Frequency Offset Correction in a Software Defined HiperLAN/2 Demodulator using Preamble Section A

In our Software Defined Radio project we perform a feasibility study of a software defined radio for two communication standards: HiperLAN/2 and Bluetooth. In this paper the Matlab/Simulink implementation of the HiperLAN/2 demodulator for the demonstrator of the project is discussed, with special attention for the frequency offset corrector. This type of correction is necessary to prevent large bit error rates that are caused by inter-subcarrier interference. The method that is proposed in this paper uses preamble section A to estimate the frequency offset. Simulation results for an AWGN channel show that the method is capable of correcting frequency offsets up to the boundary defined in the standard [1]. It was observed that frequency offset correction using only preamble section A is sensitive to ¿for example¿ synchronization errors in case real-life analog front-end signals are used

Alignment and theory in Corporate Real Estate alignment models

This paper deepens the understanding of Corporate Real Estate (CRE) alignment through a meta-study of twenty existing alignment models. A qualitative hermeneutic method interpreted the models and their articles. This holistic analysis found alignment to be more complex and pluralistic than the individual models assumed. Four dimensions operating simultaneously were evident – a multi-valent relationship, multiple alignment forms, multiple cognitive objects to align and alignment in multiple directions. Alignment theorisation had positive and negative aspects. Positive is that good science was evident and had improved over time. Negative is that model theorisation had occurred mostly in isolation and was constrained by simplifications required to make modelling tractable. The research makes a meta-theoretical contribution through a more complete theorisation of CRE alignment as a phenomenon. This addresses a disordered sense to prior theory thereby representing a major conceptual improvement. A new alignment model is not proposed; rather through developed understanding a basis is provided to examine alignment in both theorisation and practice

The limits of predictive remapping of attention across eye movements

With every eye movement, visual input projected onto our retina changes drastically. The fundamental question of how we keep track of relevant objects and movement targets has puzzled scientists for more than a century. Recent advances suggested that this can be accomplished through the process of predictive remapping of visual attention to the future post-saccadic locations of relevant objects. Evidence for the existence of predictive remapping of attention was first provided by Rolfs et al. (2011) (Nature Neuroscience, 14, 252-256). However, they used a single distant control location away from the task-relevant locations, which could have biased the allocation of visual attention. In this study we used a similar experimental paradigm as Rolfs et al. (2011), but probed attention equally likely at all possible locations. Our results showed that discrimination performance was higher at the remapped location than at a distant control location, but not compared to the other two control locations. A re-analysis of the results obtained by Rolfs et al. (2011) revealed a similar pattern. Together, these findings suggest that it is likely that previous reports of the predictive remapping of attention were due to a diffuse spread of attention to the task-relevant locations rather than to a specific shift toward the target's future retinotopic location

Ir. F.W. Hoeksema

Design & Implementation of digital channel selection filters for a combined BlueTooth and HiperLAN/2 receive

The Quasi-Equilibrium Longitudinal Profile in Backwater Reaches of the Engineered Alluvial River: A Space-Marching Method

An engineered alluvial river (i.e., a fixed-width channel) has constrained planform but is free to adjust channel slope and bed surface texture. These features are subject to controls: the hydrograph, sediment flux, and downstream base level. If the controls are sustained (or change slowly relative to the timescale of channel response), the channel ultimately achieves an equilibrium (or quasi-equilibrium) state. For brevity, we use the term “quasi-equilibrium” as a shorthand for both states. This quasi-equilibrium state is characterized by quasi-static and dynamic components, which define the characteristic timescale at which the dynamics of bed level average out. Although analytical models of quasi-equilibrium channel geometry in quasi-normal flow segments exist, rapid methods for determining the quasi-equilibrium geometry in backwater-dominated segments are still lacking. We show that, irrespective of its dynamics, the bed slope of a backwater or quasi-normal flow segment can be approximated as quasi-static (i.e., the static slope approximation). This approximation enables us to derive a rapid numerical space-marching solution of the quasi-static component for quasi-equilibrium channel geometry in both backwater and quasi-normal flow segments. A space-marching method means that the solution is found by stepping through space without the necessity of computing the transient phase. An additional numerical time stepping model describes the dynamic component of the quasi-equilibrium channel geometry. Tests of the two models against a backwater-Exner model confirm their validity. Our analysis validates previous studies in showing that the flow duration curve determines the quasi-static equilibrium profile, whereas the flow rate sequence governs the dynamic fluctuations.Rivers, Ports, Waterways and Dredging EngineeringEnvironmental Fluid Mechanic

Quantitative and qualitative flow cytometric analysis of nanosized cell-derived membrane vesicles

Nanosized cell-derived membrane vesicles are increasingly recognized as therapeutic vehicles and high-potential biomarkers for several diseases. Currently available methods allow bulk analysis of vesicles but are not suited for accurate quantification and fail to reveal phenotypic heterogeneity in membrane vesicle populations. For such analyses, single vesicle-based, multiparameter, high-throughput methods are needed. We developed a fluorescence-based, high-resolution flow cytometric method for quantitative and qualitative analysis of nanosized membrane vesicles. Proof of principle was obtained by single-particle analysis of virions and liposomes. Further validation was obtained by quantification of cell-derived nanosized membrane vesicles from cell cultures and body fluids. An important aspect was that the technology was extended to detect specific proteins on individual vesicles. This allowed identification of exosome subsets and phenotyping of individual exosomes produced by dendritic cells (DCs) undergoing different modes of activation. The described technology allows quantitative, multiparameter, and high-throughput analysis of a wide variety of nanosized particles and has broad applications. From the Clinical Editor: The authors developed a fluorescence-based, high-resolution flow cytometric method for quantitative and qualitative analysis of nanosized cell-derived membrane vesicles that are increasingly recognized both as therapeutic vehicles and high-potential biomarkers for several diseases. A high throughput, easily available, and sensitive detection method such as the one discussed here is a critically important prerequisite for further refinements of this technology

Quantitative and qualitative flow cytometric analysis of nanosized cell-derived membrane vesicles

Nanosized cell-derived membrane vesicles are increasingly recognized as therapeutic vehicles and high-potential biomarkers for several diseases. Currently available methods allow bulk analysis of vesicles but are not suited for accurate quantification and fail to reveal phenotypic heterogeneity in membrane vesicle populations. For such analyses, single vesicle-based, multiparameter, high-throughput methods are needed. We developed a fluorescence-based, high-resolution flow cytometric method for quantitative and qualitative analysis of nanosized membrane vesicles. Proof of principle was obtained by single-particle analysis of virions and liposomes. Further validation was obtained by quantification of cell-derived nanosized membrane vesicles from cell cultures and body fluids. An important aspect was that the technology was extended to detect specific proteins on individual vesicles. This allowed identification of exosome subsets and phenotyping of individual exosomes produced by dendritic cells (DCs) undergoing different modes of activation. The described technology allows quantitative, multiparameter, and high-throughput analysis of a wide variety of nanosized particles and has broad applications. From the Clinical Editor: The authors developed a fluorescence-based, high-resolution flow cytometric method for quantitative and qualitative analysis of nanosized cell-derived membrane vesicles that are increasingly recognized both as therapeutic vehicles and high-potential biomarkers for several diseases. A high throughput, easily available, and sensitive detection method such as the one discussed here is a critically important prerequisite for further refinements of this technology

Controlling for Biases in Primary Valuation Studies: A Meta-Analysis of International Coral Reef Values

This paper updates the existing meta-analysis in coral reef recreation taking into account the previous work of Brander et al. (2007) but considering some stated preference biases and/or effects. The present meta-analysis uses twice the number of observations as the previous one and sheds more light in understanding the influence of these common biases and/or effects found in valuations. The results show the common biases/effects in varied methodology types significantly influence the willingness to pay (WTP) estimates and in turn this has implications in welfare and benefit transfer at local, regional and global levels

Standardization of extracellular vesicle measurements by flow cytometry through vesicle diameter approximation

Essentials Platelet extracellular vesicles (EVs) concentrations measured by flow cytometers are incomparable. A model is applied to convert ambiguous scatter units to EV diameter in nanometer. Most included flow cytometers lack the sensitivity to detect EVs of 600 nm and smaller. The model outperforms polystyrene beads for comparability of platelet EV concentrations. Summary: Background Detection of extracellular vesicles (EVs) by flow cytometry has poor interlaboratory comparability, owing to differences in flow cytometer (FCM) sensitivity. Previous workshops distributed polystyrene beads to set a scatter-based diameter gate in order to improve the comparability of EV concentration measurements. However, polystyrene beads provide limited insights into the diameter of detected EVs. Objectives To evaluate gates based on the estimated diameter of EVs instead of beads. Methods A calibration bead mixture and platelet EV samples were distributed to 33 participants. Beads and a light scattering model were used to set EV diameter gates in order to measure the concentration of CD61–phycoerythrin-positive platelet EVs. Results Of the 46 evaluated FCMs, 21 FCMs detected the 600–1200-nm EV diameter gate. The 1200–3000-nm EV diameter gate was detected by 31 FCMs, with a measured EV concentration interlaboratory variability of 81% as compared with 139% with the bead diameter gate. Part of the variation in both approaches is caused by precipitation in some of the provided platelet EV samples. Flow rate calibration proved essential because systems configured to 60 μL min−1 differed six-fold in measured flow rates between instruments. Conclusions EV diameter gates improve the interlaboratory variability as compared with previous approaches. Of the evaluated FCMs, 24% could not detect 400-nm polystyrene beads, and such instruments have limited utility for EV research. Finally, considerable differences were observed in sensitivity between optically similar instruments, indicating that maintenance and training affect the sensitivity