ALBERT

Notes: Abstract The Stevenson Technology Innovation Act of 1980 has passed Congress and has been signed by the President. The legislation accomplishes two main functions. The first part establishes an Office of Industrial Technology in the Department of Commerce which will oversee the establishment of a wide variety of university-affiliated centers. The Centers will: 1) Perform research supportive of technological and industrial innovation including cooperative industry-university basic and applied research; 2) provide assistance to individuals and small businesses in the generation, evaluation and development of technological ideas supportive of industrial innovation and new business ventures; 3) provide technical assistance and advisory services to industry, particularly small businesses; and 4) provide curriculum development, training, and instruction in invention, entrepreneurship, and industrial innovation. The second part of the Act is concerned with the utilization of Federal Technology. Some of the provisions are: 1) Each Federal Laboratory shall establish an Office of Research and Technology Applications; 2) each Federal laboratory having a total annual budget exceeding $20,000,000 shall provide at least one professional individual full-time as staff for its Office of Research and Technology Application; and 3) after September 30, 1981 each Federal agency shall make available not less than 0.5 percent of the agency's research and development budget to support the technology transfer function of the Office of Research and Technology Applications. The legislation also establishes a Center for the Utilization of Federal Technology in the Department of Commerce to serve as a central clearinghouse for the collection, dissemination, and transfer of information on Federally owned or originated technology having potential application to State and local government and to private industry.

Notes: Abstract In this article we present a detailed description of an analog-digital computer model of those aspects of the bone which are considered to be important in the short-term homeostasis of calcium ions in the body. Quantitative relationships for parameters and variables were obtained from the literature either directly or indirectly. The bone-calcium model was linked to a previously described model of the entire homeostatic system for calcium ions. Simulated experiments, using the entire model showed close correspondence with animal experiments described in the literature, thus validating the model for those cases. The simulated experiments included those concerned with (1) the effects of calcium infusion and calcium removal, (2) parathyroid hormone and calcitonin injection, and (3) removal of the parathyroid glands. The model can be expanded to include further quantitative relationships and details related to specific species, as this information becomes available. We hope that in the meanwhile the model will promote understanding of the general principles of the bone in calcium homeostasis.

Notes: Abstract An a.c. electrophoretic technique in the frequency range between 2–10 Hz, using a rectangular chamber design, has been developed for measuring the surface electric charge density of human red blood cells. With the a.c. approach, mobility can be determined rapidly, electrode polarization is minimized and the construction of the chamber simplified. For frequencies under 10 Hz and a chamber thickness of 150 μm, a theoretical analysis of the electroosmotic flow profile shows that it is almost identical to the d.c. case. With the a.c. method and using a 0.145 N NaCl solution buffered with NaHCO3, the mobility of red cells measured at the lower stationary level is found to be −1.07±0.02 (S.D.) μmsec−1 V−1 cm. The zeta potential and charge density calculated from the mobility are −14.03±0.26 (S.D.) mV and −3603±69 (S.D.) esu cm−2, respectively.

Notes: Abstract Multiaxis robotic and prosthetic systems have a number of common characteristics such that control techniques for robots may sometimes be adapted for prosthetic devices. One characteristic that is particularly important for these systems is that good performance over a wide range of motion and loads is difficult since it is dependent upon complex time-varying, nonlinear dynamics. This paper gives an example of the complexity of the dynamics for a two degree-of-freedom, double-inverted pendulum which has been used as a model for study of biped locomotion. Two different methods called the “inverse plant” and State Space Memory, now being considered for robotic mechanisms, are then presented which base the control on the dynamics of the system and may have application for prosthetic devices.

Notes: Abstract The past ten years have witnessed the introduction of several new methods for chronic recording of electrical activity in peripheral nerves, single nerve fibers and muscles, and for monitoring mechanical events correlated with muscular action. Although these methods were developed as research tools in the study of movements of unrestrained, intact animals, such implantable interfaces with nerve and muscle also promise to be of value in clinical applications; some novel clinical efforts are already being pursued. A review is given of various new techniques that may be clinically applicable and the issues of surgical constraints, quality of signal isolation, and long-term reliability of implantable devices, which ultimately determine the usefulness of each method, are discussed. Experimental devices reviewed include nerve cuff electrodes, floating single-unit electrodes, EMG electrodes, length gauges, and force gauges. General considerations for potential clinical applications are then given.

Notes: Abstract The development of physical or mathematical models offers potentially powerful instruments for understanding interactive mechanics of the circulatory system. Coupled with computer technology, the resultant scientific armamentarium held promise of rapid solutions to complex problems. Expectations have not been fulfilled for several reasons, which are discussed. Lack of information, necessary to achieve realistic model responses, often constrains their applicability. Since complete information, required for all components, may not be available, the importance of representing specific task-significant components is explored. The successful use of this approach is illustrated.

Notes: Abstract In the Cardiac Surgical Intensive Care Unit (CICU) of the University of Alabama Hospital in Birmingham, Alabama, the mean arterial pressure (MAP) is regulated by computer (H-P 21 MX) controlled infusion of vasodilating agents and has been performed in 1100 hypertensive patients following open heart surgery. The MAP controller was developed based on investigation of the dynamics of the physiological responses of hypertensive patients to trimethaphan camsylate (Arfonad) and sodium nitroprusside (Nipride). Representative responses were selected for investigation by digital simulation of a computer programmed version of a proportional-integral-derivative (PID) controller algorithm. The PID controller parameters were tuned to elicit a response with acceptable settling time and minimal overshoot during the time course of the simulated MAP. Eight IMED 929 (IMED Corporation, San Diego, CA) digitally controlled infusion pumps interfaced with our computer based CICU system are used to regulate the blood pressure of patients following cardiac surgery. A microprocessor based blood pressure controller employing this algorithm has been developed and is being evaluated. For system design, analysis, and evaluation, the essential aspects of the arterial blood pressure (MAP) and its response to nitroprusside has been modeled. The arterial pressure is considered the sum of nonstationary stochastic background activity and a change due to the nitroprusside (characterized by a transfer function). The model was applied to the simulation of a clinically used controller and has provided insight into responses observed in the treatment of patients. The model is presently being used for computer-aided design and evaluation of an adaptive controller.

Notes: Abstract Pressure recorded from inside the cranium (intracranial pressure) is a complex function of the interaction of three compartments, each under its own physiologic control. Physiologic or pathologic changes in one compartment affect the other two compartments. The three compartments are vascular, cerebrospinal fluid, and extracellular fluid. Adaptive mechanisms are most rapid relative to the vascular compartment and slowest relative to the extracellular fluid compartments. Systems for closed-loop control of intracranial pressure could conceivably be used to manipulate any of the three compartments by measuring the variables involved in its control and manipulating them. The vascular component could be regulated by the controlled infusion of vasoactive drugs and the measurement of their effect. The extracellular space could be modified by determining its osmolality and modifying it using either dehydrating agents or direct electrical stimulation of the hypothalamic control centers for fluid and electrolyte balance. The cerebrospinal fluid compartment is at present the most easily manipulated of the three compartments. The pathologic condition where cerebrospinal fluid production is greater than absorption is hydrocephalus. In this condition, closed-loop control of intracranial pressure may be critical to prevent the conversion of a transient pathologic state into a permanent one in which a shunting device is always required. Overdrainage of the cerebrospinal fluid compartment can cause ventricular coaptation and lead to inability to control the hydrocephalus. Present systems for hydrocephalus control are valve regulated with a preset opening pressure and, occasionally, an interposed device to prevent siphoning. Feedback-loop control of intracranial pressure could, by varying flow or resistance, allow pin-point control of intracranial pressure and prevent the complications of prolonged shunting.

Notes: Abstract Many of the long-term complications seen in insulin-dependent diabetic patients are not averted by conventional modes of insulin therapy. A commonly expressed hypothesis is that more intensive efforts directed at improved metabolic control in diabetic subjects may result in a decrease of long-term complications. Therefore, increasing attention is being devoted to development of strategies designed to achieve improved blood glucose and metabolic control in insulin-dependent diabetic subjects. The approaches can be divided into three categories: [1] Transplantation, [2] Mechanical devices, and [3] Intensive, conventional therapy. The development of the transplantation approach requires resolution of the problem of rejection and the need for immunosuppression. Recent studies indicate that islet transplantation may be performed without long-term immunosuppression. Closed-loop devices for use at the bedside are available at the present time for short-term investigational use. A device for long-term portable use is not available because of the lack of an adequate glucose sensor. Open-loop devices are currently available that enable long-term clinical studies in humans. Some patients have used these devices at Washington University for over two years. In a few, there has been reversal of some of the neuropathy with retinal vascular leakage and near normal, long-term metabolic control. Some findings in over twenty patients studied long-term include the following: 1. Reduction of postprandial hyperglycemia is possible with intravenous. subcutaneous, or intraperitoneal insulin delivery; 2. Hypoglycemia remains the most common problem seen in ambulatory patients treated with open-loop pumps and necessitates glucose monitoring by the patient at home; 3. Long term “normalization” of plasma glucose is not achieved with openloop systems; 4. Maturity onset diabetic patients are easier to control than juvenile onset diabetics; 5. Some patients tolerate hypoglycemia better than others and this may determine who does well long-term; 6. Long-term subcutaneous insulin delivery is safe, whereas other forms of insulin delivery carry a greater risk; 7. Peripheral hyperinsulinemia is frequently found in patients treated by open-loop methods and may have long-term detrimental effects; 8. Behavioral and psychosocial variables may influence long-term results and have not been studied in detail; 9. The primary clinical use of open-loop systems in diabetic patients at the present time is their use in pregnancy and in patients unresponsive to conventional therapy. Our interest in these devices is to determine if they can avert or reverse the long-term complications of the diabetic. We do not consider them safe for routine use in clinical practice and are concerned that practitioners inexperienced in their use may employ these devices prematurely, before their safety and effectiveness are demonstrated in carefully controlled clinical studies.

Notes: Abstract The application of operations research/management science in the developing country has met with uneven success. Social, cultural, and political factors have constrained direct application of OR technology from industrialized countries to developing countries. Review of OR experience in the United States, especially pitfalls and successes of OR application, does provide significant information which can benefit the application of operations research in the developing country. Successful application of operations research is apt to be highly beneficial if operations researchers in the developing country can effectively deal with the challenges of cultural constraints, an uncertain decision environment, human resource management, and a bounded rationality unique to each developing country.

Notes: Abstract Statement of Problem To develop and test the usefulness of the TECTRA Newsletter, a mechanism for disseminating information about technology transfer and the TECTRA data base. Current literature was used to show the emerging importance of technology transfer and the Newsletter's role in this area. Sources of Data Primary data was collected from the recipients of the Newsletter. This included technology transfer agents, administrators of various municipal government departments, and some executives in private enterprise. Conclusions Reached It was shown that the TECTRA Newsletter created interest in the cases reported by the Newsletter, as well as awareness of the TECTRA data base. It was also shown that the Newsletter is regarded as a useful tool by readers, and should therefore be viewed as an on-going project.

Notes: Abstract A brief account of the growth of the “market” concept, as related to technology transfer, leads into the establishment of Dr. Dvorkovitz & Associates by its founder and owner, Vladimir Dvorkovitz, Ph.D., where the company has been, where it is at present, and plans for the immediate future, as related to the world wide dissemination of data on technology available for license from industry, government organizations, university and private research centers, and individual inventors. Company activities cover the computerized data bank, InstanTechEx; TechEx, the annual World Fair for Technology Exchange; the publication on licensing and technology transfer, UNIT.

Notes: Abstract This paper considers the problems of the evaluation of the benefits that may be derived from technology transfer. When intangeable benefits are considered the evaluation process becomes more costly and often less reliable. A model is developed that should assist in the evaluation of externalities and other intangeable benefits.

Notes: Abstract Among the problems facing decision makers are those of receiving reliable warnings of nascent crises and of having relevant information which can be brought to bear on unforseen decision problems. This paper describes how computer technology is being used to address both of these problems in a real-time environment. Specifically, computers are being used to manage and analyze the relations among nations in order to forewarn decision makers withad hoc information retrieval and data analysis capabilities. Using computers in this fashion in the foreign policy arena is a recent innovation which may have application in other arenas where decision makers must continually anticipate and adapt to unfolding world situations.

Notes: Abstract An analogy between the flow of technology and the flow of electricity is used as a method to analyze technology transfer. This effort is expanded by an analogy to the Lewin's field theory in Social Science. An effort is then made to understand better the types of barriers to technology transfer. Several classes of barriers are identified and are then discussed in detail.

Notes: Abstract The general objective of this paper is to propose the establishment of a federal cost-sharing policy for reducing risk in transferring technology from the R&D stage to commercialization. Minimization of this risk barrier is expected to encourage diverse groups to participate in technology transfer. Section II focuses on specific barriers that impede technology transfer efforts and it presents policy options to minimize identified barriers. Section III introduces objectives of cost-sharing experiments from which cost-sharing policies can be formulated. In addition, we also identify specific cost-sharing participation criteria and success variables for the policy.

Notes: Abstract A technology delivery system designed to provide small and medium-sized businesses with improved access to technological resources for enhancing their productivity and competitiveness has been tested under controlled conditions in the southeastern United States. The demonstration project involved federal research laboratories, state universities, National Information Service and Economic Development Administration of the U.S. Department of Commerce, and technology users in the private sector. The results of the 18 month project are reported and assessed to identify the conditions for the establishment of a national technology network for small and medium sized firms.

Notes: Abstract Promoting industry-wide innovation is a particularly difficult problem of technology transfer because of issues of proprietary information and competition. A promising approach to this problem is network-building through mission-oriented conferences that facilitate communication among those involved in the transfer of technology. This paper defines basic concepts of networking and views mission-oriented conferences as temporary systems. It describes how one mission-oriented conference, the Footwear Technology Symposium, was designed to promote networking. The paper also provides examples of other mission-oriented conferences (including a number of what have been called “research utilization conferences”). The article concludes with a set of recommendations for planners of mission-oriented conferences.

Notes: Abstract This paper is concerned with the impact of the Medical Device Amendments of 1976 and its implications in terms of innovation. With this objective the paper first describes the Medical Device Amendments of 1976. The paper then reports empirical evidence on the sources of a subset of innovations regulated by the Amendment's clinical chemistry diagnostic products. Finally, based on the pattern of innovations found, some thoughts are expressed about the likely effects of the Amendments.

Notes: Abstract Most efforts in transferring technology to a specific location are carried out following essentially a research approach. However, imposing the research approach onto a situation for which a specific solution needs to be created or restructured represents an inappropriate transfer of technology. A planning and design approach (PDA) is called for. “TOTALS” is based on planning and design concepts adapted to solving the problems of technology transfer. It is composed of six time-based and repeating phases, comprised of nineteen steps. It is based on four important concepts: a systems view of technology, a Technology Transfer Equation, five different purposeful perspectives regarding technology transfer activities, and a holistic PDA. No particular approach, technique, model or body of knowledge can be said to be predominant.

Notes: Abstract In this theoretical study of epileptiform activity, the onset of self-sustained activity in a system of interconnected cells is explored using (a) analytical models, and (b) computer simulations. An approximate analytical model demonstrates that the system can be either stable, with self-sustained activity impossible, or potentially unstable, with the possibility of going into self-sustained activity if the firing rate is driven beyond a critical level. The approximations made in this initial model led to substantial discrepancies when the analytical criticality condition was tested against computer simulations in relatively small networks of neurons. Therefore, using a refined analytical model, a numerically more accurate, although computationally cumbersome, criticality condition was derived which agrees well with the simulation results. Two simulation models are used: a deterministic simulation in which the average number of cells firing at each simulation step is calculated and a probabilistic simulation in which the stimulation and firing of each individual neuron is followed. Comparison between the behavior of the probabilistic and deterministic simulations near criticality demonstrates that random fluctuations can force the system toward either self-sustained activity or decay.

Notes: Abstract Conventional peripherally invasive mechanical circulatory assist methods such as intra-aortic balloon pumping are of only limited hemodynamic benefit in cases of severe left ventricular failure. This article deals with the analysis and testing of a new pumping concept (16), that is theoretically capable of providing adequate circulatory and respiratory assistance in cases of severe uni- or biventricular failure. This assist system combines an intra-aortic balloon pump (a series form of left ventricular assistance) and pulsatile venoarterial membrane oxygenator bypass (a parallel mode of assistance). The combined pulsatile assist system is controlled by a digital microprocessor which provides appropriate phasing relative to the R wave of the ECG. This support system requires only cannulation of femoral or other easily exposed vessels. Blood-gas exchange gas diffusion or massive pulmonary embolism or other perfusion defects. This concept has been tested in a series of experiments with canine models of ventricular failure. The results of this study indicate that (1) balloon pumping becomes much more effective when combined with pulsatile veno-arterial bypass in cases of severe ventricular failure with an attendant hypotensive circulatory state, and (2) the automatic control system is effective in optimizing the performance of the combined assist system.

Notes: Abstract A two-dimensional finite element model incorporating cancellous bone inhomogeneity is used to study femoral head stress alterations caused by changes from the usual articular contact patterns. The contact stress distributions, calculated from an earlier mathematical analysis by Greenwald and O'Connor (16), are found to influence not only the adjacent subchondral bone, but relatively distant parts of the head as well. Both abnormally large joint incongruity and abnormally low cartilage compliance cause load to shift away from the superior “weight-bearing” area, out toward the periphery of the contact region. As a consequence, transverse compressive stresses, which are of appreciable magnitude but which do not contribute to weight bearing, are built up throughout much of the superior and central portions of the femoral head. Most small changes in the overall cartilage thickness or in its thickness distribution, when considered in isolation from hip compliance changes, have only minor effects on the internal stress distribution. An important exception is cartilage thinning at the superior margin, which can result in abrupt longitudinal compressive stress concentrations. It is suggested that such alterations of the normal patterns of stress transmission may contribute to sclerosis or to the formation of osteophytes or cysts in the osteoarthritic hip.

Notes: Abstract Models of the pulmonary airway network were analyzed to determine the effect of reflections on apparent phase velocity measurements in the trachea of dogs. A stiffly constrained elastic tube filled with a viscous fluid was used to model each airway segment, and a series resistance-capacitance combination served as a terminal element for each pathway. Reflection, transmission and attenuation coefficients at each branching site and reflection coefficients at each termination were computed. Composite sinusoidal pressure waves at two sites in the trachea where computed for frequencies from 5 to 150 Hz, and crosscorrelograms were used to determine apparent phase velocities. In an asymmetrical model, the randomness of the airway diameters caused phase shifts in the reflection coefficients to vary between approximately 0° and 180° resulting in significant destructive interference between the reflected waves. Calculated apparent phase velocities agreed with the assumed values within 40% at frequencies of 70 Hz and below and within 20% at higher frequencies in this model.

Notes: Abstract The effect of respiratory controller gain on the speed of correction of disturbances in CO2 balance, and the energy used by the respiratory muscles during the correction period is explored using a mathematical model. As controller sensitivity is increased, CO2 balance is more rapidly restored, but there is a greater expenditure of energy in breathing. The relationship between speed of correction and energy expenditure rises to a maximum value near usual values for controller sensitivity to CO2 in normal human adults. With less efficient respiratory muscles or with higher resting levels of PCO2, maximum values for the ratio of speed to energy consumption occur at decreased levels of controller sensitivity. Increased cardiac output and functioning central and peripheral CO2 chemoreceptors improve speed of response without proportionate rises in energy use.

Notes: Abstract In mathematical simulation of oxygen transport the diffusion problem is often simplified by several assumptions including that of local chemical equilibrium and of negligible augmentation of oxygen transport by oxyhemoglobin diffusion. In the present work the applicability of the various assumptions is investigated by numerical solution of the equations governing transient diffusion and reaction in hemoglobin layers. The fluxes, and space and time scales are chosen to cover the range of interest in the microcirculation. The results show that significant improvements in accuracy are possible by treatment of a more complete system of equations, and show the relative importance of the various simplifying assumptions.

Notes: Abstract The adsorption of human fibrinogen (HFb) onto polyethylene at pH 7.4 and 37°C is irreversible with the saturated value 0.51 μg/cm2. The established dependence of the concentration of irreversibly adsorbed HFb on the concentration of HFb in solution does not reflect an equilibrium between adsorption and desorption and cannot be described by an adsorption isotherm. No reversible adsorption of HFb and HSA at 37°C has been observed. At lower temperatures, both reversibly and irreversibly adsorbed HFb have been detected.

Notes: Abstract Coiled wire electrodes have been evaluated for intramuscular electrical stimulation. Monophasic cathodal stimulation at average current densities not exceeding 10 μamp/mm2 (0.2 μC/mm2/stimulus pulse at 50 Hz) shows no increased tissue trauma over that incurred by passive implant. At average current densities greater than 50 μamp/mm2 (1.0 μC/mm2 /stimulus pulse at 50 Hz), extensive tissue damage occurs. The muscle tissue damage appears to be secondary to blood vessel damage. With balanced charge biphasic stimulation, greater charge densities could be used without the effect of increased tissue damage. However, to avoid electrode corrosion, the maximum charge injection during the cathodic phase should be less than 0.4 μC/mm2 at 50 Hz. Balanced charge biphasic stimulation is considered safer than monophasic stimulation, and is recommended for chronic use.

Notes: Abstract The control of artificial limbs and other restorative systems is discussed in terms of closed-loop control and sensory feedback. Feedback modalities are classified in three categories: (1) Supplemental Sensory Feedback (2) Artificial Reflexes (3) Control Interface Feedback. Historical attempts to provide sensory feedback in prostheses are discussed and put in the context of more modern efforts in this area.

Notes: Abstract Progress in development of elements of higher-generation cochlear implant devices is briefly summarized. Initial tests with early model devices indicate that these devices will gain wide application, as aids capable of effecting significant levels of speech recognition in the profoundly (totally) deaf.

Notes: Abstract Functional palmar prehension and release and lateral prehension and release were developed in C5 quadriplegic patients by electrical stimulation applied chronically to the forearm muscles. Percutaneous electrodes were used for stimulation. Graded contraction strength was achieved by both recruitment and temporal summation which the patient controlled voluntarily. generally, the position of either the head or the shoulder was sensed and used as the proportional control source, with on/off and automatic control functions provided by a myoelectric signal. Miniaturized electronic hardware has been developed and is the subject of ongoing clinical evaluation.

Notes: Abstract The development of tension and shortening in cardiac and skeletal muscle exhibits phenomena suggestive of control by feedback mechanisms at the molecular level. Two of these, presented here, may have surprising implications for the cross-bridge theory of muscular contraction. It can be argued, from the basis of the cross-bridge theory, that the extended muscle is unstable against further imposed stretch by reason of a corresponding decrease of generated tension. Certain measurements of static tension versus muscle length appear to corroborate this conclusion. On the other hand, there is direct evidence for the dynamic stability of muscle at longer lengths. The cross-bridge theory may be incorrect in this regard, and cross-bridges may contain a negative feedback mechanism; but it may be the case that the contradiction arises out of inappropriately extrapolating the static length-tension data to a dynamic situation. By monitoring the sarcomere length of a contracting muscle, it can be seen that shortening does not proceed smoothly, but in more or less discontinuous jumps. This “stepwise” shortening shows evidence of synchronization across a region of a muscle, and suggests some positive feedback process at work. Some speculations are offered as to possible mechanisms, including load-dependent signalling, diffusion, cooperative effects, and repeated cycles of substrate consumption, concomitant with shortening, alternating with a “catch-up” period of substrate production.

Notes: Abstract Electrical carotid sinus nerve stimulation (CSNS) via an implanted electrode receiver assembly, radio frequency coupled to an external signal generator, is an experimental therapy for hypertension and angina pectoris. CSNS increases afferent information to the central nervous system exerting neurally regulated decreases in heart rate, stroke volume, and blood pressure. No nonspecific side effects are observed, in contrast to drug therapy. A nerve pacemaker system is described and compared to the commonly used open-loop stimulator system (fixed frequency and intensity CSNS). It is a closed-loop system, controlled by heart rate (as an indicator of the state of “arousal” and of sympathetic activity) and, thereby, feedback-controlled by its therapeutic effects. The miniaturized (hybrid technology) system consists of an ECG amplifier, a stimulus pattern memory with I-O periphery and a transmitter, including an antenna coil to be coupled to the implanted assembly. Stimulus parameters (frequency and amplitude of impulses) are optimized for each patient individually. Stimulus patterns (pulse synchronous amplitude modulated groups of impulses) are adapted to the patient's cardiovascular situation. The nerve pacemaker may be an alternative to drug therapy or major surgery in both diseases. Compatible with the open-loop system, it replaces the first step in previously treated CSNS patients.

Notes: Abstract Intracranial pressure (ICP) monitoring is a critical measure for avoiding severe brain dysfunction or brain death by directing supportive therapy so as to prevent ICP increase severe enough to reduce cerebral blood perfusion. Such situations occur with brain swelling, increased cerebral vascular volume, and increase in cerebrospinal fluid (CSF) volume. Causes include ischemic stroke, subarachnoid bleeding, brain contusion, encephalitis (as in Reye's syndrome), and hydrocephalus from meningitis or neoplasm. When several days of ICP monitoring can direct resolution of the pressure crisis, the invasive direct connection of an intracranial sensor with external recording device carries only minimal infection risk. Prolonged ICP monitoring for weeks or months demands telemetry and becomes desirable in a number of chronic disease problems including both congenital and acquired hydrocephalus where enlarged and pressurized cerebral ventricles develop with reduced absorption of continuously secreted CSF. Although the primary disturbance in CSF circulation can remain incurable, its palliation by valve-regulated CSF diversions or shunting can restore normal brain function and in infants permit normal brain development. Missing this goal can result from failure to maintain a sufficiently normal pattern of CSF dynamics and ICP. Monitoring of the CSF pressure fluctuations transmitted through an intraventricular catheter provides the most accurate record of ICP pulsations. Therefore, a pressure sensing module can be “T'd” into an existing shunt system in continuity with the already placed ventricular tube. The capacity to monitor ICP accurately by telemetry was first established in dogs made hydrocephalic to assure free CSF pulse through a ventricular catheter (1,2,3, 4,5). The subsequent use of ICP monitoring by telemetry in three patients will be described.

Notes: Abstract In the consideration of systems for renal assist, several questions arise in relation to physiologic control achieved with a given system and design of optimum renal assist. Approaches to these problems require consideration of the available techniques, definition of treatment goals, i.e., how to monitor control, the application of models to better characterize a system and its behavior, and the application of new techniques or combinations of techniques to optimize renal assist. At present most renal assist systems involve membrane separation techniques as either hemodialysis and/or ultrafiltration. While most data concerning maintenance renal assist have been accumulated from these techniques, newer procedures have proved promising and include high permeability membrane techniques, such as hemofiltration, and sorptive techniques, such as direct hemoperfusion or dialysate regeneration. As an extension of these processes, one might also consider the role of plasmapheresis with plasma detoxification as a potential method to be considered for renal assist. The objective of the ideal support system is maintenance of the organism's biochemical constitution in as physiologic a state as possible. Thorough description of this state is necessary and must include normalization of body fluids, electrolytes, acid/base balance, and uremic “toxins”, and when used with models will aid in the development of optimum renal support systems.

Notes: Abstract A hypercomplex circulation and organs model of glucose and insulin dynamics is presented. The model is based on physiological parameters, incorporating blood and plasma flow rates, circulatory paths, intra- and extravascular glucose and insulin spaces, as well as the specific organs and tissues involved both with insulin disappearance and with glucose production or uptake. Its simulations readily lend themselves to physiological interpretation. To explore its validity, the model was assigned parameters typical of a 12 kg dog and was arranged to accept known glucose and insulin infusions from two different experiments on pancreatectomized diabetic animals. It predicted the observed glucose and insulin concentrations as well as uptake rates for both moieties in the individual organs and tissues. This confirmed the ability of the model to predict with consistency the group mean outcomes of both experiments when differing routes (portal or peripheral) of infusion were applied. Excellent agreement was achieved for the studies. The model isolates glucose uptake in the periphery, the liver, the brain, and the gut and allows a direct comparison of glucose disposal along various routes. Thus, the total amount of glucose uptake by peripheral, insulin-dependent tissues is directly calculated to be 30% of an intravenous glucose load, with peripheral infusion, which is higher than that with portal infusion (18%).

Notes: Abstract A combined oxygen consumption kinetics, used previously by other investigators, is utilized to calculate oxygen transport into heterogeneous tissue. When the oxygen partial pressure in the tissue decreases below a critical value, the oxygen respiration rate inside the cell decreases linearly with the partial pressure. Theoretical calculations of oxygen penetration depths into tissue show that the combined oxygen consumption kinetics gives considerably deeper penetration than zero-order consumption. The increase of the penetration depth is of the order of half the intercapillary distance in tissue. The results show that the form of the assumed oxygen consumption model is important in determining the depth of penetration into tissue, particularly in hypoxia.

Notes: Abstract A newly developed noninvasive tissue reflectance oximeter utilizes 5 light emitting diodes operating at the wavelengths of 0.635, 0.665, 0.795, 0.910, and 0.955 μ, and photodiodes to sample the tissue reflectance spectra. Since the tissue reflectance is affected by changes in both hemoglobin content (Hb T) and hemoglobin oxygen saturation (OS T),Hb T is first determined using the reflectance at 0.795 μ. The hemoglobinOS T is then estimated using the reflectances at the 5 wavelengths in conjunction with the diffuse reflectance equation which has previously been verified applicable to tissue reflectance oximetry. A quantitative estimation of bothHb T andOS T in intestinal mucosa of dogs obtained using this instrument showed thatHb T values agreed fairly well with those of others and that the standard errors ofOS T were around 5.0% inOS as compared with theOS values of blood samples for minimized arterial-venousOS differences. The continuous on-line measurement ofHb T andOS T should be possible using the reflectance technique and should be valuable for clinical evaluation of the patients.

Notes: Abstract The effect of small direct current (∼8μA) upon the tensile strength of the interfacial union between porous metal and polymer implants (100–200 μm diam pores) and bone was studied in the femur of dogs. The present results show that the electrical stimulation accelerates the rate of bony tissue growth into pores of the implants regardless of the nature of the materials tested. It is particularly exciting to find that the porous metal can be used as an electrode as well as an implant. This implies that an ordinary prosthesis made of metal can be made porous and the fixation time period can be shortened by the electrical stimulation. This has an enormous potential for all the direct fixation prostheses for rapid achievement of fixation.

Notes: Abstract Normalised autocorrelation functions were used to assess the variability of the contour scans produced from replicas of the skin surface of normal subjects. Systematic errors due to the presence of abnormal scans were detected by the occurrence of low values associated with specific scans. Mean harmonic coefficients were calculated and shown, by using the correlation technique, to be reliable representations of the skin surface contours.

Notes: Abstract A polarographic technique using flush mounted electrodes in the wall of a tube was used to measure augmentation of diffusion in flowing suspensions of bovine red blood cells in a region close to the tube wall. The effective diffusion coefficient was found to be an increasing function of particle Peclet number (based on the wall shear rate) and volume fraction of cells. Comparison of these results with experimentally measured diffusion augmentation in a system where wall effects were negligible provides information on the behavior of the cell-free skimming layer at the tube wall. The thickness of this skimming layer is dependent on the wall shear rate and on the bulk hematocrit. Below hematocrits of 25% the skimming layer thickness decreases with increasing wall shear rate, while above 25% hematocrit the skimming layer becomes thicker as the wall shear rate increases.

Notes: Abstract An automatic control scheme for the control of intra-aortic balloon pumping has been implemented on a Digital Equipment Corporation LSI-11 micro-processor system and tested in experiments conducted on a mock circulatory loop as well as in a series of acute animal experiments. The control algorithm employed by the digital controller (LSI-11) is identical in form to that employed by Clark et al. (3), and consists of [1] the beat-by-beat evaluation of a performance index that reflects the objectives of balloon pumping, and [2] the adjustment of balloon inflation and deflation times within the diastolic period so as to maximize this performance index according to a steepest ascent algorithm. In order to reduce convergence time and minimize disturbances around the optimum operating point, a scheme that reduces search step size as the search proceeds from initial values is also incorporated in the algorithm. Importantly, this system obeys a bedside measurement constraint in that it requires only readily available physiologic signals for its operation; the ECG for timing purposes, and the central aortic pressure for evaluation of the system performance index. A number of conventional safety features are also implemented in the controller to, for example, guard against untimely balloon inflation in the occurrence of aberrant heart beats. Finally, the ability of this digital controller to reach an optimum independent of the dynamics of the particular pneumatic pumping system utilized, coupled with the flexibility in design capability and relatively low cost of implementation via the microprocessor system, provide a significant advance in the area of the automatic control of intra-aortic balloon pumping.

Notes: Abstract The effects of unevenly distributed flow were investigated in a symmetrically branched tube with an angle of branching and branch-to-trunk area ratio that were comparable to the human descending aorta. Profiles of velocity were measured at the vertex of the bifurcation with a laser Doppler anemometer during pulsatile flow as well as steady flow. The mean Reynolds numbers were 500, 1000, and 1500. When flow in the branches was equal, reversals were present along the outer wall during the minimal phase of the flow cycle at a Reynolds number of 500. Such reversals were absent at higher Reynolds numbers. When flow in the branches was unequal, reversals occurred only in the branch with the lower flow. Such reversals occurred at all of the Reynolds numbers studied. Pulsatile flow separation, however, did not occur at any Reynolds number when the flow in the branches was equal. Pulsatile flow separation occurred in the partially occluded branch when flow in the branch was ≤8% of the total flow only at Reynolds numbers of 1000 and 1500. A prominent difference between pulsatile and steady flow was that reversals along the outer wall occurred during pulsatile flow at percentages that were prominently higher than the percentage of flow in the branch that produced reversals during steady flow. These observations may be pertinent to understanding the potential of characteristics of flow in the genesis of atherosclerosis in the region of the bifurcation of the aorta.

Notes: Abstract An ocular model is postulated to describe the refraction of microwaves (1 to 35 GHz) impinging on the eye from free space. Results from several semiempirical computations in which experimentally determined dielectric constants and electrical conductivities were incorporated into the model suggest that the focal point for an impinging paraxial beam of microwaves occurs a few millimeters behind the posterior center of the lens. The distance between the posterior center of the lens and the focal point is shown to increase with frequency, whereas the computed penetration depth of the lens at the anterior and posterior center is shown to decrease with frequency. A comparison between the model computations and experimentally induced cataractogenesis at various frequencies suggest that refraction is a significant factor in the lower frequency region (f〈5 GHz), whereas in the higher frequency region (f〉5 GHz) penetrationdepth effects become increasingly important.

Notes: Abstract The realization of effective neural prostheses requires both understanding of the neural physiological substrate of the function and the availability of hardware, stimulation electronics, electrodes, sensors, and information processing electronics, to execute the required function. Microelectronics, especially custom and semicustom integrated circuits, have effectively removed some of these barriers. Particularly in the area of implantable stimulation electronics, custom integrated circuits and advanced hermetic packaging techniques have been developed so that it is possible to make very small, long-lived multichannel stimulation systems. Similarly, the availability of low-power CMOS microprocessors, logic and memory components makes it possible to execute complex information processing in small, low-power portable systems. The principal technological bottlenecks in neural prostheses remain stimulation electrodes and physiological sensors. The techniques underlying microelectronic photolithographic fabrication may also make possible the “solution” of the electrode and sensor problems. In our auditory prosthesis project, we have photolithographic electrode arrays of both rigid and flexible character now nearing operational status. These electrodes are probably generalizable to a fairly wide number of prostheses applications. A number of sensors, especially those of pressure, motion and temperature, are also yielding to photolithographic fabrication. The sensor problem, however, for such physiologic parameters as ionic concentration remains the most difficult to conquer. Examples and illustrations of the state-of-the-art in these areas, as achieved by microelectronic techniques, will be given.

Notes: Abstract Root concepts of physiological regulation are introduced by reference to Claude Bernard (constancy of the internal milieu) and Walter B. Cannon (homeostasis). The key problem of process identification as constrained by the requirements of noninvasive measurement and analysis is cited. The nature of regulation, in general, and homeostasis, in particular, is considered. The dynamics of physiological regulation are exemplified by steady-state “limit cyclic”-type oscillations in mammalian metabolism. The notion of control is introduced to account for deliberate action by the organism to alter its own state or affect the state of its environment. The multilevel, multigoal scheme is illustrated in the context of respiratory regulation; a simile is drawn with the aircraft autopilot. Major scientific and technical developments over the period of 1960 to 1980 are high-lighted with mention of key individual and institutional prime movers.

Notes: Abstract Examples of clinical applications of neural control in the form of neural prostheses for effecting respiration and bladder evacuation are discussed with emphasis on methods of extending them from their present open-loop form to closed-loop systems. More advanced prostheses such as multichannel auditory prostheses and visual prostheses based on intracortical stimulation require the development of safer and more effective electrodes. Details of a promising new intracortical capacitor stimulating electrode are presented.

Notes: Abstract For the severely handicapped patient, such as a quadriplegic, a large number of independent signals would be desirable to control neuromuscular stimulators that could impart movement to the paralyzed limbs. We have investigated the possibility of making long-term connections to the central nervous system with microelectrodes. Monkeys have been implanted with arrays of intracortical electrodes for periods of up to 37 months, indicating that long-term connections to the nervous system are possible. A second question investigated was whether the implanted monkeys could learn to modify the firing patterns of recorded neurons to control a device outside of their bodies. Through the use of an 8 target tracking task a monkey was able to produce an information transfer rate of 2.45 bits/sec when cortical cell signals were the monkey's output. The same task was performed having the monkey move a handle by wrist flexion and extension (i.e., using the intact motor system as the output). The information transfer rate increased to 4.48 bits/sec, or less than a twofold improvement. Thus, the direct output of cortical cells can provide information transfer only moderately less precise than the intact motor system. Our preliminary studies have been encouraging on obtaining connections to the nervous system to control external devices. However, numerous improvements are required in electrode design, fabrication, implantation, and signal processing techniques before this method of obtaining control signals would be feasible for human applications.

Notes: Abstract The heart generates flow and pressure under four major controlling signals: end-diastolic volume (preload), ejection pressure (afterload), heart rate, and contractility. The control mechanism of each of these factors has been clarified by those investigators who first opened the hydraulic loop of circulation, studied the heart in a more or less isolated condition, but then put the acquired knowledge back in a proper perspective of the physiological closed-loop condition. Thus, combining Starling's law of the heart with the role of blood volume for venous return, cardiac surgeons began to use an aggressive infusion scheme for postsurgical patients. Recognition of the beneficial effect of reducing systolic pressure afterload has led cardiologists to carefully synchronized intraaortic balloon counterpulsation and, more recently, to an extensive use of vasodilator therapy. Ventricular pacing appropriately delayed from sensed atrial excitation, or even an automatic defibrillation, is now incorporated in an implantable pacer. The history indicates promising uses of closed-loop physiological control of cardiac contraction, including pharmacological closed-loop control of the contractility in the near future.

Notes: Abstract In health, both the total amount and the distribution of water and electrolytes in the body are controlled within narrow limits. While intercompartmental water fluxes depend solely on physical driving forces, the latter are determined by complex circulatory feedback mechanisms that manipulate capillary pressure, and by active transport mechanisms that affect intracellular osmotic pressure. Fluid and electrolyte intake are determined by central neural mechanisms. However, the fine tuning of body fluid and elctrolyte contact is accomplished by alterations in renal excretion controlled by a variety of local (intrarenal) mechanical and endocrine processes, as well as external neural endocrine feedback systems that include the antidiuretic hormone and the renin-angiotensin-aldosterone systems. Analysis of renal control is complicated by multiple interactions among the different control systems.

Notes: Abstract The Past—The artificial kidney, the bioengineering substitution of a biological system necessary to maintain life, comprises four subentities: hemodialysis, peritoneal dialysis, hemofiltration, and hemoperfusion. The main emphasis of this discussion will be on hemodialysis, however there are obvious corollaries with peritoneal dialysis, hemofiltration, and hemoperfusion and these will be discussed where relevant. The history and development of the four systems will be discussed. The Present—A better understanding of the limitations of artificial kidneys will be presented by a review of normal kidney function. A discussion of end-stage renal disease (ESRD) physiology and biochemistry including electrolyte metabolism and acid-base balance will be given. The Future—Initially, one might predict a continuing progression of technological sophistication applied to artifical kidney machines: microprocessor controlled functions such as osmolality changes, electrolyte homeostatis, and acid-base balance. However, the two distinct conceptually valid approaches for hemodialysis (and hemofiltration) are [1] daily or even continuous artificial kidney treatments and [2] increasingly sophisticated dialysis techniques used on an intermittent (thrice weekly) basis. These will be discussed in detail including uremic toxins, physiologic feedback controls and biochemistry servocontrols. The future of artificial kidneys is described as following two diverging courses. The first is that of daily or even continuous treatment, which renders redundant all but the simplest of servocontrol mechanisms. The second describes the evolution of logic of complex integrated closed-loop feedback controls for periodic artificial kidney treatments.

Notes: Summary Numerical solutions to the MHD Falkner-Skan equation and the corresponding heat transfer equation have been obtained on taking into consideration the effects of suction and injection and the pressure gradient parameter β. Velocity and temperature profiles are shown on graphs and the numerical values of the skin friction and the rate of heat transfer are given in the form of tables. It has been observed that an increase inN m (magnetic field parameter) leads to an increase in velocity, skin friction, rate of heat transfer and a fall in temperature. Also an increase in suction leads to a fall in the value of the skin friction and the rate of heat transfer, opposite to the case of injection.

Notes: Summary The extent to which a low-aspect-ratio flat ship with a chined hull is wetted when planing at infinite Froude number is investigated. A numerical method of solution for the wetted area, which is applicable to more general planing problems, is presented. The results obtained by this method are compared with those found by solving the inverse problem of determining the hull shape which produces a given waterplane shape and are shown to be in excellent agreement. Results are also presented which indicate that a ‘vertical’ chine may be used to fix the shape of the wetted region.

Notes: Summary Second-order rigid flapping response statistics of lifting rotor blades are obtained by a spatial correlation method for a general linear PDE with random forcing previously formulated by the author. These statistics enable us to analyze the effect of a finite correlation length of a spanwise nonuniform random excitation on the flapping blade response. For a random vertical inflow typical of turbulence excitation and for an advance ratio small compared to unity, this effect can be concisely expressed in terms of an amplitude factor and a phase factor. In the case of a spanwise correlation length of the order of the blade length, the amplitude factor shows that there may be as much as a 40% error in a solution which assumes the inflow is spatially uniform. The analytical development for a multi-mode solution illustrates how the spatial correlation method may be used in conjunction with a Galerkin procedure.

Notes: Summary Considered below are the high Reynolds number flows of an incompressible fluid, and their nonparallel stability properties, in certain plane channels whose widths vary slowly in the streamwise direction. The first approximation to the steady-state flow is governed by the classical boundary layer equations but with the pressure unknown. Solutions, some including separation and reattachment, to this are obtained numerically for a range of the parameters involved, and the stability of the resulting flows is considered using fixed frequency disturbances and taking into account the nonparallel nature of the basic flow by use of a W.K.B. method. The calculations yield critical Reynolds numbers, below which all the disturbances decay downstream, and for various Reynolds numbers above the critical values the growths of the small disturbances are calculated. The results are specialized to a particular class of channels which are straight far upstream and far downstream but vary in between. So the predictions should be much more easily amenable to experimental investigation and comparisons than those of the more idealized, diverging channel, flow problem studied by Eagles & Weissman [1] and the only other basic flow seriously studied from the viewpoint of nonparallel flow stability theory, the Blasius boundary layer. The results also represent the first application of both quasiparallel and slightly non-parallel stability theory to channels involving slowly varying but finite changes in width.

Notes: Summary A linear partial differential equation is derived to describe growth of an axisymmetric perturbation in the plastic buckling of axially compressed cylindrical shells. Simple J 2 flow theory is used along with rigid-plastic material behavior. An asymptotic solution is then constructed for large values of a parameter which characterizes localization of an initial imperfection. The perturbation remains localized. The solution is compared with experimental results.

Notes: Summary The storage of deformation energy in a bow with or without recurve is considered. Some numerical examples are discussed. For a simple bow it is shown that theoretically a shooting efficiency of hundred percent is possible.

Notes: Summary This paper deals with finding the stresses in steadily rotating limacon-shaped thin blades of homogeneous isotropic elastic material. The complex potentials, involving real parameters, have been obtained in closed form. Giving suitable values to the parameters involved, the solutions are derived for the following four positions of the axis of rotation: (a) the line of symmetry of the limacon, (b) any line perpendicular to the line of symmetry and lying in the plane of the blade, (c) any line passing through a point on the line of symmetry and perpendicular to the plane of the blade, (d) normal axis passing through the centroid. The hoop stress and its stationary points have been calculated in all the cases. The results have also been derived for circular blades. The numerical results are presented in the form of tables and graphs.

Notes: Summary A kinematic description is derived for plane strain deformations of unrestricted amplitude in an incompressible material ideally reinforced parallel to one axis of Lagrangian coordinates. The deformation is simply related to the configuration of one reference ‘fibre’. For a slab of uniform thickness, equations of motion are derived by integration over cross-sections. They relate the motion of the central fibre to the resultant tensile and shearing loads over each cross section. The equations predict that, in many materials, flexural waves may propagate. In this paper only elastic materials are considered. The simple wave solutions are discussed, showing how wave profiles may distort until a ‘crease’ forms at one surface of the slab. These creases play a role somewhat similar to shocks in gas dynamics. Some novel differences are revealed by an analysis of the equations governing deformations on either side of a crease.

Notes: Summary The right half-space Ω is bisected by a high-diffusivity planar sheet Γ which lies along the x-axis. A sudden increase in the potential on ∂Ω (y-axis) causes longitudinal diffusion along Γ coupled with transverse diffusion from Γ into Ω. Restricting to the case of large diffusivity ratio, Γ to Ω, it is demonstrated that the problem possesses a sequence of three distinct time domains in which self-similar solutions become asymptotically valid. The early, intermediate, and late solutions are each functions of only two independent variables; they are universally valid for all parameter values; and they are easily computed and readily applied. Transitions between asymptotics are described by expansions in time, the perturbations being regular in the early-intermediate period but singular in the intermediate-late period. The considered problem is a linear example which affords the opportunity for comparison with Fourier-Laplace analysis, and has application to thermal or electric conduction, diffusion mass transfer, and Darcy-flow of fluid in a fractured or layered porous medium. Methodology and qualitative observations are applicable to more complex nonlinear problems of the same class.

Notes: Summary Generalizing the idea of the deformable elastic shell model by Dick and Overhauser [1], a continuum model for thermoelastic diatomic elastic solids is presented. The model used is based on the assumption that a diatomic solid may be considered to consist of two simple and initially overlapping elastic media interacting with each other. Based on this assumption, the kinematics, balance laws and the appropriate constitutive relations for heat conducting diatomic elastic solids with multiple temperature are presented. For the illustration of the theory, the propagation of time-harmonic thermal waves in elastically rigid heat-conducting diatomic solids is studied and some particular cases are discussed.

Notes: Summary The problems of the flow of a viscous fluid past a micropolar fluid sphere and the flow of a micropolar fluid past a viscous fluid drop are discussed. The expressions for the stream functions, velocities, spins and the drag are obtained in each case and are compared with the classical (viscous fluid past a viscous fluid sphere) results. It is found that the viscosity ratios and the parameters, which arises in connection with the boundary condition, have significant effect upon the drag on the sphere in each case.

Notes: Summary Over a large range of the axial coordinate a typical higher-branch solution of the rotating-disk equations consists of a chain of inviscid cells separated from each other by viscous interlayers. In this paper the leading-order relation between two adjacent cells will be established by matched asymptotic expansions for general values of the parameter appearing in the equations. It is found that the relation between the solutions in the two cells crucially depends on the behaviour of the tangential velocity in the viscous interlayer. The results of the theory are compared with accurate numerical solutions and good agreement is obtained.

Notes: Summary Analyses are made for unsteady heat transfer from a circular cylinder immersed in a porous medium through which a liquid is flowing according to Darcy's law. Asymptotic solutions for large and small Peclet numbers (Pe) are obtained for the case where the unsteady temperature field is produced by a step change in wall temperature. The former is valid for Pe≳200 and the latter for Pe≲0.1. The series solution for small time, which is valid for all values of Pe, is also obtained. By applying the Euler transformation to the series, its convergence is greatly improved, and it appears that the Eulerized series determines the mean Nusselt number adequately for most values of time.

Notes: Summary In this paper, we tried to describe the diffraction of a solitary wave by a circular island, situated within an ocean of uniform depth. So we made the following assumptions: - the fluid, initially at rest, is homogeneous, incompressible and heavy - the bottom and the vertical outlines of the island are impermeable - the free surface is impermeable and it is an isobar. As a solitary wave cannot be described by means of the classic ‘Poincaré's small-parameter’ method, we used here the shallow-water theory. The small parameter ε represents the ratio of vertical to horizontal length scales. We replaced the cylindrical coordinates r, θ, z of a particle M by the following ones: % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXafv3ySLgzGmvETj2BSbqefm0B1jxALjhiov2D% aebbfv3ySLgzGueE0jxyaibaiGc9yrFr0xXdbba91rFfpec8Eeeu0x% Xdbba9frFj0-OqFfea0dXdd9vqaq-JfrVkFHe9pgea0dXdar-Jb9hs% 0dXdbPYxe9vr0-vr0-vqpWqaaeaabiGaciaacaqabeaadaqaaqGaaO% qaaiqadkhagaqeaiabg2da9iabgIGiolaadkhacaGGSaGafqiUdeNb% aebacqGH9aqpcqaH4oqCcaGGSaGabmOEayaaraGaeyypa0JaamOEai% aacYcaceWG0bGbaebacqGH9aqpcqGHiiIZdaGcaaqaaiaadEgacaWG% ObGaamiDaaWcbeaaaaa!50FD!\[\bar r = \in r,\bar \theta = \theta ,\bar z = z,\bar t = \in \sqrt ght \] Then, the problem amounts to calculating the function % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXafv3ySLgzGmvETj2BSbqefm0B1jxALjhiov2D% aebbfv3ySLgzGueE0jxyaibaiGc9yrFr0xXdbba91rFfpec8Eeeu0x% Xdbba9frFj0-OqFfea0dXdd9vqaq-JfrVkFHe9pgea0dXdar-Jb9hs% 0dXdbPYxe9vr0-vr0-vqpWqaaeaabiGaciaacaqabeaadaqaaqGaaO% qaaiqbeA8aMzaaraGaaiikaiqadkhagaqeaiaacYcacuaH4oqCgaqe% aiaacYcaceWG0bGbaebacaGGPaaaaa!44A7!\[\bar \phi (\bar r,\bar \theta ,\bar t)\] (the velocity potential, harmonic in the domain occupied by the fluid and satisfying the conditions imposed by our assumptions) and the free surface elevation denoted by % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXafv3ySLgzGmvETj2BSbqefm0B1jxALjhiov2D% aebbfv3ySLgzGueE0jxyaibaiGc9yrFr0xXdbba91rFfpec8Eeeu0x% Xdbba9frFj0-OqFfea0dXdd9vqaq-JfrVkFHe9pgea0dXdar-Jb9hs% 0dXdbPYxe9vr0-vr0-vqpWqaaeaabiGaciaacaqabeaadaqaaqGaaO% qaaiqadQhagaqeaiabg2da9iqbeE7aOzaaraGaaiikaiqadkhagaqe% aiaacYcacuaH4oqCgaqeaiaacYcaceWG0bGbaebacaGGPaaaaa!46B7!\[\bar z = \bar \eta (\bar r,\bar \theta ,\bar t)\]. We sought the solution in the form of power series in ε and we only calculated here the first approximation, by means of the Fourier transform. A numerical example was studied, allowing to illustrate our results with some curves.

Notes: Summary The flow of a uniform stream past an impermeable vertical surface embedded in a saturated porous medium and which is supplying heat to the porous medium at a constant rate is considered. The cases when the flow and the buoyancy forces are in the same direction and when they are in opposite direction are discussed. In the former case, the flow develops from mainly forced convection near the leading edge to mainly free convection far downstream. Series solutions are derived in both cases and a numerical solution of the equations is used to describe the flow in the intermediate region. In the latter case, the numerical solution indicates that the flow separates downstream of the leading edge and the nature of the solution near this separation point is discussed.

Notes: Summary This paper establishes an inversion formula for an integral transform of the Mellin type which is defined on a truncated infinite interval 0〈a≤r〈∞ and which is associated with a radiation type boundary condition atr=a.

Notes: Summary The method consists in integrating the Orr-Sommerfeld equation in the direction from the free stream toward the wall. In order to satisfy the boundary conditions at the wall, two linearly independent solutions have to be found. To prevent numerical solutions from becoming linearly dependent, the method of order reduction instead of repeated orthogonalization has been used. The method has been applied to calculate the neutral curve for the Blasius profile.

Notes: Summary The nonlinear partial differential equation of motion for an incompressible, non-Newtonian power-law fluid flowing over flat plate under the influence of a magnetic field and a pressure gradient, and with or without fluid injection or ejection, is transformed to a nonlinear third-order ordinary differential equation by using a stream function and a similarity transformation. The necessary boundary conditions are developed for flow with and without fluid injection (or ejection), and a solution for four different power-law fluids, including a Newtonian fluid, is presented. The controlling equation includes, as special cases, the Falkner-Skan equation and the Blasius equation.

Notes: Summary Free transverse vibration of a circular plate is considered by assuming the displacement components as an infinite series in the thickness coordinate. The analysis is done by retaining only the first two terms in each series. The equations of motion are derived by Hamilton's energy principle and the solutions are obtained in terms of Bessel functions. Numerical results are compared with the classical and shear theories which are particular cases of the present theory.

Notes: Summary The boundary layer over a flat plate of semi-infinite extent in a stratified and rotating flow grows forward from the trailing edge, and is characterized by an intrinsic length scaleL, which represents the distance from the trailing edge at which vortex stretching becomes just as important in the boundary layer as baroclinic vorticity production. Near the trailing edge, the layer is essentially the layer in a purely stratified flow; far upstream (manyL), it is an Ekman layer. The boundary layer entrains no fluid, but induces at its edge a transverse velocity component which drives an higher-order streamwise outer flow. If the flow is bounded above and below by horizontal planes, the Wiener-Hopf solution for this outer flow indicates that the disturbance decays rapidly downstream, but the transverse velocity component is non-zero far upstream.

Notes: Summary In a model of the Czochralski crystal growth system the crystal is represented by a solid rotating plane adjacent to a semi-infinite region occupied by the melt from which the crystal is grown. The melt itself may be subjected to rotation at large distances from the interface. In a co-ordinate system advancing with the interface the crystal growth is modelled by a ‘suction’ velocity at the interface. A transient analysis is performed following a discontinuous change of solute concentration in the bulk of the melt. Two cases are considered, namely (i) solid body rotation of crystal and melt and (ii) no melt rotation at large distances from the interface. The paper represents a re-examination and re-interpretation of earlier work by Burton, Prim and Slichter [1].