Allelopathic effects of Rumex obtusifolius leaf extracts against native grassland species

In perennial grasslands R. obtusifolius (broad-leaved dock) is often surrounded by certain plant species. Thus, it is hypothesized for the current study that Rumex can affect their neighbouring plant species by allelopathic interactions. To test this hypothesis, in a series of laboratory and field experiments aqueous extracts of green R. obtusifolius leaves were sprayed on seeds of 14 herbaceous plant species (graminoids, non-leguminuous forbs and leguminuous forbs) commonly native to perennial grasslands and its effects on seed germination compared with those with tap water spraying. An allelopathic effect was defined as inhibitory influence of Rumex extracts on seed germination relative to tap water. Generally, results of the laboratory experiments showed a species-specific susceptibility of grassland species to Rumex extracts; no species was promoted by Rumex extracts. All grasses tested were heavily inhibited by Rumex extracts, herbs and legumes varied from not affected until heavily inhibited. Spraying of Rumex extracts in the field had no effect on germination of these species. The results could be considered in designing seeding mixtures for resowing sward damages to especially contain species not susceptible to Rumex allelopathy (e.g. Trifolium pratense, T. repens, Plantago lanceolata) that would thus be assumed to be more competitive against R. obtusifolius regrowing in these grasslands

LOX/Hydrogen Coaxial Injector Atomization Test Program

Quantitative information about the atomization of injector sprays is needed to improve the accuracy of computational models that predict the performance and stability margin of liquid propellant rocket engines. To obtain this data, a facility for the study of spray atomization is being established at NASA-Lewis to determine the drop size and velocity distributions occurring in vaporizing liquid sprays at supercritical pressures. Hardware configuration and test conditions are selected to make the cold flow simulant testing correspond as closely as possible to conditions in liquid oxygen (LOX)/gaseous H2 rocket engines. Drop size correlations from the literature, developed for liquid/gas coaxial injector geometries, are used to make drop size predictions for LOX/H2 coaxial injectors. The mean drop size predictions for a single element coaxial injector range from 0.1 to 2000 microns, emphasizing the need for additional studies of the atomization process in LOX/H2 engines. Selection of cold flow simulants, measured techniques, and hardware for LOX/H2 atomization simulations are discussed

Coaxial injector spray characterization using water/air as simulants

Quantitative information about the atomization of injector sprays is required to improve the accuracy of computational models that predict the performance and stability of liquid propellant rocket engines. An experimental program is being conducted at NASA-Lewis to measure the drop size and velocity distributions in shear coaxial injector sprays. A phase/Doppler interferometer is used to obtain drop size data in water air shear coaxial injector sprays. Droplet sizes and axial component of droplet velocities are measured at different radii for various combinations of water flow rate, air flow rate, injector liquid jet diameter, injector annular gap, and liquid post recess. Sauter mean diameters measured in the spray center 51 mm downstream of the liquid post tip range from 28 to 68 microns, and mean axial drop velocities at the same location range from 37 to 120 m/s. The shear coaxial injector sprays show a high degree of symmetry; the mean drop size and velocity profiles vary with liquid flow rate, post recess, and distance from the injector face. The drop size data can be used to estimate liquid oxygen/hydrogen spray drop sizes by correcting property differences between water-air and liquid oxygen/hydrogen

How expanding Medicaid can help prisoners in the Southern states.

While the Obama presidency saw the introduction of Obamacare and the expansion of Medicaid in many US states, President Trump’s administration may well roll back these reforms. Nickolas Zaller argues that while they can, Southern states should expand Medicaid, one effect of which would be to improve health outcomes for those involved with the criminal justice system. He suggests that in order to expand Medicaid, these states should focus on incremental change, re-brand Medicaid as a state led initiative, and link it to criminal justice reform

Der Einfluss von Feld- und Landschaftsparameter auf die Abundanzen wichtiger Rapsschädlinge

In agroecological research it has been appreciated only fairly recently that plant-insect interactions and other ecological processes depend on scales much larger than a single habitat (Wiens et al. 1997). Crop-pest interactions have mainly been studied on single pest species by focusing either on the impact of field parameters or on landscape structure but only rarely included both factors (Östman et al. 2001). Here we investigated how the abundances of three major insect pest species in oilseed rape (OSR) responded to field parameters and landscape characteristics at various spatial scales. Pest species considered in the current study include (i) ceutorhynchid stem weevils that lay eggs in leaf petioles or midribs of OSR plants while the larvae tunnel in the stems; (ii) pollen beetles that feed on pollen and destroy flower buds and (iii) brassica pod midge that lay eggs into OSR pods where the hatched larvae consume the seeds as well as tissue of the pod walls and cause the pods to split prematurely (Alford et al. 2003). Studying these different groups of pests is especially important because they attack different parts of the crop, use different habitats as overwintering sites and also differ in their mobility; with the exception of pollen beetles these pest species have never been studied in a landscape context. The specific objectives of this study were to determine (i) whether the major OSR pest species differ in their relation to field and landscape characteristics and (ii) at which spatial scales landscape variables are effective.Der Einfluss von Feld- und Landschaftsparameter auf die Abundanzen wichtiger Rapsschädlinge (Rapsglanzkäfer - Meligethes aeneus und M. viridescens, Nitidulidae, Coleoptera; Gefleckter Kohltriebrüssler und Großer Rapsstängelrüssler - Ceutorhynchus pallidactylus und C. napi, Curculionidae, Coleoptera; Kohlschotenmücke - Dasineura brassicae, Cecidomyiidae, Diptera) wurde untersucht. In Raps-Untersuchungsfeldern wurden die Beziehungen zwischen Schädlingsabundanzen und Feld-/Landschaftsparametern in 29 von strukturarm bis komplex reichenden Landschaftssektoren auf acht räumlichen Skalen (Radien 250 - 2000 m) untersucht. Die Abundanzen der Stängelrüssler waren signifikant positiv korreliert mit der Bestandesdichte des Raps und der Bodenqualität. Die Abundanzen der Rapsglanzkäfer reagierten auf allen Radien signifikant negativ mit dem Anteil an Rapsfläche und positiv mit der Bestandesdichte. Die Dichte der Kohlschotenmücke war jeweils auf dem kleinsten Radius signifikant positiv mit dem Anteil an Gehölzen korreliert, negativ mit dem Anteil an Rapsfläch

Prevention and treatment of murine experimental allergic encephalomyelitis with T cell receptor Vβ-specific antibodies

Experimental allergic encephalomyelitis (EAE) is a model system for T cell-mediated autoimmune disease. Symptoms of EAE are similar to those of multiple sclerosis (MS) in humans. EAE is induced in susceptible animal strains by immunization with myelin basic protein (MBP) and potent adjuvant. The major T cell response to MBP in B10.PL mice is directed towards an NH2-terminal epitope and involves T cells expressing either V beta 8.2 or V beta 13 gene segments. Animals treated with a TCR V beta 8-specific mAb have a reduced incidence of EAE. We report here that the in vivo administration of a combination of anti-V beta 8.2 and anti-V beta 13 mAbs results in a long-term elimination of T cells involved in the response to MBP. When given before MBP immunization, anti-TCR antibody treatment leads to nearly complete protection against EAE. Antibody treatment also results in a dramatic reversal of paralysis in diseased animals. Thus, treatment with a combination of V beta-specific antibodies is a very effective therapy for the prevention and treatment of EAE. It is hoped that the future characterization of TCR V gene usage in human autoimmune diseases may lead to similar strategies of immune intervention

Skalenabhängiger Einfluss der Landschaft auf die Diversität epigäischer Spinnen in Winterrapsfeldern

Agricultural intensification is a major threat to biological diversity worldwide. Land management activities enhancing landscape diversity are therefore regarded as a key strategy to halt species loss in cultural landscapes. Diverse and abundant communities of predatory arthropods, e.g. spiders (Araneae), have a high potential to suppress pest populations (Symondson et al. 2002) and could therefore contribute to allow reductions of pesticide use. Crop fields alone are usually not able to sustain diverse and individual-rich populations of predatory arthropods, because agricultural management results in disturbances and habitat deteriorations (harvest, soil cultivation, pesticide application) that kill or drive away large parts of the populations. Therefore semi-natural and perennial habitats in agricultural landscapes are considered to be of great importance for beneficial arthropods. On the one hand they offer refuge habitats in times when arable fields are hostile, e.g. fields with bare grounds during winter (Schmidt & Tscharntke 2005). On the other hand, viable populations of predatory arthropods in semi-natural habitats can serve as sources for (re-) colonisation of arable fields (Schmidt & Tscharntke 2005). Because of these exchanges between crop and non-crop areas it is important to include the surrounding landscape when investigating field-scale processes. We investigated the relations between spider assemblages in arable fields and the surrounding landscape in 29 fields of winter oilseed rape (OSR) in an agricultural landscape in eastern Austria. The objectives of this study were to estimate (1) how much spider assemblages in oilseed rape fields are influenced by the surrounding landscape, (2) the relative influence of landscape variables compared to field-scale variables and (3) at which spatial scales landscape variables are effective.Die Intensivierung der Landwirtschaft stellt weltweit eine der bedeutendsten Bedrohungen der Biodiversität dar. Maßnahmen, die die Diversität der Landschaft erhöhen werden daher als eine zentrale Möglichkeit gesehen, den Verlust von Arten in Kulturlandschaften zu stoppen und durch die Förderung von Nützlingen einen Betrag zu einer Reduktion des Pestizideinsatzes zu leisten. Wir untersuchten den Einfluss der Landschaft auf epigäische Spinnen (Araneae) in 29 Winterrapsfelder in einer durch landwirtschaftliche Nutzung dominierten Region östlich von Wien (Österreich). Spinnen – generalistische Prädatoren, die ein bedeutsames Potenzial in der natürlichen Schädlingskontrolle aufweisen – wurden während der Feldsaison 2005 mit Barberfallen erfasst. Die umgebenden Landschaften wurden hinsichtlich Zusammensetzung, Diversität und Komplexität charakterisiert (Landschaftsausschnitte mit 250 bis 2000 m Radius). Zusätzlich wurden Feldparameter, vor allem die Bewirtschaftung betreffend, in die Analyse einbezogen. Die Datenanalyse erfolgte mit Generalized Linear Models. Unsere Ergebnisse zeigten, dass die Spinnengemeinschaften hinsichtlich Diversität und Individuenzahlen auf unterschiedliche Landschaftvariablen auf unterschiedlichen Skalenebenen reagieren. Für die Gesamtartenzahl war der Anteil an gehölzdominierten Habitaten in der näheren Umgebung der Felder der wichtigste, fördernde Faktor. Die Anzahl der häufigen Arten und die Gesamtindividuenzahlen hingegen nahmen mit dem Anteil an Brachen bzw. der Lauflänge an Wegrainen in größerem Umkreis der Felder zu. Diese Ergebnisse unterstreichen die Bedeutung von naturnahe Landschaftselementen, v.a. Brachen, für epigäische Spinnen als eine Gruppe von räuberischen Arthropoden in Agrarsystemen

Opinion polarization in the Receipt-Accept-Sample model

The Zaller theory of opinion formation is reformulated with one free parameter $\mu$, which measures the largest possible ideological distance which can be made by a citizen in one mental step. Our numerical results show the transient effects: {\it i)} the political awareness, measured by the number of received messages, increases with time first exponentially, later linearly; {\it ii)} for small $\mu$ correlations are present between previously and newly received messages; {\it iii)} these correlation lead to a hyperdiffusion effect in the space of attitudes of messages. Citizens with small $\mu$ are more prone to extremal opinions.Comment: 13 pages, 6 figures; text improved, thanks to Referee

Soil sand content can alter effects of different taxa of mycorrhizal fungi on plant biomass production of grassland species

AbstractIn this greenhouse experiment we tested whether (i) ubiquitous arbuscular mycorrhizal fungi (AMF) taxa (Glomus claroideum, Glomus geosporum, Glomus intraradices, Glomus mosseae) singly and in a mixture differently affect growth and biomass production of four co-occurring grassland species (grass: Arrhenatherum elatius, non-leguminous forbs: Plantago lanceolata, Salvia pratensis and leguminous forb Trifolium pratense), and (ii) different soil sand contents alter AMF influence. We hypothesized that AMF effects on plants will increase with an increased AMF diversity and with increasing sand content. Percent AMF colonization of roots differed between plant species and AMF taxa and was higher with higher sand content. Plant growth responses to AMF were species-specific both regarding plants and AMF. Generally, biomass production of the non-leguminous forbs was the most responsive, the grass species the least and the legume intermediate both for AMF treatments and sand content. Across species, AMF influence on plant biomass increased with increasing soil sand content. Plant species growing in soil containing a mix of four AMF taxa showed similar growth responses than species in soil containing only one AMF taxon. These results suggest that both interference among AMF taxa and soil sand content can trigger the influence of AMF on plant production in grassland species