1,738 research outputs found
Next-to-next-to-leading-order epsilon expansion for a Fermi gas at infinite scattering length
We extend previous work on applying the epsilon-expansion to universal
properties of a cold, dilute Fermi gas in the unitary regime of infinite
scattering length. We compute the ratio xi = mu/epsilon_F of chemical potential
to ideal gas Fermi energy to next-to-next-to-leading order (NNLO) in
epsilon=4-d, where d is the number of spatial dimensions. We also explore the
nature of corrections from the order after NNLO.Comment: 28 pages, 14 figure
Enriched model categories and presheaf categories
We collect in one place a variety of known and folklore results in enriched
model category theory and add a few new twists. The central theme is a general
procedure for constructing a Quillen adjunction, often a Quillen equivalence,
between a given V-model category and a category of enriched presheaves in V,
where V is any good enriching category. For example, we rederive the result of
Schwede and Shipley that reasonable stable model categories are Quillen
equivalent to presheaf categories of spectra (alias categories of module
spectra) under more general hypotheses. The technical improvements and
modifications of general model categorical results given here are applied to
equivariant contexts in a pair of sequels, where we indicate various directions
of application.Comment: 45 pages. v4. A number of relatively small changes and updates from
the previous version, intended to address the most recent referee's report.
The most significant change is the addition of section 4.5, which discusses
Muro's work on arranging for a cofibrant uni
Models of G-spectra as presheaves of spectra
Let G be a finite group. We give Quillen equivalent models for the category
of G-spectra as categories of spectrally enriched functors from explicitly
described domain categories to nonequivariant spectra. Our preferred model is
based on equivariant infinite loop space theory applied to elementary
categorical data. It recasts equivariant stable homotopy theory in terms of
point-set level categories of G-spans and nonequivariant spectra. We also give
a more topologically grounded model based on equivariant Atiyah duality.Comment: 38 pages. v4. A number of relatively small changes and corrections.
The introduction has been rewritten in response to suggestions from a
referee. To make this paper more self-contained, section 4 on enriched model
categories of G-spectra has been added. A new section 5 addresses a minor
error in the previous version
Critical Exponents of the pure and random-field Ising models
We show that current estimates of the critical exponents of the
three-dimensional random-field Ising model are in agreement with the exponents
of the pure Ising system in dimension 3 - theta where theta is the exponent
that governs the hyperscaling violation in the random case.Comment: 9 pages, 4 encapsulated Postscript figures, REVTeX 3.
Inhibition of pancreatic cancer cell growth in vitro by the tyrphostin group of tyrosine kinase inhibitors.
Tyrphostins are a group of low molecular weight synthetic inhibitors of protein tyrosine kinases (PTK). The intracellular domains of the receptors for epidermal growth factor (EGF), transforming growth factor-alpha (TGF-alpha), insulin-like growth factor 1 (IGF-1) possess PTK activity. Since EGF, TGF-alpha and IGF-1 are considered to play an important role in the proliferation of pancreatic cancer cells, we studied the effects of tyrphostins on the growth of three human pancreatic cancer cell lines (MiaPaCa-2, Panc-1 and CAV). The tyrphostins AG17, T23 and T47 all inhibited EGF and serum-stimulated DNA synthesis. AG17 was found to be the most potent of these agents and caused a dose-dependent but reversible inhibition of cell growth. Furthermore using an immunoblotting procedure we also found AG17 to inhibit EGF-induced tyrosine phosphorylation in the MiaPaCa-2 cell line. Tyrosine kinase inhibitors may prove to be useful agents for the treatment of pancreatic cancer
Human pancreatic cancer cell lines do not express receptors for somatostatin.
The in vivo administration of somatostatin (SS) or its analogues is capable of suppressing the growth of pancreatic cancer in experimental animals. We examined the effects of SS-14 and its analogue RC-160 on the in vitro growth of two human pancreatic cancer cell lines MiaPaCa-2 and Panc-1 stimulated with epidermal growth factor (EGF) or insulin-like growth factor 1 (IGF-1). Neither SS-14 nor RC-160 inhibited the growth of either cell line. In contrast RC-160 did inhibit the EGF-stimulated growth of a rat pancreatic cancer cell line AR42J. Binding studies with 125I-Tyr11 somatostatin revealed the presence of a single class of high affinity binding sites with a Kd of 0.20 +/- 0.05 nM and a Bmax of 2.1 +/- 0.26 pmoles mg-1 protein on AR42J but not displaceable binding was observed on MiaPaCa-2 or Panc-1. We conclude that lack of receptors accounts for the failure of SS-14 and RC-160 to influence the growth of human pancreatic cancer in vitro. These results, taken together with other findings, lead us to question the therapeutic efficacy of somatostatin and its analogues as mono-therapy in the treatment of human pancreatic cancer
Grain and plant protein types fed to weaned piglets influence the apparent digestibility of carbohydrates and crude protein when measured at the terminal ileum
Diets based on cooked white rice fed to weaned piglets have a higher apparent ileal digestibility of starch than diets based on wheat (Pluske et al., 2007). The diets based on cooked white rice have used predominately animal sources of protein, however in Europe these are banned or excluded by retailer's specifications (except for milk proteins), and plant proteins are widely used instead. This study examined the interactive effects of cereal types and plant protein types on the apparent ileal digestibility of protein and carbohydrates to test the proposition that suitable sources of plant protein could ensure high digestibility coefficients in the small intestine
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