20,273 research outputs found
Acaricide resistance and genetic affinities of some selected populations of Tetranychus urticae Koch in New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science (Horticultural) in Entomology at Massey University
A study of resistance to acaricides in a number of populations of the two-spotted spider mite, Tetranychus urticae, in New Zealand had been carried out. Natural genetic and cytoplasmic incompatibilities between populations were also investigated with a view to possible biological control of the pest. Facets of acaricide resistance that were studied included multi-resistance, cross-resistance, negatively correlated resistance and the inheritance of resistance. Chemicals used included an organophosphate representative (parathion-methyl), a carbamate (formetanate), an ungrouped compound (tricyclohexyltin hydroxide) and an organochlorine (dicofol). Cross-resistance was demonstrated between parathion-methyl and formetanate in five populations obtained from widely separate areas of New Zealand. The resistance to parathion of three strains was found to be inherited as a single dominant character and transmissible by both sexes. Cytoplasmic factors (or nucleo-cytoplasmic interactions) and minor genes were found to contribute slightly to the expression of total resistance. No resistance to tricyclohexyltin hydroxide (Plictran) and dicofol (Kelthane) was detected. High degrees of incompatibility (haploid egg lethality) were observed in the hybrids of crosses between the various populations. Chromosomal rearrangements in balanced, heterozygous conditions, in conjunction with the cytoplasm, were considered to be important factors determining the interpopulational sterilities. The interpopulational incompatibility phenomenon was found to be multi-factorial and not associated with the resistance factor. The egg mortalities of some backcross series which remained constantly high in spite of several crossings, implicated that the introduction of normal males to a resistant mite population in an enclosed area (e.g. in a glasshouse) might be a worthwhile proposition in the integrated control of spider mites. Backcross hybrids, on allowing to multiply randomly, were capable of forming new gene combinations, leading consequently to the formation of new strains which were genetically different from the original parents used in the backcross series
Expectation adjustment in the housing market: insights from the Scottish auction system
This paper examines price expectation adjustment of house buyers and sellers to rapid changes in the housing market using data from Scotland where houses are sold through 'first-price sealed-bid' auctions. These auctions provide more information on market signals, incentives and the behaviour of market participants than private treaty sales. This paper therefore provides a theoretical framework for analysing revealed preference data generated from these auctions. We specifically focus on the analysis of the selling to asking price difference, the 'bid-premium'. The bid-premium is shown to be affected by expectations of future price movements, market duration and high bidding frequency. The bid-premium reflects consumers' expectations, adapting to market conditions more promptly than asking price setting behaviour and final sale prices. The volatile conditions of the recent housing market bubble are fully reflected in the bid-premium, whereas the asking and sale prices are much less prone to rapid movements
Evolutionary computation in dynamic and uncertain environments
This book can be accessed from the link below - Copyright @ 2007 Springer-Verla
Editorial to special issue on evolutionary computation in dynamic and uncertain environments
Copyright @ Springer Science + Business Media. All rights reserved
A Graph Model for Imperative Computation
Scott's graph model is a lambda-algebra based on the observation that
continuous endofunctions on the lattice of sets of natural numbers can be
represented via their graphs. A graph is a relation mapping finite sets of
input values to output values.
We consider a similar model based on relations whose input values are finite
sequences rather than sets. This alteration means that we are taking into
account the order in which observations are made. This new notion of graph
gives rise to a model of affine lambda-calculus that admits an interpretation
of imperative constructs including variable assignment, dereferencing and
allocation.
Extending this untyped model, we construct a category that provides a model
of typed higher-order imperative computation with an affine type system. An
appropriate language of this kind is Reynolds's Syntactic Control of
Interference. Our model turns out to be fully abstract for this language. At a
concrete level, it is the same as Reddy's object spaces model, which was the
first "state-free" model of a higher-order imperative programming language and
an important precursor of games models. The graph model can therefore be seen
as a universal domain for Reddy's model
Determinations of upper critical field in continuous Ginzburg-Landau model
Novel procedures to determine the upper critical field have been
proposed within a continuous Ginzburg-Landau model. Unlike conventional
methods, where is obtained through the determination of the smallest
eigenvalue of an appropriate eigen equation, the square of the magnetic field
is treated as eigenvalue problems so that the upper critical field can be
directly deduced. The calculated from the two procedures are
consistent with each other and in reasonably good agreement with existing
theories and experiments. The profile of the order parameter associated with
is found to be Gaussian-like, further validating the methodology
proposed. The convergences of the two procedures are also studied.Comment: Revtex4, 8 pages, 4 figures, references modified, figures and table
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Hope as a Source of Resilience in Later Adulthood
This research provided a preliminary investigation of how variations in trait and state hope are associated with positive adaptation to stress in later adulthood. Trait hope and neuroticism were measured by questionnaires and state hope, stress, and negative emotions were assessed daily for 45 days. Results from multilevel random coefficient modeling analyses suggested that daily hope provides protective benefits by keeping negative emotions low, while also contributing to adaptive recovery from stress. The dynamic linkages between daily hope, stress, and emotion were further moderated by individual differences in trait hope. Compared with those low in trait hope, high-hope individuals showed diminished stress reactivity and more effective emotional recovery
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