1,189 research outputs found

    The 230230 GHz Variability of Numerical Models of Sagittarius~A* I. Parameter Surveys on Varying Ion-electron Temperature Ratios Under Strongly Magnetized Conditions

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    The 230230 GHz lightcurves of Sagittarius~A* (Sgr~A*) predicted by general relativistic magnetohydrodynamics (GRMHD) and ray-tracing (GRRT) models in Event Horizon Telescope Collaboration et al. (2022) have higher variability MΔTM_{\Delta T} compared to observations. In this series of papers, we explore the origin of such large brightness variability. In this first paper, we performed large GRRT parameter surveys that span from the optically thin to the optically thick regimes, covering the ion-electron temperature ratio under strongly magnetized conditions, RLowR_{\rm Low}, from 11 to 6060. We find that increasing RLowR_{\rm Low} can lead to either an increase or a reduction in MΔTM_{\Delta T} depending on other model parameters, making it consistent with the observed variability of Sgr~A* in some cases. Our analysis of GRRT image snapshots finds that the major contribution to the large MΔTM_{\Delta T} for the RLow=1R_{\rm Low} = 1 models comes from the photon rings. However, secondary contributions from the accretion flow are also visible depending on the spin parameter. Our work demonstrates the importance of the electron temperature used for modelling radiatively inefficient accretion flows and places new constraints on the ion-electron temperature ratio. A more in-depth analysis for understanding the dependencies of MΔTM_{\Delta T} on RLowR_{\rm Low} will be performed in subsequent papers.Comment: 15 Pages, 9 Figure

    Ocular manifestations and pathology of adult T-cell leukemia/lymphoma associated with human T-lymphotropic virus type 1

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    The human T-cell lymphotropic virus type 1 (HTLV-1), endemic in defined geographical areas around the world, is recognized as the etiologic agent of adult T-cell leukemia/lymphoma (ATL), or HTLV-1. ATL is a rare adult onset T-cell malignancy that is characterized by the presence of ATL flower cells with T-cell markers, HTLV-1 antibodies in the serum, and monoclonal integration of HTLV-1 provirus in affected cells. Ocular manifestations associated with HTLV-1 virus infection have been reported and include HTLV-1 uveitis and keratoconjunctivitis sicca, but reports of ocular involvement in ATL are exceedingly rare. This article describes the ocular manifestations and pathology of ATL. We also report for the first time a case of a 34-year-old male with systemic ATL and prominent atypical lymphoid cell infiltration in the choroid. To our knowledge, this is the first report defining prominent choroidal involvement as a distinct ocular manifestation of ATL. ATL may masquerade as a variety of other conditions, and molecular techniques involving microdissection and PCR have proven to be critical diagnostic tools. International collaboration will be needed to better understand the presentation and diagnosis of this rare malignancy

    Autoimmune Retinopathy in Systemic Lupus Erythematosus: Histopathologic Features

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    The ocular pathology of autoimmune retinopathy is demonstrated in a 62-year-old female patient with systemic lupus erythematosus (SLE) who presented with typical clinical autoimmune retinopathy. Macroscopically, there were multiple depigmented lesions in the peripheral retina and choroid and scattered pigmentary bone-spickling at the equator and periphery. Microscopically, there were generalized loss of photoreceptors and thinning of the outer plexiform layer. Many peripheral retinal vessels were sclerotic and occluded, some surrounded by pigment granules and RPE cells. Cobblestone degeneration was prominent in the periphery. Macrophages were seen in the retina, particularly in areas of photoreceptor degeneration. Rare, scattered T- lymphocytes were present in the retina and choroid, while B-cells were notably absent. The optic nerve showed loss of axons and thickened septae. Serum autoantibodies against normal retinal nuclei were detected. These pathological changes represent both known SLE-associated ocular complications as well as possible features of autoimmune retinopathy secondary to SLE

    Autoimmune Retinopathy in Systemic Lupus Erythematosus: Histopathologic Features

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    The ocular pathology of autoimmune retinopathy is demonstrated in a 62-year-old female patient with systemic lupus erythematosus (SLE) who presented with typical clinical autoimmune retinopathy. Macroscopically, there were multiple depigmented lesions in the peripheral retina and choroid and scattered pigmentary bone-spickling at the equator and periphery. Microscopically, there were generalized loss of photoreceptors and thinning of the outer plexiform layer. Many peripheral retinal vessels were sclerotic and occluded, some surrounded by pigment granules and RPE cells. Cobblestone degeneration was prominent in the periphery. Macrophages were seen in the retina, particularly in areas of photoreceptor degeneration. Rare, scattered T- lymphocytes were present in the retina and choroid, while B-cells were notably absent. The optic nerve showed loss of axons and thickened septae. Serum autoantibodies against normal retinal nuclei were detected. These pathological changes represent both known SLE-associated ocular complications as well as possible features of autoimmune retinopathy secondary to SLE

    Mahakala: a Python-based Modular Ray-tracing and Radiative Transfer Algorithm for Curved Space-times

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    We introduce Mahakala, a Python-based, modular, radiative ray-tracing code for curved space-times. We employ Google's JAX framework for accelerated automatic differentiation, which can efficiently compute Christoffel symbols directly from the metric, allowing the user to easily and quickly simulate photon trajectories through non-Kerr metrics. JAX also enables Mahakala to run in parallel on both CPUs and GPUs and achieve speeds comparable to C-based codes. Mahakala natively uses the Cartesian Kerr-Schild coordinate system, which avoids numerical issues caused by the "pole" of spherical coordinates. We demonstrate Mahakala's capabilities by simulating the 1.3 mm wavelength images (the wavelength of Event Horizon Telescope observations) of general relativistic magnetohydrodynamic simulations of low-accretion rate supermassive black holes. The modular nature of Mahakala allows us to easily quantify the relative contribution of different regions of the flow to image features. We show that most of the emission seen in 1.3 mm images originates close to the black hole. We also quantify the relative contribution of the disk, forward jet, and counter jet to 1.3 mm images.Comment: 15 pages, 11 figure

    Mars Science Helicopter Conceptual Design

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    Robotic planetary aerial vehicles increase the range of terrain that can be examined, compared to traditional landers and rovers, and have more near-surface capability than orbiters. Aerial mobility is a promising possibility for planetary exploration as it reduces the challenges that difficult obstacles pose to ground vehicles. The first use of a rotorcraft for a planetary mission will be in 2021, when the Mars Helicopter technology demonstrator will be deployed from the Mars 2020 rover. The Jet Propulsion Laboratory and NASA Ames Research Center are exploring possibilities for a Mars Science Helicopter, a second-generation Mars rotorcraft with the capability of conducting science investigations independently of a lander or rover (although this type of vehicle could also be used assist rovers or landers in future missions). This report describes the conceptual design of Mars Science Helicopters. The design process began with coaxial-helicopter and hexacopter configurations, with a payload in the range of two to three kilograms and an overall vehicle mass of approximately twenty kilograms. Initial estimates of weight and performance were based on the capabilities of the Mars Helicopter. Rotorcraft designs for Mars are constrained by the dimensions of the aeroshell for the trip to the planet, requiring attention to the aircraft packaging in order to maximize the rotor dimensions and hence overall performance potential. Aerodynamic performance optimization was conducted, particularly through airfoils designed specifically for the low Reynolds number and high Mach number inherent in operation on Mars. The final designs show a substantial capability for science operations on Mars: a 31 kg hexacopter that fits within a 2.5 m diameter aeroshell could carry a 5 kg payload for 10 min of hover time or over a range of 5 km

    Desperate housewives: An analysis of the characterisations of female gamblers portrayed in gambling movies in Hong Kong

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    This article examines portrayals of female gamblers in recent Hong Kong movies. The authors report that the depiction of female gamblers is very different from that of male gamblers in the movies made in the same period. Whereas the male gamblers are pitching a lonely and desperate battle against the evil opponent, the female gamblers portrayed in the movies are housewives or small-time players who gamble only for their personal gain. A general negative overtone in portrayals of female gamblers was interpreted as a reflection of the traditional view that discourages women from gambling. The shift of gambling themes in the Hong Kong movies has been identified to reflect the most salient concerns among Hong Kong residents. Such changes are attributed to particular social and cultural changes in the community
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