Suggested diagnostic reference levels for paediatric X-ray examinations in India

Exposure of children to ionising radiation is considered to carry higher risk than that of adults; therefore a need to suggest diagnostic reference levels (DRLs) for the common paediatric diagnostic X-ray procedures was recognised for the X-ray machines meeting the requirements of the recently implemented Safety Code for Medical Diagnostic X-ray Equipment and Installations in India. Measurements were carried out for entrance surface air kerma (free in air) in conventional paediatric X-ray diagnostic examinations among four age groups: <1, 1-4, 5-9 and 10-15 y. A total of 2240 air kerma measurements at different fixed focus to skin distances were studied for 7 paediatric diagnostic examinations with 11 different projections on 62 X-ray machines installed in 22 selected hospitals in the country. The third quartile values of air kerma per paediatric examination for the age group of 5-9 y were considered as values of paediatric DRLs. The suggested values of DRLs are 0.2 mGy for chest AP/PA, 0.3 mGy for chest LAT, 0.7 mGy for lumber spine AP, 1.3 mGy for lumber spine LAT, 0.3 mGy for thoracic spine AP, 0.6 mGy for thoracic spine LAT, 0.5 mGy for abdomen AP, 0.7 mGy for pelvis AP, 0.6 mGy for skull PA, 0.5 mGy for skull LAT and 0.8 mGy for hip joints AP.     

The insulation of freezers and refrigerators— how thick should it be?Isolation des réfrigérateurs et des congélateurs — quelle doit être son épaisseur?

Calculations are presented for the insulation losses for a range of sizes of domestic freezers and refrigerators with different insulation thicknesses. Power consumptions are also evaluated allowing for other losses, such as around doors, for a normal load pattern, and for compressor efficiencies. It is shown that the scope for power savings with increased insulation is only about 20% for freezers and 30% for refrigerators.     

Terrestrial gamma radioactivity levels and their corresponding extent exposure of environmental samples from Wadi El Assuity protective area, Assuit, Upper Egypt

Representative environmental samples (sandy soil, limestone, marble and gravels) collected from Wadi El Assuity, protective area, Assuit governorate in Upper Egypt have been investigated radiometrically using NaI (Tl) gamma-ray spectrometer. The specific activity of the radionuclides in Bq kg?1 for soil ranged between 10.5 and 18.7 for 22?Ra, 1.5 to 4.6 for 232Th and from 94 to 107 for ??K, for limestone ranged between 19 and 27.1 for 22?Ra, 32.9 to 50 for 232Th and from 49 to 7 3 for ??K, where, for marble ranged between 12.2 and 30.7 for 22?Ra, 32.6 to 59.5 for 232Th and 55 to 70 for ??K and for gravels ranged between 7.8 and 21.8 for 22?Ra, 19.8 to 30.0 for 232Th and from 151 to 260 for ??K. The mean activity concentrations of measured radionuclides were compared with other literature values. The absorbed dose rate, radium equivalent activity and external hazard index were calculated and compared with internationally recommended values. The gamma absorbed dose rates in the samples ranged between 8.44 and 50.89 nGy h?1. These dose rates are consistent with the accepted worldwide average 55 nGy h?1 for the public. All values obtained for radium equivalent activity are < 370 Bq kg?1, which are acceptable for safe use. The calculated values of external hazard index obtained varied from 0.12 to 0.24. Since these values are lower than unity, one can say that the radiation hazard is insignificant for the population living in the investigated area. This permits the use of these materials sediments as building materials in any probable development projects at this area.     

顶空气相色谱法测定盐酸法舒地尔中有机溶剂残留量

本文应用顶空进样方式,DB-624毛细管柱分离,FID检测器,外标法定量测定盐酸法舒地尔中乙醚,甲醇,二氯甲烷残留量,结果3个组分完全分离.分离度为甲醇,乙醚之间为19.0,乙醚和二氯甲烷之间为20.8.在所考察的线性范嗣内具有良好的线性关系,相关系数r分别为甲醇0.9993,乙醚为0.9997,二氯甲烷为0.9963...     

Occupational exposure to staff during endoscopic retrograde cholangiopancreatography in Sudan

Endoscopic retrograde cholangiopancreatography (ERCP) procedure is an invasive technique that requires fluoroscopic and radiographic exposure. The purpose of this study was to determine the occupational dose of ionising radiation at three gastroenterology departments (Fedial, Soba and Ibn seena hospitals) in Khartoum, Sudan. The radiation dose was measured during 55 therapeutic ERCP procedures. Thermoluminescence dosemeters were used. The mean radiation dose for the first operator was 0.27 mGy for the eye lens, 0.21 for the thyroid, 0.32 for the chest, 0.17 for the hand and 0.22 for the leg. The mean radiation dose for the second operator was 0.21 mGy for the hand and 0.20 mGy for the chest, while the mean radiation dose for the nurse was 0.44 mGy for the hand and 0.19 for the chest. The radiation dose received by the staff in these hospitals was found to be higher than most of the values in the literature. The radiation absorbed dose received by the different organs is relatively low. Additional studies need to be conducted for radiation dose optimisation.     

Patient skin dosimetry in haemodynamic and electrophysiology interventional cardiology

With the increase in number and complexity of interventional cardiology (IC) procedures, it is important to monitor skin dose in order to decrease skin injuries. This study investigated radiation doses for patients undergoing IC procedures, compare results with the literature and define a local dose-area product trigger level for operators to identify situations likely to exceed the threshold for transient skin erythema of 2 Gy. Dosimetric data were collected for 77 haemodynamic and 90 electrophysiological procedures. Mean maximum local skin doses (MSDs) were 0.28 Gy for coronary angiography, 1.03 Gy for percutaneous transluminal coronary angioplasty (PTCA), 0.03 Gy for pacemaker insertion, 0.17 Gy for radiofrequency ablation for nodal tachycardia, 0.10 Gy for WPW and 0.22 Gy for atrial flutter. Since MSD values for the other procedures were well below the deterministic effect limit, a trigger level of 140 Gy cm2 was derived for PTCA procedures alone.     

Air kerma to dose equivalent conversion coefficients not included in ISO 4037-3

The International Organization for Standardization (ISO) has issued a standard series on photon reference radiation qualities (ISO 4037). In this work, conversion coefficients from air kerma to dose equivalent quantities not included in ISO 4037-3 are supplied for the following quantities: For H(p)(0.07) for X and gamma radiation qualities for the rod, the pillar and the slab phantom and for H(p)(3) for X and gamma radiation qualities for the slab phantom. In addition, an overview of conversion coefficients suggested for use for all quantities relevant in radiation protection is provided.     

The insulation of freezers and refrigerators— how thick should it be?

Calculations are presented for the insulation losses for a range of sizes of domestic freezers and refrigerators with different insulation thicknesses. Power consumptions are also evaluated allowing for other losses, such as around doors, for a normal load pattern, and for compressor efficiencies. It is shown that the scope for power savings with increased insulation is only about 20% for freezers and 30% for refrigerators.     

Quantitative analysis of HIV-1 protease inhibitors in cell lysates using MALDI-FTICR mass spectrometry

In this report we explore the use of MALDI-FTICR mass spectrometry for the quantitative analysis of five HIV-1 protease inhibitors in cell lysates. 2,5-Dihydroxybenzoic acid (DHB) was used as the matrix. From a quantitative perspective, DHB is usually a poor matrix due to its poor shot-to-shot and poor spot-to-spot reproducibilities. We found that the quantitative precisions improved significantly when DMSO (dimethylsulfoxide) was added to the matrix solution. For lopinavir and ritonavir, currently the most frequently prescribed HIV-1 protease inhibitors, the signal-to-noise ratios improved significantly when potassium iodide was added to the matrix solution. The mean quantitative precisions, expressed as % relative standard deviation, were 6.4% for saquinavir, 7.3% for lopinavir, 8.5% for ritonavir, 11.1% for indinavir, and 7.2% for nelfinavir. The mean quantitative accuracies, expressed as % deviation, were 4.5% for saquinavir, 6.0% for lopinavir, 5.9% for ritonavir, 6.6% for indinavir, and 8.0% for nelfinavir. The concentrations measured for the individual quality control samples were all within 85-117% of the theoretical concentrations. The lower limits of quantification in cell lysates were 4 fmol/microL for saquinavir, 16 fmol/microL for lopinavir, 31 fmol/microL for ritonavir, and 100 fmol/microL for indinavir and nelfinavir. The mean mass accuracies for the protease inhibitors were 0.28 ppm using external calibration. Our results show that MALDI-FTICR mass spectrometry can be successfully used for precise, accurate, and selective quantitative analyses of HIV-1 protease inhibitors in cell lysates. In addition, the lower limits of quantification obtained allow clinical applications of the technique.     

Patient dose measurements in diagnostic radiology procedures in Montenegro

It was the aim of the study presented here to estimate for the first time patient dose levels in conventional diagnostic radiology in Montenegro. Measurements of patient dose in terms of entrance surface air kerma (ESAK) and kerma-area product (KAP) were performed on at least 10 patients for each examination type, in each of five randomly selected health institutions in Montenegro, so that a total of 872 patients for 16 different examination categories were included in the survey (817 patients for 1049 radiographies and 55 fluoroscopy patients). Exposure settings and individual data were recorded for each patient. Mean, median and third quartile values ESAK of patient doses are reported. The estimated mean ESAK values obtained are as follows: 4.7 mGy for pelvis anteroposterior (AP), 4.5 mGy for lumbar spine AP, 7.8 mGy for lumbar spine lateral (LAT), 3.1 mGy for thoracic spine AP and 4.3 mGy for thoracic spine LAT. When compared with the European diagnostic reference values, the mean ESAK for all studied examination types are found to be below the reference levels, except in chest radiography. Mean ESAK values for chest radiography are 0.9 mGy for posteroanterior (PA) projection and 2.0 mGy for LAT. The results exhibit a wide range of variation. For fluoroscopy examinations, the total KAP was measured. The mean KAP value per procedure for barium meal is found to be 22 Gy cm(2), 41 Gy cm(2) for barium enema and 19 Gy cm(2) for intravenous urography. Broad dose ranges for the same types of examinations indicate the necessity of applying practice optimisation in diagnostic radiology and establishment of national diagnostic reference levels.     

Implications of optical properties of ocean, lake, and ice for ultrahigh-energy neutrino detection

The collecting power and imaging ability of planned ultrahigh-energy neutrino observatories depend on wavelength-dependent absorption and scattering coefficients for the detector medium. Published data are compiled for deep ice at the South Pole, for deep fresh water at Lake Baikal, and for deep seawater. The effective scattering coefficient is smallest for the clearest deep ocean sites, whereas the absorption coefficient is an order of magnitude smaller for deep ice than for the ocean and lake sites. The effective volume per detector element as a function of energy is calculated for electromagnetic cascades produced by electron neutrinos interacting at the various sites. It is largest for deep bubble-free ice, smallest for shallow bubbly ice, and intermediate for lake and seawater. The effective volume per element is calculated for detection of positrons resulting from the capture of a few megaelectron volt supernova neutrinos by protons in the medium. This volume is proportional to the absorption length and independent of the scattering length; it is larger for ice than for seawater or lake water.     

Mechanical reliability,how do we advance?

The development of theory and practice for electronic and mechanical reliability is described, and mechanical reliability is seen to be lagging in practice. Theory and practice are described for a project from conception to market feedback for mechanical as well as for electronic reliability. It is noted that for each phase theoretical and practical methods exist for mechanical as well as for electronic reliability analysis. Activities are listed which can strengthen mechanical reliability theory and practice.     

LRZ-4型微机自控连续乳化炸药生产线技术的研究及应用

文章介绍了LRZ－4型微机自控连续乳化炸药生产线的工艺,自控系统的设计,关键设备的研制及生产线的应用,并在此基础上详细阐述了该生产线所具备的安全,质量保障体系及独特的工艺技术。     

Efficient multi-user detection scheme for overloaded group-orthogonal MC-CDMA systems

An efficient multi-user detection scheme for overloaded MC-CDMA systems is presented. The proposed detection scheme for overloaded systems achieves the optimal performance for constant-modulus modulation schemes, for example MPSK, and provides near-optimal performance for non-constant-modulus modulation, for example M-QAM. Moreover, it has overall lower complexity than the other optimal detection algorithms, especially suitable for group-orthogonal MC-CDMA systems, where group-based technique keeps multi-user receiver size relatively small.     

Schichten über Schichten

Films over films: innovative coatings for complex applications Thin films and coatings have developed as a prerequisite for many technical applications. In this paper, some applications for electrical, electronic, biomedical and optical applications are presented. In this contribution, examples for coatings for conductive and transparent films in photovoltaics, films for biomedical electrodes, for semiconductor contacts and for high‐temperature contacts are presented and discussed. The films are prepared by magnetron‐sputtering and pulsed laser deposition. The influence of the processing parameters on the functional properties of the films is presented.     

Approximating the risk for time-to-failure models through using statistics of extremes

This paper studies the approximation of the partitioned multiobjective risk method's (PMRM) extreme event risk function for time-to-failure models. The analytic expression of the approximation for the extreme event risk function is derived through the use of the statistics of extremes for the case where the underlying distribution is of an extreme-value type III for minima. This analytic expression provides an effective theoretical tool for understanding the behavior of conditional expected values for time-to-failure models for a large class of distribution functions used in reliability. The results are confirmed for example problems of exponential and uniform distributions.     

Tuning Optimization for Second-Order Dynamic Filters for Random Signal Spectral Analysis

Initial formulas are derived for the spectral window of a narrow-band second-order dynamic filter and for the relative dispersion of the estimator for the spectral power density as measured by the correlation filter method, together with the general expression for the optimum tuning law for the filter damping coefficient for linear variation in the central frequency within the analysis band.     

Calculating sensor measurement ranges from structural and parametric models

Formulas are given for the absolute value of the measurement range for a technical device and the actual measurement range for the monitored quantity for computer-synthesized physical principles for the action of detector elements and new technical solutions, together with estimated parameters. Those parameters allow one to derive the necessary structural generalized techniques for attaining the required values.     

Amplitude-squared and amplitude-cubed squeezing in stimulated Raman and in spontaneous Raman scattering

Coherent light coupled to a third-order nonlinear medium is responsible for spontaneous and for stimulated Raman processes. The analytical solutions up to second order in coupling constants of various field modes for spontaneous Raman and for stimulated Raman processes are utilized to obtain the amplitude-squared and amplitude-cubed squeezing of the input coherent light. The amplitude-squared and amplitude-cubed squeezing are completely ruled out for all modes for spontaneous Raman processes. For stimulated Raman processes, we observe that the squeezing for amplitude-squared and amplitude-cubed are possible for pump and for vibrational phonon modes. It is found that the percentage of higher ordered amplitude squeezing decreases with the increase of the orders. The squeezing in Stokes and in anti-Stokes modes are ruled out even for stimulated Raman processes.