Use of lithium niobate detector for measuring X-ray intensity in mammographic range

A detector system that can measure X-ray intensity in the mammographic range of 22 to 36 kVp (equivalent photon energies ofthe beam between 11 and 15 keV) is presented. It consists of a lithium mobate detector and a high-sensitivity current-to-voltage converter.

Viscosity measuring cell using ultrasonic wave mode conversion

This work presents a cell to measure dynamic viscosity of liquids using ultrasonic wave mode conversion from longitudinal to shear wave. The strategy used to obtain the viscosity is based on the measurement of the complex reflection coefficient of shear waves at a solid-liquid interface. Viscosity measurements of automotive oils (SAE90 and SAE140) were obtained in the frequency range from 1 to 10 MHz. These results are compared with the Maxwell model with two relaxation times, showing the dependency of viscosity with frequency. Several parameters affecting viscosity measurements, including the solid material properties, liquid viscosity, and operating frequency are discussed.

PZT FOR MEASURING ENERGY FLUENCE RATE of X-RAY USED IN SUPERFICIAL CANCER THERAPY

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

An in vitro growth inhibition test for measuring the potency of Leptospira spp. Sejroe group vaccine in buffaloes

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Validation of the Brazilian versions of two inventories for measuring oral health-related quality of life of edentulous subjects

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Validation of ACB in vitro and in vivo as a biomagnetic method for measuring stomach contraction

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

In Vivo Models for Measuring Placental Glutatione-S-transferase (GST-P 7-7) Levels: A Suitable Biomarker for Understanding Cancer Pathogenesis

The Glutatione-S-transferases (GSTs) comprise a family of enzymes closely associated with the cell detoxification of xenobiotics. GSTs exist as homo- or heterodimers and have been grouped into at least seven distinct classes. The main function of GSTs is to catalyze the conjugation of reduced glutathione (GSH) to an electrophilic site of a broad range of potentially toxic and carcinogenic compounds, thereby making such compounds less dangerous and enabling their ready-excretion. Placental GST, known as GST-P 7-7, is the main isoform found in normal placental tissue and comprises 67% of the total GST concentration in this tissue. During development, GST-P 7-7 decreases in concentration and is absent in adult tissues. Interestingly, GST-P 7-7 expression has been detected in adult tissues after exposure to carcinogenic agents in several experimental test systems, being considered a reliable biomarker of exposure and susceptibility in early phases of carcinogenesis. In this article, we review a series of studies involving GST-P 7-7 expression as a suitable tool for understanding cancer pathogenesis, especially cancer risk.

Validity of critical frequency test for measuring table tennis aerobic endurance through specific protocol

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Measuring the spectra of high energy neutrinos with a kilometer-scale neutrino telescope

We investigate the potential of a future kilometer-scale neutrino telescope, such as the proposed IceCube detector in the South Pole, to measure and disentangle the yet unknown components of the cosmic neutrino flux, the prompt atmospheric neutrinos coming from the decay of charmed particles and the extra-galactic neutrinos in the 10 TeV to 1 EeV energy range. Assuming a power law type spectra, dphi(nu)/dE(nu)similar toalphaE(nu)(beta), we quantify the discriminating power of the IceCube detector and discuss how well we can determine magnitude (alpha) as well as slope (beta) of these two components of the high energy neutrino spectrum, taking into account the background coming from the conventional atmospheric neutrinos.

Measuring Higgs coupling to tau-leptons at future e(+)e(-) colliders

We perform a complete simulation of the process e(+)e(-) --> tau(+)tau(-)nu(ν) over bar where nu can be an electron, muon or tau neutrino, in the context of a general Higgs coupling to tau-leptons. We analyse various kinematical distributions and obtain the sensitivity regions in the parameter space that can be explored at a future e(+)e(-) collider. In particular, inclusion of W boson fusion enhances the sensitivity significantly.

Photoacoustic procedure for measuring thermal parameters of transparent solids

An application of photoacoustic technique is developed for determining the thermal diffusivity coefficient and the thermal conductivity of transparent materials. The backing material which supports the sample is made optically opaque, i.e., it entirely absorbs the incident light, and the converted heat diffuses through the sample heating the gas in contact with its opposite surface. The method is illustrated by fitting voltage amplitude and phase signals versus the chopping frequency in the photoacoustic cell, according to a theoretical model of heat diffusion. Thermal parameters obtained for three polymers compare very well with results from the literature. (C) 1995 American Institute of Physics.

Ferroelectric ceramic/polymer composite for measuring X-ray intensity in the ortovoltage range

Pyroelectric sensors work as a thermal transducer converting the non-quantified thermal flux into the output measurable quantity of electrical charge, voltage or current. Ferroelectric ceramics and ferroelectric polymers have been extensively used as thermal detectors. More recently the research in the field of pyroelectricity has been concentrated on discovering materials with higher figures of merit (FOM), which means better sensing materials. Composite materials obtained with ferroelectric ceramics embedded in polymer host have received great attention because of their formability, mechanical resistance and the possibility to change their dielectric property varying the volume fraction of ceramic particles. In this work composite films made of modified lead titanate (PZ34) and poly(ether-ether-ketone) (PEEK) were characterized and used as sensing element to measure X-ray intensity in the ortovoltage range (120 - 300 kVp). The sensor response varies from 2.70 V to 0.80 V in the energy fluency range of 6.30 to 37.20 W/m(2). Furthermore the absorbed energy was analyzed as a function of the ionizing energy. The results indicate that the PZ34/PEEK composite with 60/40 vol.% can be useful to monitor X-ray radiation therapy.

A new shadow-ring device for measuring diffuse solar radiation at the surface

A new shadow-ring device for measuring diffuse solar radiation at the surface is presented. In this device the seasonal variation of shadow is followed by moving the detector horizontally. This unique characteristic facilitates its application for long and continuous periods of time. The blocking effect caused by the ring and other related geometric properties are formulated considering the diffuse solar radiation isotropic. The correction factor, shadow size, and ring-detector distance are derived as a function of radius and width of the ring, sun position, and local latitude. The largest blocking occurs during summer, when the ring-detector distance and the shadow width are the smallest, and it is compensated by a smaller blocking effect in the winter period. The performance of the new device is verified comparing daily values of diffuse solar radiation measured simultaneously with a similar device from Kipp & Zonen, Inc. The results show a very good agreement (within 2.5%) between both devices. The new device was also able to reproduce the radiometric properties of the local atmosphere based on 3-yr-long measurements of direct solar radiation using a pyrheliometer. The new device can be applied to estimate daily values of diffuse solar radiation at the surface in the range of 30degreesN-30degreesS with results comparable to other similar apparatuses.

MEASURING HYSTERESIS LOOPS OF FERROELECTRIC POLYMERS USING THE CONSTANT CHARGING CURRENT CORONA TRIODE

A novel method is proposed for measuring the hysteresis loops of ferroelectric polymers. The samples need to have only one electrode and are poled by corona discharge in a constant current corona triode. It is shown how the sample surface potential and the charging current are related to the remanent polarization and coercive field, so that the hysteresis loops can be obtained. An illustrative example is given for samples of beta-PVDF for which the hysteresis cycles were remarkably close to those obtained with the traditional Sawyer-Tower circuit. Values of 80 MV/m and 70 mC/m2 were estimated for the coercive field and remanent polarization, respectively.