Effects of tallow in diets based on corn silage or alfalfa silage on digestion and nutrient use by lactating dairy cows

Six multiparous Holstein cows (average 31 days in milk; 36.3 kg/d of milk) fitted with ruminal cannulas were used in a 6 x 6 Latin square with 21-d periods to investigate the effects of diets that varied in forage source and amount of supplemental tallow. Isonitrogenous diets in a 2 x 3 factorial arrangement were based on either high corn silage (40:10 corn silage to alfalfa silage, % of dry matter) or high alfalfa silage (10:40 corn silage to alfalfa silage, % of dry matter) and contained 0, 2, or 4% tallow. Intakes of dry matter and total fatty acids were lower when cows were fed the high corn silage diet. Tallow supplementation linearly decreased dry matter intake. Milk yield was unaffected by diet; yields of milk fat and 3.5% fat-corrected milk were higher for the high alfalfa silage diet but were unaffected by tallow. Milk fat percentage was higher for the high alfalfa silage and tended to decrease when tallow was added to the high corn silage diet. Contents of trans-C18:1 isomers in milk fat were increased by high corn silage and tallow, and tended to be increased more when tallow was fed in the high corn silage diet. Ruminal pH and acetate:propionate were lower when high corn silage was fed. Ruminal acetate:propionate decreased linearly as tallow increased; the molar proportion of acetate was decreased more when tallow was added to the high corn silage diet. Ruminal liquid dilution rates were higher for the alfalfa silage diet; ruminal volume and solid passage rates were similar among diets. Total tract apparent digestibilities of dry matter, organic matter, crude protein, starch, energy, and total fatty acids were unaffected by diet. Digestibilities of neutral detergent fiber, acid detergent fiber, hemicellulose, and cellulose were lower when high corn silage was fed. The high alfalfa silage diet increased intakes of metabolizable energy and N, and increased milk energy and productive N. Tallow decreased the amount of N absorbed but had few other effects on utilization of energy or N. Tallow linearly increased concentrations of nonesterified fatty acids and cholesterol in plasma; cholesterol was increased by high alfalfa silage. Overall, forage source had more pronounced effects on production and metabolism than did tallow supplementation. Few interactions between forage source and tallow supplementation were detected except that ruminal fermentation and milk fat content were affected more negatively when tallow was fed in the high corn silage diet.     

Adaptation of urban water supply infrastructure to impacts from climate and socioeconomic changes: The case of Hamilton,New Zealand

While the relations between climate variables and sectoral water demand have been well established in the literature, few studies have attempted to quantify changes in urban water usage with climate change. Concentrating on the city of Hamilton, New Zealand, we investigate possible water use and infrastructure needs for a range of climate and population projections. We find that water demand (at the monthly aggregate level) is largely driven by changes in population, and not significantly affected by changes in climate. However, as population increases, the effect of climate variables on per capita consumption will be magnified. Monthly aggregate changes may further mask potenially significant short-term shortages. In several scenarios, water supply shortages in 2030 occur with a 30--40% probability, suggesting needs for long-term capacity expansion or aggressive demand side management, rather than implementation of short-term management of water demand.     

Volatility in the geographical structure of short-run US interstate migration

"Migration is often thought to be a long-run phenomenon. However, it is shown here by means of labor-force migration estimates derived from the Continuous Work History Sample over the period 1958-1975, that US interstate migration is quite volatile over the short run with respect both to its adjustment to macroeconomic fluctuations and to its geographic structure. A hierarchical clustering routine is utilized to analyse yearly estimates of interstate gross in-migration and out-migration so as to identify the temporal stability and characteristics of the geographical patterns of migration. States enter the national migration linkage tree at different levels for different years, depending upon the level of short-run economic activity." It is also shown that "when national economic conditions worsen, labor-supply adjustments are more localized and the degree of interstate interdependence is less than in times of economic boom."     

Oxidation of commercial purity titanium

The oxidation kinetics of commercial purity Ti-A55 exposed to laboratory air in the 593–760°C temperature range were continuously monitored by thermogravimetric analysis. The oxide thickness was measured by microscopy and the substrate contamination was estimated from microhardness measurements. The microhardness depth profiles were converted to oxygen composition profiles using calibration data. The oxygen diffusion coefficient in alpha-Ti appears to be approximately concentration independent in the 1–10 at. % oxygen range. The combination of an “effective diffusion coefficient” and an “effective solubility” at the oxide-metal interface usefully describes the diffusion process over the entire composition range. A model for the total parabolic oxidation kinetics, accounting for the two individual components, oxide growth and solid solution formation, has been proposed. Diffusion coefficient for oxygen in TiO₂ has been estimated as a function of temperature and is found to be about 50 times the value in alpha-Ti. The metallographically prepared cross-sections of the oxidized specimens revealed a “moving boundary” in the substrate, parallel to the oxide-metal interface. This boundary was associated with a specific oxygen level of 5.0±0.5 at.%. It occurred at a distance from the oxide-metal interface which was correlatable with temperature and time of exposure. The diffusion coefficient corresponding to the composition of this moving boundary is in excellent agreement with the effective diffusion coefficient for the substrate contamination.     

Oxidation and embrittlement of Ti-6Al-2Sn-4Zr-2Mo alloy

Ti-6Al-2Sn-4Zr-2Mo titanium alloy is a candidate material for multiwall thermal protection system concepts for advanced space transportation system vehicles. The total oxidation kinetics for this alloy, exposed to laboratory air in the 593–760°C range, were monitored by thermogravimetric analysis. The oxide thickness was measured by microscopy and the substrate contamination was estimated from microhardness measurements. Tensile elongation was determined for selected foil specimens after exposure to simulated space shuttle reentry conditions. The variation of total weight gain with time was found to have two distinct parabolic stages separated by a transient region. This transient was due to a process which involved an increase in the parabolic growth rate constant for the oxide and a simultaneous increase in oxygen solubility at the oxide metal interface. The time dependent increase in oxygen solubility at the interface was from about 7 at. % in stage 1 to about 18 at. % in stage 2. The diffusion coefficient for oxygen in the alloy was determined as a function of temperature using the difference between the total weight gain in stage 1 and the corresponding weight gain due to oxide growth. A model for the total oxidation kinetics, accounting for the two individual components namely oxide growth and solid solution formation, is proposed. The activation energy for the diffusion of oxygen in the alpha-solid solution is shown to be roughly equal to the activation energy for the degradation of tensile elongation for the alloy in the foil gage condition.     

甲烷市场化合作计划——煤矿煤层气项目开发的机遇

煤矿煤层气的排放是全球甲烷排放的一个重要来源，“甲烷市场化合作计划”的发起是为了识别并开发相关的工程项目，减少煤矿、垃圾填埋场和石油天然气系统等各领域中的甲烷排放。煤矿煤层气项目是“甲烷市场化合作计划”的三个核心领域之一，对推动煤炭行业的甲烷减排发挥重要作用。     

Metabolism of arginine and ornithine in the cow and rabbit mammary tissue.

Amino acid uptake by the bovine mammary gland was determined by arteriovenous difference. Extraction of arginine from the plasma by the lactating bovine mammary gland was in excess of requirements for milk protein synthesis. Ornithine and citrulline also were extracted by the gland but are not in milk protein. Incubations of slices of lactating mammary tissue from cows and rabbits indicate that nonessential amino acids, especially proline and glutamate, are the major end products of arginine and ornithine metabolism in the lactating mammary gland.     

NIRA: A New Inter-Domain Routing Architecture

In today's Internet, users can choose their local Internet service providers (ISPs), but once their packets have entered the network, they have little control over the overall routes their packets take. Giving a user the ability to choose between provider-level routes has the potential of fostering ISP competition to offer enhanced service and improving end-to-end performance and reliability. This paper presents the design and evaluation of a new Internet routing architecture (NIRA) that gives a user the ability to choose the sequence of providers his packets take. NIRA addresses a broad range of issues, including practical provider compensation, scalable route discovery, efficient route representation, fast route fail-over, and security. NIRA supports user choice without running a global link-state routing protocol. It breaks an end-to-end route into a sender part and a receiver part and uses address assignment to represent each part. A user can specify a route with only a source and a destination address, and switch routes by switching addresses. We evaluate NIRA using a combination of network measurement, simulation, and analysis. Our evaluation shows that NIRA supports user choice with low overhead.     

Using Electronic Surveys in Organizational/Employee Communication Research: A Study at GE's Global Research Center

This study explores methodological issues that communication scholars and practitioners face when administering electronic surveys within for-profit organizations. In 2000, the researchers conducted a series of three cross-sectional studies within General Electric's (GE) Global Research Center. The Center is located in Niskayuna, NY. An equivalent version of a communication survey was administered electronically to a random stratified sample of GE employees three times that year. Each employee sample was subject to a different survey intervention: no intervention, follow-up reminder email only, and leader pre-announcement email plus a follow-up reminder. The researchers also recorded how long it took respondents to return their surveys. The highest response rate (41%) occurred in the third intervention. Across the three administrations, 465 GE employees completed the surveys; 98% of respondents returned their surveys electronically rather than printing out their responses and sending them to the researcher by postal mail. The article concludes with implications and suggestions for those who administer electronic surveys within organizations.     

Stationary, nonstationary, and hybrid iterative method of momentssolution schemes

The purpose of this paper is to report on the convergence rates of two iterative matrix solution methods individually and then to combine the two methods into a hybrid scheme to achieve additional convergence rate benefits. One iterative matrix solver investigated is the sparse iterative method (SIM) which is a stationary, Jacobi-like solver but uses a sparse and not a banded matrix, with matrix elements corresponding to strong interactions, rather than position in the matrix. In this paper, the SIM is modified to include an adaptive relaxation scheme to improve its convergence speed and numerical stability. Another iterative scheme investigated is the nonstationary biconjugate gradient stabilized (BiCGSTAB) method. It is shown that the BiCGSTAB is considerably improved when the method is preconditioned by the sparse matrix used in the SIM method. Finally, a hybrid scheme is proposed which combines both SIM-AR and BiCGSTAB-precon and it is shown that the hybrid gives best results on the problems considered. Examples giving convergence time versus accuracy are presented for two problems: a wire-grid plate, and a wire-grid partial helicopter