Mean Pulse Height Research Articles

DETERMINING MITRAL STENOSIS THROUGH RADIAL ARTERIAL PULSE: A COMPUTATIONAL UNDERSTANDING

Mitral Stenosis (MS) is an abnormal condition of the heart mitral valve in which the valve orifice area is reduced leading to many complications in heart function. Noninvasive and less expensive procedures for diagnosis are not currently available. The aim of this work was to explore the use of the radial artery pulse (RAP) to diagnose MS. This paper analyzed the effect of the development and growth of MS on possible radial artery noninvasive assessment parameters. For this, MS was introduced to ex vivo by varying the orifice area to either 1, 2, 3, 4 or 5[Formula: see text]cm2 in a hybrid cardiopulmonary electrical analogous model based on clinically obtained healthy controls with an orifice area of 6[Formula: see text]cm2. Results showed that a mitral valve area less than 2[Formula: see text]cm2 significantly influenced the pulse magnitude and time parameters. A strong correlation was observed in pulse height (PH), mean pulse height (MPH), and time occurrence of the dichotic notch. This may be due to increased blood remaining in the left atrium and hence decreased stoke volume (SV). SV is proportional to arterial pulse pressure which is evident from the decrease in the PH and MPH in MS. In summary, this study provides the first evidence that MS may be diagnosed by examining peripheral pulses which thus, needs further investigation to use RAP as a noninvasive and less expensive MS diagnostic tool.

Oxytocin secretion is pulsatile in men and is related to social-emotional functioning

The hypothalamic hormone oxytocin (OXT) plays an important role in a range of physiological processes and social-emotional functioning in both sexes. In women, physiological stimuli, such as suckling and parturition, result in pulsatile release of OXT into the peripheral circulation via the posterior pituitary gland. However, data regarding OXT secretory patterns in men during a state of rest are limited. Further, the relationship between secretory dynamics of OXT and emotional measures has never been evaluated. We hypothesized a pulsatile pattern of OXT secretion in men, and explored the relationship between OXT secretory patterns and social-emotional functioning. MethodsDeconvolution analysis was performed on serum OXT levels obtained every 5min over a period of 10h in 5 healthy normal weight men. Area under the curve (AUC), average OXT values, and pulse characteristics [pulse number, inter-pulse interval, pulse height and mass (area under each pulse)] were calculated. State Adult Attachment Measure (SAAM) assessed types of human attachment. Interpersonal Support Evaluation List (ISEL) assessed perception of social support. Toronto Alexithymia Scale (TAS-20) measured the ability to express and identify one’s own emotions. ResultsMean age was 22.8±1.2years, and BMI was 21.7±0.4kg/m2 (mean±SEM). Assuming a basal secretion of zero and a half life of five to seven minutes, we demonstrated the following: OXT AUC: 5421±1331pg/ml, mean OXT level: 9.1pg/ml, mean pulse number: 22±3/10hr, mean pulse height: 1.81±0.48pg/ml, mean pulse mass: 30.34±10.29pg/ml and mean inter-pulse interval: 27±4min. The SAAM Avoidant scale correlated negatively with mean OXT pulse height (r=−0.90, p=0.04) and pulse mass (r=−0.95, p=0.01). The ISEL Belonging score correlated positively with OXT AUC (r=0.89, p=0.04) and average OXT (r=0.93, p=0.02). ISEL Appraisal score also had a positive association with mean OXT pulse height (r=0.99, p=0.0006) and pulse mass (r=0.98, p=0.003). Finally, ISEL total score had a significant correlation with average OXT values (r=0.90, p=0.04). While none of the subjects had a score in the alexithymia range, TAS-20 Difficulty describing feelings score had an inverse correlation with OXT pulse height (r=−0.96, p=0.01) and pulse mass (r=−0.99, p=0.001). TAS-20 total score also had an inverse correlation with OXT pulse height (r=−0.94, p=0.02) and pulse mass (r=−0.96, p=0.009). ConclusionWe demonstrate a pulsatile pattern of peripheral OXT secretion in healthy men at rest. Subjects with lower OXT pulse height and pulse mass had a more avoidant style of attachment, felt less supported, and expressed greater difficulty in describing their feelings. Our findings support the concept that OXT is a key mediator of social-emotional functioning. Future studies to determine causality are warranted.

Investigation of 4H-SiC Schottky diodes by ion and X-ray micro beam induced charge collection techniques

Silicon carbide has recently emerged as an attractive material for ionisation radiation detection. The high band gap and high radiation damage resistance should allow the fabrication of detectors capable to operate at high temperature and in high radiation fields. The development of SiC radiation detectors in the field of spectroscopy imposes severe constraints in the electronic quality and homogeneity of the material. In this work we present an investigation of the charge collection properties of ‘detector grade’ 4H-SiC Schottky diodes performed by means of the X-ray and ion beam induced charge collection (XBICC and IBIC) techniques. Such techniques allow the minority carrier diffusion length of the material to be evaluated and mapping of the transport properties to be performed with a spatial resolution of the order of 1 μm. The investigated detectors are formed by Schottky contact (Au) on the epitaxial layer and an ohmic contact on the back side of 4H-SiC substrates. IBIC measurements were performed using protons of energy 0.7–1.7 MeV. The IBIC spectra show a complete charge collection generated by ionisation in the depletion region. Similar analysis was also performed in steady state conditions using data from photocurrent measurements carried out at European Synchrotron Radiation Facility using 3 keV photons. IBIC and XBICC maps were obtained by recording the mean pulse height and the mean photocurrent as a function of the photon or ion impact co-ordinates. The analysis of such maps allowed us to individuate the spatial distribution of defects and contact imperfections.

The growth hormone (GH)-releasing hormone-GH-insulin-like growth factor-1 axis in patients with fibromyalgia syndrome.

Fibromyalgia (FM) is a painful syndrome of nonarticular origin, characterized by fatigue and widespread musculoskeletal pain, tiredness, and sleep disturbances, without any other objective findings on examination. Interestingly, some of the clinical features of FM resemble the ones described in the adult GH-deficiency syndrome. Furthermore, insulin-like growth factor (IGF)-1 levels are frequently reduced in patients with FM. To gain further insight into the mechanisms leading to dysregulation of the GH-IGF-1 axis in these patients, we assessed 24-h spontaneous GH secretion, GH responses to GHRH, and IGF-1 and IGF binding protein (BP)-3 levels before and after 4 days treatment with human (h)GH. We found that, in comparison with controls, patients with FM exhibited a marked decrease in spontaneous GH secretion as assessed by mean GH secretion (2.5 +/- 0.4 microg/L in controls vs. 1.2 +/- 0.1 microg/L in FM, P < 0.05), pulse height (4.7 +/- 0.8 microg/L in controls vs. 2.5 +/- 0.3 microg/L in FM, P < 0.05), and pulse area (4.7 +/- 1 min/mg x L in controls vs. 2.3 +/- 0.3 min/mg x L in FM, P < 0.05). In contrast, GH responses to GHRH (100 microg, i.v.) were similar in controls (mean peak, 13.5 +/- 2.5 microg/L) and in patients with FM (12.2 +/- 3 microg/L). Finally, treatment with hGH (2 IU, s.c. daily), over 4 days, led to a clear-cut increase in plasma IGF-1 and IGFBP-3 levels in patients with FM. In conclusion, our data show that patients with FM exhibited a marked decrease in spontaneous GH secretion, but normal pituitary responsiveness to exogenously administered GHRH, thus suggesting the existence of an alteration at the hypothalamic level in the neuroendocrine control of GH in these patients. Furthermore, our finding of increased IGF-1 and IGFBP-3 levels after GH treatment, over 4 days, opens up the possibility of testing the therapeutic potential of hGH in patients with FM.

Preservation of growth hormone pulsatility despite pituitary pathology, surgery, and irradiation.

Detailed assessment of physiological and pathophysiological GH secretion has, until recently, been limited by the poor sensitivity of the available assays. We have used an ultrasensitive chemiluminescence GH assay (sensitivity, 0.002 microgram/L) to study 24-h GH profiles (20-min sampling) from 24 patients who had been treated for hypothalamic-pituitary disease with surgery and irradiation and from 24 healthy control subjects matched for age, sex, and body mass index. Twenty-three of the 24 patients demonstrated pulsatile GH secretion, determined by Cluster. The median (range) area under the curve for GH, mean pulse area, mean pulse height, average valley mean level, and mean interpeak nadir were lower in the patients than in the controls [119.25 (7.273-843.600) vs. 968.539 (227.200-4625.000) min/microgram.L (P < 0.00001); 3.777 (0.288-30.850) vs. 61.390 (12.880-224.210) min/microgram.L (P < 0.00001), 0.107 (0.010-0.958) vs. 1.408 (0.368-5.050) micrograms/L (P < 0.00001), 0.074 (0.006-0.415) vs. 0.348 (0.048-2.350) microgram/L (P < 0.00001), and 0.066 (0.003-0.270) vs. 0.205 (0.021-1.838) microgram/L (P = 0.0004), respectively]. The median (range) number of pulses, mean pulse duration, and mean interval between pulses did not differ between the patients and controls [10 (4-15) vs. 10 (7-15; P = 0.36), 96.4 (68.0-220.0) vs. 104.0 (72.0-151.4) min (P = 0.65) and 128.0 (92.8-255.0) vs. 126.2 (90.0-180.0) min (P = 0.73), respectively]. The diurnal rhythm of GH secretion was present in the controls, but there was only limited evidence of residual diurnal rhythm in the patients. This study has demonstrated that GH secretion remains pulsatile in GH-deficient patients despite the mass effect of hypothalamic-pituitary pathology, pituitary surgery, and radiotherapy. With the development of potent GH secretagogues that are active orally, our findings may have important implications for the future management of GH-deficient subjects.

Duration of the oestrous cycle and changes in plasma hormone concentrations measured after an induced ovulation in scimitar‐horned oryx (Oryx dammah)

To determine the duration and hormonal characteristics of the oestrous cycle in scimitar‐horned oryx, ovulation was synchronized in 11 females using exogenous progesterone and a prostaglandin analogue. Daily blood samples were taken from six animals during 46 days (with a 7‐day hiatus). The remaining five animals were blood sampled every 30 min for 6 h on three occassions druing 22 days, then resynchronized with prostaglandin analogue and pregnant mare's serum gonadotrophin and blood sampled daily for another 21 days (with a 7‐day hiatus). Behavioural observations were made on days 1 through 3 and 24 through 28 to determine the occurrence of oestrus.Only animals &gt; 2 years old (n= 7) had plasma progesterone concentrations indicative of luteal function, with a mean luteal phase progesterone concentration of 13.6 ± 3.3 (S.E.) nmol.l−1 and a mean follicular phase concentration of &lt; 3.2 nmol.l−1. Mean duration of the oestrous cycle estimated from plasma progesterone profiles and behavioural data 22.7 ± 1.1 (S.E.; n= 7) days, range 17‐25 days. When estimated from behavioural data alone, mean duration of the oestrous cycle was 22.3 ± 0.3 (S.E.; n= 3) days, range 22‐23 days. Mean length of the luteal phase was 17.3 ± 0.6 (S.E.; n= 8) days, range 14‐19 days, and mean length of the follucular phase was 5.6 ± 0.5 (S.E.; n= 5) days, range 3‐7 days. Pulses in plasma LH concentration detected by Cluster analysis ranged from 0.34‐1.55ng.ml−1 in animals ≷ 2 years old (n= 3), and from 0.17‐0.29ng.ml−1 in animals &lt; 2 years old (n= 2), the difference in mean pulse height being significant (P &lt; 0.01). No difference in mean plasma LH concentration was detected due to stage of cycle. Elevations in plasma oestradiol‐17β concentration were observed at or preceding oestrus in three animals and during the mid‐luteal phase in three animals.A significant decrease in haematocrit with time was recorded for blood samples from the third serial bleed. This was greater (P &gt; 0.01) in animals &gt; 2 years of age (n= 3), suggesting that these older animals adapted better to the stress of repeated sampling. Plasma cortisol concentrations also declined throughout the serial bleed but there was no difference in this decline between the two age groups.Results of this study define the duration of the oestrous cycle in scimitar‐horned oryx and show that its hormonal components are similar to the well‐characterized patterns of other species, especially cattle.

Computer simulation of light emission by high-energy electrons in YAG single crystals

Elastic and inelastic multiple scattering in a thin yttrium aluminum garnet (YAG) single crystal attached on a glass plate has been calculated by a Monte Carlo method. The simulation has been made for several accelerating voltages ranging from 100 kV to 1 MV. Nearly all of the energy of 100–200 keV electrons is absorbed in the YAG crystal but high-energy electrons penetrate the crystal and are then scattered in the base glass. The absorbed energy in YAG crystal produces the light pulse which is converted into an electric pulse by a photomultiplier and amplifiers. The distribution of the pulse height and the mean pulse height are calculated from the total light emission by individual electrons. Some of the backscattered electrons stimulate the YAG crystal but the scintillation light of this contribution is not large. The spatial distribution of the electron beam spread in the crystal is also determined. The comparison of the calculational results with experiments shows that the simulation gives a good representation of scintillator properties.

Characteristics of the radiation damage seen in the silicon microstrip detector of Fermilab experiment E771

The central region of the silicon microstrip detector used in Fermilab experiment E771 was subjected to a peak fluence of 9.5 × 10 13 p/cm 2 induced by 800 GeV protons over a two-month period. Fourteen 300 μm thick planes manufactured by Micron Semiconductor were operated at bias voltages ranging from 84 to 109 V. Analysis of data from low intensity beam triggers taken near the end of the run shows that the mean pulse height from our amplifiers began to decline at a fluence of approximately 2 × 10 13 p/cm 2 and fell to near zero by 6 × 10 13 p/cm 2. We show that the use of fast amplifiers contributed to this early loss of signal.

Pulsatility of 24-hour concentrations of circulating interleukin-1-alpha in healthy women: analysis of integrated basal levels, discrete pulse properties, and correlation with simultaneous interleukin-2 concentrations.

Even though it is widely known that interleukin (IL)-1 alpha acts at the local level, it is still uncertain whether IL-1 alpha is secreted into the circulation and acts at distant sites. We have tried to elucidate this by measuring 24-hour levels of total IL-1 alpha in six healthy female volunteers. Subjects had detectable and pulsatile levels of IL-1 alpha throughout the 24-hour period. The integrated 24-hour IL-1 alpha concentration was 2,367 +/- 753 min x micrograms/l (mean +/- SD), and the integrated pulsatile IL-1 alpha concentration was 553 +/- 260 (25 +/- 10% ot total integrated IL-1 alpha). The mean IL-1 alpha concentration was 1.63 +/- 0.53 micrograms/l, mean pulse frequency/24 h was 12.8 +/- 0.8, mean pulse height was 2.31 +/- 0.52 micrograms/l; mean pulse width was 80.4 +/- 2.3 min, and mean interpulse interval was 105.3 +/- 2.8 min. Total IL-1 alpha levels significantly correlated with those previously reported for IL-2 in the same samples, and IL-1 alpha pulse parameters which are concentration independent were significantly similar to those of IL-2. Furthermore, cross-correlation analysis indicated that in 83% of our subjects (5/6) there was synchronicity of IL-1 alpha and IL-2 levels. IL-1 alpha pulse parameters were in the range reported for hormones which have well-characterized pulsatility, such as growth hormone, luteinizing hormone, follicle-stimulating hormone, cortisol, beta-endorphin, and progesterone. Based on these data we speculate that a pulsatile cytokine cascade may exist in the systemic circulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Pulsatile Thyrotropin Release and Thyroid Function in Acromegalics before and during Subcutaneous Octreotide Infusion*

The pulsatile secretion of TSH was studied in eight patients with active acromegaly before treatment and after 1 month of therapy consisting of the sc infusion of 300 micrograms octreotide/day. Mean GH levels decreased from 37.1 +/- 7.2 to 5.2 +/- 1.4 mU/L (P = 0.002). Insulin-like growth factor-I levels decreased from 82.9 +/- 8.8 to 37.8 +/- 9.8 nmol/L (P less than 0.01) and normalized in five of the eight patients. In one patient TSH levels were undetectable before and during octreotide therapy. In the other seven patients, Cluster analysis revealed 11.9 +/- 0.8 pulses/24 h, with a mean pulse width of 81 +/- 4.6 min, a mean pulse height of 1.33 +/- 0.42 mU/L, and a mean pulse increment of 0.36 +/- 0.12 mU/L. During octreotide therapy these pulse parameters remained unchanged. Pulse height and amplitude increased significantly during the night (i.e. from 2000-0800 h) in both untreated and treated patients. The acrophase was unchanged by therapy. During therapy T3 levels decreased from 2.05 +/- 0.17 nmol/L to 1.44 +/- 0.08 nmol/L (P = 0.001), while rT3 levels increased from 0.14 +/- 0.02 nmol/L to 0.19 +/- 0.03 nmol/L (P less than 0.05). Plasma T4 levels remained unchanged. From these studies we conclude that the TSH pulse generator is unchanged in active acromegaly and apparently unaffected by chronic octreotide infusions.

Computer-aided analysis of discharge patterns

In recent years investigations of the use of digital evaluation of partial discharges have become increasingly important. Such methods of evaluation greatly improve the recognition of discharge patterns and the correlation of these patterns with various types of defects. Conventional methods of oscillographic observation provide a limited recognition of defects causing discharges. A powerful interpretation of the discharge signals can be achieved when a large number of discharge quantities are measured simultaneously, making use of their stochastic character. A computer-aided discharge analyser has been built for continuous and multiparameter registration. This paper concentrates on the analysis of several parameters for recognizing patterns of partial discharges in a dielectric. A combination of statistical and discharge parameters was studied to discriminate between different types of cavities. Two phase-angle quantities, pulse counts and mean pulse height distributions as a function of phase angle, were processed, using different statistical operators such as skewness, kurtosis and modified cross correlation. The tests on samples with different internal defects have shown that significant differences exist in the behaviour of discharge parameters. Three of these parameters provide a good description of discharge and offer a good discrimination between different internal defects.

Age alters pulsatile prolactin release: influence of dopaminergic inhibition

To determine the effect of age on pulsatile prolactin secretion, we examined prolactin pulse characteristics by cluster analysis in healthy young and old male subjects during the day and night. Pulsatile prolactin secretion was identified in all subjects during the day and night, and prolactin pulse frequency remains stable with age. Younger subjects had a significantly higher prolactin pulse amplitude, area, and peak interval during the night compared with older subjects. In contrast, daytime prolactin pulse characteristics were similar in young and old subjects. Because the major neuroregulator of prolactin is dopamine and because normal aging has been reported to be associated with reductions in hypothalamic dopamine content and effect, we determined whether the mechanism of altered day-night prolactin pulsatile secretion was due to changes in dopaminergic tone. We examined endogenous prolactin secretion after administration of the dopamine antagonist metoclopramide. Metoclopramide significantly increased mean serum prolactin concentration and prolactin pulse height and amplitude in all subjects during the day and night. However, net prolactin pulse amplitude after metoclopramide stimulation at night was significantly higher in older subjects compared with younger subjects. We conclude that prolactin pulse amplitude is blunted in elderly men at night and that daytime pulsatile prolactin secretion is unaltered by age in normal men. The mechanism for this alteration of nighttime prolactin pulsatile secretion in elderly men may be due to age-associated changes in dopaminergic regulation.

Proportional counters as low energy photon detectors

We have investigated the response of an argon methane proportional counter to monochromatic X-rays in the range 99–277 eV. The apparent nonlinearities in mean pulse height as a function of photon energy and the detailed shape of the pulse height distribution for each energy can be predicted quite precisely using the extensive atomic data available for argon. Based on this understanding, we propose a semiempirical system for using a limited amount of calibration data to predict the full response of counters employing less well characterized gasses. Such accurate models of proportional counter response are required to maximize the spectral information that can be derived from observed pulse height distributions.

On the Calibration of Tissue-Equivalent Proportional Counters with Built-in Alpha Particle Sources

Abstract The calibration procedure for tissue-equivalent proportional counters (TEPC) with built-in collimated a sources was investigated. Pulse height spectra were measured for the a particle sources of several counters which were filled with propane based TE gas at various pressures in order to simulate a tissue layer thickness of 1 µm to 10 µm. The mean pulse height produced by unscattered a particles was determined relative to the maximum measured pulse height. These pulse height ratios were also calculated using tabulated stopping power data for a particles, the experimentally determined detector geometry and measured a source energies. The ratios obtained for various stopping power data are compared with the experimental values. Characteristic edges due to maximum energy losses of secondary protons and a particles over the finite cavity diameter also appear in neutron produced spectra. It is proposed to use the pulse heights related to maximum energy losses of charged particles in the detector cavity to examine the uncertainty of the conventional TEPC calibration techniques.

Nonlinear response of Si detectors for low-Z ions

We report measurements of the relative mean pulse height produced by 1H, 4He, 7Li and 16O ions in Si surface barrier detectors. The data are anomalous in that the pulse height for different ions of the same energy (after window and nonionizing losses are subtracted) increases with atomic number, contrary to observations for fission fragments. A simple model invoking a stopping power dependence of the energy required to create an electron-hole pair is consistent with all experimental data, suggesting that the response of Si detectors is nonlinear with particle energy.

Measurements of the response of a hadronic calorimeter to beams of pions and protons of 1–10 GeV/ c momenta

An ionization calorimeter was studied with a test beam at the Brookhaven Alternating Gradient Synchrotron. The purpose of the experiment was to calibrate the response of a similar but larger cross section calorimeter used to study high energy cosmic ray showers at the University of Maryland, College Park, Maryland. The beam momenta were between 1 and 10 GeV/ c. Results of measurements of (1) the mean pulse height from a scintillator at different depths in the calorimeter, (2) the frequency of occurrence of very rare events with pulse heights many times the mean pulse height and (3) the correlation of pulse heights from several scintillators at different depths are presented and discussed.

A thin detector with ionization tubes for high energy electrons and photons

The possibility of measuring the energy of electrons and photons with a simple detector consisting of a lead convertor and ionization tubes filled with pure argon has been studied. The measurements have been performed in a 26.6 GeV electron beam. The best energy resolution σ/E ∼ 16% was achieved for a convector thickness of 40 mm and an argon pressure ⪆20 atm.The performance of the detector in magnetic fields up to 16 kG has also been studied. It turned out that the mean pulse height rises approximately linearly with increasing magnetic field and becomes flat at H ∼ 10 kG. This behavior is the same for magnetic fields perpendicular and parallel with respect to the ionization tubes. The energy resolution depends weakly on the magnetic field.Ionization tubes filled with argon or xenon under high pressure may be used for minimum ionizing particle detection.

The performance of a gas scintillation counter at high count rates

Using a gas mixture of 10% N 2 in argon in a gas scintillation counter with a thick wire anode of 400 μm, the energy resolution and the mean pulse height from the photomultiplier were studied at rates up to 10 MHz. A shift of the pulse heigth o only 10% was measured for a rate of 6 MHz, with an energy resolution of 56% for 6.9 keV X-rays.

Secretion of luteinizing hormone in ovariectomized adult rats treated neonatally with monosodium glutamate.

We have studied the possible effects of monosodium glutamate (MSG) on LH secretion in ovariectomized rats. In experiment 1 MSG-treated and control rats were given oestradiol benzoate at noon and 72 h later half the rats in each group were given a second injection of oestradiol benzoate or progesterone. Blood samples were taken immediately before and 6 h after these i.m. injections. At 78 h there were no significant differences in plasma LH concentration measured in the two groups of rats given progesterone or in the two groups given a second injection of oestradiol benzoate although for both MSG-treated and control rats progesterone produced a significantly (P less than 0.01) greater LH surge than did oestradiol benzoate. In experiment 2 100 ul blood samples were collected at 5-min intervals for up to 3 h from MSG-treated and control rats. For rats showing more than one pulsatile discharge of LH, peak and trough values for plasma LH concentrations were no significantly influenced by MSG treatment. However the mean pulse height was significantly (P less than 0.001) greater in the MSG-treated group than in control rats. Pulsatile release stopped more quickly in the MSG-treated rats and their mean plasma LH concentration after 120 min of blood sampling was significantly (P less than 0.05) lower than that obtained in the control animals. Thus, although some aspects of LH secretion seem to be significantly different in MSG-treated rats, these effects may result from the greater sensitivity of the MSG-treated animals to experimental manipulation.

Die impulshöhenverteilung und das ansprechvermögen eines NaJ(TI)-szintillationsdetektors für monoenergetische röntgenstrahlen IM energiegebiet einiger keV

The pulse height distributions of a NaI(Tl)-scintillation detector for monoenergetic X-rays of a few keV were compared with the calculations of Prescott. Good agreement was achieved except for quantum-energies near the iodine-L-absorption-edges. In this region the relative variance of the distributions no longer showed a linear dependence on the reciprocal mean pulse height but a structure caused by the different absorption processes under and above the L-edges. A similar structure was observed in the response of the detector (mean pulse height/energy). This behaviour shows that the photon distribution in the scintillation crystal near the L-edges is strongly affected by the quantum energy and cannot be described by a Poisson distribution.