A Porous Structure of Nanofiber Electrospun Polyacrylonitrile-Based Materials: a Standard Contact Porosimetry Study

Protection of Metals and Physical Chemistry of Surfaces - The formation regularities and quantitative porosity characteristics of nanofibrous electrospun composite materials based on...     

A new similarity measure for non-local means filtering of MRI images

In this paper, the application of non-local means (NLM) filtering on MRI images is investigated. An essential component of any NLM-based algorithm is its similarity measure used to compare pixel intensities. Unfortunately, virtually all existing similarity measures used to denoise MRI images have been derived under the assumption of additive white Gaussian noise contamination. Since this assumption is known to fail at low values of signal-to-noise ratio (SNR), alternative formulations of these measures which take into account the correct (Rician) statistics of the noise are required. Accordingly, the main contribution of the present work is to introduce a new similarity measure for NLM filtering of MRI images, which is derived under bona fide statistical assumptions and proves to posses important theoretical advantages over alternative formulations. The utility and viability of the proposed method is demonstrated through a series of numerical experiments using both in silico and in vivo MRI data.     

Fuzzy characterization of spike synchrony in parallel spike trains

We present a framework for characterizing spike (and spike-train) synchrony in parallel neuronal spike trains that is based on the identification of spikes with what we call influence maps: real-valued functions that describe an influence region around the corresponding spike times within which possibly graded (i.e., fuzzy) synchrony with other spikes is defined. We formalize two models of synchrony in this framework: the bin-based model (the almost exclusively applied model in the field) and a novel, alternative model based on a continuous, graded notion of synchrony, aimed at overcoming the drawbacks of the bin-based model. We study the task of identifying frequent (and synchronous) neuronal patterns from parallel spike trains in our framework, formalized as an instance of what we call the fuzzy frequent pattern mining problem (a generalization of standard frequent pattern mining) and briefly evaluate our synchrony models on this task.     

Validation of Grid Middleware for the European Grid Infrastructure

The European Grid Infrastructure (EGI) is providing a sustainable pan–European Computing Grid to support e–Science, integrating more than 350 computing resource centers worldwide. One of its main challenges is that the middleware driving this production infrastructure is constantly evolving, as it adapts to the changing needs of the EGI Community. Since the software is provided by external technology providers, it needs to pass through a quality verification process before it is included in the EGI official release called Unified Middleware Distribution (UMD). Therefore, all software components undergo a release process covering the definition of the functionality and quality criteria, the verification of those criteria, and the testing under production environments. This paper details the design, development and implementation of this software validation process. An analysis is performed on several metrics to evaluate the process impact on the stability of the production infrastructure, by capturing malfunctions and other issues at the initial testing phases.     

A General Purpose Configurable Controller for Indoors and Outdoors GPS-Denied Navigation for Multirotor Unmanned Aerial Vehicles

This research on odometry based GPS-denied navigation on multirotor Unmanned Aerial Vehicles is focused among the interactions between the odometry sensors and the navigation controller. More precisely, we present a controller architecture that allows to specify a speed specified flight envelope where the quality of the odometry measurements is guaranteed. The controller utilizes a simple point mass kinematic model, described by a set of configurable parameters, to generate a complying speed plan. For experimental testing, we have used down-facing camera optical-flow as odometry measurement. This work is a continuation of prior research to outdoors environments using an AR Drone 2.0 vehicle, as it provides reliable optical flow on a wide range of flying conditions and floor textures. Our experiments show that the architecture is realiable for outdoors flight on altitudes lower than 9 m. A prior version of our code was utilized to compete in the International Micro Air Vehicle Conference and Flight Competition IMAV 2012. The code will be released as an open-source ROS stack hosted on GitHub.     

Segmental localization and quantitative characteristics of tubulitis in kidney biopsies from patients undergoing acute rejection

The term tubulitis denotes infiltration of the renal tubular epithelium by mononuclear cells. Tubulitis is one of the most reliable signs of acute renal allograft rejection. However, its segmental localization and quantitative characteristics are not precisely known. To investigate this question, formalin-fixed kidney biopsy specimens from 15 patients with transplanted allografts undergoing acute rejection were studied stereologically by identifying cortical tubules with segment-specific markers. The periodic acid-Schiff reaction, peanut lectin, and antibodies against Tamm-Horsfall protein and epidermal cytokeratins, all applied to the same section, were used to identify the profiles of proximal tubules (PTs), distal convoluted tubules (DCTs), distal straight tubules (DSTs), and the cortical collecting system (CCS, connecting tubules and cortical collecting ducts), respectively. Two parameters, the relative intrasegmental length and the average intensity of tubular damage, were determined to describe the degree of tubulitis quantitatively. Tubulitis was most prominent in the DCTs, followed by the CCS. The average intensity of tubulitis was lowest in the DSTs. The results indicate that the PTs are not the main site of tubulitis, despite the fact that they are regarded primary targets of the rejection response.     

Rapid microanalytical chlorine determination in polymers by ion selective electrode

A rapid microanalytical method has been developed for the determination of very small amounts of chlorine in polymers. The gist of the method comprises quantitative dechlorination by sodium biphenyl or dehydrochlorination bytert-BuOK, aqueous extraction of the Cl^? formed, followed by [Cl^?] quantitation by chloride ion selective electrode (CSE). The method has been tested and is now used routinely for chlorine end group quantitation of telechelic polyisobutylene (PIB), poly(2,4,6-trimethylstyrene) (PTMSt), and poly(p-chlorostyrene) (PpClSt).