309 research outputs found
Effect of organic pig production systems on performance and meat quality
The present study was carried out to establish knowledge of consequence for setting up guidelines of importance for production of competitive organic pork of high quality. Performance and meat quality characteristics were compared between three organic pig production systems based on indoor housing with access to an outdoor area and a Danish conventional indoor system including 100% concentrate during the finishing feeding stage.
The three organic systems used the following three feeding regimes: 100% organic concentrate according to Danish recommendations, 70% organic concentrate (restricted) plus ad libitum organic barley/pea silage and 70% organic concentrate (restricted) plus ad libitum organic clover grass silage, respectively. With exception of a slightly lower daily gain in organic pigs fed 100% concentrate, no significant difference was found in performance and meat quality characteristics compared with results obtained in the conventional system. In contrast and independent of roughage used, organic pigs raised on 70% concentrate had a significant reduction in daily gain (P < 0.001) compared with pigs raised on 100% concentrate, despite the fact that no difference in feed conversion rate was seen between the tested production systems. However, the percentage of leanness increased significantly in meat from organic pigs raised on 70% concentrate plus roughage compared with meat from pigs given 100% concentrate. This was reflected in higher yield (weight) of lean cuts and lower yield of cuts with high fat content from pigs fed 70% concentrate plus roughage. In general, organic feeding resulted in a significantly higher content of polyunsaturated fatty acids in the back fat (1.8%), which increased further when restricted feeding plus roughage (4%) was used. Restricted concentrate feeding gave rise to a decrease in tenderness compared with pork from pigs fed 100% concentrate
Electronic structure, electron-phonon coupling and superconductivity of isotypic noncentrosymmetric crystals LiPdB and LiPtB
Electronic structure of recently discovered isotypic ternary borides
LiPdB and LiPtB, with noncentrosymmetric crystal structures, is
studied with a view to understanding their superconducting properties.
Estimates of the Fermi-surface averaged electron-phonon matrix element and
Hopfield parameter are obtained in the rigid ion approximation of Gaspari and
Gyorffy [Phys. Rev. Lett. {\bf 28} (1972) 801]. The contribution of the lithium
atoms to the electron-phonon coupling is found to be negligible, while both
boron and palladium atoms contribute equally strongly to the Hopfield
parameter. There is a significant transfer of charge from lithium, almost the
entire valence charge, to the B-Pd(Pt) complex. The electronic structure and
superconducting properties of LiPdB, thus, can be understood from the
viewpoint of the compound being composed of a connected array of B-Pd
tetrahedra decoupled from the backbone of Li atoms, which are connected by
relatively short bonds. Our results suggest that conventional s-wave
electron-phonon interaction without explicit consideration of SO coupling can
explain qualitatively the observed in LiPdB. However, such an
approach is likely to fail to describe superconductivity in LiPtB.Comment: 14 pages, 4 figures An erroneous statement following Eq. 6 in version
1 has been deleted. A statement regarding the possible inadequacy of Eq. 6
has been added following Eq. 6. At two places in the discussion Refs. 37,39
has been changed to 37-39, as it should b
Phasic alertness and multisensory integration contribute to visual awareness of weak visual targets in audio-visual stimulation under Continuous Flash Suppression
This work was supported by the Biotechnology and Biological Sciences Research Council(BBSRC) [grant number BB/M010996/1].Peer reviewedPublisher PD
Enhanced orbital electron-capture nuclear decay rate in compact medium
The eigenstate energies of an atom increase under spatial confinement and
this effect should also increase the electron density of the orbital electrons
at the nucleus thus increasing the decay rate of an electron-capturing
radioactive nucleus. We have observed that the orbital electron capture rates
of 109In and 110Sn increased by (1.00+-0.17)% and (0.48+-0.25)% respectively
when implanted in the small Au lattice versus large Pb lattice. These results
have been understood because of the higher compression experienced by the large
radioactive atoms due to the spatial confinement in the smaller Au lattice.Comment: 30 pages, 3 Figures, 2 Table
A batch-service queueing model with a discrete batch Markovian arrival process
Queueing systems with batch service have been investigated extensively during the past decades. However, nearly all the studied models share the common feature that an uncorrelated arrival process is considered, which is unrealistic in several real-life situations. In this paper, we study a discrete-time queueing model, with a server that only initiates service when the amount of customers in system (system content) reaches or exceeds a threshold. Correlation is taken into account by assuming a discrete batch Markovian arrival process (D-BMAP), i.e. the distribution of the number of customer arrivals per slot depends on a background state which is determined by a first-order Markov chain. We deduce the probability generating function of the system content at random slot marks and we examine the influence of correlation in the arrival process on the behavior of the system. We show that correlation merely has a small impact on the threshold that minimizes the mean system content. In addition, we demonstrate that correlation might have a significant influence on the system content and therefore has to be included in the model
Onset of magnetism in B2 transition metals aluminides
Ab initio calculation results for the electronic structure of disordered bcc
Fe(x)Al(1-x) (0.4<x<0.75), Co(x)Al(1-x) and Ni(x)Al(1-x) (x=0.4; 0.5; 0.6)
alloys near the 1:1 stoichiometry, as well as of the ordered B2 (FeAl, CoAl,
NiAl) phases with point defects are presented. The calculations were performed
using the coherent potential approximation within the Korringa-Kohn-Rostoker
method (KKR-CPA) for the disordered case and the tight-binding linear
muffin-tin orbital (TB-LMTO) method for the intermetallic compounds. We studied
in particular the onset of magnetism in Fe-Al and Co-Al systems as a function
of the defect structure. We found the appearance of large local magnetic
moments associated with the transition metal (TM) antisite defect in FeAl and
CoAl compounds, in agreement with the experimental findings. Moreover, we found
that any vacancies on both sublattices enhance the magnetic moments via
reducing the charge transfer to a TM atom. Disordered Fe-Al alloys are
ferromagnetically ordered for the whole range of composition studied, whereas
Co-Al becomes magnetic only for Co concentration >0.5.Comment: 11 pages with 9 embedded postscript figures, to be published in
Phys.Rev.
X-ray standing wave and reflectometric characterization of multilayer structures
Microstructural characterization of synthetic periodic multilayers by x-ray
standing waves have been presented. It has been shown that the analysis of
multilayers by combined x-ray reflectometry (XRR) and x-ray standing wave (XSW)
techniques can overcome the deficiencies of the individual techniques in
microstructural analysis. While interface roughnesses are more accurately
determined by the XRR technique, layer composition is more accurately
determined by the XSW technique where an element is directly identified by its
characteristic emission. These aspects have been explained with an example of a
20 period Pt/C multilayer. The composition of the C-layers due to Pt
dissolution in the C-layers, PtC, has been determined by the XSW
technique. In the XSW analysis when the whole amount of Pt present in the
C-layers is assumed to be within the broadened interface, it l eads to larger
interface roughness values, inconsistent with those determined by the XRR
technique. Constraining the interface roughness values to those determined by
the XRR technique, requires an additional amount of dissolved Pt in the
C-layers to expl ain the Pt fluorescence yield excited by the standing wave
field. This analysis provides the average composition PtC of the
C-layers .Comment: 12 pages RevTex, 10 eps figures embedde
Transport spin polarization of Ni_xFe_{1-x}: electronic kinematics and band structure
We present measurements of the transport spin polarization of Ni_xFe_{1-x}
(0<x<1) using the recently-developed Point Contact Andreev Reflection
technique, and compare them with our first principles calculations of the spin
polarization for this system. Surpisingly, the measured spin polarization is
almost composition-independent. The results clearly demonstrate that the sign
of the transport spin polarization does not coincide with that of the
difference of the densities of states at the Fermi level. Calculations indicate
that the independence of the spin polarization of the composition is due to
compensation of density of states and Fermi velocity in the s- and d- bands
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