A flow-loop apparatus, incorporating a co-current double-pipe heat exchanger, was developed for investigating the deposition of solids from solutions of a multicomponent wax in a paraffinic solvent under turbulent flow. The deposition experiments were performed at Reynolds numbers of 10 000-31 000 with 7, 10, and 15 mass % wax-solvent mixtures at different hot and cold stream temperatures. In all experiments, the deposit was formed rapidly such that a thermal steady state was attained within 20-30 min. The deposit mass decreased with an increase in the Reynolds number, the wax-solvent mixture temperature, and the coolant temperature. The data were analyzed with a steady-state heat-transfer model, which confirmed the deposit mass to depend upon the relative magnitudes of the thermal resistances in series as well as the fractional temperature drop across the deposit layer. The estimated liquid-deposit interface temperature was shown to be close to the wax appearance temperature of each wax-solvent mixture. The average thermal conductivity of the deposit was estimated to be 0.35 W m -1 K -1 . The gas chromatograph analysis of deposit samples showed their wax content and carbon-number distribution to vary with the deposition time and Reynolds number. Overall, the results of this study confirm that the deposition process from "waxy" mixtures is primarily thermally driven under both laminar and turbulent flow.

A recent meta-analysis of 16 publications suggested that bone mineral density (BMD) is not associated with vitamin D receptor (VDR) gene polymorphism (VDRGP) at the 0.05 significance level when a study with genotyping mistakes is excluded. We wished to determine whether 'positive' findings supporting the BMD-VDRGP association may be explained by chance, and what factors affect the outcomes of these studies. Seventy-five articles and abstracts on the association of VDRGP with BMD and related skeletal phenotypes published before January 1997 were identified. Twenty-three of 67 (34.3%) studies on spinal BMD and 22 of 51 (43.1%) on femoral neck BMD had found a BMD-VDRGP association at p < 0.05, significantly (p = 7 x 10(-14) for spinal BMD, p = 9 x 10(-16) for hip BMD) higher than the expected 5% false positive rate under the null hypothesis of 'no association'. 'Positive' results were more frequently observed in studies on females before the menopause than those on females after the menopause (p < 0.02) or on male and female subjects combined (p < 0.05) when skeletal phenotypes at any bone sites were considered. The 'positive rate' among studies was also influenced by the age range of subjects studied and by the inclusion of subjects with osteoporosis. It is concluded that: (1) BMD is associated with VDRGP with high levels of confidence and (2) non-genetic factors and genetic heterogeneity interfere with the detection of the effects of VDRGP on bone phenotypes.

In a 1998 review article, Laurell andcolleagues performed a meta-analysis of relevant guided tissue regeneration (GTR) articles over the previous 20 years (1). The purpose of the present research was to expand on that work, particularly searching for trends discriminating between bioabsorbable and nonbioabsorbable barriers, as well as the use of enamel matrix derivative, with respect to interproximal bony defects. The most recent periodontal journals were reviewed and a search of PubMed (National Institutes of Health) was conducted via the internet covering 1990 to the present. Forty-nine articles were found to be relevant and within established parameters. The data were analyzed using (a) a variation of the methods described in Laurell et al.

We use techniques from fuzzy mathematics to develop metrics for measuring how well deaf and hard of hearing preschool students of Omaha Hearing School are closing the gap with respect to language growth.