7,727 research outputs found
Nodal involvement evaluation in advanced cervical cancer: a single institutional experience
Purpose: To assess the usefulness of different imaging techniques in the detection of nodal involvement in patients with advanced
cervical carcinoma. Moreover, to analyze the correlation between the presurgical (FIGO) and postsurgical (pTNM) staging classifications.
Materials and Methods: All patients diagnosed with advanced cervical cancer (FIGO Stages IIB-IV) from 2005 to 2012 were
selected. The medical charts of 51 patients that underwent presurgical assessment with posterior surgical staging by means of paraaortic
lymphadenectomy, were reviewed. Nodal status assessment by computed tomography scan (CT scan), magnetic resonance
imaging (MRI), positron emission tomography (PET), and sonography was compared, as well as the size given in imaging techniques
compared to the final pathologic report information. Results: Presurgical analysis by CT scan, MRI, PET, and sonography showed
pelvic nodal involvement in 51.3% of patients, and para-aortic involvement in 30.8% of cases. CT scan showed positive pelvic nodes
in 35% of cases, but pathologic confirmation was observed in just 17.6% of cases. However, MRI resulted in higher rates of up to
48.8% of cases. Concerning para-aortic nodal involvement, CT scan showed positive nodes in 25% of cases, MRI in 3.2% of cases,
and the pathologic report in 15.6% of cases. The authors found significant differences between staging groups among both classifications
(FIGO vs. pTNM; p < 0.001). Eight cases (15.7%) were understaged by FIGO classification. Conclusions: Despite all imaging
techniques available, none has demonstrated to be efficient enough to avoid the systematic study of para-aortic nodal status by
means of surgical evaluatio
Evidence of non-thermal X-ray emission from HH 80
Protostellar jets appear at all stages of star formation when the accretion
process is still at work. Jets travel at velocities of hundreds of km/s,
creating strong shocks when interacting with interstellar medium. Several cases
of jets have been detected in X-rays, typically showing soft emission. For the
first time, we report evidence of hard X-ray emission possibly related to
non-thermal processes not explained by previous models of the post-shock
emission predicted in the jet/ambient interaction scenario. HH 80 is located at
the south head of the jet associated to the massive protostar IRAS 18162-2048.
It shows soft and hard X-ray emission in regions that are spatially separated,
with the soft X-ray emission region situated behind the region of hard X-ray
emission. We propose a scenario for HH 80 where soft X-ray emission is
associated to thermal processes from the interaction of the jet with denser
ambient matter and the hard X-ray emission is produced by synchrotron radiation
at the front shock.Comment: Accepted for publication in ApJ
Turbulence Time Series Data Hole Filling using Karhunen-Loeve and ARIMA methods
Measurements of optical turbulence time series data using unattended
instruments over long time intervals inevitably lead to data drop-outs or
degraded signals. We present a comparison of methods using both Principal
Component Analysis, which is also known as the Karhunen--Loeve decomposition,
and ARIMA that seek to correct for these event-induced and mechanically-induced
signal drop-outs and degradations. We report on the quality of the correction
by examining the Intrinsic Mode Functions generated by Empirical Mode
Decomposition. The data studied are optical turbulence parameter time series
from a commercial long path length optical anemometer/scintillometer, measured
over several hundred metres in outdoor environments.Comment: 8 pages, 9 figures, submitted to ICOLAD 2007, City University,
London, U
Evaluación de las condiciones de mezcla y su influencia sobre el cloro residual entanques de compensación de un sistema de distribución de agua potable
We performed a real scale evaluation of mixing conditions and its influence on water quality in a compensation tank of drinking-water distribution system located in the city of Cali, Colombia. The hydrodynamic study with continuous injection of tracer, and temperature and free chlorine measurements for identifying the mixing regime in the tank’s interior, residence time, thermal stratification, and chlorine variations in the stored water showed the typical characteristics of a compensation tank. We concluded that water recirculation, inadequate water exchange, low moment fluxes associated with low velocity flows, and punctual thermal stratification could lead to high water age, high residence times in the tank, inadequate mixing, and important loss of free residual chlorine. The methodology developed is suitable for evaluation and optimization of compensation tanks of drinking water distribution systems.Realizamos una evaluación a escala real de las condiciones de mezcla y su influencia en la calidad del agua en un tanque de compensación del sistema de distribución de agua potable ubicado en la ciudad de Cali, Colombia. El estudio hidrodinámico con inyección continua de marcador y mediciones de temperatura y cloro libre para identificar el régimen de mezcla en el interior del tanque, el tiempo de residencia, la estratificación térmica y las variaciones de cloro en el agua almacenada mostraron las características típicas de un tanque de compensación. Llegamos a la conclusión de que la recirculación de agua, el intercambio de agua inadecuado, los flujos de momento bajos asociados con los flujos de baja velocidad y la estratificación térmica puntual podrían conducir a una alta edad del agua, tiempos de residencia elevados en el tanque, mezcla inadecuada y pérdida importante de cloro residual libre. La metodología desarrollada es adecuada para la evaluación y optimización de tanques de compensación de sistemas de distribución de agua potable
The role of temperature in the magnetic irreversibility of type-I Pb superconductors
Evidence of how temperature takes part in the magnetic irreversibility in the
intermediate state of a cylinder and various disks of pure type-I
superconducting lead is presented. Isothermal measurements of first
magnetization curves and magnetic hysteresis cycles are analyzed in a reduced
representation that defines an equilibrium state for flux penetration in all
the samples and reveals that flux expulsion depends on temperature in the disks
but not in the cylinder. The magnetic field at which irreversibility sets in
along the descending branch of the hysteresis cycle and the remnant
magnetization at zero field are found to decrease with temperature in the
disks. The contributions to irreversibility of the geometrical barrier and the
energy minima associated to stress defects that act as pinning centers on
normal-superconductor interfaces are discussed. The differences observed among
the disks are ascribed to the diverse nature of the stress defects in each
sample. The pinning barriers are suggested to decrease with the magnetic field
to account for these results
Expedições de coletas de feijão comum (Phaseolus vulgaris) no Brasil.
Objetivando a preservação da diversidade genética ainda existente entre os agricultores tradicionais de feijão comum, foram realizadas expedições de coleta na Região Norte do Rio Grande do Sul e nos Estados de Sergipe, Bahia e Ceará
Análise conjuntural da cultura do arroz nas regiões brasileiras.
O presente trabalho teve por objetivo analisar e demonstrar o movimento migratório da cultura do arroz em termos de área plantada e volume de produção nas regiões Norte, Nordeste, Centro-Oeste, Sudeste e Sul do Brasil nas safras de 1978/79, 1988/89, 1998/1999 e 2008/2009
Noncommutative spaces, the quantum of time and the Lorentz symmetry
We introduce three space-times that are discrete in time and compatible with
the Lorentz symmetry. We show that these spaces are no commutative, with
commutation relations similar to the relations of the Snyder and Yang spaces.
Furthermore, using a reparametrized relativistic particle we obtain a
realization of the Snyder type spaces and we construct an action for them.Comment: 8 pages, to appear in PR
The Universal Cut Function and Type II Metrics
In analogy with classical electromagnetic theory, where one determines the
total charge and both electric and magnetic multipole moments of a source from
certain surface integrals of the asymptotic (or far) fields, it has been known
for many years - from the work of Hermann Bondi - that energy and momentum of
gravitational sources could be determined by similar integrals of the
asymptotic Weyl tensor. Recently we observed that there were certain overlooked
structures, {defined at future null infinity,} that allowed one to determine
(or define) further properties of both electromagnetic and gravitating sources.
These structures, families of {complex} `slices' or `cuts' of Penrose's null
infinity, are referred to as Universal Cut Functions, (UCF). In particular, one
can define from these structures a (complex) center of mass (and center of
charge) and its equations of motion - with rather surprising consequences. It
appears as if these asymptotic structures contain in their imaginary part, a
well defined total spin-angular momentum of the source. We apply these ideas to
the type II algebraically special metrics, both twisting and twist-free.Comment: 32 page
Dynamic Approach to the Fully Frustrated XY Model
Using Monte Carlo simulations, we systematically investigate the
non-equilibrium dynamics of the chiral degree of freedom in the two-dimensional
fully frustrated XY model. The critical initial increase of the staggered
chiral magnetization is observed. By means of the short-time dynamics approach,
we estimate the second order phase transition temperature and all the
dynamic and static critical exponents , z, and .Comment: 5 pages with 6 figures include
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