2,965 research outputs found
On the Commutative Equivalence of Context-Free Languages
The problem of the commutative equivalence of context-free and regular languages is studied. In particular conditions ensuring that a context-free language of exponential growth is commutatively equivalent with a regular language are investigated
Environment induced incoherent controllability
We prove that the environment induced entanglement between two non
interacting, two-dimensional quantum systems S and P can be used to control the
dynamics of S by means of the initial state of P. Using a simple, exactly
solvable model, we show that both accessibility and controllability of S can be
achieved under suitable conditions on the interaction of S and P with the
environment.Comment: revtex4, 5 page
"Hidden” degassing from streams: estimation of the CO2 release from the thermal springs of Sperchios Basin, Greece
Areas located at plate boundaries are characterized by the presence of seismic, volcanic, and geothermal activity, as well as ore deposition. Such processes are enhanced by the circulation of hydrothermal fluids in the crust transporting volatiles from either the deep crust or the mantle to the surface. Intense geodynamic activity is also taking place in Greece giving rise to: (i) the highest seismicity in Europe, (ii) the presence of an active volcanic arc and numerous areas of anomalously high geothermal gradient, and (iii) a widespread occurrence of thermal springs. Elevated heat flow values are concentrated in Sperchios basin, an area characterised by a system of deeply rooted extensional faults and quaternary volcanic activity. This regime favoured the formation of hydrothermal systems, the surface expression of which are thermal springs with intense bubbling of CO2-rich gases. Flux measurements in the bubbling pools were made with the floating chamber method. The highest bubbling CO2 output is found in Thermopyles and Psoroneria (1 and 2 t/d, respectively). The outgoing channels of these springs have an elevated flow (>250 l/s) of gas-charged water (>15 mmol/l of CO2). Although no bubbling is noticed along the stream, the CO2 content decreases by an order of magnitude after few hundreds of metres, indicating an intense degassing from the water. Taking into account the water flow and the amount of CO2 lost to the atmosphere, the CO2 output of the outgoing channels is quantified in >10 t/d for Thermopyles and 9 t/d for Psoroneria. An estimation is also made at Ypati, Kamena Vourla, Koniavitis and Edipsos, where the mean values reach 1 t/d of CO2 for each spring. The obtained values are always higher respect to the estimated outputs from visible bubbling, suggesting that most of the degassing is “hidden”. Furthermore, the loss of CO2 from the water determines a shift in dissolved carbonate species as demonstrated by the pH increase along the channel that leads eventually to an oversaturation in carbonate minerals and therefore travertine deposition. To sum up, the total CO2 output of the study area is estimated at 30 t/d, with the major contribution deriving from the degassing along the outflow channels of the thermal springs. Such output is comparable to that of the single active volcanic systems along the South Aegean Volcanic Arc (Sousaki, Methana, Milos, Santorini, Kos and Nisyros) and highlights the importance of “hidden” degassing along CO2-oversaturated streams
Information-theory-based solution of the inverse problem in classical statistical mechanics
We present a procedure for the determination of the interaction potential
from the knowledge of the radial pair distribution function. The method,
realized inside an inverse Monte Carlo simulation scheme, is based on the
application of the Maximum Entropy Principle of information theory and the
interaction potential emerges as the asymptotic expression of the transition
probability. Results obtained for high density monoatomic fluids are very
satisfactory and provide an accurate extraction of the potential, despite a
modest computational effort.Comment: 9 pages, 2 figure
Palermo 2010 - Campagna di monitoraggio sismo-acustico sottomarino dell’area epicentrale del terremoto di Palermo del 6 settembre 2002
Search complexity and resource scaling for the quantum optimal control of unitary transformations
The optimal control of unitary transformations is a fundamental problem in
quantum control theory and quantum information processing. The feasibility of
performing such optimizations is determined by the computational and control
resources required, particularly for systems with large Hilbert spaces. Prior
work on unitary transformation control indicates that (i) for controllable
systems, local extrema in the search landscape for optimal control of quantum
gates have null measure, facilitating the convergence of local search
algorithms; but (ii) the required time for convergence to optimal controls can
scale exponentially with Hilbert space dimension. Depending on the control
system Hamiltonian, the landscape structure and scaling may vary. This work
introduces methods for quantifying Hamiltonian-dependent and kinematic effects
on control optimization dynamics in order to classify quantum systems according
to the search effort and control resources required to implement arbitrary
unitary transformations
Quantum measurement of a mesoscopic spin ensemble
We describe a method for precise estimation of the polarization of a
mesoscopic spin ensemble by using its coupling to a single two-level system.
Our approach requires a minimal number of measurements on the two-level system
for a given measurement precision. We consider the application of this method
to the case of nuclear spin ensemble defined by a single electron-charged
quantum dot: we show that decreasing the electron spin dephasing due to nuclei
and increasing the fidelity of nuclear-spin-based quantum memory could be
within the reach of present day experiments.Comment: 8 pages, 2 figures; minor changes, published versio
THE EFFECT OF PRODUCTION SYSTEM INFORMATION ON CONSUMER EXPECTATION AND ACCEPTABILITY OF LECCESE LAMB MEAT
Twenty lamb meat’s habitual consumers (eight females and twelve males, from 25 to 62 yrs of age) took part in a centrallocation test, organised to assess consumers’ expectations generated by information on animal feeding system, lambs fedwith maternal milk from mothers reared on grass (T1) versus lambs fed with maternal milk from mothers reared on stall(T2), and to assess the effect of this knowledge on the hedonic ratings of lamb meat from the Leccese breed. Using anone-point hedonic scale, first blind and then informed scores were collected on two types of Leccese meat. The blind testprovided information which was different from informed test; in fact, T2 meat receiving higher hedonic scores than T1 meat. Onthe contrary, with the label information on animal feeding system, meat from T1 lambs was liked more than meat from T2lambs. The lamb meat’s habitual consumers showed a higher interest in extrinsic quality attributes which referred to the origin orproduction system
Mental, Social and Visual Alienation in D’Alessandro’s Photography
This chapter analyzes the first of several photobooks that illustrated the reform of psychiatric health care in Italy in the 1960s and 1970s: Luciano D’Alessandro’s 1969 Gli esclusi. In 1967, D’Alessandro was invited by the director of the asylum of Nocera Superiore, Sergio Piro, to document through photography the abysmal conditions of the “total institution” that was the pre-reform mental hospital. D’Alessandro first published a small selection of photos, in Popular Photography Italiana (1967), which he then expanded in Gli esclusi. This chapter claims that, in the evolution between the two publications, we can read the complex and multilayered notion of alienation that informed the work of reform, especially that of one of the most famous figures associated with it, Franco Basaglia. By analyzing D’Alessandro’s Gli esclusi through the notion of alienation, this chapter lets what Sekula calls the conditions of “readability” of the photographic message emerge
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