Quantum Phase Transition in Coupled Spin Ladders

The ground state of an array of coupled, spin-half, antiferromagnetic ladders is studied using spin-wave theory, exact diagonalization (up to 36 sites) and quantum Monte Carlo techniques (up to 256 sites). Our results clearly indicate the occurrence of a zero-temperature phase transition between a N\'eel ordered and a non-magnetic phase at a finite value of the inter-ladder coupling ($\alpha_c\simeq0.3$). This transition is marked by remarkable changes in the structure of the excitation spectrum.Comment: 4 pages, 6 postscript figures, to appear in Physical Review

Dispersive estimates for the Dirac equation in an Aharonov-Bohm field

We prove local smoothing and weighted Strichartz estimates for the Dirac equation with a Aharonov-Bohm potential. The proof relies on an explicit representation of the solution built in terms of spectral projections.Comment: 18 page

On the QCD Evolution of Transverse Momentum Dependent Distributions

We reconsider the evolution equations for transverse momentum dependent distributions recently proposed by us and recast them in a form which allows the comparison with results recently appeared in the literature. We show under which conditions the obtained results might be consistent with each other.Comment: 13 pages, no figures, minor changes to text, one reference adde

ECLAS CONFERENCE GHENT 2018 Landscapes of Conflict

Producción CientíficaThroughout the twentieth century, Friuli Venezia Giulia, the north-eastern region of Italy that borders Austria and Slovenia, played a strategic wartime role. From the Great War to the Cold War, the installation of defensive works including barracks, fortifications and infrastructure distinguished the territory. A significant rationalization in the territory and modification in the organizational structure of the Armed Forces took place from the end of the Cold War, through the EU expansion to the countries located on the north-eastern border of Italy, and up to the Army’s transformation from conscription to voluntary service. The town of Casarsa della Delizia represents a case of important significance due to the presence of the “Trieste” barracks, a settlement of extensive and significant environmental impact, a part of which has not been used for years, becoming over time a landscape-abandonment issue, on which action is needed. The paper focuses on the proposals to recover this former military area as a new integrated part of the city, merging the necessity of saving the past heritage and developing a new landscape vision, bringing together the historical and contemporary ways of living and promoting urban regeneration complex operations.European Joint Doctorate “urbanHIST”. European Union. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 721933

Intermittency in Turbulence: Multiplicative random process in space and time

We present a simple stochastic algorithm for generating multiplicative processes with multiscaling both in space and in time. With this algorithm we are able to reproduce a synthetic signal with the same space and time correlation as the one coming from shell models for turbulence and the one coming from a turbulent velocity field in a quasi-Lagrangian reference frame.Comment: 23 pages, 12 figure

The statistical properties of turbulence in the presence of a smart small-scale control

By means of high-resolution numerical simulations, we compare the statistical properties of homogeneous and isotropic turbulence to those of the Navier-Stokes equation where small-scale vortex filaments are strongly depleted, thanks to a non-linear extra viscosity acting preferentially on high vorticity regions. We show that the presence of such smart small-scale drag can strongly reduce intermittency and non-Gaussian fluctuations. Our results pave the way towards a deeper understanding on the fundamental role of degrees of freedom in turbulence as well as on the impact of (pseudo)coherent structures on the statistical small-scale properties. Our work can be seen as a first attempt to develop smart-Lagrangian forcing/drag mechanisms to control turbulence.Comment: 5 pages, 5 figure

Statistics of small scale vortex filaments in turbulence

We study the statistical properties of coherent, small-scales, filamentary-like structures in Turbulence. In order to follow in time such complex spatial structures, we integrate Lagrangian and Eulerian measurements by seeding the flow with light particles. We show that light particles preferentially concentrate in small filamentary regions of high persistent vorticity (vortex filaments). We measure the fractal dimension of the attracting set and the probability that two particles do not separate for long time lapses. We fortify the signal-to-noise ratio by exploiting multi-particles correlations on the dynamics of bunches of particles. In doing that, we are able to give a first quantitative estimation of the vortex-filaments life-times, showing the presence of events as long as the integral correlation time. The same technique introduced here could be used in experiments as long as one is capable to track clouds of bubbles in turbulence for a relatively long period of time, at high Reynolds numbers; shading light on the dynamics of small-scale vorticity in realistic turbulent flows.Comment: 5 pages, 5 figure

Productivity, networks, and export performance: evidence from a cross-country fi rm dataset

This paper uses a newly assembled multi-country multi-industry fi…rm-level dataset to test the effect of productivity and networking on the export probability of …firms. Results are in line with the new-new trade theory and with the literature on the information value of networks. Firms are more likely to export if they are more productive, larger, and if they bene…fit from foreign networks (ownership and …financial linkages), domestic networks (chamber of commerce, links to regulation), and communication networks (E-mail, internet). Firms bear a lower probability of exporting if they have state or labor networks. Overall, …firms with better network connections by one standard deviation enjoy a 15% higher probability of exporting.new-new trade theory; export probability