5,211 research outputs found
High-efficiency cell concepts on low-cost silicon sheets
The limitations on sheet growth material in terms of the defect structure and minority carrier lifetime are discussed. The effect of various defects on performance are estimated. Given these limitations designs for a sheet growth cell that will make the best of the material characteristics are proposed. Achievement of optimum synergy between base material quality and device processing variables is proposed. A strong coupling exists between material quality and the variables during crystal growth, and device processing variables. Two objectives are outlined: (1) optimization of the coupling for maximum performance at minimal cost; and (2) decoupling of materials from processing by improvement in base material quality to make it less sensitive to processing variables
Significance of thermal fluctuations and hydrodynamic interactions in receptor-ligand mediated adhesive dynamics of a spherical particle in wall bound shear flow
The dynamics of adhesion of a spherical micro-particle to a ligand-coated
wall, in shear flow, is studied using a Langevin equation that accounts for
thermal fluctuations, hydrodynamic interactions and adhesive interactions.
Contrary to the conventional assumption that thermal fluctuations play a
negligible role at high Pclet numbers, we find that for particles
with low surface densities of receptors, rotational diffusion caused by
fluctuations about the flow and gradient directions aids in bond formation,
leading to significantly greater adhesion on average, compared to simulations
where thermal fluctuations are completely ignored. The role of wall
hydrodynamic interactions on the steady state motion of a particle, when the
particle is close to the wall, has also been explored. At high Pclet
numbers, the shear induced force that arises due to the stresslet part of the
Stokes dipole, plays a dominant role, reducing the particle velocity
significantly, and affecting the states of motion of the particle. The coupling
between the translational and rotational degrees of freedom of the particle,
brought about by the presence of hydrodynamic interactions, is found to have no
influence on the binding dynamics. On the other hand, the drag coefficient,
which depends on the distance of the particle from the wall, plays a crucial
role at low rates of bond formation. A significant difference in the effect of
both the shear force and the position dependent drag force, on the states of
motion of the particle, is observed when the Plet number is small.Comment: The manuscript has been accepted as an article in Physical Review E
Journa
A Systems Biology Approach towards Deciphering the Unfolded Protein Response in Huntington's Disease
Although the disease causing gene huntingtin has been known for some time, the exact cause of neuronal cell death during _Huntington's disease_ (HD) remains unknown. One potential mechanism contributing to the massive loss of neurons in HD brains might be the _Unfolded Protein Response_ (UPR) which is activated by accumulation of misfolded proteins in the endoplasmic reticulum (ER). As an adaptive response, UPR upregulates transcription of chaperones, temporarily attenuating new translation and activates protein degradation via the proteasome. However, at high levels of ER stress, UPR signalling can contribute to neuronal apoptosis.

Our primary aims include (a) construction of the UPR signalling network, (b) curation and bioinformatical identification of UPR target genes and finally (c) examination of HD gene expression data sets for UPR transcriptional signatures and differential regulation of UPR pathways.

The UPR signalling pathway is reconstructed based on literature review and using the "Unified Interactome database":http://www.unihi.org. Lists of UPR target genes detected by previous experiments or as predicted by computational analysis are compiled. This allows us to perform enrichment analysis for differential HD gene expression and to assess whether UPR expression signatures are prominent during HD pathogenesis.

Results: The canonical UPR pathway is complemented with additional protein interaction data allowing us to assess its embedding into the cellular context and to identify potential modifiers as well as novel drug targets.

Conclusions: The in depth systems biology analysis can give us valuable insights about the involvement of the UPR in HD.

The Unfolded Protein Response and its potential role in Huntington's disease
Huntington's disease (HD) is a progressive, neurodegenerative disease with fatal outcome. Although the disease-causing gene (huntingtin) has been known for some time, the exact cause of neuronal cell death is still unknown. One potential mechanism contributing to the massive loss of neurons in the brain of HD patients might be the unfolded protein response (UPR), which is activated by accumulation of misfolded proteins in the endoplasmatic reticulum (ER). As an adaptive response to counter-balance accumulation of un- or misfolded proteins, the UPR upregulates transcription of chaperones, temporarily attenuates new translation, and activates protein degradation via the proteasome. However, it is known that persistent ER stress and activated UPR can cause cell death by triggering of apoptosis. Nevertheless, the evidence linking UPR with HD progression remains inconclusive. Here, we present first analyses of UPR activation during HD based on available expression data. To elucidate the potential role of UPR as a disease-relevant process, we examine its connection to cell death and inflammatory processes. Due to the complexity of these molecular mechanisms, a systems biology approach was pursued
On associating Fast Radio Bursts with afterglows
A radio source that faded over six days, with a redshift of
host, has been identified by Keane et al. (2016) as the transient afterglow to
a fast radio burst (FRB 150418). We report follow-up radio and optical
observations of the afterglow candidate and find a source that is consistent
with an active galactic nucleus. If the afterglow candidate is nonetheless a
prototypical FRB afterglow, existing slow-transient surveys limit the fraction
of FRBs that produce afterglows to 0.25 for afterglows with fractional
variation, , and 0.07 for , at 95%
confidence. In anticipation of a barrage of bursts expected from future FRB
surveys, we provide a simple framework for statistical association of FRBs with
afterglows. Our framework properly accounts for statistical uncertainties, and
ensures consistency with limits set by slow-transient surveys.Comment: Accepted version (ApJL
Estimation and Determinants of Chronic Poverty in India : An Alternative Approach
The paper conceptualizes chronic poverty by using the spaces of income and nutrition and estimates its incidence among states and social groups. It also aims to improve our understanding of the determinant of chronic poverty by considering economic, demographic and social factors. It attempts to answer the following questions : How important a determinant of chronic poverty is household income? What factors inhibit escape from chronic poverty? How different are the other poor from chronic poor? The analysis uses the unit level NSS and NFHS data.Chrinic Poverty, India
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