Two-Phase Region of the Vortex-Solid Melting Transition: 3D XY Theory

In clean enough samples of the high-$T_c$ oxide materials, the phase transition into the superconducting state occurs along a first order line in the $H$-$T$ plane. This means that a two-phase region occurs in the B-$T$ plane, in which the liquid and solid vortex phases coexist. We discuss the thermodynamics of this two-phase region, developing formulae relating experimental quantities of interest. We then apply the 3D XY scaling theory to the problem, obtaining detailed predictions for the boundaries of the coexistence region. By using published data, we are able to predict the width of the two-phase region, and determine the physical parameters involved in the 3D XY description.Comment: 5 pages LaTeX, 1 .eps figure, uses epsf.st

Analysis of archaeological settlement patterns in Grasslands National Park, Saskatchewan

The purpose of this study is to analyze archaeological settlement patterns within Grass­lands National Park using Geographic Information Systems. Grasslands National Park is located in southwestern Saskatchewan along the international border and is split into West and East Blocks. The Park is primarily short grass prairie with the Frenchman River Valley running through the West Block and a system of north-south drainages running through the largely flatter grasslands of the East Block. Archaeological data for this study are derived from the results of an extensive survey of Grasslands National Park which recorded over 3000 surface sites. In addition to the survey, digital environmental data on topography, vegetation and soils were obtained from the Park for the purposes of analysis. Remote sensing data were used to conduct additional mapping of water sources. Analysis consisted of a statistical comparison of site and feature type distributions over classes of environmental data. Statistically significant results were interpreted within the frame­work of the archaeological context of southwestern Saskatchewan. The study found that specific feature types had particular relationships to topography and the environment. Sites with stone rings were often located in upland areas near seasonal water sources. An association between sites with stone rings and grasses which are preferred by bison for forage is particularly strong. As bison may have intensively occupied the Park area in the late spring to take advantage of late spring growth of some grasses, the Park may have been extensive­ly used by people hunting bison in the spring and early summer. In general topography, distance from water, and vegetation type were all significant factors in the distribution of sites and feature types. It is hoped that this thesis has provided a case study for the use of Geographic Information Systems within the archaeology of the Northern Plains. The large body of survey data along with access to numerous environmental data sets has provided an excellent opportunity to analyse settlement patterns within the Canadian plains

Creative Expression in Sculpture and Ceramic Forms

The purpose of this study was to explore the effects of metallic oxides and the process of wax resist in ceramic decoration; and the relationship of space and mass in sculpture. / The clay used for the ceramic problems was a stoneware body, except for the clay sculpture which was cast form a low fire slip. Metallic oxides were applied as stains during the green ware stage. Following the bisque firing, the ceramic pieces were glazed with a mixture of Horton’s and Matt # 3 glazes. / The use of wax resist, as a ceramic decoration, produced some very interesting results; many of which resemble those achieved in the field of graphics. To achieve these results, the design was first painted onto the clay with liquid wax. When the wax had set up, attain was applied to the entire outside surface. In the case of the vase pictured at the back of this abstract, a second application of wax was applied, covering both the first coat of wax and stain. Through this second application of wax, added design was incised into the clay and stained with another color. During the bisque firing the wax was burned out, preparing the piece for glazing. The possibilities of this method of decoration are by no means limited, and the freedom which the technique demands makes wax resist all the more fascinating. / The woods chosen for the wood sculpture are walnut and Osage orange (hedge). These were chosen for their hardness and active grain. On the walnut forms, spackle was applied to the entire surface as a filler. After sanding, a fruit wood stain was used to retain the natural color of the walnut wood. The final finish applied to all the wood sculpture was a mixture of bees wax and turpentine. / The form “Granted Petition” was the first of the wood pieces to be completed. The center of this particular piece of material was rotten and partially hollowed out; consequently, to achieve a satisfactory form, the lement of space was given a prominent role. The use of space and its relationship to mass in this form, gave new insight into the expressive quality of space. It took on not only definite shape and content, but made the form more a part of earth and light and expressive of life. Space was treated as being integral and equally as important as line, color, form and texture. / The writer in no way claims to have exhausted the possibilities of wax resist, but does feel that he has found the most gratifying technique of ceramic decoration for expressing himself in that material. With a greater use of space in sculpture, there was has been experienced a deeper appreciation for the element’s sculptural quality, and its potentiality for the expression of content

Conscientious Women: The Dispositional Conditions of Institutional Treatment on Civic Involvement

Current thinking about the effect of religion on civic engagement centers on “institutional treatment”—the development of resources, social pathways to recruitment, and motivation that occurs in small groups and activities of congregations. None of this work has yet incorporated the personality traits that may shape the uptake of institutional treatment. Following a growing line of research articulating how individual predispositions condition political involvement, we argue that gendered personality differences may moderate civic skill development. With new data, we find that women do not develop skills from religious involvement at the same rate as men and that this pattern is largely attributable to their distinctive personality profile. The results shift the balance between individuals and institutional influences by augmenting the cognitive bases for acquiring church-gained experiences and linking them to the public square

Global experts are more likely to be worried about electoral violence in the presidential election than their US counterparts.

Ahead of the US presidential election there is growing concern both at home and abroad about the health of American democracy. In a new study, Ilana Rothkopf, Paul Friesen, Luis Schenoni, Maggie Shum, and Romelia M. Solano asked 150 election experts from around the world about election scenarios. They found that experts outside the US were more concerned than their American counterparts about threats to US democracy such as violence at polling places, or other forms of voter intimidation

Valley splitting in strained silicon quantum wells

A theory based on localized-orbital approaches is developed to describe the valley splitting observed in silicon quantum wells. The theory is appropriate in the limit of low electron density and relevant for proposed quantum computing architectures. The valley splitting is computed for realistic devices using the quantitative nanoelectronic modeling tool NEMO. A simple, analytically solvable tight-binding model is developed, it yields much physical insight, and it reproduces the behavior of the splitting in the NEMO results. The splitting is in general nonzero even in the absence of electric field in contrast to previous works. The splitting in a square well oscillates as a function of S, the number of layers in the quantum well, with a period that is determined by the location of the valley minimum in the Brillouin zone. The envelope of the splitting decays as $S^3$. Finally the feasibility of observing such oscillations experimentally in modern Si/SiGe heterostructures is discussed.Comment: 19 pages, including 4 figure

Intrasubband and Intersubband Electron Relaxation in Semiconductor Quantum Wire Structures

We calculate the intersubband and intrasubband many-body inelastic Coulomb scattering rates due to electron-electron interaction in two-subband semiconductor quantum wire structures. We analyze our relaxation rates in terms of contributions from inter- and intrasubband charge-density excitations separately. We show that the intersubband (intrasubband) charge-density excitations are primarily responsible for intersubband (intrasubband) inelastic scattering. We identify the contributions to the inelastic scattering rate coming from the emission of the single-particle and the collective excitations individually. We obtain the lifetime of hot electrons injected in each subband as a function of the total charge density in the wire.Comment: Submitted to PRB. 20 pages, Latex file, and 7 postscript files with Figure

3D XY scaling theory of the superconducting phase transition

The intermediate 3D XY scaling theory of superconductivity at zero and nonzero magnetic fields is developed, based only upon the dimensional hypothesis $B\sim (Length)^{-2}$. Universal as well as nonuniversal aspects of the theory are identified, including background terms and demagnetization effects. Two scaling regions are predicted: an "inner" region (very near the zero field superconducting transition, $T_c$), where the fields $B$, $H$, and $H_{ex}$ differ substantially, due to the presence of diamagnetic fluctuations, and an "outer" region (away from $T_c$), where the fields can all be treated similarly. The characteristic field ($H_0$) and temperature ($t_1$) scales, separating the two regimes, are estimated. Scaling theories of the phase transition line, magnetization, specific heat, and conductivity are discussed. Multicritical behavior, involving critical glass fluctuations, is investigated along the transition line, $T_m(B)$, at nonzero fields.Comment: 9 pages LaTeX, 1 .eps figure, version accepted for publicatio