2,000 research outputs found
Comparative Analysis of the Major Polypeptides from Liver Gap Junctions and Lens Fiber Junctions
Gap junctions from rat liver and fiber junctions from bovine lens have similar septilaminar profiles when examined by thin-section electron microscopy and differ only slightly with respect to the packing of intramembrane particles in freeze-fracture images. These similarities have often led to lens fiber junctions being referred to as gap junctions. Junctions from both sources were isolated as enriched subcellular fractions and their major polypeptide components compared biochemically and immunochemically. The major liver gap junction polypeptide has an apparent molecular weight of 27,000, while a 25,000-dalton polypeptide is the major component of lens fiber junctions. The two polypeptides are not homologous when compared by partial peptide mapping in SDS. In addition, there is not detectable antigenic similarity between the two polypeptides by immunochemical criteria using antibodies to the 25,000-dalton lens fiber junction polypeptide. Thus, in spite of the ultrastructural similarities, the gap junction and the lens fiber junction are comprised of distinctly different polypeptides, suggesting that the lens fiber junction contains a unique gene product and potentially different physiological properties
Prompt fluorescence from biphenylene in liquid solution: Absence of detectable S2→S0 fluorescence and its implications, vibrational structure and polarization of S1→S0 fluorescence, and orientational relaxation of molecules in S1.
The prompt emission from S0→S2 photoexcited biphenylene in 3-methylpentane has been investigated. No prompt S2→S0 fluorescence has been observed. The implications of this negative result are discussed. It is shown that lengthening of the radiative lifetime of S2 due to intermediate strong S2-S1 coupling is the likely cause of the absence of detectable S2-S0 fluorescence. The observable resonance Raman lines of biphenylene can be assigned to totally symmetric vibrations. The position of S1,0 is determined by a vibrational analysis of the S1→S0 fluorescence. The polarization degree P of the S1→S0 fluorescence is positive. From the dependence of P on temperature and viscosity, orientational relaxation times of biphenylene in S1 are determined with Perrin's formula
Elastic Deformation of Polycrystals
We propose a framework to model elastic properties of polycrystals by
coupling crystal orientational degrees of freedom with elastic strains. Our
model encodes crystal symmetries and takes into account explicitly the strain
compatibility induced long-range interaction between grains. The coupling of
crystal orientation and elastic interactions allows for the rotation of
individual grains by an external load. We apply the model to simulate uniaxial
tensile loading of a 2D polycrystal within linear elasticity and a system with
elastic anharmonicities that describe structural phase transformations. We
investigate the constitutive response of the polycrystal and compare it to that
of single crystals with crystallographic orientations that form the
polycrystal.Comment: 4 pages, 4 ps figure
A high-reflectivity high-Q micromechanical Bragg-mirror
We report on the fabrication and characterization of a micromechanical
oscillator consisting only of a free-standing dielectric Bragg mirror with high
optical reflectivity and high mechanical quality. The fabrication technique is
a hybrid approach involving laser ablation and dry etching. The mirror has a
reflectivity of 99.6%, a mass of 400ng, and a mechanical quality factor Q of
approximately 10^4. Using this micromirror in a Fabry Perot cavity, a finesse
of 500 has been achieved. This is an important step towards designing tunable
high-Q high-finesse cavities on chip.Comment: 3 pages, 2 figure
Dark Sectors with Mass Thresholds Face Cosmological Datasets
Interacting dark sectors may undergo changes in the number of their
relativistic species during the early universe, due to a mass threshold
(similar to changes in the Standard Model bath), and in doing so affect the
cosmic history. When such changes occur close to recombination, i.e., for
, the stringent bound on the effective number of
neutrino species, , can be relaxed and the value of the Hubble
expansion rate inferred from Cosmic Microwave Background (CMB)
observations raised. We search for such sectors (with and without mass
thresholds) in the latest cosmological datasets, including the full-shape (FS)
of BOSS DR12 galaxy power spectrum. We perform a detailed analysis, accounting
for the choice of prior boundaries and additionally exploring the possible
effects of dark sector interactions with (a fraction of) the dark matter. We
find at 95% C.L. with (without) a
mass threshold. While a significantly larger Hubble rate is achieved in this
scenario, , the overall fit to CMB+FS data does not
provide a compelling advantage over the CDM model. Furthermore, we
find that dark matter interactions with the dark sector do not significantly
improve the (matter fluctuations) tension with respect to the
CDM model. Our work provides model-independent constraints on
(decoupled) dark sectors with mass thresholds around the eV scale.Comment: 18 + 18 pages, 38 figures and table
TADA – a Machine Learning Tool for Functional Annotation based Prioritisation of Putative Pathogenic CNVs
Few methods have been developed to investigate copy number variants (CNVs) based on their predicted pathogenicity. We introduce TADA, a method to prioritise pathogenic CNVs through assisted manual filtering and automated classification, based on an extensive catalogue of functional annotation supported by rigourous enrichment analysis. We demonstrate that our classifiers are able to accurately predict pathogenic CNVs, outperforming current alternative methods, and produce a well-calibrated pathogenicity score. Our results suggest that functional annotation-based prioritisation of pathogenic CNVs is a promising approach to support clinical diagnostics and to further the understanding of mechanisms controlling the disease impact of larger genomic alterations
Self-cooling of a micro-mirror by radiation pressure
We demonstrate passive feedback cooling of a mechanical resonator based on
radiation pressure forces and assisted by photothermal forces in a high-finesse
optical cavity. The resonator is a free-standing high-reflectance micro-mirror
(of mass m=400ng and mechanical quality factor Q=10^4) that is used as
back-mirror in a detuned Fabry-Perot cavity of optical finesse F=500. We
observe an increased damping in the dynamics of the mechanical oscillator by a
factor of 30 and a corresponding cooling of the oscillator modes below 10 K
starting from room temperature. This effect is an important ingredient for
recently proposed schemes to prepare quantum entanglement of macroscopic
mechanical oscillators.Comment: 11 pages, 9 figures, minor correction
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