Epidemiology of bluetongue in Central America and the Caribbean: initial entomological findings. Regional Bluetongue Team

Forty-four species of Culicoides (Diptera: Ceratopogonidae) were caught in insect light traps during the first 2 years of studies on the epidemiology of bluetongue virus in the Caribbean and Central America. Traps were operated near sentinel ruminants which were bled monthly for serologic evaluation and then virus isolation. More than 570,000 individuals were identified. Culicoides insignis Lutz accounted for 90% of the catch, C. filarifer Hoffman/C. ocumarensis Ortiz 5%, C. furens Poey 3% and C. pusillus Lutz 2%. Other species accounted for less than 1% of the total catch. Sentinel ruminants became seropositive when C. insignis populations were high at many study sites. At a few sites C. pusillus and C. filarifer/C. ocumarensis were predominant or were present in large numbers during seroconversions of sentinels. Virus isolations were obtained from sentinel ruminants during times when these same species were present in large populations.     

Ultrasonographic imaging of canine mammary tumours

Two-hundred-and-fifteen embryos recovered from 76 donor ewes from flocks endemically infected with sheep pulmonary adenomatosis (SPA) and mated with uninfected rams were transferred to 131 uninfected recipients under strict sanitary conditions using International Embryo Transfer Society protocols. The recipients and their progeny were kept in a closed, isolated SPA-free flock. Thirty-eight of 51 progeny from SPA-positive donors and 55 of 74 progeny from donors in which no lesions of SPA were detected survived for at least five years after birth. In a similar study 11 embryos from four uninfected donors mated to an SPA-infected ram were transferred to seven recipients, and four of five progeny born to four recipients survived for at least five years. No evidence of SPA was found in the recipients or their progeny by embryo transfer in either study. On the basis of clinical and pathological criteria, it is concluded that embryo transfer can be used to provide an effective barrier against the transmission of SPA from donors from infected flocks, whether or not the parents show clinical signs of the disease.     

Microbiological leaching of copper from lead mattes

The possibility of recovering copper from lead blast furnace mattes by bioleaching, using bacteria of the genus Thiobacillus ferrooxidans, has been studied. In this paper, the influence of certain variables on the dissolution rate and the adaptation period of the bacteria have been evaluated, including energy source, nutrient, type of matte, type of stirring, pulp density, and particle size. In addition, the influence of bioleaching for different periods of time, as a preparatory stage before chemical or biological leaching of the matte, was studied. The optimum conditions for recovery are achieved by way of the two-stage bioleaching process. The degradation of the solid caused by bacterial activity during the first stage is the reason for the high recovery during the second stage.     

The Determination of the Entrapment Efficiency for a Molecular Dispersion System

The entrapment of d-propoxyphene in ethyl cellulose pseudolatex systems was studied. Heat of fusion measurements were used to determine the extent of molecular scale entrapment. When δH_f = 0, the drug was assumed to he entrapped on a molecular level while δH_fvalues greater than zero indicated the presence of crystal structure. Zeta potential measurements were also used to indicate the point of maximum entrapment efficiency. A good correlation was obtained between zeta potential and heat of fusion measurements.     

Development of an autographic falling-weight impact system

The objective of this project was to develop a system that would allow the determination of the energy absorbed during fracture in a falling-weight impact test. Equipment was developed which would allow the force exerted by the impact tup on the specimen to be determined during the test. Using this information and the equations developed, it was possible to convert force-versus-time traces on an oscilloscope to energy absorbed. Tests were conducted to compare the autographic method with the normal falling-weight method. The system was shown to give results which are similar to results from normal falling-weight impact tests, but requires much fewer specimens. Tests can be made and results can be obtained on small sample sizes, since results are obtained for each specimen tested. Also, a more representative value of falling-weight impact strength can be determined in cases where there are mixed failure modes. The autographic system may be used in those instances where there are limitations of material, and with further use it may eventually replace the normal falling-weight impact determination.     

Prediction of equivalent environments by energy exchange and assessments of physiological strain and discomfort

The described equivalence postulate was confirmed experimentally by examining physiological responses as well as discomfort sensation in a series of predicted equivalent conditions during exercise (congruent to 3 met). ET or the equivalent Ta at 50% RH is a single independent variable that is uniquely related to the mean skin temperature (Tsk), skin wettedness (w), body core temperature (Tcore) and sense of discomfort.     

Evaluation of risk of deterministic effects in fluoroscopically guided procedures

A methodology for the evaluation of skin dose distribution and possible skin injuries on patients undergoing interventional procedures has been developed as part of the European DIMOND programme. Relevant dosimetric data from the procedures are recorded and other specific measurements for skin dose evaluation (slow films for therapy, radiochromic films, thermoluminescence dosemeters and optically stimulated luminescence dosemeters) have been carried out. For non-cardiac and for some cardiac procedures, dose-area product values of 200 and 300 Gy cm2 were proposed, respectively, as a trigger level for further detailed skin dose investigation and possible clinical follow-up. Results from a survey of 191 selected complex procedures are reported. Out of all the patients included in the trial, 16% received skin doses > or =1.5 Gy. No skin injuries were found in any of the patients followed.     

Sorting numbers in linear expected time and optimal extra space

An algorithm is shown that sorts n numbers, each representable in h bits, in θ(n) time on the average where the numbers to be sorted are selected randomly from some interval. The algorithm only uses θ(log n) bits of extra space, which is asymptotically optimal.     

New methods for the determination of hydrogen content of aluminum and its alloys: Part I. Improvements in the vacuum extraction method

The vacuum hot extraction method, first proposed by Ransley for the determination of hydrogen content of aluminum and its alloys, was systematically investigated to check if it could be considered as a reference procedure for the development of other methods directly applicable in routine work. For that, the use of an improved apparatus involving a mass spectrometer as gas detector and specimens intentionally charged with deuterium —a tracer whose properties are similar to those of hydrogen—permits the following conclusions: 1) The method is correct for any alloy, even for all the alloys with a high magnesium or zinc content, 2) The “getter effect” which could lead to inaccurate results does not occur, provided the pumping speed of the transfer pump exceeds the rate of outgassing from the sample, 3) The extraction from the solid phase seems to be complete, since results obtained in this condition are not significantly different from those obtained from melted samples. 4) The time required for an analytical determination (several hours) due essentially to the preliminary operations, cannot be practically reduced by extraction at higher temperature in the liquid state. The Ransley method can thus be considered as a reference method for checking other more practical methods.     

Multichannel restoration of single channel images using awavelet-based subband decomposition

We present a new matrix vector formulation of a wavelet-based subband decomposition. This formulation allows for the decomposition of both the convolution operator and the signal in the subband domain. With this approach, any single channel linear space-invariant filtering problem can be cast into a multichannel framework. We apply this decomposition to the linear space-invariant image restoration problem and propose a family of multichannel linear minimum mean square error (LMMSE) restoration filters. These filters explicitly incorporate both within and between subband (channel) relations of the decomposed image. Since only within channel stationarity is assumed in the image model, this approach presents a new method for modeling the nonstationarity of images. Experimental results are presented which test the proposed multichannel LMMSE filters. These experiments show that if accurate estimates of the subband statistics are available, the proposed multichannel filters provide major improvements over the traditional single channel filters.