bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quantifier elimination and parametric polymorphism in programming languages
Authors: Mairson Harry G. 
Published: November 2008

AbstractWe present a simple and easy-to-understand explanation of ML type inference and parametric polymorphism within the framework of type monomorphism, as in the first order typed lambda calculus. We prove the equivalence of this system with the standard interpretation using type polymorphism, and extend the equivalence to include polymorphic fixpoints. The monomorphic interpretation gives a purely combinatorial understanding of the type inference problem, and is a classic instance of quantifier elimination, as well as an example of Gentzen-style cut elimination in the framework of the Curry-Howard propositions-as-types analogy.
Polymorphic type, region and effect inference
Authors: Talpin Jean-Pierre , Jouvelot Pierre 
Published: November 2008

AbstractWe present a new static system which reconstructs the types, regions and effects of expressions in an implicitly typed functional language that supports imperative operations on reference values. Just as types structurally abstract collections of concrete values, regions represent sets of possibly aliased reference values and effects represent approximations of the imperative behaviour on regions.We introduce a static semantics for inferring types, regions and effects, and prove that it is consistent with respect to the dynamic semantics of the language. We present a reconstruction algorithm that computes the types and effects of expressions, and assigns regions to reference values. We prove the correctness of the reconstruction algorithm with respect to the static semantics. Finally, we discuss potential applications of our system to automatic stack allocation and parallel code generation.
Algorithmic debugging for lazy functional languages
Authors: Nilsson Henrik , Fritzson Peter 
Published: November 2008

AbstractLazy functional languages have non-strict semantics and are purely declarative, i.e. they support the notion of referential transparency and are devoid of side-effects. Traditional debugging techniques are, however, not suited for lazy functional languages, since computations generally do not take place in the order one might expect. Sincealgorithmic debuggingallows the user to concentrate on the declarative aspects of program semantics, and will semi-automatically find functions containing bugs, we propose to use this technique for debugging lazy functional programs. Because of the non-strict semantics of lazy functional languages, arguments to functions are in general partially evaluated expressions. The user is, however, usually more concerned with the values that these expressions represent. We address this problem by providing the user with astrictifiedview of the execution trace whenever possible. In this paper, we present an algorithmic debugger for a lazy functional language based on strictification and some experience in using it. A number of problems with the current implementation of the debugger (e.g. too large trace size and too many questions asked) are also discussed and some techniques for overcoming these problems, at least partially, are suggested. The key techniques areimmediate strictificationandpiecemeal tracing.
Type classes with existential types
Authors: Läufer Konstantin 
Published: November 2008

AbstractWe argue that the novel combination of type classes and existential types in a single language yields significant expressive power. We explore this combination in the context of higher-order functional languages with static typing, parametric polymorphism, algebraic data types and Hindley–Milner type inference. Adding existential types to an existing functional language that already features type classes requires only a minor syntactic extension. We first demonstrate how to provide existential quantification over type classes by extending the syntax of algebraic data type definitions, and give examples of possible uses. We then develop a type system and a type inference algorithm for the resulting language. Finally, we present a formal semantics by translation to an implicitly-typed second-order λ-calculus and show that the type system is semantically sound. Our extension has been implemented in the Chalmers Haskell B. system, and all examples from this paper have been developed using this system.
Functional Pearls
Authors: Gibbons Jeremy 
Published: November 2008

AbstractThe Third Homomorphism Theorem is a folk theorem of the constructive algorithmics community. It states that a function on lists that can be computed both from left to right and from right to left is necessarily a list homomorphism – it can be computed according to any parenthesization of the list. We formalize and prove the theorem, and use it to improve an O(n2) sorting algorithm to O(n log n).
Linear stability analysis in the numerical solution of initial value problems
Authors: van Dorsselaer J.L.M. , Kraaijevanger J.F.B.M. , Spijker M.N. 
Published: November 2008

This article addresses the general problem of establishing upper bounds for the norms of the nth powers of square matrices. The focus is on upper bounds that grow only moderately (or stay constant) where n, or the order of the matrices, increases. The so-called resolvant condition, occuring in the famous Kreiss matrix theorem, is a classical tool for deriving such bounds.Recently the classical upper bounds known to be valid under Kreiss's resolvant condition have been improved. Moreover, generalizations of this resolvant condition have been considered so as to widen the range of applications. The main purpose of this article is to review and extend some of these new developments.The upper bounds for the powers of matrices discussed in this article are intimately connected with the stability analysis of numerical processes for solving initial(-boundary) value problems in ordinary and partial linear differential equations. The article highlights this connection.The article concludes with numerical illustrations in the solution of a simple initial-boundary value problem for a partial differential equation.
Stability of Comorbid Psychiatric Diagnosis among Youths in Treatment and Aftercare for Alcohol Use Disorders
Authors: Hawke Josephine M. , Kaminer Yifrah , Burke Rebecca , Burleson Joseph A. 
Published: November 2008

Objectives To examine the stability of comorbid psychiatric diagnoses among a sample of 50 adolescents in cognitive-behaviorally-based treatment for alcohol and other substance use disorders (AOSUD). Methods A standardized psychiatric interview was administered at baseline and 12 month later to obtain current comorbid psychiatric disorders. Chi square and Wilconxon sign tests coefficients were used to examine changes in threshold status by type of disorder. Pearson's coefficients were used to identify correlates with improvements in threshold status, include the need for alcohol treatment and alcohol consumption at follow-up. Results Diagnostic status changes considerably over time. Prevalence rates for comorbid disorders overall declined. Only declines in mood and externalizing disorders achieved statistical significance. Improvements were positively correlated with mental health service utilization and negatively correlated with the need for alcohol treatment and consumption at 12 months. Conclusions Further investigation on the stability and change in diagnostic status of AOSUD youths is warranted.
What Do Adolescents Exposed to Alcoholic Anonymous Think about 12-Step Groups?
Authors: Kelly John F. , Myers Mark G. , Rodolico John 
Published: November 2008

Objectives Referral to Alcoholics Anonymous (AA) and Narcotics Anonymous (NA) is a common continuing care recommendation. Evidence suggests some youth benefit, yet, despite referrals, youth participation is low. Little is known about adolescents’ experiences of AA/NA. Greater knowledge would inform and help tailor aftercare recommendations. Method Two clinical samples of youth (N = 74 and N = 377) were asked about their perceptions of, and experiences with, AA/NA with responses categorized by content into domains assessed for face validity and reliability. Results The aspects of AA/NA youth liked best were general group dynamic processes related to universality, support, and instillation of hope. The most common reason for discontinuing was boredom/lack of fit. Conclusions General group-therapeutic, and not 12-step-specific, factors are most valued by youth during early stages of recovery and/or degree of AA/NA exposure. Many youth discontinue due to a perceived lack of fit, suggesting a mismatch between some youth and aspects of AA/NA.
The regulation of phytoplankton population dynamics in the world’s largest lakes
Authors: Reynolds C.S. , Reynolds S.N. , Munawar I.F. , Munawar M. 
Published: November 2008

Abstract
The world’s largest lakes, really inland seas, are characterised by long retention times, and are dominated by internal physical forcing, generally low nutrient loadings and predominantly internal recycling. Most are oligotrophic. Many are severely phosphorus deficient. Certainly few ever support large crops of phytoplankton. Horizontal heterogeneity sometimes permits enhanced production in shallow bays or behind thermal bars and occasional blooms develop under conditions of near-surface stratification.
An assessment of published information on the composition and seasonality of phytoplankton in the open water habitats of these lakes confirms the oligotrophic nature of the world’s great lakes. There is a predominance of diatoms at all latitudes; chrysophytes are seasonally prominent in some lakes at high latitude; other flagellates, including dinoflagellates, and species of cyanobacteria represent increasing proportions of the pelagic biomass towards the equator. There is an indication that species composition is influenced by underwater light availability and a positive correlation between Microcystis plankton and relatively higher concentrations of total phosphorus (TP &gt; 30 μg l-1) is suggested. Picoplankton is apparently abundant during periods of relatively high insolation of the water column. Although the carrying capacity of the nutrients available is scarcely large, the production of biomass is strongly related to seasonal variability in the intensity and extent of water-column mixing and its relation to the periodicity and underwater penetration of photosynthetically active radiation. Attainment of nutrientlimited crops generally coincides with shallow mixing whereas deep circulation suppresses production.
The differential effects of latitude, local climate and salinity upon this general deduction are also evaluated. The role of grazing, its contribution to nutrient recycling, and its contribution to sustaining pelagic food webs, is also considered. The paper makes some deductions about the threats placed on large-lake ecosystems by pollution, eutrophication and acidification and upon how their ecosystem health might be monitored and conserved in the future.
Mutagenicity of bleached and unbleached effluents from Baikalsk pulp and paper mill at Lake Baikal, Russia
Authors: Kotelevtsev S.V. , Hänninen O.O.P. , Lindström-Seppä P.A. , Huuskonen S.E. , Stepanova L.I. , Glaser V.M. , Beim A.M. 
Published: November 2008

AbstractThe mutagenicity of bleached pulp mill effluents was compared to the mutagenicity of unbleached waste waters. Mutagenicity was assessed with the Ames test, using metabolic activation systems isolated from the liver of rats and fish. Liver extracts from fish caught in polluted areas, and from fish experimentally exposed to waste water, were also investigated. Pulp mill effluents taken after chlorination showed mutagenic activity. The activity diminished during the waste water treatment. Tissue extracts from fish exposed to various concentrations of treated bleached and unbleached pulp mill effluents showed only slight mutagenic activity in a few samples. In the case of bleached pulp mill effluents monooxygenase activities were elevated in those samples where slight mutagenicity was observed. In the case of unbleached effluents no such correlation was found.
Sediment and water phase toxicity and UV-activation of six chemicals used in military explosives
Authors: Dave G. , Nilsson E. , Wernersson A.-S. 
Published: November 2008

Abstract
Explosives used in ammunition have been dumped in both lakes and oceans before the potential environmental effects of these chemicals were understood. Growing environmental concern in society and in the Swedish military resulted in a project dealing with the aquatic toxicology of explosives. The aim of the present study was to assess the hazard of six explosives by determining the acute sediment and water phase toxicity for two crustaceans (Daphnia magna and Nitocra spinipes). Detoxification during storage was used as an indication of degradability (hydrolysis and biodegradation). The effect of ultraviolet light on the toxicity of these compounds was determined by post-exposure to ultraviolet light and determination of toxicity enhancement. The explosives were picric acid, trinitrotoluene, (2,4-dinitrotoluene), hexahydro-1,3,5-trinitro-1,3,5-trazine, nitroguanidine, and pentyl. The stabilising agent diphenylamine was tested in the same way. For the major explosive, trinitrotoluene, the water-phase EC/LC50s were between 5 and 20 mg l−1 and the toxicity was not significantly affected by storage of test solutions for 30 days, indicating hydrolytic stability. The toxicity was not affected by addition of sediment, indicating that trinitrotoluene was not bound appreciably to sediment, but toxicity decreased after storage for 30 days in the presence of sediment, indicating biological degradation or slow adsorption of the chemical. The toxicity of the other explosives was similar or lower than for trinitrotoluene, but the stabilising agent diphenylamine was slightly more toxic with EC/LC50s between 0.5 and 5 mg l−1. Photoinduced toxicity by ultraviolet light is known for many chemicals including polycyclic aromatic hydrocarbons and trinitrotoluene. The latter was confirmed in this study and especially for degraded trinitrotoluene. 2,4-Dinitrotoluene, which is one degradation product of trinitrotoluene was also activated by ultraviolet light. The toxicity of diphenylamine decreased after storage in water (hydrolysis) and with sediment (biodegradation), but both diphenylamine and its degradation products exhibited photoinduced toxicity.
Interactions of cesium with sediments from Mexican aquatic environments
Authors: Hansen Anne M. , Cerezo-Román Apolinar , Ortega-Lara Vicente 
Published: November 2008

AbstractThrough batch experiments, mathematical and numerical modeling, the migration behavior of radioactive cesium (Cs) was evaluated in water-sediment phases from different Mexican continental aquatic systems and near-coastal marine environments. The objective of the experiment was to understand and simulate the transport, accumulation, and remobilization patterns occurring in these systems as a result of natural and man-made variations in solution chemistry and solid phase compositions of the sediments. The effects of soluble ligands on the incorporation of Cs in sediments from the different study environments were also evaluated. The experimental design reflected variations of system parameters, such as the type of sediment, ionic strength, pH, time of contact, and concentrations of different dissolved ions that either competed with Cs for the same adsorption sites or formed solution species with the study metal. Time-dependent and equilibrium constants were obtained for the incorporation of Cs in sediment samples from the different study environments. Cs adsorbed as outer sphere complexes and exchanged with other cations in the clay minerals. Major ion concentrations in solution affected the distribution of the study metal between the dissolved forms and those attached to the solid surfaces of the sediments. Cs desorption was evaluated by varying the pH and adding different concentrations of EDTA, CO2, or pentavanadate to the experimental systems. Experimental results were used to calibrate time-dependent and equilibrium models which in turn were used to describe and quantify the observed phenomena. The results obtained may help in describing the transport and distribution of radioactive Cs in natural aquatic environments and in the rehabilitation of sites that were contaminated by planned or accidental releases from the atomic energy industry.
Acetylcholinesterase activity of the freshwater cladoceran, Moina macrocopa, used as an in vitro screening tool for water quality
Authors: Martinez-Tabche L. , Mora B. Ramirez , German-Faz C. , Diaz-Pardo E. 
Published: November 2008

Abstract
A rapid, inexpensive enzymatic method is proposed for screening water quality in the laboratory, on board ship or on-site. The method uses the enzyme acetylcholinesterase extracted with Triton X-100 from the supernatant of a homogenate of the cladoceran, Moina macrocapa. Modification of the specific activity of the enzyme compared to controls is measured during incubation of the enzyme extract with water from various sources. This study demonstrated differential response to enzyme activity in water from a large reservoir (Ignacio Ramírez) compared with effluent from an oil refinery (18 de Marzo). In vitro AChE activity is suggested as a rapid test to identify water samples that are toxic or of poor quality and that should be subject to further chemical analysis and toxicity testing.
An outline of a diagnostic system of criteria to rank chemical threats to aquatic ecosystems
Authors: Håkanson L. 
Published: November 2008

Abstract
A key role of environmental management is to direct time and effort towards large environmental problems rather than towards small ones. To do this, it is crucial to have a system of criteria to define, structure, analyse and rank the problems. Subjective viewpoints are, evidently, not sufficient. Fully objective scientific methods and results are generally only applicable for specific substances in specific contexts, generally at finer scales (the cell, specific organs, and the like) but rarely at the ecosystem scale, which is the focus of this approach. The Potential Ecological Risk (PER) approach presented here is generic and could be applied to most types of ecosystems in most regions. The elements of the approach are: (1) definition of ecosystem boundaries, (2) definition of operational effect variables related to a defined chemical threat, (3) ecometric analysis (effect-load-sensitivity analysis), (4) integration (or summation) over impact area, and (5) integration (or summation) over impact time. Effect-load-sensitivity analysis is an important part of the PER approach. Case studies are used to provide examples for the major chemical threats to Swedish lakes and coastal ecosystems, acidification, eutrophication and toxic contamination of mercury, radiocaesium and chlorinated organics. Based on relative values, the ranking gives: Acidification of freshwater ecosystems (700) &gt; eutrophication of coastal ecosystems (560) &gt; eutrophication of lakes (300) &gt; mercury contamination of lakes (240) &gt; contamination of chlorinated organics of Swedish coastal areas in the Baltic (220) &gt; radiocaesium contamination of lakes (70).
Changes in relative abundance, variability, and stability of fish assemblages of Eastern Lake Ontario and the Bay of Quinte—the value of long-term community sampling
Authors: Casselman J.M. , Scott K.A. , Brown D.M. , Robinson C.J. 
Published: November 2008

Abstract
Intensive long-term index sampling of the fish communities of eastern Lake Ontario (outlet basin—gill netting, 1958–98, average annual effort 16.3 km of netting; bottom trawling, 1972–98, 23.0 km; Bay of Quinte—bottom trawling, 1972–98, 12.8 km) provided extensive summer catch data that we used to calculate indices to assess annual relative abundance, variability, and a combination of the two to reflect stability, or status. One of the unique and valuable attributes of these long-term data sets is that they use a community-assessment approach, which includes ecologically important small species and values the data on all species equally. These valuable series confirm that during the past decade, most major species in both the lake and bay have undergone a dramatic, somewhat synchronous change, unprecedented in almost three decades, including the catastrophic winterkills of the late 1970s. Abundance increased to record-high levels in the late 1980s and early 1990s, then decreased abruptly, two years earlier in small species (rainbow smelt, alewife and slimy scalpia) than large ones (lake trout, lake whitefish and walleye). The period of pivotal change was 1991–1993, coinciding with a significant decrease in water temperature from a period of six abnormally warm years, 1986–1991 (Apr.–Sept.—18.7°C), to three abnormally cold years, 1992–1994 (17.3°C). Temperature decrease from 1991 to 1992 (2.1°C) was the most extreme in four decades. Intensive rehabilitative stocking of lake trout, commencing in the mid-1970s, has helped restructure and mature the cold-water community to a point where large species were at record-high levels in the late 1980s and early 1990s, creating increasing prey demand that required maximum prey production; this was possible in the recent high-temperature regime (late 1980s) but was not sustainable in the low-temperature regime that followed. After 1992, large species lost condition, more dead fish were observed, and abundance decreased. This low-temperature perturbation induced a successional setback (enjuvenation event) that should be only temporary in the overall maturity of the ecosystem. However, recent colonization by dreissenids, which are inducing biological oligotrophication, could compound this.
Concentration and distribution of chlorinated phenolic compounds in Fraser River suspended sediment
Authors: Sekela M. , Brewer R. , Baldazzi C. , Moyle G. , Tuominen T. 
Published: November 2008

Abstract
The concentration of chlorophenolic compounds in suspended sediments was determined at four sites located on the upper Fraser River in British Columbia, Canada. One site was located upstream from the five pulp mills on the Fraser River, while the remaining three sites were located downstream from these mills. Suspended sediment samples were collected using a continuous flow centrifuge during the fall low flow and winter (under ice) periods. Nineteen chlorophenolic compounds were detected in samples collected from the downstream sites, with 4,5-dichlorocatechol, 3,4,5-trichlorocatechol and 3,4,5,6-tetrachlorocatechol measured in the highest concentrations. Samples collected under winter low flow conditions consistently had higher concentrations of chlorophenolics than samples collected under fall flow conditions. This is likely the result of a decrease in both the river flow and the background suspended sediment concentration during the winter low flow period.