Livestock Husbandry between Ethics and Economics: Finding a Feasible Way Out by Target Costing?

Livestock husbandry is a major line of conflict in many industrialized countries. Farmers are caught in a dilemma between ethical considerations imposed by, for instance, nongovernmental organizations and the wider public on the one hand and competitive and economic pressures on the other. In this paper we use a target-costing approach to determine whether it is possible to implement more animal-friendly husbandry conditions for turkey fattening in Germany without sacrificing competitiveness. Empirical results show that, at first glance, the willingness on the part of consumers to pay for more animal welfare exceeds the costs to farmers of more animal-friendly husbandry systems. A critical discussion reveals that this result may be flawed by methodological problems for which no solutions have yet been found.animal welfare, livestock husbandry, target costing, willingness to pay, Livestock Production/Industries, D12, D63, Q12,

Nicht zu vergessende Moleküle ... : flexibles "Networking" von Nervenzellen formt das Gedächtnis

Ein funktionierendes Gedächtnis beruht darauf, dass die Kontakte zwischen den Milliarden Nervenzellen in unserem Gehirn sich ständig verändern und anpassen. Häufig verwendete Signalwege werden verstärkt und ausgebaut, wie eine Landstraße zu einer Schnellstraße. Weniger häufig benutze Signalwege können dagegen abgebaut werden. Die Signalübertragung verlangsamt sich wie der Verkehr auf einer lange nicht mehr instand gehaltenen Straße. Will man diese Prozesse auf molekularer Ebene verstehen, muss man die Synapsen näher betrachten. Das sind spezialisierte Kontaktstellen, die es den Nervenzellen ermöglichen, hochkomplexe Netzwerke, sogenannte Schaltkreise, zu knüpfen. Die Flexibilität dieser Schaltkreise ermöglicht es uns, Informationen zu verarbeiten und entsprechend zu reagieren. Inzwischen kennt man eine Fülle von Boten-Molekülen, Rezeptoren und Liganden, die diese Prozesse auf molekularer Ebene steuern

Investigation of the Spark channel of Electrical Discharges Near the Minimum Ignition Energy

In this work, we investigate the expansion of the hot gas kernel and pressure wave induced by electrical discharges near the minimum ignition energy experimentally by means of a schlieren setup and numerically through one-dimensional simulations. The effects of discharge energy and energy density on the expansion are discussed. Via comparison of experimental values with numerical simulations, an estimate of the overall losses of the discharge is presented

Experimental investigation of the stochastic early flame propagation after ignition by a low-energy electrical discharge

In the context of explosion protection, very conservative safety factors need to be considered, e.g. in the design of electrical devices. This is due to standards which are mainly based on empirical data as opposed to a detailed knowledge of the underlying physiochemical processes. In this work, the early phase of ignition of burnable gas mixtures close to their respective minimum ignition energy is investigated experimentally by means of high-speed schlieren imaging. Our data quantifies how the ignition process at such low energies becomes less repeatable which is evidenced by a high scattering of the flame propagation. It was found that, depending on the mixture, the flow field induced by the electrical discharge may exhibit a considerable effect on the ignition process. This effect is more pronounced for mixtures which are characterized by a large Lewis number, thus, leading to a more random flame propagation

Surface modifying substances that reduce apparent yeast cell hydrophobicity.

OBJECTIVE: To determine whether several topical compounds and other chemical entities are able to diminish the surface hydrophobicity of yeast cells. METHOD: Hydrophobicity of yeast cells was determined by binding styrene microspheres to the surface of untreated yeast or yeast pre-incubated with various substances with potential for cell surface modification. The degree of microsphere adherence to yeast cells was measured by flow cytometry. RESULTS: A significant reduction in cell surface hydrophobicity was observed when yeast was incubated in protein-containing media. Other compounds that effectively reduced microsphere binding were various formulations of K-Y and heparin. Divalent cations (Ca+ + , Mg+ + , Zn+ + , Cu + + ) were also potent inhibitors of microsphere adherence. It was possible to remove substances contributing to microsphere binding by chemical extraction of the yeast. Yeast having reduced microsphere binding activity also showed diminished binding of concanavalin A. CONCLUSIONS: Several commercially available compounds were able to block binding of styrene microspheres to yeast. Some of the binding activity appeared to be attributable to mannose-containing surface components. These findings have implications for formulating therapeutic products that might block yeast binding to tissues

Tetracycline Effects on Candida Albicans Virulence Factors

Object. To determine if tetracycline, previously reported to increase the probability of developing symptomatic vaginal yeast infections, has a direct effect on Candida albicans growth or induction of virulent phenotypes. Method. In vitro, clinical isolates of yeast were cultivated with sublethal concentrations of tetracycline and yeast cell counts, hyphal formation, drug efflux pump activity, biofilm production, and hemolysin production were determined by previously reported methods. Results. Tetracycline concentrations above 150 μg/mL inhibited Candida albicans, but at submicrogram/mL, a modest growth increase during the early hours of the growth curve was observed. Tetracycline did not inhibit hyphal formation at sublethal concentrations. Hypha formation appeared augmented by exposure to tetracycline in the presence of chemically defined medium and especially in the presence of human serum. Efflux pump CDR1 was upregulated and a nonsignificant trend toward increased biofilm formation was noted. Conclusion. Tetracycline appears to have a small growth enhancing effect and may influence virulence through augmentation of hypha formation, and a modest effect on drug efflux and biofilm formation, although tetracycline did not affect hemolysin. It is not clear if the magnitude of the effect is sufficient to attribute vaginitis following tetracycline treatment to direct action of tetracycline on yeast

Adherence and Blocking of Candida Albicans to Cultured Vaginal Epithelial Cells: Treatments to Decrease Adherence

Background. Pathogenesis of mucosal microorganisms depends on adherence to the tissues they colonize and infect. For Candida albicans, cell surface hydrophobicity may play a significant role in tissue binding ability. Methods. A continuous cell line of vaginal epithelial cells (VEC) was grown in keratinocyte serum-free medium (KSFM) with supplements and harvested by trypsinization. VEC were combined with yeast cells to evaluate adherence and inhibition of adherence. In this experimental setup, yeast stained with fluorescein isothiocyanate were allowed to attach to VEC and the resulting fluorescent VEC were detected by flow cytometry. Results. VEC were cultured and examined daily after plating and showed morphology similar to basal epithelial cells. Culture media supplemented with estradiol showed increased VEC proliferation initially (first 24 h) but cell morphology was not altered. Fluorescinated Candida cells bound effectively to the cultured VEC. Using fresh cells exposed to various preparations of K-Y, we showed that all formulations of the product reduced Candida binding to VEC by 25% to 50%. While VEC were generally harvested for use in experiments when they were near confluent growth, we allowed some cultures to grow beyond that point and discovered that cells allowed to become overgrown or stressed appeared to bind yeast cells more effectively. Conclusion. Flow cytometry is a useful method for evaluating binding of stained yeast cells to cultured VEC and has demonstrated that commercially available products have the ability to interfere with the process of yeast adherence to epithelial cells

Candidiasis During Pregnancy May Result From Isogenic Commensal Strains

Objective: Our laboratory previously demonstrated that asymptomatic vaginal colonization during pregnancy is a factor predisposing patients to subsequent symptomatic vulvovaginal candidiasis. It is unknown whether symptoms result from strain replacement or a change in host relationship to the original colonizing strain. This study was undertaken to determine whether Candida albicans isolates from asymptomatic women could be responsible for subsequent symptomatic vaginitis. Methods: We retained isolates of C. albicans from women followed longitudinally through pregnancy, and identified six pairs of cultures from women who were colonized without symptoms and who later became symptomatic (average time 14 weeks). We used a random amplification of polymorphic DNA (RAPD) analysis to determine whether isolates from our study patients were genetically similar or dissimilar. Results: Analysis of these pairs of yeast strains by RAPD revealed that five of the six women had symptoms apparently due to the same yeast strain that was found initially as a commensal strain. To increase the power of these observations, we also performed RAPD analysis on six randomly selected yeast strains from other women in this study who had not become symptomatic to determine whether any of these unrelated strains matched strains from those women who became symptomatic. Conclusion: Symptomatic yeast vaginitis is usually due to strains of C. albicans already carried in the lower genital tract, underscoring the need to understand regulation of growth and virulence of the organism in vivo

Evaluation of relative yeast cell surface hydrophobicity measured by flow cytometry.

OBJECTIVE: To develop an efficient method for evaluating cell surface hydrophobicity and to apply the method to demonstrate the effects of fungal growth conditions on cell surface properties. METHODS: Yeast isolates were suspended in phosphate-buffered saline and mixed with deep blue-dyed polystyrene microspheres. Flow cytometry was used to detect the degree of microsphere binding to yeast cells. Different strains of yeast were compared for intrinsic microsphere binding activity and changes in growth conditions were invoked to modify the relative surface hydrophobicity. RESULTS: Commercially available blue-dyed polystyrene microspheres showed strong fluorescence in the FL3 channel, whereas yeast cells did not show appreciable FL3 fluorescence. Microspheres and yeast were generally distinguishable on the basis of size revealed by forward light scatter. This method showed a wide variation in intrinsic cell surface hydrophobicity among Candida albicans strains. Likewise, variation in hydrophobicity of non-albicans yeast species was observed. Growth on solid media, incubation at 25 degrees C, or 250 mg/dl glucose concentration increased hydrophobicity compared with growth in liquid media, incubation at 37 degrees C, or 50 mg/dl glucose, respectively. Growth in 1 x 10(-9) M estradiol had no appreciable effect on hydrophobicity. CONCLUSIONS: Stained latex microspheres fluoresced in the FL3 channel of the flow cytometer and bound to yeast cells to an extent related to the surface hydrophobicity of the yeast. Binding detected by flow cytometry showed that clinical yeast isolates varied in intrinsic binding capacity and this binding ability was altered by different growth conditions. The implications for virulence regulation among yeast isolates are discussed

Complex dynamics of solid-fluid systems

The focus of this thesis was the investigation of the complex dynamics of solid-fluid systems. These systems are of great industrial importance, such as in methane clathrate formation in sub-sea pipelines. As well as being crucial to furthering our understanding of various natural phenomena, such as the rate of rain droplet formation in clouds. We began by considering the problem of the orbits tracked by ellipsoids immersed in viscous and inviscid environments. This investigation was carried out by a combination of analytical and numerical techniques: direct numerical simulations of resolved full-coupled solid-fluid systems, analysis the Kirchhoff-Clebsch equations for the case of inviscid flows, and characterising dynamics through advanced techniques such as recurrence quantification analysis. We demonstrate that the ellipsoid tracks a chaotic orbit not only in an inviscid environment but also when submerged in a viscous fluid, under specific conditions. Under inviscid environments, an ellipsoid subject to arbitrary initial conditions of linear and angular momentum demonstrates chaotic orbits when all the three axes of the ellipsoid are unequal, in agreement with the Kozlov and Onishchenko’s theorem of non-integrability of Kirchhoff’s equations and also with Aref and Jones’s potential flow solution. We then extended our methodology to understand the dynamics of a single ellipsoid tumbling in a viscous environment with the presence of both passive and viscosity coupled tracers in addition to the chaotic dynamics predicted by the Kirchhoff-Clebsch equations. Our results show that the bodies move along from viscosity gradients towards minima of the viscous stress. These bodies might become trapped in unstable minima. However, more work is needed to understand the long-term mixing of viscosity coupled tracers. Our direct numerical solver was also extended to include contact models for solid-solid interactions in the simulation domain. The validation of the contact models was presented. Finally, we expand, the theoretical framework of the Kirchhoff-Clebsch equations to account for the presence of multiple bodies. This extension was done by using Hamiltonian mechanics to extend the derivation proposed by Lamb. We present our preliminary result of simulating two solids systems using the extended Kirchhoff-Clebsch equations. The rel- ative orientations of the two solids were found to regularly switch from being correlated to anti-correlated in an otherwise chaotic system. Further work is required to understand the mechanism behind this behaviour