Structure of intracellular mature vaccinia virus observed by cryoelectron microscopy

Intracellular mature vaccinia virus, also called intracellular naked virus, and its core envelope have been observed in their native, unfixed, unstained, hydrated states by cryoelectron microscopy of vitrified samples. The virion appears as a smooth rounded rectangle of ca. 350 by 270 nm. The core seems homogeneous and is surrounded by a 30-nm-thick surface domain delimited by membranes. We show that surface tubules and most likely also the characteristic dumbbell-shaped core with the lateral bodies which are generally observed in negatively stained or conventionally embedded samples are preparation artifacts.     

Regulatory roles of cyclin dependent kinase phosphorylation in cell cycle control

Cyclins and cyclin-dependent kinases (Cdks) are universal regulators of cell cycle progression in eukaryotic cells. Cdk activity is controlled by phosphorylation at three conserved sites, and many of the enzymes that act on these sites have now been identified. Although the biochemistry of Cdk phosphorylation is relatively well understood, the regulatory roles of such phosphorylation are, in many cases, obscure. Recent studies have uncovered new and unexpected potential roles, and prompted re-examination of previously assumed roles, of Cdk phosphorylation.     

Thermodynamic optimization of internal structure in a fuel cell

This paper shows that the internal structure (relative sizes, spacings) of a fuel cell can be optimized so that performance is maximized at the global level. The optimization of flow geometry begins at the smallest (elemental) level, where the fuel cell is modelled as a unidirectional flow system. The polarization curve, power and efficiency are obtained as functions of temperature, pressure, geometry and operating parameters. Although the model is illustrated for an alkaline fuel cell, it may be applied to other fuel cell types by changing the reaction equations and accounting for the appropriate energy interactions. The optimization of the internal structure is subjected to fixed total volume. There are four degrees of freedom in the optimization, which account for the relative thicknesses of the two (anode and cathode) diffusion layers, two reaction layers and the space occupied by the electrolyte solution. The available volume is distributed optimally through the system so that the total power is maximized. Numerical results show that the optima are sharp, and must be identified accurately. Temperature and pressure gradients play important roles, especially as the fuel and oxidant flow paths increase. The optimized internal structure is reported in dimensionless form. Directions for future improvements in flow architecture (constructal design) are discussed. Copyright © 2004 John Wiley & Sons, Ltd.     

Toward an integration of macro and micro measurement systems for the researcher and the clinician.

Comments on previous discussions (e.g., H. D. Grotevant; see record 1990-12120-001) on the development of strategies for developing key constructs of family functioning at both the macro and micro levels. The most generalizable models of family process should include data from both insiders and outsiders who make ratings at both the macro and micro levels. This position is based on the assumption that each measurement strategy and reporting agent brings with it a certain reliable bias or error that detracts from the core construct being examined. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Magnetic resonance imaging studies of the polymerisation of methylmethacrylate

Magnetic resonance imaging has been used to spatially map the time course of the bulk polymerisation of methylmethacrylate. Both two-dimensional projection and slice-selective techniques have been employed. Image intensities give qualitative information about viscosity, reaction rates and the localised extent of polymerisation. The importance of proton relaxation measurements in drawing quantitative conclusions is stressed.     

Stages of readiness to quit smoking: Population prevalence and correlates.

Examined the population prevalence and correlates of stages in smokers' readiness to quit, using data from 1,048 smokers recruited in a self-weighting, multistage, systematic clustered area sample. Smokers in the precontemplation stage (PCTS) comprised 24.1% of the sample, smokers in the contemplation stage (CTS) comprised 47.2%, and smokers in the preparation stage (PS) comprised 28.7%. The 5 significant independent predictors of being in the PCTS (vs the CTS) were (1) having a higher confidence of quitting, (2) seeing fewer health risks associated with smoking, (3) not having made an attempt to quit, (4) seeing quitting as more difficult, and (5) smoking 25 or more cigarettes a day. The 2 significant independent predictors of being in the CTS (vs the PS) were (1) having lower confidence of quitting and (2) not having tried to quit. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Color removal from dye wastewaters by adsorption using powdered activated carbon: Mass transfer studies

Color removal from synthetic dye wastewater which typically emanates from the Taiwan textile industry has been studied using powdered activated carbon (PAC) as an adsorbent. The CIE colorimetric system has been used in the measurement of color for the treatment of disperse-red-60 dye wastewater. The effect of contact time, dye concentrations and PAC dosage on color and color removal has been investigated. A film-pore double resistance diffusion model for mass transfer has also been used in this study to determine the effective diffusivity, D_eff, for the adsorption of disperse-red-60 dye wastewater to PAC.