Prophylactic effect of dietary zinc in a laboratory mouse model of swine dysentery

Reduced prevalence of diarrhea and mortality has been reported after dietary supplementation with zinc compounds in swine with naturally acquired colibacillosis and those challenge-exposed with Serpulina hyodysenteriae; however, the usefulness of this approach for control of enteric diseases of swine remains to be determined. To examine the effect of dietary zinc-containing compounds on the colonization and development of cecal lesions associated with S hyodysenteriae infection, a defined diet alone or with added ZnO, ZnSO4, or Zn-methionine complex to a final concentration of approximately 6,000 mg of Zn2+/kg of complete feed was fed ad libitum to 156 female mice (strain C3H/HeN) for 10 days prior to oral inoculation either with S hyodysenteriae or sterile trypticase soy broth. Rations were continued for 42 days, while at weekly intervals, 3 mice/group were necropsied for determination of body weight, cecal weight, liver zinc concentration, presence of S hyodysenteriae in the cecum, and gross and histologic assessments of cecal lesions. From postinoculation day 0 to 42, the liver zinc concentration of mice fed the zinc-supplemented diets was approximately twice that of mice fed the basal diet, irrespective of the source of zinc. From postinoculation day 7 through 42, the overall recovery rate of S hyodysenteriae in infected mice fed the basal diet was 77.8%. In contrast, recovery rates of S hyodysenteriae from S hyodysenteriae-inoculated mice fed the zinc-supplemented diets were 0% for Zn-methionine and ZnO and 16.7% for ZnSO4. Mice fed the basal diet had significantly (P < 0.05) higher weight gain than mice fed the zinc-supplemented diets.(ABSTRACT TRUNCATED AT 250 WORDS)     

A new algorithm for computing the indentation of a rigid body of arbitrary shape on a viscoelastic half-space

In this paper the contact problem between a rigid indenter of arbitrary shape and a viscoelastic half-space is considered. Under the action of a normal force the penetration of the indenter and the distribution of contact pressure change. We wish to find the relations which link the pressure distribution, the resultant force on the indenter and the penetration on the assumption that the surfaces are frictionless. For indenters of arbitrary shape the problem may be solved numerically by using the Matrix Inversion Method (MIM), extended to viscoelastic case. In this method the boundary conditions are satisfied exactly at specified “matching points” (the mid-points of the boundary elements). It can be validated by comparing the numerical results to the analytic solutions in cases of a spherical asperity (loading and unloading) and a conical asperity (loading only). Finally, the method was implemented for a finite cylindrical shape with its curved face indenting the surface of the half-space. This last example shows the efficiency of the method in case of a prescribed penetration as well as a given normal load history.     

Effect of the Superalloy Composition on the Isothermal Oxidation Behaviour of TBC Systems

The isothermal oxidation behaviour of TBC systems based on a first-generation superalloy, AM1 and a fourth-generation one, MCNG, was investigated and compared. The main difference between both is the addition of Re, Ru and Hf in the MCNG composition. The systems consisted of a Pt-modified nickel aluminide (Ni,Pt)Al bond coat deposited on the superalloy and with or without a yttria-stabilized zirconia ceramic top coat. Isothermal oxidations were performed at 1,100 °C in synthetic air for 10, 50, 500 and 1,000 h. The MCNG-based system exhibited a better spallation resistance than the AM1-based one and a lower oxidation rate. Spallation always occurred at the thermally grown oxide/bond coat interface. For both systems, transformation of the β-phase into the γ′-phase was observed. In the MCNG-based samples, the β-(Ni,Pt)Al was enriched in ruthenium and the secondary reaction zone strongly extends, whereas chromium precipitation occurred in the AM1-based ones.     

Efficient frameworks for greedy split and new depth first search split procedures for routing problems

Split procedures have proven their efficiency within global optimization frameworks for routing problems by splitting giant tours into trips. This is done by generating an optimal shortest path within an auxiliary graph constructed from the giant tour. This article provides a state of the art of split practice in routing problems and gives its key features. The efficiency of the method critically depends on the node-splitting procedure and on the upper and lower bound approximations. Suitable complexity can be obtained using a new depth first search procedure which is introduced here and provides a new algorithm that is specially designed for large scale problems with resource constraints. Experiments show that the depth first search split procedure introduced in this article, used as an evaluation function in a global framework, can improve the results obtained by the use of the “classical” split procedure on the Location-Routing Problem and the Heterogeneous Vehicle Routing Problem. The Location-Routing Problem is also used to provide further analysis and a fair comparative study between the two split versions.     

A discrete element study of settlement in vibrated granular layers: role of contact loss and acceleration

This paper deals with the vibration of granular materials due to cyclic external excitation. It highlights the effect of the acceleration on the settlement speed and proves the existence of a relationship between settlement and loss of contacts in partially confined granular materials under vibration. The numerical simulations are carried out using the Molecular Dynamics method, where the discrete elements consist of polygonal grains. The data analyses are conducted based on multivariate autoregressive models to describe the settlement and permanent contacts number with respect to the number of loading cycles.     

Specificity of practice: Interaction between concurrent sensory information and terminal feedback.

In 2 experiments, the authors investigated a potential interaction involving the processing of concurrent feedback using design features from the specificity of practice literature and the processing of terminal feedback using a manipulation from the guidance hypothesis literature. In Experiment 1, participants produced (198 trials) flexion-extension movements to reproduce a specific pattern of displacement over time with or without vision of the limb position and with 100% or 33% knowledge of results (KR) frequency. The transfer test was performed without vision and KR. In Experiment 2, the authors assessed whether sensory information processing was modulated by the amount of practice. Participants performed 54 or 396 trials under a 100% or a 33% KR frequency with vision before being transferred to a no-vision condition without KR. Results of both experiments indicated that the Vision-33% condition suffered a larger detrimental effect of withdrawing visual information than the Vision-100% condition. Experiment 2 indicated that this detrimental effect increased with practice. These results indicated the reduction in terminal feedback prompted participants to more deeply process the concurrent visual information thus reinforcing their dependency on the visual information. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Robust source decoding of variable-length encoded video data taking into account source constraints

We first provide an analysis of available redundancy remaining in compressed video data. This residual redundancy has two origins: the variable-length code (VLC) syntax and the source constraints. We compute the two in terms of equivalent redundancy bits. Then, a VLC decoding algorithm able to exploit both VLC syntax and source constraints for improving the decoding performance is outlined. Finally, it is shown that by taking this redundancy into account, video decoding over additive white Gaussian noise channels is substantially improved.