Search results

1

Multichannel Intraluminal Impedance and pH Testing - A New Diagnostic Technique for Gastroesophageal Reflux Disease. Own Experience

100%

Wallner G., Solecki M., Huk J., Dąbrowski A., Majewski M., Dombroskyy A.

Polish Journal of Surgery

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2007

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vol. 79

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issue 7

490-495

EN

In 2001 FDA (Food and Drug administration, USA) gave its permission for simultaneous oesophageal intraluminal impedance examination and pH testing in the clinical practice. In 2002 in Porto, Portugal, a committee of international experts proposed a new classification of reflux types.Material and methods. From October 2005 to June 2006, we examined 36 patients sent to the clinic with GERD symptoms using a Sleuth® recording device.Results. The group of 36 patients (19 women and 17 men); mean age of 47 years with a range of 16-74 years) was examined. The mean length of time for the examination was 22 h 47 min, the shortest one lasting 18 h 36 min; brakes were caused by battery failure. 1509 episodes of reflux were confirmed by impedance channels. Only 538 (35.65%) of these reflux episodes were acidic or weakly acidic and 971 (64.35%) were non-acidic. There was one patient without acid reflux episodes during examination and only 12 non-acidic episodes. The proximal extend, defined as 15 cm above the LES, achieved 616 reflux episodes (40.82%). None of the patients had abnormal physical clearing times; 5 had extended chemical clearing times (13.8%) in recumbent positions.Summary. This paper is not a statistical evaluation of a MII-pH study and is only a report of our first experiences with this new diagnostic method. Objective evaluation of symptom correlation to reflux in MII and the chemical character of the refluxate gives a much more precise qualification to the best type of treatment. In cases of non-acidic reflux, MII-pH testing hastens decision making about surgery.

2

Experimental Study of Quantum Graphs with Simple Microwave Networks: Non-Universal Features

88%

Fu Z., Koch T., Antonsen T., Ott E., Anlage S.

Acta Physica Polonica A

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2017

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vol. 132

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issue 6

1655-1660

EN

Quantum graphs provide a setting to test the hypothesis that all ray-chaotic systems show universal wave chaotic properties. Here, an experimental setup consisting of a microwave coaxial cable network is used to simulate quantum graphs. The networks which are large compared to the wavelength, are constructed from coaxial cables connected by T junctions. The distributions of impedance statistics are obtained from experiments on an ensemble of tetrahedral networks. The random coupling model (RCM) is applied in an attempt to uncover the universal statistical properties of the system. Deviations from RCM predictions have been observed in that the statistics of diagonal and off-diagonal impedance elements are different. It is argued that because of the small finite-size quantum graphs utilized here there will be non-universal results.

3

Structural, dielectric, electrical and piezoelectric properties of Ba4SrRTi3V7O30 (R=Sm, Dy) ceramics

88%

Sahoo P., Panigrahi A., Patri S., Choudhary R.

Open Physics

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2008

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vol. 6

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issue 4

843-848

EN

Polycrystalline samples of Ba4SrRTi3V7O30 (R=Sm and Dy), members of the tungsten-bronze family, were prepared using a high-temperature, solid-state reaction technique and studied their electrical properties (using complex impedance spectroscopy) in a wide range of temperature (31–500°C) and frequency (1 kHz-1 MHz). Preliminary structural (XRD) analyses of these compounds show the formation of single-phase, orthorhombic structures at room temperature. The scanning electron micrographs (SEM) provided information on the quality of the samples and uniform distribution of grains over the entire surface of the samples. Detailed studies of the dielectric properties suggest that they have undergone ferroelectric-paraelectric phase transition well above the room temperatures (i.e., 432 and 355°C for R= Sm and Dy, respectively, at frequency 100 kHz). Measurements of electrical conductivity (ac and dc) as a function of temperature suggest that the compounds have semiconducting properties much above the room temperature, with negative temperature coefficient of resistance (NTCR) behavior. The existence of ferroelectricity in these compounds was confirmed from a polarization study.

4

Structural and electrical properties of KCa2Nb5O15 ceramics

88%

Behera B., Nayak P., Choudhary R.

Open Physics

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2008

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vol. 6

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issue 2

289-295

EN

A polycrystalline sample of KCa2Nb5O15 with tungsten bronze structure was prepared by a mixed oxide method at high temperature. A preliminary structural analysis of the compound showed an orthorhombic crystal structure at room temperature. Surface morphology of the compound shows a uniform grain distribution throughout the surface of the sample. Studies of temperature variation on dielectric response at various frequencies show that the compound has a transition temperature well above the room temperature (i.e., 105°C), which was confirmed by the polarization measurement. Electrical properties of the material have been studied using a complex impedance spectroscopy (CIS) technique in a wide temperature (31–500°C) and frequency (102–106 Hz) range that showed only bulk contribution and non-Debye type relaxation processes in the material. The activation energy of the compound (calculated from both the loss and modulus spectrum) is same, and hence the relaxation process may be attributed to the same type of charge carriers. A possible ‘hopping’ mechanism for electrical transport processes in the system is evident from the modulus analysis. A plot of dc conductivity (bulk) with temperature variation demonstrates that the compound exhibits Arrhenius type of electrical conductivity.

5

Measuring Impedances of DC-biased Inductors by Using Vector Network Analyzers

75%

Asmanis G., Stepins D., Asmanis A., Ribickis L.

International Journal of Electronics and Telecommunications

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2019

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vol. 65

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issue 3

6

Simple Wide Frequency Range Impedance Meter Based on AD5933 Integrated Circuit

75%

Chabowski K., Piasecki T., Dzierka A., Nitsch K.

Metrology and Measurement Systems

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2015

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vol. 22

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