PathOrganic - Identification of Critical Control Points for organic vegetable crops

The aim of this work is the identification of Critical Control Points1 (CCPs) for organic farms, which use manure for the production of organic lettuce, cabbage, carrots and spinach in Austria, Switzerland, Sweden, and Denmark. Due to the application of manure, vegetables are at risk to be contaminated with enteropathogens such as Escherichia coli pathogenic strains (i. e. O157:H7), Salmonella enterica serovar Typhimurium, Campylobacter jejuni, Listeria monocyto-genes, and Staphylococcus aureus. This work applies part of the principles and steps described for HACCP2 to identify the CCPs. The steps described hereafter are reported in the course guidance document “HACCP in agri-culture – Organic milk production” (1) and were adapted to the agricultural production of field vegetables. The hazard analysis is based on the characteristics of the above mentioned enteropathogens and the agricultural practices applied by the organic farmers in the four countries when growing lettuce, cabbage, carrots, and spinach. The assessment of the actual agricultural practices uses the evaluation of interviews conducted with organic farmers growing these vegetables and using manure as fertiliser. In total were interviewed 16 farmers in Austria, 16 farmers in Switzerland, 13 farmers in Sweden, and 9 farmers in Denmark. In general terms, there is no agricultural practice common to the majority of organic farmers concerning the management of animal ma-nure, fertilisation, irrigation, harvest and postharvest management when growing lettuce, cab-bage, spinach, and carrots in Austria, Switzerland, Denmark, and Sweden. Using the decision tree of the HACCP system, CCPs were identified for the primary production of organic field vegetables. Where appropriate, instead of CCPs were defined PRP-CPs3 or OP-PRPs4. Four CCPs were identified for the process steps ‘storage of animal manure’, ‘fertilisation practices’, ‘prevention of runoff and flooding’, and ‘irrigation practices’

On the linear dispersion--linear potential quantum oscillator

We solve the bi-linear quantum oscillator H=v|p|+F|x| both quasi-classically and numerically.Comment: 5 pages, 3 figure

Gauge invariance and wave packet simulations in the presence of dipole fields

A method for performing wave packet simulations in dipole fields is presented. Starting from a Hamiltonian with non commuting terms, a gauge transformation leads to a new Hamiltonian which allows to calculate explicitly the evolution operator. In this new gauge, the dipole field is fully included in the {\it vector} potential. The method of Goldberg, Schwartz and Schey based on the Caley form of the evolution operator is then generalized, and the resulting scheme is applied to describe a switching device based on Rabi oscillations. The probability to tunnel in the free region exhibits a plateaux structure as the wave function is emitted by ``bursts'' after each Rabi oscillation has been completed.Comment: 4 pages (Revtex 3.0), figures upon request, LA-UR-94-303

Spheroidal nanoparticles as thermal near-field sensors

We suggest to exploit the shape-dependence of the near-field heat transfer for nanoscale thermal imaging. By utilizing strongly prolate or oblate nanoparticles as sensors one can assess individual components of the correlation tensors characterizing the thermal near field close to a nanostructured surface, and thus obtain directional information beyond the local density of states. Our theoretical considerations are backed by idealized numerical model calculations

Scattering of electromagnetic waves by many thin cylinders

Electromagnetic wave scattering by many parallel infinite cylinders is studied asymptotically as $a\to 0$. Here $a$ is the radius of the cylinders. It is assumed that the points $\hat{x}_m$ are distributed so that $\mathcal{N}(\Delta)=\frac{1}{a}\int_{\Delta}N(x)dx[1+o(1)],$ where $\mathcal{N}(\Delta)$ is the number of points $\hat{x}_m=(x_{m1},x_{m2})$ in an arbitrary open subset of the plane $xoy$, the axes of the cylinders are passing through points $\hat{x}_m$, these axes are parallel to the z-axis. The function $N(x)\geq 0$ is a given continuous function. An equation for the self-consistent (efficient) field is derived as $a\to 0$. The cylinders are assumed perfectly conducting. Formula is derived for the effective refraction coefficient in the medium in which many cylinders are distributed

γ\gamma - Z interferometry at a Φ\Phi-factory

We analyze the possibilities that the proposed $\Phi$-factories offer to measure $\gamma-Z$ interference. In the unpolarized beam case, we study different signatures in the $\rho \pi$ channel, taking advantage of the presence of the near-by $a_1$ resonance. We build a C-odd forward-backward asymmetry, estimated to be around $10^{-5}$, and (P-even, T-even) and (P-odd, T-odd) alignments of the $\rho$, to be seen from the angular distribution of its $\pi \pi$ decay products. With polarized electrons a left-right asymmetry around $2\times 10^{-4}$ is present in all channels. At leading order this asymmetry is independent of hadronic matrix elements and is sensitive to the $Z^0-s\bar{s}$ vector coupling. In the $\rho \pi$ channel, a combined left-right forward-backward asymmetry is considered.Comment: 29 pages + 6 figures. Some changes concerning $a_1$ observables, especially related with possible 2 $\gamma$ contribution

Statistical Error in Particle Simulations of Hydrodynamic Phenomena

We present predictions for the statistical error due to finite sampling in the presence of thermal fluctuations in molecular simulation algorithms. Specifically, we establish how these errors depend on Mach number, Knudsen number, number of particles, etc. Expressions for the common hydrodynamic variables of interest such as flow velocity, temperature, density, pressure, shear stress and heat flux are derived using equilibrium statistical mechanics. Both volume-averaged and surface-averaged quantities are considered. Comparisons between theory and computations using direct simulation Monte Carlo for dilute gases, and molecular dynamics for dense fluids, show that the use of equilibrium theory provides accurate results.Comment: 24 pages postscript (including 16 figures

Attitudes toward conflict and aggression

Depto. de Psicobiología y Metodología en Ciencias del ComportamientoFac. de PsicologíaTRUEpu

Topology induced anomalous defect production by crossing a quantum critical point

We study the influence of topology on the quench dynamics of a system driven across a quantum critical point. We show how the appearance of certain edge states, which fully characterise the topology of the system, dramatically modifies the process of defect production during the crossing of the critical point. Interestingly enough, the density of defects is no longer described by the Kibble-Zurek scaling, but determined instead by the non-universal topological features of the system. Edge states are shown to be robust against defect production, which highlights their topological nature.Comment: Phys. Rev. Lett. (to be published

Gravitational radiation from monopoles connected by strings

Monopole-antimonopole pairs connected by strings can be formed as topological defects in a sequence of cosmological phase transitions. Such hybrid defects typically decay early in the history of the universe but can still generate an observable background of gravitational waves. We study the spectrum of gravitational radiation from these objects both analytically and numerically, concentrating on the simplest case of an oscillating pair connected by a straight string.Comment: 18 pages, RevTex and 2 postscript figures. Submitted to Phys. Rev.