151 research outputs found
PSS25 Mapping from visual acuity to utility in patients with macular oedema due to central retinal vein occlusion using data from the LEAVO trial
Intravitreal therapy with ranibizumab vs aflibercept vs bevacizumab for macular oedema due to central retinal vein occlusion : a within trial cost-utility analysis
Gaps and excitations in fullerides with partially filled bands : NMR study of Na2C60 and K4C60
We present an NMR study of Na2C60 and K4C60, two compounds that are related
by electron-hole symmetry in the C60 triply degenerate conduction band. In both
systems, it is known that NMR spin-lattice relaxation rate (1/T1) measurements
detect a gap in the electronic structure, most likely related to
singlet-triplet excitations of the Jahn-Teller distorted (JTD) C60^{2-} or
C60^{4-}. However, the extended temperature range of the measurements presented
here (10 K to 700 K) allows to reveal deviations with respect to this general
trend, both at high and low temperatures. Above room temperature, 1/T1 deviates
from the activated law that one would expect from the presence of the gap and
saturates. In the same temperature range, a lowering of symmetry is detected in
Na2C60 by the appearance of quadrupole effects on the 23Na spectra. In K4C60,
modifications of the 13C spectra lineshapes also indicate a structural
modification. We discuss this high temperature deviation in terms of a coupling
between JTD and local symmetry. At low temperatures, 1/TT tends to a
constant value for Na2C60, both for 13C and 23Na NMR. This indicates a residual
metallic character, which emphasizes the proximity of metallic and insulting
behaviors in alkali fullerides.Comment: 12 pages, 13 figure
Dalitz plot analysis of D_s+ and D+ decay to pi+pi-pi+ using the K-matrix formalism
FOCUS results from Dalitz plot analysis of D_s+ and D+ to pi+pi-pi+ are
presented. The K-matrix formalism is applied to charm decays for the first time
to fully exploit the already existing knowledge coming from the light-meson
spectroscopy experiments. In particular all the measured dynamics of the S-wave
pipi scattering, characterized by broad/overlapping resonances and large
non-resonant background, can be properly included. This paper studies the
extent to which the K-matrix approach is able to reproduce the observed Dalitz
plot and thus help us to understand the underlying dynamics. The results are
discussed, along with their possible implications on the controversial nature
of the sigma meson.Comment: To be submitted to Phys.Lett.B A misprint corrected in formula
The Infrared Behaviour of the Pure Yang-Mills Green Functions
We review the infrared properties of the pure Yang-Mills correlators and
discuss recent results concerning the two classes of low-momentum solutions for
them reported in literature; i.e. decoupling and scaling solutions. We will
mainly focuss on the Landau gauge and pay special attention to the results
inferred from the analysis of the Dyson-Schwinger equations of the theory and
from "{\it quenched}" lattice QCD. The results obtained from properly
interplaying both approaches are strongly emphasized.Comment: Final version to be published in FBS (54 pgs., 11 figs., 4 tabs
Catalysis of Dynamical Flavor Symmetry Breaking by a Magnetic Field in Dimensions
It is shown that in dimensions, a constant magnetic field is a strong
catalyst of dynamical flavor symmetry breaking, leading to generating a fermion
dynamical mass even at the weakest attractive interaction between fermions. The
effect is illustrated in the Nambu-Jona-Lasinio model in a magnetic field. The
low-energy effective action in this model is derived and the thermodynamic
properties of the model are established. The relevance of this effect for
planar condensed matter systems is pointed out.Comment: 11 pages, LaTeX. The final version (with minor corrections) which
appeared in Phys.Rev.Lett. 73 (1994) 349
Psychosocial Treatment of Children in Foster Care: A Review
A substantial number of children in foster care exhibit psychiatric difficulties. Recent epidemiologi-cal and historical trends in foster care, clinical findings about the adjustment of children in foster care, and adult outcomes are reviewed, followed by a description of current approaches to treatment and extant empirical support. Available interventions for these children can be categorized as either symptom-focused or systemic, with empirical support for specific methods ranging from scant to substantial. Even with treatment, behavioral and emotional problems often persist into adulthood, resulting in poor functional outcomes. We suggest that self-regulation may be an important mediat-ing factor in the appearance of emotional and behavioral disturbance in these children
Dalitz plot analysis of the D+ to K-pi+pi+ decay in the FOCUS experiment
Using data collected by the high energy photoproduction experiment FOCUS at
Fermilab we performed a Dalitz plot analysis of the Cabibbo favored decay D+ to
K-pi+ pi+. This study uses 53653 Dalitz-plot events with a signal fraction of ~
97%, and represents the highest statistics, most complete Dalitz plot analysis
for this channel. Results are presented and discussed using two different
formalisms. The first is a simple sum of Breit--Wigner functions with freely
fitted masses and widths. It is the model traditionally adopted and serves as
comparison with the already published analyses. The second uses a K-matrix
approach for the dominant S-wave, in which the parameters are fixed by first
fitting Kpi scattering data and continued to threshold by Chiral Perturbation
Theory. We show that the Dalitz plot distribution for this decay is consistent
with the assumption of two body dominance of the final state interactions and
the description of these interactions is in agreement with other data on the
Kpi final state.Comment: 21 pages, 10 figures, to be submitted to Phys.Lett.
Composição e estrutura arbórea em floresta estacional semidecidual no Espinhaço Meridional (Serra do Cipó, MG)
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