We analyze eight XMM-Newton observations of the bright Narrow Line Seyfert 1 galaxy Arakelian 564（Ark 564）. These observations, separated bye^6 days, allow us to look for correlations between the simultaneous ultrav...We analyze eight XMM-Newton observations of the bright Narrow Line Seyfert 1 galaxy Arakelian 564（Ark 564）. These observations, separated bye^6 days, allow us to look for correlations between the simultaneous ultraviolet（UV） emission（from th Optical Monitor） with not only the X-ray flux but also with different X-ray spectral parameters. The X-ray spectra from all the observations are found to be adequately fitted by a double Comptonization model where the soft excess and the hard X-ray power law are represented by thermal Comptonization in a low temperature plasma and hot corona, respectively. Apart from the fluxes of each component, the hard X-ray power law index is found to be variable. These results suggest that the variability is associated with changes in the geometry of the inner region. The UV emission is found to be variable and well correlated with the high energy index while the correlations with the fluxes of each component are found to be weaker. Using viscous timescale arguments we rule out the possibility that the UV variation is due to the fluctuating accretion rate in the outer disk. If the UV variation is driven by X-ray reprocessing, then our results indicate that the strength of the X-ray reprocessing depends more on the geometry of the X-ray producing inner region rather than on the X-ray luminosity alone.展开更多
In this paper we initiate a study of covariance and variance for two operators on a Hilbert space. proving that the c-v (covariance-variance) inequality holds, which is equivalent to the Cauchy- Schwarz inequality. As...In this paper we initiate a study of covariance and variance for two operators on a Hilbert space. proving that the c-v (covariance-variance) inequality holds, which is equivalent to the Cauchy- Schwarz inequality. As for applications of the c-v inequality we provc uniformly the Bernstein-type inequalities and equalities. and show the generalized Heinz-Kato-Furuta-type inequalities and equalities. from which a generalization and sharpening of Reid’s inequlality is obtained. We show that every operator can be expressed as a p-hyponormal-type, and a hyponormal-type operator. Finally, some new characterizations of the Furuta inequality are given.展开更多
Among the challenges of poststructuralist thought has been the demand that we acknowledge a kind of philosophical emptiness which many feel accompanies the perceived decline in foundationalist thought. By looking more...Among the challenges of poststructuralist thought has been the demand that we acknowledge a kind of philosophical emptiness which many feel accompanies the perceived decline in foundationalist thought. By looking more closely at Barthes and Baudrillard＇s writing on meaning, writing, language, truth, and the real, we can come to a better understanding of the emergence and implications of the poststructural challenge. The paper argues that Barthes＇ and Baudrillard＇s writing on these five key concepts can lead us to a more liberating conception of thought and contribute to our individual effort to become more challenging thinkers. This paper also （unavoidably） points to several points of convergence and divergence between Barthes and Baudrillard.展开更多
基金based on observations obtained with the XMM-Newton satellite,an ESA science mission with instruments and contributions directly funded by ESA Member States and the USA(NASA)made use of the NASA/IPAC Extragalactic Data base which is operated by the Jet Propulsion Laboratory,California Institute of Technology and data obtained through the High Energy Astrophysics Science Archive Research Center Online Service,provided by NASA/GSFCthe Department of Science and Technology of India for the grant(No.SR/S2/HEP-07/2012)that supported this work
文摘We analyze eight XMM-Newton observations of the bright Narrow Line Seyfert 1 galaxy Arakelian 564（Ark 564）. These observations, separated bye^6 days, allow us to look for correlations between the simultaneous ultraviolet（UV） emission（from th Optical Monitor） with not only the X-ray flux but also with different X-ray spectral parameters. The X-ray spectra from all the observations are found to be adequately fitted by a double Comptonization model where the soft excess and the hard X-ray power law are represented by thermal Comptonization in a low temperature plasma and hot corona, respectively. Apart from the fluxes of each component, the hard X-ray power law index is found to be variable. These results suggest that the variability is associated with changes in the geometry of the inner region. The UV emission is found to be variable and well correlated with the high energy index while the correlations with the fluxes of each component are found to be weaker. Using viscous timescale arguments we rule out the possibility that the UV variation is due to the fluctuating accretion rate in the outer disk. If the UV variation is driven by X-ray reprocessing, then our results indicate that the strength of the X-ray reprocessing depends more on the geometry of the X-ray producing inner region rather than on the X-ray luminosity alone.
文摘In this paper we initiate a study of covariance and variance for two operators on a Hilbert space. proving that the c-v (covariance-variance) inequality holds, which is equivalent to the Cauchy- Schwarz inequality. As for applications of the c-v inequality we provc uniformly the Bernstein-type inequalities and equalities. and show the generalized Heinz-Kato-Furuta-type inequalities and equalities. from which a generalization and sharpening of Reid’s inequlality is obtained. We show that every operator can be expressed as a p-hyponormal-type, and a hyponormal-type operator. Finally, some new characterizations of the Furuta inequality are given.
文摘Among the challenges of poststructuralist thought has been the demand that we acknowledge a kind of philosophical emptiness which many feel accompanies the perceived decline in foundationalist thought. By looking more closely at Barthes and Baudrillard＇s writing on meaning, writing, language, truth, and the real, we can come to a better understanding of the emergence and implications of the poststructural challenge. The paper argues that Barthes＇ and Baudrillard＇s writing on these five key concepts can lead us to a more liberating conception of thought and contribute to our individual effort to become more challenging thinkers. This paper also （unavoidably） points to several points of convergence and divergence between Barthes and Baudrillard.
