16,870 research outputs found
Discrete-Time Controllability for Feedback Quantum Dynamics
Controllability properties for discrete-time, Markovian quantum dynamics are
investigated. We find that, while in general the controlled system is not
finite-time controllable, feedback control allows for arbitrary asymptotic
state-to-state transitions. Under further assumption on the form of the
measurement, we show that finite-time controllability can be achieved in a time
that scales linearly with the dimension of the system, and we provide an
iterative procedure to design the unitary control actions
Remarks on Neumann boundary problems involving Jacobians
In this short note we explore the validity of Wente-type estimates for
Neumann boundary problems involving Jacobians. We show in particular that such
estimates do not in general hold under the same hypotheses on the data for
Dirichlet boundary problems
Rural landscape valuation in a cross-border region
The rural landscape is one of the most valuable agricultural externalities and it is often affected by modifications in the agricultural production process. Moreover, some rural areas are deteriorating due to the depopulation process while others are being transformed owing to socio-economic pressures. However, should agricultural policies concerning landscape preservation only be considered as cost items or should they be seen as sources of social benefits able to justify economic support? On this basis two surveys were carried out in order to study the economic value of the rural landscape, focusing in particular on viticulture. Both studies covered quality wine-producing areas on the Italian/Slovenian border: The Controlled Denomination of Origin zones of âCollioâ and âColli Orientali del Friuliâ in Italy, and the municipality of Brda in Slovenia. Both surveys assessed the economic value of the rural landscape in order to estimate the social benefit that populations attach to landscape preservation measures. Despite the fact that similar methods were applied, results differed. The peculiar backgrounds affected our results in two ways. Firstly we found that there was a considerable difference in the way Italians and Slovenes valued the rural landscape. While Italians considered the development and extension of vineyards to be very important in counteracting the abandonment of rural areas, Slovenes preferred âtraditionalâ landscapes (orchards, grasslands and vineyards). Secondly, in Slovenia it was difficult to apply the contingent valuation method, which is based on a hypothetical market scenario. More research should be carried out in order to study the methods that best fitthe preferences for rural landscape.rural landscape, contingent valuation method, Collio (Italy), Colli orientali del Friuli (Italy), Brda
Pimsner algebras and circle bundles
We report on the connections between noncommutative principal circle bundles,
Pimsner algebras and strongly graded algebras. We illustrate several results
with the examples of quantum weighted projective and lens spaces and
theta-deformations.Comment: 24 pages. v3: Updated title. No changes in the scientific content and
result
Accurate phase diagram of tetravalent DNA nanostars
We evaluate, by means of molecular dynamics simulations employing a realistic
DNA coarse-grained model, the phase behaviour and the structural and dynamic
properties of tetravalent DNA nanostars, i.e. nanoconstructs completely made of
DNA. We find that, as the system is cooled down, tetramers undergo a
gas--liquid phase separation in a region of concentrations which, if the
difference in salt concentration is taken into account, is comparable with the
recently measured experimental phase diagram [S. Biffi \textit{et al}, Proc.
Natl. Acad. Sci, \textbf{110}, 15633 (2013)]. We also present a mean-field free
energy for modelling the phase diagram based on the bonding contribution,
derived by Wertheim in its studies of associating liquids, combined with mass
action law expressions appropriate for DNA binding and a numerically evaluated
reference free energy. The resulting free energy qualitatively reproduces the
numerical data. Finally, we report information on the nanostar structure, e.g.
geometry and flexibility of the single tetramer and of the collective
behaviour, providing a useful reference for future small angle scattering
experiments, for all investigated temperatures and concentrations.Comment: 10 pages, 11 figure
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