173,270 research outputs found
A study of universal elements in classes of bases of topological spaces
No full textsummary:The universality problem focuses on finding universal spaces in classes of topological spaces. Moreover, in ``Universal spaces and mappings'' by S. D. Iliadis (2005), an important method of constructing such universal elements in classes of spaces is introduced and explained in details. Simultaneously, in ``A topological dimension greater than or equal to the classical covering dimension'' by D. N. Georgiou, A. C. Megaritis and F. Sereti (2017), new topological dimension is introduced and studied, which is called quasi covering dimension and is denoted by . In this paper, we define the base dimension-like function of the type dim, denoted by {b} - {dim}, and study the property of universality for this function. Especially, based on the method of ``Universal spaces and mappings'' by S. D. Iliadis (2005), we prove that in classes of bases which are determined by {b} - {dim} there exist universal elements
How the language we speak determines the transmission of COVID-19
No full textBackground: Little body of research has focused on the epidemic transmissibility and language interface. Aims: In this paper, we aim to investigate whether (i) the feature of aspiration found in the phonological inventory of several languages and (ii) the frequency of occurrence of stop consonants are associated with the transmission of COVID-19 among humans. Methods: The study’s protocol was based on a corpus of countries infected by COVID-19 and of which the linguistic repertoire includes a widely spoken language in individuals’ everyday communication. We tested whether languages with and without aspiration differ in terms of COVID-19 reproduction number, and whether the frequency of occurrence of stop consonants in several languages correlates with the virus reproduction number. Results: The results demonstrated no significant effect of aspiration on the transmission of the virus, while a positive correlation between the frequency of occurrence and transmissibility was observed only for the consonant /p/; this might suggest that languages that use /p/ more frequently might spread the virus more easily. Conclusions: The findings of this study can offer a tentative picture of how speaking specific sounds can be associated with COVID-19 transmissibility. © 2021, Royal Academy of Medicine in Ireland
On fuzzy theta-convergences
No full textIn this paper we introduce and study the notions of fuzzy theta -convergence and weakly theta -convergence on a fuzzy topological space. These notions can be considered as generalizations of the convergence defined in Georgiou and Papadopoulos (1998). Also the forementioned theta -convergence does not coincide with the one defined in Chen and Chenn (1997). The importance of these convergences relies on the fact that they behave equally well as the convergence defined in Georgiou and Papadopoulos (1998). (C) 2000 Elsevier Science B.V. All rights reserved
Effect of mobile ionic-charge on CMOS based ion-sensitive field-effect transistors (ISFETs)
No full textThis work is an investigation on the large threshold voltage variation exhibited in CMOS based ISFETs. This irregularity is thoroughly examined and is identified to be caused by mobile ionic charge that is induced in the sensing membrane when the membrane is in contact with the ionic-solution. This auxiliary charge increments the effective capacitance of the sensing membrane, causing irregular shifts in the characteristics of the devices. Several methods for overcoming this issue are addressed
An Extended CMOS ISFET Model Incorporating the Physical Design Geometry and the Effects on Performance and Offset Variation
No full text17/04/13 meb. Accepted version OK to pub.This paper presents an extended model for the
CMOS-based Ion-Sensitive-Field-Effect-Transistor (ISFET), incorporating design parameters associated with the physical
geometry of the device. This can, for the first time, provide a good match between calculated and measured characteristics by
taking into account the effects of non-idealities such as threshold voltage variation and sensor noise. The model is evaluated through a number of devices with varying design parameters (chemical sensing area and MOSFET dimensions) fabricated in
a commercially-available 0.35μm CMOS technology. Threshold voltage, subthreshold slope, chemical sensitivity, drift and noise
were measured and compared to the simulated results. The first and second order effects are analysed in detail and it is shown that the sensors’ performance was in agreement with the proposed model
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Random geometric graphs with general connection functions
No full textSpatially Embedded Networks is an EPSRC funded project, EP/N002458/1, linked to a project in Oxford EP/N002350/1. It involves exploring mathematical and network properties random graphs in which the nodes are located in space, with application to wireless communications. These data files are for Figs 4-6 of the paper "Random geometric graphs with general connection functions" C. P. Dettmann and O. Georgiou
Robustness in the graph topology of a common adaptive controller
No full textFor any m-input, m-output, finite-dimensional, linear, minimum-phase plant P with first Markov parameter having spectrum in the open right-half complex plane, it is well known that the adaptive output feedback control C, given by u = -ky, k = ||y||2, yields a closed-loop system [P,C] for which the state converges to zero, the signal k converges to a finite limit, and all other signals are of class L2. It is first shown that these properties continue to hold in the presence of L2-input and L2-output disturbances. By establishing gain function stability of an appropriate closed-loop operator, it is proved that these properties also persist when the plant P is replaced by a stabilizable and detectable linear plant P1 within a sufficiently small neighbourhood of P in the graph topology, provided that the plant initial data and the L2 magnitude of the disturbances are sufficiently small. Example 9 of Georgiou & Smith (IEEE Trans. Autom. Control 42(9) 1200-1221, 1997) is revisited to which the above L2-robustness result applies. Unstable behaviour for large initial conditions and/or large L2 disturbances is shown, demonstrating that the bounds obtained from the L2 theory are qualitatively tight: this contrasts with the L∞-robustness analysis of Georgiou & Smith which is insufficiently tight to predict the stable behaviour for small initial conditions and zero disturbances
1-pass fixed-rate linear resampler in Matlab/Octave
No full text<p>DESCRIPTION:</p>
<p>This is a template stand-alone code (no externals required) for a simple 1-pass fixed rate linear resampler. Specifically, the script can be used as-is or as base for a function, which take a series of pairs <t,x> and a requested fixed resampling rate and it produces a new series of <t',x'> using stepwise linear regressors.</p>
<p>The script includes a data sorting step against <t>, which is not implemented here internally and can be removed if the input data are already expected to be sorted. In case of no sorting step here, the script is completely 1-pass, which means that all elements of the two input vectors (ref. points) are read only once for the entire resampling process. This is particularly useful when this implementation is to be applied directly to extremely large input files (e.g. columns in .csv) with only minimal memory usage for the calculations and only sequential read mode for speed.</p>
<p>Note: This work is supported by the DART project (H2020): "Data-Driven Aircraft Trajectory Prediction Research" (http://dart-research.eu) and the Data Science Lab (http://www.datastories.org) at the University of Piraeus, Greece (http://www.unipi.gr).</p>AUTHOR: Harris Georgiou (MSc,PhD) - IS/IT Engineer (R&D)
COPYRIGHT: Data Science Lab @ UniPi (c) 2017 - http://www.datastories.org
LICENCE: Creative Commons (CC-BY-SA) 4.0/I - http://creativecommons.or
Methotrexate-induced bone marrow adiposity Is mitigated by folinic acid supplementation through the regulation of Wnt/beta-catenin signalling
No full textAccepted manuscript online in Wiley Online Library (wileyonlinelibrary.com): 4 September 2014.Abstract not availableKristen R. Georgiou, Rethi Raghu Nadhanan, Chia-Ming Fan, and Cory J. Xia
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