6,749 research outputs found
Mollusca of the Illinois River, Arkansas
The Illinois River is in the Ozark region of northwestern Arkansas and eastern Oklahoma. A survey of the Illinois River in Arkansas produced nine species and one morphological subspecies of gastropods, three species of sphaeriid clams, and 23 species of unionid mussels. Museum records resulted in another two species and an ecophenotype of the Unionidae. This represents the first published survey of molluscan species from the Illinois River in Arkansas
Observations of Outflowing UV Absorbers in NGC 4051 with the Cosmic Origins Spectrograph
We present new Hubble Space Telescope (HST)/Cosmic Origins Spectrograph
observations of the Narrow-Line Seyfert 1 galaxy NGC 4051. These data were
obtained as part of a coordinated observing program including X-ray
observations with the Chandra/High Energy Transmission Grating (HETG)
Spectrometer and Suzaku. We detected nine kinematic components of UV
absorption, which were previously identified using the HST/Space Telescope
Imaging Spectrograph. None of the absorption components showed evidence for
changes in column density or profile within the \sim 10 yr between the STIS and
COS observations, which we interpret as evidence of 1) saturation, for the
stronger components, or 2) very low densities, i.e., n_H < 1 cm^-3, for the
weaker components. After applying a +200 km s^-1 offset to the HETG spectrum,
we found that the radial velocities of the UV absorbers lay within the O VII
profile. Based on photoionization models, we suggest that, while UV components
2, 5 and 7 produce significant O VII absorption, the bulk of the X-ray
absorption detected in the HETG analysis occurs in more highly ionized gas.
Moreover, the mass loss rate is dominated by high ionization gas which lacks a
significant UV footprint.Comment: 41 pages, 10 Figures; accepted for publication in the Astrophysical
Journa
Generalized Entropies
We study an entropy measure for quantum systems that generalizes the von
Neumann entropy as well as its classical counterpart, the Gibbs or Shannon
entropy. The entropy measure is based on hypothesis testing and has an elegant
formulation as a semidefinite program, a type of convex optimization. After
establishing a few basic properties, we prove upper and lower bounds in terms
of the smooth entropies, a family of entropy measures that is used to
characterize a wide range of operational quantities. From the formulation as a
semidefinite program, we also prove a result on decomposition of hypothesis
tests, which leads to a chain rule for the entropy.Comment: 21 page
The Variable X-ray Spectrum of Markarian 766 - II. Time-Resolved Spectroscopy
CONTEXT: The variable X-ray spectra of AGN systematically show steep
power-law high states and hard-spectrum low states. The hard low state has
previously been found to be a component with only weak variability. The origin
of this component and the relative importance of effects such as absorption and
relativistic blurring are currently not clear. AIMS: In a follow-up of previous
principal components analysis, we aim to determine the relative importance of
scattering and absorption effects on the time-varying X-ray spectrum of the
narrow-line Seyfert 1 galaxy Mrk~766. METHODS: Time-resolved spectroscopy,
slicing XMM and Suzaku data down to 25 ks elements, is used to investigate
whether absorption or scattering components dominate the spectral variations in
Mrk 766.Time-resolved spectroscopy confirms that spectral variability in Mrk
766 can be explained by either of two interpretations of principal components
analysis. Detailed investigation confirm rapid changes in the relative
strengths of scattered and direct emission or rapid changes in absorber
covering fraction provide good explanations of most of the spectral
variability. However, a strong correlation between the 6.97 keV absorption line
and the primary continuum together with rapid opacity changes show that
variations in a complex and multi-layered absorber, most likely a disk wind,
are the dominant source of spectral variability in Mrk 76
Computer processing support, volume 4
There are no author-identified significant results in this report
Globalization and E-Commerce III. The French Enviroment and Policy
According to most indicators, the use of the Internet and the development of e-commerce (over the Internet) in France are below the level that should be reached given the French level of development. This observation can be explained by the late adoption of digital technologies by the French. However, the French lateness is less important for professional uses than for domestic uses. France began to catch up with pioneering countries during 1999-2000, but the collapse Internet bubble reduced the pace of adoption. The French late adoption of digital technologies is partly the result of the strong involvement of France in the development of two pre-existing technologies: Minitel (principally dedicated to B2C) and EDI (dedicated to B2B). Both technologies provided the users with a sufficient level of service to support their business processes, but hindered their propensity to switch to new Internet-based technology. Consequently, most available indicators underestimate the actual level of e-commerce in France, especially the French business readiness to switching to Web-based commerce. The late adoption of technology was not the only inhibitor for e-commerce. In France\u27s recent economic history, decision makers focused for too long on other issues. France had to adapt its economy and its industry to a competitive and global environment. Since the State played a strong role in an economy that was not widely open to competition, a wide set of reforms took place between the mid-1980s and the late 1990s. However, this restructuring policy prepared France for the adoption of e-commerce. as France was transformed into a service economy. Most organizations became more flexible by externalizing non-core activities and by implementing modular principles of organization. French companies went international as well. This new business climate favored the adoption of e-business and e-commerce practice by the end of the 1990s. When macroeconomic and industrial restructurings were achieved, the French government launched a strong information society policy. Since 1998, the government furthered the deregulation of telecommunication services, reshaped the legal framework to adapt to digital technologies, promoted IT training and innovation, and developed e-government. These policies were both a component of and aligned with the year 2000 e-Europe initiative of the European Union (EU), which promoted the development of a strong digital economy. Specific support programs (in RD and development of content) were combined and an intensive effort for legislation and inter-member benchmarking occurred (to stimulate member states to align on the most advanced state), the Commission and the Council of the EU tried try to stimulate development of a dynamic digital industry in Europe, and to boost the adoption of digital technologies and the new-methods of work and business enabled by them. While the European and the French policies impacted the adoption of digital technologies and e-commerce development significantly, they were insufficient to really enable France to catch up. The bursting of the Internet bubble slowed the pace. Moreover, B2C e-commerce was inhibited by the efficiency of the French distribution system that serves at a low cost alternative to the Internet for most of the population. The existing installed base of EDI, especially in the automobile and distribution industries, inhibits B2B e-commerce over the Internet. Consequently, the French e-commerce path of development is unique since it relies less on the Internet than in many other countries. Despite these inhibitors, France is adopting digital technologies and related practices at a higher pace than the other European countries. Within France, e-commerce is quite different in the various regions and industries. The Paris area (one-fifth of the French population), the IT industry, the professional services and distribution industries, and large companies are as intensively digitized as most advanced countries, industries, and companies worldwide. H
The Political Character of Computing Developments: Citizens\u27 interests and Government Services
This paper focuses on how citizens\u27 interests are dealt with and mediated by means of computer technology. It examines the distribution of computing resources to different government activities and, indirectly, to different client groups. It asks to what extent the patterns of computer use reflect stable patterns of choice favoring some uses over others and, therefore, some client groups over others. Two political perspectives on the patterns of choice are considered: managerial rationalism and reinforcement politics. To the extent that managerial rationalism characterizes computing decisions, we would expect to see computing distributed in favor of these government activities that provide direct services to citizens, and that actually expand, rather than contract, the array of choices available to citizens. In contrast, to the extent that reinforcement politics characterizes computing decisions, we would expect to see computing used in support of routine administrative activities, basic local government services, bureaucratic control over government departments and agencies, and social control over the recipients of social services such as welfare, health, and recreation. To examine which of these perspectives best characterizes computing in public organizations, we examine the portfolios of investment in computer based applications, using data collected from over 700 city and county governments in the United States. First, we look at the extent to which computing is applied to different local government functions. This examination suggests that computing tends to reinforce the traditional emphases of local governments towar
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