Distribution by Scientific Domains
Distribution within Life Sciences

Kinds of Plots

  • Arrheniu plot
  • altman plot
  • bland-altman plot
  • circular plot
  • contour plot
  • control plot
  • diagnostic plot
  • different plot
  • dixon plot
  • experimental plot
  • fertilized plot
  • field plot
  • forest plot
  • funnel plot
  • garden plot
  • grassland plot
  • hammett plot
  • inventory plot
  • kaplan-meier plot
  • linear plot
  • m plot
  • meier plot
  • monoculture plot
  • nyquist plot
  • one plot
  • paired plot
  • permanent plot
  • probability plot
  • ramachandran plot
  • removal plot
  • replicated plot
  • runoff plot
  • same plot
  • sample plot
  • sampling plot
  • scatchard plot
  • small plot
  • study plot
  • surface plot
  • treatment plot
  • unfertilized plot
  • vegetation plot

  • Terms modified by Plots

  • plot analysis
  • plot data
  • plot design
  • plot distributed
  • plot experiment
  • plot scale
  • plot treatment

  • Selected Abstracts


    D. R. Edwards
    ABSTRACT: Grazed pastures represent a potential source of non-point pollution. In comparison to other nonpoint sources (e.g., row-cropped lands), relatively little information exists regarding possible magnitudes of pollution from grazed pasture; how that pollution is affected by weather, soil, management and other variables; and how the pollution can be minimized. The objective of this study was to assess how the quality of runoff from fescue plots is influenced by duration of cattle manure application (4,12 weeks) and manure application strategy (none, weekly application of 1.4 kg/plot, and monthly application at 5.6 kg/plot). Additional analyses were performed to relate runoff quality to the timing of sample collection. The study was conducted at the University of Kentucky Maine Chance Agricultural Experiment Station north of Lexington. Plots (2.4 m wide by 6.1 m long) were constructed and established in Kentucky 31 fescue (Festuca arundinacea Schreb.) to represent pasture. Grazing was simulated by application of beef cattle manure to the plots. Runoff was generated by applying simulated rainfall approximately 4, S and 12 weeks following initiation of manure application. Runoff samples were collected and analyzed according to standard methods for nitrogen (N), phosphorus (P) and fecal coliforms (FC). Runoff concentrations of N and P from manure-treated plots were low and generally not consistently different from control plot concentrations or related to manure application strategy. Runoff FC concentrations from manure-treated plots were higher than from control plot concentrations. Runoff concentrations of ammonia N, total Kjeldahl N, ortho-P and FC decreased approximately exponentially in response to increasing time of sample collection. These findings suggest that manure deposition on well-managed pasture at the rates used in this study might have a negligible impact on nutrient content of runoff. [source]

    Henry Neville and the toleration of Catholics during the Exclusion Crisis

    HISTORICAL RESEARCH, Issue 222 2010
    Gaby Mahlberg
    While the Popish Plot of the later seventeenth century is commonly seen as a fabrication by the political opposition employed to root out Catholicism and secure a Protestant succession in England, this article shows that there were also voices within the opposition that exposed the scapegoating of Catholics as a political ploy, backed the succession of the duke of York and even argued for a toleration of Catholics. Using the example of the republican Henry Neville, his political writings and correspondence with Cosimo III, this article calls for a reassessment of the political and religious divisions of the so-called Exclusion Crisis. [source]

    Changes in hydrology and erosion over a transition from grassland to shrubland

    Laura Turnbull
    Abstract The degradation of grasslands is a common problem across semi-arid areas worldwide. Over the last 150 years, much of the south-western United States has experienced significant land degradation, with desert grasslands becoming dominated by shrubs and concurrent changes in runoff and erosion which are thought to propagate further the process of degradation. Plot-based experiments to determine how spatio-temporal characteristics of soil moisture, runoff and erosion change over a transition from grassland to shrubland were carried out at four sites over a transition from black grama (Bouteloua eriopoda) grassland to creosotebush (Larrea tridentata) shrubland at the Sevilleta NWR LTER site in New Mexico. Each site consisted of a 10 × 30 m bounded runoff plot and adjacent characterization plots with nested sampling points where soil moisture content was measured. Results show distinct spatio-temporal variations in soil moisture content, which are due to the net effect of processes operating at multiple spatial and temporal scales, such as plant uptake of water at local scales versus the redistribution of water during runoff events at the hillslope scale. There is an overall increase in runoff and erosion over the transition from grassland to shrubland, which is likely to be associated with an increase in connectivity of bare, runoff-generating areas, although these increases do not appear to follow a linear trajectory. Erosion rates increased over the transition from grassland to shrubland, likely related in part to changes in runoff characteristics and the increased capacity of the runoff to detach, entrain and transport sediment. Over all plots, fine material was preferentially eroded which has potential implications for nutrient cycling since nutrients tend to be associated with fine sediment. Copyright © 2009 John Wiley & Sons, Ltd. [source]

    Johansson revisited: the spatial structure of epiphyte assemblages

    Gerhard Zotz
    Abstract Question: Vertical zonation schemes are widely used in biodiversity studies with vascular epiphytes as a tool to capture spatial distribution patterns, the one most commonly used was proposed by Johansson more than 30 years ago. Does a survey of the epiphytes found on larger trees really yield a representative sample of the local community? Location: Lowland rainforest of the San Lorenzo Crane Plot, Republic of Panama. Methods: A complete census of the vascular epiphytes on all trees > 1 cm DBH in 0.4 ha of undisturbed lowland forest was analysed with both cluster and discriminant analysis to detect groupings of epiphyte species. Results: Six different groups of species were detected, five of them preferring different substrates on larger trees (as defined by (1) the height above ground at the attachment site, (2) the diameter of the substrate and (3) the occurrence on stem vs branches/twigs) and resembling to some extent the original Johansson zones. A sixth group of epiphytes, comprising ca. 10% of all taxa, was almost always found on small diameter stems and branches of trees with small DBH at lower and intermediate heights within the forest. Conclusions: Applying pre-established zonation schemes may lead to misleading results in biodiversity studies with epiphytes. Important aspects of spatial distribution patterns may be missed, and the determination of relative species abundances may carry a strong quantitative and qualitative bias when analyses rely completely on epiphytic plants found on larger trees. [source]

    The Melbourne Jewish Left, Communism and the Cold War.

    Responses to Stalinist Anti-Semitism, the Rosenberg Spy Trial
    This article explores the political marginalisation of the Melbourne Jewish Council to Combat Fascism and Anti-Semitism during the Cold War. Attention is drawn to contending views about the nature of the Council's links with communism. By comparing the Council's response to two coinciding international events during 1952 and 1953 - the anti-Jewish show trials in Stalinist Eastern Europe, and the Rosenberg spy trial in the USA - evidence is derived confirming the dominance of communist influence within the Jewish Council at that time. In order, I examine the Australian Jewish political context in which the Council operated and its relations with the wider Jewish community prior to the Cold War; explore rival arguments concerning the Council's links with communism and the Australian Communist Party; examine the major features of Stalinist anti-Semitism and the Council's response to them; recount the Council's reaction to the Rosenberg Spy Trial and Doctors Plot; and conclude that the Council lost influence because it fell under the control of a pro-Soviet group unwilling to recognise and attack anti-Semitism on the political left. [source]

    Spatial Distribution of Vascular Epiphytes (including Hemiepiphytes) in a Lowland Amazonian Rain Forest (Surumoni Crane Plot) of Southern Venezuela,

    BIOTROPICA, Issue 3 2000
    Jürgen Nieder
    ABSTRACT The mobile crane of the Surumoni project allowed for the first time ever a complete inventory and spatial description of the epiphytic vegetation of a tropical lowland rain forest plot (1.5 ha), at La Esmeralda on the upper Orinoco River, Venezuela. A total of 778 individual vascular epiphytes of 53 species was found, dominated by 19 orchid species and 14 species of Araceae. Fifty percent of all individual plants were obligate ant-garden epiphytes. The distribution of epiphytes was highly clumped and not random. The clumped occurrence of holoepiphytes (complete life cycle on host tree) was the consequence of the rarity of suitable phorophytes (host trees; e.g., size and age) in the plot and the preference of ants for gaps where most of the ant-garden epiphytes were found. In comparison, hemiepiphytes were distributed more evenly because of greater independence from tree suitability. The dispersal modes of epiphytes did not explain their distribution patterns. There was no consistent difference in distribution between anemochorous and zoochorous epiphytes, presumably because availability of suitable substrate is the more important factor for epiphyte establishment and growth. Whereas the vertical distribution of epiphytes could be attributed largely to deterministic factors such as physiological adaptation and requirements, horizontal distribution appeared to be governed by suitable substrate, which in turn seemed to be governed by stochastic gap formation. RESUMEN En el context0 del proyecto Surumoni se hizo un inventario y un analisis espacial de la vegetación epifitica de un plot de 1.5 ha en el alto rio Orinoco cerca de La Esmeralda (Venezuela) en 1997. Consiste de 778 plantas individuales de 53 especies, entre las cuales destacan las orquideas (19 especies) y las aráceas (14 especies). El 50 porciento de todas las epifitas se encuentran en los jardines epifiticas de hormigas. Las plantas epifiticas muestran una distribución aglomerada y no casual. En el caso de las holoepifitas esto es la consecuencia de la raridad de forófitas aduecadas (p.e., altura y edad) en el plot y la preferencia de claros ("gaps") por parte de las hormigas. En comparación, tienen una distribución más homogénea las hemi-epifitas porque se desarrollan más independientemente de la calidad de sus forofitas. Las estrategias de dispersión de las epifitas sólo en parte explica sus patrones de distribución. No hay diferencias consistentes entre especies anemocorias y zoocorias, probablemente porque la disponibilidad de sustrato adecuado es el factor más importante para el establecimiento y desarrollo de epifitas. La distribución vertical de las epifitas se caracteriza por una zonación marcada, visible en las diferencias significantes entre la rnayoria de las taxas epifiticas. Mientras que se puede atribuir la distribución vertical a factores deterministicos como adaptaciones y exigencias fisiológicos de las plantas epifiticas, su distribución horizontal se arregla según la presencia de sustrato adecuado, que por su parte es resultado de factores estoquáticos en la formación de claros. [source]

    Numerical simulation of the inception of channel meandering

    Jennifer G. Duan
    Abstract The inception of channel meandering is the result of the complex interaction between flow, bed sediment, and bank material. A depth-averaged two-dimensional hydrodynamic model is developed to simulate the inception and development of channel meandering processes. The sediment transport model calculates both bedload and suspended load assuming equilibrium sediment transport. Bank erosion consists of two interactive processes: basal erosion and bank failure. Basal erosion is calculated from a newly derived equation for the entrainment of sediment particles by hydrodynamic forces. The mass conservation equation, where basal erosion and bank failure are considered source terms, was solved to obtain the rate of bank erosion. The parallel bank failure model was tested with the laboratory experiments of Friedkin on the initiation and evolution processes of non-cohesive meandering channels. The model replicates the downstream translation and lateral extension of meandering loops reasonably well. Plots of meandering planforms illustrate the evolution of sand bars and redistribution of flow momentum in meandering channels. This numerical modelling study demonstrates the potential of depth-integrated two-dimensional models for the simulation of meandering processes. Copyright © 2005 John Wiley & Sons, Ltd. [source]

    Geostatistical analysis of ground-survey elevation data to elucidate spatial and temporal river channel change

    Adrian Chappell
    Abstract A digital elevation model (DEM) of a fluvial environment represented landform surface variability well and provided a medium for monitoring morphological change over time. Elevation was measured above an arbitrary datum using a ground-based three-dimensional tacheometric survey in two reaches of the River Nent, UK, in July 1998, October 1998 (after flood conditions) and June 1999. A detailed geostatistical analysis of the elevation data was used to model the spatial variation of elevation and to produce DEMs in each reach and for each survey period. Maps of the difference in elevation were produced and volumetric change was calculated for each reach and each survey period. The parameters of variogram models were used to describe the morphological character of each reach and to elucidate the linkages between process and the form of channel change operating at different spatial and temporal scales. The analysis of channel change on the River Nent shows the potential of geostatistics for investigating the magnitude and frequency of geomorphic work in other rivers. A flood modified the channel features, but low magnitude and high frequency flows rationalized the morphology. In spite of relatively small amounts of net flux the channel features changed as a consequence of the reworking of existing material. The blocking of chute entrances and redirection of the channel had a considerable effect on the behaviour of the channel. Such small changes suggested that the distributary system was sensitive to variation in sediment regime. Plots of the kriging variances against sampling intervals were used to quantify the temporal variation in sampling redundancy (ranging between ,11 per cent and +93 per cent). These curves illustrated the importance of bespoke sampling designs to reduce sampling effort by incorporating anisotropic variation in space and geomorphic information on flow regime. Variation in the nugget parameter of the variogram models was interpreted as sampling inaccuracy caused by variability in particle size and is believed to be important for future work on surface roughness. Copyright © 2003 John Wiley & Sons, Ltd. [source]

    Using measured octanol-air partition coefficients to explain environmental partitioning of organochlorine pesticides

    Mahiba Shoeib
    Abstract Octanol-air partition coefficients (Koa) were measured directly for 19 organochlorine (OC) pesticides over the temperature range of 5 to 35°C. Values of log Koa at 25°C ranged over three orders of magnitude, from 7.4 for hexachlorobenzene to 10.1 for 1,1-dichloro-2,2-bis (p-chlorophenyl) ethane. Measured values were compared to values calculated as KowRT/H (where R is the ideal gas constant [8.314 J mol,1 K,1], T is absolute temperature, and H is Henry's law constant) were, in general, larger. Discrepancies of up to three orders of magnitude were observed, highlighting the need for direct measurements of Koa. Plots of Koa versus inverse absolute temperature exhibited a log-linear correlation. Enthalpies of phase transition between octanol and air (,Hoa) were determined from the temperature slopes and were in the range of 56 to 105 kJ mol,1 K,1. Activity coefficients in octanol (,o) were determined from Koa and reported supercooled liquid vapor pressures (p), and these were in the range of 0.3 to 12, indicating near-ideal solution behavior. Differences in Koa values for structural isomers of hexachlorocyclohexane were also explored. A Koa -based model was described for predicting the partitioning of OC pesticides to aerosols and used to calculate particulate fractions at 25 and ,10°C. The model also agreed well with experimental results for several OC pesticides that were equilibrated with urban aerosols in the laboratory. A log-log regression of the particle-gas partition coefficient versus Koa had a slope near unity, indicating that octanol is a good surrogate for the aerosol organic matter. [source]

    Citrate-mediated increase in the uptake of weathered 2,2-bis(p -chlorophenyl)1,1-dichloroethylene residues by plants

    Jason C. White
    Abstract Experiments were conducted to determine the ability of citrate to enhance the plant uptake of weathered 2,2-bis(p -chlorophenyl) 1,1-dichloroethylene (p,p,-DDE) from soil. Plots containing three rows of clover, mustard, hairy vetch, or rye grass were constructed in soils containing p,p,-DDE. On 11 occasions, the rows of each crop received water or sodium citrate (0.005 or 0.05 M). For each crop, there were significant reductions in p,p,-DDE concentration in the soil fractions (near root and rhizosphere) closely associated with the plant versus bulk soil. The roots of each crop accumulated 2 to 5 times more of the weathered contaminant (dry wt) than present in the bulk soil. Citrate (0.05 M) increased the concentration of p,p,-DDE in the roots of clover, mustard, and hairy vetch by 39% compared with vegetation that received water. In batch desorption studies, the release of weathered p,p,-DDE was significantly greater in the presence of 0.05 M citrate than in water. Citrate increased the extracted aqueous concentrations of five metal ions (Al, Fe, Ca, K, Mn) from soil by five- to 23-fold over distilled water. We hypothesize that citrate physically disrupts the soil through chelation of structural metal ions and release of bound humic material, facilitating p,p,-DDE availability and uptake by plants. [source]

    Kinetics of Bis(p -nitrophenyl)phosphate (BNPP) Hydrolysis Reactions with Trivalent Lanthanide Complexes of N -Hydroxyethyl(ethylenediamine)- N,N,,N, -triacetate (HEDTA),

    C. Allen Chang
    Abstract Kinetic studies of hydrolysis reactions of BNPP [sodium bis(p -nitrophenyl)phosphate] with trivalent lanthanide (Ln3+) complexes of HEDTA [HEDTA = N -hydroxyethyl(ethylenediamine)- N,N,,N, -triacetate] were performed at pH 6.96,11.34 and 25 °C by a spectrophotometric method and by HPLC analysis. The reaction rates increase with increasing atomic number of lanthanide and solution pH from PrHEDTA to EuHEDTA and then decrease for heavier LnHEDTA complexes. Plots of pseudo-first-order rate constants (kobs) vs. pH could be fitted to the equation kobs = kLnL(OH)[LnL]T/{1,+,exp[,2.303(pH,,,pKh)]}, where kLnL(OH) is the rate constant for the reaction of LnHEDTA(OH), with BNPP, Kh is the hydrolysis constant of LnHEDTA, and [LnL]T is the total concentration of LnHEDTA. The pKh values obtained by the kinetic method are in the range 8.2,10.3 and are similar to those measured by potentiometric methods. At [LnL]T = 10,70 mM and pH 10.5, most of the observed pseudo-first-order rate constants could be fitted to a simple saturation kinetic model, kobs = k1K[LnHEDTA(OH),]/{1 + K[LnHEDTA(OH),]}, where K is the equilibrium constant for the formation for LnHEDTA(OH),BNPP and is in the range 2,147 M,1. The k1 values are in the range 1.12,×,10,5,2.71,×,10,3 s,1. The kobs data for TbHEDTA and HoHEDTA were fitted to a quadratic equation. It was observed that the dinuclear species are more reactive. ESI mass spectrometry confirmed that the reaction between BNPP and EuHEDTA is a simple hydrolysis but not a transesterification, presumably because the three inner-sphere coordinated water molecules are far away from the coordinated hydroxyethyl group. Hydrolysis is likely to occur by proton transfer from one inner-sphere coordinated water molecule to the deprotonated ethyl oxide group followed by nucleophilic attack of the resulting hydroxide ion on the bonded BNPP anion.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source]

    Changes in organic matter, nitrogen, phosphorus and cations in soil as a result of fire and water erosion in a Mediterranean landscape

    E. Gimeno-García
    Summary Fire affects large parts of the dry Mediterranean shrubland, resulting in erosion and losses of plant nutrients. We have attempted to measure these effects experimentally on a calcareous hillside representative of such shrubland. Experimental fires were made on plots (4 m × 20 m) in which the fuel was controlled to obtain two different fire intensities giving means of soil surface temperature of 439°C and 232°C with temperatures exceeding 100°C lasting for 36 min and 17 min. The immediate and subsequent changes induced by fire on the soil's organic matter content and other soil chemical properties were evaluated, together with the impact of water erosion. Seven erosive rain events, which occurred after the experimental fires (from August 1995 to December 1996), were selected, and on them runoff and sediment produced from each plot were measured. The sediments collected were weighed and analysed. Taking into account the variations induced by fire on the soil properties and their losses by water erosion, estimates of the net inputs and outputs of the soil system were made. Results show that the greatest losses of both soil and nutrients took place in the 4 months immediately after the fire. Plots affected by the most intense fire showed greater losses of soil (4077 kg ha,1) than those with moderate fire intensity (3280 kg ha,1). The unburned plots produced the least sediment (72.8 kg ha,1). Organic matter and nutrient losses by water erosion were related to the degree of fire intensity. However, the largest losses of N-NH4+ and N-NO3, by water erosion corresponded to the moderate fire (8.1 and 7.5 mg N m,2, respectively). [source]


    EVOLUTION, Issue 2 2005
    Christina M. Kavanaugh
    Abstract It has been hypothesized that new, spontaneous mutations tend to reduce fitness more severely in more stressful environments. To address this hypothesis, we grew plants representing 20 Arabidopsis thaliana mutationaccumulation (M-A) lines, advanced to generation 17, and their progenitor, in differing light conditions. The experiment was conducted in a greenhouse, and two treatments were used: full sun and shade, in which influx of red light was reduced relative to far-red. The shade treatment was considered the more stressful because mean absolute fitness was lower in that treatment, though not significantly so. Plants from generation 17 of M-A developed significantly faster than those from generation 0 in both treatments. A significant interaction between generation and treatment revealed that, counter to the hypothesis, M-A lines tended to have higher fitness on average relative to the progenitor in the shaded conditions, whereas, in full sun, the two generations were similar in fitness. A secondary objective of this experiment was to characterize the contribution of new mutations to genotype x environment interaction. We did not, however, detect a significant interaction between M-A line and treatment. Plots of the line-specific enviromental responses indicate no tendency of new mutations to contribute to fitness trade-offs between environments. They also do not support a model of conditionally deleterious mutation, in which a mutatn reduces fitness only in a particular environment. These results suggest that interactions between genotype and light environment previously documented for A. thaliana are not explicable primarily as a consequence of steady input of spontaneous mutations having environment-specific effects. [source]

    Spatial patterns and environmental factors affecting the presence of Melampsorella caryophyllacearum infections in an Abies alba forest in NE Spain

    FOREST PATHOLOGY, Issue 3 2006
    A. Solla
    Summary The presence of trunk swellings caused by the rust fungus Melampsorella caryophyllacearum was systematically surveyed in an Abies alba forest (Irati, NE Spain), using 1237 circular plots (diameter = 18 m). The relationship between fungal presence and several abiotic (aspect, elevation, distance to the nearest river and slope) and biotic factors (basal area of A. alba and/or Fagus sylvatica, shrub, fern and herb cover) was assessed through correlation and ordination analyses. Additionally, the spatial pattern of the presence of diseased trees was described using Ripley's K function. Southern-aspect plots had a significantly lower presence of diseased trees than plots-oriented north, east and west. Plots with diseased trees were located at a significantly lower elevation, and at a shorter distance to the river than plots without infections. Plots with diseased trees had almost twice the average A. alba basal area, and less average F. sylvatica basal area than plots without diseased trees. However, similar mean values of slope and shrub, fern and herb cover were found in both types of plots. The disease showed spatial aggregation in patches with a mean radius of ca. 900 m. The implications of the results for disease management are discussed. Résumé La présence de renflements sur les troncs causés par l'agent de la rouille, Melampsorella caryophyllacearum, a étéétudiée de façon systématique dans une forêt d'Abies alba (Irati, NE Espagne), en utilizant 1237 placettes circulaires (diamètre de 18 m). Les relations entre la présence du champignon et divers facteurs abiotiques (orientation, altitude, distance à la rivière la plus proche, pente) et biotiques ( surface terrière de A. alba et/ou Fagus sylvatica, abondance de la couverture herbacée et abondance d'arbustes et fougères) ont étéétudiées par analyses de corrélation et d'ordination. D'autre part, la structure spatiale de la présence d'arbres infectés a été décrite en utilizant la fonction K de Ripley. Les placettes exposées au sud présentent moins fréquemment des arbres malades que celles exposées au nord, à l'est ou à l'ouest. Les placettes avec des arbres malades sont situées à une altitude significativement plus faible et à une distance plus faible d'une rivière que les placettes sans infections, et elles présentent une surface terrière 2 fois plus forte en moyenne pour A. alba, et plus faible pour F. sylvatica, que les placettes non-infectées. Toutefois, des valeurs moyennes équivalentes pour la pente, la couverture herbacée et l'abondance d'arbustes et fougères, sont observées pour les deux types de placettes. La maladie montre une agrégation spatiale en foyers d'un rayon moyen de 900 m. Les résultats sont discutés dans une perspective de gestion de la maladie. Zusammenfassung Das Vorkommen von durch den Rostpilz Melampsorella caryophyllacearum verursachten Stammdeformationen wurde in einem Abies alba - Wald (Irati, NO-Spanien) auf 1237 kreisförmigen Probeflächen (Durchmesser 18 m) systematisch erfasst. Die Beziehung zwischen dem Pilzvorkommen und mehreren abiotischen (Exposition, Meereshöhe, Distanz zum nächsten Fluss, Hangneigung) und biotischen Faktoren (Deckungsgrad von A. alba und/oder Fagus sylvatica, Strauch-, Farn- und Krautschicht) wurden durch Korrelations- und Ordinations-Analysen überprüft. Zudem wurden räumliche Muster der befallenen Bäume mit Hilfe von Ripley's K-Funktion beschrieben. In südexponierten Probeflächen kamen signifikant weniger erkrankte Bäume vor als in nach Norden, Osten und Westen orientierten Standorten. Flächen mit Befall lagen in signifikant geringerer Meereshöhe und kürzerer Distanz zum nächsten Fluss als solche ohne Befall. Zudem hatten sie beinahe die doppelte Basalfläche mit A. alba und eine durchschnittliche geringere Basalfläche mit F. sylvatica. Die durchschnittlichen Werte für die Strauch-, Farn- und Krautschicht sowie die Hangneigung unterschieden sich jedoch nicht in den Flächen mit und ohne Befall. Erkrankte Bäume waren räumlich aggregiert mit einem mittleren Radius von ca. 900 m. Die Bedeutung dieser Befunde für das Krankheitsmanagement wird diskutiert. [source]

    Soil organic carbon contents in long-term experimental grassland plots in the UK (Palace Leas and Park Grass) have not changed consistently in recent decades

    Abstract A recent report of widespread declines in soil organic C (SOC) in the UK over the 10,25 years until the early 2000s has focussed attention on the importance of resampling previously characterized sites to assess long-term trends in SOC contents and the importance of soils as a potentially volatile and globally significant reservoir of terrestrial C. We have used two sets of long-term experimental plots which have been under constant and known management for over a century and for which historical data exist that allow comparison over recent decades to determine what, if any, changes in SOC content have occurred. The plots used are the Palace Leas (PL) Meadow Hay Plots in north-east England (UK) established in 1897, and from the Park Grass (PG) Continuous Hay experiment established in 1856 at Rothamsted in south-east England. Collectively, these plots represent the only grassland sites in the UK under long-term management where changes in SOC over several decades can be assessed, and are probably unique in the world. The plots have received different manure and fertilizer treatment and have been under known management for at least 100 years. In 1982, total SOC contents were determined for the 0,27 cm layer of six of the PL plots using measurements of SOC concentrations, bulk density and soil depth. In 2006, the same six PL plots were resampled and SOC contents determined again. Four of the plots showed no net change in SOC content, but two plots showed net loss of SOC of 15% and 17% (amounting to decreases of 18 and 15 t C ha,1) since 1982. However, these differences in total SOC content were in a similar range to the variations in bulk density (6,31%) with changing soil water content. In 1959, the soil masses and SOC concentrations to 23 cm depth were measured on six PG plots with fertilizer and manure treatments corresponding closely with those measured on PL. In 2002, the SOC concentrations on the same plots were measured again. On three of the PG plots, SOC concentrations had declined by 2,10%, but in the other three it had increased by 4,8% between 1959 and 2002. If it is assumed that the soil bulk density had not changed over this period, the losses of SOC from the top soils ranged range from 10 to 3 t C ha,1, while the gains ranged from 4 to 7 t C ha,1. When the differences with time in SOC contents for the six PL and the six PG plots were examined using paired t -tests, that is, regarding the plots as two sets of six replicate permanent grasslands, there were no significant differences between 1982 and 2006 for the PL plots or between 1959 and 2002 for the PG plots. Thus, these independent observations on similar plots at PL and PG indicate there has been no consistent decrease in SOC stocks in surface soils under old, permanent grassland in England in recent decades, even though meteorological records for both sites indicate significant warming of the soil and air between 1980 and 2000. Because the potential influences of changes in management or land use have been definitively excluded, and measured rather than derived bulk densities have been used to convert from SOC concentrations to SOC amounts, our observations question whether for permanent grassland in England, losses in SOC in recent decades reported elsewhere can be attributed to widespread environmental change. [source]

    The effect of small gaps in California annual grassland on above-ground biomass production

    GRASS & FORAGE SCIENCE, Issue 4 2001
    J. S. Fehmi
    Small gaps and clumped species distributions are common in grasslands. In California annual grasslands, patches of Lolium multiflorum Lam. and Bromus hordeaceus L. are often separated by gaps. These gaps potentially limit the productivity and associated resource use of these grasslands. The effect that differences in spatial aggregation, gap distribution and species mixing on 20-cm-diameter plots has on overall forage production by these two grasses was tested. There were three levels of aggregation: whole plots planted; half planted/half empty; two opposing quarters planted/two empty. Each species was planted in each distribution, and they were combined as mixed, half L. multiflorum/half B. hordeaceus and two quarters L. multiflorum/two quarters B. hordeaceus (nine treatments). Plant aggregation had no significant effect on above-ground production of whole plots, but individual tillers near gaps were significantly larger than others. Plasticity in the growth of individual annual grasses effectively buffered against variation in average productivity resulting from variations in plant distribution. There were significant (P < 0·001) differences in forage production as a result of the species the plots contained. Plots containing only L. multiflorum produced 4053 kg of dry matter (DM) ha,1, B. hordeaceus plots produced 2448 kg of DM ha,1, and plots containing both species produced 4712 kg of DM ha,1. At small scales, spatial distribution was less important than species composition in determining annual grassland productivity. [source]

    Chemo- and Enzyme-Catalyzed Reactions Revealing a Common Temperature-Dependent Dynamic Solvent Effect on Enantioselectivity

    Gianfranco Cainelli
    The enantiomeric ratio E of enzyme-catalyzed (Candida antarctica lipase and lipase PS) and chemo-catalyzed (L -proline-based diamines) acylation reactions of 1-(naphthalen-2-yl)ethanol, 2-phenylpropanol, and 2-benzylpropane-1,3-diol is dependent on solvent and temperature. Plots of ln,E vs. 1/T showed the presence of inversion temperatures (Tinv). The Tinv values for the bio-catalyzed and the chemo-catalyzed reactions are fairly in agreement, and correspond as well to the TNMR values obtained by variable-temperature 13C-NMR experiments on the substrates in the same solvent of the resolution. This result demonstrates that clustering effects in the substrate solvation manage the chemical and the enzymatic enantioselectivity, and, moreover, that the solutesolvent cluster is always the real reacting species in solution for chemical as well as for enzymatic reactions. [source]

    Influences of grass and moss on runoff and sediment yield on sloped loess surfaces under simulated rainfall

    Chengzhong Pan
    Abstract It is important to evaluate the impacts of grasses on soil erosion process so as to use them effectively to control soil and water losses on the Loess Plateau. Laboratory-simulated rainfall experiments were conducted to investigate the runoff and sediment processes on sloped loess surfaces with and without the aboveground parts of grasses and moss (GAM: grass and moss; NGAM: no grass and moss) under slope gradients of 5°, 10°, 15°, 20°, 25° and 30°. The results show that runoff from GAM and NGAM plots increased up to a slope gradient of 10° and decreased thereafter, whereas the runoff coefficients increased with gradient. The average runoff rates and runoff coefficients of NGAM plots were less than those of GAM plots except for the 5° slope. This behaviour may be due to the reduction in water infiltration under moss. The difference between GAM and NGAM plots in average runoff rates varied from 1·4 to 8%. At the same gradients, NGAM plots yielded significantly (, = 0·05) more sediment than GAM plots. Average sediment deliveries for different slopes varied from 0·119 to 3·794 g m,2 min,1 from GAM plots, and from 0·765 to 16·128 g m,2 min,1 from NGAM plots. Sediment yields from GAM plots were reduced by 45 to 85%, compared with those from the NGAM plots. Plots at 30° yielded significantly higher sediments than at the other gradients. Total sediments S increased with slope gradients G in a linear form, i.e. S = 9·25G , 39·6 with R2 = 0·77*, for the GAM plots, and in an exponential model, i.e. S = 40·4 exp(0·1042G) with R2 = 0·93**, for the NGAM plots. In all cases, sediment deliveries decreased with time, and reached a relative steady state at a rainfall duration of 14 min. Compared with NGAM plots, the final percentage reductions in sediment delivery from GAM plots were higher than those at the initial time of rainfall at all slopes. Copyright © 2006 John Wiley & Sons, Ltd. [source]

    Numerical simulation of vortical ideal fluid flow through curved channel

    N. P. Moshkin
    Abstract A numerical algorithm to study the boundary-value problem in which the governing equations are the steady Euler equations and the vorticity is given on the inflow parts of the domain boundary is developed. The Euler equations are implemented in terms of the stream function and vorticity. An irregular physical domain is transformed into a rectangle in the computational domain and the Euler equations are rewritten with respect to a curvilinear co-ordinate system. The convergence of the finite-difference equations to the exact solution is shown experimentally for the test problems by comparing the computational results with the exact solutions on the sequence of grids. To find the pressure from the known vorticity and stream function, the Euler equations are utilized in the Gromeka,Lamb form. The numerical algorithm is illustrated with several examples of steady flow through a two-dimensional channel with curved walls. The analysis of calculations shows strong dependence of the pressure field on the vorticity given at the inflow parts of the boundary. Plots of the flow structure and isobars, for different geometries of channel and for different values of vorticity on entrance, are also presented. Copyright © 2003 John Wiley & Sons, Ltd. [source]

    An approach for the calculation of magnetic field within square spiral inductors at low frequency

    Noureddin M. Ibrahim
    Abstract The magnetic field distribution within a square spiral inductor is investigated in this paper by summing closed-form expressions for the fields from each segment. Plots illustrating the variation of the normally directed B -field penetrating the surface of the spiral traces are then developed for a variety of perspectives. The expressions and insight gained represent an essential step in developing a detailed model of effects such as current crowding, which significantly limit the spiral's performance in practical circuits. Copyright © 2002 John Wiley & Sons, Ltd. [source]

    Use of serial pig body weights for genetic evaluation of daily gain

    B. Zumbach
    Summary This study examined the utility of serial weights from FIRE (Feed Intake Recording Equipment, Osborne Industries, Inc., Osborne, KS, USA) stations for an analysis of daily gain. Data included 884 132 body weight records from 3888 purebred Duroc pigs. Pigs entered the feeder station at age 77,149 days and left at age 95,184 days. A substantial number of records were abnormal, showing body weight close to 0 or up to twice the average weight. Plots of body weights for some animals indicated two parallel growth curves. Initial editing used a robust regression, which was a two-step procedure. In the first step, a quadratic growth curve was estimated assuming small or 0 weights for points far away from the curve; the process is iterative. In the second step, weights more than 1.5 SD from the estimated growth curve were treated as outliers. The retained body weight records (607 597) were averaged to create average daily weight (170 443) and then used to calculate daily gains (152 636). Additional editing steps included retaining only animals with ,50 body weight records and SD of the daily gain ,2 kg, followed by removing records outside 3 SD from the mean for given age, across all the animals , the resulting data set included 69 068 records of daily gain from 1921 animals. Daily gain based on daily, weekly and bi-weekly intervals was analysed using repeatability models. Heritability estimates were 0.04, 6 and 9%, respectively. The last two estimates correspond to heritability of 28% for a 12 week interval. For daily gain averaged weekly, the estimate of heritability obtained with a random regression model varied from 0.07 to 0.10. After extensive editing, body weight records from automatic feeding stations are useful for genetic analyses of daily gain from weekly or bi-weekly but not daily intervals. [source]

    Evaluation of an indirect serum ELISA and a bacteriological faecal culture test for diagnosis of Salmonella serotype Dublin in cattle using latent class models

    L.R. Nielsen
    Abstract Aims:, To evaluate a conventional bacteriological test based on faecal culture and an indirect serum ELISA for detection of S. Dublin infected cattle. To compare the predictive values of the two tests in relation to the prevalence. Methods and Results:, A total of 4531 paired samples from cattle in 29 dairy herds were analysed for presence of S. Dublin bacteria in faeces and immunoglobulins directed against S. Dublin lipopolysaccharide in an indirect serum ELISA. Sensitivity and specificity were estimated at two ELISA cut-off values using a validation method based on latent class models, which presumably provides less biased results than traditional validation methods. Stratification of data into three age groups gave significantly better estimates of test performance of the ELISA. Receiver operating characteristic (ROC) curves were constructed for comparison of overall performance of the ELISA between the three age groups. The sensitivity of the faecal culture test was low (6,14%). ELISA appeared to have a higher validity for animals aged 100,299 days of age than older or younger animals. Overall, the negative predictive value of the ELISA was 2,10 times higher than for the faecal culture test at realistic prevalence of infection in the test population. Conclusions:, The diagnostic sensitivity of the faecal culture test for detection of S. Dublin is poor, the specificity is 1. The superior sensitivity and negative predictive value of the serum ELISA makes this test preferable to faecal culture as an initial screening test and for certification of herds not infected with S. Dublin. Significance and Impact of the Study:, A quantitative estimate of the sensitivity of a faecal culture test for S. Dublin in a general population was provided. ELISA was shown to be an appropriate alternative diagnostic test. Preferably, samples from animals aged 100,299 days of age should be used as these give the best overall performance of the ELISA. Plots of ROC curves and predictive values in relation to prevalence facilitates optimisation of the ELISA cut-off value. [source]

    Rheological behavior and mechanical properties of high-density polyethylene blends with different molecular weights

    Lu Bai
    Abstract The dynamic rheological and mechanical properties of the binary blends of two conventional high-density polyethylenes [HDPEs; low molecular weight (LMW) and high molecular weight (HMW)] with distinct different weight-average molecular weights were studied. The rheological results show that the rheological behavior of the blends departed from classical linear viscoelastic theory because of the polydispersity of the HDPEs that we used. Plots of the logarithm of the zero shear viscosity fitted by the Cross model versus the blend composition, Cole,Cole plots, Han curves, and master curves of the storage and loss moduli indicated the LMW/HMW blends of different compositions were miscible in the melt state. The tensile yield strength of the blends generally followed the linear additivity rule, whereas the elongation at break and impact strength were lower than those predicted by linear additivity; this suggested the incompatibility of the blends in solid state. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source]

    An Analysis of the Distribution of Extreme Share Returns in the UK from 1975 to 2000

    G. D. Gettinby
    This paper seeks to characterise the distribution of extreme returns for a UK share index over the years 1975 to 2000. In particular, the suitability of the following distributions is investigated: Gumbel, Frechet, Weibull, Generalised Extreme Value, Generalised Pareto, Log-Normal and Generalised Logistic. Daily returns for the FT All Share index were obtained from Datastream, and the maxima and minima of these daily returns over a variety of selection intervals were calculated. Plots of summary statistics for the weekly maxima and minima on statistical distribution maps suggested that the best fitting distribution would be either the Generalised Extreme Value or the Generalised Logistic. The results from fitting each of these two distributions to extremes of a series of UK share returns support the conclusion that the Generalised Logistic distribution best fits the UK data for extremes over the period of the study. The Generalised Logistic distribution has fatter tails than either the log-normal or the Generalised Extreme Value distribution, hence this finding is of importance to investors who are concerned with assessing the risk of a portfolio. [source]

    The existence of secondary orbital interactions

    Chaitanya S. Wannere
    Abstract B3LYP/6-311+G** (and MP2/6-311+G**) computations, performed for a series of Diels-Alder (DA) reactions, confirm that the endo transition states (TS) and the related Cope-TSs are favored energetically over the respective exo -TSs. Likewise, the computed magnetic properties (nucleus-independent chemical shifts and magnetic susceptibililties) of the endo - (as well as the Cope) TS's reveal their greater electron delocalization and greater aromaticity than the exo -TS's. However, Woodward and Hoffmann's original example is an exception: their endo -TS model, involving the DA reaction of a syn - with an anti -butadiene (BD), actually is disfavored energetically over the corresponding exo -TS; magnetic criteria also do not indicate the existence of SOI delocalization in either case. Instead, a strong energetic preference for endo -TSs due to SOI is found when both BDs are in the syn conformations. This is in accord with Alder and Stein's rule of "maximum accumulation of double bonds:" both the dienophile and the diene should have syn conformations. Plots along the IRC's show that the magnetic properties typically are most strongly exalted close to the energetic TS. Because of SOI, all the points along the endo reaction coordinates are more diatropic than along the corresponding exo pathways. We find weak SOI effects to be operative in the endo -TSs involved in the cycloadditions of cyclic alkenes, cyclopropene, aziridine, cyclobutene, and cyclopentene, with cyclopentadiene. While the endo -TSs are only slightly lower in energy than the respective exo -TSs, the magnetic properties of the endo -TS's are significantly exalted over those for the exo -TS's and the Natural Bond Orbitals indicate small stabilizing interactions between the methylene cycloalkene hydrogen orbitals (and lone pairs in case of aziridine) with ,-character and the diene , MOs. © 2006 Wiley Periodicals, Inc. J Comput Chem 2007 [source]

    Structure, magnetizability, and nuclear magnetic shielding tensors of bis-heteropentalenes.


    Abstract The geometry of the heteropentalenes formed by two phosphole units has been determined at the DFT level. The magnetic susceptibility and the nuclear magnetic shielding at the nuclei of these systems have also been calculated using gauge-including atomic orbitals and a large Gaussian basis set to achieve near Hartree,Fock estimates. A comparative study of the various isomers, of their flattened analogs, and of the parent phosphole molecule, shows that the [3,4-c] isomer is the most aromatic system in the set considered, assuming diatropicity and degree of planarity as indicators, even if it is the less stable in terms of total molecular energy. Plots of magnetic field-induced current densities confirm diatropicity of P-containing bis-heteropentalenenes, showing, however, significant differences from the analogous systems with distinct heteroatoms. The maps give evidence of spiral flow nearby CC bonds, compatible with prevalent distortive behavior of , electrons exalted by pyramidalization at P, and competing against the , electron compression, which would favor planar structure. © 2005 Wiley Periodicals, Inc. J Comput Chem 27: 344,351, 2006 [source]

    Wave functions derived from experiment.


    Abstract The constrained Hartree,Fock method using experimental X-ray diffraction data is extended and applied to the case of noncentrosymmetric molecular crystals. A new way to estimate the errors in derived properties as a derivative with respect to added Gaussian noise is also described. Three molecular crystals are examined: ammonia [NH3], urea [CO(NH2)2], and alloxan [(CO)4(NH)2]. The energetic and electrical properties of these molecules in the crystalline state are presented. In all cases, an enhancement of the dipole moment is observed upon application of the experimental constraint. It is found that the phases of the structure factors are robustly determined by the constrained Hartree,Fock model, even in the presence of simulated noise. Plots of the electron density, electrostatic potential, and the electron localization function for the molecules in the crystal are displayed. In general, relative to the Hartree,Fock model, there is a depletion of charge around hydrogen atoms and lone pair regions, and a build-up of charge within the molecular framework near nuclei, directed along the bonds. The electron localization function plots reveal an increase in the pair density between vicinal hydrogen atoms. © 2003 Wiley Periodicals, Inc. J Comput Chem 24: 470,483, 2003 [source]

    Mesoscale distribution patterns of Amazonian understorey herbs in relation to topography, soil and watersheds

    JOURNAL OF ECOLOGY, Issue 5 2005
    Summary 1Many authors have suggested that topography and soils are the major determinants of species distributions and community patterns at small or regional scales, but few studies addressed the patterns at mesoscales. We used Reserva Ducke (100 km2) as a model to analyse the effects of soil, topography and watersheds on the variation of the herb community composition, and to determine the relative importance of the environmental factors on species composition. 2Taxonomic groups are frequently used as surrogates in studies of biodiversity distribution and complementarity, but their efficacy is controversial. We therefore studied the correlations between the distributional patterns of three different herb groups (Marantaceae, pteridophytes and ,others') and their responses to environmental predictors. 3Terrestrial herbs were sampled in 59 plots of 250 × 2 m, systematically distributed over the reserve. Plots followed isoclines of altitude, to minimize the internal variation of soil. Composition of the total herb community and of the three herb groups was summarized with PCoA. 4Soil structure, represented by PCA axes, was the main determinant of the variation in herb composition for all groups, but slope affected only pteridophytes. Soil and topography explained less than one-third of the variance in community data. Herb composition was significantly different between watersheds, but watersheds differ only slightly in soil parameters. Our results indicate high turnover in species composition, on spatial scales of 5,10 km in central Amazonia, which is not necessarily associated with soil change. 5Compositional patterns of the three groups analysed were significantly correlated, but with low values for the correlation coefficient. Although composition was correlated, the responses to environmental predictors differed among groups, and the use of one group as a surrogate will miss around 50% of the variation in other groups. 6Although important, soil and topography alone cannot predict herb community structure. Knowledge of geographical, historical or other landscape features, such as watershed morphology, may therefore be necessary to predict the turnover patterns over mesoscales. Moreover, the same factors may not have the same effectiveness as predictors of the structure of seemingly similar biological groups. [source]

    Peak width-mass correlation in CID MS/MS of isomeric oligosaccharides using traveling-wave ion mobility mass spectrometry

    Tohru Yamagaki
    Abstract Isomeric oligosaccharides ,-cyclodextrin (,-CD), glucosyl-,CD (Glc1 -,CD) and maltosyl-,CD (Glc2 -,CD) were analyzed by traveling-wave ion mobility (twIM) mass spectrometry (MS). Their formation of multicharged multimers differed from each other. The ion mobility-mass spectrometry was useful in the self-assembling and complex formation analyses of CD isomers. The drift times of the isomers and their product ions with the same mass were almost the same in collision-induced dissociation (CID) MS/MS. In contrast, the ion mobility peak widths were sensitive to structural differences of the isomeric product ions. The twIM peak width (ms - µs) of the product ions [M , Glcn + H]+ (n = 0 , 6) of ,-CD correlated linearly with their masses (Da); the large and/or long chain product ions had wider peak widths, which were much wider than those from the general diffusion effect. This was a novel and useful ,trend line' to discriminate between the three isomers. Plots of [M , Glc2 , 6 + H]+ of Glc1 -,CD and [M , Glc3 , 6 + H]+ of Glc2 -,CD product ions' plots were on the same trend line as ,-CD. The plots of [M , Glc1 + H]+ of Glc1 -,CD and [M , Glc1, 2 + H]+ of Glc2 -,CD strayed from the ,-CD line; their peak widths were narrower than those of ,-CD. These results indicated that product ions from the chemical species of Glc1 -, CD and Glc2 -,CD retained their CD structure. Analyses of the IM peak widths enable us to elucidate the structures of the product ions. Copyright © 2009 John Wiley & Sons, Ltd. [source]

    Promoting felt responsibility for constructive change and proactive behavior: exploring aspects of an elaborated model of work design,

    Jerry Bryan Fuller
    Although new theoretical models that are suggestive of how work design might be used to foster proactive motivation and proactive performance have been proposed, these models need further elaboration and testing if they are to be useful tools for contemporary organizations. Accordingly, we examine the extent to which feelings of responsibility for constructive change is a proactive psychological mechanism that explains how work design characteristics influence constructive change-oriented behavior and proactive performance. Specifically, we examine job autonomy, position in the organizational hierarchy, access to resources, access to strategy-related information, and role ambiguity as antecedents to felt responsibility for constructive change (FRCC). We also examine the extent to which feelings of responsibility for constructive change are positively related to voice behavior (i.e., constructive, change-oriented communication) and continuous improvement (i.e., proactive role performance). Results indicate hierarchical position and access to resources are positively related to FRCC. Results also indicate proactive personality moderates the relationship between access to resources and FRCC and the relationship between access to strategy-related information and FRCC. Plots of the interactions reveal that these relationships are enhanced for individuals with proactive personalities. The results also indicate that FRCC is positively related to voice behavior and continuous improvement. Perhaps more importantly, the results suggest that FRCC explains the psychological process by which structural and socio-structural forces influence proactive behavior. The results are discussed as they pertain to updated work design theory and theories of high involvement work systems, job characteristics, and leadership prototypes. Copyright © 2006 John Wiley & Sons, Ltd. [source]