ALBERT — All Library Books, journals and Electronic Records Telegrafenberg

1

Electronic Resource

An experimental analysis of the bandit problem (1997)

Banks, Jeffrey ; Olson, Mark ; Porter, David

Springer

Economic theory 10 (1997), S. 55-77

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ISSN: 1432-0479

Keywords: JEL Classification Numbers: C91 ; C73 ; D81 ; D83.

Source: Springer Online Journal Archives 1860-2000

Topics: Economics

Notes: Summary. We investigate, in an experimental setting, the behavior of single decision makers who at discrete time intervals over an “infinite” horizon may choose one action from a set of possible actions where this set is constant over time, i.e. a bandit problem. Two bandit environments are examined, one in which the predicted behavior should always be myopic (the two-armed bandit) and the other in which the predicted behavior should never be myopic (the one-armed bandit). We also investigate the comparative static predictions as the underlying parameters of the bandit environments are changed. The aggregate results show that the behavior in the two bandit environments are quantitatively different and in the direction of the theoretical predictions.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/s001990050146

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2

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Certification of a Frozen Mussel Tissue Standard Reference Material (SRM 1974a) for Trace Organic Constituents (1997)

Schantz, M. M. ; Demiralp, Rabia ; Greenberg, Robert R. ; [et al.]

Springer

Fresenius' journal of analytical chemistry 358 (1997), S. 431-440

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ISSN: 1432-1130

Source: Springer Online Journal Archives 1860-2000

Topics: Chemistry and Pharmacology

Notes: Abstract NIST SRM 1974a, Organics in Mussel Tissue (Mytilus edulis), has been issued as a frozen tissue homogenate with certified mass fractions for 15 polycyclic aromatic hydrocarbons (PAHs), 20 polychlorinated biphenyl (PCB) congeners, and 7 chlorinated pesticides. Noncertified mass fractions are provided for an additional 18 PAHs, 4 PCB congeners, 4 chlorinated pesticides, 28 inorganic constituents, 16 aliphatic hydrocarbons, and methylmercury. The mass fractions for the measured PAHs range from approximately 1 μg/kg to 164 μg/kg dry mass while the mass fractions for the measured PCB congeners range from approximately 3 μg/kg to 150 μg/kg dry mass.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/s002160050442

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3

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Certification of three mussel tissue standard reference materials (SRM) for methylmercury and total mercury content (1997)

Donais, M. K. ; Saraswati, Rajananda ; Mackey, Elizabeth ; [et al.]

Springer

Fresenius' journal of analytical chemistry 358 (1997), S. 424-430

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ISSN: 1432-1130

Source: Springer Online Journal Archives 1860-2000

Topics: Chemistry and Pharmacology

Notes: Abstract SRM 1974a, Organics in Mussel Tissue (Mytilus edulis); SRM 2974, Organics in Mussel Tissue (freeze-dried); and SRM 2976, Mussel Tissue (trace elements and methylmercury) have been recently certified for methylmercury and total mercury content. Three independent analytical procedures were used to determine the certified methylmercury concentrations. Four independent procedures combined with data from two intercomparison exercises were used to determine the certified total mercury concentrations. These materials are the first certified metal speciation environmental SRMs issued by the National Institute of Standards and Technology.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/s002160050441

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4

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Differential regulation of the plasmid-encoded genes in the Shigella flexneri virulence regulon (1997)

Porter, M. E. ; Dorman, C. J.

Springer

Molecular genetics and genomics 256 (1997), S. 93-103

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ISSN: 1617-4623

Keywords: Key words Virulence genes ; Environmental regulation ; H-NS ; DNA Superceiling ; Shigella flexneric

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract Expression of the Shigella flexneri virulence gene regulon is controlled by multiple environmental signals acting through a regulatory cascade. The primary regulator is VirF, which is a positive regulator of the secondary regulatory gene virB and the structural gene icsA. The product of the virB gene in turn activates transcription of the genes coding for the invasion proteins, and for the type III secretion system which promotes export of the invasion proteins to the bacterial cell surface. The genes making up the regulon were studied in their native locations on the 230-kb virulence plasmid. Transcriptional control was detected at each level of the regulatory cascade. A gearing effect was detected upon thermal induction of transcription in the regulon, with the virF gene being induced by about two fold, virB by 10-fold and the structural genes by 100-fold. In addition, each gene studied displayed individual characteristics in its response to stimuli such as growth medium osmolarity, pH, variations in DNA superhelicity and the presence or absence of H-NS. The primary regulatory gene virF, displayed loose regulation under standard laboratory growth conditions. Regulation was tighter at the secondary regulator virB, while control of structural gene expression was tighter still. It is proposed that this regulatory pattern ensures that energetically wasteful expression of the structural genes under inappropriate conditions is avoided while allowing the regulatory genes to be expressed sufficiently under non-permissive conditions to ensure a rapid response to inducing conditions when these arise. Once induced, fine tuning of the response can be achieved through the different sensitivities of the individual regulon members to external stimuli.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/s004380050550

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5

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Fundamental Laws and Assumptions of Software Maintenance (1997)

Porter, Adam A.

Springer

Empirical software engineering 2 (1997), S. 119-131

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ISSN: 1573-7616

Keywords: Empirical Studies ; Software Maintenance ; Theory Development ; Interdisciplinary Research

Source: Springer Online Journal Archives 1860-2000

Topics: Computer Science

Notes: Abstract Researchers must pay far more attention to discovering and validating the principles that underlie software maintenance and evolution. This was one of the major conclusions reached during the International Workshop on Empirical Studies of Software Maintenance. This workshop, held in November 1996 in Monterey, California, brought together an international group of researchers to discuss the successes, challenges and open issues in software maintenance and evolution. This article documents the discussion of the subgroup on fundamental laws and assumptions of software maintenance. The participants of this group included researchers in software engineering, the behavioral sciences, information systems and statistics. Their main conclusion was that insufficient effort has been paid to synthesizing research conjectures into validated theories and that this problem has slowed progress in software maintenance. To help support this vision they identified the following supporting conclusions. (1) need to develop a genuine scientific approach—more than just using empirical methods, (2) other disciplines can help, (3) need to explore a wider range of approaches to empirical studies, (4) need to study both evolution and maintenance.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1023/A:1009793015685

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6

Electronic Resource

Situated Knowledge and the Virtual Science and Industry Museum: Problems in the Social-Technical Interface (1997)

Hemmings, Terry ; Randall, Dave ; Francis, Dave ; [et al.]

Springer

Archives and Museum Informatics 11 (1997), S. 147-164

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ISSN: 1573-7500

Keywords: virtual museum ; user/visitor ; technology ; WWW (World Wide Web) CSCW (Computer Supported Cooperative Work) ; HCI (Human Computer Interaction) Internet ; ICT (Information and Communication Technology) culture ; sociology ; ethnomethodology ; situated knowledge ; local practices ; classification

Source: Springer Online Journal Archives 1860-2000

Topics: Information Science and Librarianship , Nature of Science, Research, Systems of Higher Education, Museum Science

Notes: Abstract The Museum is a perspicuous site for analysing the complex interplay between social, organisational, cultural and political factors which have relevance to the design and use of ‘virtual’ technologies. Specifically, the introduction of virtual technologies in museums runs up against the issue of the situated character of information use. Across a number of disciplines (anthropology, sociology, psychology, cognitive science) there is growing recognition of the ‘situatedness’ of knowledge and its importance for the design and use of technology. This awareness is fostered by the fact that technological developments are often associated with disappointing gains for users. The effective use of technology relies on the degree to which it can be embedded in or congruent with the ‘local’ practices of museum users. Drawing upon field research in two museums of science and technology, both of which are in the process of introducing virtual technologies and exploring the possibilities of on-line access, findings are presented which suggest that the success of such developments will depend on the extent to which they are informed by detailed understanding of practice-practices that are essentially socially constituted in the activities of museum visitors and the daily work of museum professionals.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1023/A:1009007316752

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7

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Phylogeny and Evolution of Selected Primates as Determined by Sequences of the ε-Globin Locus and 5′ Flanking Regions (1997)

Porter, Calvin A. ; Page, Scott L. ; Czelusniak, John ; [et al.]

Springer

International journal of primatology 18 (1997), S. 261-295

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ISSN: 1573-8604

Keywords: ceboids ; strepsirhines ; primate phylogeny ; ε-globin gene ; molecular evolution ; molecular clock

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract We studied phylogenetic relationships of 39 primate species using sequences of the ε-globin gene. For 13 species, we also included flanking sequences 5′ of this locus. Parsimony analyses support the association of tarsiers with the anthropoids. Our analysis of New World monkeys supports the model in which the callitrichines form a clade with Aotus, Cebus, and Saimiri, with Cebus and Saimiri being sister taxa. However, analysis of the 5′ flanking sequences did not support grouping the atelines with Callicebus and the pitheciins. Our data support the classification of platyrrhines into three families, Cebidae (consisting of Cebus, Saimiri, Aotus, and the callitrichines; Atelidae—the atelines; and Pitheciidae—Callicebus and the pithiciins. The strepsirhines form well-defined lemuroid and lorisoid clades, with the cheirogaleids (dwarf and mouse lemurs) and Daubentonia (aye-aye) in the lemuroids, and the aye-aye being the most anciently derived. These results support the hypothesis that nonhuman primates of Madagascar descended from a single lineage. Local molecular clock calculations indicate that the divergence of lemuroid and lorisoid lineages, and the earliest diversification of lemuroids, occurred during the Eocene. The divergence of major lorisoid lineages was probably considerably more recent, possibly near the Miocene–Oligocene boundary. Within hominoids some estimated dates differ somewhat from those found with more extensive noncoding sequences in the β-globin cluster.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1023/A:1026328804319

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8

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The response of the major crop and pasture pest, the red-legged earth mite (Halotydeus destructor) to pesticides: dose-response curves and evidence for tolerance (1997)

Hoffmann, Ary A. ; Porter, Stephanie ; Kovacs, Ingrid

Springer

Experimental and applied acarology 21 (1997), S. 151-162

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ISSN: 1572-9702

Keywords: H. destructor ; pesticides ; resistance ; tolerance ; bioassay

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract We describe an assay for testing the response of the adult red- legged earth mite, Halotydeus destructor, to pesticides. This assay is used to generate dose response curves for an organophosphate (omethoate) and an organochlorine (endosulphan) commonly used to control these mites, as well as a synthetic pyrethroid (alfamethrin). Comparisons of the populations from five sites around Victoria indicated tolerance to omethoate. A heritable basis for the tolerance was demonstrated by comparing the stocks after they had been reared under laboratory conditions for a generation. No tolerance of endosulphan was detected, although this chemical was not used heavily at any of the sites. Some tolerance of alfamethrin was also suggested. These results suggest that alternative methods for controlling this pest will eventually need to be considered.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1023/A:1018482502080

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9

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The effect of heat treatment on the tensileand creep behaviour of “neat” matrix Ti–22Al–23Nb (1997)

Smith, P. R ; Porter, W. J

Springer

Journal of materials science 32 (1997), S. 6215-6220

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ISSN: 1573-4803

Source: Springer Online Journal Archives 1860-2000

Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Notes: Abstract A study has been conducted to examine the effect of post-consolidation heat treatment on the longitudinal tensile and creep properties of an orthorhombic-based titanium aluminide, Ti–22Al–23Nb (a%), in neat matrix form. Heat-treatment parameters were selected such that they would be consistent with future inclusion into the consolidation cycle for the fabrication of continuously reinforced orthorhombic titanium matrix composites (O TMCs). The effects of heat treatment on microstructural evolution, including type and morphology of the phase constituents, was examined via scanning secondary electron microscopy and quantitative image analysis. Variations in microstructural features were correlated with resulting room-temperature tensile properties including: ultimate tensile strength, yield strength, total elongation and modulus, as well as isothermal creep response at 650°C/172 MPa.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1023/A:1018676808772

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