122,531 research outputs found

    AI for public health: Self-screening for eye diseases

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    A software-based visual-field testing (perimetry) system is described which incorporates several AI components, including machine learning, an intelligent user interface and pattern discovery. This system has been successfully used for self-screening in several different public environment

    Asteroseismology of the δ\delta Scuti star HD 50844

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    Aims. We aim to probe the internal structure and investigate more detailed information of the δ\delta Scuti star HD 50844 with asteroseismology. Methods. We analyse the observed frequencies of the δ\delta Scuti star HD 50844 obtained by Balona (2014), and search for possible multiplets based on the rotational splitting law of g-mode. We tried to disentangle the frequency spectra of HD 50844 by means of the rotational splitting only. We then compare them with theoretical pulsation modes, which correspond to stellar evolutionary models with various sets of initial metallicity and stellar mass, to find the best-fitting model. Results. There are three multiplets including two complete triplets and one incomplete quintuplet, in which mode identifications for spherical harmonic degree ll and azimuthal number mm are unique. The corresponding rotational period of HD 50844 is found to be 2.440.08+0.13^{+0.13}_{-0.08} days. The physical parameters of HD 50844 are well limited in a small region by three modes identified as nonradial ones (f11f_{11}, f22f_{22}, and f29f_{29}) and by the fundamental radial mode (f4f_{4}). Our results show that the three nonradial modes (f11f_{11}, f22f_{22}, and f29f_{29}) are all mixed modes, which mainly represent the property of the helium core. The fundamental radial mode (f4f_{4}) mainly represents the property of the stellar envelope. In order to fit these four pulsation modes, both the helium core and the stellar envelope must be matched to the actual structure of HD 50844. Finally, the mass of the helium core of HD 50844 is estimated to be 0.173 ±\pm 0.004 MM_{\odot} for the first time. The physical parameters of HD 50844 are determined to be M=M= 1.81 ±\pm 0.01 MM_{\odot}, Z=Z= 0.008 ±\pm 0.001. Teff=T_{\rm eff}= 7508 ±\pm 125 K, logg=g= 3.658 ±\pm 0.004, R=R= 3.300 ±\pm 0.023 RR_{\odot}, L=L= 30.98 ±\pm 2.39 LL_{\odot}.Comment: 11 pages, 7 figures, 6 tables, accepted for publication in A&
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