Combining Ethological Thinking and Epidemiological Knowledge to Enhance the Naturalness of Organic Livestock Systems

Organic livestock farming places strong emphasis on conditions that allow animals to exhibit behavioural needs. This involves the provision of a natural environment and, in particular, outdoor conditions and a reliance on natural forages. Such environments also allow animals to be effectively integrated into crop production. However, there are potential disease risks associated with these conditions, with control options being partly limited by restrictions on chemoprophylactic measures. Examples from dairy and poultry production demonstrate how a basic understanding of ethology and a knowledge of disease epidemiology can enhance the welfare of animals whilst satisfying the ecological objectives of organic farming. Existing epidemiological models and published data can be used to examine the potential ensuing health hazards and control possibilities and to suggest alternatives

Scattering of dislocated wavefronts by vertical vorticity and the Aharonov-Bohm effect II: Dispersive waves

Previous results on the scattering of surface waves by vertical vorticity on shallow water are generalized to the case of dispersive water waves. Dispersion effects are treated perturbatively around the shallow water limit, to first order in the ratio of depth to wavelength. The dislocation of the incident wavefront, analogous to the Aharonov-Bohm effect, is still observed. At short wavelengths the scattering is qualitatively similar to the nondispersive case. At moderate wavelengths, however, there are two markedly different scattering regimes according to wether the capillary length is smaller or larger than $\sqrt{3}$ times depth. The dislocation is characterized by a parameter that depends both on phase and group velocity. The validity range of the calculation is the same as in the shallow water case: wavelengths small compared to vortex radius, and low Mach number. The implications of these limitations are carefully considered.Comment: 30 pages, 11 figure

Scattering of second sound waves by quantum vorticity

A new method of detection and measurement of quantum vorticity by scattering second sound off quantized vortices in superfluid Helium is suggested. Theoretical calculations of the relative amplitude of the scattered second sound waves from a single quantum vortex, a vortex ring, and bulk vorticity are presented. The relevant estimates show that an experimental verification of the method is feasible. Moreover, it can even be used for the detection of a single quantum vortex.Comment: Latex file, 9 page

Registration of the First Thermonuclear X-ray Burst from AX J1754.2-2754

During the analysis of the INTEGRAL observatory archival data we found a powerful X-ray burst, registered by JEM-X and IBIS/ISGRI telescopes on April 16, 2005 from a weak and poorly known source AX J1754.2-2754. Analysis of the burst profiles and spectrum shows, that it was a type I burst, which result from thermonuclear explosion on the surface of nutron star. It means that we can consider AX J1754.2-2754 as an X-ray burster. Certain features of burst profile at its initial stage witness of a radiation presure driven strong expansion and a corresponding cooling of the nutron star photosphere. Assuming, that the luminosity of the source at this phase was close to the Eddington limit, we estimated the distance to the burst source d=6.6+/-0.3 kpc (for hidrogen atmosphere of the neutron star) and d=9.2+/-0.4 kpc (for helium atmosphere).Comment: 12 pages, 6 figure

Topological Landau-Ginzburg Theory for Vortices in Superfluid 4^4He

We propose a new Landau-Ginzburg theory for arbitrarily shaped vortex strings in superfluid $^4$He. The theory contains a topological term and directly describes vortex dynamics. We introduce gauge fields in order to remove singularities from the Landau-Ginzburg order parameter of the superfluid, so that two kinds of gauge symmetries appear, making the continuity equation and conservation of the total vorticity manifest. The topological term gives rise to the Berry phase term in the vortex mechanical actions.Comment: LATEX, 9 page

New Approximability Results for the Robust k-Median Problem

We consider a robust variant of the classical $k$-median problem, introduced by Anthony et al. \cite{AnthonyGGN10}. In the \emph{Robust $k$-Median problem}, we are given an $n$-vertex metric space $(V,d)$ and $m$ client sets $\set{S_i \subseteq V}_{i=1}^m$. The objective is to open a set $F \subseteq V$ of $k$ facilities such that the worst case connection cost over all client sets is minimized; in other words, minimize $\max_{i} \sum_{v \in S_i} d(F,v)$. Anthony et al.\ showed an $O(\log m)$ approximation algorithm for any metric and APX-hardness even in the case of uniform metric. In this paper, we show that their algorithm is nearly tight by providing $\Omega(\log m/ \log \log m)$ approximation hardness, unless ${\sf NP} \subseteq \bigcap_{\delta >0} {\sf DTIME}(2^{n^{\delta}})$. This hardness result holds even for uniform and line metrics. To our knowledge, this is one of the rare cases in which a problem on a line metric is hard to approximate to within logarithmic factor. We complement the hardness result by an experimental evaluation of different heuristics that shows that very simple heuristics achieve good approximations for realistic classes of instances.Comment: 19 page

Evidence for 1122 Hz X-Ray Burst Oscillations from the Neutron-Star X-Ray Transient XTE J1739-285

We report on millisecond variability from the X-ray transient XTE J1739-285. We detected six X-ray type I bursts and found evidence for oscillations at 1122 +/- 0.3 Hz in the brightest X-ray burst. Taking into consideration the power in the oscillations and the number of trials in the search, the detection is significant at the 99.96% confidence level. If the oscillations are confirmed, the oscillation frequency would suggest that XTE J1739-285 contains the fastest rotating neutron star yet found. We also found millisecond quasiperiodic oscillations in the persistent emission with frequencies ranging from 757 Hz to 862 Hz. Using the brightest burst, we derive an upper limit on the source distance of about 10.6 kpc.Comment: To appear in ApJL, 4 page

Systematic trends in beta-delayed particle emitting nuclei: The case of beta-p-alpha emission from 21Mg

We have observed beta+-delayed alpha and p-alpha emission from the proton-rich nucleus 21Mg produced at the ISOLDE facility at CERN. The assignments were cross-checked with a time distribution analysis. This is the third identified case of beta-p-alpha emission. We discuss the systematic of beta-delayed particle emission decays, show that our observed decays fit naturally into the existing pattern, and argue that the patterns are to a large extent caused by odd-even effects.Comment: 6 pages, 5 figure

Impact of Rubin Observatory LSST Template Acquisition Strategies on Early Science from the Transients and Variable Stars Science Collaboration: Non-time-critical Science Cases

Vera C. Rubin Observatory Legacy Survey of Space and Time, LSST, will revolutionize modern astronomy by producing an extremely deep (coadded depth ~27 mag) depth-limited survey of the entire southern sky (LSST Science Collaboration et al. 2009). The 8.4 m large-aperture, wide-field telescope, which is based in Cerro Pachón, will image the entire Southern sky every three nights in multiple bands (SDSS-u, g, r, i, z, y) and produce a fire-hose of data, 20 Tb each night, concluding in a 60 petabyte data set as the legacy of the 10 yr survey. Extracting meaningful light curves from variable objects requires difference imaging to both identify variability and calibrate light curve data products. Templates, co-added groups of visits that act as an image of the "static" sky, are a key component of Difference Imaging Analysis (DIA) and as such are of paramount importance for all science that involves variable objects. As the "non-time-critical" science cases discussed here are mostly periodic, they generally do not depend upon the survey alert stream; however, templates are still crucial for performing science and calibrations during the first year. We provide recommendations for observing strategies for template acquisition starting from commissioning and through Year 1 of the survey

Concepts of Animal Health and Welfare in Organic Livestock Systems

In 2005, The International Federation of Organic Agricultural Movements (IFOAM) developed four new ethical principles of organic agriculture to guide its future development: the principles of health, ecology, care, and fairness. The key distinctive concept of animal welfare in organic agriculture combines naturalness and human care, and can be linked meaningfully with these principles. In practice, a number of challenges are connected with making organic livestock systems work. These challenges are particularly dominant in immature agro-ecological systems, for example those that are characterized by industrialization and monoculture. Some of the current challenges are partly created by shortages of land and manure, which encourage zero-grazing and other confined systems. Other challenges are created in part by the conditions for farming and the way in which global food distribution systems are organized, e.g., how live animals are transported, how feed is traded and transported all over the globe, and the development of infrastructure and large herds. We find that the overall organic principles should be included when formulating guidelines for practical organic animal farming. This article explores how the special organic conceptions of animal welfare are related to the overall principles of organic agriculture. The aim is to identify potential routes for future development of organic livestock systems in different contexts and with reference to the specific understanding of animal welfare in organic agriculture. We include two contrasting cases represented by organic livestock systems in northwestern Europe and farming systems in tropical low-income countries; we use these cases to explore the widely different challenges of organic livestock systems in different parts of the world