10,649 research outputs found
PERFECT SUBSTITUTES: A NOTE ON THE ALCHIAN-ALLEN HYPOTHESIS
Alchian and Allen hypothesized that a country will export high rather than low quality goods. Here we show that if the inherent attributes of the commodities are identical the country will only export the high-quality good.transport costs, patterns of trade, product quality, International Relations/Trade, F1,
A study of factors related to over-achievers and under-achievers of average ability at the elementary level.
Thesis (Ed.M.)--Boston Universit
General linear and functor cohomology over finite fields
In recent years, there has been considerable success in computing Ext-groups
of modular representations associated to the general linear group by relating
this problem to one of computing Ext-groups in functor categories. In this
paper, we extend our ability to make such Ext-group calculations by
establishing several fundamental results. Throughout this paper, we work over
fields of positive characteristic p.Comment: 66 pages, published version, abstract added in migratio
The short-lived MATα2 transcriptional regulator is ubiquitinated in vivo
The substrates of ubiquitin-dependent proteolytic pathways include both damaged or otherwise abnormal proteins and undamaged proteins that are naturally short-lived. Few specific examples of the latter class have been identified, however. Previous work has shown that the cell type-specific MAT-alpha-2 repressor of the yeast Saccharomyces cerevisiae is an extremely short-lived protein. We now demonstrate that alpha-2 is conjugated to ubiquitin in vivo. More than one lysine residue of alpha-2 can be joined to ubiquitin, and some of the ubiquitin moieties form a Lys48-linked multiubiquitin chain. Overexpression of degradation-impaired ubiquitin variants was used to show that at least a significant fraction of alpha-2 degradation is dependent on its ubiquitination
Reduction of dynamical biochemical reaction networks in computational biology
Biochemical networks are used in computational biology, to model the static
and dynamical details of systems involved in cell signaling, metabolism, and
regulation of gene expression. Parametric and structural uncertainty, as well
as combinatorial explosion are strong obstacles against analyzing the dynamics
of large models of this type. Multi-scaleness is another property of these
networks, that can be used to get past some of these obstacles. Networks with
many well separated time scales, can be reduced to simpler networks, in a way
that depends only on the orders of magnitude and not on the exact values of the
kinetic parameters. The main idea used for such robust simplifications of
networks is the concept of dominance among model elements, allowing
hierarchical organization of these elements according to their effects on the
network dynamics. This concept finds a natural formulation in tropical
geometry. We revisit, in the light of these new ideas, the main approaches to
model reduction of reaction networks, such as quasi-steady state and
quasi-equilibrium approximations, and provide practical recipes for model
reduction of linear and nonlinear networks. We also discuss the application of
model reduction to backward pruning machine learning techniques
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