Factors of variation influencing bulk tank somatic cell count in dairy sheep

Between January and December 2002, a total of 21,685 records for bulk tank milk somatic cell count (BTSCC) were obtained from 309 dairy ewe herds belonging to the Sheep Improvement Consortium in Castilla-Leon, Spain. Based on the first statistical model, ANOVA detected significant effects of herd, breed, month within herd, dry therapy, type of milking, contagious agalactia, and installations within machine milking on logBTSCC. A second statistical model was used on herds with machine milking to study the effect of the vacuum level and pulsation rate on BTSCC. Herd and month within herd were important variation factors as they explained 48.4 and 16.1% of the variance in BTSCC. Variability in logBTSCC among breeds ranged from 5.84 (Castellana) to 6.09 (Awassi and Spanish Assaf). Implementing dry-ewe therapy (5.91) significantly reduced logBTSCC compared with when it was not implemented (6.10). Hand milking elicited greater logBTSCC (6.07) than machine milking (5.94). Machine milking of ewes in milking parlors (logBTSCC: 5.88 to 5.94) was associated with better udder health than was the use of bucket-milking machines (6.04). Reduced vacuum levels and elevated pulsation rate during machine milking optimized BTSCC. In all cases, clinical outbreaks of contagious agalactia increased BTSCC. As a result, dry therapy was proposed as the main tool to reduce BTSCC. Optimization of milking-machine standards and parlor systems also improved udder health in dairy sheep.     

New Techniques for Regular Expression Searching

We present two new techniques for regular expression searching and use them to derive faster practical algorithms. Based on the specific properties of Glushkov’s nondeterministic finite automaton construction algorithm, we show how to encode a deterministic finite automaton (DFA) using O(m2^m) bits, where m is the number of characters, excluding operator symbols, in the regular expression. This compares favorably against the worst case of O(m2^m|Σ|) bits needed by a classical DFA representation (where Σ is the alphabet) and O(m2^2m) bits needed by the Wu and Manber approach implemented in Agrep. We also present a new way to search for regular expressions, which is able to skip text characters. The idea is to determine the minimum length ℓ of a string matching the regular expression, manipulate the original automaton so that it recognizes all the reverse prefixes of length up to ℓ of the strings originally accepted, and use it to skip text characters as done for exact string matching in previous work. We combine these techniques into two algorithms, one able and one unable to skip text characters. The algorithms are simple to implement, and our experiments show that they permit fast searching for regular expressions, normally faster than any existing algorithm.     

New Techniques for Regular Expression Searching

We present two new techniques for regular expression searching and use them to derive faster practical algorithms. Based on the specific properties of Glushkovs nondeterministic finite automaton construction algorithm, we show how to encode a deterministic finite automaton (DFA) using O(m2^m) bits, where m is the number of characters, excluding operator symbols, in the regular expression. This compares favorably against the worst case of O(m2^m||) bits needed by a classical DFA representation (where is the alphabet) and O(m2^2m) bits needed by the Wu and Manber approach implemented in Agrep. We also present a new way to search for regular expressions, which is able to skip text characters. The idea is to determine the minimum length of a string matching the regular expression, manipulate the original automaton so that it recognizes all the reverse prefixes of length up to of the strings originally accepted, and use it to skip text characters as done for exact string matching in previous work. We combine these techniques into two algorithms, one able and one unable to skip text characters. The algorithms are simple to implement, and our experiments show that they permit fast searching for regular expressions, normally faster than any existing algorithm.     

Shrinkage control in a photopolymerizable hybrid solgel material for holographic recording

We report the correction of the shrinkage observed during UV postrecording curing in a holographic solgel material that was recently achieved by the use of various chemical formulations for the composition of the hybrid supporting matrix. We found that a chemical modification of the matrix noticeably attenuates the shrinkage (from 1.3% to 0.4% of the material's initial thickness with the inclusion of just 20% tetramethylorthosilicate), providing a material with improved stability for permanent data storage applications. The holographic properties of samples with different binders are also reported. In addition, a theoretical study has revealed the way by which to compensate for angular deviation in the Bragg condition during UV postrecording by tailoring the binder shrinkage (s), the maximum refractive-index modulation capability of the photosensitive mixture (deltan), or both.     

Effects of selective and complete dry therapy on prevalence of intramammary infection and on milk yield in the subsequent lactation in dairy ewes

The study was carried out in a commercial flock on 286 Churra breed ewes (566 half-udders) assigned to three lots depending on the type of antibiotic dry therapy received in the lactation previous to the one studied. One-hundred-and-four ewes were given complete therapy in all udders, 103 received selective therapy of infected half-udders, and 79 received no therapy at all. Half-udders of all animals were sampled for bacteriological study at < or = 72 h (lambing), 60 d, 120 d, and 155 d (drying-off) post partum. Dry therapy, parity number, lactation stage and therapy x parity interaction contributed significantly to variation in intramammary infection prevalence. Antibiotic dry therapy had the most significant effect. Prevalence during the whole of the subsequent lactation was significantly lower in lots receiving complete (18.8%) and selective (15.6%) dry therapy than in the untreated control lot (48.3%). Coagulase-negative staphylococci and streptococci (in particular Streptococcus agalactiae) were the organisms most significantly affected by dry therapy. In untreated ewes, prevalence increased noticeably from the 2nd to the 6th and subsequent lactations, but no significant changes were observed in the treated lots. Milk yield in the dry treated lots was 6.9% higher that in the untreated one. It was concluded that complete and selective treatments of ewes at drying-off were efficient and comparable methods of reducing the intramammary infection prevalence, improving bacteriological quality of milk, and increasing milk yield.     

Phonon effects on optical bistability in a two-photon resonantabsorber

Single beam two-photon optical bistability in a Fabry-Perot cavity is analyzed taking into account phonon effects. The Maxwell-Bloch equations of the system are further coupled by a term that is dependent on the electron-phonon interaction. It is shown that such an interaction can lead to a new type of optical bistability which competes with the ordinary absorptive one     

Thermal degradation of partially carboxymethylated cellulose grafted with 4-vinylpyridine

Partially carboxymethylated cellulose (PCMC) was grafted with 4-vinylpyridine (4-VP) using ceric ammonium nitrate (CAN) as initiator and the thermal behaviour of the grafted samples having different grafting yields was studied by means of thermogravimetric dynamic analysis (TGA). For comparison, the thermal behaviour of poly(4-vinylpyridine), P(4-VP), and the ungrafted cellulosic substrate were also examined. The activation energies were determined according to the Broido method. From the thermogravimetric curves the temperature range at which the main decomposition occurred was determined and showed that the thermal degradation of grafted samples was initiated at lower temperature than both PCMC and P(4-VP).     

Classification of EEG Spatial Patterns with a Tree-Structured Methodology: CART

The increasing use of computers in statistics has spawned a new generation of multivariate statistical techniques. Chief among these is a tree-structured approach to classification and regression analysis. The CART, or Classification and Regression Trees, program implements a recursive partitioning procedure based on an iterative search for best binary "splits" of data. Resultant classifiers consist of binary trees whose leaves determine class labeling. Extensive use of data resampling techniques replaces biased classifier performance measures.