110,653 research outputs found
Multi-scale Modeling Approach to Acoustic Emission during Plastic Deformation
We address the long standing problem of the origin of acoustic emission
commonly observed during plastic deformation. We propose a frame-work to deal
with the widely separated time scales of collective dislocation dynamics and
elastic degrees of freedom to explain the nature of acoustic emission observed
during the Portevin-Le Chatelier effect. The Ananthakrishna model is used as it
explains most generic features of the phenomenon. Our results show that while
acoustic emission bursts correlated with stress drops are well separated for
the type C serrations, these bursts merge to form nearly continuous acoustic
signals with overriding bursts for the propagating type A bands.Comment: 4 pages, 6 figure
Anomalous transport and phonon renormalization in a chain with transverse and longitudinal vibrations
We study thermal transport in a chain of coupled atoms, which can vibrate in
longitudinal as well as transverse directions. The particles interact through
anharmonic potentials upto cubic order. The problem is treated quantum
mechanically. We first calculate the phonon frequencies self-consistently
taking into account the anharmonic interactions. We show that for all the
modes, frequencies must have linear dispersion with wave-vector for small
irrespective of their bare dispersions. We then calculate the phonon
relaxation rates , where is the polarization index of the
mode, in a self-consistent approximation based on second order perturbation
diagrams. We find that the relaxation rate for the longitudinal phonon,
, while that for the transverse phonon
. The consequence of these results on the thermal
conductivity of a chain of particles is that
Unparticle effects in Supernovae cooling
Recently H. Georgi suggested that a scale invariant unparticle
sector with an infrared fixed point at high energy can couple
with the SM matter via a higher-dimensional operator suppressed by a high
cut-off scale. Intense phenomenological search of this unparticle sector in the
collider and flavour physics context has already been made. Here we explore
it's impact in cosmology, particularly it's possible role in the supernovae
cooling. We found that the energy-loss rate (and thus the cooling) is strongly
dependent on the effective scale \LdaU and the anomalous dimension \dU of this
unparticle theory.Comment: 9 pages, 2 figures, text is modified, references updated and version
accepted for publication in Phys. Rev.
RPB4 and pathogenesis of diabetes
Obesity is an important risk factor for a number of chronic diseases that impose a huge burden on individuals and society. Recently it has become clear that adipose tissue-secreted products may play a significant role in mediating many obesity-related diseases including diabetes. Thus, in addition to being an energy depot, the adipocyte is a highly active cell, secreting a plethora of factors with profound effects on a number of organs and systems. The study of these factors and their endocrine effects has become a rapidly evolving and dynamic area of endocrinology. One paradigm for explaining the deleterious effects of adipokines is related to the sheer increase in adipose tissue mass in obesity. When preadipocytes differentiate to become mature adipocytes, they acquire the ability to synthesize numerous proteins, including cytokines, growth factors, and hormones that are involved in overall energy homeostasis and various paracrine effects. In health, these proteins do not spill over significantly into the circulation. In obesity, the massive increase in fat mass leads to a significant increase in circulation of many adipose tissue secreted factors that may have pathogenic effects. For example, the increase in circulating angiotensin II in obesity is related at least in part due to excess adiposity and may mediate hypertension (1). In recent years, adipose tissue has been found to be a major source of many proteins that may directly contribute to vascular injury, diabetes, and atherogenesis (2). These proinflammatory adipokines include TNF-α, IL-6, leptin, plasminogen activator inhibitor-1, angiotensinogen, and resistin, among many others. In contrast, the adipokine adiponectin confers protection against inflammation, atherogenesis, and obesity-linked insulin resistance
Continuous Functional Calculus for Quaternionic Bounded Normal Operators
In this article we give an approach to define continuous functional calculus
for bounded quaternionic normal operators defined on a right quaternionic
Hilbert space.Comment: Submitted to a journal. There was a gap in the previous version. We
have corrected it and stated all the results for bounded cas
Crystal structure of 4-aminobenzoic acid-4-methylpyridine (1/1)
The authors wish to acknowledge the SAIF, IIT, Madras, for the data collection.Peer reviewe
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