217 research outputs found
A Multimodal Technique for an Embedded Fingerprint Recognizer in Mobile Payment Systems
The development and the diffusion of distributed systems, directly connected to recent communication technologies, move people towards the era of mobile and ubiquitous systems. Distributed systems make merchant-customer relationships closer and more flexible, using reliable e-commerce technologies. These systems and environments need many distributed access points, for the creation and management of secure identities and for the secure recognition of users. Traditionally, these access points can be made possible by a software system with a main central server. This work proposes the study and implementation of a multimodal technique, based on biometric information, for identity management and personal ubiquitous authentication. The multimodal technique uses both fingerprint micro features (minutiae) and fingerprint macro features (singularity points) for robust user authentication. To strengthen the security level of electronic payment systems, an embedded hardware prototype has been also created: acting as self-contained sensors, it performs the entire authentication process on the same device, so that all critical information (e.g. biometric data, account transactions and cryptographic keys), are managed and stored inside the sensor, without any data transmission. The sensor has been prototyped using the Celoxica RC203E board, achieving fast execution time, low working frequency, and good recognition performance
A Novel Technique for Fingerprint Classification based on Fuzzy C-Means and Naive Bayes Classifier
Fingerprint classification is a key issue in
automatic fingerprint identification systems. One of the main
goals is to reduce the item search time within the fingerprint
database without affecting the accuracy rate. In this paper, a
novel technique, based on topological information, for
efficient fingerprint classification is described. The proposed
system is composed of two independent modules: the former
module, based on Fuzzy C-Means, extracts the best set of
training images; the latter module, based on Fuzzy C-Means
and Naive Bayes classifier, assigns a class to each processed
fingerprint using only directional image information. The
proposed approach does not require any image enhancement
phase. Experimental trials, conducted on a subset of the free
downloadable PolyU database, show a classification rate of
91% over a 100 images test database using only 12 training
examples
Moral Mediators in the Metaverse: Exploring Artificial Morality through a Talking Cricket Paradigm
As technological innovations continue to shape our social interactions, the Metaverse introduces immersive experiences that reflect real-life practices, accessible by users through their avatars. However, these interactions also bring forth potential negative aspects, including discrimination and cyberbullying. While current automatic detection systems exist, educating users on appropriate behaviour remains crucial. Leveraging recent advancements in Artificial Intelligence, the paper focuses on creating virtual AI-controlled moral agents within the Metaverse to guide users in dealing with moral dilemmas. The research aims to understand how such agents impact users' perceptions and behaviours in ethically challenging virtual environments
Time-dependent quantum transport with superconducting leads: a discrete basis Kohn-Sham formulation and propagation scheme
In this work we put forward an exact one-particle framework to study
nano-scale Josephson junctions out of equilibrium and propose a propagation
scheme to calculate the time-dependent current in response to an external
applied bias. Using a discrete basis set and Peierls phases for the
electromagnetic field we prove that the current and pairing densities in a
superconducting system of interacting electrons can be reproduced in a
non-interacting Kohn-Sham (KS) system under the influence of different Peierls
phases {\em and} of a pairing field. An extended Keldysh formalism for the
non-equilibrium Nambu-Green's function (NEGF) is then introduced to calculate
the short- and long-time response of the KS system. The equivalence between the
NEGF approach and a combination of the static and time-dependent
Bogoliubov-deGennes (BdG) equations is shown. For systems consisting of a
finite region coupled to superconducting semi-infinite leads we
numerically solve the static BdG equations with a generalized wave-guide
approach and their time-dependent version with an embedded Crank-Nicholson
scheme. To demonstrate the feasibility of the propagation scheme we study two
paradigmatic models, the single-level quantum dot and a tight-binding chain,
under dc, ac and pulse biases. We provide a time-dependent picture of single
and multiple Andreev reflections, show that Andreev bound states can be
exploited to generate a zero-bias ac current of tunable frequency, and find a
long-living resonant effect induced by microwave irradiation of appropriate
frequency.Comment: 20 pages, 9 figures, published versio
A Simple Blass Matrix Design Strategy for Multibeam Arbitrary Linear Antenna Arrays
Multibeam antenna arrays are currently recognized as one of the enabling technologies for the next-generation communication standards. One of the key components of these systems is the beamforming network (BFN) that implements the array element excitations. This article addresses this issue by presenting a novel strategy to realize an analog feeding network, which allows an arbitrary linear array (LA) to radiate multiple arbitrary beams. In particular, an iterative procedure is conceived to design a Blass matrix using an identical directional coupler for all nodes, resulting in a very simple structure suitable for large-scale production. Two applications with arbitrary directions are illustrated as proofs-of-concept for the developed architecture: a dual-beam configuration with a null involving an aperiodic LA, and a four-beam configuration involving a periodic LA. For this second application, the effectiveness of the proposed solution is further verified by full-wave simulations and experimental measurements carried out on a fabricated prototype
Role of bulk and surface phonons in the decay of metal surface states
We present a comprehensive theoretical investigation of the electron-phonon
contribution to the lifetime broadening of the surface states on Cu(111) and
Ag(111), in comparison with high-resolution photoemission results. The
calculations, including electron and phonon states of the bulk and the surface,
resolve the relative importance of the Rayleigh mode, being dominant for the
lifetime at small hole binding energies. Including the electron-electron
interaction, the theoretical results are in excellent agreement with the
measured binding energy and temperature dependent lifetime broadening.Comment: 4 pages, 3 figure
Asymptotically exact dispersion relations for collective modes in a confined charged Fermi liquid
Using general local conservations laws we derive dispersion relations for
edge modes in a slab of electron liquid confined by a symmetric potential. The
dispersion relations are exact up to , where is a wave
vector and is an effective screening length. For a harmonic external
potential the dispersion relations are expressed in terms of the {\em exact}
static pressure and dynamic shear modulus of a homogeneous liquid with the
density taken at the slab core. We also derive a simple expression for the
frequency shift of the dipole (Kohn) modes in nearly parabolic quantum dots in
a magnetic field.Comment: RevTeX4, 4 pages. Revised version with new results on quantum qots
and wires. Published in Phys.Rev.
Phospho-p38 MAPK expression in COPD patients and asthmatics and in challenged bronchial epithelium
Background: The role of mitogen-activated protein kinases (MAPK) in regulating the inflammatory response in the airways of patients with chronic obstructive pulmonary disease (COPD) and asthmatic patients is unclear. Objectives: To investigate the expression of activated MAPK in lungs of COPD patients and in bronchial biopsies of asthmatic patients and to study MAPK expression in bronchial epithelial cells in response to oxidative and inflammatory stimuli. Methods: Immunohistochemical expression of phospho (p)-p38 MAPK, p-JNK1 and p-ERK1/2 was measured in bronchial mucosa in patients with mild/moderate (n = 17), severe/very severe (n = 16) stable COPD, control smokers (n = 16), control non-smokers (n = 9), in mild asthma (n = 9) and in peripheral airways from COPD patients (n = 15) and control smokers (n = 15). Interleukin (IL)-8 and MAPK mRNA was measured in stimulated 16HBE cells. Results: No significant differences in p-p38 MAPK, p-JNK or p-ERK1/2 expression were seen in bronchial biopsies and peripheral airways between COPD and control subjects. Asthmatics showed increased submucosal p-p38 MAPK expression compared to COPD patients (p 2O2), cytomix (tumour necrosis factor-\u3b1 + IL-1\u3b2 + interferon-\u3b3) and lipopolysaccharide (LPS) upregulated IL-8 mRNA at 1 or 2 h. p38 MAPK\u3b1 mRNA was significantly increased after H2O2 and LPS treatment. JNK1 and ERK1 mRNA were unchanged after H2O2, cytomix or LPS treatments. Conclusion: p-p38 MAPK expression is similar in stable COPD and control subjects but increased in the bronchi of mild asthmatics compared to stable COPD patients. p38 MAPK mRNA is increased after bronchial epithelial challenges in vitro. These data together suggest a potential role for this MAPK in Th2 inflammation and possibly during COPD exacerbations
- …