71 research outputs found
Extracting respiratory signals from thoracic cone beam CT projections
Patient respiratory signal associated with the cone beam CT (CBCT)
projections is important for lung cancer radiotherapy. In contrast to
monitoring an external surrogate of respiration, such signal can be extracted
directly from the CBCT projections. In this paper, we propose a novel local
principle component analysis (LPCA) method to extract the respiratory signal by
distinguishing the respiration motion-induced content change from the gantry
rotation-induced content change in the CBCT projections. The LPCA method is
evaluated by comparing with three state-of-the-art projection-based methods,
namely, the Amsterdam Shroud (AS) method, the intensity analysis (IA) method,
and the Fourier-transform based phase analysis (FT-p) method. The clinical CBCT
projection data of eight patients, acquired under various clinical scenarios,
were used to investigate the performance of each method. We found that the
proposed LPCA method has demonstrated the best overall performance for cases
tested and thus is a promising technique for extracting respiratory signal. We
also identified the applicability of each existing method.Comment: 21 pages, 11 figures, submitted to Phys. Med. Bio
Physics-based Residual Kriging for dynamically evolving functional random fields
AbstractWe present a novel approach named Physics-based Residual Kriging for the statistical prediction of spatially dependent functional data. It incorporates a physical model—expressed by a partial differential equation—within a Universal Kriging setting through a geostatistical modelization of the residuals with respect to the physical model. The approach is extended to deal with sequential problems, where samples of functional data become available along consecutive time intervals, in a context where the physical and stochastic processes generating them evolve, as time intervals succeed one another. An incremental modeling is used to account for both these dynamics and the misfit between previous predictions and actual observations. We apply Physics-based Residual Kriging to forecast production rates of wells operating in a mature reservoir according to a given drilling schedule. We evaluate the predictive errors of the method in two different case studies. The first deals with a single-phase reservoir where production is supported by fluid injection, while the second considers again a single-phase reservoir but the production is driven by rock compaction
The stellar content of the super star clusters in NGC 1569
We discuss HST FOS ultraviolet spectroscopy and NICMOS near-infrared
photometry of four young super star clusters in the central region of the
irregular starburst galaxy NGC 1569. The new observations coupled with previous
HST WFPC2 photometry and ground-based optical spectroscopy allow us to isolate
and age-date the hot and cool stellar components of these massive clusters. We
analyze the two components A1 and A2 of the brightest super star cluster NGC
1569-A. This cluster received previous attention due to the simultaneous
presence of Wolf-Rayet stars and red supergiants. The FOS spectra provide the
first evidence for O-stars in NGC 1569-A, indicating a young (5 Myr) stellar
component in A1 and/or A2. Comparison with other high-mass star-forming regions
suggests that the O- and Wolf-Rayet stars are spatially coincident. If so,
cluster A2 could be the host of the very young O- and Wolf-Rayet population,
and the somewhat older red supergiants could be predominantly located in A1.
The mass-to-light ratio of NGC 1569-A1 is analyzed in five optical and infrared
photometric bands and compared to evolutionary synthesis models. No indications
for an anomalous initial mass function are found, consistent with a scenario
where this cluster is the progenitor of present-day globular clusters. The
clusters A1 and A2 are compared to clusters B and #30. The latter two clusters
are older and fully dominated by red supergiants. All four super star clusters
provide a significant fraction (20 - 25%) of the total optical and
near-infrared light in the central region of the galaxy. The photometric
properties of the super star cluster population in NGC 1569 resemble those of
the populous clusters in the Magellanic Clouds
New Hampshire Insurance Co. v. Ballard-Wade, Inc. et al : Brief of Respondent
Appeal from Judgment of the 3rd District Court for Salt Lake County. Hon. A. H. Ellett, Judge
CB1 Signaling in Forebrain and Sympathetic Neurons Is a Key Determinant of Endocannabinoid Actions on Energy Balance
SummaryThe endocannabinoid system (ECS) plays a critical role in obesity development. The pharmacological blockade of cannabinoid receptor type 1 (CB1) has been shown to reduce body weight and to alleviate obesity-related metabolic disorders. An unsolved question is at which anatomical level CB1 modulates energy balance and the mechanisms involved in its action. Here, we demonstrate that CB1 receptors expressed in forebrain and sympathetic neurons play a key role in the pathophysiological development of diet-induced obesity. Conditional mutant mice lacking CB1 expression in neurons known to control energy balance, but not in nonneuronal peripheral organs, displayed a lean phenotype and resistance to diet-induced obesity. This phenotype results from an increase in lipid oxidation and thermogenesis as a consequence of an enhanced sympathetic tone and a decrease in energy absorption. In conclusion, CB1 signaling in the forebrain and sympathetic neurons is a key determinant of the ECS control of energy balance
A comprehensive study on the relationship between image quality and imaging dose in low-dose cone beam CT
While compressed sensing (CS) based reconstructions have been developed for
low-dose CBCT, a clear understanding on the relationship between the image
quality and imaging dose at low dose levels is needed. In this paper, we
qualitatively investigate this subject in a comprehensive manner with extensive
experimental and simulation studies. The basic idea is to plot image quality
and imaging dose together as functions of number of projections and mAs per
projection over the whole clinically relevant range. A clear understanding on
the tradeoff between image quality and dose can be achieved and optimal
low-dose CBCT scan protocols can be developed for various imaging tasks in
IGRT. Main findings of this work include: 1) Under the CS framework, image
quality has little degradation over a large dose range, and the degradation
becomes evident when the dose < 100 total mAs. A dose < 40 total mAs leads to a
dramatic image degradation. Optimal low-dose CBCT scan protocols likely fall in
the dose range of 40-100 total mAs, depending on the specific IGRT
applications. 2) Among different scan protocols at a constant low-dose level,
the super sparse-view reconstruction with projection number less than 50 is the
most challenging case, even with strong regularization. Better image quality
can be acquired with other low mAs protocols. 3) The optimal scan protocol is
the combination of a medium number of projections and a medium level of
mAs/view. This is more evident when the dose is around 72.8 total mAs or below
and when the ROI is a low-contrast or high-resolution object. Based on our
results, the optimal number of projections is around 90 to 120. 4) The
clinically acceptable lowest dose level is task dependent. In our study,
72.8mAs is a safe dose level for visualizing low-contrast objects, while 12.2
total mAs is sufficient for detecting high-contrast objects of diameter greater
than 3 mm.Comment: 19 pages, 12 figures, submitted to Physics in Medicine and Biolog
Brain-derived neurotrophic factor (BDNF) expression in normal and regenerating olfactory epithelium of Xenopus laevis
Olfactory epithelium has the capability to continuously regenerate olfactory receptor neurons throughout life. Adult neurogenesis results from proliferation and differentiation of neural stem cells, and consequently, olfactory neuroepithelium offers an excellent opportunity to study neural regeneration and the factors involved in the maintenance and regeneration of all their cell types. We analyzed the expression of BDNF in the olfactory system under normal physiological conditions as well as during a massive regeneration induced by chemical destruction of the olfactory epithelium in Xenopus laevis larvae. We described the expression and presence of BDNF in the olfactory epithelium and bulb. In normal physiological conditions, sustentacular (glial) cells and a few scattered basal (stem) cells express BDNF in the olfactory epithelium as well as the granular cells in the olfactory bulb. Moreover, during massive regeneration, we demonstrated a drastic increase in basal cells expressing BDNF as well as an increase in BDNF in the olfactory bulb and nerve. Together these results suggest an important role of BDNF in the maintenance and regeneration of the olfactory system.Fil: Frontera, Jimena Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; ArgentinaFil: Cervino, Ailen Soledad. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental. Laboratorio de Biología del Desarrollo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Jungblut, Lucas David. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; ArgentinaFil: Paz, Dante Agustin. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; Argentin
El estado de las negociaciones comerciales internacionales : informe 1-2018
El Grupo de Estudios sobre Negociaciones Comerciales Internacionales, radicado en el
Instituto de Investigaciones de la Facultad de Ciencia Política y Relaciones
Internacionales de la Universidad Nacional de Rosario, tiene como meta analizar la
evolución de la gobernanza global del comercio mundial, considerando las dinámicas
de las negociaciones comerciales internacionales en el marco de la Organización
Mundial del Comercio, las negociaciones comerciales mega-regionales, y las
negociaciones comerciales de los países en desarrollo en el siglo XXI; se propone
asimismo difundir y fomentar los estudios sobre negociaciones comerciales
internacionales dentro del ámbito de la Facultad de Ciencia Política y Relaciones
Internacionales de la UNR; y promover capacidades analíticas en materia de
negociaciones comerciales internacionales y fomentar vocaciones científicas entre los
estudiantes y graduados de la Facultad de Ciencia Política y Relaciones Internacionales
de la UNR.
El presente informe es resultado del trabajo de alumnos, graduados y docentes de la
Facultad de Ciencia Política y Relaciones Internacionales, dedicados a tales cuestiones.
En las próximas páginas se realiza un seguimiento de los procesos de negociaciones
comerciales internacionales contemporáneos, ordenados por área geográfica.
El recorte temporal del informe corresponde a los meses de enero, febrero y marzo de
2018. En esta edición nos concentramos en el proceso que involucró la firma del
Tratado Integral y Progresista de Asociación Transpacífico, también conocido como
TPP-11 o CPTPP. Asimismo, incorporamos una nueva sección de comentarios de
coyuntura, y se ha modificado la sección de seguimiento de los procesos en cursos,
ahora con un diseño más compactoFil: Zelicovich, Julieta. Universidad Nacional de Rosario. Facultad de Ciencia Política y Relaciones Internacionales; Argentina
¹⁸F-fluoromethylcholine or ¹⁸F-fluoroethylcholine pet for prostate cancer imaging: which is better? A literature revision
The present review was conceived for describing the differences in biodistribution and diagnostic performance of two types of (18)F-radiolabeled choline for positron emission tomography (PET) imaging in prostate cancer (PCa), such as fluoromethylcholine (FCH) and fluoroethylcholine (FEC)
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