Structural rearrangements that govern flow in colloidal glasses

Structural rearrangements are an essential property of atomic and molecular glasses; they are critical in controlling resistance to flow and are central to the evolution of many properties of glasses, such as their heat capacity and dielectric constant. Despite their importance, these rearrangements cannot directly be visualized in atomic glasses. We used a colloidal glass to obtain direct three-dimensional images of thermally induced structural rearrangements in the presence of an applied shear. We identified localized irreversible shear transformation zones and determined their formation energy and topology. A transformation favored successive ones in its vicinity. Using continuum models, we elucidated the interplay between applied strain and thermal fluctuations that governs the formation of these zones in both colloidal and molecular glasses.     

Vibrio anguillarum as a fish pathogen: virulence factors, diagnosis and prevention

Vibrio anguillarum, also known as Listonella anguillarum, is the causative agent of vibriosis, a deadly haemorrhagic septicaemic disease affecting various marine and fresh/brackish water fish, bivalves and crustaceans. In both aquaculture and larviculture, this disease is responsible for severe economic losses worldwide. Because of its high morbidity and mortality rates, substantial research has been carried out to elucidate the virulence mechanisms of this pathogen and to develop rapid detection techniques and effective disease‐prevention strategies. This review summarizes the current state of knowledge pertaining to V. anguillarum, focusing on pathogenesis, known virulence factors, diagnosis, prevention and treatment.     

Note on the transmission of Theileria annulata by Hyalomma ticks in the Sudan

Nymphs of Hyalomma impeltatum and H. dromedarii, fed as larvae on an infected calf transmitted fatal Theileria annulata infection to two susceptible calves. The significance of these findings is discussed in relation to the epidemiology of tropical theileriosis in the Sudan.     

Biosocial and bionumerical diversity of variously sized home gardens in Tabasco, Mexico

The evaluation of species and structural diversity of home gardens strongly depends on the methods used. We distinguish the biosocial and the bionumerical method. The first is widely used and takes data of the whole population of trees of home gardens to calculate diversity. The bionumerical method calculates diversity from data of a fixed number of randomly selected trees. We apply both methods to analyze if structural and species diversity varies with home garden size, a theme of considerable conservation interest, and compare results. We inventoried the tree component of a sample of 61 home gardens from rural areas in Tabasco, Mexico, which we assigned to three size categories: small (≤1,000 m²), medium sized (>1,000 and ≤2,000 m²), and large home gardens (>2,000 m²). Average species richness and Shannon diversity indices determined by the biosocial method were significantly different among home garden size classes. Average species richness determined by the bionumerical method did not differ among size classes. Both methods showed highest total observed and estimated species richness in the large home gardens, which contain many unique species. Both methods showed similar overall species composition among size classes and highest structural diversity in large home gardens. We conclude that it is important for conservation to maintain large home gardens in local mosaics, and that the biosocial and bionumerical methods are complementary. The bionumerical method allows straight comparison of population diversity within and among systems, but lacks attention for rare and unique species. The biosocial method evaluates how much diversity families custody.     

Farming ethics in practice: from freedom to professional moral autonomy for farmers

Food production, water management, land use, and animal and public health are all topics of extensive public debate. These themes are linked to the core activities of the agricultural sector, and more specifically to the work of farmers. Nonetheless, the ethical discussions are mostly initiated by interest groups in society rather than by farmers. At least in Europe, consumer organizations and animal welfare and environmental organizations are more present in the public debate than farmers. This is not how it should be. First, because consumers often cannot but rely on agriculture. Second, because recent research shows that farmers have moral beliefs and convictions that appear to be broader than economic considerations and that are—to a certain extent—specific to their profession. This raises the question how to make input from farmers operational in the public debates on the future of farming. We discuss one option: entrusting farmers with professional autonomy concerning moral matters related to farming. We sketch the historical background of the current situation in which farmers are relatively silent on moral matters and we present some clear indications that farmers have values and moral beliefs that are relevant for the public debate. Next the concepts of professionalism and professional autonomy are discussed and applied to the practice of farming. Finally, we discuss the relevance and limits of professional moral autonomy for the agricultural profession. We close with an overview of what this moral autonomy implies for and requires from farmers in practice. We conclude that if some preconditions are met by farmers, then this type of moral autonomy can be relevant for farmers and for society, and contributes to the quality of the public debate on the future of farming.     

Prevalence of Coxiella burnetii in ticks after a large outbreak of Q fever

Q fever has emerged as an important human and veterinary public health problem in the Netherlands with major outbreaks in three consecutive years. Goat farms are probably the prime source from which Coxiella burnetii have spread throughout the environment, infecting people living in the vicinity. Coxiella burnetii infection not only spilled over from animal husbandry to humans but could also have spread to neighbouring wildlife and pets forming novel reservoirs and consequently posing another and lingering threat to humans, companion animals and livestock. In these cases, transmission routes other than airborne spread of contaminated aerosols may become significant. Therefore, the role of ticks in the transmission of Coxiella burnetii in the current situation was investigated. A total of 1891 questing Ixodes ricinus ticks and 1086 ticks feeding on pets, wildlife and livestock were tested by a recently developed multiplex Q-PCR. All ticks were negative, except for a few ticks feeding on a herd of recently vaccinated sheep. Coxiella-positive ticks were not detected after resampling this particular herd three months later. Based on these data we conclude that the current risk of acquiring Q fever from questing ticks in the Netherlands is negligible. However, for future risk assessments, it might be relevant to sample more ticks in the vicinity of previously C. burnetii infected goat farms and to assess whether C. burnetii can be transmitted transovarially and transstadially in I. ricinus ticks.     

Mechanisms controlling the oxygen consumption in experimentally induced hypochloremic alkalosis in calves

The study was carried out on healthy Friesian calves (n = 10) aged between 10 and 30 days. Hypochloremia and alkalosis were induced by intravenous administration of furosemide and isotonic sodium bicarbonate. The venous and arterial blood samples were collected repeatedly. 2,3-diphosphoglycerate (2,3-DPG), hemoglobin and plasmatic chloride concentrations were determined. The red blood cell chloride concentration was also calculated. pH, PCO2 and PO2 were measured in arterial and mixed venous blood. The oxygen equilibrium curve (OEC) was measured in standard conditions. The correspondence of the OEC to the arterial and mixed venous compartments was calculated, taking blood temperature, pH and PCO2 values into account. The oxygen exchange fraction (OEF%), corresponding to the degree of blood desaturation between the arterial and mixed venous compartments and the amount of oxygen released at the tissue level by 100 mL of blood (OEF Vol%) were calculated from the arterial and mixed venous OEC, combined with PO2 and hemoglobin concentration. Oxygen delivery (DO2) was calculated using the arterial oxygen content, the cardiac output measured by thermodilution, and the body weight of the animal. The oxygen consumption (VO2) was derived from the cardiac output, OEF Vol% and body weight values. Despite the plasma hypochloremia, the erythrocyte chloride concentration was not influenced by furosemide and sodium bicarbonate infusion. Due to the alkalosis-induced increase in the 2,3-DPG, the standard OEC was shifted to the right, allowing oxygen to dissociate from hemoglobin more rapidly. These changes opposed the increased affinity of hemoglobin for oxygen induced by alkalosis. Moreover, respiratory acidosis, hemoconcentration, and the slight decrease in the partial oxygen pressure in mixed venous blood (Pvo2) tended to improve the OEF Vol% and maintain the oxygen consumption in a physiological range while the cardiac output, and the oxygen delivery were significantly decreased. It may be concluded that, despite reduced oxygen delivery, oxygen consumption is maintained during experimentally induced hypochloremic alkalosis in healthy 10-30 day old calves.     

Seasonal epidemiology of ticks and aspects of cowdriosis in N'Dama village cattle in the Central Guinea savannah of Côte d'Ivoire

In the Central Guinea savannah of C?te d'Ivoire, cattle breeding started only approximately 30 years ago. The impact of parasitism on the overall health status and productivity of the trypanotolerant N'Dama cattle in this area is unknown. In close collaboration with national veterinary institutions and local farmers, we studied spectrum, burden and seasonal dynamics of ticks (including aspects of cowdriosis) on N'Dama village cattle. In a longitudinal study, three randomly selected cattle herds (traditional farming type) of one village were examined repeatedly for ticks. Spectrum, burden, seasonal epidemiology of ticks were assessed. In these traditional herds (which lack (ecto)parasite management), all animals were infested by ticks at monthly counts. Five different tick species were identified; the four genera in order of frequency were: Amblyomma (overall prevalence 96%), Boophilus (47%), Hyalomma (<1%) and Rhipicephalus (<1%). Amblyomma variegatum was the most-abundant tick on cattle in all seasons. Seroprevalence of Cowdria ruminantium was 31% (95% CI: 26, 36%). Most of the animals typically carried low tick burdens. N'Dama cattle seem well adapted to their environment and can resist the tick burdens under this traditional farming system.     

Blood oxygen binding in hypoxaemic calves

Blood oxygen transport and tissue oxygenation were studied in 28 calves from the Belgian White and Blue breed (20 healthy and 8 hypoxaemic ones). Hypoxaemic calves were selected according to their high respiratory frequency and to their low partial oxygen pressure (PaO2) in the arterial blood. Venous and arterial blood samples were collected, and 2,3-diphosphoglycerate, adenosine triphosphate, chloride, inorganic phosphate and hemoglobin concentrations, and pH, PCO, and PO2 were determined. An oxygen equilibrium curve (OEC) was measured in standard conditions, for each animal. The arterial and venous OEC were calculated, taking body temperature, pH and PCO2 values in arterial and venous blood into account. The oxygen exchange fraction (OEF%), corresponding to the degree of blood desaturation between the arterial and the venous compartments, and the amount of oxygen released at the tissue level by 100 mL of blood (OEF Vol%) were calculated from the arterial and venous OEC combined with the PO2 and hemoglobin concentration. In hypoxaemic calves investigated in this study, the hemoglobin oxygen affinity, measured under standard conditions, was not modified. On the contrary, in vivo acidosis and hypercapnia induced a decrease in the hemoglobin oxygen affinity in arterial blood, which combined to the decrease in PaO2 led to a reduced hemoglobin saturation degree in the arterial compartment. However, this did not impair the oxygen exchange fraction (OEF%), since the hemoglobin saturation degree in venous blood was also diminished.