Dietary ascorbic acid and immune response in dairy calves

Colostrum-fed, colostrum-deprived, and colostrum-fed and colostrum-deprived calves fed ascorbic acid (1.75 g/d) in whole, raw milk to 6 wk of age were sampled from 0 to 8 wk of age in order to determine whether ascorbate supplementation would increase plasma Ig concentrations, antibody response to immunization, and disease resistance. Plasma IgG concentrations were lower at 14 and 28 d of age in calves fed ascorbate compared with plasma concentrations in calves not receiving ascorbate supplementation, irrespective of colostrum feeding. Colostrum feeding had no effect on antibody titer to keyhole limpet hemocyanin at any age, but ascorbate-supplemented calves had lower plasma antibody titers to keyhole limpet hemocyanin at 35 and 56 d of age. Calves fed ascorbate had lower clinical scores for diarrhea. Dietary ascorbate does not appear to be immunostimulatory in dairy calves to 56 d of age and appeared to inhibit antibody synthesis. However, at 14 d of age there was an interaction of ascorbate supplementation and colostrum feeding; plasma IgG concentrations were higher in colostrum-deprived calves fed ascorbate then in colostrum-deprived calves not fed ascorbate.     

An axiomatic comparison of learned term-weighting schemes in information retrieval: clarifications and extensions

Machine learning approaches to information retrieval are becoming increasingly widespread. In this paper, we present term-weighting functions reported in the literature that were developed by four separate approaches using genetic programming. Recently, a number of axioms (constraints), from which all good term-weighting schemes should be deduced, have been developed and shown to be theoretically and empirically sound. We introduce a new axiom and empirically validate it by modifying the standard BM25 scheme. Furthermore, we analyse the BM25 scheme and the four learned schemes presented to determine if the schemes are consistent with the axioms. We find that one learned term-weighting approach is consistent with more axioms than any of the other schemes. An empirical evaluation of the schemes on various test collections and query lengths shows that the scheme that is consistent with more of the axioms outperforms the other schemes.     

Sexuality and quality of life among young people

Associations between quality of life and attitudes toward, and experience of, sexual activities during adolescence were investigated in a sample of 240 Australian university students. Sexuality was explored using the Sexual Knowledge, Experience and Needs Scale (SexKen). Both objective and subjective quality of life were evaluated in seven domains using the Comprehensive Quality of Life Scale (ComQol). The findings demonstrated the importance of relationships and sexual experience to satisfaction with life. The results are discussed in terms of the significance of sexuality for general well-being during adolescence.     

Pulsed laser damage thresholds in vitro for intraocular lenses and membranes

Energy and power density damage thresholds were determined in air, for plastic IOL's and membranes at the focal point of several solid-state laser systems: 1) 694 nm,Q-switched single pulse (30 ns), multimode, 2) 1064 nm,Q-switched single pulse (20 ns), TEM00, 3) 1060 nm, mode-locked single pulse, 15 ps, TEM11, 4) 530 nm, mode-locked single pulse, 15 ps, TEM11, and 5) 1064 nm, mode-locked pulse train (9-11 pulses, 30 ps), TEM00. Pulse energies bracketing damage thresholds as well as focal diameter and pulse duration for each system were determined. Energy density thresholds are lower, and power density thresholds higher, for shorter duration pulses-e.g., 23 J/cm²(1.15 GW/cm²) versus 6 J/cm²(400 GW/cm²) at the same wavelength as in systems 2) and 3) (p = 0.005). Damage thresholds for glass IOL's are 37 J/cm²(1.9 GW/cm²) and 37 J/cm²(1235 GW/cm²) as in systems 2) and 5). Damage threshold values for plastic membranes (Saran Wrap^®) exposed to nanosecond and picosecond pulse trains of Nd:YAG at 1064 nm are about half that of plastic IOL's. When laser pulses with a cone angle of 14° from systems 2) and 5) are focused on plastic membrane next to the IOL, damage thresholds are 30 J/cm²(1.5 GW/cm²) for 20 nsQ-switched pulses and 20 J/cm²(670 GW/cm²) for trains of 30 ps mode-locked pulses. Damage thresholds of IOL's immersed in 0.9 percent saline are approximately the same as those obtained in air.     

Modelling of erosion-corrosion in practical geometries

The limiting factor in certain instances of erosion-corrosion of steel is the presence of dissolved oxygen in the solution and the transfer of this oxygen to the reacting surface. Computational Fluid Dynamics (CFD) can be used to calculate oxygen diffusion throughout the flow and its transfer to the reacting surface. This was used in a computational model to calculate wear and validated against experimental results, for the first time, of erosion-corrosion wear in a contracting-expanding geometry. It was found that in order to correctly predict erosion-corrosion wear, Sherwood number independent grids were required providing a new metric to evaluate turbulent erosion-corrosion modelling. The predicted wear profile matched very closely with experimental results and overall matching was very good. Downstream of the flow expansion, erosion-corrosion wear was under-predicted. The disparity is due to detached flow for most of this sector where under-predicted radial velocities decrease transfer of oxygen to the reacting surface. This under-prediction is apparent in the downstream section due to the larger relative magnitude of the radial velocity in this sector.     

Responses of dairy cows to supplemental rumen-protected forms of methionine and lysine.

Multiparous Holstein cows at six universities were utilized to examine effects of ruminally protected methionine and lysine on lactational performance. Three hundred and four cows began the study; 259 cows were included in the production analysis. Following a 21-d standardization period, cows received a basal diet of corn silage and ground corn supplemented with one of five dietary treatments, which were supplements of soybean meal or corn gluten meal, the latter with zero and three combinations of protected methionine and lysine (methionine; methionine and lysine; methionine and double (2x) lysine). Treatment effects were evaluated during early, mid, late, and total lactation (22 to 112, 113 to 224, 225 to 280, and 22 to 280 d postpartum, respectively). On a DM basis, ratios of forage to concentrate (50:50, 60:40, and 70:30) increased, and dietary CP (16.0, 14.5, and 13.0%) decreased during the three periods of lactation. Amount of amino acid supplementation also decreased (15, 12, and 9 g/d methionine; 20, 16, and 12 g/d lysine; and 40, 32, and 24 g/d 2x lysine) with period of lactation. Actual and least squares means for milk, FCM, and milk protein yields were greater for soybean than for corn gluten meal during early, mid, and total lactation. In addition, these variables responded linearly to lysine in early lactation. Response to lysine was quadratic during mid and total lactation for these variables. Differences in nutrient intake explained production responses to protein sources but not to lysine. Serum amino acid responses primarily reflected differences in dietary protein source and rumen-protected amino acid.     

Signal-to-noise ratios of array receiving systems with internal losses

A formulation of the signal-to-noise ratio (SNR) for a typical antenna array receiving system that is more complete than those now available in the literature is presented. In addition to the external noise accepted by the array, it includes all forms of internal noise generated by the lossy components of the system. Distinct measurable factors account for distinct noise sources. For the analysis, it is shown that the actual lossy system can be replaced by an equivalent lossless system with appropriate attenuators. The formulation is used to design the combining network that will optimize the receiving system SNR for signals incident from a given direction in the presence of a known external noise distribution. The theory is applied to a specific array antenna receiving system operating under a variety of noise conditions, internal as well as external. A discussion of some typical results is presented.     

Mutual Coupling in the Signal-to-Noise Ratio Optimization of Antenna Arrays

In terms of network parameters defined at the input terminals, expressions applicable to any array configuration are derived for the S/N ratio. The formulation is made in such a way that it becomes possible to account for coupling effects that arise from the geometry of the array and the current distributions on the elements of the array. Since the S/N ratio consists of the ratio of two Hermitians forms, known techniques are used for its optimization. Comparisons with simplified theories are given that demonstrate clearly the importance of mutual coupling in many cases. Numerical results for a 4-element circular array are included for two idealized noise temperature distributions. Applications of this theory to EMC fields are also mentioned.     

Simultaneous and successive processing and narrative speech.

To assess the relationships between simultaneous and successive processing and narrative speech, 60 3rd graders were administered measures of story recall and marker tests for simultaneous and successive processing. Two indices of complexity of syntactical organization loaded on the successive factor, while speed of speech output loaded on the simultaneous factor. The relationship between successive processing and syntactical complexity is consistent with predictions derived from A. R. Luria's (1966, 1973) psychological findings. The relationship between speed of speech output and simultaneous processing suggests that fluent story recall may be dependent upon the formation of a unifying gestalt embodying the relationships between different parts of the story. (French summary) (23 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Practical feed network design for antenna arrays

Computational procedures have recently been developed which accurately determine the excitation (including mutual coupling effects) at each element of a closely spaced array enabling it to perform in some desired manner. A procedure for designing a transmission-line feed network capable of realizing these required excitations is described. The result is a narrow-band feed system composed simply of a transmission line together with a small number of stubs. A comparison between theoretical and experimental results is given.