4,029 research outputs found
Pettis integrability of fuzzy mappings with values in arbitrary Banach spaces
In this paper we study the Pettis integral of fuzzy mappings in arbitrary
Banach spaces. We present some properties of the Pettis integral of fuzzy
mappings and we give conditions under which a scalarly integrable fuzzy mapping
is Pettis integrable
Impact of classical forces and decoherence in multi-terminal Aharonov-Bohm networks
Multi-terminal Aharonov-Bohm (AB) rings are ideal building blocks for quantum
networks (QNs) thanks to their ability to map input states into controlled
coherent superpositions of output states. We report on experiments performed on
three-terminal GaAs/Al_(x)Ga_(1-x)As AB devices and compare our results with a
scattering-matrix model including Lorentz forces and decoherence. Our devices
were studied as a function of external magnetic field (B) and gate voltage at
temperatures down to 350 mK. The total output current from two terminals while
applying a small bias to the third lead was found to be symmetric with respect
to B with AB oscillations showing abrupt phase jumps between 0 and pi at
different values of gate voltage and at low magnetic fields, reminiscent of the
phase-rigidity constraint due to Onsager-Casimir relations. Individual outputs
show quasi-linear dependence of the oscillation phase on the external electric
field. We emphasize that a simple scattering-matrix approach can not model the
observed behavior and propose an improved description that can fully describe
the observed phenomena. Furthermore, we shall show that our model can be
successfully exploited to determine the range of experimental parameters that
guarantee a minimum oscillation visibility, given the geometry and coherence
length of a QN.Comment: 7 pages, 8 figure
Nonlinear double Compton scattering in the full quantum regime
A detailed analysis of the process of two photon emission by an electron
scattered from a high-intensity laser pulse is presented. The calculations are
performed in the framework of strong-field QED and include exactly the presence
of the laser field, described as a plane wave. We investigate the full quantum
regime of interaction, where photon recoil plays an essential role in the
emission process, and substantially alters the emitted photon spectra as
compared to those in previously-studied regimes. We provide a semiclassical
explanation for such differences, based on the possibility of assigning a
trajectory to the electron in the laser field before and after each quantum
photon emission. Our numerical results indicate the feasibility of
investigating experimentally the full quantum regime of nonlinear double
Compton scattering with already available plasma-based electron accelerator and
laser technology.Comment: 5 pages, 3 figure
Sub-eV scalar dark matter through the super-renormalizable Higgs portal
The Higgs portal of the Standard Model provides the opportunity for coupling
to a very light scalar field via the super-renormalizable operator
. This allows for the existence of a very light scalar dark
matter that has coherent interaction with the Standard Model particles and yet
has its mass protected against radiative corrections. We analyze ensuing
constraints from the fifth-force measurements, along with the cosmological
requirements. We find that the detectable level of the fifth-force can be
achieved in models with low inflationary scales, and certain amount of
fine-tuning in the initial deviation of from its minimum.Comment: 6 pages, 3 figures. References added in the revised version
An integrated approach project for the revaluation of a traditional sourdough bread production chain
The influence of organic and conventional farming systems on the performance of a panel of old and modern Italian bread wheat varieties has been evaluated, with the aim to individuate an agronomic protocol suitable for the production of a sourdough bread traditionally prepared in a hill zone of Emilia-Romagna. The agronomic and technological characterisation of the wheat samples obtained in organic and conventional farming conditions has been done and the sensorial qualities of the sourdough bread obtained have been evaluated
Electronic implementations of Interaction-Free Measurements
Three different implementations of interaction-free measurements (IFMs) in
solid-state nanodevices are discussed. The first one is based on a series of
concatenated Mach-Zehnder interferometers, in analogy to optical-IFM setups.
The second one consists of a single interferometer and concatenation is
achieved in the time domain making use of a quantized electron emitter. The
third implementation consists of an asymmetric Aharonov-Bohm ring. For all
three cases we show that the presence of a dephasing source acting on one arm
of the interferometer can be detected without degrading the coherence of the
measured current. Electronic implementations of IFMs in nanoelectronics may
play a fundamental role as very accurate and noninvasive measuring schemes for
quantum devices.Comment: 12 pages, 10 figure
Le retoriche della concordia
L'uso dell'espressione “Les rhétoriques de la concorde”, è la
conseguenza di una scelta ben precisa: attribuire una funzione politica al genere
epidittico. A questa scelta si possono opporre delle critiche legittime, tenuto conto
che le fonti antiche presentano i discorsi epidittici come discorsi di circostanza che
ruotano attorno alle nozioni di elogio e di biasimo. L’idea di una funzione politica
del genere epidittico si fonda su un’interpretazione inizialmente proposta da
Perelman e Olbrechts-Tyteca. A partire da questo - e alla luce dei contributi che la curatela raccoglie - gli autori ragionano sul nesso inscindibile epidittico/politica.The expression "Les rhétoriques de la concorde", is the
consequence of a precise choice: assigning a political function to the
epideictic genre. This choice can be opposed to legitimate criticism, given
that the ancient sources present the epidemic discourses as discourses on circumstance that
revolve around the praise and the blame. The idea of a political function
of the epidemic type is based on an interpretation initially proposed by
Perelman and Olbrechts-Tyteca. Starting from this - and in the light of the contributions that the editors collect - the authors reason about the inseparable epidictic/political link
Coulomb-Blockade directional coupler
A tunable directional coupler based on Coulomb Blockade effect is presented.
Two electron waveguides are coupled by a quantum dot to an injector waveguide.
Electron confinement is obtained by surface Schottky gates on single
GaAs/AlGaAs heterojunction. Magneto-electrical measurements down to 350 mK are
presented and large transconductance oscillations are reported on both outputs
up to 4.2 K. Experimental results are interpreted in terms of Coulomb Blockade
effect and the relevance of the present design strategy for the implementation
of an electronic multiplexer is underlined.Comment: 4 pages, 4 figures, to be published in Applied Physics Letter
Apparatus for time‐resolved measurements of acoustic birefringence in particle dispersions
An apparatus for time‐resolved measurements of the birefringence induced in a particle suspension by an acoustic wave pulse is described. Efficient acoustic coupling is obtained by operating near the transducer resonant frequency and by matching the acoustic impedances of the cell constituents. An almost‐overdamped acoustic configuration can alternatively be employed whenever a faster response is needed. Careful design of the optical setup and of the detection unit minimize diffraction and stress‐birefringence parasitic effects and yields a good responsivity at fairly low acoustic intensities. A test of the apparatus on a colloidal suspension of PTFE rodlike particles is presented and discussed
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