2,568 research outputs found
The Healing Bird
The legend of the caladrius, a bird with prognostic and healing powers, first appeared in early Indian writings as the haridruva - a yellow bird that cured jaundice. In classical Greek mythology it was a nondescript bird but in the medieval bestiaries it became pure white. The caladrius is used in the coats of arms of the South African Medical and Dental Council and also the Medical University of Soufhern Africa. These appear to be the first use of this medically significant bird in modern heraldry
Symmetrized mean-field description of magnetic instabilities in k-(BEDT-TTF)_2Cu[N(CN)]_2 Y salts
We present a novel and convenient mean-field method, and apply it to study
the metallic/antiferromagnetic interface of k-(BEDT-TTF)_2Cu[N(CN)]_2 Y organic
superconductors (BEDT_TTF is bis-ethylen-dithio-tetrathiafulvalene, Y=Cl, Br).
The method, which fully exploits the crystal symmetry, allows one to obtain the
mean-field solution of the 2D Hubbard model for very large lattices, up to
6x10^5 sites, yielding a reliable description of the phase boundary in a wide
region of the parameter space. The metal/antiferromagnet transtion appears to
be second order, except for a narrow region of the parameter space, where the
transition is very sharp and possibly first order. The cohexistence of metallic
and antiferromagnetic properties is only observed for the transient state in
the case of smooth second order transitions. The relevance of the present
resaults to the complex experimental behavior of centrosymmetric k-phase
BEDT-TTF salts is discussed.Comment: 9 pages in PS format, 7 figures (included in PS), 1 tabl
Courtship Behavior and Detection of Female Receptivity in the Parasitoid Wasp Urolepis rufipes
Once a Urolepis rufipes male mounted, the female beat her antennae against his mouth and clypeus. Immediately after he swept his antennae rapidly downward and extruded his mouthparts, her abdomen rose as she opened her genital orifice. Almost simultaneously he backed up for copulation and she folded her antennae against her head. Neither her abdomen rising nor her antennal folding were essential to his backing up as determined from their timing and from experiments in which her abdomen was sealed or her antennae were removed. Females did not open their genital orifice if with a sealed-mouth male; and antennae-removed females did not open even in the few cases where untreated males extruded their mouthparts. Unlike a closely related species, females mounted by sealed-mouth males did not open in response to air from containers of mating pairs.This article is made openly accessible in part by an award from the Northern Illinois University Libraries’ Open Access Publishing Fund
On the origin and application of the Bruggeman Correlation for analysing transport phenomena in electrochemical systems
The widely used Bruggeman equations correlate tortuosity factors of porous media with their porosity. Finding diverse application from optics to bubble formation, it received considerable attention in fuel cell and battery research, recently. The ability to estimate tortuous mass transport resistance based on porosity alone is attractive, because direct access to the tortuosity factors is notoriously difficult. The correlation, however, has limitations, which are not widely appreciated owing to the limited accessibility of the original manuscript. We retrace Bruggemans derivation, together with its initial assumptions, and comment on validity and limitations apparent from the original work to offer some guidance on its use.<br/
Symposium on Event Predictive Cognition
This symposium on Event-Predictive Cognition (EPCog) will scrutinize the apparent strong linkage between events and predictions. Events, characterized as “a segment of time at a given location that is conceived by an observer to have a beginning and an end” (p.3, Zacks & Tversky, 2001), seem to be predictively encoded in our minds, linking and temporarily binding the essential aspects that constitute an event. However, in different disciplines the concept of an event as well as of predictions and predictive encodings has been treated from different perspectives and by means of different paradigms
Carrier concentrations in Bi_{2}Sr_{2-z}La_{z}CuO_{6+\delta} single crystals and their relation to Hall coefficient and thermopower
We measured the thermopower S and the Hall coefficients R_H of
Bi_{2}Sr_{2-z}La_{z}CuO_{6+\delta} (BSLCO) single crystals in a wide doping
range, in an effort to identify the actual hole concentrations per Cu, p, in
this system. It is found that the "universal" relation between the
room-temperature thermopower and T_c does not hold in the BSLCO system.
Instead, comparison of the temperature-dependent R_H data with other cuprate
systems is used as a tool to identify the actual p value. To justify this
approach, we compare normalized R_H(T) data of BSLCO, La_{2-x}Sr_{x}CuO_{4}
(LSCO), YBa_{2}Cu_{3}O_{y}, and Tl_{2}Ba_{2}CuO_{6+\delta}, and demonstrate
that the R_H(T) data of the LSCO system can be used as a template for the
estimation of p. The resulting phase diagram of p vs T_c for BSLCO suggests
that T_c is anomalously suppressed in the underdoped samples, becoming zero at
around p ~ 0.10, while the optimum T_c is achieved at p ~ 0.16 as expected.Comment: 4 pages including 5 figures, accepted for publication in Phys. Rev.
B, Rapid Communication
The Doping Phase Diagram of Y1-xcaxba2(Cu1-yzny)3O7-d from Transport Measurements: Tracking the Pseudogap Below Tc (y = 0)
The effects of planar hole concentration, p, on the resistivity, r(T), of
sintered Y1-xCaxBa2(Cu1-yZny)3O7-d samples were investigated over a wide range
of Ca, Zn, and oxygen contents. Zn was used to suppress superconductivity and
this enabled us to extract the characteristic pseudogap temperature, T*(p),
from r(T,p) data below Tco(p) [ = Tc (y = 0)]. We have also located the
characteristic temperature, Tscf, marking the onset of significant
superconducting fluctuations above Tc, from the analysis of r(T,H,p) and r(T,p)
data. This enabled us to identify T*(p) near the optimum doping level where the
values of T*(p) and Tscf(p) are very close and hard to distinguish. We again
found that T*(p) depends only on the hole concentration p, and not on the level
of disorder associated with Zn or Ca substitutions. We conclude that (i) T*(p)
(and therefore, the pseudogap) persists below Tco(p) on the overdoped side and
does not merge with the Tco(p) line and (ii) T*(p), and thus the pseudogap
energy, extrapolates to zero at the doping p = 0.19 +/- 0.01.
PACS numbers: 74.25.Dw, 74.25. 74.62.Dh, 74.72.-h Key words: Pseudoap,
Superconducting fluctuationsComment: 14 pages (Text), 7 figure
Influence of grain-refiner addition on the morphology of fe-bearing intermetallics in a semi-solid processed Al-Mg-Si alloy
© The Minerals, Metals & Materials Society and ASM International 2013The three-dimensional morphologies of the Fe-bearing intermetallics in a semisolid-processed Al-Mg-Si alloy were examined after extracting the intermetallics. α -AlFeSi and β-AlFeSi are the major Fe-bearing intermetallics. Addition of Al-Ti-B grain refiner typically promotes β-AlFeSi formation. β-AlFeSi was observed with a flat, plate-like morphology with angular edges in the alloy with and without grain refiner, whereas α -AlFeSi was observed as "flower"-like morphology in the alloy with grain refiner. © 2013 The Minerals, Metals & Materials Society and ASM International
Magneto-Transport Properties of Doped RuSrGdCuO
RuSrGdCuO, in which magnetic order and superconductivity coexist
with , is a complex material which poses new and
important questions to our understanding of the interplay between magnetic and
superconducting (SC) order. Resistivity, Hall effect and thermopower
measurements on sintered ceramic RuSrGdCuO are presented, together
with results on a broad range of substituted analogues. The Hall effect and
thermopower both show anomalous decreases below which may be
explained within a simple two-band model by a transition from localized to more
itinerant behavior in the RuO layer at .Comment: 10 pages, 7 figures, submitted to Phys. Rev. B., correspondence to
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