Arteriovenous malformation or contusion : a diagnostic dilemma.

A young man was involved in a motor vehicle accident and sustained cerebral contusion in the right frontal and occipital lobes. Computed tomography (CT) scan done 2 weeks after the injury revealed multiple serpenginous structures which enhanced following intravenous contrast media administration. The possibility of arteriovenous malformation (AVM) was raised and angiography was suggested. However, he was managed conservatively and a repeat CT scan 4 months post trauma revealed encephalomalacia in the right frontal and occipital lobes with no more surrounding enhancement. The cause for the multiple serpenginous enhancement demonstrated previously confirmed those are areas of hyperperfusion in healing surface brain contusion. The aim of this case report is to discuss on the possible causes of focal enhancement following head injury versus the features of AVM on plain and post contrast CT scan with the effort to clear the doubt and to avoid future confusion.

Experimentally determined relationship between extinction coefficients and liquid water content.

Simultaneous environmental chamber measurements have been made of 10.27-microm extinction coefficients and liquid water content of droplet distributions with sizes spanning those of light to heavy fogs. The measurements yield a linear relation that is nearly independent of droplet size distribution, in agreement with recent calculated results and predictions. Liquid water content varied from 0.01 to 3.3 g/m(3), and droplet size distributions with both single and bimodal differential extinction coefficient curves were included. The spectral variation of the extinction ceofficient between 9.2 and 10.8 microm was also measured. The results are in good agreement with the variation calculated for typical droplet size distributions.

Infrared optical properties of diesel smoke plumes.

Far IR optical properties have been measured for smoke from diesel fires. Concentrations of both gaseous and particulate combustion products have been measured and chemical species contributing to the optical effects identified. To obtain these results, a variety of sampling instruments were lofted into large plumes on a mobile and open structure. The smoke plumes of diesel fires have been found to consist largely of carbonaceous material (in fibrous form) and heavy liquid hydrocarbons infused with the expected gaseous products of the combustion process. Strong attenuation at a wavelength of 10.6 microm is found to be due largely to the carbonaceous aerosol. The absorption coefficient is typically ~500 km(-1) at 10 m from the source with a variable but often comparable total scattering coefficient. The extinction coefficient, normalized to the mass density of the aerosol in a unit volume of space, is found to be 1.2 m(2)-g(-1) with an estimated variance of 20%. luctuational spectra of the attenuation follow a form similar to turbulence spectra.