Digital logic gate using quantum-Dot cellular automata

A functioning logic gate based on quantum-dot cellular automata is presented, where digital data are encoded in the positions of only two electrons. The logic gate consists of a cell, composed of four dots connected in a ring by tunnel junctions, and two single-dot electrometers. The device is operated by applying inputs to the gates of the cell. The logic AND and OR operations are verified using the electrometer outputs. Theoretical simulations of the logic gate output characteristics are in excellent agreement with experiment.     

Effects of Prolonged Exposure to Low‐Dose Fumonisin B1 in Pigs

From the point of view of human exposure, fumonisins (FB₁, FB₂, FB₃, FB₄), a relatively recently (1988) discovered and identified group of mycotoxins, represent one of the five most important mycotoxin groups causing human disease. In an earlier experiment studying the effects of relatively low doses (10, 20 and 40 p.p.m.) of FB₁ in weaned piglets, it was established that the 4‐week feeding of 10 p.p.m. (mg/kg feed) FB₁ produced mild pulmonary oedema. This suggested the importance of studies with even lower doses of the toxin to determine the tolerable limits. The objective of this experiment was therefore to study the effects of prolonged (8‐week) exposure to still lower concentrations (0, 1, 5 and 10 mg/kg feed) of FB₁. The 8‐week feeding of FB₁ in low concentrations (1–10 p.p.m.) did not cause clinical signs and significant performance impairment in pigs, but rendered irreversible the chronic changes that had already developed in the animals in a dose‐dependent manner. Dissection revealed pathological alterations of the lungs in one of the animals given 1 p.p.m. (n=4), in two animals exposed to 5 p.p.m. (n=5), and in three animals given 10 p.p.m. (n=4). In all three treatment groups, proliferation of the connective tissue fibres, primarily of those around the lymphatic vessels, in the subpleural and interlobular connective tissue of the lungs, extending to the peribronchial and peribronchiolar areas, was seen. The results of this experiment call attention to the risk of prolonged low‐dose toxin exposure, which has very important public health implications.     

Experimental Leptospira borgpetersenii serovar hardjo infection of pregnant cattle

Objective To observe the effect upon the foetus of experimental infection of pregnant cattle with Leptospira borg-petersenii serovar hardjo .
Design A disease transmission study using pregnant cattle.
Procedure Fourteen heifers serologically negative to L hardjo were artificially inseminated and later challenged with a north-Queensland isolate of L hardjo by conjunctival inoculation. The heifers were serologically monitored and their urine examined for the presence of leptospires using culture and fluorescent-antibody tests at appropriate intervals. Elective caesarean sections were performed on pregnant heifers at 6.5 weeks after the challenge. Foetuses were examined using serological, histopathological, microbiological and fluorescent-antibody tests.
Results Ten of the heifers became pregnant, but three subsequently aborted before challenge. After challenge, all 14 heifers seroconverted and L hardjo was isolated from the urine of 6 of the 7 pregnant heifers. No evidence of foetal L hardjo infection was detected. Two of the foetuses had histopatho-logical lesions consistent with Neospora s p infection.
Conclusion It is likely that the isolate of L hardjo used in this study does not normally infect the foetus. Neospora s p may be a more significant cause of bovine reproductive wastage.     

Encephalitis attributed to dactylariosis in Japanese quail chicks (Coturnix coturnix japonica)

Dactylaria gallopava was isolated from brain tissue of 1-to-3-week-old quail chicks. Successive batches demonstrated elevated (15-20%) mortality preceded by incoordination and lateral recumbency. Chicks exhibited cerebellar and cerebral encephalitis characterized by brown-red discoloration of affected brain tissue. Decontamination of setters and hatchers resulted in abrupt cessation of mortality in subsequent placements, implicating incubators as the source of infection.     

Evaluation of an Artificial Insemination Programme in a Seasonal Breeding Dairy System through Milk Progesterone

In order to evaluate an artificial insemination programme and reproductive efficiency of dairy herds in Uruguay, a survey was conducted with five dairy farms, utilizing a total of 768 lactating Holstein cows. Precision of oestrous detection was assessed by one milk progesterone sample taken on day of breeding and was 11.1%. Two additional samples taken at day 10 and 23 were used to confirm ovulation and early pregnancy. Accuracy of pregnancy estimation by milk progesterone was 70.4%. Reproductive efficiency was determined by the analysis of records. Average intervals from calving to first service were 101 days and to conception 132 days and these were affected by parity, body weight and body condition at calving, but not at breeding, or by milk production. Oestrous detection rates and pregnancy rates were 37.5 and 15.6%, respectively. It was concluded that losses in reproductive efficiency in dairy farms of Uruguay in a seasonal artificial insemination programme were mainly due to unobserved heats, rather than incorrect oestrous detection.     

Methods of inoculating Acer spp., Populus tremuloides, and Fagus grandifolia logs for commercial spalting applications

One of the most promising wood value-added processes currently under development is spalting, where pigment is added to wood via fungal colonization. Previous studies have shown laboratory level spalting to be achievable and highly predictable. However, large-scale spalting for potential commercial applications introduces a substantial number of additional variables which impact the spalting process. To test the potential of commercial-scale spalting, Acer saccharum, Fagus grandifolia, and Populus tremuloides logs were inoculated with multiple known spalting fungi utilizing both liquid spray cultures and live dowel pin cultures. Many of the fungi that successfully produce spalting in small, sterile cultures also produced significant amounts in large logs, with many spalting patterns identical to those found in small-scale testing. Pairings of Trametes versicolor/Scytalidium cuboideum and Xylaria polymorpha/Xylaria polymorpha (different isolates) produced significant amounts of zone lines. In addition, the method of inoculation impacted the amount of spalting: more zone lines were produced when fungi were introduced via plugs, while more stain was produced when liquid cultures were sprayed onto the logs. These results indicate that many of the standard spalting fungi are suitable for large-scale applications; however, the inoculation method appears to be a vital component for successful spalting under a restricted time schedule.     

Etiology and pathogenesis of necrotic enteritis

Sporulated oocysts ofEimeria acervulina were administered orally to cage-housed broilers at a dose of 3.5×10⁵ resulted in mild subclinical coccidiosis.Clostridium perfringens incorporated in feed at a level of 2.5×10⁸ organisms/g. produced lesions characteristic of necrotic enteritis. Mortality of 8% (7/80) occurred in birds fed a ration inoculated withCl. perfringens alone. Mortality of 35% (28/80) was observed in birds which received an oral dose ofE. acervulina and which were fed simultaneously with a ration containingCl. perfringens. Birds which were fed an inoculated ration two days after an oral dose ofE. acervulina showed 41% (33/80) mortality. Birds which received an inoculated ration for two days before administration of an oral dose ofE. acervulina demonstrated 18% mortality (15/80). Birds which were fed an inoculated ration four days after an oral dose ofE. acervulina showed 10% mortality. Infection withE. acervulina reduced the pH of intestinal contents with a simultaneous depression in serum protein. A 39% increase in intestinal passage time from 178 to 248 minutes occurred on the fifth day after infection withE. acervulina. These experiments suggest that necrotic enteritis, attributed to proliferation of a toxigenic strain ofCl. perfringens, followed intestinal stasis and minimal lesions induced by mild intestinal coccidiosis.