17,088 research outputs found
Raman scattering studies of temperature- and field-induced melting of charge order in (La,Pr,Ca)MnO
We present Raman scattering studies of the structural and magnetic phases
that accompany temperature- and field-dependent melting of charge- and
orbital-order (COO) in La0.5Ca0.5MnO3 and La0.25Pr0.375Ca0.375MnO3. Our results
show that thermal and field-induced COO melting in La0.5Ca0.5MnO3 exhibits
three stages in a heterogeneous melting process associated with a structural
change: a long-range, strongly JT distorted/COO regime; a coexistence regime;
and weakly JT distorted/PM or FM phase. We provide a complete structural phase
diagram of La0.5Ca0.5MnO3 for the temperature and field ranges 6<=T<=170 K and
0<=H<=9 T. We also investigate thermal and field-induced melting in
La0.25Pr0.375Ca0.375MnO3 to elucidate the role of disorder in melting of COO.
We find that while thermal melting of COO in La0.25Pr0.375Ca0.375MnO3 is quite
similar to that in La0.5Ca0.5MnO3, the field-induced transition from the COO
phase to the weakly JT-distorted/FM phase in La0.25Pr0.375Ca0.375MnO3 is very
abrupt, and occurs at significantly lower fields (H~2 T at T~0 K) than in
La0.5Ca0.5MnO3 (H~30 T at T=0 K). Moreover, the critical field H_c increases
with increasing temperature in La0.25Pr0.375Ca0.375MnO3 in contrast to
La0.5Ca0.5MnO3. To explain these differences, we propose that field-induced
melting of COO in La0.25Pr0.375Ca0.375MnO3 is best described as the
field-induced percolation of FM domains, and we suggest that Griffiths phase
physics may be an appropriate theoretical model for describing the unusual
temperature- and field- dependent transitions observed in
La0.25Pr0.375Ca0.375MnO3.Comment: 14 pages, 8 figures, to be published in PR
Quimioterapia das Tripanosomoses ocorrentes no Pantanal.
bitstream/CPAP/56590/1/DOC65.pdfFormato eletrônico
GRB 000911: Evidence for an Associated Supernova?
We present photometric and spectroscopic observations of the late afterglow of GRB 000911. We detect a moderately significant re-brightening in the R, I and J lightcurves, associated with a sizable reddening of the spectrum. This can be explained through the presence of an underlying supernova, outshining the afterglow ~ 30 days after the burst event
Correlated electron states and transport in triangular arrays
We study correlated electron states in frustrated geometry of a triangular
lattice. The interplay of long range interactions and finite residual entropy
of a classical system gives rise to unusual effects in equilibrium ordering as
well as in transport. A novel correlated fluid phase is identified in a wide
range of densities and temperatures above freezing into commensurate solid
phases. The charge dynamics in the correlated phase is described in terms of a
height field, its fluctuations, and topological defects. We demonstrate that
the height field fluctuations give rise to a ``free'' charge flow and finite dc
conductivity. We show that freezing into the solid phase, controlled by the
long range interactions, manifests itself in singularities of transport
properties.Comment: 19 pages, 10 figure
Public awareness of cancer in Britain: a population-based survey of adults
*_Objective:_* To assess public awareness of cancer warning signs, anticipated delay, and perceived barriers to seeking medical advice in the British population. 
Methods: We carried out a population-based survey using face-to-face, computer-assisted interviews to administer the Cancer Awareness Measure (CAM), a newly-developed, validated measure of cancer awareness. The sample included 2216 adults (970 male and 1246 female) recruited as part of the Office for National Statistics Opinions Survey using stratified probability sampling.

*_Results:_* Awareness of cancer warning signs was low when open-ended (recall) questions were used and higher with closed (recognition) questions; but on either measure, awareness was lower in those who were male, younger, and from lower socioeconomic status (SES) groups or ethnic minorities. The most commonly endorsed barriers to help-seeking were difficulty making an appointment, worry about wasting the doctor’s time and worry about what would be found. Emotional barriers were more prominent in lower SES groups and practical barriers (e.g. too busy) more prominent in higher SES groups. Anticipated delay was lower in ethnic minority and lower SES groups. In multivariate analysis, higher symptom awareness was associated with lower anticipated delay, and more barriers with greater anticipated delay.

*_Conclusions:_* A combination of public education about symptoms and empowerment to seek medical advice, as well as support at primary care level, could enhance early presentation and improve cancer outcomes
Phase transitions in the one-dimensional frustrated quantum XY model and Josephson-junction ladders
A one-dimensional quantum version of the frustrated XY (planar rotor) model
is considered which can be physically realized as a ladder of
Josephson-junctions at half a flux quantum per plaquette. This system undergoes
a superconductor to insulator transition at zero temperature as a function of
charging energy. The critical behavior is studied using a Monte Carlo transfer
matrix applied to the path-integral representation of the model and a
finite-size-scaling analysis of data on small system sizes. Depending on the
ratio between the interchain and intrachain couplings the system can have
single or double transitions which is consistent with the prediction that its
critical behavior should be described by the two-dimensional classical XY-Ising
model.Comment: 13 pages, Revtex, J. Appl. Phys. (to appear), Inpe-las-00
Profilaxia e controle do mal de cadeiras em animais domésticos no Pantanal.
O Trypanosoma evansi foi o primeiro tripanosoma patogênico descoberto. A surra, como a doença é conhecida na Índia, causada pelo T. evansi, há muitos séculos tem sido observada. Porém, foi somente em 1880 que Griffith Evans descobriu organismos móveis semelhantes a espirilos no sangue de cavalos e camelos doentes. Evans descreveu os parasitas em esfregaço frescos e os reconheceu como sendo protozoários. Evans acreditou que a fonte primária da infecção dos cavalos fossem as águas poluídas (Hoare, 1972).bitstream/item/81127/1/DOC66.pd
Shape of the Galactic Orbits in Clusters
A kinematical analysis applied to a sample of galaxy clusters indicates that
the differences between the velocity distribution of elliptical and spiral
galaxies are associated with the shape of their orbit families. The orbital
anisotropies present on each morphological population could be measured with
the use of a parameter which is the ratio of the radial and tangential velocity
dispersions, and can be recovered through the observed line-of-sight velocity
distribution. When a Gaussian velocity distribution is assumed, having
different dispersions along the radial and tangential directions, we conclude
that the orbits of elliptical galaxies in clusters are close to radial, while
spirals have more circular shaped or isotropic orbits. Lenticulars galaxies
shares an intermediate orbital parameter, between spirals and ellipticals.Comment: 23 pages including 6 EPS-figures, and 4 tables. Accepted for
publication by ApJ, April 199
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