Abstract：
:The paper describes an investigation in which it is shown that small positive voltage pulses applied to an external conductor placed against the photocathode of a photomultiplier tube can be used to switch the photocathode completely off for the duration of the pulses. This suggests that a photomultiplier tube with a multisegment photocathode can be constructed, the individual cathode segments of which can be switched off independently by means of such pulses. A theoretical explanation for the effect is provided with the aid of a simple circuit model for the photocathode. Analysis of the model also shows that it is possible to identify the particular cathode segment in which a photon is detected when a pulse is recorded at the phototube's anode. A phototube with these characteristics can have important implications for positron emission tomography, as it can provide improved spatial resolution, simultaneous multislice capability and the ability to eliminate distortion due to dead-time effects at high count rates.
journal_name
Med Biol Eng Computjournal_title
Medical & biological engineering & computingauthors
Woldeselassie Tdoi
10.1007/BF02441486subject
Has Abstractpub_date
1989-05-01 00:00:00pages
281-7issue
3eissn
0140-0118issn
1741-0444journal_volume
27pub_type
杂志文章abstract：:The role of alveolar macrophages in the process of the human lung clearance is summarised. Three patterns of alveolar macrophage (AM) displacement on the surface of alveolus are distinguished depending on the loading of the surface with insoluble deposits, i.e. directional, directional with small stochastic noise and ...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/BF02522517
更新日期：1995-07-01 00:00:00
abstract：:Density assessment and lesion localization in breast MRI require accurate segmentation of breast tissues. A fast, computerized algorithm for volumetric breast segmentation, suitable for multi-centre data, has been developed, employing 3D bias-corrected fuzzy c-means clustering and morphological operations. The full br...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/s11517-016-1484-y
更新日期：2017-01-01 00:00:00
abstract：:Variations in the amplitude and period of essential and Parkinsonian tremors were studied. It was found that the variations in frequency (or period) were mostly similar to the white noise, with the standard deviation typically less than 10% of the mean, whereas the variations in amplitude were much larger, with standa...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/BF02344710
更新日期：2004-05-01 00:00:00
abstract：:Detection and classification methods have a vital and important role in identifying brain diseases. Timely detection and classification of brain diseases enable an accurate identification and effective management of brain impairment. Brain disorders are commonly most spreadable diseases and the diagnosing process is t...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章,评审
doi：10.1007/s11517-020-02256-z
更新日期：2020-11-01 00:00:00
abstract：:The passive and active properties of the cochlear outer hair cell are studied. The outer hair cell is currently considered the major candidate for the active component of mammalian hearing. Understanding of its properties may explain the amplification and sharp frequency selectivity of the ear. To analyse the cell beh...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/BF02513294
更新日期：1999-03-01 00:00:00
abstract：:Obstructive sleep apnea syndrome (OSAS) is a major public health problem. The golden reference for diagnosing OSAS is the sleep-laboratory based polysomnography (PSG). However, screening of population for OSAS may be practical and cost efficient only through ambulatory home recordings. In this work we aimed to design,...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/s11517-008-0418-8
更新日期：2009-01-01 00:00:00
abstract：:The regulation of cerebral blood flow (CBF) following changes in arterial blood pressure (ABP) and end-tidal pCO2 (EtCO2) are of clinical interest in assessing cerebrovascular reserve capacity. Linear finite-impulse-response modelling is applied to ABP, EtCO2 and CBF velocity (CBFV, from transcranial Doppler measureme...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/BF02345749
更新日期：2000-09-01 00:00:00
abstract：:To describe upper airway obstruction in patients with sleep apnea syndrome, the steady state solutions of a simple model of local pharyngeal obstruction were studied. Importantly, the present model embodies a series of two individualised elements, each having its own compliance, which enables the consideration, from a...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/BF02510972
更新日期：1997-11-01 00:00:00
abstract：:Measurements of the dielectric properties of healthy and atherosclerotic human artery tissues were made in the frequency range of 100 Hz-100 kHz and temperatures from 22 to 260 degrees C. The temperature dependencies of the dielectric parameters for healthy tissues reveal distinctively the temperature ranges correspon...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/s11517-007-0181-2
更新日期：2007-06-01 00:00:00
abstract：:Impedance cardiography is a low-cost noninvasive technique, based on monitoring of the thoracic impedance, for estimation of stroke volume (SV). Impedance cardiogram (ICG) is the negative of the first derivative of the impedance signal. A technique for beat-to-beat SV estimation using impedance cardiography and artifi...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/s11517-017-1752-5
更新日期：2018-06-01 00:00:00
abstract：:Mean arterial pressure (MAP) is determined in most automated oscillometric blood pressure devices, but its derivation has been little studied. In this research, different techniques were studied and compared with the auscultatory technique. Auscultatory systolic and diastolic blood pressure (SBP and DBP) were obtained...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/s11517-010-0694-y
更新日期：2011-01-01 00:00:00
abstract：:The CellDrum technology (The term 'CellDrum technology' includes a couple of slightly different technological setups for measuring lateral mechanical tension in various types of cell monolayers or 3D-tissue constructs) was designed to quantify the contraction rate and mechanical tension of self-exciting cardiac myocyt...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/s11517-009-0552-y
更新日期：2010-01-01 00:00:00
abstract：:During scoliosis instrumentation surgery, it is difficult for surgeons fully to track vertebral motion in 3D, because only the posterior elements of the spine are exposed. Different intra-operative modelling approaches are evaluated using a registration technique that matches intra-operative measurements with a 3D pre...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/BF02513328
更新日期：1999-07-01 00:00:00
abstract：:Biological variation in branching patterns is likely to affect perfusion of tissue. To assess the fundamental consequences of branching characteristics, 50 stochastic asymmetrical coronary trees and one non-stochastic symmetrical branching tree were generated. In the stochastic trees, area growth, A, at branching poin...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/s11517-006-0139-9
更新日期：2007-01-01 00:00:00
abstract：:This work addresses the problem of estimating the conduction velocity (CV) of single motor unit (MU) action potentials from surface EMG signals detected with linear electrode arrays during voluntary muscle contractions. In ideal conditions, that is without shape or scale changes of the propagating signals and with add...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/BF02344807
更新日期：2001-03-01 00:00:00
abstract：:Heart sounds can be considered as mechanical fingerprints of myocardial function. The third heart sound normally occurs in children but disappears with maturation. The sound can also appear in patients with heart failure. The sound is characterised by its low-amplitude and low-frequency content, which makes it difficu...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/BF02345957
更新日期：2005-03-01 00:00:00
abstract：:Thousands of patients receive human tissue grafts every year. Developments in cell and tissue engineering have also increased considerably the number of available products of human origin. France has very strict regulations, in part stimulated by problems of public health and ethics that have emerged in recent years a...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/BF02344783
更新日期：2000-03-01 00:00:00
abstract：:A thin-walled capsule, modelled as an incompressible liquid droplet contained in a thin flexible membrane, was allowed to adhere onto a rigid substrate. The contact mechanics were formulated, based on linear elasticity, to portray quantitatively the relationships between osmotic inflation, contact area and angle, memb...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/BF02345154
更新日期：2001-09-01 00:00:00
abstract：:Time-varying filtering techniques are applied to the problem of baseline correction by letting the cut-off frequency of a linear filter be controlled by the low-frequency properties of the ECG signal. The time-varying filter is implemented as a bank of linear low-pass filters, in which each filter has a slightly diffe...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/BF02441986
更新日期：1993-09-01 00:00:00
abstract：:The changes in the power spectra of single-fibre extracellular action potentials (SFEAPs) generated in an infinite anisotropic frequency-dependent volume conductor, which occurred as a result of alterations in the propagation velocity v and duration T(in) of the intracellular action potential (IAP) were analytically d...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/BF02446167
更新日期：1992-07-01 00:00:00
abstract：:During the study of velocities in the human ascending aorta it became necessary to establish a method for two-dimensional velocity profiles from discrete velocity data obtained from different heartbeats and with different techniques. A descriptive geometrical model was therefore developed and expanded to 16 elements e...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/BF02442319
更新日期：1991-09-01 00:00:00
abstract：:The use of piezo-resistive uni-axial accelerometer signals in gait analysis is complicated by the fact that the measured signal is composed of different types of acceleration. The aim of the study is to obtain insight into the signal from a tangential accelerometer attached to the thigh during walking. Six subjects wa...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/BF02344868
更新日期：2000-11-01 00:00:00
abstract：:A new method of quantifying dermal perfusion on a regional basis using a dynamic thermographic technique is investigated. The technique is based on the relationship between dermal perfusion and the rate of skin surface reheating following the application of a transient cold challenge predicted by a theoretical model. ...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/BF02441468
更新日期：1989-09-01 00:00:00
abstract：:Blood oxygenation level is an important measure that can be used alongside functional magnetic resonance imaging data in order to obtain closer correlates of neuronal activation. A robust estimate of this measure has thus far not been demonstrated. This is mainly due to the lack of knowledge of the underlying paramete...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/s11517-012-0886-8
更新日期：2012-05-01 00:00:00
abstract：:To elucidate the mechanisms of localisation of intimal hyperplasia in anastomosed arteries, the effects of flow disturbances on the transport of low-density lipoproteins (LDLs) from the flowing blood to the wall of end-to-end anastomosed arteries, with and without a moderate stenosis, were studied theoretically by mea...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/BF02345458
更新日期：2002-09-01 00:00:00
abstract：:Magnetic nanoparticles for therapy and diagnosis are at the leading edge of the rapidly developing field of bionanotechnology. In this study, we have theoretically studied motion of magnetic nano- as well as micro-particles in the field of cylindrical Halbach array of permanent magnets. Magnetic flux density was model...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/s11517-010-0636-8
更新日期：2010-08-01 00:00:00
abstract：:Pain control in conscious patients was investigated using a push-button, demand-driven supply of drugs. A fuzzy logic patient-controlled analgesia (PCA) algorithm was compared with a conventional algorithm, for alfentanil administration in extracorporeal shock-wave lithotripsy. The conventional PCA algorithm used an i...
journal_title：Medical & biological engineering & computing
pub_type： 临床试验,杂志文章
doi：10.1007/BF02347706
更新日期：2002-01-01 00:00:00
abstract：:The present study describes a new methodological approach which allows the separate analysis and quantitative determination of the viscous and elastic components of human hair using a computerised experimental system. In a first series of experiments subsequent to the estimation of the cross-sectional surface area of ...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/BF02446198
更新日期：1992-01-01 00:00:00
abstract：:The aim of this study was to evaluate feasibility and reproducibility of quantitative assessment of colonic morphology on CT colonography (CTC). CTC datasets from 60 patients with optimal colonic distension were assessed using prototype software. Metrics potentially associated with poor endoscopic performance were cal...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/s11517-016-1529-2
更新日期：2017-03-01 00:00:00
abstract：:A compression algorithm for electrocardiogram signals is presented, based on an auto-associative neural network. Issues of weight and activation coding are considered, and compression performances of various network sizes are compared. A unique feature is the performance improvement achieved using DC level removal. A ...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/BF02523019
更新日期：1995-11-01 00:00:00
