4,615 research outputs found

    Self-pulsation at 480 GHz from a two-color discrete mode laser diode

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    A discrete mode Fabry-PĂ©rot laser is designed and fabricated to achieve two-color lasing. We demonstrate beating between the two laser modes and self-pulsation at 480 GHz

    Inverse scattering approach to multiwavelength Fabry-PĂ©rot laser design

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    A class of multiwavelength Fabry-Pérot lasers is introduced where the spectrum is tailored through a patterning of the cavity effective index. The cavity geometry is obtained using an inverse scattering approach and can be designed such that the spacing of discrete Fabry-Pérot lasing modes is limited only by the bandwidth of the inverted gain medium. A specific two-color semiconductor laser with a mode spacing in the THz region is designed, and measurements are presented demonstrating the simultaneous oscillation of the two wavelengths. The nonperiodic effective index profile of the particular two-color device considered is shown to be related to a Moiré or superstructure grating

    In vivo cranial bone strain and bite force in the agamid lizard Uromastyx geyri

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    In vivo bone strain data are the most direct evidence of deformation and strain regimes in the vertebrate cranium during feeding and can provide important insights into skull morphology. Strain data have been collected during feeding across a wide range of mammals; in contrast, in vivo cranial bone strain data have been collected from few sauropsid taxa. Here we present bone strain data recorded from the jugal of the herbivorous agamid lizard Uromastyx geyri along with simultaneously recorded bite force. Principal and shear strain magnitudes in Uromastyx geyri were lower than cranial bone strains recorded in Alligator mississippiensis, but higher than those reported from herbivorous mammals. Our results suggest that variations in principal strain orientations in the facial skeleton are largely due to differences in feeding behavior and bite location, whereas food type has little impact on strain orientations. Furthermore, mean principal strain orientations differ between male and female Uromastyx during feeding, potentially because of sexual dimorphism in skull morphology

    Precise calibration of LIGO test mass actuators using photon radiation pressure

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    Precise calibration of kilometer-scale interferometric gravitational wave detectors is crucial for source localization and waveform reconstruction. A technique that uses the radiation pressure of a power-modulated auxiliary laser to induce calibrated displacements of one of the ~10 kg arm cavity mirrors, a so-called photon calibrator, has been demonstrated previously and has recently been implemented on the LIGO detectors. In this article, we discuss the inherent precision and accuracy of the LIGO photon calibrators and several improvements that have been developed to reduce the estimated voice coil actuator calibration uncertainties to less than 2 percent (1-sigma). These improvements include accounting for rotation-induced apparent length variations caused by interferometer and photon calibrator beam centering offsets, absolute laser power measurement using temperature-controlled InGaAs photodetectors mounted on integrating spheres and calibrated by NIST, minimizing errors induced by localized elastic deformation of the mirror surface by using a two-beam configuration with the photon calibrator beams symmetrically displaced about the center of the optic, and simultaneously actuating the test mass with voice coil actuators and the photon calibrator to minimize fluctuations caused by the changing interferometer response. The photon calibrator is able to operate in the most sensitive interferometer configuration, and is expected to become a primary calibration method for future gravitational wave searches.Comment: 13 pages, 6 figures, accepted by Classical and Quantum Gravit

    Precise calibration of LIGO test mass actuators using photon radiation pressure

    Full text link
    Precise calibration of kilometer-scale interferometric gravitational wave detectors is crucial for source localization and waveform reconstruction. A technique that uses the radiation pressure of a power-modulated auxiliary laser to induce calibrated displacements of one of the ~10 kg arm cavity mirrors, a so-called photon calibrator, has been demonstrated previously and has recently been implemented on the LIGO detectors. In this article, we discuss the inherent precision and accuracy of the LIGO photon calibrators and several improvements that have been developed to reduce the estimated voice coil actuator calibration uncertainties to less than 2 percent (1-sigma). These improvements include accounting for rotation-induced apparent length variations caused by interferometer and photon calibrator beam centering offsets, absolute laser power measurement using temperature-controlled InGaAs photodetectors mounted on integrating spheres and calibrated by NIST, minimizing errors induced by localized elastic deformation of the mirror surface by using a two-beam configuration with the photon calibrator beams symmetrically displaced about the center of the optic, and simultaneously actuating the test mass with voice coil actuators and the photon calibrator to minimize fluctuations caused by the changing interferometer response. The photon calibrator is able to operate in the most sensitive interferometer configuration, and is expected to become a primary calibration method for future gravitational wave searches.Comment: 13 pages, 6 figures, accepted by Classical and Quantum Gravit

    Machine Learning and Machine Vision Accelerate 3D Printed Orodispersible Film Development

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    Orodispersible films (ODFs) are an attractive delivery system for a myriad of clinical applications and possess both large economical and clinical rewards. However, the manufacturing of ODFs does not adhere to contemporary paradigms of personalised, on-demand medicine, nor sustainable manufacturing. To address these shortcomings, both three-dimensional (3D) printing and machine learning (ML) were employed to provide on-demand manufacturing and quality control checks of ODFs. Direct ink writing (DIW) was able to fabricate complex ODF shapes, with thicknesses of less than 100 ”m. ML algorithms were explored to classify the ODFs according to their active ingredient, by using their near-infrared (NIR) spectrums. A supervised model of linear discriminant analysis was found to provide 100% accuracy in classifying ODFs. A subsequent partial least square algorithm was applied to verify the dose, where a coefficient of determination of 0.96, 0.99 and 0.98 was obtained for ODFs of paracetamol, caffeine, and theophylline, respectively. Therefore, it was concluded that the combination of 3D printing, NIR and ML can result in a rapid production and verification of ODFs. Additionally, a machine vision tool was used to automate the in vitro testing. These collective digital technologies demonstrate the potential to automate the ODF workflow

    Flavone acetic acid (FAA) with recombinant interleukin-2 (rIL-2) in advanced malignant melanoma. III: Cytokine studies.

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    Twelve patients undergoing IL-2 and flavone acetic acid (FAA) combination immunotherapy for advanced melanoma were studied throughout treatment for the induction of measurable levels of bioactive TNF, GM-CSF and IL-6 in their serum. This was to assess the extent of secondary cytokine induction in these patients and the possible role of such cytokines in both the toxic and therapeutic responses. The nature of the treatment schedule enabled these cytokines to be measured in response to FAA alone, FAA/IL-2 and FAA alone following IL-2/FAA activation of target cells. A small rise in the serum levels of these cytokines was seen on the initial course of FAA/IL-2 but this was minor compared to the marked elevation in levels 2-8 h following the initiation of the third course of FAA given with or without IL-2 and at a time point which coincided with maximum toxicity in those patients who experienced it. These results show that FAA alone can induce cytokine release from primed target cells. This may be associated with the therapeutic effect and/or toxicity of the agent

    Melt Conditioned Direct Chill Casting (MC-DC) Process for Production of High Quality Aluminium Alloy Billets

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    A novel direct chill (DC) casting process, melt conditioned direct chill (MC-DC) casting process, has been developed for production of high quality aluminium alloy billets. In the MC-DC casting process, a high shear device is submerged in the sump of the DC mould to provide intensive melt shearing, which in turn, disperses potential nucleating particles, creates a macroscopic melt flow to uniformly distribute the dispersed particles, and maintains a uniform temperature and chemical composition throughout the melt in the sump. Experimental results have demonstrated that, the MC-DC casting process can produce aluminium alloy billets with significantly refined microstructure and reduced cast defects. In this paper, we give an overview of the MC-DC casting process and report on results obtained from an industrial scale trial
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