three weevils have recently been introduced into the eastern U.S., including sites in Michigan in 2007 and 2009. In 2010, we made additional releases at six sites in Michigan, monitoring them for three years 2011-13. Here we report on the establishment, impact, and cur- rent range of L. minutus, L. obtusus, and C. achates in Michigan. We also report on the initial results of native plant overseeding treatments that were applied to biological control release sites with the aim of supplementing the nectar source C. stoebe provides. We found that L. minutus has established at all of its Michigan release sites and is widespread in the southwestern part of the state, while L. obtusus has established at the single site where it was released in 2007 and is spreading to adjoining counties. We also found C. achates to be present at four sites and established at one additional site in Michigan, but in all cases abundances are low and dispersal has been minimal (\u3c 10 m). In the three years following the 2010 releases, we found no measurable impacts of these biological control agents on C. stoebe growth, demographics, or plant community metrics. We also found little evidence of native flowering plant establishment at seeded sites. These baseline data will be useful in monitoring the spread and potential impacts of biological control agents on C. stoebe in Michigan

    Frequency control in synchronized networks of inhibitory neurons

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    We analyze the control of frequency for a synchronized inhibitory neuronal network. The analysis is done for a reduced membrane model with a biophysically-based synaptic influence. We argue that such a reduced model can quantitatively capture the frequency behavior of a larger class of neuronal models. We show that in different parameter regimes, the network frequency depends in different ways on the intrinsic and synaptic time constants. Only in one portion of the parameter space, called `phasic', is the network period proportional to the synaptic decay time. These results are discussed in connection with previous work of the authors, which showed that for mildly heterogeneous networks, the synchrony breaks down, but coherence is preserved much more for systems in the phasic regime than in the other regimes. These results imply that for mildly heterogeneous networks, the existence of a coherent rhythm implies a linear dependence of the network period on synaptic decay time, and a much weaker dependence on the drive to the cells. We give experimental evidence for this conclusion.Comment: 18 pages, 3 figures, Kluwer.sty. J. Comp. Neurosci. (in press). Originally submitted to the neuro-sys archive which was never publicly announced (was 9803001

    Apollo experience report: Development of the extravehicular mobility unit

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    The development and performance history of the Apollo extravehicular mobility unit and its major subsystems is described. The three major subsystems, the pressure garment assembly, the portable life-support system, and the oxygen purge system, are defined and described in detail as is the evolutionary process that culminated in each major subsystem component. Descriptions of ground-support equipment and the qualification testing process for component hardware are also presented

    Second-generation PLINK: rising to the challenge of larger and richer datasets

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    PLINK 1 is a widely used open-source C/C++ toolset for genome-wide association studies (GWAS) and research in population genetics. However, the steady accumulation of data from imputation and whole-genome sequencing studies has exposed a strong need for even faster and more scalable implementations of key functions. In addition, GWAS and population-genetic data now frequently contain probabilistic calls, phase information, and/or multiallelic variants, none of which can be represented by PLINK 1's primary data format. To address these issues, we are developing a second-generation codebase for PLINK. The first major release from this codebase, PLINK 1.9, introduces extensive use of bit-level parallelism, O(sqrt(n))-time/constant-space Hardy-Weinberg equilibrium and Fisher's exact tests, and many other algorithmic improvements. In combination, these changes accelerate most operations by 1-4 orders of magnitude, and allow the program to handle datasets too large to fit in RAM. This will be followed by PLINK 2.0, which will introduce (a) a new data format capable of efficiently representing probabilities, phase, and multiallelic variants, and (b) extensions of many functions to account for the new types of information. The second-generation versions of PLINK will offer dramatic improvements in performance and compatibility. For the first time, users without access to high-end computing resources can perform several essential analyses of the feature-rich and very large genetic datasets coming into use.Comment: 2 figures, 1 additional fil

    The Rachel Carson Letters and the Making of Silent Spring

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    Environment, conservation, green, and kindred movements look back to Rachel Carson’s 1962 book Silent Spring as a milestone. The impact of the book, including on government, industry, and civil society, was immediate and substantial, and has been extensively described; however, the provenance of the book has been less thoroughly examined. Using Carson’s personal correspondence, this paper reveals that the primary source for Carson’s book was the extensive evidence and contacts compiled by two biodynamic farmers, Marjorie Spock and Mary T. Richards, of Long Island, New York. Their evidence was compiled for a suite of legal actions (1957-1960) against the U.S. Government and that contested the aerial spraying of dichlorodiphenyltrichloroethane (DDT). During Rudolf Steiner’s lifetime, Spock and Richards both studied at Steiner’s Goetheanum, the headquarters of Anthroposophy, located in Dornach, Switzerland. Spock and Richards were prominent U.S. anthroposophists, and established a biodynamic farm under the tutelage of the leading biodynamics exponent of the time, Dr. Ehrenfried Pfeiffer. When their property was under threat from a government program of DDT spraying, they brought their case, eventually lost it, in the process spent US$100,000, and compiled the evidence that they then shared with Carson, who used it, and their extensive contacts and the trial transcripts, as the primary input for Silent Spring. Carson attributed to Spock, Richards, and Pfeiffer, no credit whatsoever in her book. As a consequence, the organics movement has not received the recognition, that is its due, as the primary impulse for Silent Spring, and it is, itself, unaware of this provenance

    Automated CPX support system preliminary design phase

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    The development of the Distributed Command and Control System (DCCS) is discussed. The development of an automated C2 system stimulated the development of an automated command post exercise (CPX) support system to provide a more realistic stimulus to DCCS than could be achieved with the existing manual system. An automated CPX system to support corps-level exercise was designed. The effort comprised four tasks: (1) collecting and documenting user requirements; (2) developing a preliminary system design; (3) defining a program plan; and (4) evaluating the suitability of the TRASANA FOURCE computer model

    Inclusion Of The Spatial Dimension Of Population Data In Developing Policies For The Management Of AnGR –The Case Of The Heritage Sheep Breeds

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    The sustainable use of farm animal genetic resources is connected with the recognition of their contribution to the society and the environment and the assessment of the threats they are facing. The category of the heritage breeds, which are genetically distinct, geographically concentrated, adapted to their environment, commercially farmed to contribute to the local economy were considered in the frame of the HERITAGESHEEP project. The aim of this project was to deliver the potential of the heritage sheep breeds for a sustainable future for medium to low input production systems, which support local rural communities throughout Europe. This was achieved by addressing the conservation of these breeds, defining the current and future threats and developing new uses and markets for products

    Differentiating Between Delinquent Groups and Gangs: Moving Beyond Offending Consequences

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    Even when controlling for high levels of delinquent peers, gang youth differ from their nongang counterparts on a variety of attitudinal and behavioral measures. Researchers have argued that differences can be attributed to the group processes present in the gang setting. This study explores the extent to which differences between youth in a gang and those in a delinquent group can be explained by Bandura’s social cognitive theory. Much of the prior research in this arena has relied on cross-sectional data; in this study, we expand on this prior research using fixed-effects modeling strategies with a multi-site panel of youth. The results comparing time periods when youth were in a gang versus a delinquent peer group indicate that gang-involved youth are more violent and have fewer conventional bonds. This work is able to advance our knowledge on attitudinal and behavioral differences between gangs and other types of peer groups
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