11,255 research outputs found
The Role of Erythropoietin-Derived Peptides in Tissue Protection
Erythropoietin (EPO), recognized as a tissue protective agent, can trigger anti-inflammatory and anti-apoptotic processes to delimit injury and promote repair by the binding tissue-protective receptor. However, only at a high dosage can EPO exert tissue protective effects, which simultaneously elicits some severe erythropoiesis-related side effects. Thus, the structural modification of EPO for the prevention of side effects is undoubtedly required. This chapter reviewed the development from EPO to its peptide derivatives with tissue protective efficacy. We also discussed are the therapeutic effects and limitations of each peptide, signaling pathways involved and the benefits for translation
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Simultaneously encoding movement and sEMG-based stiffness for robotic skill learning
Transferring human stiffness regulation strategies to robots enables them to effectively and efficiently acquire adaptive impedance control policies to deal with uncertainties during the accomplishment of physical contact tasks in an unstructured environment. In this work, we develop such a physical human-robot interaction (pHRI) system which allows robots to learn variable impedance skills from human demonstrations. Specifically, the biological signals, i.e., surface electromyography (sEMG) are utilized for the extraction of human arm stiffness features during the task demonstration. The estimated human arm stiffness is then mapped into a robot impedance controller. The dynamics of both movement and stiffness are simultaneously modeled by using a model combining the hidden semi-Markov model (HSMM) and the Gaussian mixture regression (GMR). More importantly, the correlation between the movement information and the stiffness information is encoded in a systematic manner. This approach enables capturing uncertainties over time and space and allows the robot to satisfy both position and stiffness requirements in a task with modulation of the impedance controller. The experimental study validated the proposed approach
Relating Gene Expression Evolution with CpG Content Changes
Background:
Previous studies have shown that CpG dinucleotides are enriched in a subset of promoters and the CpG content of promoters is positively correlated with gene expression levels. But the relationship between divergence of CpG content and gene expression evolution has not been investigated. Here we calculate the normalized CpG (nCpG) content in DNA regions around transcription start site (TSS) and transcription terminal site (TTS) of genes in nine organisms, and relate them with expression levels measured by RNA-seq. Results:
The nCpG content of TSS shows a bimodal distribution in all organisms except platypus, whereas the nCpG content of TTS only has a single peak. When the nCpG contents are compared between different organisms, we observe a different evolution pattern between TSS and TTS: compared with TTS, TSS exhibits a faster divergence rate between closely related species but are more conserved between distant species. More importantly, we demonstrate the link between gene expression evolution and nCpG content changes: up-/down- regulation of genes in an organism is accompanied by the nCpG content increase/decrease in their TSS and TTS proximal regions. Conclusions:
Our results suggest that gene expression changes between different organisms are correlated with the alterations in normalized CpG contents of promoters. Our analyses provide evidences for the impact of nCpG content on gene expression evolution
Differential and Difference Equations for Recurrence Coefficients of Orthogonal Polynomials with a Singularly Perturbed Laguerre-type Weight
We are concerned with the monic orthogonal polynomials with respect to a
singularly perturbed Laguerre-type weight. By using the ladder operator
approach, we derive a complicated system of nonlinear second-order difference
equations satisfied by the recurrence coefficients. This allows us to derive
the large asymptotic expansions of the recurrence coefficients. In
addition, we also obtain a system of differential-difference equations for the
recurrence coefficients
More on complexity of operators in quantum field theory
Recently it has been shown that the complexity of SU() operator is
determined by the geodesic length in a bi-invariant Finsler geometry, which is
constrained by some symmetries of quantum field theory. It is based on three
axioms and one assumption regarding the complexity in continuous systems. By
relaxing one axiom and an assumption, we find that the complexity formula is
naturally generalized to the Schatten -norm type. We also clarify the
relation between our complexity and other works. First, we show that our
results in a bi-invariant geometry are consistent with the ones in a
right-invariant geometry such as -local geometry. Here, a careful analysis
of the sectional curvature is crucial. Second, we show that our complexity can
concretely realize the conjectured pattern of the time-evolution of the
complexity: the linear growth up to saturation time. The saturation time can be
estimated by the relation between the topology and curvature of SU() groups.Comment: Modified the Sec. 4.1, where we offered a powerful proof: if (1) the
ket vector and bra vector in quantum mechanics contain same physics, or (2)
adding divergent terms to a Lagrangian will not change underlying physics,
then complexity in quantum mechanics must be bi-invariant
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