Applying generic landscape-scale models of natural pest control to real data: Associations between crops, pests and biocontrol agents make the difference

Managing agricultural land to maximize the supply of natural pest control can help reduce pesticide use. Tools that are able to represent the relationship between landscape structure, field management and natural pest control can help in deciding which management practices should be used and where. However, the reliability and the predictive power of generic models of natural pest control is largely unknown. We applied an existing generic model of natural pest control potential based on landscape structure to nine sites in five European countries and tested the resulting values against field measurements of natural pest control. Subsequently, we added information on local level factors to test the possibility of improving model performance and predictive power. The results showed that there is generally little or no evidence of correlation between modeled and field-measured values of natural pest control. Moreover, we found high variability in the results, depending on the associations of crops, pests and biocontrol agents considered (e.g. Oilseed rape-Pollen beetle-Parasitoids) and on the different case studies. Factors at the local level, such as conservation tillage, had an overall positive effect on natural pest control, and their inclusion in the models typically increased their predictive power. Our results underline the importance of developing predictive models of natural pest control which are tailored towards specific associations between crops, pests and biocontrol agents, consider local level factors and are trained using field measurements. They would serve as important tools within farmers' decision making, ultimately supporting the shift toward a low-pesticide agriculture

Impact of Working Memory Load on fMRI Resting State Pattern in Subsequent Resting Phases

BACKGROUND: The default-mode network (DMN) is a functional network with increasing relevance for psychiatric research, characterized by increased activation at rest and decreased activation during task performance. The degree of DMN deactivation during a cognitively demanding task depends on its difficulty. However, the relation of hemodynamic responses in the resting phase after a preceding cognitive challenge remains relatively unexplored. We test the hypothesis that the degree of activation of the DMN following cognitive challenge is influenced by the cognitive load of a preceding working-memory task. METHODOLOGY/PRINCIPAL FINDINGS: Twenty-five healthy subjects were investigated with functional MRI at 3 Tesla while performing a working-memory task with embedded short resting phases. Data were decomposed into statistically independent spatio-temporal components using Tensor Independent Component Analysis (TICA). The DMN was selected using a template-matching procedure. The spatial map contained rest-related activations in the medial frontal cortex, ventral anterior and posterior cingulate cortex. The time course of the DMN revealed increased activation at rest after 1-back and 2-back blocks compared to the activation after a 0-back block. CONCLUSION/SIGNIFICANCE: We present evidence that a cognitively challenging working-memory task is followed by greater activation of the DMN than a simple letter-matching task. This might be interpreted as a functional correlate of self-evaluation and reflection of the preceding task or as relocation of cerebral resources representing recovery from high cognitive demands. This finding is highly relevant for neuroimaging studies which include resting phases in cognitive tasks as stable baseline conditions. Further studies investigating the DMN should take possible interactions of tasks and subsequent resting phases into account

Mapping of the range of operational conditions for Cu-, Fe-, and Ni-based oxygen carriers in chemical-looping combustion

Available online September 14, 2006.- El pdf del artículo es la versión post-printChemical-looping combustion (CLC) is a two-step combustion process that produces a pure CO2 stream, ready for compression and sequestration. A CLC system is composed by two reactors, an air and a fuel reactor, and an oxygen carrier (OC) circulating between the reactors, which transfers the oxygen necessary for the fuel combustion from the air to the fuel. This system can be designed similar to a circulating fluidised bed, but with the addition of a bubbling fluidised bed on the return side. A mapping of the range of operational conditions, design values, and OC characteristics is presented for the most usual metal oxides (CuO, Fe2O3, and NiO) and different fuel gases (CH4, H2, and CO). The pressure operation of a CLC system is also considered. Moreover, a comparison of the possible use of three high reactive OCs (Cu10Al-I, Fe45Al-FG, Ni40Al-FG) previously characterised is carried out. It was found that the circulation rates and the solids inventories are linked, and the possible operating conditions are closely dependent on the reactivity of the OCs. The operational limits of the solids circulation rates, given by the mass and heat balances in the system, were defined for the different type of OCs. Moreover, a plot to calculate the solids inventories in a CLC system, valid for any type of OC and fuel gas, is proposed. The minimum solids inventories depended on the fuel gas used, and followed the order CH4 > CO > H2. Values of minimum solids inventories in a range from 40 to 133 kg / MWf were found for the OCs used in this work, excepting for the reaction of Fe45Al-FG with CH4, which needs a higher amount of solids because of its low reactivity. From the economic analysis carried out it was found the cost of the OC particles does not represent any limitation to the development of the CLC technology. © 2006 Elsevier Ltd. All rights reserved.This work was carried out with financial support from the European Coal and Steel Community (Project 7220-PR/125), and the Spanish Ministry of Education and Science (Project CTQ2004- 04034).Peer Reviewe

Kinetic and morphological differentiation of Ettringites in plain and blended Portland cements using Metakaolin and the ASTM C 452-68 test. Part I: kinetic differentiation.

22 pages, 3 figures, 5 tables.[ES] En esta Parte I de la investigación, se han logrado verifi- car mediante el ensayo ASTM C 452-68, los resultados obtenidos en anteriores investigaciones realizadas con DRX y SEM y el ensayo Le Chatelier-Ansttet. Para ello, a 10 cementos Portland –6 CPO y 4 CPRS– se les añadió 20%, 30% y 40% de metakaolín (MK). Tanto los 10 CP como los 30 de sus mezclas con metakaolín (MK), se ensayaron durante 2 años, mediante dicho método ASTM C 452-68, y a sus probetas no sólo se les determinó su incremento porcentual de longitud, ∆L(%), sino además, el contenido de sulfatos de sus aguas de conservación. Otras determinaciones complementarias fueron: análisis químico de los materiales cementiceos utilizados y pro- piedades específicas de algunos cementos ensayados. Los resultados experimentales, ∆L(%) frente al tiempo, han confirmado de nuevo que la velocidad de formación de la ettringita de origen alúmina reactiva, Al2O3 r-, de las puzolanas, tiene que ser considerablemente mayor que la velocidad de formación de la ettringita de origen C3A de los CP, lo que ha sido verificado por la evolución durante todo el ensayo, del contenido de sulfatos de las aguas de conservación de las probetas. Debido a ello, se ha pro- puesto denominar a ambos tipos de ettringitas, ettringita de rápida formación, ett-rf, y ettringita de lenta forma- ción, ett-lf, respectivamente.[EN] In this first part of the study, the results obtained in prior research with XRD and SEM, as well as the Le Chatelier- Ansttet test were confirmed with the ASTM C 452-68 test. To this end, 20%, 30% and 40% metakaolin (MK) was added to ten Portland cements, six OPCs and four SRPCs. Both the ten plain PCs and the 30 metakaolin (MK) blends were tested for two years under ASTM C 452-68 specifications, determining not only the percentage increase in length, ΔL(%), of the specimens, but also the sulphate content in the curing water. Other parameters studied included: chemical analysis of the cementitious materials used and specific properties of some of the cements tested. The experimental results, ΔL(%) versus time, re-confirmed that the formation rate of ettringite from the reactive alumina, Al2O3 r-, present in the pozzolan must be substantially higher than the formation rate of ettringite from the C3A present in the PC. This was verified by the variation of the sulphate content in the specimen curing water throughout the test. In light of those findings, in this article these two types of ettringite are denominated rapid forming ettringite or ett-rf, and slow forming ettringite or ett-lf.Peer reviewe

Near-Infrared interferometry of Eta Carinae with high spatial and spectral resolution using the VLTI and the AMBER instrument

We present the first NIR spectro-interferometry of the LBV Eta Carinae. The K band observations were performed with the AMBER instrument of the ESO Very Large Telescope Interferometer using three 8.2m Unit Telescopes with baselines from 42 to 89m. The aim of this work is to study the wavelength dependence of Eta Car's optically thick wind region with a high spatial resolution of 5 mas (11 AU) and high spectral resolution. The medium spectral resolution observations (R=1,500) were performed in the wavelength range around both the HeI 2.059 micron and the Br gamma 2.166 micron emission lines, the high spectral resolution observations (R=12,000) only in the Br gamma line region. In the K-band continuum, a diameter of 4.0 +/-0.2 mas (Gaussian FWHM, fit range 28-89m) was measured for Eta Car's optically thick wind region. If we fit Hillier et al. (2001) model visibilities to the observed AMBER visibilities, we obtain 50 % encircled-energy diameters of 4.2, 6.5 and 9.6mas in the 2.17 micron continuum, the HeI, and the Br gamma emission lines, respectively. In the continuum near the Br gamma line, an elongation along a position angle of 120+/-15 degrees was found, consistent with previous VLTI/VINCI measurements by van Boekel et al. (2003). We compare the measured visibilities with predictions of the radiative transfer model of Hillier et al. (2001), finding good agreement. Furthermore, we discuss the detectability of the hypothetical hot binary companion. For the interpretation of the non-zero differential and closure phases measured within the Br gamma line, we present a simple geometric model of an inclined, latitude-dependent wind zone. Our observations support theoretical models of anisotropic winds from fast-rotating, luminous hot stars with enhanced high-velocity mass loss near the polar regions.Comment: 22 pages, 14 figures, 2 tables; A&A in pres

The Flavor Asymmetry of the Light Quark Sea from Semi-inclusive Deep-inelastic Scattering

The flavor asymmetry of the light quark sea of the nucleon is determined in the kinematic range 0.02<x<0.3 and 1 GeV^2<Q^2<10 GeV^2, for the first time from semi-inclusive deep-inelastic scattering. The quantity (dbar(x)-ubar(x))/(u(x)-d(x)) is derived from a relationship between the yields of positive and negative pions from unpolarized hydrogen and deuterium targets. The flavor asymmetry dbar-ubar is found to be non-zero and x dependent, showing an excess of dbar over ubar quarks in the proton.Comment: 7 Pages, 2 figures, RevTeX format; slight revision in text, small change in extraction of dbar-ubar and comparison with a high q2 parameterizatio

Beam-Induced Nuclear Depolarisation in a Gaseous Polarised Hydrogen Target

Spin-polarised atomic hydrogen is used as a gaseous polarised proton target in high energy and nuclear physics experiments operating with internal beams in storage rings. When such beams are intense and bunched, this type of target can be depolarised by a resonant interaction with the transient magnetic field generated by the beam bunches. This effect has been studied with the HERA positron beam in the HERMES experiment at DESY. Resonances have been observed and a simple analytic model has been used to explain their shape and position. Operating conditions for the experiment have been found where there is no significant target depolarisation due to this effect.Comment: REVTEX, 6 pages, 5 figure