bluuebunny/crossref_metadata_2025_split huggingface dataset:
Localization and class groups of module categories with exactness defects
Authors: Holland D. , Wilson S. M. J. 
Published: November 2008

AbstractWe present a new way of forming a grothendieck group with respect to exact sequences. A ‘defect’ is attached to each non-split sequence and the relation that would normally be derived from a collection of exact sequences is only effective if the (signed) sum of the corresponding defects is zero. The theory of the localization exact sequence and, in particular, of the relative group in this sequence is developed. The (‘locally free’) class group of a module category with exactness defect is defined and an idèlic formula for this is given. The role of torsion and of torsion-free modules is investigated. One aim of the work is to enhance the locally trivial, ‘class group’, invariants obtainable for a module while keeping to a minimum the local obstructions to the definition of such invariants.
Symmetry characterizations of certain distributions. 3. Discounted additive functional and large deviations for a general finite-state Markov chain
Authors: Baxter Martin 
Published: November 2008

In Baxter and Williams [1] we began a study of Abel averages,as opposed to the oft-studied Cesàro averages In Baxter and Williams [2], hereinafter referred to as [BW2], we studied the large-deviation behaviour of these averages. In the case where X is an irreducible Markov chain on a finite state-space S = {1,…, n}, we observed thatandwhere π is the invariant distribution of X. We noted thatwhere v is an n-vector, δ(v):= sup{Re(z): z ∈ spect(Q+ V)}, and where spect(·) denotes spectrum (here the set of eigenvalues), Q is the Q-matrix of X, and V denotes the diagonal matrix diag (vi). It is also true that the large-deviation property holds for Ct with rate function I denned on M = {(xt)i ∈ S: xi ≥ 0, Σixi = 1}.
On Markov chains with an enumerable infinity of states
Authors: Foster F. G. 
Published: November 2008

Consider the infinite system of linear ‘inequations’,in which the coefficients pij have the two propertiesWe define as properly divergent (p.d.) a solution, {xi} (i = 0, 1, 2, …), such thatand such that |xi| < ∞ for i < ∞. Since {k + xi} is also a solution for any non-negative constant k, there is no loss in generality in assuming (as we always shall) in place of this last condition thatWe are concerned with conditions for the existence of p.d. solutions.
An example of a divergent perturbation expansion in field theory
Authors: Hurst C. A. 
Published: November 2008

AbstractThe convergence of the perturbation expansion for the S-matrix in interaction representation of a three-boson contact interaction is investigated. A lower bound is obtained for the integrals corresponding to irreducible graphs when the total rest mass of the system is insufficient for bare particles to be created. It is shown that in this case the perturbation expansion cannot converge no matter what value the coupling constant has. A discussion is given of the bearing of this result on the general problem of the convergence of perturbation expansions for the S-matrix in renormalized field theories.
A 3-manifold which is not a product
Authors: Epstein D. B. A. , Scott G. P. 
Published: November 2008

The purpose of this note is to construct a non-compact 3-manifold M with the following properties:(i) M is orientable and irreducible(ii) ∂M is connected and compact and its inclusion in M is a homotopy equivalence(iii) M is not homeomorphic to ∂M × R+.(Throughout this paper, all manifolds will be PL and all embeddings will be PL and locally flat.)
A conjecture of Fejes Tóth on saturated systems of circles
Authors: Dumir Vishwa Chander , Khassa Dharam Singh 
Published: November 2008

A family ℳ of closed circular discs in the plane is called a saturated family or a saturated system of circles if (i) the infimum r of the radii of the discs in ℳ is positive and (ii) every closed disc of radius r in the plane intersects at least one disc in ℳ. For a saturated family ℳ, we denote by S the point-set union of the interiors of the members of ℳ and by S(l) the part of S inside the circular disc of radius l centred at the origin. We define the lower density ρℳ of the saturated family ℳ aswhere V(S(l)) denotes the Lebesgue measure of the set S(l).
Determination of the zeros of a cross-product Bessel function
Authors: Salchev L. Z. , Popov V. B. 
Published: November 2008

In many mechanical and other problems the following equationis reached, where Jν(α) and Yν(α) are Bessel functions of the first and second kind of any real order ν and β is a positive parameter.For example, equation (1) is reached in the case of determining the critical load Pcr, for a simply supported strut with a variable inertia moment by a power law, where the power m is any real number.
The Uniqueness of a Certain Trigonometric Integral
Authors: Offord A. C. 
Published: November 2008

Verblunsky has recently proved the following theorem:Theorem A. Suppose thatfor every positive σ. Writeand suppose that J (σ, x) is bounded in σ, x for σ > 0 and all x. Thenexists almost everywhere, andalmost everywhere.
On the Effective Temperatures of Extended Photospheres
Authors: Chandrasekhar S. 
Published: November 2008

For material stratified in parallel planes in local thermodynamical equilibrium we have Milne's well-known result thatwhere πF is the constant net integrated flux of radiation, τ is the optical depth and B is the “ergiebigkeit” which is related to the temperature T by the relationσ being the Stefan-Boltzmann constant. If we define the effective temperature by the relationwe have from (1)where T1 is the temperature ar τ = 1. In this note we establish a similar result for extended photospheres where the curvature of the outer layers is properly taken into account.
Theoretical Pearls
Authors: Barendsen Erik 
Published: November 2008

AbstractFor numeral systems in untyped λ-calculus the definability of a successor, a predecessor and a test for zero implies the definability of all recursive functions on that system. Towards a disproof of the converse statement, H. P. Barendregt and the author constructed a numeral system consisting of unsolvable λ-terms, being adequate for unary functions. Then, independently, B. Intrigila found an analogous system for all computable functions.
Functional Pearl: On generating unique names
Authors: Augustsson Lennart , Rittri Mikael , Synek Dan 
Published: November 2008

And Joktan begat Almodad, and Sheleph, and Hazarmaveth, and Jerah, and Handoram, and Uzal, and Diklah, and Obal, and Abimael, and Sheba, and Ophir, and Havilah, and Jobab: all these were the sons of Joktan.— Genesis 10:26–29
The ins and outs of Clean I/O
Authors: Achten Peter , Plasmeijer Rinus 
Published: November 2008

AbstractFunctional programming languages have banned assignment because of its undesirable properties. The reward of this rigorous decision is that functional programming languages are side-effect free. There is another side to the coin: because assignment plays a crucial role in Input/Output (I/O), functional languages have a hard time dealing with I/O. Functional programming languages have therefore often been stigmatised as inferior to imperative programming languages because they cannot deal with I/O very well. In this paper, we show that I/O can be incorporated in a functional programming language without loss of any of the generally accepted advantages of functional programming languages. This discussion is supported by an extensive account of the I/O system offered by the lazy, purely functional programming language Clean. Two aspects that are paramount in its I/O system make the approach novel with respect to other approaches. These aspects are the technique of explicit multiple environment passing, and the Event I/O framework to program Graphical User I/O in a highly structured and high-level way. Clean file I/O is as powerful and flexible as it is in common imperative languages (one can read, write, and seek directly in a file). Clean Event I/O provides programmers with a high-level framework to specify complex Graphical User I/O. It has been used to write applications such as a window-based text editor, an object based drawing program, a relational database, and a spreadsheet program. These graphical interactive programs are completely machine independent, but still obey the look-and-feel of the concrete window environment being used. The specifications are completely functional and make extensive use of uniqueness typing, higher-order functions, and algebraic data types. Efficient implementations are present on the Macintosh, Sun (X Windows under Open Look) and PC (OS/2).
Optimal purely functional priority queues
Authors: Brodal Gerth Stølting , Okasaki Chris 
Published: November 2008

AbstractBrodal recently introduced the first implementation of imperative priority queues to supportfindMin, insertandmeldinO(1) worst-case time, anddeleteMininO(logn) worst-case time. These bounds are asymptotically optimal among all comparison-based priority queues. In this paper, we adapt Brodal's data structure to a purely functional setting. In doing so, we both simplify the data structure and clarify its relationship to the binomial queues of Vuillemin, which support all four operations inO(logn) time. Specifically, we derive our implementation from binomial queues in three steps: first, we reduce the running time ofinserttoO(1) by eliminating the possibility of cascading links; second, we reduce the running time offindMintoO(1) by adding a global root to hold the minimum element; and finally, we reduce the running time ofmeldtoO(1) by allowing priority queues to contain other priority queues. Each of these steps is expressed using ML-style functors. The last transformation, known as data-structural bootstrapping, is an interesting application of higher-order functors and recursive structures.
Numerical analysis of dynamical systems
Authors: Stuart Andrew M. 
Published: November 2008

This article reviews the application of various notions from the theory of dynamical systems to the analysis of numerical approximation of initial value problems over long-time intervals. Standard error estimates comparing individual trajectories are of no direct use in this context since the error constant typically grows like the exponential of the time interval under consideration.Instead of comparing trajectories, the effect of discretization on various sets which are invariant under the evolution of the underlying differential equation is studied. Such invariant sets are crucial in determining long-time dynamics. The particular invariant sets which are studied are equilibrium points, together with their unstable manifolds and local phase portraits, periodic solutions, quasi-periodic solutions and strange attractors.Particular attention is paid to the development of a unified theory and to the development of an existence theory for invariant sets of the underlying differential equation which may be used directly to construct an analogous existence theory (and hence a simple approximation theory) for the numerical method.
Computertomographische Befunde bei Milzruptur, subkapsulärem Milzhämatom und perisplenitischem Abszeß
Authors: Böttger E. , Semerak M. , Jaschke W. 
Published: November 2008

ZusammenfassungDie computertomographischen Kriterien der Milzruptur, frischer oder älterer Milzhämatome (Milzpseudozysten) und des perisplenitischen bzw. subphrenischen Abszesses werden anhand von drei eigenen Beobachtungen herausgearbeitet. Es zeigt sich, daß bei den genannten Erkrankungen alle präoperativ relevanten Fragen durch die Computertomographie geklärt werden können, so daß auf die Durchführung der Arteriographie verzichtet werden kann. Eine computertomographische Differentialdiagnose zwischen alten Hämatomen und perisplenitischen Abszessen ist nur unter Einbeziehung anamnestischer und klinischer Daten möglich.
The Use of Intraoperative Image-Guided Surgical Techniques for Reconstruction of Orbital and Zygomatic Deformities
Authors: Frodel John L. , Pacheco Elba 
Published: November 2008

New Concepts in Surgery of the Facial SkeletonSecondary orbital and periorbital skeletal reconstruction remains a difficult challenge. Recent use of intraoperative CT image guided surgery techniques have allowed an improved operator confidence in such reconstructions. In this review, cases illustrating the use of image guided surgery techniques in patients with fixed, secondary orbital and zygomatic deformities will be demonstrated.
Phytoplankton nutrient status and mean water column irradiance in Lakes Malawi and Superior
Authors: Guildford S.J. , Bootsma H.A. , Fee E.J. , Hecky R.E. , Patterson G. 
Published: November 2008

AbstractPhytoplankton growth in Lake Malawi was moderately nitrogen and phosphorus-deficient according to indicators of phytoplankton nutrient status (particulate C:N, C:P, N:P composition ratios, nitrogen and phosphorus debt assays) and occasionally light-deficient during the period of deepest mixing (July and August). Phytoplankton in Lake Superior was light-deficient during most of the year because of the deeply mixed water column. However, during the stratified period when the mean water column irradiance increased, phytoplankton in Lake Superior became severely phosphorus-deficient according to the same nutrient status indicators used in Lake Malawi as well as alkaline phosphatase activity. Specific rates of carbon uptake normalized to particulate carbon, calculated from photosynthesis at optimum light, were on average three times greater in Lake Malawi than in Lake Superior. We calculated that nitrogen and phosphorus inputs from rivers and precipitation supplied &lt; 15% of the demand for these elements due to photosynthesis for both Lake Malawi and Lake Superior and could not explain the observed difference in phytoplankton nutrient status or specific rate of carbon uptake normalized to particulate carbon. The ratio of nitrogen to phosphorus supplied in Lake Malawi is lower and closer to Redfield ratios than that in Lake Superior. We speculate that the more balanced supply ratio of these nutrients, combined with higher rates of internal regeneration in the warmer deeper mixed layer of Lake Malawi, result in phytoplankton that is less nutrient-deficient and has higher specific rates of carbon uptake normalized to particulate carbon than Lake Superior.
Numerical simulation of wind-driven circulation in Lake Tanganyika
Authors: Podsetchine V. , Huttula T. 
Published: November 2008

AbstractA three-dimensional numerical circulation model of Lake Tanganyika, developed within the Lake Tanganyika Research Project (LTR-FAO/FINNIDA) is described. The model is based on full non-linear hydrodynamics equations, modified according to hydrostatic and Boussinesq approximations. A space-splitting scheme is used for numerical approximation of governing equations. Numerical experiments with different wind loading revealed the rather complicated flow structure in Lake Tanganyika.Data for model validation have been collected since May 1993. Main hydrological and meteorological parameters such as water level, wind speed and direction, air temperature, humidity and water temperature are recorded with automatic devices. A simple Lagrangian approach with floating buoys and GPS system is used for current measurements.The obtained surface velocities in different locations lake-wide were compared with the calculated surface currents. Agreement between measured and simulated velocities was satisfactory. Accuracy of the simulations depends on the accuracy of the wind forcing reconstruction. Regular strong winds are observed over Lake Tanganyika during the dry season, a period of trade winds that starts at the end of May and lasts until late August or early September. Numerical experiments with a mesoscale meteorological model (Savijärvi, H., 1995. Sea breeze effects on large–scale atmospheric flow. Contr. Atmos. Phys. 68 335–344) showed that the lake-land breeze system is intensified during this period.The collected data and the numerical experiments with the circulation model provide a solid base for understanding the main hydrophysical processes on a lake-wide scale. Important knowledge has also been obtained on the spatial and temporal dynamics of currents.
Instream flow assessments for regulated rivers in South Africa using the Building Block Methodology
Authors: King J. , Louw D. 
Published: November 2008

Abstract
The demand for water from South Africa’s growing population is creating an ever-increasing pressure on the country’s rivers. The urgent need to provide more water services often conflicts with the desire to maintain or improve the ecological condition of the rivers. To provide guidance on the sustainable use of a river’s water-resources, the Building Block Methodology (BBM) has been developed for assessing the instream flow requirement for any river. Development has been done jointly over the last five years by the national Department of Water Affairs and Forestry (DWAF) and river scientists, and the accent is on identifying a complex of different magnitude flows for maintenance of entire river ecosystems. The BBM caters for the almost universal reality in South Africa of having rapidly to provide scientific guidance on such flows for a river in cases where biological data and understanding of the functioning of the river are limited. However, the methodology works equally well in data-rich situations. The BBM depends on available knowledge and expert opinion, gleaned from experienced river scientists in a structured workshop process. Limited new data of a specific nature are gathered to facilitate the process. Relevant data on the river are prepared in a way that workshop participants can easily understand and quickly begin to use. Scientists typically involved in the workshop, all with specific roles, are those with specialist knowledge of the river or similar rivers in terms of the fish, aquatic invertebrates, riparian vegetation, river importance, habitat integrity, fluvial geomorphology, local hydraulics, water chemistry and social dependence on the riverine ecosystem. Hydrological and hydraulic modelers provide data inputs and facilitate the workshop process by answering questions and producing additional data as requested. The workshop output, reached by consensus, is a quantitative description in space and time of a flow regime that should facilitate maintenance of the river ecosystem in some pre-determined desired future state. Information from a BBM workshop is used by DWAF in the Planning phase of a proposed water-resource development. Further development of the BBM, to extend it into the Design, Construction and Operation phases, has been initiated. This includes linking with a public participation process, input into design of the scheme, base-line studies of the river and subsequent monitoring to assess the efficacy of the recommended flow regime.
Overview and characterization of the hydrology and primary producer communities of selected coastal lagoons of Yucatán, México
Authors: Herrera-Silveira Jorge A. , R. Javier Ramírez , J. Arturo Zaldivar 
Published: November 2008

Abstract
The major hydrological characteristics of the coastal lagoons of Yucatán and their relationship with the space-time pattern of the primary producer communities are described. The weather patterns in the region play an important role in the seasonal changes of nutrient inputs, which are related to the groundwater discharges. The fluctuations of the mean sea level in response to freshwater discharges and frontal systems influenced the differences observed in the residence time of water, which could play an important role in the accumulation of toxic substances from sewage discharges and biological metabolism. The spatial distribution of primary producers was heterogeneous with high biomass production in the middle zone of the lagoons. The dominant group in each system changed seasonally in response to the coupling between external forces and their life cycles; however, the submerged macrophytes might be the principal group in these shallow aquatic ecosystems. The mangrove vegetation experienced strong differences in their structural development which could be used as a signal of the impacts observed in the area. Though there is no river in the region, the mangrove vegetation was well represented in the North Coast and irregular freshwater inputs favored the dispersion of this community. However, because the seasonality of these freshwater inputs did not show a better structure, their contribution to total primary production should be limited in some areas to a specific period of the year. The heterogeneity observed in the hydrology and primary producer communities suggested a high diversity and the existence of different food webs that offer various potential uses. However, for adequate management polices, these uses must be planned considering the space-time pattern of the hydrology and primary producers.
Epipelic diatoms from the Matanza-Riachuelo river (Argentina), a highly polluted basin from the pampean plain: biotic indices and multivariate analysis
Authors: Gómez N. 
Published: November 2008

AbstractDuring the fall and winter of 1995, ninety-two samples were collected from twenty-three sampling stations in the Matanza-Riachuelo river basin. Epipelic diatoms and physico-chemical parameters were studied to establish water quality. Ecological methodologies (species richness, diversity and saprobity indices and multivariate analysis) were employed to assess the impact of the pollution on diatom assemblages. Suspended solids, biological and chemical oxygen demands increased downstream, and dissolved oxygen, pH and transparency increased upstream. Conductivity was variable. This fluvial system is affected by organic and inorganic pollutants, many of them toxic. The presence of heavy metals, phenols, pesticides, hydrocarbons among other chemicals, mostly account for the impoverishment of the diatom assemblages of the basin, thus leading to changes in assemblages structure. Changes in water quality were better reflected by species richness, diversity indices and by principal component analysis than pollution indices in this basin.
Exemptionalism vs environmentalism: the crucial debate on the value of ecosystem health
Authors: Cairns J. 
Published: November 2008

AbstractThe concept of exemptionalism holds that human society is exempt from the biophysical laws that control other species because of human ingenuity, technology, creativity and economic systems. Some economists believe that resource depletion is irrelevant because alternative resources will be developed if there is enough demand backed by money. A related statement is that any problem created by technology can be resolved by technology. Within these frames of reference, ecosystem health is of minor, arguably no, importance to the exemptionalist.The concept of environmentalism views Homo sapiens as just another biological species that is tightly controlled by biophysical laws, but which is able to modify the biophysical laws more than other species. This view acknowledges human society's dependence on ecological life support systems and the services they provide and assumes that the well-being of human society is closely linked with the health of natural systems. Only within the later framework will ecosystem health be a major concern of human society.