875 research outputs found
Could a different management routine that strengthens the mother-offspring bond contribute to a more efficient organic piglet production?
In current Swedish organic piglet production full reproductive potential of the sows and growth potential of piglets are not achieved. The efficiency is held back by occurrence of lactational oestrus, low litter weight and large weight variation within litter. Therefore it is critical that these obstacles are reduced in a way that is easy to adapt in practice and does not contradict the ideas behind organic animal husbandry.
This project aims to an improvement of the conditions needed to efficiently produce organic piglets in a batch wise manner. The batch wise breeding will reduce production costs and increase disease control.
Our preliminary results indicate that the sow’s weaning to oestrus interval can be affected by the time spent in individual farrowing pen during the lactational period
Surface Integral Analogy Approaches to Computing Noise Generated by a 3D High-Lift Wing Configuration
Three surface integral approaches of the acoustic analogies are studied to predict the noise from a three-dimensional, high-lift wing configuration. The approaches refer to the
Kirchhoff method, the Ffowcs Williams and Hawkings method of the permeable integral surface and the Curle method. The first two approaches are used to compute the noise
generated by the core flow region where the energetic structures exist. The last approach is adopted to predict the noise specifically from the pressure perturbation on the wall. A new way to construct the integral surface that encloses the core region is proposed for the first two methods. Considering the local properties of the flow around the complex objective – the actual wing with high-lift devices – the integral surface based on the vorticity is constructed to follow the flow structures. The noise from the core flow region is based on the dependent integral quantities, which are indicated by the Kirchhoff formulation and by the FWH formulation. The role of each wall component on noise contribution is analyzed using the Curle method. The results of the three methods are then compared
Activation of Ca2+-Dependent K+ Channels Contributes to Rhythmic Firing of Action Potentials in Mouse Pancreatic β Cells
We have applied the perforated patch whole-cell technique to β cells within intact pancreatic islets to identify the current underlying the glucose-induced rhythmic firing of action potentials. Trains of depolarizations (to simulate glucose-induced electrical activity) resulted in the gradual (time constant: 2.3 s) development of a small (<0.8 nS) K+ conductance. The current was dependent on Ca2+ influx but unaffected by apamin and charybdotoxin, two blockers of Ca2+-activated K+ channels, and was insensitive to tolbutamide (a blocker of ATP-regulated K+ channels) but partially (>60%) blocked by high (10–20 mM) concentrations of tetraethylammonium. Upon cessation of electrical stimulation, the current deactivated exponentially with a time constant of 6.5 s. This is similar to the interval between two successive bursts of action potentials. We propose that this Ca2+-activated K+ current plays an important role in the generation of oscillatory electrical activity in the β cell
Perturbation Theory and Control in Classical or Quantum Mechanics by an Inversion Formula
We consider a perturbation of an ``integrable'' Hamiltonian and give an
expression for the canonical or unitary transformation which ``simplifies''
this perturbed system. The problem is to invert a functional defined on the
Lie- algebra of observables. We give a bound for the perturbation in order to
solve this inversion. And apply this result to a particular case of the control
theory, as a first example, and to the ``quantum adiabatic transformation'', as
another example.Comment: Version 8.0. 26 pages, Latex2e, final version published in J. Phys.
Activation of protein kinases and inhibition of protein phosphatases play a central role in the regulation of exocytosis in mouse pancreatic beta cells.
Singularities, Lax degeneracies and Maslov indices of the periodic Toda chain
The n-particle periodic Toda chain is a well known example of an integrable
but nonseparable Hamiltonian system in R^{2n}. We show that Sigma_k, the k-fold
singularities of the Toda chain, ie points where there exist k independent
linear relations amongst the gradients of the integrals of motion, coincide
with points where there are k (doubly) degenerate eigenvalues of
representatives L and Lbar of the two inequivalent classes of Lax matrices
(corresponding to degenerate periodic or antiperiodic solutions of the
associated second-order difference equation). The singularities are shown to be
nondegenerate, so that Sigma_k is a codimension-2k symplectic submanifold.
Sigma_k is shown to be of elliptic type, and the frequencies of transverse
oscillations under Hamiltonians which fix Sigma_k are computed in terms of
spectral data of the Lax matrices. If mu(C) is the (even) Maslov index of a
closed curve C in the regular component of R^{2n}, then (-1)^{\mu(C)/2} is
given by the product of the holonomies (equal to +/- 1) of the even- (or odd-)
indexed eigenvector bundles of L and Lmat.Comment: 25 pages; published versio
Results of the EUROTeV Post Collision Line Design (PCDL) Task
This paper is the deliverable of the EUROTeV Post Collision Line Design (PCDL) task and gives an overview of the published results
A multi-instrument comparison of integrated water vapour measurements at a high latitude site
We compare measurements of integrated water vapour (IWV) over a subarctic site (Kiruna, Northern Sweden) from five different sensors and retrieval methods: Radiosondes, Global Positioning System (GPS), ground-based Fourier-transform infrared (FTIR) spectrometer, groundbased microwave radiometer, and satellite-based microwave radiometer (AMSU-B). Additionally, we compare also to ERA-Interim model reanalysis data. GPS-based IWV data have the highest temporal coverage and resolution and are chosen as reference data set. All datasets agree reasonably well, but the ground-based microwave instrument only if the data are cloud-filtered. We also address two issues that are general for such intercomparison studies, the impact of different lower altitude limits for the IWV integration, and the impact of representativeness error. We develop methods for correcting for the former, and estimating the random error contribution of the latter. A literature survey reveals that reported systematic differences between different techniques are study-dependent and show no overall consistent pattern. Further improving the absolute accuracy of IWV measurements and providing climate-quality time series therefore remain challenging problems
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