8,579 research outputs found

    Matter wave quantum dots (anti-dots) in ultracold atomic Bose-Fermi mixtures

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    The properties of ultracold atomic Bose-Fermi mixtures in external potentials are investigated and the existence of gap solitons of Bose-Fermi mixtures in optical lattices demonstrated. Using a self-consistent approach we compute the energy spectrum and show that gap solitons can be viewed as matter wave realizations of quantum dots (anti-dots) with the bosonic density playing the role of trapping (expulsive) potential for the fermions. The fermionic states trapped in the condensate are shown to be at the bottom of the Fermi sea and therefore well protected from thermal decoherence. Energy levels, filling factors and parameters dependence of gap soliton quantum dots are also calculated both numerically and analytically.Comment: Extended version of talk given at the SOLIBEC conference, Almagro, Spain, 8-12 February 2005. To be published on Phys.Rev.

    Hierarchy of boundary driven phase transitions in multi-species particle systems

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    Interacting systems with KK driven particle species on a open chain or chains which are coupled at the ends to boundary reservoirs with fixed particle densities are considered. We classify discontinuous and continuous phase transitions which are driven by adiabatic change of boundary conditions. We build minimal paths along which any given boundary driven phase transition (BDPT) is observed and reveal kinetic mechanisms governing these transitions. Combining minimal paths, we can drive the system from a stationary state with all positive characteristic speeds to a state with all negative characteristic speeds, by means of adiabatic changes of the boundary conditions. We show that along such composite paths one generically encounters ZZ discontinuous and 2(K−Z)2(K-Z) continuous BDPTs with ZZ taking values 0≀Z≀K0\leq Z\leq K depending on the path. As model examples we consider solvable exclusion processes with product measure states and K=1,2,3K=1,2,3 particle species and a non-solvable two-way traffic model. Our findings are confirmed by numerical integration of hydrodynamic limit equations and by Monte Carlo simulations. Results extend straightforwardly to a wide class of driven diffusive systems with several conserved particle species.Comment: 12 pages, 11 figure

    Small-amplitude excitations in a deformable discrete nonlinear Schroedinger equation

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    A detailed analysis of the small-amplitude solutions of a deformed discrete nonlinear Schr\"{o}dinger equation is performed. For generic deformations the system possesses "singular" points which split the infinite chain in a number of independent segments. We show that small-amplitude dark solitons in the vicinity of the singular points are described by the Toda-lattice equation while away from the singular points are described by the Korteweg-de Vries equation. Depending on the value of the deformation parameter and of the background level several kinds of solutions are possible. In particular we delimit the regions in the parameter space in which dark solitons are stable in contrast with regions in which bright pulses on nonzero background are possible. On the boundaries of these regions we find that shock waves and rapidly spreading solutions may exist.Comment: 18 pages (RevTex), 13 figures available upon reques

    Motor skills in children with primary headache: A pilot case-control study

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    Background: Headache is the most common painful manifestation in the developmental age, often accompanied by severe disability such as scholastic absenteeism, low quality of academic performance and compromised emotional functioning. The aim of the study is to evaluate praxic abilities in a population of children without aural migraine. Materials and methods: The test population consists of 10 subjects without migraine without aura (MwA), (8 Males) (mean age 8.40, SD ± 1.17) and 11 healthy children (7 Males) (mean age 8.27; SD ± 1.10; p = 0.800). All subjects underwent evaluation of motor coordination skills through the Battery for Children Movement Assessment (M-ABC). Results: The two groups (10 MwA vs 11 Controls) were similar for age (8.40 ± 1.17 vs 8.27 ± 1.10; p = 0.800), sex (p = 0.730), and BMI (p = 0.204). The migraine subjects show an average worse performance than the Movement ABC; specifically, migraineurs show significantly higher total score values (31.00 ± 23.65 vs 4.72 ± 2.61; p = 0.001), manual dexterity (12.10 ± 11.20 vs 2.04 ± 2.65; p = 0.009) and balance (14.85 ± 10.08 vs. 1.04 ± 1.05; p <0.001). The mean percentile of migraine performance is significantly reduced compared to controls (9.00 ± 3.82 vs 51.00 ± 24.34, p <0.001) (Table 1). Conclusion: Migraine can alter many cognitive and executive functions such as motor skills in developmental age

    Three dimensional imaging of short pulses

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    We exploit a slightly noncollinear second-harmonic cross-correlation scheme to map the 3D space-time intensity distribution of an unknown complex-shaped ultrashort optical pulse. We show the capability of the technique to reconstruct both the amplitude and the phase of the field through the coherence of the nonlinear interaction down to a resolution of 10 Ό\mum in space and 200 fs in time. This implies that the concept of second-harmonic holography can be employed down to the sub-ps time scale, and used to discuss the features of the technique in terms of the reconstructed fields.Comment: 16 pages, 6 figure

    Wannier functions of elliptic one-gap potentials

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    Wannier functions of the one dimensional Schroedinger equation with elliptic one gap potentials are explicitly constructed. Properties of these functions are analytically and numerically investigated. In particular we derive an expression for the amplitude of the Wannier function in the origin, a power series expansion valid in the vicinity of the origin and an asymptotic expansion characterizing the decay of the Wannier function at large distances. Using these results we construct an approximate analytical expression of the Wannier function which is valid in the whole spatial domain and is in good agreement with numerical results.Comment: 24 pages, 5 figure

    Hyaline fibromatosis syndrome (juvenile hyaline fibromatosis): whole-body MR findings in two siblings with different subcutaneous nodules distribution

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    Abstract: Hyaline fibromatosis syndrome (juvenile hyaline fibromatosis) is a rare, progressive, autosomal recessive disorder whose main hallmark is the deposition of amorphous hyaline material in soft tissues, with an evolutionary course and health impairment. It may present involvement of subcutaneous or periskeletal soft tissue, or may develop as a visceral infiltration entity with poor prognosis. Very few radiological data about this inherited condition have been reported, due to the extreme rarity of disease. We herein present a case of two siblings, affected by different severity of the disease, with different clinical features. They were examined by whole-body MR (WBMR) in order to assess different lesions localization, to rule out any visceral involvement and any other associated anomalies and to define patients\ue2\u80\u99 management

    Adiabatic Compression of Soliton Matter Waves

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    The evolution of atomic solitary waves in Bose-Einstein condensate (BEC) under adiabatic changes of the atomic scattering length is investigated. The variations of amplitude, width, and velocity of soliton are found for both spatial and time adiabatic variations. The possibility to use these variations to compress solitons up to very high local matter densities is shown both in absence and in presence of a parabolic confining potential.Comment: to appear in J.Phys.
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