ENERGY LEVEL AND STRATEGY OF FEEDING FOR DAIRY COWS IN THE DRY PERIOD

Djelovanje strategije hranidbe u suhostaju na proizvodnju i zdravlje istaživalo se u dva pokusa što su obuhvatila 80 i 96 mliječnih krava. U pokusu br. 1 ispitivalo se djelovanje razine energije (normalna i visoka (1.5 x N) i djelovanje dnevnog sagorjevanja kratkolančanih masnih kiselina (KLMK) u preživača (+ i -) u zadnja četiri tjedna suhostaja. U pokusu br. 2 uključeno je samo sagorjevanje KLMK. Šesnaest je krava zaklano radi ruminalnog pregleda. Sagorjevanje KLMK je inducirano davanjem 4.5 kg ječma u jutro i kabaste hrane (roughage) na večer. Nakon telenja koncentracija je postepeno povećavana do razine od 9 kg ST a sliaža trave bila ad lib. u obje skupine. Sagorjevanje KLMK povećalo je uzimanje silaže trave u prvih pet tjedana post parfum u pokusu br. 1, ali ne u pokusu br. 2. U pokusu br. 1 postojalo je međusobno djelovanje između razine hranjena i sagorjevanja KLMK na proizvodnju mlijeka, dok u pokusu br. 2 nije primijenjena nikakva razlika. U krava s pojačanim sagorjevanjem KLMK došlo je do rjeđe pojave ketoze i probavnih smetnji u prvom pokusu ali ne u drugom, te je postojala tendencija povećanja aktivnosti u mukozi rumena, no bez makroskopskih razlika. Zaključeno je da se sagorjevanjem KLMK ne postiže nikakvo ili samo neznatno pozitivno djelovanje u suhostaju na uzimanje hrane, proizvodnju, zdravlje i reprodukciju.The effect of feeding strategy in the dry period on performance and health was investigated in two experiments comprising 80 and 96 dairy cows. In exp. 1 the effect of energy level (Normal and High (1.5 x N) and the effect of a daily ruminal SCFA-burst (+ and -) in the last 4 weeks of the dry period were examined. In exp. 2. only SCFA-burst was included. Sixteen cows were slaughtered for ruminal examination. SCFA-burst was induced by allocating 4.5 kg barley in the morning and roughage in the evening. After calving concentrate was gradually increased to a level of 9 kg DM and grass silage was ad. lib in all groups. The SCFA-burst increased grass silage intake in the first 5 weeks post partum in exp. 1 but not in exp. 2. In exp. I there was an interaction between feeding level and SCFA-burst on milk production, while no difference between treatments were seen in exp. 2. The SCFA bursted cows had a lover incidence of ketose and digestive disorders in the first experiment but not in the second, and there was a tendency to increased activity in the ruminal mucosa but without any macroscopical differences. It is concluded that none or only small benefits are obtained from SCFA- bursts in the dry period on feed intake, performance, health, and reproduction

Ab initio investigation of VOSeO3, a spin gap system with coupled spin dimers

Motivated by an early experimental study of VOSeO3, which suggested that it is a quasi-2D system of weakly coupled spin dimers with a small spin gap, we have investigated the electronic structure of this material via density-functional calculations. These ab initio results indicate that the system is better thought of as an alternating spin-1/2 chain with moderate interchain interactions, an analog of (VO)2P2O7. The potential interest of this system for studies in high magnetic field given the presumably small value of the spin gap is emphasized.Comment: 4 pages, 5 figure

Violation of the Wiedemann-Franz Law in a Large-N Solution of the t-J Model

We show that the Wiedemann-Franz law, which holds for Landau Fermi liquids, breaks down in a large-n treatment of the t-J model. The calculated ratio of the in-plane thermal and electrical conductivities agrees quantitatively with experiments on the normal state of the electron-doped Pr_{2-x}Ce_xCuO_4 (x = 0.15) cuprate superconductor. The violation of the Wiedemann-Franz law in the uniform phase contrasts with other properties of the phase that are Fermi liquid like.Comment: 4 pages, 2 figures. Typos corrected, one added reference, revised discussion of experiment on 214 cuprate material (x = 0.06

Modeling of complex oxide materials from the first principles: systematic applications to vanadates RVO3 with distorted perovskite structure

"Realistic modeling" is a new direction of electronic structure calculations, where the main emphasis is made on the construction of some effective low-energy model entirely within a first-principle framework. Ideally, it is a model in form, but with all the parameters derived rigorously, on the basis of first-principles electronic structure calculations. The method is especially suit for transition-metal oxides and other strongly correlated systems, whose electronic and magnetic properties are predetermined by the behavior of some limited number of states located near the Fermi level. After reviewing general ideas of realistic modeling, we will illustrate abilities of this approach on the wide series of vanadates RVO3 (R= La, Ce, Pr, Nd, Sm, Gd, Tb, Yb, and Y) with distorted perovskite structure. Particular attention will be paid to computational tools, which can be used for microscopic analysis of different spin and orbital states in the partially filled t2g-band. We will explicitly show how the lifting of the orbital degeneracy by the monoclinic distortion stabilizes C-type antiferromagnetic (AFM) state, which can be further transformed to the G-type AFM state by changing the crystal distortion from monoclinic to orthorhombic one. Two microscopic mechanisms of such a stabilization, associated with the one-electron crystal field and electron correlation interactions, are discussed. The flexibility of the orbital degrees of freedom is analyzed in terms of the magnetic-state dependence of interatomic magnetic interactions.Comment: 23 pages, 13 figure

The nil Hecke ring and singularity of Schubert varieties

We give a criterion for smoothness of a point in any Schubert variety in any G/B in terms of the nil Hecke ring.Comment: AMSTE

Halogen-mediated exchange in the coupled-tetrahedra quantum spin systems Cu2Te2O5X2 (X=Br,Cl)

Motivated by recent discussion on possible quantum critical behavior in the coupled Cu-tetrahedra system Cu2Te2O5Br2, we present a comparative ab initio study of the electronic properties of Cu2Te2O5Br2 and the isostructural Cu2Te2O5Cl2. A detailed investigation of the copper-copper interaction pathes reveals that the halogen-ions play an important role in the inter-tetrahedral couplings via X_4-rings (X=Br, Cl). We find that, contrary to initial indications, both systems show a similar electronic behavior with long range exchange pathes mediated by the X_4-rings.Comment: 5 pages, 7 figure

Strangeness Enhancement in p+Ap+A and S+AS+A Interactions at SPS Energies

The systematics of strangeness enhancement is calculated using the HIJING and VENUS models and compared to recent data on $\,pp\,$, $\,pA\,$ and $\,AA\,$ collisions at CERN/SPS energies ($200A\,\, GeV\,$). The HIJING model is used to perform a {\em linear} extrapolation from $pp$ to $AA$. VENUS is used to estimate the effects of final state cascading and possible non-conventional production mechanisms. This comparison shows that the large enhancement of strangeness observed in $S+Au$ collisions, interpreted previously as possible evidence for quark-gluon plasma formation, has its origins in non-equilibrium dynamics of few nucleon systems. % Strangeness enhancement %is therefore traced back to the change in the production dynamics %from $pp$ to minimum bias $pS$ and central $SS$ collisions. A factor of two enhancement of $\Lambda^{0}$ at mid-rapidity is indicated by recent $pS$ data, where on the average {\em one} projectile nucleon interacts with only {\em two} target nucleons. There appears to be another factor of two enhancement in the light ion reaction $SS$ relative to $pS$, when on the average only two projectile nucleons interact with two target ones.Comment: 29 pages, 8 figures in uuencoded postscript fil