bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pattern matching with abstract data types
Authors: Burton F. Warren , Cameron Robert D 
Published: November 2008

AbstractPattern matching in modern functional programming languages is tied to the representation of data. Unfortunately, this is incompatible with the philosophy of abstract data types.Two proposals have been made to generalize pattern matching to a broader class of types. The laws mechanism of Miranda allows pattern matching with non-free algebraic data types. More recently, Wadler proposed the concept of views as a more general solution, making it possible to define arbitrary mappings between a physical implementation and a view supporting pattern matching. Originally, it was intended to include views in the new standard lazy functional programming language Haskell.Laws and views each offer important advantages, particularly with respect to data abstraction. However, if not used with great care, they also introduce serious problems in equational reasoning. As a result, laws have been removed from Miranda and views were not included in the final version of Haskell.We propose a third approach which unifies the laws and views mechanisms while avoiding their problems. Philosophically, we view pattern matching as a bundling of case recognition and component selection functions instead of a method for inverting data construction. This can be achieved by removing the implied equivalence between data constructors and pattern constructors. In practice, we allow automatic mapping into a view but not out of the view. We show that equational reasoning can still be used with the resulting system. In fact, equational reasoning is easier, since there are fewer hidden traps.
A paradigmatic object-oriented programming language: Design, static typing and semantics
Authors: Bruce Kim B. 
Published: November 2008

AbstractTo illuminate the fundamental concepts involved in object-oriented programming languages, we describe the design of TOOPL, a paradigmatic, statically-typed, functional, object-oriented programming language which supports classes, objects, methods, hidden instance variables, subtypes and inheritance.It has proven to be quite difficult to design such a language which has a secure type system. A particular problem with statically type checking object-oriented languages is designing typechecking rules which ensure that methods provided in a superclass will continue to be type correct when inherited in a subclass. The type-checking rules for TOOPL have this feature, enabling library suppliers to provide only the interfaces of classes with actual executable code, while still allowing users to safely create subclasses. To achieve greater expressibility while retaining type-safety, we choose to separate the inheritance and subtyping hierarchy in the language.The design of TOOPL has been guided by an analysis of the semantics of the language, which is given in terms of a model of the F-bounded second-order lambda calculus with fixed points at both the element and type level. This semantics supports the language design by providing a means to prove that the type-checking rules are sound, thus guaranteeing that the language is type-safe.While the semantics of our language is rather complex, involving fixed points at both the element and type level, we believe that this reflects the inherent complexity of the basic features of object-oriented programming languages. Particularly complex features include the implicit recursion inherent in the use of the keyword, self, to refer to the current object, and its corresponding type, MyType. The notions of subclass and inheritance introduce the greatest semantic complexities, whereas the notion of subtype is more straightforward to deal with. Our semantic investigations lead us to recommend caution in the use of inheritance, since small changes to method definitions in subclasses can result in major changes to the meanings of the other methods of the class.
Principal signatures for higher-order program modules
Authors: Tofte Mads 
Published: November 2008

AbstractIn this paper we present a language for programming with higher-order modules. The language HML is based on Standard ML in that it provides structures, signatures and functors. In HML, functors can be declared inside structures and specified inside signatures; this is not possible in Standard ML. We present an operational semantics for the static semantics of HML signature expressions, with particular emphasis on the handling of sharing. As a justification for the semantics, we prove a theorem about the existence of principal signatures. This result is closely related to the existence of principal type schemes for functional programming languages with polymorphism.
A system of constructor classes: overloading and implicit higher-order polymorphism
Authors: Jones Mark P. 
Published: November 2008

AbstractThis paper describes a flexible type system that combines overloading and higher-order polymorphism in an implicitly typed language using a system of constructor classes—a natural generalization of type classes in Haskell. We present a range of examples to demonstrate the usefulness of such a system. In particular, we show how constructor classes can be used to support the use of monads in a functional language. The underlying type system permits higher-order polymorphism but retains many of the attractive features that have made Hindley/Milner type systems so popular. In particular, there is an effective algorithm that can be used to calculate principal types without the need for explicit type or kind annotations. A prototype implementation has been developed providing, amongst other things, the first concrete implementation of monad comprehensions known to us at the time of writing.
Combinators for parsing expressions
Authors: Hill Steve 
Published: November 2008

AbstractThis paper describes a scheme for constructing parsers based on the top-down combinator approach. In particular, it describes a set of combinators for parsing expressions described by ambiguous grammars with precedence and associativity rules. The new combinators embody the mechanical grammar manipulations typically employed to remove left-recursion and hence help to avoid the possibility of a non-terminating parser. A number of approaches to the problem are described—the most elegant and efficient method is based on continuation passing. As a practical demonstration, a parser for the expression part of the C programming language is presented. The expression combinators are general, and may be constructed from any suitable set of top-down combinators. A comparison with parser generators shows that the combinator approach is most applicable for rapid development.
λν, a calculus of explicit substitutions which preserves strong normalisation
Authors: Benaissa Zine-El-Abidine , Briaud Daniel , Lescanne Pierre , Rouyer-Degli Jocelyne 
Published: November 2008

AbstractExplicit substitutions were proposed by Abadi, Cardelli, Curien, Hardin and Lévy to internalise substitutions into λ-calculus and to propose a mechanism for computing on substitutions. λν is another view of the same concept which aims to explain the process of substitution and to decompose it in small steps. It favours simplicity and preservation of strong normalisation. This way, another important property is missed, namely confluence on open terms. In spirit, λν is closely related to another calculus of explicit substitutions proposed by de Bruijn and called CλξΦ. In this paper, we introduce λν, we present CλξΦ in the same framework as λν and we compare both calculi. Moreover, we prove properties of λν; namely λν correctly implements β reduction, λν is confluent on closed terms, i.e. on terms of classical λ-calculus and on all terms that are derived from those terms, and finally λν preserves strong normalisation in the following sense: strongly β normalising terms are strongly λν normalising.
π-RED+ An interactive compiling graph reduction system for an applied λ-calculus
Authors: Gärtner Dietmar , Kluge Werner E. 
Published: November 2008

AbstractThis paper describes a compiling graph reduction system which realizes the reduction semantics of a fully-fledged applied λ-calculus. High-level functional programs are conceptually executed as sequences of program transformations governed by full β-reductions. They may be carried out step-by-step, and intermediate programs may be displayed in high-level notation, rendering the system suitable for interactive program design, high-level debugging, and also for teaching basic programming language concepts and language interpretation. Run-time efficiency for production runs is achieved by means of an abstract stack machine ASM which serves as an intermediate level of code generation. It employs multiple stacks for reasonably fast function calls, optimized tail-end recursions, and earliest possible releases of subgraphs that are no longer needed. The ASM involves an interpreter if and only if potential naming conflicts need to be resolved when reducing partial function applications.
Altersabhängigkeit dopplersonographisch ermittelter Flußgeschwindigkeiten in den Hirnarterien von Neugeborenen und Säuglingen
Authors: Rupprecht Th. , Deeg K. H. , Zeilinger G. 
Published: November 2008

Bei 121 gesunden Frühgeborenen, Neugeborenen und Säuglingen (Alter 1-30 Tage, Untersuchungsgewicht 1070-3750 g) wurden mit Hilfe der gepulsten DopplerSonographie die Strömungsgeschwindigkeiten in der Arteria cerebri anterior, der Arteria carotis interna und der Arteria basilaris gemessen.Alle Untersuchungen wurden mit dem Computer-Sonographie-Gerät Acuson 128, mit einem 5-MHz-Schallkopf, durchgeführt.Die maximale systolische, die endsystolische, die enddiastolische und die mittlere Flußgeschwindigkeit wurden aus dem Doppler-Frequenzspektrum ermittelt. Aus den Flußgeschwindigkeiten wurden ein Pulsatilitätsund ein Widerstands-Index errechnet. Es zeigte sich ein deutlicher linearer Anstieg aller Fluzßgeschwindigkeiten mit dem Lebensalter als Ausdruck der reifebedingt ansteigenden Hirnperfusion, während sich die berechneten Indices als altersunabhängig erwiesen. Für alle gemessenen Werte wurden Normalbereiche in Abhängigkeit vom Lebensalter angegeben.
Limnological characteristics of three aquatic systems of the pre-amazonian floodplain, Baixada Maranhense (Maranhão, Brazil)
Authors: Ibañez M.S.R. , Cavalcante P.R.S. , Costa Neto J.P. , Barbieri R. , Pontes J.P. , Santana S.C.C. , Serra C.L.M. , Nakamoto N. , Mitamura O. 
Published: November 2008

AbstractPreliminary information is provided on physical and chemical characteristics of three aquatic systems in the pre-amazonian floodplain, Baixada Maranhense: Pindaré (Viana Lake) and the Pericumã and Turiaçu rivers. Emphasis is given to the nutrients analyzed spectrophotometrically from the bottom sediments of Viana Lake. The water bodies differ from each other with respect to conductivity, total suspended solids and nutrient contents in the water, with higher values (except for total nitrogen) in the dry season. The main factors responsible for such differences, besides the annual flood, are the presence of macrophytes on Pericumã, riparian vegetation on Turiaçu (both systems with lotic characteristics) and water buffalo at Viana Lake. Bottom sediments with low nutrient concentrations at Viana Lake may be due to the rapid mineralization of organic matter in this lentic environment.
Tidal effects on nutrients and phytoplankton distribution in Bertioga Channel, São Paulo, Brazil
Authors: Gianesella S.M.F. , Saldanha-Corrêa F.M.P. , Teixeira C. 
Published: November 2008

Abstract
Dissolved nutrients and phytoplankton distribution in the Bertioga Channel, São Paulo State, were studied over a neap and a spring tide during the austral winter of 1991. Tidal influence and freshwater flow were the main forcing agents on the water column structure, nutrient availability and phytoplankton distribution as pointed out by the principal component analysis. The channel was vertically stratified during neap tide, but almost fully homogeneous during spring tide, especially in the flood phase. The inner area of the channel had high nutrient concentrations (up to 25 μM ammonium) and low dissolved oxygen saturation (minimum 20%). Phytoplankton biomass, measured as chlorophyll-a concentration, was low (maximum, 4.5 mg m−3) considering the high nutrient availability. The highest chlorophyll-a levels were associated with waters of coastal origin and flood periods. The phytoplankton community was dominated by phytoflagellates but the contribution of diatoms became very significant during spring tide. The major microphytoplankton forms were Skeletonema costatum and Pseudonitzschia species. The noticeable presence of freshwater species (Pinnularia, Synedra and Scenedesmus species), indicated the important role of freshwater inflow in the composition of local phytoplankton community. Data suggest that the high flushing rates and hydrodynamic instability at Bertioga Channel accounted for the low phytoplankton biomass observed in the environment.
Effect on the planktonic community of the chemical program used to control water hyacinth (Eichhornia crassipes) in Guadalupe Dam, Mexico
Authors: Lugo A. , Bravo-Inclán L.A. , Alcocer J. , Gaytán M.L. , Oliva Ma.G. , Sánchez Ma.del R. , Chávez M. , Vilaclara G. 
Published: November 2008

Abstract
Guadalupe Dam is a reservoir located into the Metropolitan area of Mexico City, which had been infested with water hyacinth (Eichhornia crassipes) for more than 12 years. In 1993 a management program was conducted in the reservoir. The main activities included the use of aquatic herbicides and mechanical control. The goal of this study was to monitor the composition and fluctuation of the planktonic community during the chemical control program. Five sampling stations were selected. Six samplings were made during the period of herbicides applications (July to November 1993) and one sampling more, used as control, was performed four months after the last application (March 1994). Herbicides diquat and 2,4-D amine were used in the chemical control program. Variables measured included temperature, dissolved oxygen, pH, chlorophyll a and numbers of phytoplankton, ciliates, rotifers, cladocerans and copepods. The reservoir is eutrophic, with high concentrations of chlorophyll a and low values of Secchi disc depth. Thermally, the dam seems to be warm monomictic. The infestation of aquatic weeds at the beginning of the program reached 95% of surface area. Two main effects of the herbicide application were observed. The first was the direct toxic effect of the chemicals on the growth and density of phytoplanktonic species, which lead to a reduction in zooplankton density related to food shortage. The second effect was indirect caused by the decomposing hyacinths which depleted dissolved oxygen concentrations. The oxygen deficit greatly affected the biological community. Although the chemical control program of Guadalupe Dam water hyacinth had a notable effect on the planktonic community, it recovered promptly. After the weed control program, the Guadalupe dam remained eutrophic. Although water hyacinth was eliminated, it was replaced by a large phytoplankton bloom.
Spatial variations in trace metal and stable isotope content of autochthonous organisms and sediments in the river Po system (Italy)
Authors: Camusso M. , Balestrini R. , Martinotti W. , Arpini M. 
Published: November 2008

Abstract
Variations in (a) carbon and nitrogen stable isotope composition (as δ13C and δ15N), and (b) trace metal content of sediments and biota (algae, invertebrates and fish) were investigated at four sites along the river Po (from the middle reaches to the delta) and one site in the coastal Adriatic area influenced by the river. The aim was to begin accumulating a database to help interpret differences in the accumulation of toxic substances in biota and sediments, elucidating how food sources and feeding strategies change between areas of the system differing in terms of anthropogenic influence and distance from the river mouth. C content and δ13C and δ15N were determined on biological tissue and sediment samples using a continuous flow isotope ratio mass spectrometer. Trace metal concentrations were assayed by electrothermal (Cd, Cu, Cr, Ni, Pb) or flame (Zn) atomic absorption spectrometry after acid digestion. Hg was assayed on solid samples on an automated mercury analyser using the vapour generation technique. In the sediments, depletions of the 13C isotope at the post-Lambro site (downstream) relative to the upstream Lambro site were indicative of the significant pollutant input from this tributary to the Po. Mercury, cadmium and zinc concentrations in sediments were two-to-three times higher downstream compared to upstream. Differences in carbon and nitrogen isotope signatures in fish species among the two Lambro sites and the last stretch of the Po indicated variations in the type of food and primary carbon sources. Only for chromium were concentrations significantly higher in fish muscle from the post Lambro site than from upstream of the Lambro or the last reaches of the Po. Mean levels of cadmium and zinc in the muscle of omnivorous fish at the four river sites were low and similar (&lt; 0.01 to 0.02 μg g-1 for Cd, 22–31 μg g-1 for zinc), while between-site differences were found for the other metals. Only for mercury did bioaccumulation reflect trophic level movement.
A case analysis of strategies in ecotourism development
Authors: Masberg B.A. , Morales N. 
Published: November 2008

Abstract
Ecotourism is a form of tourism which focuses on contributing to the preservation of natural and cultural resources while promoting economic contribution to local communities. Certain factors have been identified in the literature to optimize both preservation and economic contribution, but the strategies to accomplish these factors have not been defined. The purpose of this research was to identify through case analysis how each of the success factors in ecotourism development (i.e. an integrated approach, planning and a slow start, education and training, maximize local benefits, and evaluation and feedback) have been implemented in ecotourism cases. A series of ecotourism cases were analyzed. The success factors were identified and the strategies described under each factor were recorded. The data collected for all cases were pooled for each of the success factors and a matrix of five success factors with the corresponding strategies was created. Strategies that appeared as ‘recommended’ in the cases were not included in the analysis. The results indicated that factors and strategies differed. Within each factor there is no predominant strategy. Success factors should be re-evaluated and factors identified using an ecosystem management approach which puts the health of the environment as the foundation of tourism development. Standards need to be set and then strategies assigned to maintain standards for preservation and economic well-being.
Induction of systemic resistance in Arabidopsis thaliana in response to a culture filtrate from a plant growth‐promoting fungus, Phoma sp. GS8‐3
Authors: Sultana F. , Hossain Md. M. , Kubota M. , Hyakumachi M. 
Published: November 2008

AbstractThe plant growth‐promoting fungus (PGPF), Phoma sp. GS8‐3, isolated from a zoysia grass rhizosphere, is capable of protecting cucumber plants against virulent pathogens. This fungus was investigated in terms of the underlying mechanisms and ability to elicit systemic resistance in Arabidopsis thaliana. Root treatment of Arabidopsis plants with a culture filtrate (CF) from Phoma sp. GS8‐3 elicited systemic resistance against the bacterial speck pathogen Pseudomonas syringae pv. tomato DC3000 (Pst), with restricted disease development and inhibited pathogen proliferation. Pathway‐specific mutant plants, such as jar1 (jasmonic acid insensitive) and ein2 (ethylene insensitive), and transgenic NahG plants (impaired in salicylate signalling) were protected after application of the CF, demonstrating that these pathways are dispensable (at least individually) in CF‐mediated resistance. Similarly, NPR1 interference in npr1 mutants had no effect on CF‐induced resistance. Gene expression studies revealed that CF treatment stimulated the systemic expression of both the SA‐inducible PR‐1 and JA/ET‐inducible PDF1.2 genes. However, pathogenic challenge to CF‐treated plants was associated with potentiated expression of the PR‐1 gene and down‐regulated expression of the PDF1.2 gene. The observed down‐regulation of the PDF1.2 gene in CF‐treated plants indicates that there may be cross‐talk between SA‐ and JA/ET‐dependent signalling pathways during the pathogenic infection process. In conclusion, our data suggest that CF of Phoma sp. GS8‐3 induces resistance in Arabidopsis in a manner where SA and JA/ET may play a role in defence signalling.
Anucleated cryptophyte vestiges in the gonyaulacalean dinoflagellates Amylax buxus and Amylax triacantha (Dinophyceae)
Authors: Koike Kazuhiko , Takishita Kiyotaka 
Published: November 2008

SUMMARYCryptophyte vestiges showing selective digestion of nuclei were found in the gonyaulacalean dinoflagellates Amylax buxus (Balech) Dodge and Amylax triacantha (Jörgensen) Sournia. They emitted bright yellow‐orange fluorescence (590‐nm emission) under epifluorescent microscopy and possessed U‐shaped plastids, suggesting the vestiges were active in photosynthesis. Under transmission electron microscopy, the plastid was characterized by a loose arrangement of two to three thylakoid stacks and included a stalked pyrenoid, as in the cryptophyte genus Teleaulax. Indeed, molecular data based on the plastid small‐subunit rRNA gene demonstrated that the vestiges in Amylax originated from Teleaulax amphioxeia. The stolen plastid (kleptoplastids) in Dinophysis is also derived from this cryptophyte species. However, in sharp contrast to Dinophysis, the plastid of the vestige in Amylax was surrounded by a double layer of plastid endoplasmic reticulum, and within the periplastidal area, a nucleomorph was retained. The vestiges also possessed mitochondria with characteristic plate‐like cristae, but lost the cell‐surface structure. The phagocytotic membrane of the dinoflagellates seemed to surround the cryptophytes right after the incorporation, but the membrane itself would probably be digested eventually. Remarkably, only one cryptophyte cell among 14 vestiges in a cell of A. buxus had a nucleus. This is the first recording of possible kleptoplastidy in gonyaulacalean dinoflagellates, and documents the strategy of a dinoflagellate involving the selective elimination of the cryptophyte nucleus.
Comptes rendus
Authors: Holmer Nils M. , Malmmberg Bertil 
Published: November 2008

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