16,609 research outputs found
Effects of street traffic noise in the night
The relationship between automobile traffic noise and the degree of disturbance experience experienced at night was explored through a random sample survey of 1600 individuals in rural and urban areas. The data obtained were used to establish threshold values
Medical Tourism in the Caribbean: A Call for Cooperation
Numerous Caribbean countries have discussed plans for developing medical tourism activities as a means of tourism diversification and economic development. These plans have been encouraged and shaped by outside agencies whose influence might cause a race-to-the-bottom environment between countries competing for the same niche of tourists. This paper provides a call for cooperation between local health officials in the Caribbean region to coordinate plans for the development of a medical tourism industry that enhances regional access to specialized healthcare and facilitates the movement of patients and healthcare resources throughout the region to enhance health equity and health outcomes in the Caribbean
Flight test and evaluation of Omega navigation in a general aviation aircraft. Volume 2: Appendices
Detailed documentation for each flight of the Omega Flight Evaluation study is presented, including flight test description sheets and actual flight data plots. Computer programs used for data processing and flight planning are explained and the data formats utilized by the Custom Interface Unit are summarized
A Four-Unit-Cell Periodic Pattern of Quasiparticle States Surrounding Vortex Cores in Bi2Sr2CaCu2O8+d
Scanning tunneling microscopy is used to image the additional quasiparticle
states generated by quantized vortices in the high-Tc superconductor
Bi2Sr2CaCu2O8+d. They exhibit a Cu-O bond oriented 'checkerboard' pattern, with
four unit cell (4a0) periodicity and a ~30 angstrom decay length. These
electronic modulations may be related to the magnetic field-induced, 8a0
periodic, spin density modulations of decay length ~70 angstroms recently
discovered in La1.84Sr0.16CuO4. The proposed explanation is a spin density wave
localized surrounding each vortex core. General theoretical principles predict
that, in the cuprates, a localized spin modulation of wavelength L should be
associated with a corresponding electronic modulation of wavelength L/2, in
good agreement with our observations.Comment: 10 pages, 3 figure
Reading instruction in first-grade classrooms: Do basals control teachers?
This study describes first-grade teachers beliefs and practices about reading instruction. Drawing from interview and observational data, 16 teachers from four districts were placed on a continuum from skills-based to literature-based in relationship to their use of the basal. Only 2 teachers were found to rely solely on the basal, while 3 teachers enhanced the basal with literature, and 4 teachers used only literature in their reading instruction. Six teachers enhanced their basal use with additional skills and 1 teacher relied on skills only in her reading instruction. This diversity\u27 of teaching beliefs and practices was corroborated by questionnaire data from a larger sample of teachers. Next, a framework developed by Belenky, Clinchy, Goldberger, and Tarule (1986) was used to categorize teachers\u27 ways of knowing. The findings showed 1 teacher to be a silent knower, 6 were received knowers, 1 was a subjective knower, 7 were procedural knowers, and 1 was a connected knower. Results challenge Shannon\u27s (1987) hypothesis that basals deskill teachers while supporting Sosniak and Stodolskv\u27s (1993) view that teachers are more autonomous in their use of textbook materials
Ginzburg-Landau Like Theory for High Temperature Superconductivity in the Cuprates: Emergent d-wave Order
High temperature superconductivity in the cuprates remains one of the most
widely investigated, constantly surprising, and poorly understood phenomena in
physics. Here, we describe briefly a new phenomenological theory inspired by
the celebrated description of superconductivity due to Ginzburg and Landau and
believed to describe its essence. This posits a free energy functional for the
superconductor in terms of a complex order parameter characterizing it. We
propose, for superconducting cuprates, a similar functional of the complex, in
plane, nearest neighbor spin singlet bond (or Cooper) pair amplitude psi_ij. A
crucial part of it is a (short range) positive interaction between nearest
neighbor bond pairs, of strength J'. Such an interaction leads to nonzero long
wavelength phase stiffness or superconductive long range order, with the
observed d-wave symmetry, below a temperature T_c\simzJ' where z is the number
of nearest neighbours; it is thus an emergent, collective consequence. Using
the functional, we calculate a large range of properties, e.g. the pseudogap
transition temperature T* as a function of hole doping x, the transition curve
T_c(x), the superfluid stiffness rho_s(x,T), the specific heat (without and
with a magnetic field) due to the fluctuating pair degrees of freedom, and the
zero temperature vortex structure. We find remarkable agreement with
experiment. We also calculate the self energy of electrons hopping on the
square cuprate lattice and coupled to electrons of nearly opposite momenta via
inevitable long wavelength Cooper pair fluctuations formed of these electrons.
The ensuing results for electron spectral density are successfully compared
with recent ARPES experiments, and comprehensively explain strange features
such as temperature dependent Fermi arcs above T_c and the 'bending' of the
superconducting gap below T_c .Comment: 22 pages, 14 figures, to appear in Int J Mod Phys
Josephson Coupling through a Quantum Dot
We derive, via fourth order perturbation theory, an expression for the
Josephson current through a gated interacting quantum dot. We analyze our
expression for two different models of the superconductor-dot-superconductor
(SDS) system. When the matrix elements connecting dot and leads are featureless
constants, we compute the Josephson coupling J_c as a function of the gate
voltage and Coulomb interaction. In the diffusive dot limit, we compute the
probability distribution P(J_c) of Josephson couplings. In both cases, pi
junction behavior (J_c < 0) is possible, and is not simply dependent on the
parity of the dot occupancy.Comment: 9 pages; 3 encapsulated PostScript figure
Highland Pond Utilization by Bats in the Ozark National Forest, Arkansas
During May through August 1996, wildlife ponds (man-made and/or naturally occurring) and road ruts on the Sylamore Ranger District, Ozark National Forest, Arkansas, were mist netted to determine extent of utilization by bats. Thirty-nine ponds and road ruts were netted one or more times during 53 nights. These water sources were originally constructed to support wildlife species such as deer, turkey, etc.. This study demonstrates that taxonomically and numerically diverse bat populations use these water sources. Seven hundred and seventy bats of nine species, including two endangered species, were netted. Bats were identified, and sex, reproductive status, forearm length, and weight were recorded. All bats were banded and released at the site of capture
Tailoring transport properties of phase-separated manganite films with ordered magnetic nanostructures
International audienceThe magnetotransport properties of thin manganite films (La 0.7 Ca 0.3 MnO 3) coupled with arrays of permalloy (Py) nanodots deposited on the surface of the film is studied as a function of temperature , magnetic field and size of the dots. In the presence of the magnetic dots, a reduction of the electrical resistivity is observed, especially at the insulator-to-metal transition, as well as a shift of the transition peak towards higher temperature. This indicates that, due to the local interface exchange coupling, highly conductive ferromagnetic domains are nucleated in the manganite film underneath the Py nanodots. The use of a simplified resistor network model allows us to estimate the size of the metallic regions induced by the exchange coupling. At low temperatures, these regions extend ∼ 70 nm beyond the edge of the nanodots, a lengthscale comparable to the correlation length of the ferromagnetic clusters in the phase-separated state of La 0.7 Ca 0.3 MnO 3
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