Limitations on the uses of multimedia exposure measurements for multipathway exposure assessment--Part II: Effects of missing data and imprecision.

Multimedia data from two probability-based exposure studies were investigated in terms of how missing data and measurement-error imprecision affected estimation of population parameters and associations. Missing data resulted mainly from individuals'refusing to participate in certain measurement activities, rather than from field or laboratory problems; it suggests that future studies should focus on methods for maximizing participation rates. Measurement error variances computed from duplicate-sample data were small relative to the inherent variation in the populations; consequently, adjustments in nonparametric percentile estimates to account for measurement imprecision were small. Methods of adjustment based on lognormality assumptions, however, appeared to perform poorly.     

The integrated academic information management system at Columbia-Presbyterian Medical Center.

Over the past seven years, Columbia-Presbyterian Medical Center has been planning and implementing an integrated academic information management system. Accomplishments to date include establishing an institutional information architecture, installing a campus-wide network of workstations, recruiting the staff needed to develop and implement the system, and developing various applications. This paper presents the rationale and steps involved in these accomplishments, as well as data on use of the system so far.     

Spectral characterisation and frame synchronisation of optical fibre digital PPM

The discrete time decoding of data in pulse position modulation calls for accurate timing synchronisation, particularly at the frame rate. The spectral properties of optical fibre digital PPM are considered. An original expression is presented for predicting the spectrum and it is shown that, unlike satellite PPM, a component exists at the frame rate which may be used for timing extraction purposes. Further, it is illustrated that the modulation index can be used to enhance this component by up to 19 dB. This has been verified practically, with the results agreeing to within 1 dB of those predicted from the original expression presented.<>     

MAGNESIUM HYDROXIDE FILLED EVA: THE EFFECTS OF FILLER SURFACE MODIFICATION ON THE STRENGTH OF FILLER/MATRIX ADHESION AND THE CONSEQUENCES FOR COMPOSITE STRUCTURE AND PROPERTIES

The interaction of ammonium stearate (AS) and γ-aminopropyltriethoxysilane (APS) treatments with a magnesium hydroxide flame retardant filler and their effects on its use in an ethylene vinyl acetate copolymer compound have been investigated. The work has shown clear evidence of changes in the structure of the surface layers formed on the filler as the amount of additive is increased and the levels at which these occur can be correlated with theoretical monolayer quantities. Infrared (IR) spectroscopy data suggest that the stearate coating changes from a half salt to a full salt as the coating level is increased and that the APS coating on the filler initially has a significant bicarbonate content, presumably due to reaction with atmospheric carbon dioxide. The effect of coating level on the melt flow rate, insoluble matrix content, crystallisation behaviour, tensile properties, limiting oxygen index, and ageing of the filled compound has been studied. Distinct trends have been observed, many of which can be correlated with the structure of the filler surface layers. Of particular importance is the observation that, unlike APS, excess stearate appears to promote detrimental ageing effects.     

The determination of polymer additive effects in a spherilene process HDPE matrix upon water carry-over in water quenched,cast film extrusion

A test method useful in determining the effects of polymer additives upon water carry-over (WCO) in water quenched, cast film extrusion is presented. Data from this test is obtained on film specimens based in a Spherilene process HDPE resin individually doped with 250 and 500 ppm of six various primary and secondary antioxidants and acid scavengers. Water contact angles and film surface tension data is also presented. The WCO test is reproducible and data may be applied to commercial production. Different additives that carry out the same function in the polymer may have greatly varying WCO properties; these differences are not detected by equilibrium goniometry.     

A combinatorial phage display library for the generation of specific Fab fragments recognizing human spermatozoa and inhibiting fertilizing capacity in vitro

To select a source of lymphocytes for the generation of an anti-sperm-biased combinatorial phage display library, venous blood was obtained from 34 vasovasostomy (vasectomy reversal) patients approximately 3 mo after surgery. Using a variety of immunoassays, serum was analyzed for antibodies against human spermatozoa, and a patient was selected on the basis of high titer of antibodies that recognized the equatorial region of the sperm head and inhibited sperm fertilizing capacity in vitro. Total RNA isolated from the stored lymphocytes of this individual was reversed transcribed, and gamma1 (Fd) region and kappa chains were amplified by polymerase chain reaction for the successful construction of an antibody phage display library. The library was panned against human spermatozoa to isolate sperm-specific phage that recognized the equatorial region of the sperm head. Three preparations of Fab were tested via the hamster egg penetration test. Each preparation significantly (p < 0. 005) inhibited sperm-egg binding and fusion, with one preparation (designated Fab-G) causing complete inhibition. Sequence analysis of the kappa light gene encoding Fab-G revealed a 93% homology with the light chain of human anti-human immunodeficiency virus gp120 p35 variable region. This technology may have a practical application in characterization of the immune response to spermatozoa and for the design of sperm-based contraceptive vaccines.     

RP-HPLC binding domains of proteins

Procedures have been developed to identify the chromatographic binding domains of horse heart cytochrome c (Cyt c) and bovine growth hormone (bGH) during their interaction with reversed-phase sorbent materials. The procedure involves adsorption of the protein solute to the chromatographic sorbent, followed by proteolytic cleavage. Comparison of the proteolytic map obtained for Cyt c and bGH in free solution with the corresponding map obtained when these proteins are adsorbed to the chromatographic sorbent revealed significant differences in the digestion pattern. Following characterization of the peptides generated in both maps, the results indicated that specific regions on the surface of both Cyt c and bGH are inaccessible to tryptic cleavage when adsorbed to the hydrophobic surface of both a C-4 and a C-18 sorbent. Based on the assumption that the region of the protein surface that is in contact with the sorbent remains intact and bound to the sorbent during the digestion step, while the protein surface that is exposed to the solvent is accessible to proteolysis, the regions that were inaccessible to tryptic digestion were found to correspond to hydrophobic domains on the protein surface. These results also suggest that the three-dimensional structures of these proteins remain largely intact upon adsorption to the hydrophobic surface.     

Assessing terrestrial wildlife populations in the Toronto and Region Area of Concern

Beneficial use impairments (BUIs) under the Great Lakes Water Quality Agreement identify environmental issues requiring remedial action within the Great Lakes Areas of Concern (AOCs). We conducted this study to support the assessment of the wildlife component of BUI 3: degradation of fish and wildlife populations. We compared bird and amphibian (frogs and toads) data from the Toronto and Region Conservation Authority’s Terrestrial Long-term Monitoring Program in the Toronto and Region AOC to an adjacent, but otherwise similar, reference watershed, Duffins Creek. Twelve of 13 targets were met within the AOC for forest bird, wetland bird, meadow bird and amphibian populations based on averages of mean annual values at sites within the AOC that were within two standard deviations of averages at sites in the Duffins Creek reference watershed between 2008 and 2017. Even though wildlife populations within the AOC were within the normal range of variability expected from a reference watershed, they were often at lower levels than within the Duffins Creek reference watershed. In addition, forest bird and amphibian populations were negatively affected by urbanization within the AOC and meadow bird indices declined. We conclude that while wildlife populations within the AOC currently meet targets for BUI 3, they continue to be negatively impacted by numerous stressors that are primarily related to past and ongoing urbanization. Thus, continued restoration of wildlife habitat and protection of existing habitat within the AOC is highly recommended.     

Experimental and computational study of gas–solid fluidized bed hydrodynamics

The hydrodynamics of a two-dimensional gas–solid fluidized bed reactor were studied experimentally and computationally. Computational fluid dynamics (CFD) simulation results from a commercial CFD software package, Fluent, were compared to those obtained by experiments conducted in a fluidized bed containing spherical glass beads of 250– in diameter. A multifluid Eulerian model incorporating the kinetic theory for solid particles was applied in order to simulate the gas–solid flow. Momentum exchange coefficients were calculated using the Syamlal–O’Brien, Gidaspow, and Wen–Yu drag functions. The solid-phase kinetic energy fluctuation was characterized by varying the restitution coefficient values from 0.9 to 0.99. The modeling predictions compared reasonably well with experimental bed expansion ratio measurements and qualitative gas–solid flow patterns. Pressure drops predicted by the simulations were in relatively close agreement with experimental measurements at superficial gas velocities higher than the minimum fluidization velocity, U_mf. Furthermore, the predicted instantaneous and time-average local voidage profiles showed similarities with the experimental results. Further experimental and modeling efforts are required in a comparable time and space resolutions for the validation of CFD models for fluidized bed reactors.