1,999 research outputs found
A brief history of outbreaks of the Douglas-fir tussock moth, Hemerocampa pseudotsugata McD., in British Columbia
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Annotated list of forest insects of British Columbia, Part XIV, Polygonia, Nymphalis, and Limenitis (Nymphalidae)
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Annotated list of forest insects of British Columbia Part XII. Boarmiini and Melanolophiini (Geometridae)
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Annotated list of forest insects of British Columbia Part XIV, Ennominae (Geometridae)
The mature larvae of 57 species of forest geometrids are described briefly and their distribution and hosts, as determined from samples collected by personnel of the Forest Insect and Disease Survey, are given
A brief history of outbreaks of the Douglas-fir tussock moth, Hemerocampa pseudotsugata McD., in British Columbia
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The cardiomyocyte "redox rheostat": Redox signalling via the AMPK-mTOR axis and regulation of gene and protein expression balancing survival and death.
Reactive oxygen species (ROS) play a key role in development of heart failure but, at a cellular level, their effects range from cytoprotection to induction of cell death. Understanding how this is regulated is crucial to develop novel strategies to ameliorate only the detrimental effects. Here, we revisited the fundamental hypothesis that the level of ROS per se is a key factor in the cellular response by applying different concentrations of H2O2 to cardiomyocytes. High concentrations rapidly reduced intracellular ATP and inhibited protein synthesis. This was associated with activation of AMPK which phosphorylated and inhibited Raptor, a crucial component of mTOR complex-1 that regulates protein synthesis. Inhibition of protein synthesis by high concentrations of H2O2 prevents synthesis of immediate early gene products required for downstream gene expression, and such mRNAs (many encoding proteins required to deal with oxidant stress) were only induced by lower concentrations. Lower concentrations of H2O2 promoted mTOR phosphorylation, associated with differential recruitment of some mRNAs to the polysomes for translation. Some of the upregulated genes induced by low H2O2 levels are cytoprotective. We identified p21Cip1/WAF1 as one such protein, and preventing its upregulation enhanced the rate of cardiomyocyte apoptosis. The data support the concept of a "redox rheostat" in which different degrees of ROS influence cell energetics and intracellular signalling pathways to regulate mRNA and protein expression. This sliding scale determines cell fate, modulating survival vs death
A dynamically extending exclusion process
An extension of the totally asymmetric exclusion process, which incorporates
a dynamically extending lattice is explored. Although originally inspired as a
model for filamentous fungal growth, here the dynamically extending exclusion
process (DEEP) is studied in its own right, as a nontrivial addition to the
class of nonequilibrium exclusion process models. Here we discuss various
mean-field approximation schemes and elucidate the steady state behaviour of
the model and its associated phase diagram. Of particular note is that the
dynamics of the extending lattice leads to a new region in the phase diagram in
which a shock discontinuity in the density travels forward with a velocity that
is lower than the velocity of the tip of the lattice. Thus in this region the
shock recedes from both boundaries.Comment: 20 pages, 12 figure
Annotated list of forest insects of British Columbia Part XIV, Ennominae (Geometridae)
The mature larvae of 57 species of forest geometrids are described briefly and their distribution and hosts, as determined from samples collected by personnel of the Forest Insect and Disease Survey, are given
Chaos and unpredictability in evolutionary dynamics in discrete time
A discrete-time version of the replicator equation for two-strategy games is
studied. The stationary properties differ from that of continuous time for
sufficiently large values of the parameters, where periodic and chaotic
behavior replace the usual fixed-point population solutions. We observe the
familiar period-doubling and chaotic-band-splitting attractor cascades of
unimodal maps but in some cases more elaborate variations appear due to
bimodality. Also unphysical stationary solutions have unusual physical
implications, such as uncertainty of final population caused by sensitivity to
initial conditions and fractality of attractor preimage manifolds.Comment: 4 pages, 4 figure
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