13,251 research outputs found
Modelling prevention strategies in Public Health
Various schemes of prevention measures in public health are developed and analyzed on the basis of a general mathematical model. Features related to cost issues,
including primary and secondary prevention interventions, differential survival experiences and communicable diseases are in turn used to show the potentialities of
the theoretical framework. Statistical estimation procedures are briefly discussed and a numerical application is presented with reference to Italian cancer data
Tomographic map within the framework of star-product quantization
Tomograms introduced for the description of quantum states in terms of
probability distributions are shown to be related to a standard star-product
quantization with appropriate kernels. Examples of symplectic tomograms and
spin tomograms are presented.Comment: LATEX plus sprocl.sty, to appear in the Proceedings of the conference
``Quantum Theory and Symmetries'' (Krakow, July 2001), World Scietifi
A Semantic Web Annotation Tool for a Web-Based Audio Sequencer
Music and sound have a rich semantic structure which is so clear to the composer and the listener, but that remains mostly hidden to computing machinery. Nevertheless, in recent years, the introduction of software tools for music production have enabled new opportunities for migrating this knowledge from humans to machines. A new generation of these tools may exploit sound samples and semantic information coupling for the creation not only of a musical, but also of a "semantic" composition. In this paper we describe an ontology driven content annotation framework for a web-based audio editing tool. In a supervised approach, during the editing process, the graphical web interface allows the user to annotate any part of the composition with concepts from publicly available ontologies. As a test case, we developed a collaborative web-based audio sequencer that provides users with the functionality to remix the audio samples from the Freesound website and subsequently annotate them. The annotation tool can load any ontology and thus gives users the opportunity to augment the work with annotations on the structure of the composition, the musical materials, and the creator's reasoning and intentions. We believe this approach will provide several novel ways to make not only the final audio product, but also the creative process, first class citizens of the Semantic We
No Place to Hide that Bytes won't Reveal: Sniffing Location-Based Encrypted Traffic to Track a User's Position
News reports of the last few years indicated that several intelligence
agencies are able to monitor large networks or entire portions of the Internet
backbone. Such a powerful adversary has only recently been considered by the
academic literature. In this paper, we propose a new adversary model for
Location Based Services (LBSs). The model takes into account an unauthorized
third party, different from the LBS provider itself, that wants to infer the
location and monitor the movements of a LBS user. We show that such an
adversary can extrapolate the position of a target user by just analyzing the
size and the timing of the encrypted traffic exchanged between that user and
the LBS provider. We performed a thorough analysis of a widely deployed
location based app that comes pre-installed with many Android devices:
GoogleNow. The results are encouraging and highlight the importance of devising
more effective countermeasures against powerful adversaries to preserve the
privacy of LBS users.Comment: 14 pages, 9th International Conference on Network and System Security
(NSS 2015
Decay-less kink oscillations in coronal loops
Context: Kink oscillations of coronal loops in an off-limb active region are detected with the Imaging Assembly Array (AIA) instruments of the Solar Dynamics Observatory (SDO) at 171 Å.
Aims: We aim to measure periods and amplitudes of kink oscillations of different loops and to determinate the evolution of the oscillation phase along the oscillating loop.
Methods: Oscillating coronal loops were visually identified in the field of view of SDO/AIA and STEREO/EUVI-A: the loop length was derived by three-dimensional analysis. Several slits were taken along the loops to assemble time-distance maps. We identified oscillatory patterns and retrieved periods and amplitudes of the oscillations. We applied the cross-correlation technique to estimate the phase shift between oscillations at different segments of oscillating loops.
Results: We found that all analysed loops show low-amplitude undamped transverse oscillations. Oscillation periods of loops in the same active region range from 2.5 to 11 min, and are different for different loops. The displacement amplitude is lower than 1 Mm. The oscillation phase is constant along each analysed loop. The spatial structure of the phase of the oscillations corresponds to the fundamental standing kink mode. We conclude that the observed behaviour is consistent with the empirical model in terms of a damped harmonic resonator affected by a non-resonant continuously operating external force
A conformal field theory description of the paired and parafermionic states in the quantum Hall effect
We extend the construction of the effective conformal field theory for the
Jain hierarchical fillings proposed in cond-mat/9912287 to the description of a
quantum Hall fluid at non standard fillings nu=m/(pm+2). The chiral primary
fields are found by using a procedure which induces twisted boundary conditions
on the m scalar fields; they appear as composite operators of a charged and
neutral component. The neutral modes describe parafermions and contribute to
the ground state wave function with a generalized Pfaffian term. Correlators of
Ne electrons in the presence of quasi-hole excitations are explicitly given for
m=2.Comment: 11 pages, plain Late
Phase Transitions in Gauge Models: Towards Quantum Simulations of the Schwinger-Weyl QED
We study the ground-state properties of a class of lattice
gauge theories in 1 + 1 dimensions, in which the gauge fields are coupled to
spinless fermionic matter. These models, stemming from discrete representations
of the Weyl commutator for the group, preserve the unitary
character of the minimal coupling, and have therefore the property of formally
approximating lattice quantum electrodynamics in one spatial dimension in the
large- limit. The numerical study of such approximated theories is important
to determine their effectiveness in reproducing the main features and
phenomenology of the target theory, in view of implementations of cold-atom
quantum simulators of QED. In this paper we study the cases by
means of a DMRG code that exactly implements Gauss' law. We perform a careful
scaling analysis, and show that, in absence of a background field, all
models exhibit a phase transition which falls in the Ising
universality class, with spontaneous symmetry breaking of the symmetry. We
then perform the large- limit and find that the asymptotic values of the
critical parameters approach the ones obtained for the known phase transition
the zero-charge sector of the massive Schwinger model, which occurs at negative
mass.Comment: 15 pages, 18 figure
Asymmetric Architecture for Heralded Single Photon Sources
Single photon source represent a fundamental building block for optical
implementations of quantum information tasks ranging from basic tests of
quantum physics to quantum communication and high-resolution quantum
measurement. In this paper we investigate the performance of a multiplexed
system based on asymmetric configuration of multiple heralded single photon
sources. {To compare the effectiveness of different designs we introduce a
single-photon source performance index that is based on the value of single
photon probability required to achieve a guaranteed signal to noise ratio.} The
performance and scalability comparison with both currently existing
multiple-source architectures and faint laser configurations reveals an
advantage the proposed scheme offers in realistic scenarios. This analysis also
provides insights on the potential of using such architectures for integrated
implementation.Comment: 11 pages, 13 figure
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