Weed control in organic cereals and pulses

Weeds remain one of the most significant agronomic problems associated with organic arable crop production. It is recognised that a low weed population can be beneficial to the crop as it provides food and habitat for a range of beneficial organisms (Millington et al., 1990; Clements et al., 1994; Aebischer, 1997; Fuller, 1997; Patriquin et al., 1998). However, above critical population thresholds, weeds can significantly reduce crop yield and quality in conventional (Cussans, 1968; Hewson et al., 1973; Cousens, 1985; Cudney et al., 1989) and organic (Bulson, 1991) crops alike. The challenge for organic farmers is to manage weeds in such a way as to accommodate their beneficial effects whilst still producing an acceptable crop

Screening versus routine practice in detection of atrial fibrillation in patients aged 65 or over: Screening versus routine practice in detection cluster randomised controlled trial

Objectives : To assess whether screening improves the detection of atrial fibrillation (cluster randomisation) and to compare systematic and opportunistic screening. Design : Multicentred cluster randomised controlled trial, with subsidiary trial embedded within the intervention arm. Setting : 50 primary care centres in England, with further individual randomisation of patients in the intervention practices. Participants : 14,802 patients aged 65 or over in 25 intervention and 25 control practices. Interventions : Patients in intervention practices were randomly allocated to systematic screening (invitation for electrocardiography) or opportunistic screening (pulse taking and invitation for electrocardiography if the pulse was irregular). Screening took place over 12 months in each practice from October 2001 to February 2003. No active screening took place in control practices. Main outcome measure : Newly identified atrial fibrillation. Results : The detection rate of new cases of atrial fibrillation was 1.63% a year in the intervention practices and 1.04% in control practices (difference 0.59%, 95% confidence interval 0.20% to 0.98%). Systematic and opportunistic screening detected similar numbers of new cases (1.62% v 1.64%, difference 0.02%, −0.5% to 0.5%). Conclusion : Active screening for atrial fibrillation detects additional cases over current practice. The preferred method of screening in patients aged 65 or over in primary care is opportunistic pulse taking with follow-up electrocardiography. Trial registration Current Controlled Trials ISRCTN19633732

Affinities and Beyond! Developing Ways of Seeing in Online Spaces

This article presents an insider view of an online community of adults involved in sharing digital photography through a host website, Flickr. It describes how reciprocal teaching and learning partnerships in a dynamic multimodal environment are achieved through the creation of a ‘Third Space’ or ‘Affinity Space’, where ‘Funds of Knowledge’ are shared and processed in such a way that new meanings and discourses are generated. It is argued that this process is evidence of valuable learning and of the deepening of global understandings within the local space of Flickr. The new understandings are at least partly identifiable on the Flickr space, through the co-constructed ‘folksonomy’ or ‘online taxonomy’ of ways of looking at the world. Further, the article provides evidence for broadening existing definitions of literacy, at a time when the visual mode increasingly works interactively with verbal cues and explanations

O.P.E. and Power Corrections to the QCD coupling constant

Lattice data seems to show that power corrections should be convoked to describe appropriately the transition of the QCD coupling constant running from U.V. to I.R. domains. Those power corrections for the Landau-gauge MOM coupling constant in a pure Yang-Mills theory (N_f=0) are analysed in terms of Operator Product Expansion (O.P.E.) of two- and three-point Green functions, the gluon condensate emerging from this study. The semi-classical picture given by instantons can be also used to look for into the nature of the power corrections and gluon condensate.Comment: 5 pages, talk given at XXX International Meeting on Fundamental Physics, Jaca 200

Adiabatic response for Lindblad dynamics

We study the adiabatic response of open systems governed by Lindblad evolutions. In such systems, there is an ambiguity in the assignment of observables to fluxes (rates) such as velocities and currents. For the appropriate notion of flux, the formulas for the transport coefficients are simple and explicit and are governed by the parallel transport on the manifold of instantaneous stationary states. Among our results we show that the response coefficients of open systems, whose stationary states are projections, is given by the adiabatic curvature.Comment: 33 pages, 4 figures, accepted versio

Differential disease incidence and mortality of inner and outer reef corals of the upper Florida Keys in association with a white syndrome outbreak

The Florida Keys Reef Tract has suffered extraordinary losses in live coral cover over the past four decades and is now battling an unprecedented coral disease outbreak. Here, colonies of Siderastrea siderea (Ellis and Solander, 1786) and Pseudodiploria strigosa (Dana, 1846) were tracked over 3 yrs (2015-2017) across two pairs of inner and outer reef sites in the upper keys, offering a unique perspective into the distribution of disease throughout the reef tract. We found that outer reef colonies of both coral species exhibited greater disease incidence and mortality associated with this ongoing epidemic, while inner patch reef colonies remained largely unaffected. These findings suggest that ecological or biological factors that differentiate coral populations across these reef zones may play an important role in susceptibility to disease

The intrinsic features of the specific heat at half-filled Landau levels of two-dimensional electron systems

The specific heat capacity of a two-dimensional electron gas is derived for two types of the density of states, namely, the Dirac delta function spectrum and that based on a Gaussian function. For the first time, a closed form expression of the specific heat for each case is obtained at half-filling. When the chemical potential is temperature-independent, the temperature is calculated at which the specific heat is a maximum. Here the effects of the broadening of the Landau levels are distinguished from those of the different filling factors. In general, the results derived herein hold for any thermodynamic system having similar resonant states.Comment: 11 pages, 1 figure, to appear in J Low Temp Phys (2010

The Future Evolution of White Dwarf Stars Through Baryon Decay and Time Varying Gravitational Constant

Motivated by the possibility that the fundamental ``constants'' of nature could vary with time, this paper considers the long term evolution of white dwarf stars under the combined action of proton decay and variations in the gravitational constant. White dwarfs are thus used as a theoretical laboratory to study the effects of possible time variations, especially their implications for the future history of the universe. More specifically, we consider the gravitational constant $G$ to vary according to the parametric relation $G = G_0 (1 + t/t_\ast)^{-p}$, where the time scale $t_\ast$ is the same order as the proton lifetime. We then study the long term fate and evolution of white dwarf stars. This treatment begins when proton decay dominates the stellar luminosity, and ends when the star becomes optically thin to its internal radiation.Comment: 12 pages, 10 figures, accepted to Astrophysics and Space Scienc

The CAT Imaging Telescope for Very-High-Energy Gamma-Ray Astronomy

The CAT (Cherenkov Array at Themis) imaging telescope, equipped with a very-high-definition camera (546 fast phototubes with 0.12 degrees spacing surrounded by 54 larger tubes in two guard rings) started operation in Autumn 1996 on the site of the former solar plant Themis (France). Using the atmospheric Cherenkov technique, it detects and identifies very high energy gamma-rays in the range 250 GeV to a few tens of TeV. The instrument, which has detected three sources (Crab nebula, Mrk 421 and Mrk 501), is described in detail.Comment: 24 pages, 15 figures. submitted to Elsevier Preprin