1,606 research outputs found

    Continuous atom laser with Bose-Einstein condensates involving three-body interactions

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    We demonstrate, through numerical simulations, the emission of a coherent continuous matter wave of constant amplitude from a Bose-Einstein Condensate in a shallow optical dipole trap. The process is achieved by spatial control of the variations of the scattering length along the trapping axis, including elastic three body interactions due to dipole interactions. In our approach, the outcoupling mechanism are atomic interactions and thus, the trap remains unaltered. We calculate analytically the parameters for the experimental implementation of this CW atom laser.Comment: 11 pages, 4 figure

    Perturbative analysis of disordered Ising models close to criticality

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    We consider a two-dimensional Ising model with random i.i.d. nearest-neighbor ferromagnetic couplings and no external magnetic field. We show that, if the probability of supercritical couplings is small enough, the system admits a convergent cluster expansion with probability one. The associated polymers are defined on a sequence of increasing scales; in particular the convergence of the above expansion implies the infinite differentiability of the free energy but not its analyticity. The basic tools in the proof are a general theory of graded cluster expansions and a stochastic domination of the disorder

    Step-down from high dose fixed combination therapy in asthma patients: a randomized controlled trial.

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    Asthma guidelines suggest that therapy can be reduced once asthma is controlled. Despite these recommendations, asthmatic patients are seldom stepped down in clinical practice, and questions remain about when and how to reduce asthma therapy. The purpose of the present study was to evaluate lung function and asthma control in patients who were stepped down from the highest recommended dose of inhaled corticosteroid/long acting \u3b22 agonist combination therapy. METHODS: This was a prospective, randomised, controlled, two-arm parallel group study. Asthmatic patients who were fully controlled with a high daily dose (1000/100\u2009\u3bcg) of fluticasone/salmeterol were randomly assigned to 6\u2009months of open-label treatment with either 500/100\u2009\u3bcg fluticasone/salmeterol Diskus daily or 400/24\u2009\u3bcg extrafine beclomethasone/formoterol pMDI daily. The primary outcome was the change in morning peak expiratory flow (PEF) values between baseline and the end of treatment. The secondary outcomes included asthma control and exacerbation frequency. RESULTS: Four hundred twenty-two patients were included in the analysis. The PEF values remained above 95% of the predicted values throughout the study. The end-study morning PEF rates showed equivalence between the groups (difference between means, 2.49\u2009L/min; 95% CI, -13.43 to 18.42). No changes from baseline were detected in PEF and forced expiratory volume in 1 second measured at the clinics, in the symptom scores or in the use of rescue medication. Asthma control was maintained in 95.2% of the patients at 6\u2009months. No significant differences between the groups were detected in any other parameter, including exacerbation frequency and adverse events. CONCLUSIONS: Stepping down patients whose asthma is controlled with the highest recommended dose of fluticasone/salmeterol to either 500/100\u2009\u3bcg fluticasone/salmeterol daily or 400/24\u2009\u3bcg extra-fine beclomethasone/formoterol daily provides comparable maintenance of lung function and asthma control. TRIAL REGISTRATION: clinicaltrials.gov NCT00497237

    Background suppression in massive TeO2_2 bolometers with Neganov-Luke amplified light detectors

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    Bolometric detectors are excellent devices for the investigation of neutrinoless double-beta decay (0νββ\nu\beta\beta). The observation of such decay would demonstrate the violation of lepton number, and at the same time it would necessarily imply that neutrinos have a Majorana character. The sensitivity of cryogenic detectors based on TeO2_2 is strongly limited by the alpha background in the region of interest for the 0νββ\nu\beta\beta of 130^{130}Te. It has been demonstrated that particle discrimination in TeO2_2 bolometers is possible measuring the Cherenkov light produced by particle interactions. However an event-by-event discrimination with NTD-based light detectors has to be demonstrated. We will discuss the performance of a highly-sensitive light detector exploiting the Neganov-Luke effect for signal amplification. The detector, being operated with NTD-thermistor and coupled to a 750 g TeO2_2 crystal, shows the ability for an event-by-event identification of electron/gamma and alpha particles. The extremely low detector baseline noise, RMS 19 eV, demonstrates the possibility to enhance the sensitivity of TeO2_2-based 0νββ\nu\beta\beta experiment to an unprecedented level

    Relaxation Height in Energy Landscapes: an Application to Multiple Metastable States

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    The study of systems with multiple (not necessarily degenerate) metastable states presents subtle difficulties from the mathematical point of view related to the variational problem that has to be solved in these cases. We introduce the notion of relaxation height in a general energy landscape and we prove sufficient conditions which are valid even in presence of multiple metastable states. We show how these results can be used to approach the problem of multiple metastable states via the use of the modern theories of metastability. We finally apply these general results to the Blume--Capel model for a particular choice of the parameters ensuring the existence of two multiple, and not degenerate in energy, metastable states

    A Journey to the West: The Ancient Dispersal of Rice Out of East Asia

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    Rice is one of the most culturally valued and widely grown crops in the world today, and extensive research over the past decade has clarified much of the narrative of its domestication and early spread across East and South Asia. However, the timing and routes of its dispersal into West Asia and Europe, through which rice eventually became an important ingredient in global cuisines, has remained less clear. In this article, we discuss the piecemeal, but growing, archaeobotanical data for rice in West Asia. We also integrate written sources, linguistic data, and ethnohistoric analogies, in order to better understand the adoption of rice outside its regions of origin. The human-mediated westward spread of rice proceeded gradually, while its social standing and culinary uses repeatedly changing over time and place. Rice was present in West Asia and Europe by the tail end of the first millennium BC, but did not become a significant crop in West Asia until the past few centuries. Complementary historical, linguistic, and archaeobotanical data illustrate two separate and roughly contemporaneous routes of westward dispersal, one along the South Asian coast and the other through Silk Road trade. By better understanding the adoption of this water-demanding crop in the arid regions of West Asia, we explore an important chapter in human adaptation and agricultural decision making

    CC chemokine receptor 5 polymorphism in Italian patients with Behcet's disease.

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    Objective. To evaluate the potential role of CC chemokine receptor 5 (CCR5)Δ32 polymorphism in the susceptibility to and clinical expression of Behçet's disease (BD) in a cohort of Italian patients.Methods. One hundred and ninety-six consecutive Italian patients satisfying the ISG criteria for BD were followed up for 8 years, and 180 healthy age- and sex-matched blood donors were molecularly genotyped for the CCR5Δ32 polymorphism. A standard microlymphocytotoxicity technique was used to serotype HLA-B51. The patients were subgrouped on the basis of the presence or absence of clinical manifestations.Results. The distribution of the CCR5Δ32 genotype differed between BD patients and controls (P = 0.02). The CCR5Δ32 allele was more common in BD patients than in controls [P = 0.02, odds ratio (OR) 2.28 (95% CI 1.1, 4.8)]. Carriers of the CCR5Δ32 allele (Δ32/Δ32 + CCR5/Δ32) were significantly more common in BD patients than in controls [P = 0.02, OR 2.37 (95% CI 1.1, 5.1)]. Population-attributable risk was 7.1%. In categorizing patients according to gender, the association between CCR5Δ32 polymorphism and BD was similar in females and males (ORs 2.76 and 2.0, respectively). No significant differences were found when the frequencies of clinical manifestations were compared between CC5RΔ32 allele carriers and non-carriers.Conclusion. CCR5Δ32 polymorphism is associated with an increased susceptibility to develop BD. Chemokines may have a role in the pathophysiology of BD

    Large Deviations Analysis for Distributed Algorithms in an Ergodic Markovian Environment

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    We provide a large deviations analysis of deadlock phenomena occurring in distributed systems sharing common resources. In our model transition probabilities of resource allocation and deallocation are time and space dependent. The process is driven by an ergodic Markov chain and is reflected on the boundary of the d-dimensional cube. In the large resource limit, we prove Freidlin-Wentzell estimates, we study the asymptotic of the deadlock time and we show that the quasi-potential is a viscosity solution of a Hamilton-Jacobi equation with a Neumann boundary condition. We give a complete analysis of the colliding 2-stacks problem and show an example where the system has a stable attractor which is a limit cycle
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