875 research outputs found
Temperature Increase Dependence on Ultrasound Attenuation Coefficient in Innovative Tissue-mimicking Materials
Although high intensity focused ultrasound beams (HIFU) have found rapid agreement in clinical environment as a tool for non
invasive surgical ablation and controlled destruction of cancer cells, some aspects related to the interaction of ultrasonic waves
with tissues, such as the conversion of acoustic energy into heat, are not thoroughly understood. In this work, innovative tissue-
mimicking materials (TMMs), based on Agar and zinc acetate, have been used to conduct investigations in order to determine a
relation between the sample attenuation coefficient and its temperature increase measured in the focus region when exposed to an
HIFU beam. An empirical relation has been deduced establishing useful basis for further processes of validations of numerical
models to be adopted for customizing therapeutic treatments
Longitudinal study of physical activity in college students: Testing self-determination theory based on stages of change
The main purpose of this study was to longitudinally test the relationships of Self Determination Theory variables on physical activity, analyzing the model based on stages of change. The study is a longitudinal and quantitative research. We have developed a longitudinal cross-lagged design for structural equation models of three time points and multi-group analysis. Participants were 772 Spanish college students from the University of Zaragoza (M = 19.74, SD = 2.76) studying several degrees. Participants completed different self-reports, assessing: physical activity, stages of change, motivation and basic psychological needs, at three time points (November, January and March). The analysis indicated that intrinsic motivation positively predicted physical activity at the 3-time points, both directly and indirectly. Intrinsic motivation was negatively predicted by autonomy and positively predicted by competence (from time point 2 to 3). No relationships were found with relatedness for the entire sample. Regarding the stages of change multi-group analysis were run: in the low active group, we found a negative relationship between relatedness and physical activity, and a positive association between competence and intrinsic motivation and physical activity, whereas intrinsic motivation did not predict physical activity. Our findings showed that intrinsic motivation was the most consistent predictor of physical activity. The competence need played an essential role in intrinsic motivation and physical activity for both active and passive subjects. However, the basic psychological needs have not worked as indicated by the theory when it was examined longitudinally. The findings of the study highlight the need for different strategies to improve physical activity levels according to the stages of change
Improving the light collection efficiency of silicon photomultipliers through the use of metalenses
Metalenses are optical devices that implement nanostructures as phase shifters to focus incident light. Their compactness and simple fabrication make them a potential cost-effective solution for increasing light collection efficiency in particle detectors with limited photosensitive area coverage. Here we report on the characterization and performance of metalenses in increasing the light collection efficiency of silicon photomultipliers (SiPM) of various sizes using an LED of 630 nm, and find a six to seven-fold increase in signal for a 1.3×1.3 mm² SiPM when coupled with a 10-mm-diameter metalens manufactured using deep ultraviolet stepper lithography. Such improvements could be valuable for future generations of particle detectors, particularly those employed in rare-event searches such as dark matter and neutrinoless double beta decay
Robotic prostatectomy : an update on functional and oncologic outcomes
Since the first procedure performed in 2000, robotic-assisted radical prostatectomy (RARP) has been rapidly gaining increasing acceptance from both urologists and patients. Today, RARP is the dominant treatment option for localised prostate cancer (PCa) in the United States, despite the absence of any prospective randomised trial comparing RARP with other procedures. Robotic systems have been introduced in an attempt to reduce the difficulty involved in performing complex laparoscopic procedures and the related steep learning curve. The recognised advantages of this kind of minimally invasive surgery are three-dimensional (3D) vision, ten-fold magnification, Endowrist technology with seven degrees of freedom, and tremor filtration. In this article, we examine this technique and report its functional (in terms of urinary continence and potency) and oncologic results. We also evaluate the potential advantages of RARP in comparison with open and laparoscopic procedures. Copyright
A Method To Characterize Metalenses For Light Collection Applications
Metalenses and metasurfaces are promising emerging technologies that could
improve light collection in light collection detectors, concentrating light on
small area photodetectors such as silicon photomultipliers. Here we present a
detailed method to characterize metalenses to assess their efficiency at
concentrating monochromatic light coming from a wide range of incidence angles,
not taking into account their imaging quality
Utilidad de los agonistas, moduladores selectivos y antagonistas puros del receptor de estrógenos en estudios morfofuncionales del útero de la rata
De acuerdo con el Instituto Nacional de la Salud, la especie murina es una de las especies más importantes en el estudio de la fisiología y de un gran número de procesos que tienen lugar en el organismo, tanto en la especie humana como en los animales. Se estima que en el 90-95 % de los estudios realizados en biomedicina se utilizan ratones y ratas. En la rata, la función reproductora es debida a las hormonas esteroideas ováricas, estrógenos (E) y progesterona (P). Durante las distintas fases del ciclo estral, el útero sufre cambios morfológicos y funcionales que dependen de la acción de los E y la P y que incluyen la proliferación celular y la síntesis de receptores de progesterona en el epitelio, y la proliferación celular del estroma y su consecuente decidualización, respectivamente. La acción de los E y la P en el útero está mediada por receptores intracelulares, los receptores de E (RE) y los receptores de P (RP). Ambos receptores tienen dos isofomas, α y β para los RE y A y B para los RP. Estudios previos realizados tanto en ratones knock-out (KO) para una de las isoformas del RE y las dos del RP, como en ratas ovariectomizadas (OVX) a las que se administran agonistas estrogénicos selectivos para una de las isoformas del RE, han revelado que la mayoría de las acciones de los E en el útero son mediadas por la isoforma α del RE, aunque en la actualidad el papel específico de cada una de las isoformas se conoce solo parcialmente. Tanto el conocimiento molecular del RE como los avances farmacológicos han permitido el desarrollo de nuevos agentes agonistas y antagonistas para las distintas isoformas del RE que hacen posible estudiar la acción que desempeña en el útero cada una de las isoformas del RE
Ovarian stimulation with FSH reduces phosphorylation of gonadotrope progesterone receptor and LH secretion in the rat
Administration of human FSH(hFSH) to cyclic rats during the dioestrous phase attenuates progesterone receptor (PR)-dependent events of the
preovulatory LH surge in pro-oestrus. The increased bioactivity of the putative ovarian gonadotropin surge inhibiting/attenuating factor
induced by hFSH treatment is not associated with a decrease in PR protein expression, and the possibility of its association at a PR
posttranslational effect has been raised. The present experiments aimed to analyse PR phosphorylation status in the gonadotrope of ratswith
impaired LH secretion induced by in vivo hFSH injection. Two experimental approaches were used. First, incubated pro-oestrous pituitaries
from hFSH-injected cycling and oestrogen-treated ovariectomized (OVX) rats were used to analyze the effect of calyculin, an inhibitor of
intracellular phosphatases, on PR-dependent LH release, which was measured in the incubation medium by RIA. Second, pituitaries taken
from hFSH-injected intact cycling and OVX rats and later incubated with P or GNRH1 were used to assess the phosphorylation rate of
gonadotrope. The latter was analysed in formalin-fixed, paraffin-embedded tissue sections by immunohistochemistry using a MAB that
recognizes the phosphorylated (p) form of PR at Ser294. Calyculin reduced the ovary-mediated inhibition of hFSH in GNRH1-stimulated LH
secretion. In addition, the immunohistochemical expression of pSer294 PR was significantly reduced after ovarian stimulation with hFSH in
pituitaries frompro-oestrous rats incubated with PorGNRH1.Altogether, these results suggested that the ovarian-dependent inhibitory effect
of FSH injection on the preovulatory LH secretion in the rat may involve an increase in dephosphorylation of PR
Energy Resolution studies for NEXT
This work aims to present the current state of simulations of
electroluminescence (EL) produced in gas-based detectors with special interest
for NEXT --- Neutrino Experiment with a Xenon TPC. NEXT is a neutrinoless
double beta decay experiment, thus needs outstanding energy resolution which
can be achieved by using electroluminescence. The process of light production
is reviewed and properties such as EL yield and associated fluctuations,
excitation and electroluminescence efficiencies, and energy resolution, are
calculated. An EL production region with a 5 mm width gap between two infinite
parallel planes is considered, where a uniform electric field is produced. The
pressure and temperature considered are 10 bar and 293 K, respectively. The
results show that, even for low values of VUV photon detection efficiency, good
energy resolution can be achieved: below 0.4 % (FWHM) at 2.458
MeV
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