An Electrooptical Sensor for Cardiac Sound and Vibrations

An electrooptical sensor for long-term recording of the apex cardiogram in a clinical environment is reported here. The active elements of the sensor include three red light-emitting diodes (LED's) and eight phototransistors. These function by detecting the change in light reflection from the chest wall caused by the mechanical vibrations and motions of the heart. The advantages of this sensor over the existing microphone include wide bandwidth (3.1 Hz-9.0 kHz), small physical size, and ease of attachment to patients in all positions.     

A Framework For Probabilistic Vehicle Routing

The stochastic vehicle routing problem is a problem of considerable current importance in operations research and industrial engineering. The basic problem is to determine a fixed set of vehicle routes of minimal expected total distance. All vehicles must leave from and eventually return to a central depot, and capacity constraints and probabilistic customer demands must be satisfied. In previous work, we assumed that the demand at each node i could be modeled by a Poisson distribution with mean Λi and that demands at nodes are mutually independent. We then developed an efficient heuristic solution procedure which was quite effective in generating an excellent set of fixed vehicle routes, as evidenced by extensive computational results. With this previous work as a starting point, in this paper we investigate solution procedures for the case where other appropriate probability distributions are assumed. In addition, we present analytical results describing the various relationships between design parameters and provide a framework for performing perturbation analysis. Finally, we focus on a more flexible model in which demands are correlated.     

Predicting drug dissolution profiles with an ensemble of boosted neural networks: a time series approach

Applicability of an ensemble of Elman networks with boosting to drug dissolution profile predictions is investigated. Modifications of AdaBoost that enables its use in regression tasks are explained. Two real data sets comprising in vitro dissolution profiles of matrix-controlled-release theophylline pellets are employed to assess the effectiveness of the proposed system. Statistical evaluation and comparison of the results are performed. This work positively demonstrates the potentials of the proposed system for predicting desired drug dissolution characteristics in pharmaceutical product formulation tasks.     

Two-dimensional transferred-echo double resonance study of molecular motion in a fluorinated polycarbonate

A case-control study was undertaken to provide information about the role of some husbandry practices and farm characteristics in the epidemiology of bovine tuberculosis in the Veneto Region. Twenty-seven breeding herds where a positive result to the single intradermal cervical tuberculin test was confirmed by post-mortem examination were compared with seventy-four herds which had been free of the disease for at least three years. Epidemiological information was collected on farms. The factors taken into account in the study were chosen on the basis of their epidemiological plausibility and of the local livestock characteristics. Multiple logistic regression was applied to analyse the data. Factors identified as possibly involved in increasing the risk of bovine tuberculosis in the Veneto Region were the presence of mixed (dairy and beef) enterprises (OR = 4.9, P = 0.001) and of cattle purchase (OR = 5.8; P = 0.003). Other factors (such as herd size, housing system, summer mountain pasture, possible contact with wild animals, and indirect contacts with other herds) did not appear to significantly contribute to tuberculosis presence in this area. The results of this case-control study support the hypothesis that in the Veneto Region bovine tuberculosis infection is still associated with classical risk factors both (directly or indirectly) related to cattle movements.     

Determination of the symmetry of the pair function in YBa2Cu3O7

We have determined that there is no measurable suppression ofT _c at a lead-YBa₂Cu₃O₇ junction below that of lead alone and present a qualitative argument that this implies singlet,s-wave pairing in YBa₂Cu₃O₇.     

The preparation and morphology of PPO–epoxy blends

Poly(phenylene oxide) (PPO) was found to be miscible in diglycidyl ether of bisphenol A (DGEBA) based epoxy. The PPO–DGEBA system exhibited upper critical solution temperature (UCST) behavior. The cloud point temperatures were measured and found to be sensitive to the mol wt of the epoxy resin. A series of PPO-modified epoxies were cured with piperidine at 160°C, which is above the cloud point temperature. Upon cure, two phase solids were formed, which contained discrete PPO particles. However, the two-phase particulate morphology was not uniform and numerous large, occluded PPO particles were observed. In order to improve the uniformity, several styrene-maleic anhydride copolymers were evaluated as potential surfactants for PPO-DGEBA bends. The formation of a uniform, particulate morphology was facilitated by the addition of a styrene–maleic anhydride copolymer, containing a 10:1 ratio of styrene to maleic anhydride. To our knowledge, this is the first time that an emulsifying agent has been added to improve the morphology of thermoplastic modified epoxies. © 1993 John Wiley & Sons, Inc.     

VISCOSITY STUDIES OF SYSTEM CaO-MgO-Al2O3-SiO2: II,CaO-Al2O3-SiO2*

Viscosity data are presented covering those compositions in the CaO-Al₂O₃-SiO₂ system which are liquid at 1500°C. The pattern of isokoms on the CaO-Al₂O₃-SiO₂ face of the compositional tetrahedron which represents the CaO-MgO-Al₂O₃-SiO₂ system is a system of lines which roughly parallel the lines along which the lime content is constant. There are, however, considerable deviations from this parallelism in regions of very low and very high alumina content.