Effects of Hyperbaric Hypoxia on Some Enzyme Systems in the Mammalian Liver

The metabolic effects of hypobaric hypoxic stress on the mammalian liver were studied. The lactate dehydrogenase (LDH) and succinate dehydrogenase (SDH) activity of mouse liver homogenates were measured after exposure to an equivalent altitude of 36,000 feet and compared to controls kept at zero altitude. After six and twelve hour incubation periods, the altitude exposed samples demonstrated a significantly higher LDH activity than controls. SDH activity remained unchanged from controls after six hours but was significantly lower than controls after a 12 hour exposure to altitude. It is concluded that the changes in enzyme activity reflect a metabolic control mechanism attempting to maintain adequate energy production during periods of exposure to hypobaric hypoxic stress

Oxygen Toxicity in the Mammalian Liver

The effect of hyperbaric oxygen tensions on the oxygen consumption of mouse liver homogenates was investigated. It was found that hyperbaric oxygen rapidly inhibits the oxidative metabolism of the mammalian liver. Mouse liver homogenate exposed to an oxygen tension of 3837.8 mm Hg for 30 minutes demonstrated a 50.6% reduction in oxygen consumption compared to controls exposed to nitrogen at ambient pressure. The effects of reduced glutathione as a protective agent against hyperbaric oxygen toxicity were also examined. Liver homogenates pretreated with reduced glutathione and exposed to hyperbaric oxygen tensions demonstrated greater activity than untreated controls. It is concluded that: (1) Reduced glutathione protects important enzymes associated with oxidative metabolism by keeping them in a reduced and viable state, and (2) Reduced glutathione can stimulate oxygen consumption by increasing succinate formation through a reduced glutathione - succinate shunt

Latent Heat Storage with Phase Change Materials (PCMs)

Latent heat thermal energy storage with phase change materials (PCMs) is attractive since providing a high energy density storage due to the phase change by solidification/melting at constant temperature. Relative to sensible heat energy storage systems, latent heat storage with PCMs requires a smaller weight and volume of material for a given amount of captured/stored energy, and has the capacity to store heat of fusion at a constant or nearly constant temperature, thus maintaining a high and constant temperature difference between the heat exchanging surface and the PCMs.The present review paper will summarize the required properties of PCMs, with their respective advantages and disadvantages; the current state of development and manufacturing; the development of PCM applications, including their incorporation into heat exchangers, insertion of a metal matrix into the PCM, the use of PCM dispersed with high conductivity particles. PCM uses will be illustrated through some case-studies

On-line scheduling method of manufacturing system based on VS algorithm for reference pattern

In this paper, a scheduling method is developed provide planning for manufacturing plants with multiple coordinating cells. The controls for reconfigurable manufacturing systems have to be capable not only of identifying exceptions on-line, but also simultaneously developing on-line strategies for unpredictable customer order changes or inaccurate estimate of processing times. The approach exploits virtual supervisor (VS) concept developing an algorithm which provides access to all system information during program execution and thus can readily monitor the overall system performance creating reference pattern. The goal is to minimize expected costs of part tardiness and/or earliness. A solution methodology based on a combined Lagrangian relaxation, VS-Patterns, Maxwell equations and temporal difference is developed to reduce the computational requirements for large problems. Sequences pattern shows that near optimal schedules can be obtained a dual solution for on-line implementation

Determination of atmospheric mercury during the North Sea experiment

Total gaseous mercury (TGM) and rainwater were collected on board of two research vessels (F. S. ALKOR and R.V. BELGICA) positioned 200 km apart in the center of the North Sea during the North Sea Experiment, September 1991. On the F. S. ALKOR (up-wind ship) TGM concentrations ranged from 0.7 to 2.6 ng.m(-3) with an average of 1.5 ng.m(-3) and on the R. V. BELGICA (down-wind ship) TGM ranged from 0.7 to 1.9 ng.m(-3) with an average of 1.2 ng.m(-3). An average 20% decrease is observed from the up-wind to the downwind ship. which may largely be affected by entrainment into the free troposphere. An overall removal (entrainment) velocity of 0.95 cm.s(-1) was calculated for the whole experiment. The average removal velocity was 0.5 cm.s(-1) for dry periods and varied between 1 to 5 cm.s(-1) during rain events. Rainwater concentrations varied between 5 and 25 ng.l(-1). Based on these data an annual wet deposition flux of 1.08 ng Hg cm(-2) yr(1-) was estimated for the North Sea

An Approach to Line Balancing on Virtual Supervisor Induction Method and Intelligent Agents

This approach develops a method for solving the line-balancing problem, which is based on two stages. The works in a first stage is to identify the task of workstation, the assignment of the tasks to stations on the line and the recognized balance delay. In this stage we propose the induction VS method, which allows further identify the exact position between pieces, machine into a workstation and also between extern workstation, as well as intracellular and intercellular part. This way each task is identified and measured. In the second stage is to carry out a macro-approach to choose the resource to perform each of them. The hybrid intelligent agent architecture is proposed for this second stage, which has consideration of machining sequence. The integration between both technologies allows us to develop new hybrid architecture capable to reduce the computational time in the deliberative layers fundamentally. Finally, a reconfigurable testbed has been proposed for future experiments and results to evaluate this new balancing method. Some previous computational experiments provide that the proposed approach is efficient to solve practical transfer line design for balancing problem

The impact of trust on private equity contracts

This paper adresses the impact of trust on private equity contracts. Trust between investor and entrepreneur is essential to help overcome control problems, especially in an environment with severe agency risks and incomplete contracts. In this study, information about the effects of trust is collected using a simulation with 144 entrepreneurs and investors. We find that trust has an impact on the desired contracts of entrepreneurs, but not on that of investors. Our findings suggest that for parties, faced with potentially large agency problems (investors), trust and control seem to play complementary roles. On the other hand, for parties faced with smaller agency problems (entrepreneurs), trust seems to be a substitute for control

Connectivity between migrating and landlocked populations of a diadromous fish species investigated using otolith microchemistry

Smelt Osmerus eperlanus has two different life history strategies in the Netherlands. The migrating population inhabits the Wadden Sea and spawns in freshwater areas. After the closure of the Afsluitdijk in 1932, part of the smelt population became landlocked. The fresh water smelt population has been in severe decline since 1990, and has strongly negatively impacted the numbers of piscivorous water birds relying on smelt as their main prey. The lakes that were formed after the dike closure, IJsselmeer and Markermeer have been assigned as Natura 2000 sites, based on their importance for (among others) piscivorous water birds. Because of the declining fresh water smelt population, the question arose whether this population is still supported by the diadromous population. Opportunities for exchange between fresh water and the sea are however limited to discharge sluices. The relationship between the diadromous and landlocked smelt population was analysed by means of otolith microchemistry. Our interpretation of otolith strontium (88Sr) patterns from smelt specimens collected in the fresh water area of Lake IJsselmeer and Markermeer, compared to those collected in the nearby marine environment, is that there is currently no evidence for a substantial contribution from the diadromous population to the spawning stock of the landlocked population

THREE DIMENSIONAL ARTHROKINEMATIC ANALYSIS OF THE LATE PREPARATORY PHASE OF HANDBALL THROWING

INTRODUCTION: At full cocking, functional instability of the glenohumeral (GH) joint is commonly found in handball players. In the past, 2D radiography was used to examine the in vivo translation of the humeral head (HH) on the glenoid cavity (GC). Considering the restraint validity of 2D methods to estimate 3D motion, 3D intra-articular GH kinematical data were obtained on the late cocking phase of handball throwing, using fast helical CT scanning. METHODS: Based on the CT data, 3D bone reconstructions of 3 asymptomatic and 3 functionally unstable GH joints (1 internal impingement, 2 with minor anterior GH instability) in handball players were acquired from a position with the shoulder in 90° abduction and 90° external rotation, and from a position of full cocking assessed on an individual basis. Kinematic analysis was based on a least squares method and linked to the finite helical axis (FHA) concept. After virtual disarticulation, a local frame was embedded on the GC. Subsequently, the GH FHA parameters of direction, rotation and shift were decomposed on this local frame. The displacement of the center of curvature of the HH was related to the GC. Based on an analytic error propagation model, the estimates of the rotation angle, the direction vector and the shift showed highly accurate results. The estimate of the position vector was insufficient for a mathematical analysis and therefore obtained graphically in the finite plane of motion, perpendicularly situated on the FHA. Subsequently, GH contact areal displacement of the mating articular surfaces was analyzed in this finite plane of motion. RESULTS: Towards full cocking, the HH of the asymptomatic shoulders practically did not externally/internally rotate on the local GC frame. The internal impingement demonstrated an accentuated GH external rotation, attended by a dysfunction in scapular setting, with a normal posterior translation of the HH on the GC. Minor anterior GH instability showed a diminished posterior translation of the center of the HH on the GC, as well as an accentuated external rotation. GH contact areal displacement in the normal throwing shoulders and the test case with internal impingement revealed roll behavior. The test cases with minor anterior GH instability featured a pivot. CONCLUSIONS: This research demonstrated the use of helical CT data reconstruction of joint structures with the implementation of an FHA approach to study the 6 degrees of freedom of intra-articular motion assessing a local articular embedded frame and contact areal displacements. The study provided insight in the arthrokinematics of functional instability of the GH joint at late cocking