1,081 research outputs found
The Morita equivalence between parametrized spectra and module spectra
We give a Quillen equivalence between May and Sigurdsson's model category of
parametrized spectra over BG, and Mandell, May, Schwede, and Shipley's model
category of modules over the orthogonal ring spectrum \Sigma^\infty_+ G, for
each topological group G. More generally, for a topological category C we
introduce an "aggregate" model structure on the category of diagrams of spectra
indexed by C, and prove that it is Quillen equivalent to spectra over BC. This
lifts several earlier results, and leads to a complete characterization of the
dualizable parametrized spectra, answering a question of May and Sigurdsson.Comment: 24 pages, to appear in Contemporary Mathematic
Infinite loop spaces and nilpotent K-theory
Using a construction derived from the descending central series of the free
groups, we produce filtrations by infinite loop spaces of the classical
infinite loop spaces , , , , , and
. We show that these infinite loop spaces are the zero
spaces of non-unital -ring spectra. We introduce the notion of
-nilpotent K-theory of a CW-complex for any , which extends the
notion of commutative K-theory defined by Adem-G\'omez, and show that it is
represented by , were is the -th term of
the aforementioned filtration of .
For the proof we introduce an alternative way of associating an infinite loop
space to a commutative -monoid and give criteria when it can be
identified with the plus construction on the associated limit space.
Furthermore, we introduce the notion of a commutative -rig and show
that they give rise to non-unital -ring spectra.Comment: To appear in Algebraic and geometric topolog
Diagram spaces, diagram spectra, and spectra of units
This article compares the infinite loop spaces associated to symmetric
spectra, orthogonal spectra, and EKMM S-modules. Each of these categories of
structured spectra has a corresponding category of structured spaces that
receives the infinite loop space functor \Omega^\infty. We prove that these
models for spaces are Quillen equivalent and that the infinite loop space
functors \Omega^\infty agree. This comparison is then used to show that two
different constructions of the spectrum of units gl_1 R of a commutative ring
spectrum R agree.Comment: 62 pages. The definition of the functor \mathbb{Q} is changed.
Sections 8, 9, 17 and 18 contain revisions and/or new materia
Inclusion of Host Quality Data Improves Predictions of Herbivore Phenology
Understanding the correspondence between ambient temperature and insect development is necessary to forecast insect phenology under novel environments. In the face of climate change, both conservation and pest control efforts require accurate phenological predictions. Here, we compare a suite of degree-day models to assess their ability to predict the phenology of a common, oligophagous butterfly, the silver-spotted skipper, Epargyreus clarus (Cramer) (Lepidoptera: Hesperiidae). To estimate model parameters, we used development time of eggs and larvae reared in the laboratory at six constant temperatures ranging from 8 to 38 °C and on two host plants of contrasting quality (kudzu and wisteria). We employed three approaches to determine the base temperature to calculate degree days: linear regression, modified reduced major axis regression, and application of a generic base temperature value of 10 °C, which is commonly used in the absence of laboratory data. To calculate the number of degree days required to complete a developmental stage, we used data from caterpillars feeding on high- and low-quality hosts, both in the field and in the laboratory. To test model accuracy, we predicted development time of seven generations of larvae reared in the field on the same host plants across 3 years (2014–2016). To compare performance among models, we regressed predicted vs. observed development time, and found that r2 values were significantly larger when accounting for host plant quality. The accuracy of development time predictions varied across the season, with estimates of the first two generations being more accurate than estimates of the third generation, when ambient temperatures dropped outside the range in which development rate and temperature have a linear relationship. Overall, we show that accounting for variation in host plant quality when calculating development time in the field is more important than the choice of the base temperature for calculating degree days
Effects of GABRA2 variation on physiological, psychomotor and subjective responses in the Alcohol Challenge Twin Study
Multiple reports have identified variation in the GABRA2 gene as contributing to the genetic susceptibility to alcohol dependence. However, both the mechanism behind this association, and the range of alcohol-related phenotypes affected by variation in this gene, are currently undefined. Other data suggest that the risk of alcohol dependence is increased by relative insensitivity to alcohol's intoxicating effects. We have therefore tested whether GABRA2 variation is associated with variation in the subjective and objective effects of a standard dose of alcohol in humans. Data on responses to alcohol from the Alcohol Challenge Twin Study (Martin et al., 1985) have been tested against allelic and haplotype information obtained by typing 41 single-nucleotide polymorphisms in or close to the GABRA2 gene. Nominally significant allelic associations (p < .05, without correction for multiple testing) were found for body sway, motor coordination, pursuit rotor and arithmetical computation tasks, and for the personality dimension of Neuroticism. Because of the large number of phenotypes tested, these possibly significant findings will need to be confirmed in further studies
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