3,744 research outputs found
Nonmonotonic behavior of resistance in a superconductor-Luttinger liquid junction
Transport through a superconductor-Luttinger liquid junction is considered.
When the interaction in the Luttinger liquid is repulsive, the resistance of
the junction with a sufficiently clean interface shows nonmonotonic
temperature- or voltage-dependence due to the competition between the
superconductivity and the repulsive interaction. The result is discussed in
connection with recent experiments on single-wall carbon nanotubes in contact
with superconducting leads.Comment: Revtex4, 2 eps figure files, slightly revised from an earlier version
submitted to PRL on 2001.12.
Normal heat conduction in one dimensional momentum conserving lattices with asymmetric interactions
The heat conduction behavior of one dimensional momentum conserving lattice
systems with asymmetric interparticle interactions is numerically investigated.
It is found that with certain degree of interaction asymmetry, the heat
conductivity measured in nonequilibrium stationary states converges in the
thermodynamical limit, in clear contrast to the well accepted viewpoint that
Fourier's law is generally violated in low dimensional momentum conserving
systems. It suggests in nonequilibrium stationary states the mass gradient
resulted from the asymmetric interactions may provide an additional phonon
scattering mechanism other than that due to the nonlinear interactions.Comment: 4 pages, 4 figure
Identification of lipid droplet structure-like/resident proteins in Caenorhabditis elegans.
The lipid droplet (LD) is a cellular organelle that stores neutral lipids in cells and has been linked with metabolic disorders. Caenorhabditis elegans has many characteristics which make it an excellent animal model for studying LDs. However, unlike in mammalian cells, no LD structure-like/resident proteins have been identified in C. elegans, which has limited the utility of this model for the study of lipid storage and metabolism. Herein based on three lines of evidence, we identified that MDT-28 and DHS-3 previously identified in C. elegans LD proteome were two LD structure-like/resident proteins. First, MDT-28 and DHS-3 were found to be the two most abundant LD proteins in the worm. Second, the proteins were specifically localized to LDs and we identified the domains responsible for this targeting in both proteins. Third and most importantly, the depletion of MDT-28 induced LD clustering while DHS-3 deletion reduced triacylglycerol content (TAG). We further characterized the proteins finding that MDT-28 was ubiquitously expressed in the intestine, muscle, hypodermis, and embryos, whereas DHS-3 was expressed mainly in intestinal cells. Together, these two LD structure-like/resident proteins provide a basis for future mechanistic studies into the dynamics and functions of LDs in C. elegans
Quantification of white matter cellularity and damage in preclinical and early symptomatic Alzheimer\u27s disease
Interest in understanding the roles of white matter (WM) inflammation and damage in the pathophysiology of Alzheimer disease (AD) has been growing significantly in recent years. However, in vivo magnetic resonance imaging (MRI) techniques for imaging inflammation are still lacking. An advanced diffusion-based MRI method, neuro-inflammation imaging (NII), has been developed to clinically image and quantify WM inflammation and damage in AD. Here, we employed NII measures in conjunction with cerebrospinal fluid (CSF) biomarker classification (for β-amyloid (Aβ) and neurodegeneration) to evaluate 200 participants in an ongoing study of memory and aging. Elevated NII-derived cellular diffusivity was observed in both preclinical and early symptomatic phases of AD, while disruption of WM integrity, as detected by decreased fractional anisotropy (FA) and increased radial diffusivity (RD), was only observed in the symptomatic phase of AD. This may suggest that WM inflammation occurs earlier than WM damage following abnormal Aβ accumulation in AD. The negative correlation between NII-derived cellular diffusivity and CSF Aβ42 level (a marker of amyloidosis) may indicate that WM inflammation is associated with increasing Aβ burden. NII-derived FA also negatively correlated with CSF t-tau level (a marker of neurodegeneration), suggesting that disruption of WM integrity is associated with increasing neurodegeneration. Our findings demonstrated the capability of NII to simultaneously image and quantify WM cellularity changes and damage in preclinical and early symptomatic AD. NII may serve as a clinically feasible imaging tool to study the individual and composite roles of WM inflammation and damage in AD. Keywords: Inflammation, White matter damage, Diffusion basis spectrum imaging, Neuro-inflammation imaging, Cerebrospinal fluid, Preclinical Alzheimer disease, Early symptomatic Alzheimer disease, Magnetic resonance imagin
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