450 research outputs found
Participatory design, beyond the local
This workshop aims at stimulating and opening a debate around the capacity of Participatory Design (PD) and other co-design approaches to deliver outcomes and methodologies that can have an impact and value for reuse well beyond the local context in which they were originally developed. This will be achieved by stimulating the submission of position papers by researchers from the PD community and beyond.These papers will be discussed during the workshop in order to identify challenges, obstacles but also potentials for scaling up PD processes and results from the local to the global.</p
Dynamics of Josephson junctions and single-flux-quantum networks with superconductor-insulator-normal metal junction shunts
Within the framework of the microscopic model of tunneling, we modelled the
behavior of the Josephson junction shunted by the
Superconductor-Insulator-Normal metal (SIN) tunnel junction. We found that the
electromagnetic impedance of the SIN junction yields both the
frequency-dependent damping and dynamic reactance which leads to an increase in
the effective capacitance of the circuit. We calculated the dc I-V curves and
transient characteristics of these circuits and explained their quantitative
differences to the curves obtained within the resistively shunted junction
model. The correct operation of the basic single-flux-quanta circuits with such
SIN-shunted junctions, i.e. the Josephson transmission line and the toggle
flip-flop, have also been modelled.Comment: 8 pages incl. 7 figure
The D^6 R^4 term in type IIB string theory on T^2 and U-duality
We propose a manifestly U-duality invariant modular form for the D^6 R^4
interaction in the effective action of type IIB string theory compactified on
T^2. It receives perturbative contributions upto genus three, as well as
non-perturbative contributions from D-instantons and (p,q) string instantons
wrapping T^2. Our construction is based on constraints coming from string
perturbation theory, U-duality, the decompactification limit to ten dimensions,
and the equality of the perturbative part of the amplitude in type IIA and type
IIB string theories. Using duality, parts of the perturbative amplitude are
also shown to match exactly the results obtained from eleven dimensional
supergravity compactified on T^3 at one loop. We also obtain parts of the genus
one and genus k amplitudes for the D^{2k} R^4 interaction for arbitrary k > 3.
We enhance a part of this amplitude to a U-duality invariant modular form.Comment: 42 pages, LaTe
Ground states for a class of deterministic spin models with glassy behaviour
We consider the deterministic model with glassy behaviour, recently
introduced by Marinari, Parisi and Ritort, with \ha\ , where is the discrete sine Fourier transform. The
ground state found by these authors for odd and prime is shown to
become asymptotically dege\-ne\-ra\-te when is a product of odd primes,
and to disappear for even. This last result is based on the explicit
construction of a set of eigenvectors for , obtained through its formal
identity with the imaginary part of the propagator of the quantized unit
symplectic matrix over the -torus.Comment: 15 pages, plain LaTe
Deterministic spin models with a glassy phase transition
We consider the infinite-range deterministic spin models with Hamiltonian
, where is the quantization of a
chaotic map of the torus. The mean field (TAP) equations are derived by summing
the high temperature expansion. They predict a glassy phase transition at the
critical temperature .Comment: 8 pages, no figures, RevTex forma
Holographic Pomeron and the Schwinger Mechanism
We revisit the problem of dipole-dipole scattering via exchanges of soft
Pomerons in the context of holographic QCD. We show that a single closed string
exchange contribution to the eikonalized dipole-dipole scattering amplitude
yields a Regge behavior of the elastic amplitude; the corresponding slope and
intercept are different from previous results obtained by a variational
analysis of semi-classical surfaces. We provide a physical interpretation of
the semi-classical worldsheets driving the Regge behavior for (-t)>0 in terms
of worldsheet instantons. The latter describe the Schwinger mechanism for
string pair creation by an electric field, where the longitudinal electric
field E_L=\sigma_T tanh(\chi/2) at the origin of this non-perturbative
mechanism is induced by the relative rapidity {\chi} of the scattering dipoles.
Our analysis naturally explains the diffusion in the impact parameter space
encoded in the Pomeron exchange; in our picture, it is due to the Unruh
temperature of accelerated strings under the electric field. We also argue for
the existence of a "micro-fireball" in the middle of the transverse space due
to the soft Pomeron exchange, which may be at the origin of the thermal
character of multiparticle production in ep/pp collisions. After summing over
uncorrelated multi-Pomeron exchanges, we find that the total dipole-dipole
cross section obeys the Froissart unitarity bound.Comment: 17 pages, 4 figures, version 2: minor typos corrected, references
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Non-exponential relaxation for anomalous diffusion
We study the relaxation process in normal and anomalous diffusion regimes for
systems described by a generalized Langevin equation (GLE). We demonstrate the
existence of a very general correlation function which describes the relaxation
phenomena. Such function is even; therefore, it cannot be an exponential or a
stretched exponential. However, for a proper choice of the parameters, those
functions can be reproduced within certain intervals with good precision. We
also show the passage from the non-Markovian to the Markovian behaviour in the
normal diffusion regime. For times longer than the relaxation time, the
correlation function for anomalous diffusion becomes a power law for broad-band
noise.Comment: 6 pages, 2 figure
Propagation of charged particle waves in a uniform magnetic field
This paper considers the probability density and current distributions
generated by a point-like, isotropic source of monoenergetic charges embedded
into a uniform magnetic field environment. Electron sources of this kind have
been realized in recent photodetachment microscopy experiments. Unlike the
total photocurrent cross section, which is largely understood, the spatial
profiles of charge and current emitted by the source display an unexpected
hierarchy of complex patterns, even though the distributions, apart from
scaling, depend only on a single physical parameter. We examine the electron
dynamics both by solving the quantum problem, i. e., finding the energy Green
function, and from a semiclassical perspective based on the simple cyclotron
orbits followed by the electron. Simulations suggest that the semiclassical
method, which involves here interference between an infinite set of paths,
faithfully reproduces the features observed in the quantum solution, even in
extreme circumstances, and lends itself to an interpretation of some (though
not all) of the rich structure exhibited in this simple problem.Comment: 39 pages, 16 figure
RESEARCHES REGARDING THE OBTAINING OF JUICE FROM SUGAR SORGHUM STALK
Sugar sorghum is a technical plant with high energy value due to the high productivity obtained per hectare. By pressing of sugar sorghum strains it can be obtained a juice that can be further used in various forms: alcohol, ethanol, etc
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