Design issues and experimental characterization of a continuously-tuned adaptive CMOS LNA

This paper presents the design implementation and experimental characterization of an adaptive Low Noise Amplifier (LNA) intended for multi-standard Radio Frequency (RF) wireless transceivers. The circuit —fabricated in a 90-nm CMOS technology— is a two-stage inductively degenerated common-source topology that combines PMOS varactors with programmable load to make the operation of the circuit continuously tunable. Practical design issues are analyzed, considering the effect of circuit parasitics associated to the chip package and integrated inductors, capacitors and varactors. Experimental measurements show a continuous tuning of NF and Sparameters within the 1.75-2.23GHz band, featuring NF19.6dB and IIP3> −9.8dBm, with a power dissipation < 23mW from a 1-V supply voltage.Ministerio de Ciencia e Innovación (FEDER) TEC2007-67247-C02-01/MICJunta de Andalucía, Consejo Regional de Innovación, ciencia y empresa TIC-253

Efecto de caucho reciclado en las propiedades de mezclas de caucho reciclado y polipropileno reciclado

This study evaluates the influence of recycled rubber (RR) with a specific particle size in the properties of blends, blended recycled polypropylene/polyethylene (RPP) and RR (RPP/RR) -- The proportions of RPP/RR employed to obtain the blends were as follows: 90/10 (PP90), 75/25 (PP75), 60/40 (PP60) and 45/55 (PP45) -- The particle size of the RR employed was 850 µm -- The properties of the blends were evaluated by rheometric, thermogravimetric (TGA), differential scanning calorimetric (DSC), scanning electronic microscopy (SEM), density, melt flow index and tensile analysis -- The maximum torque increased with the RPP content -- By DSC analysis, it was observed that the RPP exhibited two melting temperatures, the first corresponded to low density polyethylene (LDPE) and the second to polypropylene (PP) -- Furthermore, the RR affected the crystallinity of the RPP -- By using SEM and TGA analyses, it was determined that the RPP as well as RR contained fillers -- The blend densities were higher than those of RPP -- The melt flow index exhibited a trend with the amount of RR.PACS: 61.25.hk, 83.80.Va, 81.05.LgEste estudio evalúa la influencia de caucho reciclado (RR) con un tamaño de partícula específico en las propiedades de mezclas, mezclas de polipropileno reciclado/polietileno (RPP) y RR (RPP/RR) -- Las proporciones de RPP/RR para obtener los compósitos fueron como sigue: 90/10 (PP90), 75/25 (PP75), 60/40 (PP60) and 45/55 (PP45) -- El tamaño de partícula empleado del RR fue 850 µm -- Las propiedades de las mezclas, fueron evaluadas por análisis reométrico, termogravimétrico (TGA), calorimetría diferencial de barrido (DSC), microscopia de barrido electrónica (SEM), densidad, índice de fluidez y ténsil -- El torque máximo incrementó con el contenido de RPP -- Por análisis DSC se observó que el RPP exhibió dos temperaturas de fusión, la primera correspondió al polietileno de baja densidad (LDPE) y la segunda al polipropileno (PP) -- Además, el RR afectó la cristalinidad del RPP -- Por análisis de SEM y TGA, se determinó que el RR y el RPP contenían rellenos -- Las densidades de las mezclas fueron más altas que la del RPP -- El índice de fluidez exhibió una tendencia con la cantidad de RR.PACS: 61.25.hk, 83.80.Va, 81.05.L

The mutual information between graphs

The estimation of mutual information between graphs has been an elusive problem until the formulation of graph matching in terms of manifold alignment. Then, graphs are mapped to multi-dimensional sets of points through structure preserving embeddings. Point-wise alignment algorithms can be exploited in this context to re-cast graph matching in terms of point matching. Methods based on bypass entropy estimation must be deployed to render the estimation of mutual information computationally tractable. In this paper the novel contribution is to show how manifold alignment can be combined with copula-based entropy estimators to efficiently estimate the mutual information between graphs. We compare the empirical copula with an Archimedean copula (the independent one) in terms of retrieval/recall after graph comparison. Our experiments show that mutual information built in both choices improves significantly state-of-the art divergences.Funding. F. Escolano, M.A. Lozano: Project TIN2012-32839 (Spanish Gov.). M. Curado: BES-2013-064482 (Spanish Gov.). E. R. Hancock: Royal Society Wolfson Research Merit Award

Early Detection of Alzheimer’s Disease : Detecting Asymmetries with a Return Random Walk Link Predictor

Alzheimer’s disease has been extensively studied using undirected graphs to represent the correlations of BOLD signals in different anatomical regions through functional magnetic resonance imaging (fMRI). However, there has been relatively little analysis of this kind of data using directed graphs, which potentially offer the potential to capture asymmetries in the interactions between different anatomical brain regions. The detection of these asymmetries is relevant to detect the disease in an early stage. For this reason, in this paper, we analyze data extracted from fMRI images using the net4Lap algorithm to infer a directed graph from the available BOLD signals, and then seek to determine asymmetries between the left and right hemispheres of the brain using a directed version of the Return Random Walk (RRW). Experimental evaluation of this method reveals that it leads to the identification of anatomical brain regions known to be implicated in the early development of Alzheimer’s disease in clinical studies

Dirichlet Densifier Bounds : Densifying Beyond the Spectral Gap Constraint

In this paper, we characterize the universal bounds of our recently reported Dirichlet Densifier. In particular we aim to study the impact of densification on the bounding of intra-class node similarities. To this end we derive a new bound for commute time estimation. This bound does not rely on the spectral gap, but on graph densification (or graph rewiring). Firstly, we explain how our densifier works and we motivate the bound by showing that implicitly constraining the spectral gap through graph densification cannot fully explain the cluster structure in real-world datasets. Then, we pose our hypothesis about densification: a graph densifier can only deal with a moderate degradation of the spectral gap if the inter-cluster commute distances are significantly shrunk. This points to a more detailed bound which explicitly accounts for the shrinking effect of densification. Finally, we formally develop this bound, thus revealing the deeper implications of graph densification in commute time estimation

Dirichlet Densifiers for Improved Commute Times Estimation

In this paper, we develop a novel Dirichlet densifier that can be used to increase the edge density in undirected graphs. Dirichlet densifiers are implicit minimizers of the spectral gap for the Laplacian spectrum of a graph. One consequence of this property is that they can be used improve the estimation of meaningful commute distances for mid-size graphs by means of topological modifications of the original graphs. This results in a better performance in clustering and ranking. To do this, we identify the strongest edges and from them construct the so called line graph, where the nodes are the potential q −step reachable edges in the original graph. These strongest edges are assumed to be stable. By simulating random walks on the line graph, we identify potential new edges in the original graph. This approach is fully unsupervised and it is both more scalable and robust than recent explicit spectral methods, such as the Semi-Definite Programming (SDP) densifier and the sufficient condition for decreasing the spectral gap. Experiments show that our method is only outperformed by some choices of the parameters of a related method, the anchor graph, which relies on pre-computing clusters representatives, and that the proposed method is effective on a variety of real-world datasets.M. Curado, F. Escolano and M.A. Lozano are funded by the projects TIN2015-69077-P and BES2013-064482 of the Spanish Government