Canine and feline pregnancy loss due to viral and non-infectious causes : a review.

Among the causes for pregnancy loss, viruses and non-infectious factors are among the most important. In both dogs and cats, research and clinical evidence provide proof that there is an increasing incidence of pregnancy loss associated with infectious diseases like herpesvirus, as well as the presence of toxicants or chemicals in the animal's diet and environment. Endocrine causes must be taken into consideration when dealing with pregnancy loss. This review will cover the most recent knowledge regarding viral and non-infectious of pregnancy losses in the dog and cat

Crop yield gap and stability in organic and conventional farming systems

A key challenge for sustainable intensification of agriculture is to produce increasing amounts of food and feed with minimal biodiversity loss, nutrient leaching, and greenhouse gas emissions. Organic farming is considered more sustainable, however, less productive than conventional farming. We analysed results from an experiment started under identical soil conditions comparing one organic and two conventional farming systems. Initially, yields in the organic farming system were lower, but approached those of both conventional systems after 10-13 years, while requiring lower nitrogen inputs. Unexpectedly, organic farming resulted in lower coefficient of variation, indicating enhanced spatial stability, of pH, nutrient mineralization, nutrient availability, and abundance of soil biota. Organic farming also resulted in improved soil structure with higher organic matter concentrations and higher soil aggregation, a profound reduction in groundwater nitrate concentrations, and fewer plant-parasitic nematodes. Temporal stability between the three farming systems was similar, but when excluding years of Phytophthora outbreaks in potato, temporal stability was higher in the organic farming system. There are two non-mutually exclusive mechanistic explanations for these results. First, the enhanced spatial stability in the organic farming system could result from changes in resource-based (i.e. bottom-up) processes, which coincides with the observed higher nutrient provisioning throughout the season in soils with more organic matter. Second, enhanced resource inputs may also affect stability via increased predator-based (i.e. top-down) control. According to this explanation, predators stabilize population dynamics of soil organisms, which is supported by the observed higher soil food web biomass in the organic farming system.We conclude that closure of the yield gap between organic and conventional farming can be a matter of time and that organic farming may result in greater spatial stability of soil biotic and abiotic properties and soil processes. This is likely due to the time required to fundamentally alter soil properties.Article / Letter to editorCentrum voor Milieuwetenschappen Leide

Een hernieuwde kijk op individuele besluitvorming in de glastuinbouw

In dit rapport wordt verslag gedaan van een verkennend onderzoek naar verschillen in de besluitvorming van individuele glastuinders en naar de rol die de 'omgeving' hierbij speelt. Onderzoeksvragen zijn: Hoe verloopt het besluitvormingsproces van een glastuinder bij investeringsbeslissingen omtrent energiebesparing? Wat is de rol van 'externen' (bedrijfs-adviseurs, collega-telers, en dergelijke) bij dit proces? Hoe krijgen we zicht op de interactie tussen de glastuinder en zijn of haar omgeving? Op basis van de literatuur is een conceptueel model opgesteld. Bij in totaal 70 glastuinders zijn, via een workshop en telefonische interviews, data verzameld met be-trekking tot persoonlijkheidskenmerken, attituden en informatieverzamelingsgedrag. Deze data zijn vervolgens gerelateerd aan hun bedrijfsgegevens die reeds eerder vastgelegd zijn in het Bedrijven-Informatienet van LEI B.V. De resultaten laten zien dat er significante relaties zijn tussen persoonlijkheidskenmerken van glastuinders, bedrijfsfactoren en informatieverzamelingsgedrag. Het persoonlijkheidskenmerk 'extraversie' en de bedrijfsfactor 'oppervlakte van het bedrijf' ble-ken (deels) te kunnen verklaren waarom de ene glastuinder zelf de uiteindelijke beslissing neemt en de andere glastuinder het overlaat aan een 'extern' persoon

Partial Flavor Symmetry Restoration for Chiral Staggered Fermions

We study the leading discretization errors for staggered fermions by first constructing the continuum effective Lagrangian including terms of O(a^2), and then constructing the corresponding effective chiral Lagrangian. The terms of O(a^2) in the continuum effective Lagrangian completely break the SU(4) flavor symmetry down to the discrete subgroup respected by the lattice theory. We find, however, that the O(a^2) terms in the potential of the chiral Lagrangian maintain an SO(4) subgroup of SU(4). It follows that the leading discretization errors in the pion masses are SO(4) symmetric, implying three degeneracies within the seven lattice irreducible representations. These predictions hold also for perturbatively improved versions of the action. These degeneracies are observed, to a surprising degree of accuracy, in existing data. We argue that the SO(4) symmetry does not extend to the masses and interactions of other hadrons (vector mesons, baryons, etc), nor to higher order in a^2. We show how it is possible that, for physical quark masses of O(a^2), the new SO(4) symmetry can be spontaneously broken, leading to a staggered analogue of the Aoki-phase of Wilson fermions. This does not, however, appear to happen for presently studied versions of the staggered action.Comment: 26 pages, 2 figures (using psfig). Version to appear in PRD (clarifications added to introduction and section 6; typos corrected; references updated