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 4^4He 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$_3$ 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$_3$. 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/SrTiO3_3 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$_3$ 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

Observation-based trajectory of future sea level for the coastal United States tracks near high-end model projections

With its increasing record length and subsequent reduction in influence of shorter-term variability on measured trends, satellite altimeter measurements of sea level provide an opportunity to assess near-term sea level rise. Here, we use gridded measurements of sea level created from the network of satellite altimeters in tandem with tide gauge observations to produce observation-based trajectories of sea level rise along the coastlines of the United States from now until 2050. These trajectories are produced by extrapolating the altimeter-measured rate and acceleration from 1993 to 2020, with two separate approaches used to account for the potential impact of internal variability on the future estimates and associated ranges. The trajectories are used to generate estimates of sea level rise in 2050 and subsequent comparisons are made to model-based projections. It is found that observation-based trajectories of sea level from satellite altimetry are near or above the higher-end model projections contained in recent assessment reports, although ranges are still wide. &nbsp;</p

Detection of submicroscopic chromosomal abnormalities using microarray analysis:The value and pitfalls in prenatal and postnatal diagnosis

Chromosomal microarray enables identifying small genomic deletions and duplications that are not routinely seen on karyotyping. Microarray analysis therefore has emerged as a primary diagnostic tool for the evaluation of developmental delay and structural malformations in children in the Netherlands since 2008. When invasive prenatal diagnosis is indicated, because of ultrasound abnormalities and/or an increased risk for common aneuploidies (trisomy 21, 18 or 13) at first trimester screening, microarray analysis instead of conventional karyotyping will be applied when targeted molecular rapid aneuploidy detection reveals no abnormalities. Microarray analysis provides around 12-15% extra diagnosis in cases of mental retardation and/or structural abnormalities and it can provide 6% extra diagnosis in prenatal samples with a normal karyotype. Besides finding evident causative abnormalities, microarray analysis increases the detection rates of VOUS (variants of unknown significance) that, in particular during a pregnancy, induce emotional burden en counselling difficulties. Furthermore, CNVs that are pathogenic but not related with the phenotype (e.g. deletion of an oncogene) may complicate pretest and posttest counselling as well, since these findings may have health consequences for both patient and family members. Clinicians who request microarray analysis should be aware of these implications. In this paper, two prenatal and four postnatal case reports illustrate the ability to identify more clinically relevant abnormalities, but also limitations and coincidental findings in microarray analysis.</p

Probabilistic sea level projections at the coast by 2100

As sea level is rising along many low-lying and densely populated coastal areas, affected communities are investing resources to assess and manage future socio-economic and ecological risks created by current and future sea level rise. Despite significant progress in the scientific understanding of the physical mechanisms contributing to sea level change, projections beyond 2050 remain highly uncertain. Here, we present recent developments in the probabilistic projections of coastal mean sea level rise by 2100, which provides a summary assessment of the relevant uncertainties. Probabilistic projections can be used directly in some of the decision frameworks adopted by coastal engineers for infrastructure design and land use planning. However, relying on a single probability distribution or a set of distributions based upon a common set of assumptions can understate true uncertainty and potentially misinform users. Here, we put the probabilistic projections published over the last 5 years into context

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