131 research outputs found
Stochastic theory of lineshape broadening in quasielastic He atom scattering with interacting adsorbates
The activated surface diffusion of interacting adsorbates is described in
terms of the so-called interacting single adsorbate approximation, which is
applied to the diffusion of Na atoms on Cu(001) for coverages up to 20% in
quasielastic He atom scattering experiments. This approximation essentially
consists of solving the standard Langevin equation with two noise sources and
frictions: a Gaussian white noise accounting for the friction with the
substrate, and a white shot noise characterized by a collisional friction
simulating the adsorbate-adsorbate collisions. The broadenings undergone by the
quasielastic peak are found to be in very good agreement with the experimental
data reported at two surface temperatures 200 and 300 K.Comment: 6 pages, 3 figure
Linear response theory of activated surface diffusion with interacting adsorbates
Activated surface diffusion with interacting adsorbates is analyzed within
the Linear Response Theory framework. The so-called interacting single
adsorbate model is justified by means of a two-bath model, where one harmonic
bath takes into account the interaction with the surface phonons, while the
other one describes the surface coverage, this leading to defining a
collisional friction. Here, the corresponding theory is applied to simple
systems, such as diffusion on flat surfaces and the frustrated translational
motion in a harmonic potential. Classical and quantum closed formulas are
obtained. Furthermore, a more realistic problem, such as atomic Na diffusion on
the corrugated Cu(001) surface, is presented and discussed within the classical
context as well as within the framework of Kramer's theory. Quantum corrections
to the classical results are also analyzed and discussed.Comment: 40 pages, 4 figure
Diagnóstico citológico de las recidivas tumorales de ameloblastoma: presentación de dos casos clínicos
Introducción: Los ameloblastomas son los tumores odontogénicos
más frecuentes del maxilar. A pesar de su aspecto citohistológico
de benignidad, se comportan como tumores invasivos,
recidivantes y con posibilidad de metastatizar.
La P.A.A.F. es una prueba rápida e incruenta que proporciona
un diagnóstico prequirúrgico evitando, en ocasiones, tomas
biópsicas destinadas al diagnóstico.
Presentamos las características citológicas de dos casos de
recidiva yugal de ameloblastoma de rama mandibular diagnosticados
por PAAF, así como su correlación citohistológica.
Casos clínicos: Dos pacientes, una mujer de 36 años y un varón
de 62 años, que acuden por tumoración mandibular de escasos
meses de evolución. En ambos casos, la primera aproximación
diagnóstica fue junto a los estudios radiológicos el estudio
histológico de la masa tumoral. Tras la extirpación terapeútica,
ambos casos recidivaron. El diagnóstico de las recidivas fue
establecido citológicamente mediante PAAF.
Las extensiones citológicas mostraron un fondo granular con
aislados macrófagos y células multinucleadas gigantes y una
abundante celularidad epitelial de aspecto basaloide dispuesta
en grupos cohesivos configurando imágenes de empalizada
periférica, así como pequeños grupos de células de metaplasia
escamosa.
Discusión: La PAAF se considera como un método diagnóstico rápido, incruento y fiable en el diagnóstico del ameloblastoma.
La citología de estos tumores revela los componentes de la lesión
que, en general, son suficientes para llegar al diagnóstico de
ameloblastoma, especialmente en casos de recidiva.Introduction: Ameloblastomas are the most frequent odontogenic
tumors of the maxilla. In spite of their benign cytohistological
appearance, they behave as invasive recurring tumors, with the
possibility of metastasis.
FNAB is a rapid, bloodless test that provides a pre-surgical
diagnosis, thus, on occasions avoiding the need for diagnostic
biopsies.
We present the cytological characteristics of two cases of jugal
recurrences of mandibular ameloblastomas diagnosed by FNAB,
as well as their cytohistological correlation.
Clinical cases: Two patients, a 36-year-old woman, and a 62-
year-old male who both attended with mandibular swelling
of a few months evolution. In both cases the first diagnostic
approximation was the histological study of the tumoral mass,
together with the radiological studies. Following therapeutic
extirpation both cases recurred. The diagnosis of the recurrences
was established cytologically by means of FNAB.
The cytologic smears revealed a granular background with isolated
macrophages and giant multinucleate cells and an abundant
epithelial cellularity of basaloid appearance arranged in cohesive
groups forming images of peripheral palidasing, as well as small
groups of squamous metaplastic cells.
Discussion: FNAB is considered to be a rapid, bloodless and reliable
method for the diagnosis of ameloblastoma. The cytology of these tumors reveals components of the lesion that, in general,
are sufficient for the diagnosis of ameloblastoma, especially in
cases of recurrence
Visual Field Progression in Glaucoma: Comparison Between PoPLR and ANSWERS
Purpose: It has been suggested that the detection of visual field progression can be improved by modeling statistical properties of the data such as the increasing retest variability and the spatial correlation among visual field locations. We compared a method that models those properties, Analysis with Non-Stationary Weibull Error Regression and Spatial Enhancement (ANSWERS), against a simpler one that does not, Permutation of Pointwise Linear Regression (PoPLR). Methods: Visual field series from three independent longitudinal studies in patients with glaucoma were used to compare the positive rate of PoPLR and ANSWERS. To estimate the false-positive rate, the same visual field series were randomly re-ordered in time. The first dataset consisted of series of 7 visual fields from 101 eyes, the second consisted of series of 9 visual fields from 150 eyes, and the third consisted of series of more than 9 visual fields (17.5 on average) from 139 eyes. Results: For a statistical significance of 0.05, the false-positive rates for ANSWERS were about 3 times greater than expected at 15%, 17%, and 16%, respectively, whereas for PoPLR they were 7%, 3%, and 6%. After equating the specificities at 0.05 for both models, positive rates for ANSWERS were 16%, 25%, and 38%, whereas for PoPLR they were 12%, 33%, and 49%, or about 5% greater on average (95% confidence interval = -1% to 11%). Conclusions: Despite being simpler and less computationally demanding, PoPLR was at least as sensitive to deterioration as ANSWERS once the specificities were equated. Translational Relevance: Close control of false-positive rates is key when visual fields of patients are analyzed for change in both clinical practice and clinical trials
La boda de los muertos : tragedia murciana en un acto y dos cuadros
Estrenada con éxito en el Teatro Ortiz de Murcia la noche del 14 de marzo de 192
Outcomes of gonioscopy-assisted transluminal trabeculotomy in pseudoexfoliative glaucoma: 24-month follow-up
AimTo report on outcomes of gonioscopy-assisted transluminal trabeculotomy (GATT) in eyes with pseudoexfoliative glaucoma (PXG).MethodsProspective, interventional, non-comparative case series. A total of 103 eyes from 84 patients with PXG were enrolled to undergo a 360-degree ab interno trabeculotomy with gonioscopic assistance using either a 5.0 polypropylene suture or an illuminated microcatheter with up to 24 months of follow-up. Main outcome measures were intraocular pressure (IOP), number of antiglaucoma medications, success rate (IOP reduction ≥20% from baseline or IOP between 6 and 21 mm Hg, without further glaucoma surgery) and complication rate.ResultsMean preoperative IOP was 27.1 mm Hg (95% CI 25.5 to 28.7) using 2.9 (SD 1.1) glaucoma medications which decreased postoperatively to 13.0 mm Hg (95% CI 11.5 to 14.4) and 1.0 (SD 1.1) medications at 24 months (p<0.001). Success rate was 89.2% at 24 months of follow-up, and complication rate was 2.9%.ConclusionAt 24 months of follow-up, our results for GATT in PXG demonstrate that this conjunctival sparing procedure effectively lowers IOP and reduces the medications with a low complication rate, in this relatively aggressive glaucoma subtype.</jats:sec
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