Endothelial cell-matrix interactions

Dynamic interactions between endothelial cells and components of their surrounding extracellular matrix are necessary for the invasion, migration, and survival of endothelial cells during angiogenesis. These interactions are mediated by matrix receptors that initiate intracellular signaling cascades in response to binding to specific extracellular matrix molecules. The interactions between endothelial cells and their environment are also modulated by enzymes that degrade different matrix components and thus enable endothelial invasion. Recent reports on gene targeting in mice have confirmed the role of two classes of matrix receptors, integrins and cell surface heparan sulfate proteoglycans, and a group of matrix degrading proteolytic enzymes, matrix metalloproteinases, in angiogenesis. The significance of endothelial cell-matrix interactions is further supported by several ongoing clinical trials that analyze the effects of drugs blocking this interaction on angiogenesis-dependent growth of human tumors.     

Light scattering by wood fibers

We consider the scattering of light by single wood fibers both theoretically and experimentally. We describe the size and the shape distributions and the internal structure and chemical composition of the wood fibers. We have modeled the random shape of the hollow, cylindrical wood fiber by using multivariate lognormal statistics. We have computed wood-fiber absorption and scattering cross sections, asymmetry parameters, and scattering phase matrices in the ray-optics approximation. Finally, we have provided experimental results from angular scattering measurements for wood fibers and present what we believe is the first comparison between these measurements and ray-optics computations for Gaussian random wood-fiber models. In spite of the complicated internal structure of the wood fiber, our model together with the ray-optics treatment explains the scattering measurements surprisingly well.     

Pricing based adaptive scheduling method for bandwidth allocation

In this paper we present a packet scheduling method which guarantees bandwidth of the connection and optimizes revenue of the network service provider. A closed form formula for updating the adaptive weights of a packet scheduler is derived from a revenue-based optimization problem. The weight updating procedure is fast and independent on the assumption of the connections’ statistical behavior. The features of the algorithm are simulated and analyzed with and without a call admission control (CAC) mechanism. We also show in context with the CAC procedure a mechanism for guaranteeing a specified mean bandwidth for different service classes.     

Measuring the Size Distribution of Atmospheric Organic and Black Carbon Using Impactor Sampling Coupled with Thermal Carbon Analysis: Method Development and Uncertainties

A method for determining the mass size distribution of organic and black carbon (OC and BC) in atmospheric aerosols is introduced. The method relies on a particle sampling with 2 parallel size-segregating devices, a 12-stage Small Deposit area low pressure impactor (SDI) and a virtual impactor (VI), and the subsequent analysis of the samples with thermal and thermal-optical methods, respectively. The method development revealed that SDI is, like other sampling methods, susceptible to serious sampling artifacts and OC pyrolysis during thermal analysis. However, some of the SDI's limitations can be overcome by parallel VI measurements. The good correlation between the SDI and the VI data for most of the samples collected here indicates that under most conditions, the lack of the pyrolysis correction for the SDI samples does not cause significant errors in the OC/BC split. Valuable features of this method are that it offers a good size resolution in both sub- and supermicron size fractions, indicates if there has been serious positive or negative artifacts for OC during sampling, reveals if the samples have been affected by OC pyrolysis during thermal analysis, and provides semiquantitative means by which the OC and BC size distributions can be corrected for the samples being affected by OC pyrolysis. Application of the method to real atmospheric samples is demonstrated, and the major areas requiring further research and/or method development are identified.     

Two-tier relaxed heaps

We introduce a data structure which provides efficient heap operations with respect to the number of element comparisons performed. Let n denote the size of the heap being manipulated. Our data structure guarantees the worst-case cost of O(1) for finding the minimum, inserting an element, extracting an (unspecified) element, and replacing an element with a smaller element; and the worst-case cost of O(lg n) with at most lg n + 3 lg lg n + O(1) element comparisons for deleting an element. We thereby improve the comparison complexity of heap operations known for run-relaxed heaps and other worst-case efficient heaps. Furthermore, our data structure supports melding of two heaps of size m and n at the worst-case cost of O(min {lg m, lg n}). A preliminary version of this paper [8] was presented at the 17th International Symposium on Algorithms and Computation held in Kolkata in December 2006. Partially supported by the Danish Natural Science Research Council under contracts 21-02-0501 (project Practical data structures and algorithms) and 272-05-0272 (project Generic programming—algorithms and tools).     

What goes down must come up? Trends of industrial electricity use in the North-West of Russia

This article uses decomposition method to analyse industrial electricity consumption in North-Western Russia, namely in Archangelsk oblast, the Republic of Karelia and Murmansk oblast. The case sectors, forestry and electricity, have in most cases developed similarly in the chosen regions during 1990–2001. The decomposition analysis shows that the reduction of economic activity has reduced electricity consumption in all three regions but that it is not always the main factor reducing consumption. The changes in energy efficiency increased consumption in the forestry sector in all regions while in the electricity sector it led to a reduction. The changes in the structures of the regional economies increased electricity consumption in electricity industry which gained importance due to developments in the manufacturing industry. In Murmansk, forestry sector has almost disappeared during the observation period. This was the main observed electricity consumption reduction caused by structural changes. Many of the developments can be better understood against the general knowledge of transition factors.     

Impact of heat load location and strength on air flow pattern with a passive chilled beam system

A passive chilled beam is a source of natural convection, creating a flow of cold air directly into the occupied zone. Experiments were conducted in a mock-up of an office room to study the air velocities in the occupied spaces. In addition, velocity profiles are registered when underneath heat loads exist and the cool and warm air flows interact. Experimental laboratory study revealed that in the case of the underneath heat gains, even no upward plume was generated and the dummy only acted as a flow obstacle, having a significant effect on the velocity profile. Furthermore, in an actual occupied office environment, the thermal plumes and the supply air diffuser mixed effectively the whole air volume. The maximum air velocity measured was still below 0.25 m/s with the extremely high heat gain of 164 W/m². The results demonstrate that analysis methods were the interaction of convection flow and jet are not taken into account could not accurately describe air movement and draught risk in the occupied room space.     

Sensor validation using minimum mean square error estimation

Sensor fault can be detected and corrected in a multichannel measurement system with enough redundancy using solely the measurement data. A single or multiple sensors can be estimated from the remaining sensors if training data from the functioning sensor network are available. The method is based on the minimum mean square error (MMSE) estimation, which is applied to the time history data, e.g. accelerations. The faulty sensor can be identified and replaced with the estimated sensor. Both spatial and temporal correlation of the sensors can be utilized. Using the temporal correlation is justified if the number of active structural modes is larger than the number of sensors. The disadvantages of the temporal model are discussed. Experimental multichannel vibration measurements are used to verify the proposed method. Different, and also simultaneous, sensor faults are studied. The effects of environmental variability and structural damage are discussed.