COMPREHENSIVE STUDY OF THE GAS HOLD UP AND BUBBLE SIZE DISTRIBUTION IN HIGHLY VISCOUS LIQUIDS II. CMC SOLUTIONS

Following properties of short bubble columns employing CMC solutions (1.0, 1.4 and 2.0%) and perforated plates (0.5, 1.0 and 3.0 mm hole diameters) were determined: relative mean gas hold up, E_G, bubble size distribution, Sauter bubble diameter, d_s, and the specific geometrical bubble surface areas, a' and a' due to the “intermediate to large bubbles.” The a' values were compared with the corresponding volumetric mass transfer coefficients, k_La's and the mass transfer coefficients, k_L, were estimated. The properties of these systems were investigated as function of the superficial gas velocity, W_SG, CMC concentration and aerator type.     

Understanding users and their needs

Gaze-control enables people to control a computer by using eye-gaze to select items on screen. Gaze-control is a necessity for people who have lost all motor control of their body and only have control over eye movements. In addition, gaze-control can be the quickest and least tiring option for a far broader group of people with varying disabilities. This paper reports findings from gaze-control user trials involving users from both groups: people who are totally paralyzed, as well as people with a wide range of complex disabilities. The trials conducted involved four different centres supporting people with disabilities in three different European countries. Several gaze-control systems were trialled by a large number of users with varying needs and abilities. The perceived benefits of gaze-control are described, and recommendations for successful assessment and implementation of gaze-control are provided.     

Interaction of transport resistances with biochemical reaction in packed-bed solid-state fermentors: effect of temperature gradients

Subdermal superficial liposuction, first presented by the authors at the ISAPS Congress at Zurich in 1989, is performed with thin three-hole Mercedes cannulas (diameter ranges from 1.8 to 2 mm) to treat small and secondary adiposities and to allow better skin retraction. Suction of the subdermal layer of fat reduces the thickness and consistency of the superficial fat and enhances the possibility of skin retraction. In cases where there is a large adiposity of the abdomen, arms, or inner thighs, there is a conspicuous volume of fat whose weight tends to overstretch and to carry the overlying skin downward. In these cases we need to reduce the large fat volume to permit effective skin retraction. Therefore, we apply the principles of traditional liposuction with those of subdermal superficial liposuction to aspirate large amounts of fat from all the adipose layers. We call this technique Massive All Layer Liposuction (MALL). The amount of skin shrinkage after this "defatting" procedure is remarkable and the clinical results are very good. The MALL technique can be applied to other areas as well. In our experience this new liposuction technique has dramatically reduced the indications of abdominoplasties and dermolipectomies of inner thighs and arms.     

Isoseparation curves: a mechanism for optimizing off-axis dose homogeneity of intact breast irradiation

The purpose of this paper is to determine whether using off-axis isoseparation curves to optimize the collimator rotation angle improves dose homogeneity. Eleven intact breast irradiation patients underwent computerized tomography (CT) treatment planning with 1 cm abutting slices. Central plane treatment planning, using 6 MV photons, tissue inhomogeneity corrections, and isocentric opposed tangent treatment fields, was performed. Collimators were rotated to match chest wall slope through the use of a beam's-eye-view setting. Patient separations were measured from the apex of the breast to the posterior field border on each axial CT slice. Sagittal-plane isoseparation curves were constructed from these measurements. Using these curves, the collimator rotation that minimized off-axis separation differences was determined. A comparison of off-axis dose inhomogeneity was performed for patients with a > or =10 degrees difference between this optimized collimator angle and the angle determined by chest wall slope. These comparative treatment plans differed only with respect to collimator angle rotation. The mean optimal collimator rotation angle differed significantly from the mean rotation angle which matched the chest wall slope (5.4 degrees vs. 11 degrees, respectively, P < 0.001). Four of the 11 patients had rotation angle differences of 10 degrees. In these patients, the optimization of collimator angle reduced the percentage of breast volume to "that" received > or =110% of the prescribed dose. For the patient with the largest breast size to the patient with the smallest breast size the decreases were, respectively, 5% (15% to 10%), 3% (24% to 21%), 1% (4% to 3%), and 1% (0.9% to 0%). The mean reduction in dose inhomogeneity was greatest in the inferior breast quadrants. At 6 cm and 4 cm off axis, the mean reductions in the percentages of the breast tissue to "that" received 110% of the prescribed dose were respectively 15.1% and 5.3 %. Optimizing the collimator angle through the use of isoseparation curves decreases dose inhomogeneity. The greatest improvements are in the inferior quadrants of the intact breast. The improved dose homogeneity may have clinical relevance in the treatment of patients with large breast sizes.     

Model Checking for a Class of Weighted Automata

A large number of different model checking approaches has been proposed during the last decade. The different approaches are applicable to different model types including untimed, timed, probabilistic and stochastic models. This paper presents a new framework for model checking techniques which includes some of the known approaches and enlarges the class of models to which model checking can be applied to the general class of weighted automata. The approach allows an easy adaption of model checking to models which have not been considered yet for this purpose. Examples for those new model types for which model checking can be applied are max/plus or min/plus automata which are well established models to describe different forms of dynamic systems and optimization problems. In this context, model checking can be used to verify temporal or quantitative properties of a system. The paper first presents briefly our class of weighted automata, as a very general model type. Then Valued Computational Tree Logic (CTL) is introduced as a natural extension of the well known branching time logic CTL. Afterwards, algorithms to check a weighted automaton with respect to a CTL) is introduced as a natural extension of the well known branching time logic CTL. Afterwards, algorithms to check a weighted automaton with respect to a CTL formula are presented. As a last result, bisimulation equivalence is extended to weighted automata and CTL$.     

Physical ergonomic hazards in highway tunnel construction: overview from the Construction Occupational Health Program

This report provides an overview of physical ergonomic exposures in highway construction work across trades and major operations. For each operation, the observational method “PATH” (Posture, Activity, Tools and Handling) was used to estimate the percentage of time that workers spent in specific tasks and with exposure to awkward postures and load handling. The observations were carried out on 73 different days, typically for about 4 h per day, covering 120 construction workers in 5 different trades: laborers, carpenters, ironworkers, plasterers, and tilers. Non-neutral trunk postures (forward or sideways flexion or twisting) were frequently observed, representing over 40% of observations for all trades except laborers (28%). Kneeling and squatting were common in all operations, especially tiling and underground utility relocation work. Handling loads was frequent, especially for plasterers and tilers, with a range of load weights but most often under 15 pounds. The results of this study provide quantitative evidence that workers in highway tunnel construction operations are exposed to ergonomic factors known to present significant health hazards. Numerous opportunities exist for the development and implementation of ergonomic interventions to protect the health and safety of construction workers.     

TimeLapseAnalyzer: multi-target analysis for live-cell imaging and time-lapse microscopy

The direct observation of cells over time using time-lapse microscopy can provide deep insights into many important biological processes. Reliable analyses of motility, proliferation, invasive potential or mortality of cells are essential to many studies involving live cell imaging and can aid in biomarker discovery and diagnostic decisions. Given the vast amount of image- and time-series data produced by modern microscopes, automated analysis is a key feature to capitalize the potential of time-lapse imaging devices. To provide fast and reproducible analyses of multiple aspects of cell behaviour, we developed TimeLapseAnalyzer. Apart from general purpose image enhancements and segmentation procedures, this extensible, self-contained, modular cross-platform package provides dedicated modalities for fast and reliable analysis of multi-target cell tracking, scratch wound healing analysis, cell counting and tube formation analysis in high throughput screening of live-cell experiments. TimeLapseAnalyzer is freely available (MATLAB, Open Source) at http://www.informatik.uni-ulm.de/ni/mitarbeiter/HKestler/tla.     

Queueing Petri nets with product form solution

The product form results recently published for stochastic Petri nets are combined with the well-known product form results for queueing networks in the model formalism of queueing Petri nets yielding the class of product form queueing Petri nets. This model class includes stochastic Petri nets with product form solution and BCMP queueing networks as special cases. We introduce an arrival theorem for the model class and present an exact aggregation approach extending known approaches from queueing networks.