Beam-pointing errors of planar-phased arrays

The beam-pointing error of an(M + 1) times (N + 1)planar phased array is analyzed by the use of both analytical and Monte Carlo techniques. Simple formulas for the rms pointing error are obtained for uniform planar arrays with both uniform and Gaussian uncorrelated phase-error distributions and for any arbitrary scan angle.     

Invited review: Caseins and the casein micelle: Their biological functions,structures, and behavior in foods

A typical casein micelle contains thousands of casein molecules, most of which form thermodynamically stable complexes with nanoclusters of amorphous calcium phosphate. Like many other unfolded proteins, caseins have an actual or potential tendency to assemble into toxic amyloid fibrils, particularly at the high concentrations found in milk. Fibrils do not form in milk because an alternative aggregation pathway is followed that results in formation of the casein micelle. As a result of forming micelles, nutritious milk can be secreted and stored without causing either pathological calcification or amyloidosis of the mother’s mammary tissue. The ability to sequester nanoclusters of amorphous calcium phosphate in a stable complex is not unique to caseins. It has been demonstrated using a number of noncasein secreted phosphoproteins and may be of general physiological importance in preventing calcification of other biofluids and soft tissues. Thus, competent noncasein phosphoproteins have similar patterns of phosphorylation and the same type of flexible, unfolded conformation as caseins. The ability to suppress amyloid fibril formation by forming an alternative amorphous aggregate is also not unique to caseins and underlies the action of molecular chaperones such as the small heat-shock proteins. The open structure of the protein matrix of casein micelles is fragile and easily perturbed by changes in its environment. Perturbations can cause the polypeptide chains to segregate into regions of greater and lesser density. As a result, the reliable determination of the native structure of casein micelles continues to be extremely challenging. The biological functions of caseins, such as their chaperone activity, are determined by their composition and flexible conformation and by how the casein polypeptide chains interact with each other. These same properties determine how caseins behave in the manufacture of many dairy products and how they can be used as functional ingredients in other foods.     

Policosanol content and composition of wheat varieties as affected by environment

BACKGROUND: Policosanol (PC) is a mixture of high‐molecular‐weight aliphatic primary saturated alcohols which possesses cholesterol‐lowering properties. Literature on PC contents and compositions of wheat varieties is limited. The main objective of this study was to evaluate the effect of genotype and environment on PC content and composition in wheat grain. RESULTS: Grain samples were collected from three varieties, Jagger, Trego and Intrada, grown at three locations, Alva, Balko and Goodwell, OK, in 2005. Two sets of samples were obtained from Goodwell (irrigated and dryland samples). Total PC content and PC composition in whole wheat grain samples were determined using a gas chromatography system. PC contents of the whole wheat grain samples varied from 15.9 to 28.7 mg kg^?1. Tricosanol, tetracosanol, hexacosanol, octacosanol and triacontanol were the most abundant PC components. Within each location a significant variety effect was observed. There was also a significant location × variety random effect on PC content. CONCLUSION: A fundamental understanding of compositional variation in wheat grain requires multi‐environment testing of genotypes, perhaps over several years. This study is the first step towards achieving this goal by revealing significant genetic differences in a limited set of genotypes. Copyright © 2008 Society of Chemical Industry     

Efficacy of liquid feeds varying in concentration and composition of fat, nonprotein nitrogen, and nonfiber carbohydrates for lactating dairy cows

In trial 1, we evaluated the efficacy of a liquid feed (LF) containing cane molasses and corn steep liquor as carriers of suspended white grease (WG) without or with urea (U) or with soybean lipid (SL; a byproduct of soybean processing) compared with roasted soybeans plus tallow blended into respective concentrates in a 16-wk lactation study. The dry matter intake (DMI) and milk production for LF diets were either similar to or greater than respective controls, although SL decreased milk fat percentage. In trial 2, we compared LF without fat to LF plus WG or SL and also evaluated the dose response to increasing amount of LF + WG in a 16-wk lactation trial in which the LF products were added to respective total mixed rations. The DMI was increased and then decreased (quadratic response) with increasing LF + WG without a linear response. However, production of milk, protein, and fat increased linearly with corresponding quadratic responses, which we interpret to be a result of a limiting returns response from DMI and density of net energy for lactation. When LF plus SL was fed, milk fat percentage and yield decreased compared with the comparable amount of LF + WG. In a 12-wk lactation study (trial 3), we added 3.25 or 6.5% of the dry matter as LF (a different but generally similar product than the previous trials and without fat) to diets formulated to maintain comparable ruminal nonstructural carbohydrate digestibility by adding soybean hulls to decrease nonfiber carbohydrates (NFC) concentration; the 6.5% LF diet was without or with Rumensin (11.5 g/909 kg of dry matter). When 3.25% LF was added but NFC was decreased from 40 to 37%, cows increased DMI and production of milk fat. Adding Rumensin decreased DMI but maintained milk fat yield compared with its 6.25% LF control without Rumensin. In trials 1 and 3, apparent total tract nutrient digestibility was not affected by treatment. In conclusion, feeding LF at about 5% (trial 2, which contained WG, 1.6% added sugar) or 3.25% (trial 3, 1.7% added sugar) generally increased DMI and maintained or increased production of milk, protein, and fat.     

Longitudinal study of prevalence of Campylobacter jejuni and Campylobacter coli from turkeys and swine grown in close proximity

Eastern North Carolina is a major contributor to both turkey and swine production in the United States. In this region, turkeys and swine are frequently grown in close proximity and by common growers. To further characterize colonization of turkeys and swine with Campylobacter in such a setting, we investigated the prevalence of thermophilic campylobacters in eight paired operations involving turkey farms in close proximity to finishing swine farms. All 15 surveyed flocks and 15 herds were Campylobacter positive at one or more sampling times. Campylobacter was isolated from 1,310 (87%) of the 1,512 turkey samples and 1,116 (77%) of the 1,448 swine samples. Most (> 99%) campylobacters from swine samples were Campylobacter coli, found in 59 to 97% of the samples from the different herds. Both Campylobacterjejuni and C. coli were recovered from the turkey flocks (overall prevalences of 52 and 35%, respectively). Prevalence among flocks ranged from 31 to 86% for C. jejuni and 0 to 67% for C. coli, and both species were recovered from most flocks. Relative prevalence of C. coli was higher in young birds (brooders), whereas C. jejuni predominated in grow-out birds (P < 0.0001). The prevalence of C. coli in a swine herd was generally not a good predictor for prevalence of this species in the corresponding turkey flock. These findings indicate that even though turkeys and swine grown in proximity to each other were commonly colonized with thermophilic campylobacters, the relative prevalences of C. jejuni and C. coli appear to be host associated.     

Disassembly analysis through time estimation and other metrics

This paper examines the problem of assessing product ease of disassembly for recycling in light of the broader issue of manufacturability evaluation. The disassembly time estimation method outlined here is shown to provide one of several needed metrics for use during product design. Moreover, the ability to estimate process time provides the foundation upon which other metrics can be developed. The evaluation based on disassembly time is demonstrated on an electric drill example, and the difficulties associated with generating other disassemblability metrics are discussed.     

Producing maintainable software

The increasing cost of software maintenance has resulted in greater emphasis on the production of maintainable software. One method used to enhance the development of maintainable software is to employ complexity metrics as a technique for controlling software complexity. In order to control complexity, it is imperative to plan for increases in complexity levels from code generation to code implementation. This paper presents a study of complexity increases during the testing and debugging phases of the software life cycle. The metrics used to measure complexity are lines of code, unique operators, unique operands, data difficulty, Halstead's effort and cyclomatic complexity.     

Replay and testing for concurrent programs

Attention is given to the problems that arise during the testing and debugging cycle of concurrent programs because of their nondeterministic execution behavior, whereby multiple executions of a concurrent program with the same input may exercise different synchronization sequences and even produce different results. These problems are solved by using deterministic execution debugging and testing. The purpose of deterministic execution debugging to to replay executions of a concurrent program so that debugging information can be collected. Examples of semaphores and monitors are used to illustrate the approach and the process of designing replay tubes is described. The use of regression testing to see if earlier debugging and testing introduced new errors, is examined