2,686 research outputs found
Mammalian pest problems in organic pig farming, preventive measures and control
Organic pig farming includes having pigs in open fields with relatively close contact to the wild fauna. The risk of transmission of parasites and diseases to the pigs is therefore higher than in traditional pig farming with pigs under strict control in indoor pigsties. Newborn and sucking pigs are also exposed to predators that may cause losses to the farmers.
A general trend in organic farming is to avoid the use of pesticides. There is therefore a need for effective preventive measures and control methods that are acceptable to the organic farmers.
As a first step in a project for developing strategies for pest management in organic pig farming we conducted a questionnaire survey in Denmark. The farmers were asked questions about what they considered problems arising from the natural environment. They were also asked to describe how they offered fodder and water, which types of huts they used etc. The surroundings should be described regarding factors that were thought to influence the natural fauna, such as e.g. distance to quickset hedges, forests, streams and watercourses.
The results of the survey showed that rats and smaller rodents (mice and voles), foxes and hares were the most frequently occurring mammals in the fields with pigs. The farmers considered rats and foxes as causing the most important (pest) problems. Occurrence of rats is reported significantly more frequently in organic pig farming than in traditional pig farming in open fields.
The answers given by the farmers were analysed as to possible relationships between occurrence of / problems with rodents and the practice regarding the pig farming. There was a significant positive correlation between occurrence of rats, smaller rodents and foxes. Use of automatic feeding systems and open water trays, and having stacks of hay and straw in the fields were all factors that were significantly positively correlated with the occurrence of rats and smaller rodents. The occurrence of smaller rodents was negatively correlated with the use of huts with a bottom and huts made of hard materials. Special shelters for the pigs exclusively made of bales of straw did not give a significant positive correlation with occurrence of rodents.
These results indicate factors that are practicable as preventive measures against rodents. The farmers reported traps, shooting, and cats and dogs as the most frequent non-chemical ways of controlling rodents
Gode ideer til giftfri muse- og rottebekæmpelse
I økologisk produktion er det stadig tilladt at anvende antikoagulanter til rottebekæmpelse. Kan brug af kemiske bekæmpelsesmidler i de økologiske bedrifter helt undgås, vil det være i god overensstemmelse med det grundlæggende koncept. Ved avl af frilandsgrise er der yderligere den faktor, at man er meget tættere på den frie natur, så ved brug af kemiske bekæmpelsesmidler har man en potentiel risiko for at påvirke og forgifte ikke-måldyr, altså de dyr der forekommer og ikke optræder som uønskede skadedyr. For at undgå problemer med mus og rotter er de forebyggende foranstaltninger en vigtig forudsætning, og disse skal overvejes både ved etablering og ved den daglige drift. Derved kan den egentlige bekæmpelse begrænses væsentligt
Non-poisonous means for reducing rodent pest problems in organic pig farming
The results indicate factors that are practicable as preventive measures against rodents. Preventive measures are to be considered when planning and laying out the fields for the pigs and when running the farm as well
Evidence for Kosterlitz-Thouless type orientational ordering of CFBr monolayers physisorbed on graphite
Monolayers of the halomethane CFBr adsorbed on graphite have been
investigated by x-ray diffraction. The layers crystallize in a commensurate
triangular lattice. On cooling they approach a three-sublattice
antiferroelectric pattern of the in-plane components of the dipole moments. The
ordering is not consistent with a conventional phase transition, but points to
Kosterlitz-Thouless behavior. It is argued that the transition is described by
a 6-state clock model on a triangular lattice with antiferromagnetic nearest
neighbor interactions which is studied with Monte-Carlo simulations. A
finite-size scaling analysis shows that the ordering transition is indeed in
the KT universality class.Comment: 4 pages, 5 figure
Stabilization of collapse and revival dynamics by a non-Markovian phonon bath
Semiconductor quantum dots (QDs) have been demonstrated to be versatile
candidates to study the fundamentals of light-matter interaction [1-3]. In
contrast with atom optics, dissipative processes are induced by the inherent
coupling to the environment and are typically perceived as a major obstacle
towards stable performances in experiments and applications [4].
In this paper we show that this is not necessarily the case. In fact, the
memory of the environment can enhance coherent quantum optical effects. In
particular, we demonstrate that the non-Markovian coupling to an incoherent
phonon bath has a stabilizing effect on the coherent QD cavity-quantum
electrodynamics (cQED) by inhibiting irregular oscillations and boosting
regular collapse and revival patterns. For low photon numbers we predict QD
dynamics that deviate dramatically from the well-known atomic Jaynes-Cummings
model. Our proposal opens the way to a systematic and deliberate design of
photon quantum effects via specifically engineered solid-state environments.Comment: 5 pages, 4 figure
Density-matrix theory of the optical dynamics and transport in quantum cascade structures: The role of coherence
The impact of coherence on the nonlinear optical response and stationary
transport is studied in quantum cascade laser structures. Nonequilibrium
effects such as pump-probe signals, the spatio-temporally resolved electron
density evolution, and the subband population dynamics (Rabi flopping) as well
as the stationary current characteristics are investigated within a microscopic
density-matrix approach. Focusing on the stationary current and the recently
observed gain oscillations, it is found that the inclusion of coherence leads
to observable coherent effects in opposite parameter regimes regarding the
relation between the level broadening and the tunnel coupling across the main
injection barrier. This shows that coherence plays a complementary role in
stationary transport and nonlinear optical dynamics in the sense that it leads
to measurable effects in opposite regimes. For this reason, a fully coherent
consideration of such nonequilibrium structures is necessary to describe the
combined optical and transport propertiesComment: 14 pages, 11 figures; final versio
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