Explicit estimates on the measure of primary KAM tori

From KAM Theory it follows that the measure of phase points which do not lie on Diophantine, Lagrangian, "primary" tori in a nearly--integrable, real--analytic Hamiltonian system is $O(\sqrt{\varepsilon})$, if $\varepsilon$ is the size of the perturbation. In this paper we discuss how the constant in front of $\sqrt{\varepsilon}$ depends on the unperturbed system and in particular on the phase--space domain

The urban strategic planning in the peripherical regions: the case of Catania (Sicily)

More and more regional development appears as an effect of the role that cities are able to carry out in the territory. This implies reconsidering not only resources which are available to a city but, above all, its ability to organize urban activities and functions. If these considerations have already found careful appraisal in the most developed regions, by means of the renewal of instruments for the strategic planning of cities, it seems still insufficient the use of these new planning instruments in the less developed regions, although their primary role in the processes of local development. In Southern Italy, for instance, the proliferation of financial support from various sources (E.U., National Government and Regional ones), which imposes plans at different scales (the interregional one, the among cities one and the among suburbs one), and the emergence of actors and stakeholders, also within the presence of public order problems and infrastructural deficiencies, constitute a network that bridles and conditions the city activities and functions, on one side, but can also be a set of occasions that - if used - can push the city towards development itineraries, on the other side. With our paper we propose to compare some experiences of strategic planning in the Southern Italy and to analyse the case of Catania (a central city in an Objective 1 region, Sicily), putting in evidence how the new Plans give order to the activities and the functions of the city, trying to achieve one balanced and sustainable development, by means of the recovery of urban identity.

A Multiphase First Order Model for Non-Equilibrium Sand Erosion, Transport and Sedimentation

Three phenomena are involved in sand movement: erosion, wind transport, and sedimentation. This paper presents a comprehensive easy-to-use multiphase model that include all three aspects with a particular attention to situations in which erosion due to wind shear and sedimentation due to gravity are not in equilibrium. The interest is related to the fact that these are the situations leading to a change of profile of the sand bed

Dissipative behaviour of reinforced-earth retaining structures under severe ground motion

This paper focuses on the seismic performance of geosynthetic-reinforced retaining walls (GRWs) that several evidences have shown to be generally adequate. This can be attributed to the dissipation of energy produced by the internal plastic mechanisms activated during the seismic shaking, and to an overall ductile behaviour related to the large deformation that can be accommodated by the soil-reinforcement system. Using a number of numerical computations, this work compares the behaviour of three idealized structures that were conceived in order to have a similar seismic resistance, that however is activated through different plastic mechanisms. The analyses include numerical pseudo-static computations, carried out iteratively to failure, and time-domain nonlinear dynamic analyses, in which acceleration time-histories were applied to the bottom boundary of the same numerical models used for the pseudo-static analyses. The results of the dynamic analyses were interpreted in the light of the plastic mechanisms obtained with the pseudo-static procedure, confirming that GRWs develop local plastic mechanisms during strong motion resulting in a significant improvement of their seismic performance

The spin-orbit resonances of the Solar system: A mathematical treatment matching physical data

In the mathematical framework of a restricted, slightly dissipative spin-orbit model, we prove the existence of periodic orbits for astronomical parameter values corresponding to all satellites of the Solar system observed in exact spin-orbit resonance

Traffic Engineering with Segment Routing: SDN-based Architectural Design and Open Source Implementation

Traffic Engineering (TE) in IP carrier networks is one of the functions that can benefit from the Software Defined Networking paradigm. By logically centralizing the control of the network, it is possible to "program" per-flow routing based on TE goals. Traditional per-flow routing requires a direct interaction between the SDN controller and each node that is involved in the traffic paths. Depending on the granularity and on the temporal properties of the flows, this can lead to scalability issues for the amount of routing state that needs to be maintained in core network nodes and for the required configuration traffic. On the other hand, Segment Routing (SR) is an emerging approach to routing that may simplify the route enforcement delegating all the configuration and per-flow state at the border of the network. In this work we propose an architecture that integrates the SDN paradigm with SR-based TE, for which we have provided an open source reference implementation. We have designed and implemented a simple TE/SR heuristic for flow allocation and we show and discuss experimental results.Comment: Extended version of poster paper accepted for EWSDN 2015 (version v4 - December 2015

Dynamical spin properties of confined Fermi and Bose systems in presence of spin-orbit coupling

Due to the recent experimental progress, tunable spin-orbit (SO) interactions represent ideal candidates for the control of polarization and dynamical spin properties in both quantum wells and cold atomic systems. A detailed understanding of spin properties in SO coupled systems is thus a compelling prerequisite for possible novel applications or improvements in the context of spintronics and quantum computers. Here we analyze the case of equal Rashba and Dresselhaus couplings in both homogeneous and laterally confined two-dimensional systems. Starting from the single-particle picture and subsequently introducing two-body interactions we observe that periodic spin fluctuations can be induced and maintained in the system. Through an analytical derivation we show that the two-body interaction does not involve decoherence effects in the bosonic dimer, and, in the repulsive homogeneous Fermi gas it may be even exploited in combination with the SO coupling to induce and tune standing currents. By further studying the effects of a harmonic lateral confinement --a particularly interesting case for Bose condensates-- we evidence the possible appearance of non-trivial {\it spin textures}, whereas the further application of a small Zeeman-type interaction can be exploited to fine-tune the system polarizability.Comment: 13 pages, 3 figure

Regulation, formal and informal enforcement and the development of the household loan market. Lessons from Italy.

Regulation and contract enforcement may be important determinants of the development of the household loan market, as much as they are of the supply of corporate loans on which the literature has focused. This paper draws on the Italian experience to provide evidence that formal and informal institutions and banking regulation are crucial determinants of availability and cost of the household credit. Historically the Italian household credit market has been very small by international standards and its degree of development differs considerably across local markets. It has grown very fast over the last decade. This paper argues that the traditional small size reflects the joint operation of more limited legal and informal enforcement and tight financial regulation. Differences within Italy in the efficiency of the courts, in social trust and in exposure to regulation explain the geographical differences, while massive deregulation of market entry during the 1990s spurred supply and led to fast lending growth. This evidence, together with marked differences in the quality of legal enforcement, endowment of social capital and tightness of financial regulation across countries, implies that the forces found in Italy are likely to be a major explanation for the international differences in the size of the household loan market.consumer loans, financial liberalization, financial contracts enforcement