Filtyp
In this study a plate-fin type Compact Heat Exchanger (CHE) is considered for optimization. The optimization method uses a Genetic Algorithm (GA) to search, combine and optimize structure sizes of the CHE. The minimum total volume or/and total annual cost of the CHE are taken as objective functions in the GA, respectively. The geometries of the fins are fixed while three shape parameters are varie
The admission control mechanism is an important part of many communication systems. In this paper we investigate load control mechanisms for server systems, that is systems that may be modelled as queueing systems. We show how control theory can be used when designing controllers for a G/G/1-system. We design a PI-controller for the system and compare the steady-state and transient behavior of thi
Every tripotent e of a generalized Jordan triple system J of order I uniquely defines a decomposition into the direct sum of l(2) + 2l components. This decomposition generalizes the known Peirce decomposition of a Jordan triple system and of a generalized Jordan triple system of second order, and is the first step in determining the structure of a generalized Jordan triple system in terms of the t
The stability of a colloidal solution consisting of a mixture of charged spherical aggregates and polyampholytes is investigated by means of Monte Carlo simulations. The double-layer repulsion between the charged macroions is reduced upon addition of neutral polyampholyte and for sufficiently highly charged colloids it is converted into a net attractive interaction. Attractive interactions can als
Female moths generally use pheromones to attract males. Normally, all females in a population produce a specific chemical blend with only a limited variance, and the local males are highly attracted to this blend. To better understand the direct and indirect selective forces acting on this communication system, where, unusually, it is the reproductively limited sex that signals for matings, a popu
We examine the dynamics of two bright solitary waves with a negative nonlinear term. The observed repulsion between two solitary waves-when these are in an antisymmetric combination-is attributed to conservation laws. Slight breaking of parity, in combination with weak relaxation of energy, leads the two solitary waves to merge. The effective repulsion between solitary waves requires certain nearl
Developmental instability and fluctuating asymmetry (FA) describe the inability of organisms to correct for random accidents under development and has become a major but controversial topic in evolutionary biology. Theoretical models predict that the level of FA should increase as a result of inbreeding, but empirical results are ambiguous. Moreover, the relationship between fitness and FA is stil
Although the Normalized Difference Vegetation Index (NDVI) time-series data, derived from NOAA/AVFIRR, SPOT/VEGETATION, TERRA or AQUA/MODIS, has been successfully used in research regarding global environmental change, residual noise in the NDVI time-series data, even after applying strict pre-processing, impedes further analysis and risks generating erroneous results. Based on the assumptions tha
A BCR/ABL-negative chronic myeloid leukemia (CML) with t(12;14) (p12;q11-13) as the sole chromosomal abnormality was investigated by fluorescence in situ hybridization (FISH), which disclosed a cryptic insertion of ETV6 (previously called TEL), located at 12p12, into ABL at chromosome band 9q34. ETV6/ABL fusion was confirmed by RT-PCR, revealing that the first five exons of ETV6 were fused in fram
In this paper the joint density of waveheight and half-wavelength is considered for waves observed at a fixed time point and encountering waves that are overtaking a ship from behind. The densities for these two cases are related by a Doppler shift, expressed in terms of the relative velocity of the waves and the ship. Based on this observation, an approximation of the encountered density is propo
Forty-six patients (48 hips), operated on with cemented total hip arthroplasty (THA) because of arthrosis, were examined radiographically and sonographically at 10-year follow-up. Polyethylene wear of acetabular cups was measured on conventional non-weight-bearing pelvic radiographs, and the volume of polyethylene debris was calculated. Radiographic signs of loosening were identified. The capsular
Characteristics and origin of the aerosol in the lowermost stratosphere at northern midlatitudes were studied using measurements from a passenger aircraft ( Civil Aircraft for Regular Investigation of the Atmosphere Based on an Instrument Container, or CARIBIC). Aerosol samples were collected during 60 intercontinental flights during 1999 - 2002 and analyzed for elemental composition with particle
BACKGROUND: High blood pressure contributes to organ damage. However, during the past two decades there have been great advances in the medical treatment of hypertension. Technical progress has also made it easier to visualize organ damage. Hence we found it of interest to examine heart, brain and retina in a group of middle-aged treated hypertensives, comparing the results with those from a group
As a consequence of heightened concern for the greenhouse effect, depleting oil reserves and skyrocketing oil prices, renewable fuels, Such as bioethanol, are becoming increasingly important. Cellulosic biomass like wood, agricultural residue and herbaceous material is a huge, cheap natural resource that can be used for ethanol production. Decreasing production costs through technological developm
Interactions between transmembrane helices play a key role in almost all cellular processes involving membrane proteins. We have investigated helix-helix interactions in lipid bilayers with synthetic tryptophan-flanked peptides that mimic the membrane spanning parts of membrane proteins. The peptides were functionalized with pyrene to allow the self-association of the helices to be monitored by py
Background: Gallstone ileus is associated with high morbidity and mortality rates. Enterolithotomy as a single procedure is recommended to minimize complications. The trauma could potentially be reduced further by using a laparoscopic technique. Methods: Thirty-two consecutive patients with gallstone ileus operated by a laparoscopic or open approach between 1992 and 2004 were studied retrospective
The capacity of regenerating nerve fibres to grow through a perforated silicon chip was tested using the silicone chamber model for nerve regeneration. The chips were fabricated as circular membranes, 4 mm in diameter, thickness 60 microns, with a perforated area, 2 mm in diameter, in the centre. Three types of chips were fabricated utilizing anisotropic etching. The chips were glued with silicone
