240 research outputs found
Efficient Sum-of-Sinusoids based Spatial Consistency for the 3GPP New-Radio Channel Model
Spatial consistency was proposed in the 3GPP TR 38.901 channel model to
ensure that closely spaced mobile terminals have similar channels. Future
extensions of this model might incorporate mobility at both ends of the link.
This requires that all random variables in the model must be correlated in 3
(single-mobility) and up to 6 spatial dimensions (dual-mobility). Existing
filtering methods cannot be used due to the large requirements of memory and
computing time. The sum-of-sinusoids model promises to be an efficient
solution. To use it in the 3GPP channel model, we extended the existing model
to a higher number of spatial dimensions and propose a new method to calculate
the sinusoid coefficients in order to control the shape of the autocorrelation
function. The proposed method shows good results for 2, 3, and 6 dimensions and
achieves a four times better approximation accuracy compared to the existing
model. This provides a very efficient implementation of the 3GPP proposal and
enables the simulation of many communication scenarios that were thought to be
impossible to realize with geometry-based stochastic channel models
Phagocytosis and Phagosomal Fate of Surface-Modified Microparticles in Dendritic Cells and Macrophages
Purpose. We compared cationic, polyamine-coated microparticles (MPs) and anionic, protein-coated MPs with respect to their phagocytosis and phagosomal fate in dendritic cells (DCs) and macrophages (MĪ¦). Methods. Polystyrene MPs were surface modified by covalent coupling with fluorescein isothiocyanate-labeled polyamines or proteins. Phagocytosis of MP and the pH of their intracellular microenvironment was assessed in human-derived DCs and MĪ¦ in a fluorescence plate reader. Visualization of MP phagocytosis in DCs was performed by transmission electron microscopy. Results. Phagocytosis of bovine serum albumin-coated MPs was low with significant differences between DC and MĪ¦, whereas phagocytosis of IgG-coated MPs was significantly enhanced in both cell types. Phagocytosis of both particle types resulted in an acidified phagosomal microenvironment (pH 4.6-5.1). In contrast, cationic, polyamine-coated MPs were equally phagocytosed by DCs and MĪ¦ to a high extent and showed lower degrees of acidification (pH 6.0-6.8) in the phagosomal microenvironment. Transmission electron microscopy examination demonstrated all phagocytosed particles to be surrounded by a phagosomal membrane, which was more tightly apposed to the surface of cationic MPs and more loosely to bovine serum albumin-coated MPs. Conclusion. Phagocytosis of cationic, polyamine-coated MPs is suggested to lead to diminished phagosomal acidification. Thus, cationic MP are potential carriers that may display beneficial features for the intracellular delivery of immunomodulating therapeutics and their protection against lysosomal degradatio
DeExcelerator: A Framework for Extracting Relational Data From Partially Structured Documents
Of the structured data published on the web, for instance as datasets on Open Data Platforms such as data.gov, but also in the form of HTML tables on the general web, only a small part is in a relational form. Instead the data is intermingled with formatting, layout and textual metadata, i.e., it is contained in partially structured documents. This makes transformation into a true relational form necessary, which is a precondition for most forms of data analysis and data integration. Studying data.gov as an example source for partially structured documents, we present a classification of typical normalization problems. We then present the DeExcelerator, which is a framework for extracting relations from partially structured documents such as spreadsheets and HTML tables
Efficient Worst-Case Temperature Evaluation for Thermal-Aware Assignment of Real-Time Applications on MPSoCs
The reliability of multiprocessor system-on-chips (MPSoCs) is nowadays threatened by high chip temperatures leading to long-term reliability concerns and short-term functional errors. High chip temperatures might not only cause potential deadline violations, but also increase cooling costs and leakage power. Pro-active thermal-aware allocation and scheduling techniques that avoid thermal emergencies are promising techniques to reduce the peak temperature of an MPSoC. However, calculating the peak temperature of hundreds of design alternatives during design space exploration is time-consuming, in particular for unknown input patterns and data. In this paper, we address this challenge and present a fast analytic method to calculate a non-trivial upper bound on the maximum temperature of a multi-core real-time system with non-deterministic workload. The considered thermal model is able to address various thermal effects like heat exchange between neighboring cores and temperature-dependent leakage power. Afterwards, we integrate the proposed thermal analysis method into a design-space exploration framework to optimize the task to processing component assignment. Finally, we apply the proposed method in various case studies to explore thermal hot spots and to optimize the task to processing component assignmen
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