Factors associated with colostral specific gravity in dairy cows

The objectives of this study were to identify factors associated with colostral specific gravity in dairy cows, as measured by a commercially available hydrometer (Colostrometer). Colostral specific gravity was measured in 1085 first-milking colostrum samples from 608 dairy cows of four breeds on a single farm during a 5-yr period. Effects of breed, lactation number, and month and year of calving on colostral specific gravity were determined, as were correlations between colostral specific gravity, nonlactating period length, and 305-d yields of milk, protein, and fat. For 75 multiparous Holstein cows, relationships between colostral specific gravity, colostral IgG1, protein, and fat concentrations, and season of calving were determined. Colostral specific gravity values were lower for Brown Swiss and Ayrshire cows than for Jersey and Holstein cows, and lower for cows entering first or second lactation than third or later lactations. Month of calving markedly affected colostral specific gravity values, with highest values occurring in autumn and lowest values in summer. In multiparous Holstein cows, colostral specific gravity was more strongly correlated with colostral protein concentration (r = 0.76) than IgG1 concentration (r = 0.53), and colostral protein concentration varied seasonally (higher in autumn than summer). Our results demonstrate that colostral specific gravity more closely reflects colostral protein concentration than IgG1 concentration and is markedly influenced by month of calving. These results highlight potential limitations of using colostral specific gravity as an indicator of IgG1 concentration.     

The effects of infrastructure and policy on e-business in Latin America and Sub-Saharan Africa

This study investigates experts' assessments of the pertinent factors affecting e-business in developing countries from a theory-based national infrastructure perspective. We surveyed experts (business people, academicians, and officials of governmental and non-governmental organizations) in e-business in Latin America (LA) and Sub-Saharan Africa (SSA). Our partial least squares analysis shows that experts believed that policies targeted specifically toward e-business are important in affecting e-business capabilities and in obtaining value from e-business, more so than non-specific general information and communication technologies (ICT) policies, which are not significantly influential. ICT infrastructure generally affects e-business capabilities, though this was not found to be the case in Brazil. Experts believed that national government institutions positively affect e-business value in SSA, but not in LA. Experts did not believe that commercial infrastructure significantly affects e-business value. This study theoretically and empirically distinguishes between two different dimensions of e-business outcomes: specific capabilities and value derived from e-business. It operationalizes the effects of national government institutions and commercial infrastructure on e-business outcomes and empirically tests for their effects. The study provides empirical support for conceptual arguments for the need of ICT policies specific to the needs of e-business.     

Long-term inhalable particles and other air pollutants related to mortality in nonsmokers

Long-term ambient concentrations of inhalable particles less than 10 microm in diameter (PM10) (1973- 1992) and other air pollutants-total suspended sulfates, sulfur dioxide, ozone (O3), and nitrogen dioxide-were related to 1977-1992 mortality in a cohort of 6,338 nonsmoking California Seventh-day Adventists. In both sexes, PM10 showed a strong association with mortality for any mention of nonmalignant respiratory disease on the death certificate, adjusting for a wide range of potentially confounding factors, including occupational and indoor sources of air pollutants. The adjusted relative risk (RR) for this cause of death as associated with an interquartile range (IQR) difference of 43 d/yr when PM10 exceeded 100 microg/m3 was 1.18 (95% confidence interval [CI]: 1.02, 1.36). In males, PM10 showed a strong association with lung cancer deaths-RR for an IQR was 2.38 (95% CI: 1.42, 3.97). Ozone showed an even stronger association with lung cancer mortality for males with an RR of 4.19 (95% CI: 1.81, 9.69) for the IQR difference of 551 h/yr when O3 exceeded 100 parts per billion. Sulfur dioxide showed strong associations with lung cancer mortality for both sexes. Other pollutants showed weak or no association with mortality.     

Computer simulation of effects of the pore size distribution on the kinetics of pressure-assisted final-stage densification

Most theoretical treatments of pressure-assisted densification of porous solids assume a single size for all pores. We remove this assumption and consider a distribution of pore sizes. Dissolution of intragranular pores by volume diffusion and dissolution of intergranular pores by grain-boundary diffusion are both treated. The evolution with time of pore size distributions is calculated for distributions that are initially described by log-normal and Weibull functions, and differences in predicted behaviours are discussed. The pore size distribution is then related to two important quantities: porosity and number of pores per unit volume. The assumption of a distribution of pore sizes is found to avoid certain unrealistic predictions obtained from models with a single pore size, such as abrupt disappearance of all pores and rapid approach to full density.     

Effect of hydrogen donors on polymer degradation

The thermal decomposition of hydrocarbon macromolecules, including polymers in solution, is influenced by the presence of hydrogen donors. Depending on the particular polymer, hydrogen donors may increase, decrease, or have no effect on degradation rate. We investigated the concentration effect of the hydrogen- (H-)donor, 6-hydroxy tetralin, on degradation of polystyrene (2 g/l) dissolved in mineral oil at 275°C. The time evolution of the molecular weight distribution (MWD) was determined by gel permeation chromatography of samples from the batch reactor. The data indicated that the H-donor decreases the polystyrene degradation rate. This is in contrast to the H-donor (tetralin) enhancement of degradation for poly(styrene–allyl alcohol) dissolved in a 1-butanol solution at 150°C. Because the reaction mechanism for polymer degradation involves radicals, we have developed continuous-distribution mass balances for polymers and radicals in the elementary reactions by treating molecular weight as a continuous variable. Based on reactions for initiation–termination, propagation–depropagation and H-abstraction, the model describes the various H-donor effects through relative values of rate coefficients.     

In vitro gas production profiles and fermentation end‐products in processed peas,lupins and faba beans

BACKGROUND: An experiment was carried out to establish whether using a pre‐compacting device (expander) changes the contribution of dry matter (DM) and degradative behaviour of peas, lupins and faba beans over the different fractions (non‐washable fraction, NWF; insoluble washable fraction, ISWF; soluble washable fraction, SWF). Samples of the entire concentrate ingredients (WHO ingredients) and their different fractions (NWF, ISWF and SWF) were subjected to three processes (Retsch milling, R; expander treatment, E; expander‐pelleting, EP) and their fermentation characteristics were evaluated using an in vitro gas production technique. RESULTS: In peas and faba beans, both the E and EP processes increased the size of the NWF (P < 0.05) and decreased the size of the SWF compared with the R process. The maximum fractional rate of gas production in the first phase of fermentation was higher in the E and EP samples than in the R samples (P < 0.05). In lupins and faba beans the E and EP processes shifted the pattern of fermentation towards a more glucogenic fermentation, as represented by a lower non‐glucogenic to glucogenic ratio (NGR). Ammonia production (NH₃‐N) in the E and EP samples was significantly (P < 0.05) lower than that in the R samples. CONCLUSION: It is concluded that the E and EP processes provide a certain level of protection against ruminal breakdown to dietary protein and shift the pattern of fermentation towards a more glucogenic fermentation. Copyright © 2008 Society of Chemical Industry     

嵌入存储器时需谨慎行事

技术在进步，时代在前进。移动 式电子产品的设计人员早己不再依靠购买现成的芯片来组装系统了。现在，许许多多的移动装置制造商都在自己开发芯片。实际上他们只是开发自己的网表，而芯片的实际制造则完全交给半导体制造商去进行。随着微电子技术的进步，芯片中可以集成的线路，远远地超过逻辑线路的需要，还可以将存储器，模拟线路集成到同一芯片中。 将存储器集成到逻辑线路中己经是寻常之事，再增加一些模拟功能的线路，就可以初步实现长期追求的目标—一实现系统集成芯片。但是，在决定是否采用嵌入式存储器，嵌入什么样的存储器，以及…     

Theory of freezing: The inhomogeneous Ornstein-Zernike equation

We present a new freezing theory based on the inhomogeneous Ornstein-Zernike equation. The new theory is nonperturbative, in the sense that crystal and liquid are treated at the same level of approximation. This is in contrast to the popular density functional theory of freezing, which uses the liquid as a reference state for perturbation theory. Due to the demanding nature of the numerical method, preliminary calculations are presented for a model problem — which, in the strictest sense, is unphysical — namely, the freezing of hard disks in two dimensions. We also explore a generalized Percus-Yevick closure appropriate for the crystal.Paper presented at the Tenth Symposium on Thermophysical Properties, June 20–23, 1988, Gaithersburg, Maryland, U.S.A.