157 research outputs found
Electronic energy band structure of solids Quarterly status report, 16 Mar. - 15 Jun. 1967
Piezoresistance and piezo-Hall effect in semiconducting strontium titanium oxid
Ideal Bose gas in fractal dimensions and superfluid He in porous media
Physical properties of ideal Bose gas with the fractal dimensionality between
D=2 and D=3 are theoretically investigated. Calculation shows that the
characteristic features of the specific heat and the superfluid density of
ideal Bose gas in fractal dimensions are strikingly similar to those of
superfluid Helium-4 in porous media. This result indicates that the geometrical
factor is dominant over mutual interactions in determining physical properties
of Helium-4 in porous media.Comment: 13 pages, 6 figure
Testing Lorentz invariance by use of vacuum and matter filled cavity resonators
We consider tests of Lorentz invariance for the photon and fermion sector
that use vacuum and matter-filled cavities. Assumptions on the wave-function of
the electrons in crystals are eliminated from the underlying theory and
accurate sensitivity coefficients (including some exceptionally large ones) are
calculated for various materials. We derive the Lorentz-violating shift in the
index of refraction n, which leads to additional sensitivity for matter-filled
cavities ; and to birefringence in initially isotropic media. Using published
experimental data, we obtain improved bounds on Lorentz violation for photons
and electrons at levels of 10^-15 and below. We discuss implications for future
experiments and propose a new Michelson-Morley type experiment based on
birefringence in matter.Comment: 15 pages, 8 table
Photogenerated Carriers in SrTiO3 Probed by Mid-Infrared Absorption
Infrared absorption spectra of SrTiO have been measured under
above-band-gap photoexcitations to study the properties of photogenerated
carriers, which should play important roles in previously reported photoinduced
phenomena in SrTiO. A broad absorption band appears over the entire
mid-infrared region under photoexcitation. Detailed energy, temperature, and
excitation power dependences of the photoinduced absorption are reported. This
photo-induced absorption is attributed to the intragap excitations of the
photogenerated carriers. The data show the existence of a high density of
in-gap states for the photocarriers, which extends over a wide energy range
starting from the conduction and valence band edges.Comment: 5 pages, 5 figures, submitted to J. Phys. Soc. Jp
Tuning of metal-insulator transition of two-dimensional electrons at parylene/SrTiO interface by electric field
Electrostatic carrier doping using a field-effect-transistor structure is an
intriguing approach to explore electronic phases by critical control of carrier
concentration. We demonstrate the reversible control of the insulator-metal
transition (IMT) in a two dimensional (2D) electron gas at the interface of
insulating SrTiO single crystals. Superconductivity was observed in a
limited number of devices doped far beyond the IMT, which may imply the
presence of 2D metal-superconductor transition. This realization of a
two-dimensional metallic state on the most widely-used perovskite oxide is the
best manifestation of the potential of oxide electronics
Lattice dynamics effects on small polaron properties
This study details the conditions under which strong-coupling perturbation
theory can be applied to the molecular crystal model, a fundamental theoretical
tool for analysis of the polaron properties. I show that lattice dimensionality
and intermolecular forces play a key role in imposing constraints on the
applicability of the perturbative approach. The polaron effective mass has been
computed in different regimes ranging from the fully antiadiabatic to the fully
adiabatic. The polaron masses become essentially dimension independent for
sufficiently strong intermolecular coupling strengths and converge to much
lower values than those tradition-ally obtained in small-polaron theory. I find
evidence for a self-trapping transition in a moderately adiabatic regime at an
electron-phonon coupling value of .3. Our results point to a substantial
independence of the self-trapping event on dimensionality.Comment: 8 pages, 5 figure
Concurrence of Danish Dementia and Cataract: Insights from the Interactions of Dementia Associated Peptides with Eye Lens α-Crystallin
Familial Danish Dementia (FDD) is an autosomal disease, which is distinguished by gradual loss of vision, deafness, progressive ataxia and dementia. Cataract is the first manifestation of the disease. In this article, we demonstrate a specific correlation between the poisoning of the chaperone activity of the rat eye lens α-crystallins, loss of lens transparency in organ culture by the pathogenic form of the Danish dementia peptide, i.e. the reduced Danish dementia peptide (redADan peptide), by a combination of ex vivo, in vitro, biophysical and biochemical techniques. The interaction of redADan peptide and lens crystallins are very specific when compared with another chaperone, HSP-70, underscoring the specificity of the pathogenic form of Danish dementia peptide, redADan, for the early onset of cataract in this disease
Common Genetic Variants Contribute to Risk of Transposition of the Great Arteries.
RATIONALE: Dextro-transposition of the great arteries (D-TGA) is a severe congenital heart defect which affects approximately 1 in 4,000 live births. While there are several reports of D-TGA patients with rare variants in individual genes, the majority of D-TGA cases remain genetically elusive. Familial recurrence patterns and the observation that most cases with D-TGA are sporadic suggest a polygenic inheritance for the disorder, yet this remains unexplored.
OBJECTIVE: We sought to study the role of common single nucleotide polymorphisms (SNPs) in risk for D-TGA.
METHODS AND RESULTS: We conducted a genome-wide association study in an international set of 1,237 patients with D-TGA and identified a genome-wide significant susceptibility locus on chromosome 3p14.3, which was subsequently replicated in an independent case-control set (rs56219800, meta-analysis P=8.6x10
CONCLUSIONS: This work provides support for a polygenic architecture in D-TGA and identifies a susceptibility locus on chromosome 3p14.3 nea
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