34 research outputs found
High order amplitude equation for steps on creep curve
We consider a model proposed by one of the authors for a type of plastic
instability found in creep experiments which reproduces a number of
experimentally observed features. The model consists of three coupled
non-linear differential equations describing the evolution of three types of
dislocations. The transition to the instability has been shown to be via Hopf
bifurcation leading to limit cycle solutions with respect to physically
relevant drive parameters. Here we use reductive perturbative method to extract
an amplitude equation of up to seventh order to obtain an approximate analytic
expression for the order parameter. The analysis also enables us to obtain the
bifurcation (phase) diagram of the instability. We find that while
supercritical bifurcation dominates the major part of the instability region,
subcritical bifurcation gradually takes over at one end of the region. These
results are compared with the known experimental results. Approximate analytic
expressions for the limit cycles for different types of bifurcations are shown
to agree with their corresponding numerical solutions of the equations
describing the model. The analysis also shows that high order nonlinearities
are important in the problem. This approach further allows us to map the
theoretical parameters to the experimentally observed macroscopic quantities.Comment: LaTex file and eps figures; Communicated to Phys. Rev.
Non-viral systemic delivery of siRNA or antisense oligonucleotides targeted to Jun N-terminal kinase 1 prevents cellular hypoxic damage
Sphingosine 1-phosphate antagonizes human neutrophil apoptosis via p38 mitogen-activated protein kinase
Chryseomonas luteola from Bile Culture in an Adult Male with Severe Jaundice
A 60-year-old male was admitted in this hospital with severe jaundice, who had open cholecystectomy done 2 months ago. ERCP was performed and bile was sent for culture. It grew Chryseomonas luteola in pure culture. He underwent hepaticojejunostomy after 1 month. Total bilirubin improved gradually. His condition was stable on discharge. Prompt diagnosis of non-fermenters is required, as some of them are resistant to multiple antibiotics. Clinicians have to be made aware of the pathogenic role of C. luteola and its resistance to ampicillin and cephalosporins