542 research outputs found
Effects of a ruminally protected B vitamin supplement on milk yield and composition of lactating dairy cows
It is not clear if B vitamins supplied to the small intestine of dairy cows from dietary and rumen
microbial sources are provided in sufficient quantity to maximize animal performance. Our objective
was to determine effects of adding a ruminally protected B vitamin blend supplement, containing
biotin, folic acid, pantothenic acid and pyridoxine, to the diet of high producing dairy cows on their
productivity. Two dairy facilities located in California (USA) were used, one with mid lactation
Holstein cows (Experiment 1) and the other with early lactation Holstein cows (Experiment 2). In
each Experiment, cows were randomly assigned to treatment in a 2Ă—2 crossover design with 28 d
(Experiment 1) or 35 d (Experiment 2) experimental periods. In Experiment 1, milk and milk fat
yield were unaffected by treatment, although milk fat proportion was lower (37.1 versus 36.3 g/kg;
P<0.01), but milk protein yield was higher (1.21 versus 1.24 kg/d; P=0.02) in cows fed B vitamins.
In Experiment 2, milk (39.60 versus 40.46 kg/d; P=0.02), milk fat (1.40 versus 1.47 kg/d; P<0.01)
and milk protein yield (1.10 versus 1.16 kg/d; P<0.01), as well as milk energy output (113.2 versus
117.8 MJ/d; P<0.01) were all higher with B vitamin feeding. Body condition score (BCS) increasedmore with B vitamin feeding in Experiment 2, but was unaffected in Experiment 1. Body locomotion
score (BLS) increased with B vitamin feeding in both experiments (P=0.01 and < 0.01, respectively),
possibly an indication of reduced locomotory ability.Overall, productivity of high producing lactating
dairy cows responded positively to feeding a mixture of ruminally protected B vitamins, although
differences in the extent of the positive responses between experiments perhaps suggests that early
lactation cows, with lower DM intake to milk yield ratios, may be more responsive to ruminally
protected B vitamins than mid lactation cows, with higher DM intake to milk yield ratios
The Effectiveness of Intrathecal Baclofen in the Management of Patients with Severe Spasticity
Transient behavior in Single-File Systems
We have used Monte-Carlo methods and analytical techniques to investigate the
influence of the characteristics, such as pipe length, diffusion, adsorption,
desorption and reaction rates on the transient properties of Single-File
Systems. The transient or the relaxation regime is the period in which the
system is evolving to equilibrium. We have studied the system when all the
sites are reactive and when only some of them are reactive. Comparisons between
Mean-Field predictions, Cluster Approximation predictions, and Monte Carlo
simulations for the relaxation time of the system are shown. We outline the
cases where Mean-Field analysis gives good results compared to Dynamic
Monte-Carlo results. For some specific cases we can analytically derive the
relaxation time. Occupancy profiles for different distribution of the sites
both for Mean-Field and simulations are compared. Different results for slow
and fast reaction systems and different distribution of reactive sites are
discussed.Comment: 18 pages, 19 figure
The Dimensional-Reduction Anomaly in Spherically Symmetric Spacetimes
In D-dimensional spacetimes which can be foliated by n-dimensional
homogeneous subspaces, a quantum field can be decomposed in terms of modes on
the subspaces, reducing the system to a collection of (D-n)-dimensional fields.
This allows one to write bare D-dimensional field quantities like the Green
function and the effective action as sums of their (D-n)-dimensional
counterparts in the dimensionally reduced theory. It has been shown, however,
that renormalization breaks this relationship between the original and
dimensionally reduced theories, an effect called the dimensional-reduction
anomaly. We examine the dimensional-reduction anomaly for the important case of
spherically symmetric spaces.Comment: LaTeX, 19 pages, 2 figures. v2: calculations simplified, references
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Landau-De Gennes theory of nematic liquid\ud crystals: the Oseen-Frank limit and beyond
We study global minimizers of a continuum Landau-De Gennes energy functional for nematic liquid crystals, in three-dimensional domains, subject to uniaxial boundary conditions. We analyze the physically relevant limit of small elastic constant and show that global minimizers converge strongly, in W 1,2 , to a global minimizer predicted by the Oseen-Frank theory for uniaxial nematic liquid crystals with constant order parameter. Moreover, the convergence is uniform in the interior of the domain, away from the singularities of the limiting Oseen-Frank global minimizer. We obtain results on the rate of convergence of the eigenvalues and the regularity of the eigenvectors of the Landau-De Gennes global minimizer.\ud
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We also study the interplay between biaxiality and uniaxiality in Landau-De Gennes global energy minimizers and obtain estimates for various related quantities such as the biaxiality parameter and the size of admissible strongly biaxial regions
Dilute magnetic contact for a spin GaN HEMT
Semiconductor CMOS nano-electronics is intensively seeking solutions for future digital applications. One of the most promising solutions to deliver a technological breakthrough is exploring electron spin in metals and semiconductors with applications from spin transistors to quantum sensors, and quantum computing. Spintronic applications rely on magnetic semiconductor materials with suitable properties. In particular, dilute magnetic semiconductors (DMS), such as Mn doped GaN, show the great promise of a high Curie temperature (220K–370K), exceeding room temperature, and a large concentration of holes. These are all the essential pre-requisites for operation of spin transistors in circuits. In this work, we dope an AlGaN/GaN heterostructure consisting of a GaN (2 nm) cap layer, an Al0.25Ga0.75N (25 nm) barrier, and a GaN (2 μm) substrate grown on a 6” Si wafer with Mn by sputtering deposition and thermal annealing to create a dilute magnetic semiconductor material following the process flow. While initial attempts resulted in the formation of a MnO surface layer, the SEM/XDS and XPS data suggest a diffusion of Mn into the GaN layer using thermal annealing at 900◦C for 7h with a concentration of 4.5% which is very close to the desired concentration of 5% needed for a DMS. The annealing temperature has to be below 1000◦ C since temperatures around 1000◦C result in significant damage to the 2DEG and diffusion of Al from the AlGaN layer
Heat release by controlled continuous-time Markov jump processes
We derive the equations governing the protocols minimizing the heat released
by a continuous-time Markov jump process on a one-dimensional countable state
space during a transition between assigned initial and final probability
distributions in a finite time horizon. In particular, we identify the
hypotheses on the transition rates under which the optimal control strategy and
the probability distribution of the Markov jump problem obey a system of
differential equations of Hamilton-Bellman-Jacobi-type. As the state-space mesh
tends to zero, these equations converge to those satisfied by the diffusion
process minimizing the heat released in the Langevin formulation of the same
problem. We also show that in full analogy with the continuum case, heat
minimization is equivalent to entropy production minimization. Thus, our
results may be interpreted as a refined version of the second law of
thermodynamics.Comment: final version, section 2.1 revised, 26 pages, 3 figure
Multi-level Dynamical Systems: Connecting the Ruelle Response Theory and the Mori-Zwanzig Approach
In this paper we consider the problem of deriving approximate autonomous
dynamics for a number of variables of a dynamical system, which are weakly
coupled to the remaining variables. In a previous paper we have used the Ruelle
response theory on such a weakly coupled system to construct a surrogate
dynamics, such that the expectation value of any observable agrees, up to
second order in the coupling strength, to its expectation evaluated on the full
dynamics. We show here that such surrogate dynamics agree up to second order to
an expansion of the Mori-Zwanzig projected dynamics. This implies that the
parametrizations of unresolved processes suited for prediction and for the
representation of long term statistical properties are closely related, if one
takes into account, in addition to the widely adopted stochastic forcing, the
often neglected memory effects.Comment: 14 pages, 1 figur
Determinant representation for some transition probabilities in the TASEP with second class particles
We study the transition probabilities for the totally asymmetric simple
exclusion process (TASEP) on the infinite integer lattice with a finite, but
arbitrary number of first and second class particles. Using the Bethe ansatz we
present an explicit expression of these quantities in terms of the Bethe wave
function. In a next step it is proved rigorously that this expression can be
written in a compact determinantal form for the case where the order of the
first and second class particles does not change in time. An independent
geometrical approach provides insight into these results and enables us to
generalize the determinantal solution to the multi-class TASEP.Comment: Minor revision; journal reference adde
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