Effects of interaction on the diffusion of atomic matter waves in one-dimensional quasi-periodic potentials

We study the behaviour of an ultracold atomic gas of bosons in a bichromatic lattice, where the weaker lattice is used as a source of disorder. We numerically solve a discretized mean-field equation, which generalizes the one-dimensional Aubry-Andr\`e model for particles in a quasi-periodic potential by including the interaction between atoms. We compare the results for commensurate and incommensurate lattices. We investigate the role of the initial shape of the wavepacket as well as the interplay between two competing effects of the interaction, namely self-trapping and delocalization. Our calculations show that, if the condensate initially occupies a single lattice site, the dynamics of the interacting gas is dominated by self-trapping in a wide range of parameters, even for weak interaction. Conversely, if the diffusion starts from a Gaussian wavepacket, self-trapping is significantly suppressed and the destruction of localization by interaction is more easily observable

Localization in momentum space of ultracold atoms in incommensurate lattices

We characterize the disorder induced localization in momentum space for ultracold atoms in one-dimensional incommensurate lattices, according to the dual Aubry-Andr\'e model. For low disorder the system is localized in momentum space, and the momentum distribution exhibits time-periodic oscillations of the relative intensity of its components. The behavior of these oscillations is explained by means of a simple three-mode approximation. We predict their frequency and visibility by using typical parameters of feasible experiments. Above the transition the system diffuses in momentum space, and the oscillations vanish when averaged over different realizations, offering a clear signature of the transition

Coevolution between Terraced Landscapes and Rural Communities: An Integrated Approach Using Expert-Based Assessment and Evaluation of Winegrowers' Perceptions (Northwest Piedmont, Italy)

Terraced landscapes are characterized by many features but are also threatened by abandonment, with the loss of the historical landscape and increased hydrogeological risk. In this research, we developed an innovative integrated approach using expert-based assessment and evaluation of winegrowers’ perceptions to investigate the coevolution between terraced landscapes and rural communities. The aims were as follows: (i) to identify the historical landscape elements, (ii) to identify the landscape dynamics, and (iii) to analyze winegrowers’ perceptions about the historical landscape elements and future development prospects. The methodology was applied to a terraced vineyard landscape (545 ha) located in Piedmont (Italy). The expert-based assessment included historical analyses and field surveys. To evaluate winegrowers’ perceptions, an online questionnaire was used to understand their perceptions about the landscape’s historical elements and dynamics. The results suggest that unique historical landscape elements and traditional practices (vine pergolas supported by stone columns) are conserved in the area, but also highlight some dynamics, including new vine-breeding techniques (espaliers) and new land uses (olive groves, meadows, and woodland). Winegrowers (n = 49) recognized as identity elements the same identified as historical by experts. Regarding future prospects, almost all winegrowers preferred the conservation of vineyards and pergolas. The research methodology was able to show the mutual link between terraced landscapes and rural communities in coevolutionary terms and could be replicated in similar contexts. According to the winegrowers’ awareness, future planning strategies will have to support dynamic conservation of the landscape

The Enzymatic Activity and Molecular Characterization of a Secreted Subtilisin-Like Protease in Microsporum gypseum and Trichophyton vanbreuseghemii

Background: Subtilisin -like proteases are the group of proteases including keratinases found in dermatophytes which de­graded keratin. Determination of the proteases activity of Trichophyton vanbreuseghemii isolates which were obtained from soil and clinical and soil isolates of Microsporum gypseum in Iran and characterization of their genome were aim of present study.Methods: Ezymatic activity was determined by use of chromogenic substrates. The genes, which coded subtilisin-like pro­teases in above-mentioned dermatophytes, was identified and amplified by using specific primers in PCR. Results: The highest yield of enzyme production was observed in only one isolate of T. vanbreuseghemii Ir-84 whereas low enzyme activity was observed in M. gypseum isolates. Homology study of obtained nucleotide as well as amino acid sequences indicated different rates of homology with other subtilisin-like proteases genes in other pathogenic dermato­phytes. Conclusion: Intra-strain differences were observed in production of serine proteinases and molecular characterization of genes encoding such enzymes could be of great interest for studies on pathogenicity and other purposes

I Quaderni di Careggi- Fifth issue- Landscape Observatories

Having regard to Recommendation CM/Rec (2008)3 on the Guidelines for the implementation of the European Landscape Convention, “landscape observatories, centers and institutes” are one of the main instruments for the implementation of landscape policies (II.3.3). They facilitate the collection and exchange of information and study protocols between states and local communities. This issue of the Quaderni di Careggi presents an international overview of the activities of landscape observatories, a reflection on their mission and effectiveness with regard to the ELC objectives, and a reflection on the relationships between the different subjects, thanks to the participation of institutional bodies, public officials as well as researchers and representatives of civil society. It reflects part of the scientific contributions which will be presented during the V Careggi Seminar (Florence, 27-28th June 2013)

Observation of subdiffusion of a disordered interacting system

We study the transport dynamics of matter-waves in the presence of disorder and nonlinearity. An atomic Bose-Einstein condensate that is localized in a quasiperiodic lattice in the absence of atom-atom interaction shows instead a slow expansion with a subdiffusive behavior when a controlled repulsive interaction is added. The measured features of the subdiffusion are compared to numerical simulations and a heuristic model. The observations confirm the nature of subdiffusion as interaction-assisted hopping between localized states and highlight a role of the spatial correlation of the disorder.Comment: 8 pages, to be published on Physical Review Letter