742 research outputs found

    Reply to a Commentary "Asking photons where they have been without telling them what to say"

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    Interesting objections to conclusions of our experiment with nested interferometers raised by Salih in a recent Commentary are analysed and refuted.Comment: Published version (Frontiers in Physics) to revised version of the Commentar

    Interaction-induced localization of anomalously-diffracting nonlinear waves

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    We study experimentally the interactions between normal solitons and tilted beams in glass waveguide arrays. We find that as a tilted beam, traversing away from a normally propagating soliton, coincides with the self-defocusing regime of the array, it can be refocused and routed back into any of the intermediate sites due to the interaction, as a function of the initial phase difference. Numerically, distinct parameter regimes exhibiting this behavior of the interaction are identified.Comment: Physical Review Letters, in pres

    An all-optical event horizon in an optical analogue of a Laval nozzle

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    Exploiting the fact that light propagation in defocusing nonlinear media can mimic the transonic flow of an equivalent fluid, we demonstrate experimentally the formation of an all-optical event horizon in a waveguide structure akin to a hydrodynamic Laval nozzle. The analogue event horizon, which forms at the nozzle throat is suggested as a novel platform for analogous gravity experiments

    Power dependent switching of nonlinear trapping by local photonic potentials

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    We study experimentally and numerically the nonlinear scattering of wave packets by local multi-site guiding centers embedded in a continuous dielectric medium, as a function of the input power and angle of incidence. The extent of trapping into the linear modes of different sites is manipulated as a function of both the input power and incidence angle, demonstrating power-controlled switching of nonlinear trapping by local photonic potentials.Comment: Submitted to Optics Letter

    Dynamics of fluctuations in an optical analog of the Laval nozzle

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    Using the analogy between the description of coherent light propagation in a medium with Kerr nonlinearity by means of nonlinear Schr\"odinger equation and that of a dissipationless liquid we propose an optical analogue of the Laval nozzle. The optical Laval nozzle will allow one to form a transonic flow in which one can observe and study a very unusual dynamics of classical and quantum fluctuations including analogue of the Hawking radiation of real black holes. Theoretical analysis of this dynamics is supported by numerical calculations and estimates for a possible experimental setup are presented.Comment: 7 pages, 4 figure

    Racial Disparities in Head and Neck Cancers in an Urban Hospital

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    Introduction: Head and neck cancer incidence rates are higher for white residents in Philadelphia, while related mortality rates are highest for black residents. It is unclear how risk factors like HPV and smoking contribute to these disparities. The goal of this study is to determine which factors are associated with head and neck cancers in a diverse patient population from a Philadelphia hospital. Methods: Cancer registry data from Thomas Jefferson University was used to obtain records from 922 head and neck cancer patients. One patient of other race was excluded. Twenty in-situ cancer cases were excluded. Chi-square tests were used to examine categorical variables. Logistic and Cox regression models were designed to examine associations with advanced disease and time to mortality. Results: Our sample included 901 patients (769 white, 96 black, 36 Asian). Positive HPV status was most prevalent for white patients (p\u3c 0.0001). Oral cancers were most common among Asians (p\u3c.0001). In univariate analysis, black patients were most likely to die from their cancer. In multivariate analysis, time to death was shorter for current smokers (HR=1.95, CI=1.311-2.901) and former smokers (HR=2.94, CI=1.949-4.387). Positive HPV status was protective (HR=0.34, CI=.244-.481). No significant race effects were observed in multivariate analysis. Conclusions: Results suggest that race is not independently associated with head and neck cancer associated mortality. These results also suggest that some risk factors for head and neck cancer and outcomes may be modified by educational and behavioral interventions

    Salvage Fractionated Stereotactic Re-irradiation (FSRT) for Patients with Recurrent High Grade Gliomas Progressed after Bevacizumab Treatment

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    Purpose/Objectives: Bevacizumab failure is a major clinical problem in the manage- ment of high grade gliomas (HGG), with a median overall survival of less than 4 months (m). This study evaluated the efficacy of fractionated stereotactic re-irradiation (FSRT) for patients with HGG after progression on Bevacizumab. Materials/Methods: Retrospective review was conducted of patients treated with FSRT after progression on bevacizumab. A total of 36 patients were identified. FSRT was most commonly delivered in 3.5 Gy fractions to a total dose of 35 Gy. Survival from initial diagnosis, as well as from recurrence and re-irradiation, were utilized as study endpoints. Univariate and multivariate analysis was performed. Results: Among the 36 patients, 31 patients had recurrent glioblastoma, and 5 patients had recurrent anaplastic astrocytoma. The median time from initial bevacizumab treatment to FSRT was 8.5 m (range 2.3 – 32.0 m). The median plan target volume for FSRT was 27.5 cc (range 1.95 – 165 cc). With a median follow up of 20.4 m, the overall survival of the patients since initial diagnosis was also 24.9 m. The median overall survival after initiation of bevacizumab was 13.4 months. The median overall survival from FSRT was 4.8 m. FSRT treatment was well tolerated with no Grade \u3e3 toxicity. Conclusions: Favorable outcomes were observed in patients with recurrent HGG who received salvage FSRT after bevacizumab failure. The treatment was well tolerated. Prospective study is warranted to further evaluate the efficacy of salvage FSRT for selected patients with recurrent HGG amenable to FSRT, who had failed bevacizumab treatment

    Universality of local weak interactions and its application for interferometric alignment

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    The modification of the effect of interactions of a particle as a function of its pre- and postselected states is analyzed theoretically and experimentally. The universality property of this modification in the case of local interactions of a spatially pre- and postselected particle has been found. It allowed to define an operational approach for characterization of the presence of a quantum particle in a particular place: the way it modifies the effect of local interactions. The experiment demonstrating this universality property provides an efficient interferometric alignment method, in which the beam on a single detector throughout one phase scan yields all misalignment parameters.Comment: 12 pages, 7 figure
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