bluuebunny/crossref_metadata_2025_split huggingface dataset:
Geometric characterization of linearisable second-order differential equations
Authors: Martínez Eduardo , Cariñena José F. 
Published: November 2008

AbstractGiven an Ehresmann connection on the tangent bundle τ: TM → M we define a linear connection on the pull-back bundle τ*(TM). With the aid of this tool, necessary and sufficient conditions are derived for the existence of local coordinates in which a system of second-order differential equations is linear.
Superoptimal approximation by meromorphic functions
Authors: Peller V. V. , Young N. J. 
Published: November 2008

AbstractLet G be a matrix function of type m × n and suppose that G is expressible as the sum of an H∞ function and a continuous function on the unit circle. Suppose also that the (k – 1)th singular value of the Hankel operator with symbol G is greater than the kth singular value. Then there is a unique superoptimal approximant to G in : that is, there is a unique matrix function Q having at most k poles in the open unit disc which minimizes s∞(G – Q) or, in other words, which minimizes the sequencewith respect to the lexicographic ordering, whereand Sj(·) denotes the jth singular value of a matrix. This result is due to the present authors [PY1] in the case k = 0 (when the hypothesis on the Hankel singular values is vacuous) and to S. Treil[T2] in general. In this paper we give a proof of uniqueness by a diagonalization argument, a high level algorithm for the computation of the superoptimal approximant and a recursive parametrization of the set of all optimal solutions of a matrix Nehari—Takagi problem.
A remark on the containment of c0 in spaces of compact operators
Authors: Emmanuele G. 
Published: November 2008

Let X, Y be two Banach spaces. By L(X, Y) (resp. K(X, Y)) we denote the Banach space of all bounded, linear (resp. compact, bounded, linear) operators from X into Y. Several papers have been devoted to the question of when c0 embeds isomorphically into K(X, Y) (see 5, 8, 9 and their references) and its relationship with the following question:(i) is K(X, Y) always uncomplemented in L(X, Y) when L(X, Y)K(X, Y)?
New classes of Banach spaces which are M-ideals in their biduals
Authors: Werner Dirk 
Published: November 2008

A subspace X of a Banach space Y is called an M-ideal if there is an L-projection P on Y* whose kernel is X1, the annihilator of X; that is, we haveIn the case that Y is the bidual of X, a natural linear projection on X*** = Y* with kernel X1 is available, namely .
Nonlinear integral inequalities of the Volterra type
Authors: Szwarc Ryszard 
Published: November 2008

We are studying the integral inequalitywhere all functions appearing are defined and increasing on the right half-axis and take the value zero at zero. We are interested in determining when the inequality admits solutions u(x) which are non-vanishing in a neighbourhood of zero. It is well-known that if ψ(x) is the identity function then no such solution exists. This due to the fact that the operator defined by the integral on the right-hand side of the equation is linear and compact. So if we are interested in non-trivial solutions it is natural to require that ψ(x) > 0 at least for all non-zero points in some neighbourhood of zero. One of the typical examples is the power function ψ(x) = xα, where α < 1. This situation was explored in [2]. The functions a(x) that admit non-zero solutions were characterized by Bushell in [1]. For a general approach to the problem we refer to [2], [3] and [4].
Specific Heats of Solids due to Molecular Rotations
Authors: Chang T. S. 
Published: November 2008

Bethe's method, used in the problem of order-disorder transitions in alloys, is applied formally to the problem of molecular rotations in solids. To apply this method, we assume that the solid is entirely homogeneous, and that the state of rotation is the same throughout the solid. Without this assumption, the application of this method is impossible.A particular form of the mutual potential energy between two neighbouring molecules has been chosen, and classical statistics is employed throughout. The calculations are made entirely after the manner of Bethe, and the similarities of the two problems are pointed out. The result is that there is a critical temperature, and also a discontinuity in the specific heat of the magnitude of some ten times the Boltzmann constant per molecule, arising from the sudden setting in of the rotations as the temperature is increased beyond the critical point. Agreement with the experiments is bad, indicating that a more profound theory is necessary.
Extended natural semantics
Authors: Hannan John 
Published: November 2008

AbstractWe extend the definition of natural semantics to include simply typed λ-terms, instead of first-order terms, for representing programs, and to include inference rules for the introduction and discharge of hypotheses and eigenvariables. This extension, which we call extended natural semantics, affords a higher-level notion of abstract syntax for representing programs and suitable mechanisms for manipulating this syntax. We present several examples of semantic specifications for a simple functional programming language and demonstrate how we achieve simple and elegant manipulations of bound variables in functional programs. All the examples have been implemented and tested in λProlog, a higher-order logic programming language that supports all of the features of extended natural semantics.
Empirical and analytic study of stack versus heap cost for languages with closures
Authors: Appel Andrew W. , Shao Zhong 
Published: November 2008

AbstractWe present a comprehensive analysis of all the components of creation, access and disposal of heap-allocated and stack-allocated activation records. Among our results are:•Although stack frames are known to have a better cache read-miss rate than heap frames, our simple analytical model (backed up by simulation results) shows that the difference is too trivial to matter.•The cache write-miss rate of heap frames is very high; we show that a variety of miss-handling strategies (exemplified by specific modern machines) can give good performance, but not all can.•Stacks restrict the flexibility of closure representations (for higher-order functions) in important (and costly) ways.•The extra load placed on the garbage collector by heap-allocated frames is small.•The demands of modern programming languages make stacks complicated to implement efficiently and correctly.Overall, the execution cost of stack-allocated and heap-allocated frames is similar; but heap frames are simpler to implement and allow very efficient first-class continuations.
Proving the correctness of compiler optimisations based on a global analysis: a study of strictness analysis†
Authors: Burn Geoffrey , Le Métayer Daniel 
Published: November 2008

AbstractA substantial amount of work has been devoted to the proof of correctness of various program analyses but much less attention has been paid to the correctness of compiler optimisations based on these analyses. In this paper we tackle the problem in the context of strictness analysis for lazy functional languages. We show that compiler optimisations based on strictness analysis can be expressed formally in the functional framework using continuations. This formal presentation has two benefits: it allows us to give a rigorous correctness proof of the optimised compiler; and it exposes the various optimisations made possible by a strictness analysis.
THE HYDRA OF HOROWITZIAN HISTORY
Authors: Dottin Paul Anthony 
Published: November 2008

AbstractWhether to provide reparations to African Americans for the atrocities of slavery and segregation is arguably the most controversial public matter concerning race in the United States today. This debate, a clash over the economics and ethics of equality, is nothing less than a struggle over the future of racial identity, race relations, and racial progress in the current post–civil rights movement era.With the stakes for African Americans so high, and the prospects for affirmative action dim, public intellectuals have weighed in heavily on each side of the issue. Randall Robinson—author of the best-known work advocating for reparations,The Debt: What America Owes to Blacks(2000)—and David Horowitz—the reparationist movement's most reviled nemesis and author ofUncivil Wars: The Controversy over Reparations for Slavery(2002)—have become the alpha and omega of almost any deliberation on Black reparations.Not surprisingly, rancorous rhetoric has often overshadowed rigorous research on the veracity of antireparations and proreparations claims. This essay aims to correct this problem with an extensive analysis of David Horowitz's (2002) arguments, providing a synthesis of data, concepts, theories, and methodologies from the disciplines of sociology, history, economics, and anthropology. This essay finds that Horowitz's use of academic scholarship to discredit African American reparations fails to meet the “scientific” standards he demands of his opponents.
Zur Differentialdiagnose der echoarmen Schilddrüse
Authors: Mosser H. , Hruby W. , Braun U. , Stellamor K. , Habsburg E. 
Published: November 2008

Die Hypothyreose als funktioneller Endzustand einer abgelaufenen Thyreoiditis stellt aufgrund der uncharakteristischen und oft schleichend verlaufenden Klinik ein diagnostisches Problem dar (8, 11, 13). In der reichlich vorhandenen Schilddrüsenliteratur gibt es kaum systematische Berichte über die sonographische Organstruktur bei diesem Krankheitsbild.In einer prospektiven Studie fanden wir für diese Entität eine charakteristische Sonomorphologie des Organs hinsichtlich Struktur, Größe und Kontur.
Postcolonial Criticism, Transnational Identifications and the Hegemonies of Dancehall's Academic and Popular Performativities
Authors: Noble Denise 
Published: November 2008

Despite the unprecedented freedoms that decolonization has brought for many Black1 people – especially in specific regions of the African Diaspora – freedom and its fulfilment, adequate signs and contested meanings remain a preoccupation within Black cultural discourses and practices. At the same time, while political and cultural nationalisms have led to greater political and civil rights, racism has not been eradicated. Furthermore, the new postcolonial globalizations of capital, people and cultures have destabilized the collective identities that framed twentieth-century struggles for national sovereignty and equal citizenship, without necessarily erasing them. Instead, they remain, no longer securely anchored in their old homogenous appearances, but re-configured through the inner differences and contradictions of gender, sexuality, ethnicity and religion. This article addresses these internal differences and the ways in which they produce new contestations over race, the meaning of Black representation and postcolonial freedom, negotiations that are increasingly traced on the intimate contours of the body and the self, through practices of personal consumption, erotic hedonism and style as key performances of freedom. It achieves this through examining two localized moments in the transnational and diasporic circulation of Jamaican dancehall culture, understood as a privileged public space for the performance of Black identifications and personal freedom. It argues that the eroticized discourses of ethnicity, race and gender found in dancehall culture articulate the dominance of neo-liberal conceptions of freedom at the same time as they express, resist and comment on new cultural hegemonies not reducible to racism or the power of the West; that is how dancehall expresses the new problematizations of postcoloniality. 1 Except when quoting other writers, I will capitalise the word Black, in order to recognise Black identity as a historically and politically constituted experience and representational category, and not solely denoting skin colour.
Exotic species in large lakes of the world
Authors: Hall S.R. , Mills E.L. 
Published: November 2008

AbstractMany of the large lakes of the world have been exposed to the introduction of exotic species. We have reviewed here the introduction of aquatic species in 18 large lakes on five continents (Laurentian Great Lakes, African Great Lakes, several Canadian lakes, Lake Titicaca, Lake Baikal, Lake Ladoga, Gatun Lake, and Lake Biwa). We found that human activities, social preferences, and policy decisions are often associated with the spread of species in these large lakes. However, the spread and resulting ecological effects of introduced species varied among the case studies reviewed (ranging from the failure of brown trout introduction in Lake Titicaca to successful introduction of Nile Perch in Lake Victoria). Those species that did establish successful populations often had major impacts upon the ecosystems of these lakes via a variety of processes, including predation, disturbance, habitat modification and competition. Although introduction of predators often negatively impacted native species (e.g. Nile perch in Lake Victoria, peacock bass in Lake Gatun), species introduced to lower trophic levels (e.g. sardine in Lakes Kariba and Kivu, rainbow smelt in Canadian Lakes) affected fisheries and altered food web structure as well. Exotic species in large lakes of the world were not limited to fish species: plants (e.g. in Lakes Baikal and Biwa), invertebrates (e.g. in Lake Ladoga), and parasites and pathogens (e.g. in Lake Titicaca) have been introduced, but it was often difficult to discern the food web and ecosystem effects of these organisms. Exotic species also impacted socio-economic systems, having both positive (e.g. Lakes Victoria, Titicaca, Kivu, and Kariba, and the Laurentian Great Lakes) and negative (e.g. Lakes Victoria and Titicaca, and the Laurentian Great Lakes) repercussions for humans who depended upon these lakes for food and income. Unfortunately, our understanding of the impacts and extent of introductions on large lake ecosystems often remains speculative at best. The introduction and spread of exotic species will continue to threaten large lakes of the world into the twenty-first century. Exotic species introductions are a global problem that deserves global attention and understanding.
Effect of ultraviolet radiation on the bioavailability of marine diatom-derived low-molecular-weight dissolved organic matter
Authors: Naganuma T. , Fukai I. , Murakami Y. , Nakane T. , Sukizaki S. 
Published: November 2008

Abstract
The effect of ultraviolet irradiation on diatom-derived dissolved organic matter used as a bacterial growth substrate was investigated. The dissolved organic matter fraction of 100–1000 daltons (low molecular weight) was prepared from a culture of a marine diatom, Chaetoceros sp. This dissolved matter was then exposed to ultraviolet-A and -B irradiation at naturally occurring intensities of 0–44 kJ m-2. The concentration of low-molecular-weight dissolved organic matter decreased as ultraviolet irradiation increased, which was a reflection of photolytic mineralization of the material.
The irradiated organic matter was added to the culture of a Vibrio strain to assess its bioavailability. Bacterial growth was enhanced with the irradiated material, which was probably due to the photolytic production of more bioavailable monomeric substrates. The loss of the low-molecular-weight dissolved organic material concentration was counterbalanced by enhanced bioavailability. Thus, ultraviolet irradiation of the natural diatom-derived low-molecular-weight dissolved organic matter pool may be net-positive for the growth of marine bacteria.
Methods for assessing the toxicological significance of metals in aquatic ecosystems: bio-accumulation–toxicity relationships, water concentrations and sediment spiking approaches
Authors: Borgmann U. 
Published: November 2008

Abstract
Although the published literature abounds with studies showing contamination of aquatic environments by metals, there are very few data which actually demonstrate the biological impact of this contamination. Biological impacts such as alteration of in situ communities and demonstration of toxicity in environmental samples often occur at sites with elevated metal concentrations, but this does not prove that metals are actually responsible for these effects. Correlation is not proof of cause and effect. Metal-induced biological effects cannot usually be inferred from measured environmental concentrations because metal bio-availability can vary dramatically from site to site. Differences in metal bio-availability lead to differences in metal bio-accumulation, which in turn lead to differences in metal-induced effects. On the other hand, metal concentrations in biota are often much better indicators of potential biological impact than concentrations in the environment, because differences in metal bio-availability are automatically taken into account. Measurement of the body concentration of metals is a powerful tool for predicting metal effects, especially for non-essential and non-regulated metals. The body burden approach is more limited when applied to essential metals such as copper and zinc. Alternate methods which provide useful information on metal bio-availability, especially for copper and zinc, include measurement of metals in the overlying water during sediment toxicity tests, and sediment spiking with additional metal.
Modification of an index of biotic integrity and development of reference condition expectations or dunal, palustrine wetland fish communities along the southern shore of Lake Michigan
Authors: Simon T.P. 
Published: November 2008

Abstract
I modified and calibrated an index of biotic integrity (IBI) to assess wetland quality of dunal, palustrine wetlands along the southern shore of Lake Michigan. Fish communities were sampled using a combination of electrofishing and seining techniques to collect a representative sample. A combination of 50 historical and recent sites were sampled from northeast Illinois and northwest Indiana to develop reference expectations for dunal wetlands less than 35 ha surface area. I examined 36 attributes of wetland fish communities to derive a dunal, palustrine IBI. Several metrics from the original IBI were retained including: total number of species, number of sensitive species, and percent tolerant species. Trophic composition characters included the percentage of omnivores and insectivores. Fish condition was evaluated using the catch-per-unit of effort and the percentage of deformities, eroded fins, lesions, and tumours (DELT). Several metrics were modified from the original IBI to better reflect water resource quality in dunal wetlands. The number of darter species was replaced by a combination of the ecologically similar number of darter and madtom species; number of sunfish species was modified to the number of centrarchid species, which included the black bass species; number of sucker species was replaced by the number of minnow species since few sucker species were anticipated in dunal wetlands; and I substituted percent carnivores with percent pioneer species. Pioneer species reflect wetland stability and water permanence. Hybrids were not important constituents of wetland communities and did not show a relationship with wetland degradation, so I substituted the percentage of lake-obligate species to reflect species that were dominant in lentic waters.
Realistic assessments of ecotoxicity using traditional and novel approaches
Authors: Burton G.A. 
Published: November 2008

Abstract
The science of ecotoxicology has made exciting advances during the past few years. Recent advances in the use of sensitive subcellular biomarkers, bioaccumulation and food web models, ultra-trace level detection of contaminants, and contaminant partitioning and bioavailability factors have allowed ecotoxicologists to better define contaminant exposures. These advances, when integrated with more traditional approaches (e.g. standardized laboratory toxicity testing, population/community structure characterization) can provide meaningful assessments of ecosystem perturbations. Despite these advances, there is still a limited understanding or application of the complex fate and effect interactions of multiple stressors and receptors in assessments of ecosystem contamination. This reality raises uncertainties which cannot be ignored when using traditional, short-term approaches of assessment. The integrated use of newer in situ assessments of multi-stressor exposures, coupled with more traditional laboratory and field methods reduces uncertainty and improves our ability to identify significant stressors.
Ecotoxicological aspects of chlorinated fatty acids
Authors: Ewald G. 
Published: November 2008

Abstract
Chlorinated fatty acids have been shown to be the major constituent of compounds contributing to the extractable organically bound chlorine found in fish and other environmental samples. Chlorinated fatty acids may occur naturally, however high concentrations in biota are connected to anthropogenic inputs either directly as in the case of pulp bleaching, or indirectly as they may be formed by metabolism of other chlorinated organic compounds. The ecotoxicological properties of chlorinated fatty acids are different from ‘traditional’ environmental pollutants such as polychlorinated biphenyls and DDT. Normally, three criteria need to be met for a compound to qualify as a persistent organic pollutant: lipophilicity, persistence and toxicity. The chlorinated fatty acids are not persistent in the traditional sense that they resist strong oxidising agents. Still they can be considered ‘biologically stable’ as they may persist within an organism incorporated into depot- and membrane lipids. Chlorinated fatty acids are accumulated by biota with high efficiency from food and they are therefore most probably being transferred in the food web. This transfer from prey to predator may be comprised in the suggested term, biological stability. These compounds have been shown to exhibit adverse effects in several toxicity tests using a variety of species as well as in mammalian cell cultures. For example, sperm motility has been impaired at concentrations as low as 0.057 mg l−1. Despite their toxicity, chlorinated fatty acids do not induce enzyme systems such as P450 and EROD in fish, nor do they seem to induce other elimination efforts. Thus, they are apparently accumulated and otherwise treated as normal fatty acids. This lack of organism recognition of chlorinated fatty acids as xenobiotic compounds gives a new perspective on the risk assessment of these compounds, concerning both the modelling of their ecosystem fate and the design of test-systems for detection of their ecosystem effects.