Organic poultry farming

The development in organic livestock production can be attributed to an increased consumer inter-est in organic products while, at the same time, farmers are interested in converting to organic pro-duction methods – often stimulated by governmental support or subsidies. It is important that the organic production systems can fulfil the expectations of each of these stakeholders if the organic livestock production is to increase further. This is in particular important if the organic poultry pro-duction should move from the present niche-production to a real player in the food marked, like in the case of beef and milk. It can be argued that the limited organic poultry production is related to the fact that it is far more difficult for the farmers to change the existing production systems for poultry compared to produc-tion systems for cattle and other ruminants in a way that gives a harmonious balance between the different aims of organic farming. In the existing systems for layers with flock sizes of 3,000 hens and where the hens have access to an outdoor area, the egg production and the feed conversion can be close to production results in conventional production. However, often a considerable mortality can be seen in organic egg production in part due to cannibalism and often also very high nutrient loads are observed in parts of the outdoor area. These conditions are important drawbacks in exist-ing systems. In order to improve the situation there is a need to look at the genotype of hens, to consider new management procedures, and – not at least – to consider new systems where the poultry to a higher degree are integrated in the land use. Promising results with integration of chickens, ducks and geese into an orchard production is found. Also preliminary results of housing systems for small flocks of layers are presented

A cautionary note on robust covariance plug-in methods

Many multivariate statistical methods rely heavily on the sample covariance matrix. It is well known though that the sample covariance matrix is highly non-robust. One popular alternative approach for "robustifying" the multivariate method is to simply replace the role of the covariance matrix with some robust scatter matrix. The aim of this paper is to point out that in some situations certain properties of the covariance matrix are needed for the corresponding robust "plug-in" method to be a valid approach, and that not all scatter matrices necessarily possess these important properties. In particular, the following three multivariate methods are discussed in this paper: independent components analysis, observational regression and graphical modeling. For each case, it is shown that using a symmetrized robust scatter matrix in place of the covariance matrix results in a proper robust multivariate method.Comment: 24 pages, 7 figure

Deterministic multi-mode photonic device for quantum information processing

We propose the implementation of a light source, which can deterministically generate a rich variety of multi-mode quantum states. The desired states are encoded in the collective population of different ground hyperfine states of an atomic ensemble and converted to multi-mode photonic states by excitation to optically excited levels followed by cooperative spontaneous emission. Among our examples of applications, we demonstrate how two-photon entangled states can be prepared and implemented in a protocol for reference frame free quantum key distribution and how one-dimensional as well as higher-dimensional cluster states can be produced.Comment: 5 pages, 4 figure

Atomic spin squeezing in an optical cavity

We consider squeezing of one component of the collective spin vector of an atomic ensemble inside an optical cavity. The atoms interact with a cavity mode, and the squeezing is obtained by probing the state of the light field that is transmitted through the cavity. Starting from the stochastic master equation, we derive the time evolution of the state of the atoms and the cavity field, and we compute expectation values and variances of the atomic spin components and the quadratures of the cavity mode. The performance of the setup is compared to spin squeezing of atoms by probing of a light field transmitted only once through the sample.Comment: 8 pages, 2 figure

Multimode analysis of the light emitted from a pulsed optical parametric oscillator

We present a multimode treatment of the optical parametric oscillator, which is valid for both pulsed and continuous-wave pump fields. The two-time correlation functions of the output field are derived, and we apply the theory to analyze a scheme for heralded production of non-classical field states that may be subsequently stored in an atomic quantum memory.Comment: 11 pages, 6 figure

A Review of Hadronic and Rare B Decays

We review recent experimental results on B meson decays. These include measurements of the inclusive production of charmed and non-charmed mesons and baryons, the reconstruction of a large number of exclusive hadronic final states with charmed mesons, the search for exclusive hadronic final states without charmed mesons, and the first observation of the decay B-> K* gamma which is described by an electromagnetic penguin diagram. The theoretical implications of these results will be considered. The figures can be obtained in postscript format EMAIL from [email protected]: 77 pages; CLNS 93/1261, UH-511-778-93, OHSTPY-HEP-E-93-018, HEPSY 93-1

Measurement-induced two-qubit entanglement in a bad cavity: Fundamental and practical considerations

An entanglement-generating protocol is described for two qubits coupled to a cavity field in the bad-cavity limit. By measuring the amplitude of a field transmitted through the cavity, an entangled spin-singlet state can be established probabilistically. Both fundamental limitations and practical measurement schemes are discussed, and the influence of dissipative processes and inhomogeneities in the qubits are analyzed. The measurement-based protocol provides criteria for selecting states with an infidelity scaling linearly with the qubit-decoherence rate.Comment: 13 pages, 7 figures, submitted to Phys. Rev.