Aims: To evaluate a thin and soft multifunctionalcatheter for the simultaneous real time monitoring of leftventricular volume and pressure with special consideration toside elTects such as interference with normal cardiacelectrophysiology.Methods and results: In four pigs, pressure and volumewere simultaneously recorded by using the thin single segmentpressure and conductance catheter. Measurements were doneunder varied cardiac conditions: at baseline, during preloadreduction and afterload Increase. Volumes were calibrated withintracardiac ultrasound measurements. During preloadreduction the pressure and volume decreased as expected. Acautious afterload increase resulted in a corresponding pressureand volume increase, the maximum of the pressure curvechanged from early to late. Both SV and EDV increased. Thevery few arrhythmias were mainly caused by surgicalinterference.Conclusion: The present study demonstrates that our thinsingle segment conductance catheter for the simultaneousmeasurement of LV volume and pressure has a performancethat warrants further development with the goal to make themethod available for human use. In particular, the catheter didnot cause any arrhythmias.
The behaviour of particles in air flow is important for identifying those in various locations in ventilated space. The main reason for this study is to propose a new modelling concept to determine a realistic distribution of particles of different sizes in a space. The goal for this investigation is to divide particles into groups according to their behaviour in air and to improve the existing settling model. The growth of particle aerodynamic diameter in higher relative humidity is also presented. Here, growth of diameter and coagulation is used to determine the control volume concentration. The finite volume method is used to describe the particle concentration in the computational domain. A background to particle properties and theory for calculations are given for this purpose. Results from the literature survey reveal that modelling needs a more systematic approach to cover all sizes of particles with clear classification by behaviour.
Several studies based on analytical models and numerical simulations have shown that it is difficult to control airborne particle movements in a ventilated room. However, more knowledge and information on particle characteristics and particle movements, in combination with new numerical simulation tools, have recently made it easier to estimate particle patterns. In the present paper new information is used to evaluate the role of filtration and ventilation in the particle elimination process. Key parameters found include the particle aerodynamic diameter and the particle settling velocity governed by Stokes formula. Particle dispersion and settling are highly dependent on the ventilation airflow structure. Calculations with CFD (Computational Fluid Dynamics) show characteristic patterns of particle movements in rooms with displacement ventilation.
Particle removal efficiency in a ventilated room is investigated. This paper reports the differences in particle removal efficiency with various locations of supply and exhaust devices. Numerical simulations are carried out in a simple test room to illustrate the particle concentrations with different configurations of room ventilation. Several particle sizes are used and the influence of different flow patterns and air change rates are investigated. Particles are supplied to the room with the incoming air. Isothermal conditions with varying air supply velocities are used. Preliminary results indicate that particle removal efficiency is not predominantly influenced by air exchange rate, also the location of the supply/exhaust device is underestimated as an indicator of ventilation effectiveness.
Rising energy prices have contributed to the development of heat pump-based heating systems in Sweden. Low flow temperature in the secondary heat distribution system to rooms is a requirement for energy-efficient systems. This increases the thermal efficiency of the heat pump and decreases thermal losses in the distribution system. Flow temperatures in water-based systems for heat distribution in buildings have been decreased from 55°C to temperatures around 30°C. This is to maximize the efficiency of heating systems that are based on heat pump technology. Different technical solutions have been suggested to guarantee space-heating requirements with low temperature difference between heating units and ambient air. Floor heating has in many cases been considered a good option, and the popularity of such systems has dramatically increased. Complicated installation work, moisture problems and slow thermal control with floor heating are reasons enough to find alternative low-temperature units for heat distribution in rooms. This may result in a combined heating and ventilation system that operates with forced convection.
The chemical bonding and geometric structure of acetylene adsorbed on Cu(I 10) is analyzed using X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS) and X-ray emission spectroscopy (XES) in combination with density functional theory (DFT) total energy geometry optimizations and spectral calculations. XPS reveals two different adsorbed species at liquid nitrogen temperature. The molecular alignment is deduced from angle-resolved XAS, revealing that in one site the molecules are aligned with the C-C axis along the [0 0 1] direction and in the other site with an average angle of 35degrees to the Cu rows. The position of the shape resonance is used to deduce a C-C bond length of 1.35 Angstrom, which is close to the values obtained from the DFT geometry optimizations. XES reveals strong sigma-pi mixing and new occupied states close to the Fermi level, originating from the out-of-plane pi* orbital, which becomes occupied upon adsorption in agreement with the Dewar-Chatt-Duncanson model of the bonding.
For most knowledge-intensive companies at present, the business environment where they compete is complex, characterized by rapid change and uncertainty. Employees and other intangible resources (i.e. intellectual capital) generally represent the most critical resources in the value creation process. Crafting strategy in such contexts is not helped by conventional models and tools of strategy. The assumptions which underpin many of them do not hold in the present competitive environment, making them at best irrelevant, but at worst leading to the development of strategies that can put the success of a company in jeopardy. New metaphors for describing these companies and their competitive realities, as well as tools for navigating in them, are required, if the strategy discipline is to remain relevant for practitioners. In this paper, it is suggested that the intellectual capital perspective can provide a bridge to the practical application of a vision- and values-based strategy through the notion of embodying strategy in organizational resources. A conceptualization of strategy, that links strategy, identity and intellectual capital, more suitable to knowledge-intensive companies competing in uncertain environments, is introduced and described.
The objective of this paper is to investigate how to best position the sensing electrodes on a single segment conductance catheter, and to calculate the expected performance. Using electrode potential data, obtained with the present five segment conductance catheter in pig experiments, we have interpolated the electrical field at any given point of time, and calculated what volume curve to expect with only two sensing electrodes. Comparison shows that the deviation between our calculated method and the present one is stable and small. Mean deviation with optimized electrode positions was 0.05% per sample, and the maximum deviation found for a single time sample was 2.57%. This indicates that it is possible to build a thin single segment catheter with as good performance as for the present five segment conductance catheter.