Modeling fixed-bed drying of bark

A model for fixed-bed drying of bark has been developed. The model takes heat and mass transfer between the air and bark into account and the volumetric heat transfer coefficient was used as fitting parameter in the model. The assumption of adiabatic saturation of the air leads to too high drying rates but a model with three size fractions shows good agreement both between experimental laboratory data and data from an industrial dryer. A sensitivity analysis for different air temperatures, air velocities, and bed heights show how the dryer capacity depends on these parameters.     

CFD simulation on the air flow in a sauna

Sauna is the Finnish word for a wood-lined and insulated room, heated by a special stove containing stones, and erected specifically to create the right environment for a certain kind of dry bath. Its fundamental purpose is to induce perspiration and thus to cleanse the skin and body. The authors have now applied scientific data to the mystique and culture of the often misunderstood Sauna which has been used by the Finns for some two thousand years.     

The cost-effectiveness of routine postoperative radiotherapy after sector resection and axillary dissection for breast cancer stage I. Results from a randomized trial

BACKGROUND: Cost-effectiveness of routine postoperative radiotherapy after breast-conserving surgery has not been prospectively evaluated earlier. In times of rationing of medical resources, valid assessments of cost-effectiveness are important for rational allocation of resources. PURPOSE: Cost and cost-effectiveness of routine postoperative radiotherapy was calculated in a prospective randomized trial comparing sector resection plus axillary dissection with (XRT group) or without (non-XRT group) postoperative radiotherapy in breast cancer stage I. Three hundred eighty-one patients were included. After a median follow-up of five years 43 local recurrences, six of them in the XRT-group occurred (P < 0.0001). No difference in regional and distant recurrence (P = 0.23) or survival (P = 0.44) was observed. PATIENTS AND METHODS: Direct medical costs as well as indirect costs in terms of production lost during the treatment period and travel expenses were estimated from data in the medical records and the national insurance registry of each patient. Average costs of different treatment activities and measures were estimated for the XRT-group and the non-XRT group respectively. From these estimates differences in costs and effectiveness between the groups were calculated and marginal cost-effectiveness ratios were estimated. For the construction of QALYs each life-year was quality-adjusted by a utility value depending on which health state the patient was considered to perceive. RESULTS: Taking into account the cost of primary treatment, the cost of follow-up, the cost of treatment of a local recurrence, travel expenses and indirect costs (production lost) excluding costs for treatment of regional and distant recurrence the cost per avoided local recurrence at five years was SEK 337,727 ($44,438, Pounds 27,018). Adjustment for quality of life showed a cost for every gained QALY to be SEK approximately 1.6 million, ($210,526, Pounds 128,000), range SEK 0.2-3.9 million ($26,315-513,158, Pounds 16,000-312,000). CONCLUSION: The cost of routine postoperative radiotherapy after sector resection and axillary dissection in breast cancer stage I per avoided local recurrence and gained QALY is high. The cost per gained QALY show great variation depending on utility value, which in this study was derived from external observers and not from the patients themselves. These results stress the importance of identifying risk factors for local recurrence, better understanding of impact on quality of life of a local recurrence and adding cost evaluations to clinical trials in early breast cancer.     

Effect of eicosanoid inhibition on the development of pulmonary edema after acute lung injury

In experimental models of acute lung injury, cyclooxygenase inhibition improves oxygenation, presumably by causing a redistribution of blood flow away from edematous lung regions. This effect on perfusion pattern could also reduce alveolar edema formation. On the other hand, pulmonary pressures usually increase after cyclooxygenase inhibition, an effect that could exacerbate edema accumulation. Therefore we tested the following hypothesis: the total accumulation of pulmonary edema in dogs during a 24- to 28-h period of observation after acute lung injury caused by oleic acid will be less in a group of animals treated with meclofenamate (n = 6) or with the thromboxane-receptor blocker ONO-3708 (n = 5) than in a group of animals treated with oleic acid alone (placebo, n = 6). Lung water concentrations (LWC), the regional pattern of pulmonary perfusion, and protein permeability were measured with the nuclear medicine imaging technique of positron emission tomography. After 24-28 h, LWC was significantly less (P < 0.05) in the ONO-3708 group than in the meclofenamate group (a similar trend was seen compared with the placebo group, P = 0.12). After 24-28 h, pulmonary arterial pressures were highest in the meclofenamate group. Regardless of group, the only significant correlation with the change in LWC was with the integral of pulmonary pressures over the 24- to 28-h period. The data suggest that thromboxane inhibition will reduce edema accumulation in acute lung injury but that this effect depends on reducing as much as possible the simultaneous development of pulmonary hypertension from other causes.     

Loss-compensated optical Y-branch switch in InGaAsP-InP

An InGaAsP-InP loss-compensated Y-branch switch is demonstrated. Integrated amplifying sections compensate for internal losses. The operating wavelength is 1.3 μm, and the gating dynamic range is 35 dB. A study of similar devices indicates that a gain of more than 10 dB and a gating dynamic range in excess of 45 dB are feasible     

Procedures for parameter and state estimation of microbial growth process models

Practical problems concerning parameter and state estimation of microbial growth processes, with application to batch and continuous fermentation processes and to the activated sludge wastewater treatment process are discussed. Besides the usual aggregated single substrate-single organism mass balance model with Michaelis-Menten growth dynamics, an alternative model, in which the biomass concentration is divided into age classes, is introduced. A method in which the parameters were adjusted manually with sensitivity functions was used for parameter estimation. With the aid of some examples it was shown that the Michaelis-Menten model is not practically identifiable. A recursive state-estimation algorithm for control and supervision purposes was developed and its application in combination with both the aggregated and the age distribution model was demonstrated.     

Modelling of the Indoor Environment – Particle Dispersion and Deposition

Abstract A three-dimensional drift-flux model for particle movements in turbulent airflows in buildings is presented. The interaction between the carrier air and the particles has been treated as a one-way coupling, assuming the effect of particles on air turbulence is negligible due to low solid loadings and comparatively small particle settling velocities. Turbulence effects are modelled with a standard κ-? model. Wall functions are applied at near-wall grid points. Aerosol measurements carried out under turbulent room flow conditions are used to validate the numerical calculations. Several particle size distributions are considered in the simulations. The model is then applied to mixed flow conditions in a room, as well as to homogeneous air supply conditions around a human body. The flow fields and particle distributions are analysed. Close to a standing person, the particle distribution pattern from a downstream point source is strongly dependent on the ventilation air supply rate. This has been confirmed by experiments reported in the literature.