749 research outputs found

    Nonlinear Polariton Fluids in a Flatband Reveal Discrete Gap Solitons

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    Phase frustration in periodic lattices is responsible for the formation of dispersionless flat bands. The absence of any kinetic energy scale makes flat band physics critically sensitive to perturbations and interactions. We report here on the experimental investigation of the nonlinear dynamics of cavity polaritons in the gapped flat band of a one-dimensional Lieb lattice. We observe the formation of gap solitons with quantized size and very abrupt edges, signature of the frozen propagation of switching fronts. This type of gap solitons belongs to the class of truncated Bloch waves, and had only been observed in closed systems up to now. Here the driven-dissipative character of the system gives rise to a complex multistability of the nonlinear domains generated in the flat band. These results open up interesting perspective regarding more complex 2D lattices and the generation of correlated photon phases.Comment: 6 pages, 4 figures + supplemental material (6 pages, 6 figures

    High-resolution mid-infrared spectroscopy based on ultrafast Cr:ZnSe laser

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    High-resolution broadband direct frequency comb spectroscopy in the mid-infrared spectral region is an extremely powerful and versatile experimental technique that allows study of the molecular structure of gaseous compounds with multiple applicative and scientific implications. Here we present the first implementation of an ultrafast Cr:ZnSe mode-locked laser covering more than 7 THz at around the emission wavelength of 2.4 um, for direct frequency comb molecular spectroscopy with a frequency sampling of 220 MHz and a frequency resolution of 100 kHz. This technique is based on a scanning micro-cavity resonator with a Finesse of 12,000 and a diffraction reflecting grating. We demonstrate its application in high-precision spectroscopy of the acetylene molecule by retrieving line center frequencies of more than 68 roto-vibrational lines. Our technique paves the way for real time spectroscopic studies as well as for hyperspectral imaging techniques

    Preferência de Bemisia tabaci, biótipo B (Hemiptera: aleyrodidae) a genótipos de soja.

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    O objetivo do trabalho foi avaliar a preferência de B. tabaci a 18 genótipos de soja com chance de escolha, em condições de casa de vegetação. Os genótipos avaliados foram: BRI 04-01668, BRI 04-01685, BRI 04-02770, BRI 04-02855, BRI 04-02935, BRI 04-02983, BRS 7860RR, BRS Barreira, BRS Gisele RR, BRS Juliana, BRS Valiosa RR, BRSGO 7960, BRSGO 8060, CD219, CD 215, Emgopa 302RR, IAC 17 e IAC 19. Os materiais com menores infestações de ovos e ninfas foram: BRI 04-01668, BRI 04-01685, BRI 04-02770 e IAC 17 (padrão de resistência) e os mais infestados foram BRS Juliana RR e Emgopa 302RR Os genótipos BRS 7860RR e BRSGO 8060 apresentaram o mesmo perfil de não preferência que IAC19 (padrão de resistência)

    Asymmetric Fluid Criticality I: Scaling with Pressure Mixing

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    The thermodynamic behavior of a fluid near a vapor-liquid and, hence, asymmetric critical point is discussed within a general ``complete'' scaling theory incorporating pressure mixing in the nonlinear scaling fields as well as corrections to scaling. This theory allows for a Yang-Yang anomaly in which \mu_{\sigma}^{\prime\prime}(T), the second temperature derivative of the chemical potential along the phase boundary, diverges like the specific heat when T\to T_{\scriptsize c}; it also generates a leading singular term, |t|^{2\beta}, in the coexistence curve diameter, where t\equiv (T-T_{\scriptsize c}) /T_{\scriptsize c}. The behavior of various special loci, such as the critical isochore, the critical isotherm, the k-inflection loci, on which \chi^{(k)}\equiv \chi(\rho,T)/\rho^{k} (with \chi = \rho^{2} k_{\scriptsize B}TK_{T}) and C_{V}^{(k)}\equiv C_{V}(\rho,T)/\rho^{k} are maximal at fixed T, is carefully elucidated. These results are useful for analyzing simulations and experiments, since particular, nonuniversal values of k specify loci that approach the critical density most rapidly and reflect the pressure-mixing coefficient. Concrete illustrations are presented for the hard-core square-well fluid and for the restricted primitive model electrolyte. For comparison, a discussion of the classical (or Landau) theory is presented briefly and various interesting loci are determined explicitly and illustrated quantitatively for a van der Waals fluid.Comment: 21 pages in two-column format including 8 figure

    Changes in clinical characteristics and outcomes of patients admitted to inpatient cardiac rehabilitation

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    Aims: Cardiac rehabilitation (CR) have proven to be effective and beneficial in middle-aged and older patients. However, solid data in large cohorts of elderly individuals are yet to be explored. This retrospective study investigated the general characteristics, outcomes, and the level of re-sponse of patients referred to CR over 13 consecutive years. Methods: We reviewed the medical records of patients admitted to Villa Pineta Rehabilitation Hospital for exercise-based CR from 2006 to 2018. Patients’ baseline characteristics and changes following CR in upper limb weight-lifting test (ULW), 30-second sit-to-stand test (30STS), and the 6-minute walking test (6MWT) with associated Borg-related dyspnea (D) and fatigue (F) were collected. We also calculated the number of individuals reaching the minimal clinically relevant change (MCRC) following CR for each outcome. Results: 1551 patients (70.2 ± 9.7 years, 66% men) with complete data set were in-cluded in the analysis. Coronary artery bypass graft and cardiac valve replacement surgery were the most frequent surgical procedures leading to CR referral (41.1% and 35.8%, respectively). The patients’ age (p = 0.03), number of total comorbidities (p < 0.0001), and post-surgical complica-tions (p = 0.02) significantly increased over time. In contrast, the average absolute changes in ULW, 30STS and 6MWT with associated D and F, and the proportion of patients reaching the re-spective MCRC, remained constant over the same period. Conclusion: Patients admitted to exer-cise-based CR were older and had more comorbidities and complications over time. Outcomes, however, were not influenced in terms of absolute change nor clinically meaningful response

    Slow relaxation in weakly open vertex-splitting rational polygons

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    The problem of splitting effects by vertex angles is discussed for nonintegrable rational polygonal billiards. A statistical analysis of the decay dynamics in weakly open polygons is given through the orbit survival probability. Two distinct channels for the late-time relaxation of type 1/t^delta are established. The primary channel, associated with the universal relaxation of ''regular'' orbits, with delta = 1, is common for both the closed and open, chaotic and nonchaotic billiards. The secondary relaxation channel, with delta > 1, is originated from ''irregular'' orbits and is due to the rationality of vertices.Comment: Key words: Dynamics of systems of particles, control of chaos, channels of relaxation. 21 pages, 4 figure
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