364 research outputs found

    Influence of a classical homogeneous gravitational field on dissipative dynamics of the Jaynes-Cummings model with phase damping

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    In this paper, we study the dissipative dynamics of the Jaynes-Cummings model with phase damping in the presence of a classical homogeneous gravitational field. The model consists of a moving two-level atom simultaneously exposed to the gravitational field and a single-mode traveling radiation field in the presence of the phase damping. We present a quantum treatment of the internal and external dynamics of the atom based on an alternative su(2) dynamical algebraic structure. By making use of the super-operator technique, we obtain the solution of the master equation for the density operator of the quantum system, under the Markovian approximation. Assuming that initially the radiation field is prepared in a Glauber coherent state and the two-level atom is in the excited state, we investigate the influence of gravity on the temporal evolution of collapses and revivals of the atomic population inversion, atomic dipole squeezing, atomic momentum diffusion, photon counting statistics and quadrature squeezing of the radiation field in the presence of phase damping.Comment: 25 pages, 15 figure

    A breakthrough dynamic-osmotic membrane bioreactor/nanofiltration hybrid system for real municipal wastewater treatment and reuse.

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    This study designed a Dynamic-Osmotic membrane bioreactor/nanofiltration (OsMBR/NF) system for municipal wastewater treatment and reuse. Results indicated that a continuously rotating FO module with 60 RPM in Dynamic-OsMBR system could enhance shear stress and reduce cake layer of foulants, leading to higher flux (50%) compared to Traditional-OsMBR during a 40-operation day. A negligible specific reverse salt flux (0.059 G/L) and a water flux of 2.86 LMH were recorded when a mixture of 0.1 M EDTA-2Na/0.1 M Na2CO3/0.9 mM Triton114 functioned as draw solution (DS). It was found that the Dynamic-OsMBR/NF hybrid system could effectively remove pollutants (∌98% COD, ∌99% PO43-P, ∌93% NH4+-N, > 99% suspended solids) from wastewater. In short, this developed system can be considered a breakthrough technology as it successfully minimizes membrane fouling by shear force, and achieves high water quality for reuse by two membrane- barriers

    Phase-dependent spectra in a driven two-level atom

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    We propose a method to observe phase-dependent spectra in resonance fluorescence, employing a two-level atom driven by a strong coherent field and a weak, amplitude-fluctuating field. The spectra are similar to those which occur in a squeezed vacuum, but avoid the problem of achieving squeezing over a 4π4\pi solid angle. The system shows other interesting features, such as pronounced gain without population inversion.Comment: 4 pages and 4 figures. Submitted to Phys. Rev. Let

    Effects of temperature and temperature gradient on concrete performance at elevated temperatures

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    To assure adequate fire performance of concrete structures, appropriate knowledge of and models for performance of concrete at elevated temperatures are crucial yet currently lacking, prompting further research. This article first highlights the limitations of inconsistent thermal boundary conditions in conventional fire testing and of using constitutive models developed based on empirical data obtained through testing concrete under minimised temperature gradients in modelling of concrete structures with significant temperature gradients. On that basis, this article outlines key features of a new test setup using radiant panels to ensure well-defined and reproducible thermal and mechanical loadings on concrete specimens. The good repeatability, consistency and uniformity of the thermal boundary conditions are demonstrated using measurements of heat flux and in-depth temperature of test specimens. The initial collected data appear to indicate that the compressive strength and failure mode of test specimens are influenced by both temperature and temperature gradient. More research is thus required to further quantify such effect and also to effectively account for it in rational performance-based fire design and analysis of concrete structures. The new test setup reported in this article, which enables reliable thermal/mechanical loadings and deformation capturing of concrete surface at elevated temperatures using digital image correlation, would be highly beneficial for such further research

    Anisotropy studies around the galactic centre at EeV energies with the Auger Observatory

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    Data from the Pierre Auger Observatory are analyzed to search for anisotropies near the direction of the Galactic Centre at EeV energies. The exposure of the surface array in this part of the sky is already significantly larger than that of the fore-runner experiments. Our results do not support previous findings of localized excesses in the AGASA and SUGAR data. We set an upper bound on a point-like flux of cosmic rays arriving from the Galactic Centre which excludes several scenarios predicting sources of EeV neutrons from Sagittarius AA. Also the events detected simultaneously by the surface and fluorescence detectors (the `hybrid' data set), which have better pointing accuracy but are less numerous than those of the surface array alone, do not show any significant localized excess from this direction.Comment: Matches published versio

    Realization of vertically aligned, ultra-high aspect ratio InAsSb nanowires on graphite

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    The monolithic integration of InAs1–xSbx semiconductor nanowires on graphitic substrates holds enormous promise for cost-effective, high-performance, and flexible devices in optoelectronics and high-speed electronics. However, the growth of InAs1–xSbx nanowires with high aspect ratio essential for device applications is extremely challenging due to Sb-induced suppression of axial growth and enhancement in radial growth. We report the realization of high quality, vertically aligned, nontapered and ultrahigh aspect ratio InAs1–xSbx nanowires with Sb composition (xSb(%)) up to ∌12% grown by indium-droplet assisted molecular beam epitaxy on graphite substrate. Low temperature photoluminescence measurements show that the InAs1–xSbx nanowires exhibit bright band-to-band related emission with a distinct redshift as a function of Sb composition providing further confirmation of successful Sb incorporation in as-grown nanowires. This study reveals that the graphite substrate is a more favorable platform for InAs1–xSbx nanowires that could lead to hybrid heterostructures possessing potential device applications in optoelectronics

    The type II RAF inhibitor tovorafenib in relapsed/refractory pediatric low-grade glioma: the phase 2 FIREFLY-1 trial

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    \ua9 2023, The Author(s).BRAF genomic alterations are the most common oncogenic drivers in pediatric low-grade glioma (pLGG). Arm 1 (n = 77) of the ongoing phase 2 FIREFLY-1 (PNOC026) trial investigated the efficacy of the oral, selective, central nervous system–penetrant, type II RAF inhibitor tovorafenib (420 mg m−2 once weekly; 600 mg maximum) in patients with BRAF-altered, relapsed/refractory pLGG. Arm 2 (n = 60) is an extension cohort, which provided treatment access for patients with RAF-altered pLGG after arm 1 closure. Based on independent review, according to Response Assessment in Neuro-Oncology High-Grade Glioma (RANO-HGG) criteria, the overall response rate (ORR) of 67% met the arm 1 prespecified primary endpoint; median duration of response (DOR) was 16.6 months; and median time to response (TTR) was 3.0 months (secondary endpoints). Other select arm 1 secondary endpoints included ORR, DOR and TTR as assessed by Response Assessment in Pediatric Neuro-Oncology Low-Grade Glioma (RAPNO) criteria and safety (assessed in all treated patients and the primary endpoint for arm 2, n = 137). The ORR according to RAPNO criteria (including minor responses) was 51%; median DOR was 13.8 months; and median TTR was 5.3 months. The most common treatment-related adverse events (TRAEs) were hair color changes (76%), elevated creatine phosphokinase (56%) and anemia (49%). Grade ≄3 TRAEs occurred in 42% of patients. Nine (7%) patients had TRAEs leading to discontinuation of tovorafenib. These data indicate that tovorafenib could be an effective therapy for BRAF-altered, relapsed/refractory pLGG. ClinicalTrials.gov registration: NCT04775485

    Applying advanced data analytics and machine learning to enhance the safety control of dams

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    The protection of critical engineering infrastructures is vital to today’s so- ciety, not only to ensure the maintenance of their services (e.g., water supply, energy production, transport), but also to avoid large-scale disasters. Therefore, technical and financial efforts are being continuously made to improve the safety control of large civil engineering structures like dams, bridges and nuclear facilities. This con- trol is based on the measurement of physical quantities that characterize the struc- tural behavior, such as displacements, strains and stresses. The analysis of monitor- ing data and its evaluation against physical and mathematical models is the strongest tool to assess the safety of the structural behavior. Commonly, dam specialists use multiple linear regression models to analyze the dam response, which is a well- known approach among dam engineers since the 1950s decade. Nowadays, the data acquisition paradigm is changing from a manual process, where measurements were taken with low frequency (e.g., on a weekly basis), to a fully automated process that allows much higher frequencies. This new paradigm escalates the potential of data analytics on top of monitoring data, but, on the other hand, increases data quality issues related to anomalies in the acquisition process. This chapter presents the full data lifecycle in the safety control of large-scale civil engineering infrastructures (focused on dams), from the data acquisition process, data processing and storage, data quality and outlier detection, and data analysis. A strong focus is made on the use of machine learning techniques for data analysis, where the common multiple linear regression analysis is compared with deep learning strategies, namely recur- rent neural networks. Demonstration scenarios are presented based on data obtained from monitoring systems of concrete dams under operation in Portugal.info:eu-repo/semantics/acceptedVersio
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