Change In Count Rate Research Articles

Bisoniana 108. Seasonal changes in the white blood cell count and blood cell sedimentation rate in the European bison Bison bonasus

Two hundered and forty European bison Bison bonasus (Linnaeus, 1758) were divided into 4 groups based on age and sex, and seasonal changes in the white blood cell count and blood cell sedimentation rate were studied.

ＡＥによるチョップドストランド型ＣＦＲＰの破壊機構の解明

In this paper, the acoustic emission method was used for clarifying the fracture mechanism of carbon fiber chopped strand reinforced plastics with a center crack through the thinkness in tensile deformation. It was observed that the load vs. displacement curve could be divied into five regions, and the fracture mechanism was made clear by combining the behaviour of acoustic signals in each region with SEM observation. The generation of initial stable cracks was clearly shown in the relationship between stress intensity factor and acoustic cumulative energy and that between stress intensity factor and acoustic cumulative events. The development of stable cracks was noticed by the change in acoustic event count rate. There existed two peaks in amplitude distribution. A three dimensional amplitude distribution was made, which gave the detailed relationship between the acoustic amplitude and the failure process. From this distribution, the acoustic event count rate can be classified into two types with low and high amplitude events which have different characteristics of microfracture mechanisms. Furthermore, a model was proposed to explain the pulled-out failure of chopped strand tapes.

Acoustic emission monitoring of the wear process

Acoustic emissions are generated at the sites of the fundamental processes resulting in material wear and so are an attractive possibility for continuously monitoring wear and for basic studies of the wear process. Changes in wear rate and acoustic emission activity were measured across the mild-severe wear transition in the sliding of metals. The intent was to characterize these changes in wear behavior in terms of acoustic emission characteristics and to determine the usefulness of acoustic emission measurements for the study of wear. Experimental results showed that changes in acoustic emission count rates correspond to changing wear rate. Acoustic emission amplitude distributions as well as acoustic emission energy measurements indicated a strong potential for the use of these two parameters in the identification of different modes of failure during the wear process.

Coding of temporal parameters of complex sounds by frog auditory nerve fibers

1. Physiological recordings were made from single auditory fibers in the frog eighth nerve to determine quantitatively how the different behaviorally relevant temporal parameters (the signal rise-fall time, duration, and rate of amplitude modulation) of complex sounds are encoded in the auditory periphery. Individual temporal parameters were varied. Response functions (RFs) were constructed with respect to each of these parameters using each unit's best excitatory frequency (BF) as the carrier. 2. In response to a change in signal rise-fall time, auditory nerve fibers showed little change in the mean spike count or firing rate, i.e., all fibers displayed ALL-PASS RFrfts. But the transient components, particularly the early phasic component, of responses varied with rise-fall times; these components were more pronounced in the responses to stimuli with shorter rise-fall times. 3. In response to an increase in signal duration, auditory nerve fibers showed a corresponding increase in firing duration and thus in the mean spike count, giving rise to HIGH-PASS RFdurs. The shape of response curves differed among fibers; the difference appeared to be related to the fiber's temporal adaptation characteristic. When the firing rate was measured, all fibers displayed higher mean firing rates in response to shorter duration stimuli than they did to longer duration stimuli, thus giving rise to LOW-PASS response functions. 4. To determine the response transfer functions to modulation rate, pulsed (PAM) and sinusoidally (SAM) amplitude-modulated signals were used. These signals differed substantially in terms of their envelopes and how they varied with AM rate. Data were analyzed by 1) plotting spike counts against the AM rate to derive modulation transfer functions (MTFspks) and 2) plotting synchronization coefficients (SCs) against the AM rate to generate MTFscs. 5. In response to PAM stimuli, all fibers showed an increase in mean spike count with modulation frequency over the range examined, giving rise to HIGH-PASS MTFspks. 6. For SAM stimuli, the average energy and duty cycle are independent of AM rate. Most (79%) auditory fibers showed little selectivity for AM rate over a range of 5-400 Hz, giving rise to ALL-PASS MTFspks. The remaining auditory fibers displayed LOW-PASS MTFspks, i.e., there was a distinct decline in the mean spike count with increasing AM rate. 7. In response to PAM stimuli, most fibers showed good response synchrony at low AM rates but the SC declined with an increase in the AM rate (i.e., LOW-PASS MTFscs). The cut-off frequency was typically very high, averaging 90 pulses/s.(ABSTRACT TRUNCATED AT 400 WORDS)

Thermal and Mechanical Properties of Thermal Barrier Coatings

The material property measurements of thermal bamer coatings from cyclic fumaa, thermal rig, thermal expansion, acoustic emission and tensile adhesion test methods are critically examined. Some basic engineering properties of coatings such as the elastic modulus have not been measured without ambiguity. Data of this nature is essential to the success of modeling studies. Insights into the mechanical properties of coatings have been gained by carrying out instrumented tensile adhesion tests. The general view of the coating deformation process is that the individual lamelhe slide wer each other and this promotes a pseudoductility response in the coatings. Monitoring of the acoustic emission response of coatings during thermal cycling aperiments suggests that there are two distinct cracking processes. The macrocracking behavior, indicated by a change in the acoustic emission count rate, is the predominant mechanism which leads to coating failure. It is further shown that the acceptance tests used by industry, although useful in ranking coatings in terms of a particular property, present no fundamental knowledge concerning the material properties of coatings. It is only when the phenomenological characteristics of the thermo-mechanical response of coatings is undemtood that coating development will substantially progress.

Temporal instabilities associated with a planar high purity germanium detector

Experiments have been performed which show that a grooved planar high purity germanium semiconductor detector may give rise to time variant counting rates in energy regions below prominent spectral peaks. It is postulated that this effect is due to prolonged or incomplete charge collection in the vicinity of the bottom of the groove, and is caused by distortions in the applied electric field in this region. Such effects may lead to changes in the minimum detectable count rate in X-ray fluorescence measurements; these can be reduced by collimating incident photons on the central region of the detector but the resulting reduction in efficiency lowers the overall sensitivity.

Applications of large barium fluoride scintillators to in-beam gamma-ray spectroscopy

Properties of large-volume BaF 2 scintillators have been studied and first experiences of applications to in-beam γ-ray spectroscopy are reported. Energy resolutions of 9.1% at 662 keV and 6.3% at 1332 keV γ-ray energies were obtained. A time resolution of 375 ps FWHM was measured using a 60Co source. Gain variations of the phototubes from changes in count rate could be limited to a 2% level. Lifetimes have been measured for the first 2 + state of 152Sm using a 152Eu source and the 5 1 − state of 40Ca at 4.49 MeV populated in the (α, α′) reaction.

Influence of Instrument Parameters on Nonspectroscopic Interferences in Inductively Coupled Plasma-Mass Spectrometry

The effect of ion lens voltage settings and plasma conditions on nonspectroscopic interferences has been studied. The change in ion count rate for 7Li, 10B, 45Sc, and 89Y in the presence of Na, K, Sr, and Cs under a variety of experimental conditions is reported. The ion lens voltage setting did not affect the degree of nonspectroscopic interferences with the use of the Einzel ion optic system. Suppression effects were increased when the power was increased and the sampling depth decreased. Changes in nebulizer pressure resulted in interference trends, which varied with the concomitant element being studied. Sodium caused a decrease in interference effects with increasing nebulizer pressure, whereas Cs caused an increase under the same experimental conditions. Suppression of analyte ion count rate increased with increasing sample solution uptake rate and increasing atomic mass of concomitant elements.

An implementation of the pulse injection technique for dead-time and pileup corrections in gamma spectroscopy suitable for automated systems

A convenient method of injecting reference pulses into a gamma ray spectrum is described. The method utilizes an injection rate which is proportional to the gross gamma count rate; the circuit described automatically adjusts the pulse injection rate as the gross count rate changes. The method has been successfully tested using a wide dynamic range spectroscopy system. This injection technique has been installed in an automated scanning system designed for unattended operation. Good results have been obtained for measurement of hundreds of spectra having wide gross count rate variations.

Electron Beam-Induced Mass Loss in Freeze-Dried Tissue and Protein Samples

Quantification in biological x-ray microanalysis depends on accurate evaluation of mass loss. Although several studies have addressed the problem of electron beam induced mass loss from organic samples (eg., 1,2). uncertainty persists as to the dose dependence, the extent of loss, the elemental constituents affected, and the variation in loss for different materials and tissues. in the work described here, we used x-ray counting rate changes to measure mass loss in albumin (used as a quantification standard), salivary gland, and muscle.In order to measure mass loss at low doses (10-4 coul/cm2 ) large samples were needed. While freeze-dried salivary gland sections of the required dimensions were available, muscle sections of this size were difficult to obtain. To simulate large muscle sections, frog or rat muscle homogenate was injected between formvar films which were then stretched over slot grids and freeze-dried. Albumin samples were prepared by a similar procedure. using a solution of bovine serum albumin in water. Samples were irradiated in the STEM mode of a JEOL 100C.

A Quantitative Approach to Gravel Pack Evaluation

Summary Gravel pack logging has been used during the past few years to evaluate internal gravel packs qualitatively. This paper describes a study that was made under laboratory paper describes a study that was made under laboratory conditions to develop a quantitative evaluation procedure. Field logs are shown that confirm the validity of the laboratory measurements. Introduction Previous test well experiments confirmed the application Previous test well experiments confirmed the application of wireline logging techniques to provide a qualitative evaluation of gravel packs. It soon became apparent that a reliable method of quantitative evaluation was desirable. Laboratory measurements have been made to quantify the log response to percent void space in the gravel pack. Measurements were made in 7-in., 32-lbm 117.8-cm, 14.5-kg] casing; 7%-in., 29.7-lbm [19.4-cm, 13.5-kg] casing; and 9%-in., 47-lbm [24.4-cm, 21 -kg] casing. Five standard screens of different sizes and five tubing blank sections of different sizes were used. Table 1 summarizes the hardware used in the laboratory experiments. To establish tool response data to varying percentages of gravel, series of fins were fitted to each size tubing and screen. This enabled data to be collected for 0, 33, 66, and 100% gravel packs. Fig. 1 shows a top view of the laboratory model. Four different types and weights of fluids and high-specification 40/60 resieved gravel were used in the experiments. The measurements taken clearly demonstrate that the gravel pack logging tool does respond to changes in percent pack and that a quantitative approach to the percent pack and that a quantitative approach to the interpretation of the field logs can be made. This paper describes the procedures used and the conditions under which the laboratory measurements were made. Comparisons between laboratory data and actual field logs are given. Theory Gravel Pack Logging Tool The gravel pack logging tool uses a gamma ray source and a single gamma ray detector. The source emits gamma rays radially into the borehole and the surrounding area and is focused upward toward the detector. Fig. 2 shows a schematic of the tool configuration. Some of the gamma rays are scattered back to the detector. The number of gamma rays returning to the detector is an indication of the density of the material through which they traveled. High-density materials cause more gamma rays to be slowed down and absorbed, and low-density materials allow more gamma rays to be returned to the detector. In a gravel-packed well, everything remains constant except the annular space between the casing and the screen or tubing. This space can be totally filled with gravel, partially filled with gravel, or have void spaces containing no gravel. In each of these cases, the volume that is not filled with gravel is filled with some type of fluid of a known density. Since the density of the gravel is different from the density of the fluid, it is possible to correlate gamma ray count rates to percent pack. percent pack. Description of Laboratory Models The laboratory models consisted of 7-in., 32-lbm [17.8-cm, 14.5-kg] casing; 7 5/8-in., 29.7-lbm [19.4-cm, 13.5-kg] casing; and 9 5/8-in., 47-lbm [24.4-cm, 21-kg] casing. Each was cemented into steel cylinders 22 in. [56 cm] in diameter and 80 in. [2 m] long. Centralizers were placed on the casing to ensure that they were centered placed on the casing to ensure that they were centered in the cylinders before they were cemented into place. Fig. 3 shows how the models were constructed. Rubber fins were attached to the screen and tubing to divide the annular space into three equal parts. This enabled data to be collected for four different percentages of gravel pack. Four different fluids were used in making the measurements. They were 6.8-lbm [3-kg] diesel, 9.5-lbm [4.3-kg] salt water, 11-lbm [5-kg] calcium chloride, and 14.2-lbm [6.4-kg] calcium bromide. Log Response Measurements The first laboratory measurements were made with 9 5/8-in., 47-lbm [24.4-cm, 21-kg] casing, 31/2-in., 12.37-lbm 18.9-cm, 5.6-kg] screen, and 11-lbm [5-kg] calcium chloride. The pack was varied from 0 to 100% and the corresponding change in count rate was noted. Fig. 4 shows that the change in count rate as the percent pack is varied is a linear function. Fig. 4 also shows that this linear response was verified by making measurements in 4-in., 13.23-lbm [10-cm, 6-kg] screen and in 4-in., 9.5-lbm [10-cm, 4.3-kg] tubing. Since the response had been verified as being linear, further measurements on other hardware were made only at 0 and 100% pack. Further measurements were made in 9 5/8-in. [24-cm] casing with 41/2- and 5-in. [11-and 13-cm] screens and 4 1/2- and 5-in. [11- and 13-cm] tubing. They were also made in 7 5/8-in. [19-cm] casing with 2 7/8,-, 4 1/2-, and4 1/2-in. [7.3-, 8.9-, and 11-cm] screens and tubing and 4-in. JPT P. 1035

Relative density measurements in a simple lung phantom by Compton backscatter

Compton backscatter of 60 keV γ radiation from a simple lung phantom has been used to measure changes in “lung” density. It was shown how introduction of a small volume of air can increase as well as decrease the count. Radiation scattered from the “chest wall” was prevented from entering the detector by careful choice of geometry. The remaining count increased linearly with “lung” density. The relative increase of count rate with density was entirely independent of “chest wall” thickness. With our apparatus a change of 0.01 kg/L in “lung” density produced a change in count rate of 2.2%.

A Proton-Recoil Proportional-Counter Array for Neutron-Image Construction

The fuel-motion measurement capability of the fast-neutron hodoscope has been upgraded by the addition of a 360-detector proton-recoil proportional-counter array, which detects high-energy fission neutrons. The current sensitive amplifier/discriminator module for each detector fits into a 12.7- by 12.7- by 102-mm package and costs less than $100 per module. It has a 50-ns rise time, a noise level of 100 nA, and a deadtime per event of 200 ns. Provision has been provided for the independent adjustment of the input current versus discriminator voltage for each module. The new proportional-counters cost approximately $400 each. Each detector has been tested to have the same gain versus voltage response. A space-charge model relating count-rate changes to space-charge effects has also been developed. The new detector array has been operational for approximately two years and has become the main detector system in fuel-motion analysis. It has significantly improved the linearity, stability, count-rate capability, and setup ease of the hodoscope.

Venous occlusive RN plethysmography: Comparison with electrical admittance plethysmography

A venous occlusion plethysmography using radionuclide(RN) was introduced for the measurement of the limb blood flow. This technique, called RN plethysmography, can be carried out in a subject who has been previously administered RN intravenously for the routine angiographic examination. The blood flow is calculated from the initial slope of the RN count rate change (RN accumulation curve) due to venous occlusion. In this study, this method was compared with electrical admittance plethysmography. The blood flow values determined by these two methods correlated well with each other.

Search for a neutron electric dipole moment

A magnetic resonance spectrometer in which ultra-cold neutrons are stored for 60 s to give a resonance width of 0.008 Hz has been used to search for a neutron electric dipole moment (EDM) by observing the change of count rate when an aligned electric field is periodically reversed relative to a magnetic field. The measured neutron EDM is (+0.3 ± 4.8) × 10 −25 e cm.

Energy discriminant coincidence detection as a possible aid to improved performance in airborne radiation detectors

The possibility of using a pair of detectors acting in coincidence to provide a compton spectrometer and thereby allow directional detection of radiation without shielding is described. The directional property of the concept relies on the detection of photons which are backscattered by one of the detectors. The possible use of the concept to enhance photopeak spectra is also examined. Low count efficiency rules out the generation of well resolved compton spectra in an aircraft but the change of count rate in the compton channel appears to provide for a practical real time monitor for the direction of radiation sources which generate significant anomalies in the normal photopeak spectrum.

Determination of photopeak energy in instrumental neutron activation analysis

The precision and accuracy of the peak energy allocation in γ-ray spectrometry govern the subsequent computer processing of the data. By applying the main procedures for peak energy determination to a well-defined case, it is possible to define the minimal statistical uncertainties to be expected. The systematic bias of the energies obtained is caused mainly by changes in the total count rate. A correction can be applied based on the pulser peak. From the precision and the accuracy of the peak energy determination, the scanning width for automatic peak indexing follows.

Liquid scintillation counter stability

Measurement of the count rate stability of 22 liquid scintillation counters are presented using standard gamma and neutron sources, the latter with PSD applied against gammas. Each detector system is nominally identical and no explicit method of gain stabilisation is incorporated. Large fluctuations between individual detector performances are noted in the gamma measurement, the best showing count rate fluctuation within Poisson uncertainties, the worst showing substantial time dependent effects. Changes in detector orientation also produce noticeable count rate changes in some cases. Simultaneous measurements of temperature and mains voltage fail to account for count rate variation.

Radionuclide evaluation of peripheral circulatory dynamics: New clinical application of blood pool scintigraphy for measuring limb venous volume, capacity, and blood flow

A new application of clinical blood pool imaging is described for measurements of limb venous volume and blood flow. Forearm count rate changes determined using blood pool imaging of in vivo Tc-99m labelled red blood cell (RBC) were compared in the same limb to forearm volume changes measured by Whitney mercury-in-silicone rubber strain gauge in eight normal subjects. Intravascular count rate changes closely correlated with volume changes following sudden (mean r = 0.98) and stepwise (mean r = 0.96) limb venous congestion for assessment of venous compliance, as well as for measurement of limb blood flow up to 20 ml/min/100 ml (r = 0.95). These results indicate the accuracy and utility of the radionuclide technique in the study of peripheral circulatory dynamics in clinical settings. In addition, limb tissue fluid accumultion may also be quantified by simultaneous use of radionuclide-strain gauge plethysmography.

Time dependence of rate-dependent photomultiplier gain and its implications

Time dependences of rate-dependent photomultiplier gain were measured precisely in two particular tubes for various count rate changes. Most of the measured time dependences are shown to be well described by three exponential components. While the corresponding time constants remain unchanged for different count rate changes except the one of the first component, the relative population of each component varies considerably according to duration of the measurement immediately before the count rate change. Since the time dependence is considered to reflect the charge buildup on the dynode, a charge buildup model based on electron and hole trapping is proposed to explain the measured time dependences. An abrupt rise or fall in gain, which is clearly seen immediately after a count rate change, is interpreted as a manifestation of a large difference in value between the detrapping constants for trapped electrons and holes. It is shown that in order to be consistent with the measured time dependences the observed tendency of trapped holes to settle into deeper levels at larger times should be attributed to physical processes similar to those of polaron hopping. The proposed charge buildup model should not only indicate possible factors affecting the time dependence, but also give an insight into the physical mechanism involved in charge buildup on thin oxide films.