Toxoplasmosis in goats in the Netherlands: a pilot study

A pilot-study was carried out on ten Dutch goat farms to see whether there is a relationship between farm management factors and the occurrence of toxoplasmosis. Questionnaires were used to collect information about farm management factors and blood samples were taken to determine the prevalence of toxoplasmosis on these farms. The mean prevalence was 47% (range 5-90%). The presence of kittens on a farm was a risk factor for a higher prevalence of toxoplasmosis.     

A note on the stability of CSDT methods for solving parabolic equations

In this note we study the stability aspects of CSDT methods for solving parabolic partial differential equations. We define two types of stability and discuss the stability of various CSDT methods.     

Crosstalk Loss Requirements for PCM Transmission

We present in this paper a unified approach to the crosstalk interference problem arising in PCM transmission on paired cables. For bipolar signaling, and three types of commonly used channel shaping, viz., cosine, raised cosine, and Gaussian, we present the minimum average near-end crosstalk (NEXT) and far-end crosstalk (FEXT) loss requirements at any transmission rate as a function of repeater spacing and number of interfering pairs so as to meet a desired error rate objective. This will aid in indicating if new cables need to be developed for a proposed rate of transmission or, for a given cable, the error margin available for degradations other than crosstalk can be readily determined. Extension to other coding schemes is indicated, and crosstalk compatibility is examined for mixedTsystems, such asT1,T1C, andT2. Graphical results are presented to readily aid in system design of anyTcarrier with repeater spacings up to 70 dB.     

The uptake of 3-deoxy-3-fluoro-D-glucose by synaptosomes from rat brain cortex

D-[3-3H]-3-deoxy-3-fluoroglucose was synthesized chemically and shown to be transported into rat brain synaptosomes by a saturable process with a Km 6.2 x 10(-4) M and a Vmax 2.8 nmole x mg protein-1. After an initial, rapid period of transport, further uptake of the fluorosugar is restricted by the rate of its phosphorylation. Both D-glucose and cytochalasin B are competitive inhibitors of 3-deoxy-3-fluoro-D-glucose transport with Ki values of 93 micron and 6.0 x 10(-7) M, respectively. Phloretin, N-ethylmaleimide and p-chloromercuribenzoate also inhibit the fluorosugar uptake, whereas ouabain and changes in K+, Na+, Mg2+ and Ca2+ ions have only a small effect. The recorded 3-deoxy-3-fluoro-D-glucose influx is slightly reduced by potassium cyanide, antimycin A, 2,4-dinitrophenol, and rotenone. The uptake reduction caused by these four reagents is relieved by the addition of exogenous ATP. The possible influence of hexokinse activity on the uptake process is discussed.     

Factors which affect the relative contributions of ovarian and uterine arteries to the blood supply of reproductive organs in guinea pigs

The establishment and stability of the behavioral baseline for rats in relation to the schedule of differential reinforcement of low rate under water reinforcer (DRL 20 sec for water) were studied, with the following results: When the DRL value was gradually stepped up from 1 sec to 20 sec with the advance of the sessions from 1to 16, the establishment of the behavioral baseline was slower than when DRL 20 sec was applied from the start. The establishment of the baseline was clearly accelerated by the prolongation of the length of time for training in one session from 60 min to 120 min. The baseline remained highly stable without being affected by the intermittent administration (2-3 times a week) of methamphetamine and diazepam, each in doses from 0.06 to 1.0 mg/kg, and of caffeine and pentobarbital, each in doses from 1.2 to 20 mg/kg, or by the discontinuation of the test from 1 to 15 days. However, during the retraining period following the test discontinuation it was found that the baseline fluctuated for a long time due to the elimination of water deprivation. The baseline stability, once established, could be maintained through about 300 daily sessions, with only a slight dependence on the change in environmental conditions such as humidity, temperature, and the season.     

“Meandering” Effects on the Diffusion of Continuous Dye Plumes in Coastal Currents

Experimental data on the diffusion of fluorescent dye plumes were obtained in the nearshore zone of the Great Lakes. The transport and diffusion of continuous dye plumes may be studied either in a frame of reference moving with the centre of gravity of the plume or in a frame of reference fixed to the stationary source. Conventionally, the former is referred to as “relative” diffusion and the latter as “absolute” diffisuion. The inter-link between the two concepts is explained by the random movements of the centre of gravity of the diffusing dye plume usually referred to as the “meandering”.In the past, experimental data from continuous dye plumes in coastal currents have been used to study “relative” diffusion, neglecting the random movements of the centre of gravity. In reality, however, “meandering” appears to be a more efficient agency than “relative” diffusion from the practical point of view of dispersing effluents over larger volume of the water body.In the present analysis, particular attention is given to delineate the two component physical processes of “relative” diffusion and “meandering” diffusion, by extended sampling of the dye plume to cover time scales of both the processes. Calculated horizontal eddy diffusivity K_y in “absolute” diffusion is greater by a factor of 2 as compared to “relative” diffusion. Very high peak/mean concentration ratios observed as the centre of the plume are a direct result of “meandering” due to large scale turbulent eddies.