703,707 research outputs found
Gravitational Redshift of Emission Lines in the AGN Spectra
The detection of gravitationally redshifted optical emission lines has been
reported just for a few active galaxies. In this paper we give a short overview
of studies that analyzed or exploited the detection of the gravitational
redshift in optical AGN spectra. In addition, we tested the consistency of
gravitational redshift as the physical origin of the redward shifts observed in
their spectra using a sample of 50 Hamburg-ESO intermediate to high
redshift quasars that are among the most luminous quasars known ( erg/s), and are expected to host very massive
black holes. To this aim we modeled the line profile with accretion disk models
around a black hole.Comment: 10 pages, 2 figures, 3 table
Space, territory, and a stupa in Eastern Nepal: exploring Himalayan themes and traces of Bon
Recent research has adduced growing evidence for a distinct stratum of cultural practices that underlies various "tribal" traditions in the Himalayan region and that also seems to be characteristic of various local versions of the Bon tradition. Bon literature is not uncommonly embedded in cultural patterns that are more specifically Himalayan than belonging to the greater South Asian heritage. Two aspects of this that have received attention in Ramble's (1997) study of a Bon guide to the sacred Kong-po mountain (rKong-po bon- ri) are the symbolism of wild boar hunting involved in marriage rituals and poison cults with their corresponding beliefs about poisoning. Another pattern of cultoral organization that may help better understand the Bon tradition against its Himalayan background is spatial conceptualization
The relationship between price volatility, maturity and volume of trade of the Malaysian bond market
Kajian ini cuba membuat eksplorasi ke atas kesan tempoh matang dan volum dagangan ke atas kemeruapan pasaran bon Malaysia. Bon MGS, Cagamas clan Korporat yang aktif didagangkan merupakan data yang digunakan di dalam kajian ini. Perhubungan di antara pembolehubah-pembolehubah ini seterusnya dicerap dengan menggunakan analisa regresi. Tempoh kajian ini dibahagikan kepada tiga tempoh iaitu tempoh krisis (Mac 1996-Jun I997), tempoh semasa krisis sebelum pegging (Julai 1997-Ogos 1998) dan tempoh krisis selepas pegging (September 1998-Mac 1999). Adalah didapati bahawa tidak wujud perhubungan di antara kemeruapan harga dan tempoh matang bagi bon MGS dan Cagamas tetapi bagi bon Korporat, perhubungan di antara pemboleh ubah tersebut adalah positif dalam semua tempoh masa. Keputusan kajian juga menunjukkan bagi bon Korporat apabila volum dagangan dimasukkan ke dalam persamaan regresi, perhubungan di antara tempoh matang dan kemeruapan harganya menjadi tidak signifikan kecuali bagi tempoh semasa krisis sebelum pegging
A 2 degree-of-freedom SOI-MEMS translation stage with closed loop positioning
This research contains the design, analysis, fabrication, and characterization of a closed loop XY micro positioning stage. The XY micro positioning stage is developed by adapting parallel-kinematic mechanisms, which have been widely used for macro and meso scale positioning systems, to silicon-based micropositioner. Two orthogonal electrostatic comb drives are connected to moving table through 4-bar mechanism and independent hinges which restrict unwanted rotation in 2-degree-of-freedom translational stage. The XY micro positioning stage is fabricated on SOI wafer with three photolithography patterning processes followed by series of DRIE etching and HF etching to remove buried oxide layer to release the end-effector of the device. The fabricated XY micro positioning stage is shown in Fig1 with SEM images. The device provides a motion range of 20 microns in each direction at the driving voltage of 100V. The resonant frequency of the XY stage under ambient conditions is 811 Hz with a high quality factor of 40 achieved from parallel kinematics. The positioning loop is closed using a COTS capacitance-to-voltage conversion IC and a PID controller built in D-space is used to control position with an uncertainty characterized by a standard distribution of 5.24nm and a approximate closed-loop bandwidth of 27Hz. With the positioning loop, the rise time and settling time for closed-loop system are 50ms and 100ms. With sinusoidal input of ω=1Hz, the maximum phase difference of 108nm from reference input is obtained with total motion range of 8μm
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