Detection of serum antibody responses in cattle with natural or experimental Neospora infections

Parasite-specific antibody responses were detected using an indirect fluorescent antibody (IFA) test in cattle that were naturally or experimentally infected with Neospora parasites. The test was developed using Neospora tachyzoites isolated from an aborted bovine fetus and grown in bovine cell cultures (isolate BPA1). In all cases, infections were confirmed by the identification of Neospora tachyzoites and/or bradyzoite cysts in fetal or calf tissues using an immunoperoxidase test procedure. Fifty-five naturally infected cows that aborted Neospora-infected fetuses had titers of 320-5,120 at the time of abortion. The titer of 6 cows that were serologically monitored over a prolonged period decreased to 160-640 within 150 days after they aborted infected fetuses. Two of the cows showed an increase in their Neospora titers during their subsequent pregnancy, and they gave birth to congenitally infected calves that had precolostral titers of 10,240-20,480. Postcolostral titers of these calves and of 4 other calves with congenital Neospora infections were all > or = 5,120, whereas calves with no detectable parasites had titers < or = 160. Two pregnant heifers that were experimentally infected with the BPA1 isolate at approximately 120 days gestation seroconverted to Neospora antigens within 9 days and developed peak titers of 5,120 and 20,480 within 32 days of infection. The fetus taken by caesarean section 32 days postinfection from 1 heifer and the full-term calf born to the other had Neospora titers of 640 and 10,240, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)     

Laser turn-on delay and chirp noise effects in Gb/sintensity-modulated direct-detection systems

This paper describes a new IM/DD optical transmission system simulation which incorporates the impact of laser diode stochastic turn-on effects on system performance. Using this simulation, experimentally observed error rate floors, due to inappropriate laser diode biasing, can be theoretically modelled and predicted, for the first time     

Dielectric measurements using a rational function model

A recently proposed rational function model for the aperture admittance of 50 ohm Teflon filled coaxial lines in contact with a homogeneous dielectric is experimentally validated. A calibration technique of the automatic network analyzer utilizing standard terminations and time domain gating is used. Uncertainties in the dielectric properties of reference liquids do not enter the calibration procedure. Experimental results for water and methanol are compared with estimated values. A model expression for the sensitivity of the probe is validated. The sensitivities of two coaxial line probes for the measurements made are determined. Results obtained using the new model are compared with those of other workers     

Fast restoration of ATM networks

Asynchronous transfer mode (ATM) is now well recognized as the fundamental switching and multiplexing technique for future broadband ISDN. As these networks will be increasingly relied upon for providing a multitude of integrated voice, data, and video services, network reliability is a key concern. There are several intrinsic features of ATM networks that could potentially be exploited to provide improved restoration techniques, beyond those established for synchronous transfer mode (STM) networks, such as digital cross-connect restoration or self-healing rings. These features include ATM cell level error detection, inherent rate adaptation and nonhierarchical multiplexing. The authors explore the use of these features in developing fast restoration strategies for ATM networks. In particular, they address: (1) ATM error detection capabilities for enhanced failure detection, (2) network rerouting strategies, (3) spare capacity allocation, and (4) network control architecture and related implementation aspects. Their findings suggest that fast network span failure detection and bandwidth-efficient rerouting capabilities can be combined to develop restoration strategies for ATM networks with significantly greater performance-cost ratios when compared to existing STM network restoration strategies     

Monte Carlo simulation of grain growth and recrystallization in polycrystalline materials

The prediction and control of metal grain structures during processing have been major objectives of materials science. However, methodologies that are accurate and can be easily generalized to a variety of processing conditions have been difficult to formulate due to the complexity of the grain interactions. A novel Monte Carlo-based approach that explicitly incorporates these interactions has been developed to simulate the microstructural evolution driven by the minimization of grain boundary energy and lattice defect density. The applicability of this procedure has been demonstrated by the good correspondence between simulation results and experimental observations. This article reviews recent advances in the application of this technique to the investigation of a variety of phenomena, including normal and abnormal grain growth as well as static and dynamic recrystallization.     

Forming the optimal union of multiple databases

Many organizations, best illustrated by libraries, have access to hundreds of databases possessing varying degrees of complimentary and overlapping records. While users may receive positive marginal benefits from data duplications, all databases and their services cannot be supported because of resource limitations. This paper attempts to conceptualize the problem of database collection in an environment of multiple databases, with differential content and performance characteristics, diverse users, and limited resources. It defines the database collection problem as a constrained zero-one integer programming problem and solves for the optimal combination or union of databases. Several extensions are shown, where special conditions are imposed on the relationships between databases and/or their availability.     

The effects of patterned calorie-restricted diets on mammary tumor incidence and plasma endothelin levels in DMBA-treated rats

Chronic caloric restriction has been shown to inhibit mammary tumor promotion in the 7,12-dimethyl-benz[a]anthracene (DMBA) rat mammary tumor model. The objectives of this study were to determine (i) the effects of chronic caloric cycling (yo-yo dieting) on mammary tumor promotion by high fat diets and (ii) the effect of three dietary regimens +/- superimposed mammary tumor burden on plasma endothelin-1,2 (ET) levels. Female Sprague-Dawley rats were treated with DMBA (5 mg/rat) and divided into three dietary groups: ad libitum (AL) (containing 15% corn oil); 40% calorie restricted (CR) (containing 20% corn oil so consumption of fat was equivalent between AL and CR); a calorie cycled (CC) group fed alternatively AL and CR diets each 48 h period. After 10 weeks, tumor incidences were: AL, 63%; CR, 27%; CC, 57% (AL versus CR, P < 0.05; CC versus CR, P < 0.05; AL versus CC, NSD). ET levels (pg/ml plasma) were: AL, 16.0 +/- 6.54; CR, 32.31 +/- 0.34; CC, 23.44 +/- 5.04 (AL versus CR, P < 0.01; CC versus CR, P < 0.01; AL versus CC, P < 0.05). Plasma ET levels were independent of tumor incidence and tumor burden, but plasma ET levels were significantly increased in rats with a prior history of calorie restriction. As expected, maintained caloric restriction reduced mammary tumor incidence but intermittent caloric restriction (caloric cycling or yo-yo dieting) was without similar benefit.