15,299 research outputs found

    3D high definition video coding on a GPU-based heterogeneous system

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    H.264/MVC is a standard for supporting the sensation of 3D, based on coding from 2 (stereo) to N views. H.264/MVC adopts many coding options inherited from single view H.264/AVC, and thus its complexity is even higher, mainly because the number of processing views is higher. In this manuscript, we aim at an efficient parallelization of the most computationally intensive video encoding module for stereo sequences. In particular, inter prediction and its collaborative execution on a heterogeneous platform. The proposal is based on an efficient dynamic load balancing algorithm and on breaking encoding dependencies. Experimental results demonstrate the proposed algorithm's ability to reduce the encoding time for different stereo high definition sequences. Speed-up values of up to 90× were obtained when compared with the reference encoder on the same platform. Moreover, the proposed algorithm also provides a more energy-efficient approach and hence requires less energy than the sequential reference algorith

    High spatial resolution and high contrast optical speckle imaging with FASTCAM at the ORM

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    In this paper, we present an original observational approach, which combines, for the first time, traditional speckle imaging with image post-processing to obtain in the optical domain diffraction-limited images with high contrast (1e-5) within 0.5 to 2 arcseconds around a bright star. The post-processing step is based on wavelet filtering an has analogy with edge enhancement and high-pass filtering. Our I-band on-sky results with the 2.5-m Nordic Telescope (NOT) and the lucky imaging instrument FASTCAM show that we are able to detect L-type brown dwarf companions around a solar-type star with a contrast DI~12 at 2" and with no use of any coronographic capability, which greatly simplifies the instrumental and hardware approach. This object has been detected from the ground in J and H bands so far only with AO-assisted 8-10 m class telescopes (Gemini, Keck), although more recently detected with small-class telescopes in the K band. Discussing the advantage and disadvantage of the optical regime for the detection of faint intrinsic fluxes close to bright stars, we develop some perspectives for other fields, including the study of dense cores in globular clusters. To the best of our knowledge this is the first time that high contrast considerations are included in optical speckle imaging approach.Comment: Proceedings of SPIE conference - Ground-based and Airborne Instrumentation for Astronomy III (Conference 7735), San Diego 201

    Silicon-on-insulator shortwave infrared wavelength meter with integrated photodiodes for on-chip laser monitoring

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    This paper demonstrates a very compact wavelength meter for on-chip laser monitoring in the shortwave infrared wavelength range based on an optimized arrayed waveguide grating (AWG) filter with an integrated photodiode array. The AWG response is designed to obtain large nearest neighbor crosstalk (i. e. large overlap) between output channels, which allows accurately measuring the wavelength of a laser under test using the centroid detection technique. The passive AWG is fabricated on a 220 nm silicon-on-insulator (SOI) platform and is combined with GaInAsSb-based photodiodes. The photodiodes are heterogeneously integrated on the output grating couplers of the AWG using DVS-BCB adhesive bonding. The complete device with AWG and detectors has a footprint of only 2 mm(2) while the measured accuracy and resolution of the detected wavelength is better than 20pm. (C)2014 Optical Society of Americ

    Warps and correlations with intrinsic parameters of galaxies in the visible and radio

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    From a comparison of the different parameters of warped galaxies in the radio, and especially in the visible, we find that: a) No large galaxy (large mass or radius) has been found to have high amplitude in the warp, and there is no correlation of size/mass with the degree of asymmetry of the warp. b) The disc density and the ratio of dark to luminous mass show an opposing trend: smaller values give more asymmetric warps in the inner radii (optical warps) but show no correlation with the amplitude of the warp; however, in the external radii neither is there any correlation with the asymmetry. c) A third anticorrelation arises from a comparison of the amplitude and degree of asymmetry in the warped galaxies. Hence, it seems that very massive dark matter haloes have nothing to do with the formation of warps but only with the degree of symmetry in the inner radii, and are unrelated to the warp shape for the outermost radii. Denser discs show up the same dependence.Comment: 13 pages, 2 figures, accepted to be published in A&

    Interrupting the Axis: A Case of IgG-4 Related Hypophysitis in a Young Hispanic Male

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    Background: Hypophysitis refers to inflammation of the pituitary gland that can lead to the disruption of the hypothalamic-pituitary-adrenal axis. Primary hypophysitis has five variants differentiated by histologic findings: lymphocytic, granulomatous, xanthomatous, IgG4-related, and necrotizing. IgG4-related hypophysitis is very rare and is commonly a manifestation of a multi-organ systemic disorder. We present a case of a 43-year-old man presenting with severe headache and symptomatic hyponatremia in the setting of isolated IgG-4 related hypophysitis. Case Presentation: A 43-year-old male presented with a two-day history of severe posterior headache associated with several episodes of vomiting, photophobia, generalized weakness and fatigue. Patient had no history of headaches and denied any recent trauma, focal weakness, altered mentation, changes in vision or seizure activity. Vitals on admission were remarkable for BP 179/99 mmHg. Neurological examination was non-focal, cranial nerves were grossly intact. Labs showed unremarkable CBC, sodium 117 mmol/L, potassium 3.3 mmol/L, chloride 84 mmol/L, glucose 244 mg/d, TSH 0.6 uIU/mL, cortisol 4.6 ug/dL, urine osmolality 540, serum osmolality 259 and prolactin level 7.8. CT head without contrast showed a mass-like enlargement of the Sella measuring 1.6 cm x 1.4 cm suspicious for macroadenoma. Patient was started on hypertonic saline, fludrocortisone, hydrocortisone, and salt tablets in the setting of suspected macroadenoma. Once the patient was stabilized, he underwent transsphenoidal resection of pituitary lesion. Pathology of the lesion showed a small area rich in plasma cells with positive IgG4 immunostaining in most of the plasma cells, consistent with IgG4-related pituitary hypophysitis. Conclusion: IgG4 hypophysitis usually presents in a context of multiple organ IgG4 involvement, however isolated hypophysitis has been reported. The patients present with mass effect symptoms and/or anterior hypopituitarism. When histologic diagnosis is obtained via biopsy, IgG4 hypophysitis can be managed exclusively with corticosteroids
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