235 research outputs found
Evidence against the energetic cost hypothesis for the short introns in highly expressed genes
<p>Abstract</p> <p>Background</p> <p>In animals, the moss <it>Physcomitrella patens </it>and the pollen of <it>Arabidopsis thaliana</it>, highly expressed genes have shorter introns than weakly expressed genes. A popular explanation for this is selection for transcription efficiency, which includes two sub-hypotheses: to minimize the energetic cost or to minimize the time cost.</p> <p>Results</p> <p>In an individual human, different organs may differ up to hundreds of times in cell number (for example, a liver versus a hypothalamus). Considered at the individual level, a gene specifically expressed in a large organ is actually transcribed tens or hundreds of times more than a gene with a similar expression level (a measure of mRNA abundance per cell) specifically expressed in a small organ. According to the energetic cost hypothesis, the former should have shorter introns than the latter. However, in humans and mice we have not found significant differences in intron length between large-tissue/organ-specific genes and small-tissue/organ-specific genes with similar expression levels. Qualitative estimation shows that the deleterious effect (that is, the energetic burden) of long introns in highly expressed genes is too negligible to be efficiently selected against in mammals.</p> <p>Conclusion</p> <p>The short introns in highly expressed genes should not be attributed to energy constraint. We evaluated evidence for the time cost hypothesis and other alternatives.</p
Stability of Strutinsky Shell Correction Energy in Relativistic Mean Field Theory
The single-particle spectrum obtained from the relativistic mean field (RMF)
theory is used to extract the shell correction energy with the Strutinsky
method. Considering the delicate balance between the plateau condition in the
Strutinsky smoothing procedure and the convergence for the total binding
energy, the proper space sizes used in solving the RMF equations are
investigated in detail by taking 208Pb as an example. With the proper space
sizes, almost the same shell correction energies are obtained by solving the
RMF equations either on basis space or in coordinate space.Comment: 9 pages, 4 figure
Mixed State Entanglement for Holographic Axion Model
We study the mixed state entanglement in a holographic axion model. We find
that the holographic entanglement entropy (HEE), mutual information (MI) and
entanglement of purification (EoP) exhibit very distinct behaviors with system
parameters. The HEE exhibits universal monotonic behavior with system
parameters, while the behaviors of MI and EoP relate to the specific system
parameters and configurations. We find that MI and EoP can characterize mixed
state entanglement better than HEE since they are less affected by thermal
effects. Moreover, we argue that EoP is more suitable for describing mixed
state entanglement than MI. Because the MI of large configurations are still
dictated by the thermal entropy, while the EoP will never be controlled only by
the thermal effects.Comment: 20 pages, 13 figure
E2-AEN: End-to-End Incremental Learning with Adaptively Expandable Network
Expandable networks have demonstrated their advantages in dealing with
catastrophic forgetting problem in incremental learning. Considering that
different tasks may need different structures, recent methods design dynamic
structures adapted to different tasks via sophisticated skills. Their routine
is to search expandable structures first and then train on the new tasks,
which, however, breaks tasks into multiple training stages, leading to
suboptimal or overmuch computational cost. In this paper, we propose an
end-to-end trainable adaptively expandable network named E2-AEN, which
dynamically generates lightweight structures for new tasks without any accuracy
drop in previous tasks. Specifically, the network contains a serial of powerful
feature adapters for augmenting the previously learned representations to new
tasks, and avoiding task interference. These adapters are controlled via an
adaptive gate-based pruning strategy which decides whether the expanded
structures can be pruned, making the network structure dynamically changeable
according to the complexity of the new tasks. Moreover, we introduce a novel
sparsity-activation regularization to encourage the model to learn
discriminative features with limited parameters. E2-AEN reduces cost and can be
built upon any feed-forward architectures in an end-to-end manner. Extensive
experiments on both classification (i.e., CIFAR and VDD) and detection (i.e.,
COCO, VOC and ICCV2021 SSLAD challenge) benchmarks demonstrate the
effectiveness of the proposed method, which achieves the new remarkable
results
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