Importance of standardizing raw milk quality for the enhancement of Croatian market competitiveness

In the European Union member states (EU), it is necessary to evaluate hygienic condition of milk in order to determine milk price. Similar requirement was set by the Republic of Croatia in 2000. The Rulebook defines minimal quality criteria that fresh raw milk must have in order to be purchased. Upon completion of analysis, milk is classified into quality classes, each having a defined price. Increased value of somatic cell count (SCC) (higher than 400.000/ml) and MO (higher than 100.000/ml) directly decreases the raw milk price, while higher content of fat and protein causes its increase. Since the system of market milk price formation was established, producers have been stimulated to produce milk of higher quality: in a total of milk being purchased, the highest quality milk share increased from 23.3% to 34.2%. Referring to a trend of milk purchase price reduction in the EU, and considering the current high milk purchase price in Croatia, Croatian producers have an opportunity to improve conditions in milk industry before the country joins the EU. Current milk production needs to be increased and milk quality also needs to be improved, in order to make Croatian milk production more competitive on the European, as well as world market.milk quality, competitiveness, market, Croatia, Food Consumption/Nutrition/Food Safety, Livestock Production/Industries, Marketing,

Influence of Microclimate in a Barn on Dairy Cows’ Welfare and Production

Microclimate in a barn has a major influence on cows’ health and welfare, as well as on milk production of dairy cows. Extreme values of air temperature and humidity can negatively influence barn conditions, having thus negative effect on cows kept in barns. The research aimed to investigate influence of basic microclimate parameters on a modern dairy farm located in Eastern Croatia. Research period referred to summer season, from 01 June – 31 August 2013. Measurements were carried out in three time intervals (00:00-08:00; 08:00-16:00; 16:00-00:00) for the following parameters: temperature (T), humidity (H) and temperature-humidity index (THI). The results showed that the values of T and THI were higher than optimal values recommended by the scientific literature. Differences between the daily interval for T, H and THI were statistically highly significant (p<0.0001). Furthermore, significant difference (p<0.0001; p<0.05) was determined for all investigated parameters between June and July, and June and August. However, between July and August there was no significant difference. Although measurements were performed on a modern dairy farm equipped with additional cooling by fans, it was not sufficient to create an optimal microclimate environment for dairy cows. Because of that, additional measures need to be undertaken during summer months (for example, installation of water sprinklers) to reduce the air temperature and temperature-humidity index, all with the purpose to increase comfort of dairy cows and to prevent decrease in milk production

Extended Gravity Theories and the Einstein-Hilbert Action

I discuss the relation between arbitrarily high-order theories of gravity and scalar-tensor gravity at the level of the field equations and the action. I show that $(2n+4)$-order gravity is dynamically equivalent to Brans-Dicke gravity with an interaction potential for the Brans-Dicke field and $n$ further scalar fields. This scalar-tensor action is then conformally equivalent to the Einstein-Hilbert action with $n+1$ scalar fields. This clarifies the nature and extent of the conformal equivalence between extended gravity theories and general relativity with many scalar fields.Comment: 12 pages, Plain Latex, SUSSEX-AST-93/7-

Stochastic emergence of inflaton fluctuations in a SdS primordial universe with large-scale repulsive gravity from a 5D vacuum

We develop a stochastic approach to study scalar field fluctuations of the inflaton field in an early inflationary universe with a black-hole (BH), which is described by an effective 4D SdS metric. Considering a 5D Ricci-flat SdS static metric, we implement a planar coordinate transformation, in order to obtain a 5D cosmological metric, from which the effective 4D SdS metric can be induced on a 4D hypersurface. We found that at the end of inflation, the squared fluctuations of the inflaton field are not exactly scale independent and becomes sensitive with the mass of the BH.Comment: version accepted in European Physical Journal Plu

Accelerated Cosmological Models in Ricci squared Gravity

Alternative gravitational theories described by Lagrangians depending on general functions of the Ricci scalar have been proven to give coherent theoretical models to describe the experimental evidence of the acceleration of universe at present time. In this paper we proceed further in this analysis of cosmological applications of alternative gravitational theories depending on (other) curvature invariants. We introduce Ricci squared Lagrangians in minimal interaction with matter (perfect fluid); we find modified Einstein equations and consequently modified Friedmann equations in the Palatini formalism. It is striking that both Ricci scalar and Ricci squared theories are described in the same mathematical framework and both the generalized Einstein equations and generalized Friedmann equations have the same structure. In the framework of the cosmological principle, without the introduction of exotic forms of dark energy, we thus obtain modified equations providing values of w_{eff}<-1 in accordance with the experimental data. The spacetime bi-metric structure plays a fundamental role in the physical interpretation of results and gives them a clear and very rich geometrical interpretation.Comment: New version: 26 pages, 1 figure (now included), Revtex

Classical and Quantum Solutions and the Problem of Time in R2R^2 Cosmology

We have studied various classical solutions in $R^2$ cosmology. Especially we have obtained general classical solutions in pure $R^2$\ cosmology. Even in the quantum theory, we can solve the Wheeler-DeWitt equation in pure $R^2$\ cosmology exactly. Comparing these classical and quantum solutions in $R^2$\ cosmology, we have studied the problem of time in general relativity.Comment: 17 pages, latex, no figure, one reference is correcte

Quantum Cosmology and Higher-Order Lagrangian Theories

In this paper the quantum cosmological consequences of introducing a term cubic in the Ricci curvature scalar $R$ into the Einstein--Hilbert action are investigated. It is argued that this term represents a more generic perturbation to the action than the quadratic correction usually considered. A qualitative argument suggests that there exists a region of parameter space in which neither the tunneling nor the no-boundary boundary conditions predict an epoch of inflation that can solve the horizon and flatness problems of the big bang model. This is in contrast to the $R^2$--theory.Comment: 13 pages, LaTeX, preprint FERMILAB-Pub-94/XXX-A, March 199

Spontaneous decompactification

Positive vacuum energy together with extra dimensions of space imply that our four-dimensional Universe is unstable, generically to decompactification of the extra dimensions. Either quantum tunneling or thermal fluctuations carry one past a barrier into the decompactifying regime. We give an overview of this process, and examine the subsequent expansion into the higher- dimensional geometry. This is governed by certain fixed-point solutions of the evolution equations, which are studied for both positive and negative spatial curvature. In the case where there is a higher-dimensional cosmological constant, we also outline a possible mechanism for compactification to a four-dimensional de Sitter cosmology.Comment: 27 pages, 5 figures, harvmac. v2: refs added, minor notation change

R+R2R + R^2 Gravity as R+R + Backreaction

Quadratic theory of gravity is a complicated constraint system. We investigate some consequences of treating quadratic terms perturbatively (higher derivative version of backreaction effects). This approach is shown to overcome some well known problems associated with higher derivative theories, i.e., the physical gravitational degree of freedom remains unchanged from those of Einstein gravity. Using such an interpretation of $R + \beta R^2$ gravity, we investigate a classical and Wheeler DeWitt evolution of $R + \beta R^2$ gravity for a particular sign of $\beta$, corresponding to non- tachyon case. Matter is described by a phenomenological $\rho \propto a(t)^{-n}$. It is concluded that both the Friedmann potential $U(a)$ (${\dot a}^2 + 2U(a) = 0$) and the Wheeler DeWitt potential $W(a)$ ($\left[-{\partial^2\over \partial a^2} + 2W(a)\right]\psi (a) =0$) develop repulsive barriers near $a\approx 0$ for $n>4$ (i.e., $p > {1\over 3}\rho$). The interpretations is clear. Repulsive barrier in $U(a)$ implies that a contracting FRW universe ($k>0, k=0, k<0$) will bounce to an expansion phase without a total gravitational collapse. Repulsive barrier in $W(a)$ means that $a \approx 0$ is a classically forbidden region. Therefore, probability of finding a universe with the big bang singularity ($a=0$ ) is exponentially suppressed.Comment: Accepted for publication in Phy. Rev. D.,18 pages, 6 figures, Latex fil

Stochastic evolution of cosmological parameters in the early universe

We develop a stochastic formulation of cosmology in the early universe, after considering the scatter in the redshift-apparent magnitude diagram in the early epochs as an observational evidence for the non-deterministic evolution of early universe. We consider the stochastic evolution of density parameter in the early universe after the inflationary phase qualitatively, under the assumption of fluctuating $w$ factor in the equation of state, in the Fokker-Planck formalism. Since the scale factor for the universe depends on the energy density, from the coupled Friedmann equations we calculated the two variable probability distribution function assuming a flat space geometry.Comment: 10 page