2,058 research outputs found

    Comparative Study of \u3ci\u3eMecinus Janthiniformis\u3c/i\u3e (Coleoptera: Curculionidae) Attack and Simulated Mowing for Control of \u3ci\u3eLinaria Dalmatica\u3c/i\u3e Spp. \u3ci\u3eDalmatica\u3c/i\u3e (Plantaginaceae)

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    Dalmatian toadflax, Linaria dalmatica spp. dalmatica (L.) Mill. (Plantaginaceae) has invaded over one million hectares in the western United States and Canada, in habitats similar to its native range. Two field studies were conducted to examine the impact of simulated mowing or insect herbivory on L. dalmatica growth and reproduction. Simulated mowing over the duration of the study decreased L. dalmatica total biomass per square meter, significantly reduced the total number of fruits and flowers per square meter, and resulted in significantly shorter flowering stems in the simulated mowing plots than in their controls. Plants in plots attacked by Mecinus janthiniformis Toševski and Caldara (Coleoptera: Curculionidae) had significantly less biomass per square meter, significantly fewer total numbers of fruits and flowers per square meter, and significantly fewer reproductive structures per stem than plants in paired control plots over the duration of the study. Specifically, both management tactics resulted in a negative impact on this invasive plant. With repeated tissue removal or damage, a reduction in numbers of fruits and flowers per stem on both the stems subjected to simulated mowing and Mecinus-attacked stems relative to their controls suggests that long term stress effects on the plants may be similar. The results of these studies suggest that mowing may warrant further evaluation as a possible method of control in areas where M. janthiniformis release is not effective

    Impact of \u3ci\u3eMecinus Janthinus\u3c/i\u3e (Coleoptera: Curculionidae) on the Growth and Reproduction of \u3ci\u3eLinaria Dalmatica\u3c/i\u3e (Scrophulariaceae)

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    Dalmatian toadflax, Linaria dalmatica (L.) Mill. (Scrophulariaceae), a native to the eastern Mediterranean and Black Sea regions of Europe and Asia, has invaded over one million hectares in the western United States and Canada, in habitats similar to its native range. Once established, the aggressive vegetative growth of the plant allows it to invade undisturbed habitats where it can out-compete most other vegetation, placing native plant communities at risk. Biological control of L. dalmatica with Mecinus janthinus Thomson (Coleoptera: Curculionidae) has shown promise in the field. In both studies reported in this paper, the presence of insect attack reduced L. dalmatica plant growth and reduced plant reproductive potential. In a field sleeve cage study, insect- attacked stems were significantly shorter (18 cm) and had 50-70% fewer fruits and flowers than the control stems at the end of the study period. M. janthinus attacked stems showed little apical growth, fewer fruits and flowers, and lower stem biomass relative to control stems. Similar results were observed in the potted plant study where the influence of the extensive root system of the plant was eliminated. This negative impact by the insect is caused both by adult feeding in the apical portion of the plant and the physical destruction of the plant stem from larvae feeding. The decrease in the insect-attacked stem heights may also have an impact on seed dispersal from the mature reproductive structures. A combination of decreased seed production through M. janthinus biological control and poor seedling competition in the moisture limited sites common to north-central Washington State and other similarly dry habitats may negatively influence L. dalmatica populations more than general models predict

    Is Propranolol Administration Following a Traumatic Event Effective in Reducing Symptoms of Post-Traumatic Stress Disorder?

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    OBJECTIVE: The objective of this selective EBM review is to determine whether or not propranolol administration following a traumatic event is effective in reducing symptoms of post-traumatic stress disorder (PTSD). STUDY DESIGN: Review of three English language randomized, double-blind, placebo-controlled clinical trials published in 2002, 2007, and 2010. DATA SOURCES: Three randomized, double-blind, placebo-controlled clinical trials found using PubMed and Cochrane Library databases. OUTCOMES MEASURED: The incidence of PTSD symptoms was measured in patients following traumatic events after the administration of propranolol. This was done using The Screening Tool for Early Predictors of PTSD, the Clinician Administered PTSD Scale for Children and Adolescents, the Clinician Administered PTSD Scale (CAPS), Script-driven Imagery, The Acute Stress Disorder Scale, the CIDI Modules for PTSD, MDD, and panic disorder, the DSM-IV, and The Posttraumatic Stress Disorder Checklist. RESULTS: Three randomized, double-blind, placebo-controlled studies comparing propranolol to placebo were reviewed. The Nugent study demonstrated a clinical benefit of propranolol vs. placebo in PTSD symptoms in a pediatric sample. The Pitman study showed inconclusive results for using propranolol over placebo in incidence of PTSD symptoms in an adult sample. The Stein study did not show a difference in incidence of PTSD symptoms in propranolol vs. placebo in an adult sample. CONCLUSION: While it remains inconclusive at this time as to the benefit of propranolol in reducing PTSD symptoms, two of the trials support the clinical feasibility of this hypothesis. Further studies are warranted to investigate the relationship between propranolol administration and the development of PTSD symptomatology

    Investment Behavior and the Small Firm Effect

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    Our purpose in this review is to develop one explanation of market behavior which is consistent with the many empirical findings that appear to be inconsistent with the market efficiency hypothesis. To date, researchers have attempted to reconcile their empirical results with market efficiency based on either measurement error or structural inefficiencies. We propose a different approach to market efficiency. We posit that the empirical findings previous researchers report are by their nature ex post, and are a direct result of a market which is best described as efficient. We develop a model and provide a simulation to support this explanation

    Comprehensive structural model of the mechanochemical cycle of a mitotic motor highlights molecular adaptations in the kinesin family

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    Kinesins are responsible for a wide variety of microtubule-based, ATP-dependent functions. Their motor domain drives these activities but the molecular adaptations that specify these diverse and essential cellular activities are poorly understood. It has been assumed that the first identified kinesin - the transport motor kinesin-1 – is the mechanistic paradigm for the entire superfamily, but accumulating evidence suggests that this is not the case. To address the deficits in our understanding of the molecular basis of functional divergence within the kinesin superfamily, we studied kinesin-5s, which are essential mitotic motors whose inhibition blocks cell division. Using cryo-electron microscopy and subnanometer resolution structure determination, we have visualised conformations of microtubule-bound human kinesin-5 motor domain at successive steps in its ATPase cycle. Following ATP hydrolysis, nucleotide-dependent conformational changes in the active site are allosterically propagated into rotations of the motor domain and uncurling of the drugbinding loop L5. In addition, the mechanical neck-linker element that is crucial for motor stepping undergoes discrete, ordered displacements. We also observed large reorientations of the motor N-terminus that indicate its importance for kinesin-5 function through control of neck-linker conformation. A kinesin-5 mutant lacking this N-terminus is enzymatically active, and ATP-dependent neck-linker movement and motility is defective although not ablated. All these aspects of kinesin-5 mechanochemistry are distinct from kinesin-1. Our findings directly demonstrate the regulatory role of the kinesin-5 N-terminus in collaboration with the motor’s structured neck-linker, and highlight the multiple adaptations within kinesin motor domains that tune their mechanochemistries according to distinct functional requirements

    Comparative Study of \u3ci\u3eMecinus Janthiniformis\u3c/i\u3e (Coleoptera: Curculionidae) Attack and Simulated Mowing for Control of \u3ci\u3eLinaria Dalmatica\u3c/i\u3e Spp. \u3ci\u3eDalmatica\u3c/i\u3e (Plantaginaceae)

    Get PDF
    Dalmatian toadflax, Linaria dalmatica spp. dalmatica (L.) Mill. (Plantaginaceae) has invaded over one million hectares in the western United States and Canada, in habitats similar to its native range. Two field studies were conducted to examine the impact of simulated mowing or insect herbivory on L. dalmatica growth and reproduction. Simulated mowing over the duration of the study decreased L. dalmatica total biomass per square meter, significantly reduced the total number of fruits and flowers per square meter, and resulted in significantly shorter flowering stems in the simulated mowing plots than in their controls. Plants in plots attacked by Mecinus janthiniformis Toševski and Caldara (Coleoptera: Curculionidae) had significantly less biomass per square meter, significantly fewer total numbers of fruits and flowers per square meter, and significantly fewer reproductive structures per stem than plants in paired control plots over the duration of the study. Specifically, both management tactics resulted in a negative impact on this invasive plant. With repeated tissue removal or damage, a reduction in numbers of fruits and flowers per stem on both the stems subjected to simulated mowing and Mecinus-attacked stems relative to their controls suggests that long term stress effects on the plants may be similar. The results of these studies suggest that mowing may warrant further evaluation as a possible method of control in areas where M. janthiniformis release is not effective

    Évaluation d'un système de mesure des pertes de contaminants agricoles par ruissellement et drainage souterrain en régions froides

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    Cette note technique présente un système automatique de mesure des pertes de polluants agricoles par ruissellement et drainage souterrain pouvant opérer durant la période estivale et la fonte nivale. Le système de mesure du ruissellement est composé d'une trappe à sédiments, d'un déversoir en V et d'un système automatique de mesure du débit et de contrôle de l'échantillonnage. Le système de mesure du drainage souterrain consiste en un auget à bascule, relié à un compteur d'impulsions, et un partiteur de débit. Ces systèmes ont été utilisés sur neuf parcelles expérimentales pour mesurer les masses de contaminants agricoles perdues par ruissellement et drainage souterrain. La hauteur totale de ruissellement durant les deux années (4,6 mm an-1) a été faible comparée au drainage (227 mm an-1). Soixante-seize pourcent du ruissellement annuel s'est produit durant la fonte des neiges. Les principaux avantages de ce système sont de pouvoir mesurer simultanément les volumes et les débits de ruissellement tout en prélevant des échantillons d'eau.This technical note presents an automatic measurement system for measuring losses of agricultural pollutants in surface runoff and subsurface drainage outflow. This system can be operated during rainfall events and snowmelt periods. The runoff system was composed of a sediment trap, a V-notch weir and an automatic system for flow measurement and sampling. The subsurface drainage system consisted of a tipping bucket, connected to a pulse counter, and a sampling unit. This system was used on nine experimental plots for the measurement of pollutant losses by surface runoff and subsurface drainage. The total depth of surface runoff measured was low for the two years of measurement (4.6 mm y-1) compared to subsurface drainage (227 mm y-1). Seventy six percent of the annual surface runoff occurred during the snowmelt period. The principal advantage of this system is to measure runoff volume and flow while taking water samples

    Supramolecular hierarchy among halogen and hydrogen bond donors in light-induced surface patterning

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    Halogen bonding, a noncovalent interaction possessing several unique features compared to the more familiar hydrogen bonding, is emerging as a powerful tool in functional materials design. Herein, we unambiguously show that one of these characteristic features, namely high directionality, renders halogen bonding the interaction of choice when developing azobenzene-containing supramolecular polymers for light-induced surface patterning. The study is conducted by using an extensive library of azobenzene molecules that differ only in terms of the bond-donor unit. We introduce a new tetrafluorophenol-containing azobenzene photoswitch capable of forming strong hydrogen bonds, and show that an iodoethynyl-containing azobenzene comes out on top of the supramolecular hierarchy to provide unprecedented photoinduced surface patterning efficiency. Specifically, the iodoethynyl motif seems highly promising in future development of polymeric optical and photoactive materials driven by halogen bonding

    Portrait de la situation en matière de recherche scientifique pour l’économie sociale du Canada

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    Ce rapport présente les premiers résultats d’une veille sur la recherche scientifique en économie sociale au Canada. Nous y avons répertorié divers organismes de recherche qui traitent de l’économie sociale et coopérative. Les critères de sélection étant la scientificité de la production et son importance en volume, nous avons pu répertorier près de vingt-cinq organismes. Toutefois, cette recherche n’est pas exhaustive puisque nous n’avons pas procédé à une enquête systématique de tous les organismes de recherche sur le sujet au Canada. Trois types d’organismes de recherche y ont été répertoriés soit, les centres universitaires ; les associations scientifiques, partenariales et sectorielles ; les organismes gouvernementaux. Chaque organisme est classé sous forme de fiche qui comprend ses coordonnées, une courte présentation, les thématiques qui y sont traitées, les types de publications et les sources de financement. Ce rapport est le deuxième de sa série. Le premier a été publié en mars 2005 (Cahier R-2005-03).This report presents a first outlook of the scientific research on the social economy in Canada. We list diverse research organizations that work on the social and co-operative economy. Selection criteria being the scientific aspect of the production and the importance of it in terms of volume, we have been able to identify almost twenty-five organizations. Nevertheless, this research is not exhaustive, since we have not gone through with a systematic enquiry of all the research organizations working on the social economy in Canada. Three types of research organizations have been listed: university centres; scientific, partnership and sector associations; government organizations. Each organization is classified as a record that includes the mail and electronic addresses, a short presentation, the themes that are developed, the types of publications and the financing sources. This report is the second of its series. The first one was published in March, 2005 (Working Paper R-2005-03)
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