UV Continuum, Physical Conditions and Filling Factor in Active Galactic Nuclei

The narrow line region of active galaxies is formed by gas clouds surrounded by a diluted gas. Standard one-dimensional photoionization models are usually used to model this region in order to reproduce the observed emission lines. Since the narrow line region is not homogeneous, two major types of models are used: (a) those assuming a homogeneous gas distribution and a filling factor less than unity to mimic the presence of the emitting clouds; (b) those based on a composition of single-cloud models combined in order to obtain the observed spectra. The first method is largely used but may induce to misleading conclusions as shown in this paper. The second one is more appropriate, but requires a large number of observed lines in order to limit the number of single models used. After discussing the case of an extragalactic HII region, for which the ionizing radiation spectrum is better known, we show that 1-D models for the narrow line region with a filling factor less than unit do not properly mimic the clumpiness, but just simulates an overall lower density. Multi-cloud models lead to more reliable results. Both models are tested in this paper, using the emission-line spectra of two well-known Seyfert galaxies, NGC 4151 and NGC 1068. It is shown that ionizing radiation spectra with a blue bump cannot be excluded by multi-cloud models, although excluded by Alexander et al. (1999, 2000)using homogeneous models with a filling factor less than unity.Comment: 23 pages, 7 figures. Accepted for Publication in Ap

Exploring adaptation & self-adaptation in autonomic computing systems

This panel paper sets out to discuss what self-adaptation means, and to explore the extent to which current autonomic systems exhibit truly self-adaptive behaviour. Many of the currently cited examples are clearly adaptive, but debate remains as to what extent they are simply following prescribed adaptation rules within preset bounds, and to what extent they have the ability to truly learn new behaviour. Is there a standard test that can be applied to differentiate? Is adaptive behaviour sufficient anyway? Other autonomic computing issues are also discussed

A Store Almost in Sight: The Economic Transformation of Missouri from the Louisiana Purchase to the Civil War

Review of: A Store Almost in Sight: The Economic Transformation of Missouri from the Louisiana Purchase to the Civil War, by Jeff Bremer

Rethinking Place of Business as Choice of Law in Class Action Lawsuits

In the past century, businesses have come to operate on a national and often global level. In the past century, the United States has seen an enormous nationalization and even globalization of business. As a result, the actions of a single company increasingly have the potential to affect people far beyond the boundaries of that company\u27s home state. When one or a few companies injure large numbers of consumers across the country, aggregate litigation (namely the class action lawsuit) becomes an especially attractive remedy. Aggregating claims allows plaintiffs to save time and money and may also enable them to present a more compelling case by showing the extent of damages a defendant allegedly caused. Though some of this litigation arises under federal law, many of the underlying claims are governed by state law. Therefore, before a court can aggregate the claims and allow plaintiffs to proceed as a nationwide class, it must decide which state\u27s law will apply to the claims. This decision frequently creates a classic choice-of-law problem. Rule 23 of the Federal Rules of Civil Procedure authorizes class actions as a form of aggregate litigation. For certification under Rule 23(b)(3), plaintiffs must show that questions of law or fact common to the members of the class predominate over any questions affecting only individual members and that the class action device will provide a superior method of adjudication. Rule 23(b)(3) lists a number of factors that the court should consider in making the certification decision, including the difficulties likely to be encountered in the management of a class action. A court will not likely certify a class action that encompasses too many variations in either law or fact because the class will not meet the predominance requirement or the manageability standard

Rethinking Place of Business as Choice of Law in Class Action Lawsuits

In the past century, businesses have come to operate on a national and often global level. In the past century, the United States has seen an enormous nationalization and even globalization of business. As a result, the actions of a single company increasingly have the potential to affect people far beyond the boundaries of that company\u27s home state. When one or a few companies injure large numbers of consumers across the country, aggregate litigation (namely the class action lawsuit) becomes an especially attractive remedy. Aggregating claims allows plaintiffs to save time and money and may also enable them to present a more compelling case by showing the extent of damages a defendant allegedly caused. Though some of this litigation arises under federal law, many of the underlying claims are governed by state law. Therefore, before a court can aggregate the claims and allow plaintiffs to proceed as a nationwide class, it must decide which state\u27s law will apply to the claims. This decision frequently creates a classic choice-of-law problem. Rule 23 of the Federal Rules of Civil Procedure authorizes class actions as a form of aggregate litigation. For certification under Rule 23(b)(3), plaintiffs must show that questions of law or fact common to the members of the class predominate over any questions affecting only individual members and that the class action device will provide a superior method of adjudication. Rule 23(b)(3) lists a number of factors that the court should consider in making the certification decision, including the difficulties likely to be encountered in the management of a class action. A court will not likely certify a class action that encompasses too many variations in either law or fact because the class will not meet the predominance requirement or the manageability standard

The Ute Indians and the Public School System: A Historical Analysis, 1900-1985

This thesis is a historical case study of the Ute Indians of eastern Utah. The purpose of this thesis is to examine how federal Indian education policy is implemented at the local level. Ute children attend school in the Uintah and Duchesne county school districts. The thesis traces Ute experiences in public schools during crucial transitions in federal policy. From 1900 to 1930, the federal government sought to enroll Indians in public schools in order to teach them white ways. Indian enrollment increased in the 1940s and 1950s when federal funding made the attendance of Ute children lucrative to the school districts. After the reservation boarding school closed in 1952, nearly all of the Ute children attended public schools and faced a school system that was hostile to their culture. A key transition occurred in the 1970s when federal policy shifted to one of self-determination. The Indian Education Act of 1972 made mandatory the direct participation by Indian parents in the implementation of federally funded programs. Many parents failed to grasp the new opportunity. The Ute Tribal Education Division became heavily involved in running Ute history and language classes in the public schools under Title IV of the Indian Education Act of 1972 and under Title VII of the 1965 Elementary and Secondary Education Act. Despite the existence of a policy that advocated self determination, Utes were not really allowed to determine how federal money was spent. The 1972 Indian Education Act established an advisory role for parents rather than an administrative one. Local school districts still controlled the purse strings. Programs run under this act were not integrated into the core curriculum of local schools. Federal Indian education policy changed from decade to decade but local attitudes remained essentially the same, blunting each policy\u27s effectiveness. When the federal government desired assimilation, local residents and Indians fought that goal. When the federal government switched to a policy of self-determination, misunderstanding and outright hostility kept it from fulfillment at the local level. In addition to problems associated with local attitudes, federal legislation also proved unworkable because it gave Indians no real power to make the school districts listen to them

Slit Observations and Empirical Calculations for HII Regions

When analysing HII regions, a possible source of systematic error on empirically derived physical quantities is the limited size of the slit used for the observations. A grid of photoionization models was built through the Aangaba code varying the ionizing radiation spectrum emitted by a stellar cluster, as well as the gas abundance. The calculated line surface brightness was then used to simulate slit observations and to derive empirical parameters using the usual methods described in the literature. Depending on the fraction of the object covered by the slit, the parameters can be different from those obtained from observations of the whole object, an effect that is mainly dependent on the age of the ionizing stellar cluster. The low-ionization forbidden lines are more sensitive to the size of the area covered by the slit than the high-ionization forbidden lines or recombination lines. Regarding the temperature indicator T[OIII], the slit effects are small since this temperature is derived from [OIII] lines. On the other hand, for the abundance indicator R23, which depends also on the [OII] line, the slit effect is slightly higher. Therefore, the systematic error due to slit observations on the O abundance is low, being usually less than 10%, except for HII regions powered by stellar clusters with a relative low number of ionizing photons between 13.6 and 54.4 eV, which create a smaller O++ emitting volume. In this case, the systematic error on the empirical O abundance deduced from slit observations is more than 10% when the covered area is less than 50%.Comment: To be published in MNRAS, accepted in 09/09/2005, 17 pages and 6 figure

The Evolution of Helium and Hydrogen Ionization Corrections as HII Regions Age

Helium and hydrogen recombination lines observed in low-metallicity, extragalactic, HII regions provide the data used to infer the primordial helium mass fraction, Y_P. In deriving abundances from observations, the correction for unseen neutral helium or hydrogen is usually assumed to be absent; i.e., the ionization correction factor is taken to be unity (icf = 1). In a previous paper (VGS), we revisited the question of the icf, confirming a "reverse" ionization correction: icf < 1. In VGS the icf was calculated using more nearly realistic models of inhomogeneous HII regions, suggesting that the published values of Y_P needed to be reduced by an amount of order 0.003. As star clusters age, their stellar spectra evolve and so, too, will their icfs. Here the evolution of the icf is studied, along with that of two, alternate, measures of the "hardness" of the radiation spectrum. The differences between the icf for radiation-bounded and matter-bounded models are also explored, along with the effect on the icf of the He/H ratio (since He and H compete for some of the same ionizing photons). Particular attention is paid to the amount of doubly-ionized helium predicted, leading us to suggest that observations of, or bounds to, He++ may help to discriminate among models of HII regions ionized by starbursts of different ages and spectra. We apply our analysis to the Izotov & Thuan (IT) data set utilizing the radiation softness parameter, the [OIII]/[OI] ratio, and the presence or absence of He++ to find 0.95 < icf < 0.99. This suggests that the IT estimate of the primordial helium abundance should be reduced by Delta-Y = 0.006 +- 0.002, from 0.244 +- 0.002 to 0.238 +- 0.003.Comment: 27 double-spaced pages, 11 figures, 5 equations; revised to match the version accepted for publication in the Ap