3,019 research outputs found
Multitarget sequential sputtering apparatus
The development and characteristics of a sputtering apparatus are discussed. A potential difference is applied between the cathode and anode to produce a plasma for each target which is sputtered by accelerated ions within the plasma. The process of sputtering for various materials is described. Diagrams of the unit are provided
Association between generation gap in interest, familiarity and application of information and communication technology
Given the introduction of information and communication technology and its rapid progress in every society, its use and application is different between various social institutions in that it demonstrates the difference between previous and present generation. Hence, the research was conducted in the school year 2012-2013 with the aim of applying information technology among female high school students and their mothers in Gorgan Province. The research method is a descriptive-analytical method; using a cluster sampling, of 34 female schools 8 schools were randomly chosen and 260 students were included in the study out of 1625 students. Using collected questionnaires and information obtained from independent t-test the results indicated that there was a significant difference between the mean of familiarity, interest and mothers' and their children's use of information technology. © Medwell Journals, 2016
Monte-Carlo simulation study of the two-stage percolation transition in enhanced binary trees
We perform Monte-Carlo simulations to study the Bernoulli () bond
percolation on the enhanced binary tree which belongs to the class of
nonamenable graphs with one end. Our numerical results show that the system has
two different percolation thresholds and . All the points in
the intermediate phase are critical and there exist
infinitely many infinite clusters in the intermediate phase. In this phase the
corresponding fractal exponent continuously increases with from zero to
unity.Comment: 4 pages, 6 figure
Orienting coupled quantum rotors by ultrashort laser pulses
We point out that the non-adiabatic orientation of quantum rotors, produced
by ultrashort laser pulses, is remarkably enhanced by introducing dipolar
interaction between the rotors. This enhanced orientation of quantum rotors is
in contrast with the behavior of classical paired rotors, in which dipolar
interactions prevent the orientation of the rotors. We demonstrate also that a
specially designed sequence of pulses can most efficiently enhances the
orientation of quantum paired rotors.Comment: 7 pages, 5 figures, to appear in Phys. Rev.
Money and Goldstone modes
Why is ``worthless'' fiat money generally accepted as payment for goods and
services? In equilibrium theory, the value of money is generally not
determined: the number of equations is one less than the number of unknowns, so
only relative prices are determined. In the language of mathematics, the
equations are ``homogeneous of order one''. Using the language of physics, this
represents a continuous ``Goldstone'' symmetry. However, the continuous
symmetry is often broken by the dynamics of the system, thus fixing the value
of the otherwise undetermined variable. In economics, the value of money is a
strategic variable which each agent must determine at each transaction by
estimating the effect of future interactions with other agents. This idea is
illustrated by a simple network model of monopolistic vendors and buyers, with
bounded rationality. We submit that dynamical, spontaneous symmetry breaking is
the fundamental principle for fixing the value of money. Perhaps the continuous
symmetry representing the lack of restoring force is also the fundamental
reason for large fluctuations in stock markets.Comment: 7 pages, 3 figure
Flux-free conductance modulation in a helical Aharonov-Bohm interferometer
A novel conductance oscillation in a twisted quantum ring composed of a
helical atomic configuration is theoretically predicted. Internal torsion of
the ring is found to cause a quantum phase shift in the wavefunction that
describes the electron's motion along the ring. The resulting conductance
oscillation is free from magnetic flux penetrating inside the ring, which is in
complete contrast with the ordinary Aharonov-Bohm effect observed in untwisted
quantum rings.Comment: 10 pages, 4 figure
Diverse corrugation pattern in radially shrinking carbon nanotubes
Stable cross-sections of multi-walled carbon nanotubes subjected to
electron-beam irradiation are investigated in the realm of the continuum
mechanics approximation. The self-healing nature of sp graphitic sheets
implies that selective irradiation of the outermost walls causes their radial
shrinkage with the remaining inner walls undamaged. The shrinking walls exert
high pressure on the interior part of nanotubes, yielding a wide variety of
radial corrugation patterns ({\it i.e.,} circumferentially wrinkling
structures) in the cross section. All corrugation patterns can be classified
into two deformation phases for which the corrugation amplitudes of the
innermost wall differ significantly.Comment: 8 pages, 4 figure
Changes over time in the spatial distribution of walleye pollock (Theragra chalcogramma) in the Gulf of Alaska, 1984-1996
Triennial bottom trawl survey data from 1984 to 1996 were used to evaluate changes in the summer distribution of walleye pollock in the western and central Gulf of Alaska. Differences between several age groups of pollock were evaluated. Distribution was examined in relation to several physical characteristics, including bottom depth and distance from land. Interspecies associations were also analyzed with the Bray-Curtis clustering technique to better understand community structure. Our results indicated that although the population numbers decreased, high concentrations of pollock remained in the same areas during 1984–96. However, there was an increase in the number of stations where low-density pollock concentrations of all ages were observed, which resulted in a decrease in mean population density of pollock within the GOA region. Patterns emerging from our data suggested an alternative to Mac-Call’s “basin hypothesis” which states that as population numbers decrease, there should be a contraction of the population range to optimal habitats.
During 1984–96 there was a concurrent precipitous decline in Steller sea lions in the Gulf of Alaska. The results of our study suggest that decreases in the mean density of adult pollock, the main food in the Steller sea lion diet, combined with slight changes in the distribution of pollock (age-1 pollock in particular) in the mid-1980s, may have contributed to decreased foraging efficiency in Steller sea lions. Our results support the prevailing conceptual model for pollock ontogeny, although there is evidence that substantial spawning may also occur outside of Shelikof Strait
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