185 research outputs found
One-way electromagnetic Tamm states in magnetophotonic structures
We study surface Tamm states in magnetophotonic structures magnetized in the Cotton–Mouton (Voigt) geometry. We demonstrate that the periodicity violation due to the structure truncation together with the violation of the time reversal symmetry due to the presence of magneto-optical materials gives rise to nonreciprocality of the surface modes. Dispersion of forward and backward modes splits and becomes magnetization dependent. This results in the magnetization-induced transitions between bulk and surface modes and unidirectional propagation of surface waves.We thank the Australian Research Council for a financial
support and S. Fan for useful discussions. This work was
supported in part by the Super Optical Information Memory
Project from the Ministry of Education, Culture, Sports, Science
and Technology of Japan MEXT, and Grant-in-Aid
for Scientific Research S Grant No. 17106004 from Japan
Society for the Promotion of Science JSPS
The Method of a Two-Point Conditional Column Density for Estimating the Fractal Dimension of the Galaxy Distribution
We suggest a new method for estimating the fractal dimension of the spatial
distribution of galaxies, the method of selected cylinders. We show the
capabilities of this method by constructing a two-point conditional column
density for galaxies with known redshifts from the LEDA database. The fractal
dimension of a sample of LEDA and EDR SDSS galaxies has been estimated to be D
= 2.1 for cylinder lengths of 200 Mpc. Amajor advantage of the suggested method
is that it allows scales comparable to the catalog depth to be analyzed for
galaxy surveys in the form of conical sectors and small fields in the sky.Comment: 9 pages, 8 figure
Classical Cosmological Tests for Galaxies of the Hubble Ultra Deep Field
Images of the Hubble Ultra Deep Field are analyzed to obtain a catalog of
galaxies for which the angular sizes, surface brightness, photometric
redshifts, and absolute magnitudes are found. The catalog contains a total of
about 4000 galaxies identified at a high signal-to-noise ratio, which allows
the cosmological relations angular size{redshift and surface
brightness-redshift to be analyzed. The parameters of the evolution of linear
sizes and surface brightness of distant galaxies in the redshift interval
0.5-6.5 are estimated in terms of a grid of cosmological models with different
density parameters. The distribution of photometric redshifts of galaxies is
analyzed and possible superlarge inhomogeneities in the radial distribution of
galaxies are found with scale lengths as large as 2000 Mpc.Comment: 23 pages, 9 figures, 1 tabl
Production of heat-resistant EP220 and EP929 alloys by high-temperature treatment of melt
Analysis of samples of EP220 and EP929 alloys in the liquid and solid state permits the determination of the parameters for high-temperature melt treatment in their production. On heating to specific temperatures, the structure of the liquid alloys moves closer to equilibrium. In the solidification of such melt, the cast metal formed is characterized by finer grain structure, greater dispersity of the dendrites, and greater density and microhardness of the matrix. Industrial adoption of high-temperature melt treatment will improve plasticity, increase the long-term strength, and boost the product yield. The proposed technology does not fully utilize the potential of the alloy structure obtained after high-temperature melt treatment. The effect may be amplified by more prolonged holding of the melt at 1650°C and by optimization of the vacuum-arc heating, deformation, and heat treatment, in the light of the structural changes in the experimental samples of solid metal. © 2013 Allerton Press, Inc
Conceptual Problems of Fractal Cosmology
This report continues recent Peebles-Turner debate "Is cosmology solved?" and
considers the first results for Sandage's program for "Practical cosmology". A
review of conceptual problems of modern cosmological models is given, among
them: the nature of the space expansion; recession velocities of distant
galaxies more than velocity of light; cosmological Friedmann force; continuous
creation of gravitating mass in Friedmann's equation; cosmological pressure is
not able to produce a work; cosmological gravitational frequency shift;
Friedmann-Holtsmark paradox; the problem of the cosmological constant;
Einstein's and Mandelbrot's Cosmological Principles; fractality of observed
galaxy distribution; Sandage's 21st problem: Hubble - de Vaucouleurs paradox;
quantum nature of gravity force.Comment: 17 pages, no Figures, report presented at Gamow Memorial Conference,
August 1999, St.-Petersburg, Russi
Comparing the performance of 850 GHz integrated bias-tee superconductor-insulator-superconductor (SIS) mixers with single- and parallel-junction tuner
We present and compare the design and performance of two 850 GHz radial probe fed superconductor-insulator-superconductor mixers, where the antenna is aligned perpendicular to the E-Plane of the input full-height rectangular waveguide connected to a multiple flare-angles smooth-walled horn. Both designs are comprised of 0.5 µm2 hybrid niobium/aluminium-nitride/niobium-nitride tunnel junction, fabricated on top of a niobium titanium nitride ground plane with an Al wiring layer. The entire superconducting circuit is supported with a 40 µm thick quartz substrate. The major difference between the two designs is the method used to cancel out the parasitic junction capacitance for broadband performance. The first design utilises two identical junctions connected in parallel with a short transmission line to convert the capacitance of one junction into the equivalent inductance of the other junction, commonly known as the twin-junction tuning scheme; whilst the second design employs an end-loaded scheme with only one tunnel junction. We found that both methods offer similar radio frequency performances, with close to 2× the double sideband quantum noise temperature, but the twin-junction design is more resilient to fabrication tolerances. However, the end-loaded design offers a much better intermediate frequency (IF) bandwidth performance, made possible by the sub-micron and high current density tunnel junction technology. The improved IF performance is important for many millimetre (mm) and sub-mm observatories, such as future upgrades of Atacama Large Millimetre/sub-mm Array receivers, as well as forthcoming space-borne far-infrared missions. Therefore, we conclude that the single-junction mixer design is the preferred option for THz applications, as long as the fabrication error can be minimised within a certain limit
Computational structural and functional proteomics 235 IDENTIFICATION AND STRUCTURE-FUNCTIONAL ANALYSIS OF THE SPECIFICITY DETERMINING RESIDUES OF THE ALPHA SUBUNITS OF THE PROTEOSOMAL COMPLEX
SUMMARY Motivation: Proteosomes are polyenzymatic proteolytic structures that provide the degradation of the bulk of cytoplasmic proteins to oligopeptides. The proteosomal genes in the eukaryotes all arose by duplication of a single ancestral gene encoding the proteosomal subunits in the bacteria. The analysis of evolutionary events after duplication may be useful for discovering new information about proteosomal structural and functional properties. Results: We confine our study here to the detection of the positions of the α-subunits whose amino acid substitutions are specific to particular subunits of the proteosomal alpha-rings. We detected a set of the α-subunit positions whose substitutions are specific to the genes that encode the various proteosomal subunits. It was demonstrated that these specific amino acid substitutions are the features of residues that form the subunit contacts in the α-ring of the proteosomes. Availability: The proteosomal sequences, multiple sequence alignments and phylogenetic tree used in analysis are available upon request
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