18,798 research outputs found
Using tabu search and genetic algorithms in mathematics research
This paper discusses an ongoing project which uses computational heuristic search techniques such as tabu search and genetic algorithms as a tool for mathematics research. We discuss three ways in which such search techniques can be useful for mathematicians: in nding counterexamples to conjectures, in enumerating examples, and in nding sequences of transformations between two objects which are conjectured to be related. These problem-types are discussed using examples from topology
A pollen identification expert system ; an application of expert system techniques to biological identification : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Computer Science Massey University
The application of expert systems techniques to biological identification has been investigated and a system developed which assists a user to identify and count air-borne pollen grains. The present system uses a modified taxonomic data matrix as the structure for the knowledge base. This allows domain experts to easily assess and modify the knowledge using a familiar data structure. The data structure can be easily converted to rules or a simple frame-based structure if required for other applications. A method of ranking the importance of characters for identifying each taxon has been developed which assists the system to quickly narrow an identification by rejecting or accepting candidate taxa. This method is very similar to that used by domain experts
TECHNOLOGICAL CHANGE AND THE PRODUCTIVITY SLOWDOWN IN FIELD CROPS: UNITED STATES, 1939-78
In the past four decades, productivity in United States field crops has been transformed by the mechanical and fertilizer revolutions. Since input data are typically not available by crop, most investigators of productivity have been at the aggregate level. This paper developps a simultaneous equation, partial adjustment model of the demand of inputs, which generates estimates of the technical change parameters for wheat, corn, soybeans, and cotton. These estimates allow comparisons of the factor saving biases in technical change, leading to a novel test of the induced innovation hypothesis and the suggestion that the productivity slowdown may yet affect agriculture in the United States.Research and Development/Tech Change/Emerging Technologies,
Is it Time for Computational Creativity to Grow Up and Start being Irresponsible?
A recent definition of computational creativity has em- phasised that computational creativity systems should âtake on certain responsibilitiesâ for generating creative behaviour. This paper examines the notion of responsibilities in that definition, and looks at a number of aspects of the creative act and its context that might play a role in that responsibility, with an emphasis on artistic and musical creativity. This problematises the seemingly simple distinction between systems that have responsibilities for creative activity and those which support or provide tools for creativity. The paper con- cludes with a discussion of an alternative approach to the subject, which argues that the responsibility for creative action is typically diffused through a complex human/computer system, and that a âsystems thinkingâ approach to locating computational creativity might ask better questions than one that tries to pin creative responsibility to a particular agent
Chemical information matters: an e-Research perspective on information and data sharing in the chemical sciences
Recently, a number of organisations have called for open access to scientific information and especially to the data obtained from publicly funded research, among which the Royal Society report and the European Commission press release are particularly notable. It has long been accepted that building research on the foundations laid by other scientists is both effective and efficient. Regrettably, some disciplines, chemistry being one, have been slow to recognise the value of sharing and have thus been reluctant to curate their data and information in preparation for exchanging it. The very significant increases in both the volume and the complexity of the datasets produced has encouraged the expansion of e-Research, and stimulated the development of methodologies for managing, organising, and analysing "big data". We review the evolution of cheminformatics, the amalgam of chemistry, computer science, and information technology, and assess the wider e-Science and e-Research perspective. Chemical information does matter, as do matters of communicating data and collaborating with data. For chemistry, unique identifiers, structure representations, and property descriptors are essential to the activities of sharing and exchange. Open science entails the sharing of more than mere facts: for example, the publication of negative outcomes can facilitate better understanding of which synthetic routes to choose, an aspiration of the Dial-a-Molecule Grand Challenge. The protagonists of open notebook science go even further and exchange their thoughts and plans. We consider the concepts of preservation, curation, provenance, discovery, and access in the context of the research lifecycle, and then focus on the role of metadata, particularly the ontologies on which the emerging chemical Semantic Web will depend. Among our conclusions, we present our choice of the "grand challenges" for the preservation and sharing of chemical information
Latitudinal Differentiation in the Effects of the Toxic Dinoflagellate Alexandrium spp. on the Feeding and Reproduction of Populations of the Copepod Acartia Hudsonica
Blooms of the dinoflagellate Alexandrium spp. increase in their frequency, toxicity and historical presence with increasing latitude from New Jersey (USA) to the GaspĂ© peninsula (Canada). Biogeographic variation in these blooms results in differential exposure of geographically separate copepod populations to toxic Alexandrium. We hypothesize that the ability of copepods to feed and reproduce on toxic Alexandrium should be higher in copepods from regions that are frequently exposed to toxic Alexandrium blooms. We tested this hypothesis with factorial common environment experiments in which female adults of the copepod Acartia hudsonica from five separate populations ranging from New Jersey to New Brunswick were fed toxic and non-toxic strains of Alexandrium, and the non-toxic flagellate Tetraselmis sp. Consistent with the hypothesis, when fed toxic Alexandrium we observed significantly higher ingestion and egg production rates in the copepods historically exposed to toxic Alexandrium blooms relative to copepods from regions in which Alexandrium is rare or absent. Such differences among copepod populations were not observed when copepods were fed non-toxic Alexandrium or Tetraselmis sp. These results were also supported by assays in which copepods from populations both historically exposed and naıÌve to toxic Alexandrium blooms were fed mixtures of toxic Alexandrium and Tetraselmis sp. Two-week long experiments demonstrated that when copepods from populations naıÌve to toxic Alexandrium were fed a toxic strain of Alexandrium they failed to acclimate, such that their ingestion rates remained low throughout the entire two-week period. The differences observed among populations suggest that local adaptation of populations of A. hudsonica from Massachusetts (USA) to New Brunswick (Canada) has occurred, such that some populations are resistant to toxic Alexandrium
Comparison of the Functional and Numerical Responses of Resistant versus Non-resistant Populations of the Copepod Acartia Hudsonica Fed the Toxic Dinoflagellate Alexandrium Tamarense
The functional and numerical responses of grazers are key pieces of information in predicting and modeling predatorâprey interactions. It has been demonstrated that exposure to toxic algae can lead to evolved resistance in grazer populations. However, the influence of resistance on the functional and numerical response of grazers has not been studied to date. Here, we compared the functional and numerical responses of populations of the copepod Acartia hudsonica that vary in their degree of resistance to the toxic dinoflagellate Alexandrium tamarense. In common environment experiments carried out after populations had been grown under identical conditions for several generations, female copepods were offered solutions containing different concentrations of either toxic A. tamarense or the non-toxic green flagellate Tetraselmis sp. ranging from âŒ25 to 500 ÎŒgC Lâ1, and ingestion and egg production rates were measured. Throughout most of the range of concentrations of the toxic diet, copepod populations that had been historically exposed to toxic blooms of Alexandrium exhibited significantly higher ingestion and egg production rates than populations that had little or no exposure to these blooms. In contrast, there were no significant differences between populations in ingestion or egg production for the non-toxic diet. Hence, the between population differences in functional and numerical response to A. tamarense were indeed related to resistance. We suggest that the effect of grazer toxin resistance should be incorporated in models of predator and toxic prey interactions. The potential effects of grazer toxin resistance in the development and control of Alexandrium blooms are illustrated here with a simple simulation exercise
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