abstract：:The heart rate variability is composed of low- and high-frequency fluctuations, which are mediated by the sympathetic and the parasympathetic nervous systems. The baseline and the amplitude of the photoplethysmographic (PPG) signal also show fluctuations in the same frequencies. In the current study, PPG examinations ...

journal_title：Physiological measurement

authors： Nitzan M,Babchenko A,Khanokh B,Landau D

更新日期：1998-02-01 00:00:00

abstract：:Body surface potential maps recorded during catheter pace mapping can facilitate the localization of the site of origin of ventricular tachycardia. In this study, we investigated the value of a realistic computer model of the human ventricular myocardium in generating body surface potential maps as templates for ident...

journal_title：Physiological measurement

authors： Hren R,Horácek BM

更新日期：1997-11-01 00:00:00

abstract：:Dual-energy x-ray absorptiometry (DXA) is a precise, widely used method for measuring bone mineral density (BMD), usually of the lumbar spine and femoral neck. Recent developments, such as a lower x-ray tube current and pixel by pixel analysis, enable smaller bones and thinner tissues volumes, as in the hand, to be me...

journal_title：Physiological measurement

authors： Steel SA,Swann P,Langley G,Langton CM

更新日期：1997-08-01 00:00:00

abstract：:Tetrapolar linear arrays are commonly used in geophysics to explore the vertical distribution of resistivity values in a geological section of a specific point on the earth. This technique, known as vertical electric sounding (VES), uses different electrode configurations. For our experiments, we utilized its more pop...

journal_title：Physiological measurement

authors： Gonzalez CA,offniga O,Padilla LE

更新日期：1997-02-01 00:00:00

abstract：:In the clinical environment the reliable interpretation of EIT images depends on the quality of the data. In the electrically noisy hospital environment the system performance needs to be assessed for each clinical investigation. From the model of noise presented, a figure of merit for comparisons of system performanc...

journal_title：Physiological measurement

authors： Meeson S,Blott BH,Killingback AL

更新日期：1996-11-01 00:00:00

abstract：:We present the results of using electrical impedance tomographic spectroscopy (EITS) to follow the changes in lung water induced by oleic acid. Measurements were made on three goats before and after the injection of oleic acid. In addition to the EITs measurements, lung water was also measured using a double-indicator...

journal_title：Physiological measurement

authors： Brown BH,Flewelling R,Griffiths H,Harris ND,Leathard AD,Lu L,Morice AH,Neufeld GR,Nopp P,Wang W

更新日期：1996-11-01 00:00:00

abstract：:ECG-gated electrical impedance tomographic spectroscopy (EITS) measurements of the lungs were taken on seven normal subjects in the frequency range 9.6 kHz to 614.4 kHz. The results show that in late systole the resistivity p' relative to the R-wave (i.e. p' = 1 at the R-wave) decreases consistently within the lung. I...

journal_title：Physiological measurement

authors： Nopp P,Zhao TX,Brown BH,Wang W

更新日期：1996-11-01 00:00:00

abstract：:The purpose of this study was to determine the validity and reliability of a timed 5 km cycle ergometer ride to predict maximum oxygen uptake (VO2max). Fifty-two healthy volunteers had their VO2max determined during a maximal treadmill run. They also performed a timed 5 km cycle ergometer ride. The resistance setting ...

journal_title：Physiological measurement

authors： Buono MJ,Borin TL,Sjoholm NT,Hodgdon JA

更新日期：1996-11-01 00:00:00

abstract：:Measurement of the velocity of propagation and attenuation of ultrasound (200 kHz) is believed to be a useful non-invasive technique for assessing the mechanical properties of bone. A new method for the determination of ultrasound velocity and attenuation of longitudinal waves in cortical bone was used in vivo and in ...

journal_title：Physiological measurement

authors： Saulgozis J,Pontaga I,Lowet G,Van der Perre G

更新日期：1996-08-01 00:00:00

abstract：:The outside of the skin of the forearm is typically 15 mV more negative than the inside. Stretching the skin causes a reduction in the magnitude of this skin potential V, which we observe as a motion artifact delta V. We seek to determine the origin of this motion artifact by successively stripping 12 layers of the sk...

journal_title：Physiological measurement

authors： de Talhouet H,Webster JG

更新日期：1996-05-01 00:00:00

abstract：:This paper discusses some important issues for the design of electrical impedance measurement systems intended for body fluid shift monitoring, in particular during dialysis treatments. We have studied two common signal generation systems: digital synthesis and carrier recovery. We have found that in prolonged measure...

journal_title：Physiological measurement

authors： Lozano A,Rosell J,Pallás-Areny R

更新日期：1995-11-01 00:00:00

abstract：:This paper represents a reconstruction algorithm using a direct sensitivity matrix (DSM) approach for fast 3D image reconstruction in electrical impedance imaging. The boundary element method (BEM) is used in the construction of this matrix. The first images of a conductivity perturbation inside a sphere are reconstru...

journal_title：Physiological measurement

authors： Morucci JP,Granié M,Lei M,Chabert M,Marsili PM

更新日期：1995-08-01 00:00:00

abstract：:The point spread function (PSF) is the most widely used tool for quantifying the spatial resolution of imaging systems. However, prerequisites for the proper use of this tool are linearity and space invariance. Because EIT is non-linear it is only possible to compare different reconstruction algorithms using a standar...

journal_title：Physiological measurement

authors： Ider YZ,Eyüboğlu BM,Kuzuoğlu M,Leblebïcïoğlu K,Baysal U,Cağlar BK,Bïrgül O

更新日期：1995-08-01 00:00:00

abstract：:The ability to image the impedance changes that accompany neuronal depolarization in the brain would constitute a major advance in neuroscience technology. Unfortunately, these changes are likely to be small and rapid and so difficult to measure. The impedance change at frequencies above 10 kHz, as used by conventiona...

journal_title：Physiological measurement

authors： Boone KG,Holder DS

更新日期：1995-08-01 00:00:00

abstract：:Pulmonary blood volume increase during systole was measured in patients by analysing chest images obtained during ECG gated radionuclide angiography examination. The difference in the total radiation counts between systole and diastole in regions of interest, which included the lungs and the left ventricle, was measur...

journal_title：Physiological measurement

authors： Nitzan M,Mahler Y,Schechter D,Yaffe S,Bocher M,Chisin R

更新日期：1994-11-01 00:00:00

abstract：:Direct digital acquisition of images using a scanning laser ophthalmoscope (SLO) offers several advantages over the conventional fundus camera; in particular, the ability to produce tomographic images using a confocal aperture. This note describes measurements of the performance of an SLO. Spatial resolution, measured...

journal_title：Physiological measurement

authors： Manivannan A,Sharp PF,Forrester JV

更新日期：1994-08-01 00:00:00

abstract：:Two studies concerning multi-frequency impedance measurements are presented. The first uses tetrapolar measurements made on the thorax and the second electrical impedance tomography images, also made from the thorax. The way in which the impedance and the changes in impedance with ventilation depend upon frequency are...

journal_title：Physiological measurement

authors： Brown BH,Barber DC,Wang W,Lu L,Leathard AD,Smallwood RH,Hampshire AR,Mackay R,Hatzigalanis K

更新日期：1994-05-01 00:00:00

abstract：:This paper describes a method of reducing the influence of the data error caused by non-ideal boundary shape and electrode placement on reconstructed images. A data calibration and a modified Newton-Raphson reconstruction are combined in the method to ensure rapid convergence and small reconstruction error. The method...

journal_title：Physiological measurement

authors： Li J

更新日期：1994-05-01 00:00:00

abstract：:In this study, the selection of coil configuration parameters (coil radius and coil centre shift) for induced current EIT using circular coils is investigated. An alternative coil configuration is suggested, which produces approximately linear (spatially) magnetic fields in order to strengthen the currents in the cent...

journal_title：Physiological measurement

authors： Gençer NG,Ider YZ

更新日期：1994-05-01 00:00:00

abstract：:The changes in haemoglobin oxygenation (SO2) occurring in the tuberculin reaction in human skin were measured using macro- and micro-lightguide spectrophotometry and the results compared. A significant difference was found between the measurements from the respective instruments, demonstrating that the micro-lightguid...

journal_title：Physiological measurement

authors： Newton DJ,Harrison DK,Delaney CJ,Beck JS,McCollum PT

更新日期：1994-05-01 00:00:00

abstract：:We used finite element analysis to study the relationship between the intraventricular blood conductance and the right ventricular volume. Previous studies reported a quasi-linear dependence between these two quantities. We quantified the effects of the resistivities of the surrounding tissues (e.g. heart wall, lungs)...

journal_title：Physiological measurement

authors： Panescu D,Webster JG,Stratbucker RA

更新日期：1994-02-01 00:00:00

abstract：:Using a primary coil that induces eddy currents in a volume conductor, and a pair of secondary coils configured to form a differential transformer, it is possible to measure the conductivity of a volume conductor by the magnetic fields of the induced eddy currents. This method is especially favourable for measuring im...

journal_title：Physiological measurement

authors： Netz J,Forner E,Haagemann S

更新日期：1993-11-01 00:00:00

abstract：:A method is described that accounts for multichannel brain field data (EEG) epochs, after transformation into the frequency domain, by a single oscillating dipole source in terms of phase angles. The method produces a potential distribution for each frequency point ('FFT dipole approximation'). These maps can be subje...

journal_title：Physiological measurement

authors： Michel CM,Henggeler B,Brandeis D,Lehmann D

更新日期：1993-11-01 00:00:00

abstract：:Neuromagnetic recordings were used to check if electrical stimulation of the auditory nerve in cochlear-implant patients activates cortical auditory areas in a similar manner as acoustic stimulation in normal hearing subjects or whether the excitation processes are different. The waveform of the evoked magnetic field ...

journal_title：Physiological measurement

authors： Pelizzone M

更新日期：1993-11-01 00:00:00

abstract：:Current methods for analysing foetal heart rate (FHR) patterns have yet to meet their full potential in the recognition of hypoxia in the foetus. Following the recent suggestion that fractal analysis can be applied to FHR recordings, the current paper describes a method for distinguishing two simultaneous fractal dime...

journal_title：Physiological measurement

authors： Gough NA

更新日期：1993-08-01 00:00:00

abstract：:The measurement of the complex respiratory impedance at a high temporal resolution is described. The measurement of impedance is correlated with the breathing cycle using electrical transthoracic impedance. This allows the determination of the complex impedance at any fixed point in the respiratory cycle, which result...

journal_title：Physiological measurement

authors： van der Putten WJ,MacLeod D,Prichard JS

更新日期：1993-08-01 00:00:00

abstract：:A method was developed for simultaneously measuring plasma resistance, cell interior resistance and cell membrane capacitance of blood. A three-element circuit model for simulating the impedance of blood was evaluated by comparing measured and calculated impedance frequency curves and was found feasible. The values of...

journal_title：Physiological measurement

authors： Zhao TX,Jacobson B,Ribbe T

更新日期：1993-05-01 00:00:00

abstract：:An accurate reproducible measurement of left ventricular volume is important in the evaluation of cardiac disease. Four methods of left ventricular volume measurement by radionuclide ventriculography have been compared and their reproducibility assessed in a patient group. The methods studied were a geometric method, ...

journal_title：Physiological measurement

authors： Thorley PJ,Sheard KL,Rees MR

更新日期：1993-02-01 00:00:00