SPECT, CT, and MRI in head injury: acute abnormalities followed up at six months

We report a case of cervicofacial necrotizing fasciitis that developed after blepharoplasty, an occurrence that, to our knowledge, has not previously been reported in the medical literature. A patient who presented to our institution 3 days after undergoing blepharoplasty of the upper eyelid was diagnosed as having fulminant fasciitis involving extensive areas of the face, scalp, and neck. We review the case in detail and discuss clinical and radiological clues to diagnosis, surgical and medical management, wound care, and subsequent scar contracture. This case emphasizes the need for individualized, appropriate postoperative care and for an awareness of this rare, potentially fatal complication. Early recognition and aggressive treatment of cervicofacial fasciitis can arrest its rapid progression and prevent devastating sequelae.     

Spatial-Semantic Display Processing: The Role of Spatial Structure on Recall

The purpose of the present study was to test a model of spatial-semantic display processing by comparing the aided and unaided recall of information presented in a node-link format (knowledge map) to the aided and unaided recall of information presented in a text format. Structural icons of the knowledge map and text with the verbiage removed were used to aid retrieval in some conditions. Participants were randomly assigned to one of eight groups formed by the complete crossing of three factors: knowledge map versus text, structural icon at recall versus no structural icon at recall, and immediate versus delayed recall. Knowledge map groups outperformed text groups on essay tests and they more accurately remembered where information was located within the materials. Both knowledge map and text icon-aided recall groups had significantly better performance than the no icon, unaided recall groups (particularly on main ideas).     

4- and 13-GHz tuned amplifiers implemented in a 0.1-μm CMOStechnology on SOI, SOS, and bulk substrates

Four- and 13-GHz tuned amplifiers have been implemented in a partially scaled 0.1-1 μm CMOS technology on bulk, silicon-on-insulator (SOI), and silicon-on-sapphire (SOS) substrates. The 4-GHz bulk, SOI, and SOS amplifiers exhibit forward gains of 14, 11, and 12.5 dB and F_min's of 4.5 (bulk) and 3.5 db (SOS). The 13-GHz SOS and SOI amplifiers exhibit gains of 15 and 5.3 dB and F_unn's of 4.9 and 7.8 dB. The 4-GHz bulk amplifier has the highest resonant frequency among reported bulk CMOS amplifiers, while the 13-GHz SOS and SOI amplifiers are the first in a CMOS technology to have tuned frequencies greater than 10 GHz. These and other measurement results suggest that it may be possible to implement 20-GHz tuned amplifiers in a fully scaled 0.1-1 μm CMOS process     

A photoelastic study of an angle crack specimen subject to mixed mode I–III displacements

A methodology, incorporating the use of an automated polariscope together with three-dimensional photoelasticity, is described and employed to determine mode III stress intensity factors. A series of angled cracks in a modified compact tension specimen were examined. The cracks were at an angle to the face of the specimen so that mode I and III displacements were produced. The results of the experiments were compared with the standard expressions for K_I and K_III, and some recent modifications to the expressions. The results support the findings of recent finite element analyses and fracture work by others that the expressions are not accurate and that the stress intensity factors vary along the crack front.     

A monolithically integrated optical differential amplifier forapplications in smart pixel arrays

A cascadable, optical differential amplifier with an active output is realized in AlGaAs-GaAs by the monolithic integration of three devices: A photodiode (PD), a light-emitting diode (LED) and a combination of a photodiode and a junction field-effect transistor (PINFET). A minimum optical switching power of 15 pW, an optical gain of more than 10⁶, a contrast ratio greater than 1000 and an optical output power of 17 μW are obtained. For a contrast ratio of 10, a switching energy of 2 pJ is required, resulting in a unity gain bandwidth of 4.2 MHz     

Antiretroviral drugs as a public health intervention for pregnant HIV-infected women in rural South Africa: an issue of cost-effectiveness and capacity

OBJECTIVE: To estimate cost-effectiveness and capacity requirements for providing antiretroviral drugs to pregnant HIV-infected women in rural South Africa. SETTING: Hlabisa health district, where HIV prevalence among pregnant women was 26.0% in 1997. METHODS: Calculation of the number of paediatric HIV infections averted under three scenarios, and their cost. No intervention was compared with scenario A (zidovudine delivered within current infrastructure), scenario B (zidovudine delivered through enhanced infrastructure), and scenario C (short-course zidovudine plus lamivudine delivered through enhanced infrastructure). Cost-effectiveness was defined as cost per infection averted and cost per potential life-year gained. Capacity was determined in terms of staff and infrastructure required to effectively implement the scenarios. RESULTS: With no intervention, 657 paediatric HIV infections were projected for 1997. In scenario A this could be reduced by 15% at a cost of US$ 574 825, in scenario B by 42% at US$ 1520770, and in scenario C by 47% at US$ 764901. In scenario C, drugs accounted for 76% of costs, whereas additional staff accounted for 18%. Cost per infection averted was US$ 2492 and cost per potential life-year gained (discounted at 3%) was US$ 88. Cost of scenario C was equivalent to 14% of the 1997 district health budget. At least 12 extra counsellors and nurses and one laboratory technician, together with substantial logistical and managerial support, would be needed to deliver an effective intervention. CONCLUSION: Although antiretrovirals may be relatively cost-effective in this setting, the budget required is currently unaffordable. Developing the capacity required to deliver the intervention would pose both a major challenge, and an opportunity, to improve health services.     

Correlation and prediction of dense fluid transport coefficients. I. n-alkanes

Recent accurate measurements of the self-diffusion coefficient for n-hexadecane and n-octane and of the viscosity coefficient for n-heptane, n-nonane, and n-undecane over wide pressure ranges have been used to provide a critical test of a previously described method, based on consideration of hard-sphere theory, for the correlation of transport coefficient data. It is found that changes are required to the universal curve for the reduced viscosity coefficient as a function of reduced volume and, also, to the parameters R _D, R , and R which were introduced to account for effects of nonspherical molecular shape. The scheme now accounts most satisfactorily for the self-diffusion, viscosity, and thermal conductivity coefficient data for all n-alkanes from methane to hexadecane at densities greater than the critical density.     

Structural evolution in gel-derived mullite precursors

The evolution of mullite from organo-metal gel precursors above 700 °C is found to be strongly influenced in both gel pieces and powdered samples by the thermal pretreatment at lower temperatures. Under the present conditions, the optimum preheating temperature was found to be 350 °C, at which temperature an anomalously high concentration was found of an Al species with a characteristic ²⁷Al magic-angle spinning NMR resonance at about 30 ppm. Such Al sites are often described as pentaco-ordinated, but an alternative assignment is considered. The optimum temperature for the formation of this Al site is also optimal for the catalytic formation of aromatic molecules from the residual organic fragments and/or solvent present. Mass spectrometry shows that under the present reaction conditions, these aromatics are thermally stable up to at least 900 °C in air, and the prolonged presence of their decomposition products (CO and water) could facilitate the transformation of the gel to crystalline mullite. The ²⁹Si NMR spectra indicate at least three different Si environments, including one which may arise from the formation of silicon oxycarbide glasses in these gels.     

Sterol composition of the phytolaccaceae and closely related families

Total sterols were analyzed from 28 species of Phytolaccaceae and from 29 species of closely related families—Basellaceae, Portulaccaceae, Molluginaceae, and Stegnospermataceae. Eighteen of twenty-eight species of Phytolaccaceae contained dominant Δ⁷-sterols while six species had dominant Δ⁵-sterols. Three species had dominant Δ⁰-sterols. Sterol composition strongly reflected taxonomic position. Nineteen of twenty-nine species from Basellaceae, Portulaccaceae, Molluginaceae, and Stegnospermataceae contained dominant Δ⁷-sterols while ten species contained dominant Δ⁵-sterols. Until recently Δ⁷-sterols were considered rare in higher plants. It appears that a large number of species in the order Caryophyllales contain primarily Δ⁷-sterols.     

Aliphatic heterocyclic polymers

Aliphatic polybenzoxazoles, polybenzothiazoles, and polybenzimidazoles have been prepared by three methods: in poly(phosphoric acid), by the polyamide precursor, and by melt polymerization. The melt polymerization method was found to be the most satisfactory. All of the aliphatic heterocyclic polymers had excellent thermal stability, resistance to alkaline hydrolysis, high glass transition temperatures, and a high degree of flexibility. The only class of polymer found having any degree of solubility, however, was the polybenzimidazoles. Aliphatic polybenzimidazole films were prepared by solution casting. These films were found to be extremely flexible at ambient and cryogenic temperatures. The films were unaffected by alkaline hydrolysis, even in an oxidizing medium. A molding prepared from the aliphatic polybenzimidazole had excellent physical properties at both cryogenic and room temperature.