Increased dermal carotenoid levels assessed by noninvasive reflection spectrophotometry correlate with serum levels in women ingesting Betatene

beta-Carotene is being used as an oral sun protectant, and evidence indicates that carotenoids may protect human skin from light-induced lesions. However, limited information is available on the distribution and accumulation of beta-carotene in skin, especially with respect to various skin regions. With the use of reflection spectroscopy, we investigated the accumulation of total carotenoids in human skin after repeated supplementation of 12 women with beta-carotene from a natural source Betatene, an algal extract. After daily ingestion of 24 mg beta-carotene (in Betatene) for 12 wk, an increase in carotenoid skin levels was observed. Highest basal values were measured in skin of the forehead, palm of the hand and dorsal skin, with lower levels measured in skin of the arm and back of the hand. Upon treatment, increases in carotenoid skin levels were found in all areas as follows: 2.4-fold in forehead, 0.7-fold in dorsal skin, 2.2-fold in the palm of the hand, 17-fold on the back of the hand and 1.7-fold on the inside of the arm. After cessation of treatment, the carotenoid levels decreased in all skin areas. Serum beta-carotene levels were elevated upon treatment and correlated with carotenoid skin levels. Correlations for serum vs. skin from the palm of the hand (r = 0.94) and skin from the forehead (r = 0.89) were calculated, indicating that serum levels appeared to be a suitable indicator for carotenoid accumulation in specific regions of the skin. With doses of approximately 20-25 mg carotenoids/d, it is possible to raise dermal carotenoid levels.     

Kinetic studies of steam gasification of char in the presence of H2, CO2 and CO

Kinetic studies have been carried out to elucidate the mechanisms of steam and CO₂ gasification of char and the interactions of these gasifying agents. The positive and negative influences of all product gases, excluding methane, were considered. An empirical approach was derived to describe the effects of the degree of carbon conversion on the reaction rate as a function of relevant test parameters (pressure range 1–70 bar, temperature 800–1000 °C). To assess the validity of the derived kinetic equation a model of a fluidized-bed gasifier is presented.     

Thermosolutal convection during dendritic solidification of alloys: Part II. Nonlinear convection

A mathematical model of thermosolutal convection in directionally solidified dendritic alloys has been developed that includes a mushy zone underlying an all-liquid region. The model assumes a nonconvective initial state with planar and horizontal isotherms and isoconcentrates that move upward at a constant solidification velocity. The initial state is perturbed, nonlinear calculations are performed to model convection of the liquid when the system is unstable, and the results are compared with the predictions of a linear stability analysis. The mushy zone is modeled as a porous medium of variable porosity consistent with the volume fraction of, interdendritic liquid that satisfies the conservation equations for energy and solute concentrations. Results are presented for systems involving lead-tin alloys (Pb-10 wt pct Sn and Pb-20 wt pct Sn) and show significant differences with results of plane-front solidification. The calculations show that convection in the mushy zone is mainly driven by convection in the all-liquid region, and convection of the interdendritic liquid is only significant in the upper 20 pct of the mushy zone if it is significant at all. The calculated results also show that the systems are stable at reduced gravity levels of the order of 10⁻⁴ g ₀ (g ₀=980 cm·s⁻¹) or when the lateral dimensions of the container are small enough, for stable temperature gradients between 2.5≤G _l≤100 K·cm⁻¹ at solidification velocities of 2 to 8 cm·h⁻¹.     

Video-as-data: Technical and social aspects of a collaborative multimedia application

We studied the use of a collaborative multimedia system for coordinating teamwork among members of a neurosurgical team. We analyze the use of video within the operating room and the use of broadcast audio and video to other locations in the hospital to enable remote neurophysiological monitoring. We describe how the multimedia system was used in a real world work context, including its benefits and problems. We argue that video can be useful as more than just pictures of people talking to one another; video can be a rich tool to enable analysis and problem solving. We discuss privacy problems inherent in collaborative multimedia technology and describe how they played out in the hospital during the course of our study.     

High-frequency FET noise performance: a new approach

A formulation is proposed for calculating the FET noise performance in the high-frequency range (EHF). In the first step, the concept of a local small-signal equivalent circuit is introduced, and a novel method for calculating the FET admittance parameters is proposed. In the second step, a novel formulation of the impedance field is given. It is shown that this approach reflects better the frequency evolution of the noise source values and consequently gives a better noise figure     

Permeability for cross flow through columnar-dendritic alloys

Experiments for measuring permeability in columnar-dendritic microstructures have provided data only up to a volume fraction of liquid of 0.66. Hence, the permeability for flow perpendicular to the primary dendrite arms in columnar-dendritic microstructures was calculated, extending our data base for permeability to volume fractions of liquid as high as 0.98. Analyses of the dendritic microstructures were undertaken first by detecting the solid-liquid interfaces with a special computer program and then by generating a mesh for a finite-element fluid flow simulation. Using a Navier-Stokes solver, the velocity and pressure at the nodes were calculated at the microstructural level. In turn, the average pressure gradient was used to calculate the Darcy permeability. Permeabilities calculated by this versatile technique provided data at high volume fractions of liquid that merged with the empirical data at the lower volume fractions.     

Classifying biosignals with wavelet networks [a method fornoninvasive diagnosis]

In recent years, a particular challenge has arisen in noninvasive medical diagnostic procedures. Because biosignals recorded on the body surface reflect the internal behaviour and status of the organism or its parts, they are ideally suited to provide essential information of these organs to the clinician without any invasive measures. But how are the recorded time courses of the signals to be interpreted with regard to a diagnostic decision? What are the essential features and in what code is the information hidden in the signals? These questions are typical of so-called pattern-recognition tasks. This article reviews pattern recognition as it applies to medical diagnostics and discusses the concept of wavelet networks as a means of biosignal classification. An example is presented in which this approach was used for classifying preprocessed ECG signals to identify patients who were at high-risk of developing ventricular tachycardia (VT)