Evaluation of bias and variance in low-count OSEM list mode reconstruction

International Nuclear Information System (INIS)

Jian, Y; Carson, R E; Planeta, B

2015-01-01

Statistical algorithms have been widely used in PET image reconstruction. The maximum likelihood expectation maximization reconstruction has been shown to produce bias in applications where images are reconstructed from a relatively small number of counts. In this study, image bias and variability in low-count OSEM reconstruction are investigated on images reconstructed with MOLAR (motion-compensation OSEM list-mode algorithm for resolution-recovery reconstruction) platform. A human brain ([ 11 C]AFM) and a NEMA phantom are used in the simulation and real experiments respectively, for the HRRT and Biograph mCT. Image reconstructions were repeated with different combinations of subsets and iterations. Regions of interest were defined on low-activity and high-activity regions to evaluate the bias and noise at matched effective iteration numbers (iterations × subsets). Minimal negative biases and no positive biases were found at moderate count levels and less than 5% negative bias was found using extremely low levels of counts (0.2 M NEC). At any given count level, other factors, such as subset numbers and frame-based scatter correction may introduce small biases (1–5%) in the reconstructed images. The observed bias was substantially lower than that reported in the literature, perhaps due to the use of point spread function and/or other implementation methods in MOLAR. (paper)

The statistical interpretations of counting data from measurements of low-level radioactivity

International Nuclear Information System (INIS)

Donn, J.J.; Wolke, R.L.

1977-01-01

The statistical model appropriate to measurements of low-level or background-dominant radioactivity is examined and the derived relationships are applied to two practical problems involving hypothesis testing: 'Does the sample exhibit a net activity above background' and 'Is the activity of the sample below some preselected limit'. In each of these cases, the appropriate decision rule is formulated, procedures are developed for estimating the preset count which is necessary to achieve a desired probability of detection, and a specific sequence of operations is provided for the worker in the field. (author)

Maximum entropy deconvolution of low count nuclear medicine images

International Nuclear Information System (INIS)

McGrath, D.M.

1998-12-01

Maximum entropy is applied to the problem of deconvolving nuclear medicine images, with special consideration for very low count data. The physics of the formation of scintigraphic images is described, illustrating the phenomena which degrade planar estimates of the tracer distribution. Various techniques which are used to restore these images are reviewed, outlining the relative merits of each. The development and theoretical justification of maximum entropy as an image processing technique is discussed. Maximum entropy is then applied to the problem of planar deconvolution, highlighting the question of the choice of error parameters for low count data. A novel iterative version of the algorithm is suggested which allows the errors to be estimated from the predicted Poisson mean values. This method is shown to produce the exact results predicted by combining Poisson statistics and a Bayesian interpretation of the maximum entropy approach. A facility for total count preservation has also been incorporated, leading to improved quantification. In order to evaluate this iterative maximum entropy technique, two comparable methods, Wiener filtering and a novel Bayesian maximum likelihood expectation maximisation technique, were implemented. The comparison of results obtained indicated that this maximum entropy approach may produce equivalent or better measures of image quality than the compared methods, depending upon the accuracy of the system model used. The novel Bayesian maximum likelihood expectation maximisation technique was shown to be preferable over many existing maximum a posteriori methods due to its simplicity of implementation. A single parameter is required to define the Bayesian prior, which suppresses noise in the solution and may reduce the processing time substantially. Finally, maximum entropy deconvolution was applied as a pre-processing step in single photon emission computed tomography reconstruction of low count data. Higher contrast results were

Estimation of low level gross alpha activities in the radioactive effluent using liquid scintillation counting technique

International Nuclear Information System (INIS)

Bhade, Sonali P.D.; Johnson, Bella E.; Singh, Sanjay; Babu, D.A.R.

2012-01-01

A technique has been developed for simultaneous measurement of gross alpha and gross beta activity concentration in low level liquid effluent samples in presence of higher activity concentrations of tritium. For this purpose, alpha beta discriminating Pulse Shape Analysis Liquid Scintillation Counting (LSC) technique was used. Main advantages of this technique are easy sample preparation, rapid measurement and higher sensitivity. The calibration methodology for Quantulus1220 LSC based on PSA technique using 241 Am and 90 Sr/ 90 Y as alpha and beta standards respectively was described in detail. LSC technique was validated by measuring alpha and beta activity concentrations in test samples with known amount of 241 Am and 90 Sr/ 90 Y activities spiked in distilled water. The results obtained by LSC technique were compared with conventional planchet counting methods such as ZnS(Ag) and end window GM detectors. The gross alpha and gross beta activity concentrations in spiked samples, obtained by LSC technique were found to be within ±5% of the reference values. (author)

Particle count monitoring of reverse osmosis water treatment for removal of low-level radionuclides

International Nuclear Information System (INIS)

Moritz, E.J.; Hoffman, C.R.; Hergert, T.R.

1995-01-01

Laser diode particle counting technology and analytical measurements were used to evaluate a pilot-scale reverse osmosis (RO) water treatment system for removal of particulate matter and sub-picocurie low-level radionuclides. Stormwater mixed with Waste Water Treatment Plant (WWTP) effluent from the Rocky Flats Environmental Technology Site (RFETS), formerly a Department of Energy (DOE) nuclear weapons production facility, were treated. No chemical pretreatment of the water was utilized during this study. The treatment system was staged as follows: multimedia filtration, granular activated carbon adsorption, hollow tube ultrafiltration, and reverse osmosis membrane filtration. Various recovery rates and two RO membrane models were tested. Analytical measurements included total suspended solids (TSS), total dissolved solids (TDS), gross alpha (α) and gross beta (β) activity, uranium isotopes 233/234 U and 238 U, plutonium 239/240 Pu, and americium 241 Am. Particle measurement between 1--150 microns (μ) included differential particle counts (DPC), and total particle counts (TPC) before and after treatment at various sampling points throughout the test. Performance testing showed this treatment system produced a high quality effluent in clarity and purity. Compared to raw water levels, TSS was reduced to below detection of 5 milligrams per liter (mg/L) and TDS reduced by 98%. Gross α was essentially removed 100%, and gross β was reduced an average of 94%. Uranium activity was reduced by 99%. TPC between 1-150μ were reduced by an average 99.8% to less than 1,000 counts per milliliter (mL), similar in purity to a good drinking water treatment plant. Raw water levels of 239/240 Pu and 241 Am were below reliable quantitation limits and thus no removal efficiencies could be determined for these species

Survey on the presence of 90Sr in milk samples by a validated ultra low level liquid scintillation counting (LSC method

Directory of Open Access Journals (Sweden)

dell’Oro D.

2013-04-01

Full Text Available 90Sr is one of the most biologically hazardous radionuclides produced in nuclear fission processes and decays emitting high-energy beta particles turning 90Y. 90Sr is transferred from soil-plant to cow’s milk and then to humans if it is introduced into the environment. Radiostrontium is chemically similar to calcium entering the human body through several food chains and depositing in bone and blood-forming tissue (bone marrow. Among main foodstuffs assumed in human diet, milk is considered of special interest for radiostrontium determination, especially in emergency situations, because the consumption of contaminated milk is the main source of internal radiation exposure, particularly for infants. In this work an analytical method for the determination of radiostrontium in milk was developed and validated in order to determine low activity levels by liquid scintillation counting (LSC after achieving 90Y secular equilibrium condition. The analytical procedure was applied both in surveillance and routine programmes to detect radiocontamination in cow’s, goat and sheep milk samples.

Hybrid statistics-simulations based method for atom-counting from ADF STEM images

Energy Technology Data Exchange (ETDEWEB)

De wael, Annelies, E-mail: annelies.dewael@uantwerpen.be [Electron Microscopy for Materials Science (EMAT), University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp (Belgium); De Backer, Annick [Electron Microscopy for Materials Science (EMAT), University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp (Belgium); Jones, Lewys; Nellist, Peter D. [Department of Materials, University of Oxford, Parks Road, OX1 3PH Oxford (United Kingdom); Van Aert, Sandra, E-mail: sandra.vanaert@uantwerpen.be [Electron Microscopy for Materials Science (EMAT), University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp (Belgium)

2017-06-15

A hybrid statistics-simulations based method for atom-counting from annular dark field scanning transmission electron microscopy (ADF STEM) images of monotype crystalline nanostructures is presented. Different atom-counting methods already exist for model-like systems. However, the increasing relevance of radiation damage in the study of nanostructures demands a method that allows atom-counting from low dose images with a low signal-to-noise ratio. Therefore, the hybrid method directly includes prior knowledge from image simulations into the existing statistics-based method for atom-counting, and accounts in this manner for possible discrepancies between actual and simulated experimental conditions. It is shown by means of simulations and experiments that this hybrid method outperforms the statistics-based method, especially for low electron doses and small nanoparticles. The analysis of a simulated low dose image of a small nanoparticle suggests that this method allows for far more reliable quantitative analysis of beam-sensitive materials. - Highlights: • A hybrid method for atom-counting from ADF STEM images is introduced. • Image simulations are incorporated into a statistical framework in a reliable manner. • Limits of the existing methods for atom-counting are far exceeded. • Reliable counting results from an experimental low dose image are obtained. • Progress towards reliable quantitative analysis of beam-sensitive materials is made.

A 'delayed' counting method to determine indoor Rn-222 levels indirectly

CERN Document Server

Iannopollo, V; Trimarchi, M; Tripepi, M G; Vermiglio, G

2001-01-01

A new indirect and 'delayed' way is presented to determine indoor concentration of Rn-222 by best-fitting methods. If a rapid knowledge of Rn-222 levels is required and if a detection system is not available in situ, it is possible to obtain concentration of radioactive gas by determining of 'delayed' counts of Po-214. The 'delay' time consists of two or three hours. The method is based on the use of cellulose filters for particulate collection and on the analysis of samples by alpha spectroscopy. It is also possible to obtain concentrations of short-lived radon daughters Po-218, Pb-214, Bi-214, which are very important quantities in a medical framework.

Hybrid statistics-simulations based method for atom-counting from ADF STEM images.

Science.gov (United States)

De Wael, Annelies; De Backer, Annick; Jones, Lewys; Nellist, Peter D; Van Aert, Sandra

2017-06-01

A hybrid statistics-simulations based method for atom-counting from annular dark field scanning transmission electron microscopy (ADF STEM) images of monotype crystalline nanostructures is presented. Different atom-counting methods already exist for model-like systems. However, the increasing relevance of radiation damage in the study of nanostructures demands a method that allows atom-counting from low dose images with a low signal-to-noise ratio. Therefore, the hybrid method directly includes prior knowledge from image simulations into the existing statistics-based method for atom-counting, and accounts in this manner for possible discrepancies between actual and simulated experimental conditions. It is shown by means of simulations and experiments that this hybrid method outperforms the statistics-based method, especially for low electron doses and small nanoparticles. The analysis of a simulated low dose image of a small nanoparticle suggests that this method allows for far more reliable quantitative analysis of beam-sensitive materials. Copyright © 2017 Elsevier B.V. All rights reserved.

Ion counting method and it's operational characteristics in gas chromatography-mass spectrometry

International Nuclear Information System (INIS)

Fujii, Toshihiro

1976-01-01

Ion counting method with continuous channel electron multiplier which affords the direct detection of very small ion currents and it's operational characteristics were studied in gas chromatography-mass spectrometry. Then this method was applied to the single ion detection technique of GC-MS. A detection limit was measured, using various standard samples of low level concentration. (auth.)

Low-level flow counting of liquid chromatography column eluates

International Nuclear Information System (INIS)

Harding, N.G.L.; Farid, Y.; Stewart, M.J.

1982-01-01

The principal parameters which determine the operation of a high-resolution, high-sensitivity radioactive flow monitor are described: a) Sample preparation to ensure adequate recovery of radiolabelled sample, metabolites and internal standard. b) The instrument background count rate, when no sample or radiolabel is present in the flow cell, is a function of shielding and a reduction in noise obtained with a coincidence time below one microsecond. c) The minimum detectable amount of label depends upon the machine background, HPLC eluent and scintillator flow, whether or not packed flow cells are used, flow cell geometry, and the scintillator used. d) Three types of flow cell have been designed to cover the majority of HPLC and isotope applications. e) The performance of solid and liquid scintillators. It is shown that an instrument has been designed taking account of these parameters. The resulting design satisfies present high sensitivity counting requirements and maintains the resolution of current HPLC procedures when detection is by simultaneous flow radioassay and by optical methods. (orig.)

Interpretation of low-level environmental radioactivity measurements

International Nuclear Information System (INIS)

Zeigler, C.C.

1982-01-01

Levels of radioactivity in the environment from worldwide fallout have decreased by about a factor of 10 since the early 1970's and many environmental concentrations are now less than the routine estimated lower limit of detection. To accurately represent these data and to assist in evaluating very low levels of radioactivity, each instrumental value with its statistical counting error should be reported. In some instances the background count of the instrument exceeds the sample count resulting in a value that is less than zero (a negative concentration). Evaluation of these negative numbers along with zero and positive concentrations over a suitable sample population can yield important information about concentrations that are less than routine minimum levels of detection. Actual instrumental values (negative, zero and positive) with associated statistical counting errors have been reported by the Environmental Monitoring Group at the Savannah River Plant since 1977. Methods for evaluating these data are discussed and empirical data presented to illustrate important points

Serum Copper Level Significantly Influences Platelet Count, Lymphocyte Count and Mean Cell Hemoglobin in Sickle Cell Anemia

Directory of Open Access Journals (Sweden)

Okocha Chide

2015-12-01

Full Text Available Background Changes in serum micro nutrients levels affect a number of critically important metabolic processes; these could potentially influence blood counts and ultimately disease presentation in patients with sickle cell anemia (SCA. Objectives To evaluate the influence of serum micro-nutrients levels; zinc, copper, selenium and magnesium on blood counts in steady state SCA patients. Methods A cross sectional study that involved 28 steady state adult SCA subjects. Seven milliliters (mls of blood was collected; 3 mls was for hemoglobin electrophoresis and full blood count determination while 4 mls was for measurement of serum micro nutrients levels, by the atomic absorption spectrophotometry. Correlation between serum micro-nutrient levels and blood counts was done by the Pearson’s linear regression. Ethical approval was obtained from the institutional review board and each participant gave informed consent. All data was analyzed by SPSS software version 20. Results There was a significant correlation between serum copper levels and mean cell hemoglobin (MCH, platelet and lymphocyte counts (r = 0.418; P = 0.02, r = -0.376; P = 0.04 and r = -0.383; P = 0.04, respectively. There were no significant correlations between serum levels of other micro nutrients (selenium, zinc and magnesium and blood counts. Conclusions Copper influences blood count in SCA patients probably by inducing red cell haemolysis, oxidant tissue damage and stimulating the immune system.

Mutacins and bacteriocins like genes in Streptococcus mutans isolated from participants with high, moderate, and low salivary count.

Science.gov (United States)

Soto, Carolina; Padilla, Carlos; Lobos, Olga

2017-02-01

To detect S. mutans producers of mutacins and bacteriocins like substances (BLIS) from saliva of participants with low, moderate, and high salivary counts. 123 strains of S. mutans were obtained from participants with low, moderate, and high salivary counts (age 18 and 20 years old) and their antibacterial capacity analyzed. By using PCR amplification, the expression levels of mutacins and BLIS genes were studied (expressed in arbitrary units/ml) in all three levels. S. mutans strains from participants with low salivary counts show high production of mutacins (63%). In contrast, participants with moderate and high salivary counts depict relatively low levels of mutacins (22 and 15%, respectively). Moreover, participants with low salivary counts showed high expression levels of genes encoding mutacins, a result that correlates with the strong antimicrobial activity of the group. Participants with moderate and high salivary counts however depict low expression levels of mutacin related genes, and little antimicrobial activity. No BLIS were detected in any of the groups studied. S. mutans isolated from the saliva of participants with low bacterial counts have significant antibacterial capacity compared to that of participants with moderate and high salivary counts. The superior lethality of S. mutans in participants with low salivary counts is likely due to the augmented expression of mutacin- related genes. Copyright © 2016 Elsevier Ltd. All rights reserved.

A low-level needle counter

International Nuclear Information System (INIS)

Fujita, Y.; Taguchi, Y.; Imamura, M.; Inoue, T.; Tanaka, S.

1977-01-01

A small end-window type gas-flow counter which has a sharpened needle (anode) against the end-window plane (cathode) was developed for low-level counting of β particles to the amount of less than one count per hour in solid sources of relatively high specific activity. The advantage of the needle counter for low-level work is that being of a conical shape the active volume as against the window area is small. The background count rate of 0.0092+-0.0005 cpm was obtained for a 10 mm dia needle counter operating in GM mode and in anticoincidence with a well-type NaI(Tl) guard crystal with massive shields. The counter design and the counter characteristics are presented in detail. The needle counter is simple in design, low-cost and stable in long time operation. (author)

Limit of sensitivity of low-background counting equipment

International Nuclear Information System (INIS)

Homann, S.G.

1991-01-01

The Hazards Control Department's Radiological Measurements Laboratory (RML) analyzes many types of sample media in support of the Laboratory's health and safety program. The Department has determined that the equation for the minimum limit of sensitivity, MDC(α,β) = 2.71 + 3.29 (r b t s ) 1/2 is also adequate for RML counting systems with very-low-background levels. This paper reviews the normal distribution case and address the special case of determining the limit of sensitivity of a counting system when the background count rate is well known and small. In the latter case, we must use an exact test procedure based on the binomial distribution. However, the error in using the normal distribution for calculating a detection system's limit of sensitivity is not significant even as the total observed number of counts approaches or equals zero. 2 refs., 4 figs

The water purification system for the low background counting test facility of the Borexino experiment at Gran Sasso

International Nuclear Information System (INIS)

Balata, M.; Cadonati, L.; Laubenstein, M.; Heusser, G.; Giammarchi, M.G.; Scardaoni, R.; Torri, V.; Cecchet, G.; De Bari, A.; Perotti, A.

1996-01-01

The Borexino experiment, for the study of solar neutrino physics, requires radiopurity at the level of 5 x 10 -16 g/g 238 U equivalent (or 6 x 10 -9 Bq/kg) on a detector mass of many tons of scintillator. Feasibility studies are performed in a counting test facility now operating at LNGS, which consists of 4 t of liquid scintillator viewed by 100 photomultipliers and shielded by 100 t of water. The accomplishment of this goal requires the shielding liquid, water, to be at the 10 -13 g/g contamination level (1.2 x 10 -6 Bq/kg) or better. This paper describes the water purification system; it consists of a combination of several purification processes to remove particulate, radioactive ions, dissolved gases and other impurities. Residual contaminations are measured by analytical or direct-counting techniques. For radon measurement, particularly challenging at this low activity levels, a low background counting method has been developed. (orig.)

Counts of low-Redshift SDSS quasar candidates

International Nuclear Information System (INIS)

Zeljko Ivezic

2004-01-01

We analyze the counts of low-redshift quasar candidates selected using nine-epoch SDSS imaging data. The co-added catalogs are more than 1 mag deeper than single-epoch SDSS data, and allow the selection of low-redshift quasar candidates using UV-excess and also variability techniques. The counts of selected candidates are robustly determined down to g = 21.5. This is about 2 magnitudes deeper than the position of a change in the slope of the counts reported by Boyle (and others) (1990, 2000) for a sample selected by UV-excess, and questioned by Hawkins and Veron (1995), who utilized a variability-selected sample. Using SDSS data, we confirm a change in the slope of the counts for both UV-excess and variability selected samples, providing strong support for the Boyle (and others) results

Results of ultra-low level 71ge counting for application in the Gallex-solar neutrino experiment at the Gran Sasso Underground Physics Laboratory

Science.gov (United States)

Hampel, W.; Heusser, G.; Huebner, M.; Kiko, J.; Kirsten, T.; Schneider, K.; Schlotz, R.

1985-01-01

It has been experimentally verified that the Ultra-Low-Level Counting System for the Gallex solar neutrino experiment is capable of measuring the expected solar up silon-flux to plus or minus 12% during two years of operation.

Beta emitter radionuclides (90Sr contamination in animal feed: validation and application of a radiochemical method by ultra low level liquid scintillation counting

Directory of Open Access Journals (Sweden)

Marco Iammarino

2015-02-01

Full Text Available 90Sr is considered as a dangerous contaminant of agri-food supply chains due to its chemical affinity with Calcium, which makes its absorption in bones easy. 90Sr accumulation in raw materials and then in final products is particularly significant in relationship to its ability to transfer into animal source products. The radionuclides transfer (137Cs and 90Sr from environment to forages and then to products of animal origin (milk, cow and pork meats was studied and evaluated in different studies, which were carried out in contaminated areas, from Chernobyl disaster until today. In the present work, the development and validation of a radiochemical method for the detection of 90Sr in different types of animal feed, and the application of this technique for routinely control activities, are presented. Liquid scintillation counting was the employed analytical technique, since it is able to determine very low activity concentrations of 90Sr (<0.01 Bq kg–1. All samples analysed showed a 90Sr contamination much higher than method detection limit (0.008 Bq kg–1. In particular, the highest mean activity concentration was registered in hay samples (2.93 Bq kg–1, followed by silage samples (2.07 Bq kg–1 and animal feeds (0.77 Bq kg–1. In fact, all samples were characterized by 90Sr activity concentrations much lower than reference limits. This notwithstanding, the necessity to monitor these levels was confirmed, especially considering that 90Sr is a possible carcinogen for human.

Statistical Methods for Unusual Count Data

DEFF Research Database (Denmark)

Guthrie, Katherine A.; Gammill, Hilary S.; Kamper-Jørgensen, Mads

2016-01-01

microchimerism data present challenges for statistical analysis, including a skewed distribution, excess zero values, and occasional large values. Methods for comparing microchimerism levels across groups while controlling for covariates are not well established. We compared statistical models for quantitative...... microchimerism values, applied to simulated data sets and 2 observed data sets, to make recommendations for analytic practice. Modeling the level of quantitative microchimerism as a rate via Poisson or negative binomial model with the rate of detection defined as a count of microchimerism genome equivalents per...

Instrumental analysis by gamma spectrometry of low level caesium-137 in marine samples

International Nuclear Information System (INIS)

Figueira, R.C.L.; Silva, L.R.N.; Figueiredo, A.M.G.; Cunha, I.I.L.

1998-01-01

An instrumental method for the analysis of low levels of 137 Cs in marine samples consists in calibrating the detector, determining the counting efficiency of the detector, accumulative counts of background and sample and smoothing the 661.6 keV photopeak. The methodology was applied to reference samples containing low levels of 137 Cs, showing a good accuracy. It was further applied to sediment samples from the southern coast of Brazil. The levels obtained ranged between 1.0 and 1.8 Bq.kg -1 , and the lower limit of detection and minimum detectable concentration values were 10 mBq and 0.28 Bq.kg -1 , respectively. (author)

Method of processing low-level radioactive liquid wastes

International Nuclear Information System (INIS)

Matsunaga, Ichiro; Sugai, Hiroshi.

1984-01-01

Purpose: To effectively reduce the radioactivity density of low-level radioactive liquid wastes discharged from enriched uranium conversion processing steps or the likes. Method: Hydrazin is added to low-level radioactive liquid wastes, which are in contact with iron hydroxide-cation exchange resins prepared by processing strongly acidic-cation exchange resins with ferric chloride and aqueous ammonia to form hydrorizates of ferric ions in the resin. Hydrazine added herein may be any of hydrazine hydrate, hydrazine hydrochloride and hydranine sulfate. The preferred addition amount is more than 100 mg per one liter of the liquid wastes. If it is less than 100 mg, the reduction rate for the radioactivety density (procession liquid density/original liquid density) is decreased. This method enables to effectively reduce the radioactivity density of the low-level radioactive liquid wastes containing a trace amount of radioactive nucleides. (Yoshihara, H.)

New method of radiation measurement at carbon isotope 14 low level in an environmental atmospheric sampling

International Nuclear Information System (INIS)

Tormos, J.

2009-01-01

A new method of preparation is proposed to extract the atmospheric carbon trapped in the solution of soda coming from air sampling in environment with a carbon-14 bubbler (type H.A.G. 7000). It is based on the neutralisation of the global soda solution got from bubbling pots by nitric acid, the complete desorption of the carbon under gaseous oxidized form (CO 2 ) and its trapping in a only capacity containing a reactive. The whole of the device is scanned by air at steady rate. A test catch of the reactive and of the trapped carbon dioxide is then blended to a glistening liquid (Permafluor E+) and measured in beta counting by scintillation in liquid medium with a counter for the measurement of low energy beta emitters at very low level of activity (Quantulus type). this method allows to get a limit of detection equal to 5 mBq/m 3 for the atmospheric organic carbon. The principal interest of this method is its quickness and simplicity of setting in motion for a measurement of 14 C in the atmospheric carbon dioxide at a level of natural activity. (N.C.)

A simplified method for low-level tritium measurement in the environmental water samples

International Nuclear Information System (INIS)

Sakuma, Yoichi; Yamanishi, Hirokuni; Ogata, Yoshimune

2004-01-01

Low level liquid scintillation counting took much time with a lot of doing to distill off the impurities in the sample water before mixing the sample with the liquid scintillation cocktail. In the light of it, we investigated the possibility of an alternative filtration method for sample purification. The tritium concentration in the environmental water has become very low, and the samples have to be treated by electrolysis enrichment with a liquid scintillation analyzer. Using the solid polymer electrolyte enriching device, there is no need to add neither any electrolyte nor the neutralization after the concentration. If we could replace the distillation process with the filtration, the procedure would be simplified very much. We investigated the procedure and we were able to prove that the reverse osmosis (RO) filtration was available. Moreover, in order to rationalize all through the measurement method, we examined the followings: (1) Improvement of the enriching apparatus. (2) Easier measurement of heavy water concentration using a density meter, instead of a mass spectrometer. The concentration of water samples was measured to determine the enrichment rate of tritium during the electrolysis enrichment. (author)

Low background germanium detectors: From environmental laboratory to underground counting facility

Energy Technology Data Exchange (ETDEWEB)

Ceuppens, M [Canberra Semiconductor N.V., Geel (Belgium); [Canberra Industries, Inc., Meriden (United States); Verplancke, J [Canberra Semiconductor N.V., Geel (Belgium); [Canberra Industries, Inc., Meriden (United States); Tench, O [Canberra Semiconductor N.V., Geel (Belgium); [Canberra Industries, Inc., Meriden (United States)

1997-03-01

Presentation and overview of different Low Level measuring systems ranging from the environmental lab to low-background detection systems and to the deep underground counting facility. Examples and performances for each of these will be given. Attention will be given to the standardised ultra low-background detectors and shields which provide excellent performance without the high cost in time and money associated with custom designed systems. (orig./DG)

Low background germanium detectors: From environmental laboratory to underground counting facility

International Nuclear Information System (INIS)

Ceuppens, M.; Verplancke, J.; Tench, O.

1997-01-01

Presentation and overview of different Low Level measuring systems ranging from the environmental lab to low-background detection systems and to the deep underground counting facility. Examples and performances for each of these will be given. Attention will be given to the standardised ultra low-background detectors and shields which provide excellent performance without the high cost in time and money associated with custom designed systems. (orig./DG)

Low-level counting techniques in the underground laboratory `Felsenkeller` in Dresden

Energy Technology Data Exchange (ETDEWEB)

Niese, S [Nuclear Engineering and Analytics Rossendorf, Inc., Dresden (Germany); Koehler, M [Nuclear Engineering and Analytics Rossendorf, Inc., Dresden (Germany)

1997-03-01

Low radioactivity measurements are characterized by low detection limits. They are mainly determined by the background. The contribution of cosmic rays may be reduced drastically by installation of measurement devices in an underground laboratory. In 1982 we installed a chamber with a shield of ultramafic rock for low-level measurements within a cave of an old brewery named `Felsenkeller`. In this laboratory we used low-level {gamma}-spectrometry for the measurement of neutron activated samples of semiconductor silicon (Niese (1986)), of cosmic induced radioactivity in meteorites, chemically separated long-lived nuclides in low-level wastes, contaminated materials and of environmental samples. (orig./DG)

Intercomparison of low-level tritium in water

International Nuclear Information System (INIS)

Sipka, V.; Zupancic, M.; Hadzisehovic, M.; Bacic, S.; Vukovic, Z.

1989-01-01

In 1985 the Section of Isotope Hydrology of the IAEA organized the fourth intercomparison for low-level tritium counting in waters. Four water samples with different 3 H concentration were sent to 85 laboratories willing to participate. The results from the different laboratories were presented in the unified questionnaires and coded. The participation in the intercomparisons for every laboratory doing low-level 3 H measurements in the waters is very important and useful. This is a best way to check the entire procedure and methods of the measurements and the reliability of the standards used. Since our laboratories are doing the natural 3 H concentration measurement in the waters for the environmental control and hydrology reasons it was necessary to take part in this intercomparison. Our standard procedure was applied. The 3 H activity in the samples was measured by liquid scintillation counting after an electrolytic enrichment. The results of our measurements of the four water samples, received from the organizers, are presented on the figures and tables presenting summary of the intercomparison. It is clear that our measurement (procedure and standards) have given satisfactory results (author)

Determination of 129I in low level radioactive waste by two different methods

International Nuclear Information System (INIS)

Szanto, Zs.; Szucs, Z.; Svingor, E.; Molnar, M.; Palcsu, L.; Futo, I.; Vajda, N.; Molnar, Zs.; Kabai, E.

2001-01-01

Determination of the physical, chemical and radiological properties of wastes intended for disposal in any radwaste repository represents one of the major goals of every country dealing with nuclear facilities. In most disposal facilities the long lived α- and β-emitting radionuclides have the most restrictive inventory limits, because they do not decay appreciably in the lifetime of the facility. One of the most restrictive radionuclides is 129 I, a fission product with long half- life, high mobility and biological hazard for the human body. The purpose of this paper is to present and to compare the 129 I results obtained by two different Institutes, using different measurement methods on a wide variety of low level radioactive waste streams generated at the Paks NPP. The Institute of Nuclear Technique of the Technical and Economical University of Budapest analyzed 129 I in a sequential scheme that included preconcentration, neutron activation, post-irradiation chemistry and counting of the shorter-lived 130 I activation product, while the Institute of Nuclear Research of the Hungarian Academy of Sciences used radiochemical separation followed by low-energy direct gamma-ray spectrometry. The results show a good correlation and prove the availability of both measurement methods.(author)

Characterization of actinide targets by low solid-angle alpha particle counting

CERN Document Server

Denecke, B; Pauwels, J; Robouch, P; Gilliam, D M; Hodge, P; Hutchinson, J M R; Nico, J S

1999-01-01

Actinide samples were characterized in an interlaboratory comparison between IRMM and NIST, including alpha-particle counting at defined low solid angle and counting in a 2 pi proportional gas counter. For this comparison, nine sup 2 sup 3 sup 3 UF sub 4 samples with high uniformity in the layer thickness were prepared at IRMM by deposition under vacuum. Polished silicon wafers were used as source substrates, and these were rotated during the deposition using a planetary rotation system. The estimated uncertainties for the defined low solid-angle methods were about 0.1% at both NIST and IRMM. The agreement of reported alpha-particle emission rates in the energy range 2.5-5.09 MeV was better than or equal to 0.02% for the defined solid-angle methods. When comparing total alpha-particle emission rates over the larger energy range 0-9 MeV (which includes all emissions from the daughter nuclides and the impurities), the agreement of the defined solid-angle methods was better than or equal to 0.05%. The 2 pi propo...

Metal ion levels and lymphocyte counts

DEFF Research Database (Denmark)

Penny, Jeannette Ø; Varmarken, Jens-Erik; Ovesen, Ole

2013-01-01

BACKGROUND AND PURPOSE: Wear particles from metal-on-metal arthroplasties are under suspicion for adverse effects both locally and systemically, and the DePuy ASR Hip Resurfacing System (RHA) has above-average failure rates. We compared lymphocyte counts in RHA and total hip arthroplasty (THA) an....../ppb. INTERPRETATION: Circulating T-lymphocyte levels may decline after surgery, regardless of implant type. Metal ions-particularly cobalt-may have a general depressive effect on T- and B-lymphocyte levels. Registered with ClinicalTrials.gov under # NCT01113762.......BACKGROUND AND PURPOSE: Wear particles from metal-on-metal arthroplasties are under suspicion for adverse effects both locally and systemically, and the DePuy ASR Hip Resurfacing System (RHA) has above-average failure rates. We compared lymphocyte counts in RHA and total hip arthroplasty (THA....... RESULTS: The T-lymphocyte counts for both implant types declined over the 2-year period. This decline was statistically significant for CD3(+)CD8(+) in the THA group, with a regression coefficient of -0.04 × 10(9)cells/year (95% CI: -0.08 to -0.01). Regression analysis indicated a depressive effect...

How much locomotive activity is needed for an active physical activity level: analysis of total step counts

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Ohkawara Kazunori

2011-11-01

Full Text Available Abstract Background Although physical activity recommendations for public health have focused on locomotive activity such as walking and running, it is uncertain how much these activities contribute to overall physical activity level (PAL. The purpose of the present study was to determine the contribution of locomotive activity to PAL using total step counts measured in a calorimeter study. Methods PAL, calculated as total energy expenditure divided by basal metabolic rate, was evaluated in 11 adult men using three different conditions for 24-hour human calorimeter measurements: a low-activity day (L-day targeted at a low active level of PAL (1.45, and a high-frequency moderate activity day (M-day or a high-frequency vigorous activity day (V-day targeted at an active level of PAL (1.75. These subjects were permitted only light activities except prescribed activities. In a separate group of 41 adults, free-living PAL was evaluated using doubly-labeled water (DLW. In both experiments, step counts per day were also measured using an accelerometer. Results In the human calorimeter study, PAL and step counts were 1.42 ± 0.10 and 8,973 ± 543 steps/d (L-day, 1.82 ± 0.14 and 29,588 ± 1,126 steps/d (M-day, and 1.74 ± 0.15 and 23,755 ± 1,038 steps/d (V-day, respectively. In the DLW study, PAL and step counts were 1.73 ± 0.15 and 10,022 ± 2,605 steps/d, and there was no significant relationship between PAL and daily step counts. Conclusions These results indicate that an enormous number of steps are needed for an active level of PAL if individuals extend physical activity-induced energy expenditure by only locomotive activity. Therefore, non-locomotive activity such as household activity should also play a significant role in increasing PAL under free-living conditions.

Tower counts

Science.gov (United States)

Woody, Carol Ann; Johnson, D.H.; Shrier, Brianna M.; O'Neal, Jennifer S.; Knutzen, John A.; Augerot, Xanthippe; O'Neal, Thomas A.; Pearsons, Todd N.

2007-01-01

Counting towers provide an accurate, low-cost, low-maintenance, low-technology, and easily mobilized escapement estimation program compared to other methods (e.g., weirs, hydroacoustics, mark-recapture, and aerial surveys) (Thompson 1962; Siebel 1967; Cousens et al. 1982; Symons and Waldichuk 1984; Anderson 2000; Alaska Department of Fish and Game 2003). Counting tower data has been found to be consistent with that of digital video counts (Edwards 2005). Counting towers do not interfere with natural fish migration patterns, nor are fish handled or stressed; however, their use is generally limited to clear rivers that meet specific site selection criteria. The data provided by counting tower sampling allow fishery managers to determine reproductive population size, estimate total return (escapement + catch) and its uncertainty, evaluate population productivity and trends, set harvest rates, determine spawning escapement goals, and forecast future returns (Alaska Department of Fish and Game 1974-2000 and 1975-2004). The number of spawning fish is determined by subtracting subsistence, sport-caught fish, and prespawn mortality from the total estimated escapement. The methods outlined in this protocol for tower counts can be used to provide reasonable estimates ( plus or minus 6%-10%) of reproductive salmon population size and run timing in clear rivers. 

Application of nuclear activation analysis (NAA) and low-level gamma counting to determine the radionuclide and trace element pollutant releases from coal-fired power plants in Vietnam

International Nuclear Information System (INIS)

Vanduong, P.; Thanh, V.T.; Dien, P.Q.; Binh, N.T.

1995-01-01

Results are reported of the application of NAA using research reactors TRIGA II in Dalat, Vietnam, and Vienna, Austria (with pyrolysis separation for Hg, Se, and As before irradiation), to determine As, Cd, Cu, Hg, Ni, Co, Pb, Sn and Zn. Low-level gamma counting was used to measure Ra-226, Th-228 and K-40, released from coal-fired power plants in Vietnam. Results showed that: (1) the content of the air pollutants in the vicinity of the operating power plants (in 1991, the Phalai plant produced 1700 million kWh, and the Ninhbinh plant 100 million kWh) depends on the coal combustion which is used for their applied operation technology, both plants used Quangninh anthracite as fuel. The content of trace elements pollutants (TEP) in the environment of the Ninhbinh plant is higher than in the Phalai plant. (2) In the vicinity of both plants, rain water is highly polluted by trace elements such as As, Cu, Pb, Hg, Ni, Co, Cd, Se, U, Th and sulphuric acid. Therefore, this kind of water is not acceptable for human consumption. (3) The algae growing in the waterfield in the vicinity of the power plants can be used to monitor TEP. Four NAA methods, in combination with low-level gamma counting and AAS, can be successfully used to monitor TEP released from power plants

Low level scintillation counting of 239Pu

International Nuclear Information System (INIS)

Fueloep, M.; Minarik, F.; Cierna, V.

1984-01-01

For measuring the content of 239 Pu in samples taken from the working or living environment, methods should be used which are sufficiently sensitive for determining activities of the order of 10 -3 Bq. It is useful to use liquid scintillators for reasons of their 4π geometry and the exclusion of kinetic energy losses of particles detected in the sample and on the path between the sample and the detector. The method of background discrimination according to pulse shape may be used to suppress gamma background in the area of alpha particle peaks to the level 2.5x10 -4 s -1 . The diagram is given of electronic circuits for shape discrimination. The scintillator used was a SLS-31 with a PBD activator, a POPOP spectrum shifter and a mixture of solvents: toluene, dioxane and methanol. The efficiency of 239 Pu alpha particle detection is estimated at 78% and may further be improved by improving shape discrimination. (M.D.)

Antiretroviral treatment cohort analysis using time-updated CD4 counts: assessment of bias with different analytic methods.

Directory of Open Access Journals (Sweden)

Katharina Kranzer

Full Text Available Survival analysis using time-updated CD4+ counts during antiretroviral therapy is frequently employed to determine risk of clinical events. The time-point when the CD4+ count is assumed to change potentially biases effect estimates but methods used to estimate this are infrequently reported.This study examined the effect of three different estimation methods: assuming i a constant CD4+ count from date of measurement until the date of next measurement, ii a constant CD4+ count from the midpoint of the preceding interval until the midpoint of the subsequent interval and iii a linear interpolation between consecutive CD4+ measurements to provide additional midpoint measurements. Person-time, tuberculosis rates and hazard ratios by CD4+ stratum were compared using all available CD4+ counts (measurement frequency 1-3 months and 6 monthly measurements from a clinical cohort. Simulated data were used to compare the extent of bias introduced by these methods.The midpoint method gave the closest fit to person-time spent with low CD4+ counts and for hazard ratios for outcomes both in the clinical dataset and the simulated data.The midpoint method presents a simple option to reduce bias in time-updated CD4+ analysis, particularly at low CD4 cell counts and rapidly increasing counts after ART initiation.

The measurement of Rn-222 in drinking water by low-level liquid scintillation counting

International Nuclear Information System (INIS)

Barnett, J.M.; McKlveen, J.W.

1991-01-01

Radon-222 has consistently been found in well water. The research objectives are to establish a method to collect well water and to measure the Rn in ground water using liquid scintillation (LS) counting. Water is collected at the well head while the well is pumping. The water is adjusted to a slow, non-aerated, steady flow through a clear tube, and a 437 mL (16 oz) glass bottle is filled. The sample is tightly capped after a high meniscus has developed. In the laboratory, standard 22 mL LS glass vials are filled with 10 mL of a toluene based mineral oil LS cocktail. Then, two 5 mL sample aliquots are pipetted into the vial. Vials are capped tightly, shaken vigorously, and placed in the LS counter. Secular equilibrium is established in approximately 3.5 hours, after which samples are counted for 100 minutes each. Quality assurance and control is performed weekly on the LS counter's electronics, spectral window, counting efficiency, and background. The counting efficiency ranges between 315-345 percent depending on the chosen spectral window. The average background is about 6 cpm. A total of 28 wells were tested for Rn in the Carefree-Cave Creek, Arizona, USA area, and 12 wells were selected, each over 50 Bq/L (1,350 pCi/L), for an extended 6 month period. The area's average Rn concentration was found to be 46.5 Bq/L (1,255 pCi/L); it is a geometric mean. The associated estimated lung dose is 1.13 mSv/a

Considerations for achieving low level radioactivity measurements with liquid scintillation counters

International Nuclear Information System (INIS)

Noakes, J.E.

1977-01-01

Low level LS counting requires that the most rigorous standards be maintained in sample preparation, instrument stability and low background operation. In order to achieve these goals, one must pay particular attention to sample chemistry and cocktail selection in order to minimize quench and obtain the highest counting efficiency. The use of special low volume vials, fabricated for positive seal and with material of low cocktail permeability and low natural radioactivity, is one of the most economical means for lowering background and reducing sample loss during long counting periods. Acquisition of select high quantum yield low noise PMT's is an excellent way to achieve high counting efficiency and lower electronic-generated background. Radiation shielding both by massive and electronic guards is the most important means for reducing background caused by external radiation sources. Pulse height discrimination and fast pulse time circuitry can both be applied with fast coincidence counting for background reduction. PSA can be applied to β, γ and β-γ counting and as a means for background reduction. 8 figures, 3 tables

Low white blood cell count and cancer

Science.gov (United States)

... gov/ency/patientinstructions/000675.htm Low white blood cell count and cancer To use the sharing features on this page, please enable JavaScript. White blood cells (WBCs) fight infections from bacteria, viruses, fungi, and ...

Accuracy of Platelet Counting by Optical and Impedance Methods in Patients with Thrombocytopaenia and Microcytosis

Directory of Open Access Journals (Sweden)

Mohamed-Rachid Boulassel

2015-11-01

Full Text Available Objectives: Obtaining accurate platelet counts in microcytic blood samples is challenging, even with the most reliable automated haematology analysers. The CELL-DYN™ Sapphire (Abbott Laboratories, Chicago, Illinois, USA analyser uses both optical density and electronic impedance methods for platelet counting. This study aimed to evaluate the accuracy of optical density and electrical impedance methods in determining true platelet counts in thrombocytopaenic samples with microcytosis as defined by low mean corpuscular volume (MCV of red blood cells. Additionally, the impact of microcytosis on platelet count accuracy was evaluated. Methods: This study was carried out between February and December 2014 at the Haematology Laboratory of the Sultan Qaboos University Hospital in Muscat, Oman. Blood samples were collected and analysed from 189 patients with thrombocytopaenia and MCV values of <76 femtolitres. Platelet counts were tested using both optical and impedance methods. Stained peripheral blood films for each sample were then reviewed as a reference method to confirm platelet counts. Results: The platelet counts estimated by the impedance method were on average 30% higher than those estimated by the optical method (P <0.001. The estimated intraclass correlation coefficient was 0.52 (95% confidence interval: 0.41–0.62, indicating moderate reliability between the methods. The degree of agreement between methods ranged from -85.5 to 24.3 with an estimated bias of -30, suggesting that these methods generate different platelet results. Conclusion: The impedance method significantly overestimated platelet counts in microcytic and thrombocytopaenic blood samples. Further attention is therefore needed to improve the accuracy of platelet counts, particularly for patients with conditions associated with microcytosis.

Sample to answer visualization pipeline for low-cost point-of-care blood cell counting

Science.gov (United States)

Smith, Suzanne; Naidoo, Thegaran; Davies, Emlyn; Fourie, Louis; Nxumalo, Zandile; Swart, Hein; Marais, Philip; Land, Kevin; Roux, Pieter

2015-03-01

We present a visualization pipeline from sample to answer for point-of-care blood cell counting applications. Effective and low-cost point-of-care medical diagnostic tests provide developing countries and rural communities with accessible healthcare solutions [1], and can be particularly beneficial for blood cell count tests, which are often the starting point in the process of diagnosing a patient [2]. The initial focus of this work is on total white and red blood cell counts, using a microfluidic cartridge [3] for sample processing. Analysis of the processed samples has been implemented by means of two main optical visualization systems developed in-house: 1) a fluidic operation analysis system using high speed video data to determine volumes, mixing efficiency and flow rates, and 2) a microscopy analysis system to investigate homogeneity and concentration of blood cells. Fluidic parameters were derived from the optical flow [4] as well as color-based segmentation of the different fluids using a hue-saturation-value (HSV) color space. Cell count estimates were obtained using automated microscopy analysis and were compared to a widely accepted manual method for cell counting using a hemocytometer [5]. The results using the first iteration microfluidic device [3] showed that the most simple - and thus low-cost - approach for microfluidic component implementation was not adequate as compared to techniques based on manual cell counting principles. An improved microfluidic design has been developed to incorporate enhanced mixing and metering components, which together with this work provides the foundation on which to successfully implement automated, rapid and low-cost blood cell counting tests.

A Method Validation for Determination of Gross Alpha and Gross Beta in Water Sample Using Low Background Gross Alpha/ Beta Counting System

International Nuclear Information System (INIS)

Zal Uyun Wan Mahmood; Norfaizal Mohamed; Nita Salina Abu Bakar

2016-01-01

Method validation (MV) for the measurement of gross alpha and gross beta activity in water (drinking, mineral and environmental) samples using Low Background Gross Alpha/ Beta Counting System was performed to characterize precision, accuracy and reliable results. The main objective of this assignment is to ensure that both the instrument and method always good performed and resulting accuracy and reliable results. Generally, almost the results of estimated RSD, z-score and U_s_c_o_r_e were reliable which are recorded as ≤30 %, less than 2 and less than 1.5, respectively. Minimum Detected Activity (MDA) was estimated based on the counting time of 100 minutes and present background counting value of gross alpha (0.01 - 0.35 cpm) and gross beta (0.50 - 2.18 cpm). Estimated Detection Limit (DL) was 0.1 Bq/ L for gross alpha and 0.2 Bq/ L for gross beta and expended uncertainty was relatively small of 9.77 % for gross alpha and 10.57 % for gross beta. Align with that, background counting for gross alpha and gross beta was ranged of 0.01 - 0.35 cpm and 0.50 - 2.18 cpm, respectively. While, sample volume was set at minimum of 500 mL and maximum of 2000 mL. These proven the accuracy and precision result that are generated from developed method/ technique is satisfactory and method is recommended to be used. Therefore, it can be concluded that the MV found no doubtful on the ability of the developed method. The test result showed the method is suitable for all types of water samples which are contained several radionuclides and elements as well as any impurities that interfere the measurement analysis of gross alpha and gross beta. (author)

Complementary frame reconstruction: a low-biased dynamic PET technique for low count density data in projection space

International Nuclear Information System (INIS)

Hong, Inki; Cho, Sanghee; Michel, Christian J; Casey, Michael E; Schaefferkoetter, Joshua D

2014-01-01

A new data handling method is presented for improving the image noise distribution and reducing bias when reconstructing very short frames from low count dynamic PET acquisition. The new method termed ‘Complementary Frame Reconstruction’ (CFR) involves the indirect formation of a count-limited emission image in a short frame through subtraction of two frames with longer acquisition time, where the short time frame data is excluded from the second long frame data before the reconstruction. This approach can be regarded as an alternative to the AML algorithm recently proposed by Nuyts et al, as a method to reduce the bias for the maximum likelihood expectation maximization (MLEM) reconstruction of count limited data. CFR uses long scan emission data to stabilize the reconstruction and avoids modification of algorithms such as MLEM. The subtraction between two long frame images, naturally allows negative voxel values and significantly reduces bias introduced in the final image. Simulations based on phantom and clinical data were used to evaluate the accuracy of the reconstructed images to represent the true activity distribution. Applicability to determine the arterial input function in human and small animal studies is also explored. In situations with limited count rate, e.g. pediatric applications, gated abdominal, cardiac studies, etc., or when using limited doses of short-lived isotopes such as 15 O-water, the proposed method will likely be preferred over independent frame reconstruction to address bias and noise issues. (paper)

Simultaneous and separate, low background counting of beta rays and gamma rays using the phoswich principle

International Nuclear Information System (INIS)

Mayhugh, M.R.; Utts, B.K.; Shoffner, B.M.

1978-01-01

A phoswich constructed using thin calcium fluoride optically coupled to a thicker sodium iodide crystal and operated with pulse shape analysis equipment can be used as an efficient low background counting assembly. Low background in the beta ray counting channel is achieved by judicious choice of pure materials in the assembly and by operating the analysis equipment so as to reject background events which occur simultaneously in the sodium iodide crystal. Careful survey of construction materials and methods has resulted in reducing beta ray counting background to 0.6 c/min for a 2-inch diameter assembly. The radioactivity of typical building materials will be discussed. A pulse shape analyzer has been constructed which provides separately adjusted time windows and separate output information for the beta ray and gamma ray channels. The dual channel capability combined with the low beta ray background reduces the sample counting time significantly for typical laboratory samples. (author)

Counting skills intervention for low-performing first graders

Directory of Open Access Journals (Sweden)

Riikka Mononen

2016-09-01

Conclusion: A relatively short counting skills intervention that applied explicit teaching showed promising effects in improving low-performing children’s mathematical performance as a supplemental instruction.

Low-Noise Free-Running High-Rate Photon-Counting for Space Communication and Ranging

Science.gov (United States)

Lu, Wei; Krainak, Michael A.; Yang, Guan; Sun, Xiaoli; Merritt, Scott

2016-01-01

We present performance data for low-noise free-running high-rate photon counting method for space optical communication and ranging. NASA GSFC is testing the performance of two types of novel photon-counting detectors 1) a 2x8 mercury cadmium telluride (HgCdTe) avalanche array made by DRS Inc., and a 2) a commercial 2880-element silicon avalanche photodiode (APD) array. We successfully measured real-time communication performance using both the 2 detected-photon threshold and logic AND-gate coincidence methods. Use of these methods allows mitigation of dark count, after-pulsing and background noise effects without using other method of Time Gating The HgCdTe APD array routinely demonstrated very high photon detection efficiencies (50) at near infrared wavelength. The commercial silicon APD array exhibited a fast output with rise times of 300 ps and pulse widths of 600 ps. On-chip individually filtered signals from the entire array were multiplexed onto a single fast output. NASA GSFC has tested both detectors for their potential application for space communications and ranging. We developed and compare their performances using both the 2 detected photon threshold and coincidence methods.

A gravimetric simplified method for nucleated marrow cell counting using an injection needle.

Science.gov (United States)

Saitoh, Toshiki; Fang, Liu; Matsumoto, Kiyoshi

2005-08-01

A simplified gravimetric marrow cell counting method for rats is proposed for a regular screening method. After fresh bone marrow was aspirated by an injection needle, the marrow cells were suspended in carbonate buffered saline. The nucleated marrow cell count (NMC) was measured by an automated multi-blood cell analyzer. When this gravimetric method was applied to rats, the NMC of the left and right femurs had essentially identical values due to careful handling. The NMC at 4 to 10 weeks of age in male and female Crj:CD(SD)IGS rats was 2.72 to 1.96 and 2.75 to 1.98 (x10(6) counts/mg), respectively. More useful information for evaluation could be obtained by using this gravimetric method in addition to myelogram examination. However, some difficulties with this method include low NMC due to blood contamination and variation of NMC due to handling. Therefore, the utility of this gravimetric method for screening will be clarified by the accumulation of the data on myelotoxicity studies with this method.

System and method of liquid scintillation counting

International Nuclear Information System (INIS)

Rapkin, E.

1977-01-01

A method of liquid scintillation counting utilizing a combustion step to overcome quenching effects comprises novel features of automatic sequential introduction of samples into a combustion zone and automatic sequential collection and delivery of combustion products into a counting zone. 37 claims, 13 figures

Fast sequential Monte Carlo methods for counting and optimization

CERN Document Server

Rubinstein, Reuven Y; Vaisman, Radislav

2013-01-01

A comprehensive account of the theory and application of Monte Carlo methods Based on years of research in efficient Monte Carlo methods for estimation of rare-event probabilities, counting problems, and combinatorial optimization, Fast Sequential Monte Carlo Methods for Counting and Optimization is a complete illustration of fast sequential Monte Carlo techniques. The book provides an accessible overview of current work in the field of Monte Carlo methods, specifically sequential Monte Carlo techniques, for solving abstract counting and optimization problems. Written by authorities in the

Low level photoneutron detection equipment

International Nuclear Information System (INIS)

Ji Changsong; Zhang Yuqin; Li Yuansui

1991-01-01

A low level photoneutron detection equipment has been developed. The photoneutrons produced by interaction of 226 Ra gamma quanta and deutron (D) target are detected with n-n discrimination detector made up of 3 He proportional counter array. The D-content information in the target can be obtained from the measured photoneutron counts. The equipment developed is mainly used for nondestructive D-content measurement of D-devices

Sex based levels of C-reactive protein and white blood cell count in subjects with metabolic syndrome: Isfahan Healthy Heart Program.

Science.gov (United States)

Gharipour, Mojgan; Ramezani, Mohammad Arash; Sadeghi, Masuomeh; Khosravi, Alireza; Masjedi, Mohsen; Khosravi-Boroujeni, Hossein; Rafieian-Kopaei, Mahmoud; Sarrafzadegan, Nizal

2013-06-01

C-reactive protein (CRP) and white blood cell (WBC) are proinflammatory markers. They are major pathophysiological for the development of metabolic syndrome (MetS). This study aimed to address the independent associations between MetS and WBC counts and serum CRP levels and evaluation of their magnitude in relation to the MetS, based on the sex in the Iranian adults. In this cross-sectional study, subjects who met the MetS criteria, based on the Adult Treatment Panel III were selected from the Isfahan Healthy Heart Program database. A questionnaire containing the demographic data, weight, height, waist, and hip circumference of the respondents was completed for each person. Blood pressure was measured and the anthropometric measurements were done, and fasting blood samples were taken for 2 h postload plasma glucose (2 hpp). Serum [total, high-density lipoprotein (HDL), and low-density lipoprotein] levels of cholesterol, triglyceride, and CRP as well as WBC counts were determined. The univariate analyses were carried out to assess the relation between the CRP levels, WBC counts with the MetS in both sexes the. In men with the abdominal obesity, the higher levels of WBC count, high serum triglyceride and blood glucose levels, a low serum HDL level, and raised systolic and diastolic blood pressure were observed. However, the higher serum CRP levels were only observed in those with the low serum HDL-cholesterol levels. The mean values of the WBC counts were statistically different between the men with and without MetS, but the mean values of the CRP levels were similar between the two groups. In women, the mean values of WBC count and CRP levels were statistically different in the subjects with and without a MetS components (except for the low serum HDL levels and high diastolic blood pressure for the WBC measures and abdominal obesity for the CRP measures) and for those with and without MetS. The age and smoking adjusted changes in the CRP levels and WBC counts

Bayesian analysis of energy and count rate data for detection of low count rate radioactive sources.

Science.gov (United States)

Klumpp, John; Brandl, Alexander

2015-03-01

A particle counting and detection system is proposed that searches for elevated count rates in multiple energy regions simultaneously. The system analyzes time-interval data (e.g., time between counts), as this was shown to be a more sensitive technique for detecting low count rate sources compared to analyzing counts per unit interval (Luo et al. 2013). Two distinct versions of the detection system are developed. The first is intended for situations in which the sample is fixed and can be measured for an unlimited amount of time. The second version is intended to detect sources that are physically moving relative to the detector, such as a truck moving past a fixed roadside detector or a waste storage facility under an airplane. In both cases, the detection system is expected to be active indefinitely; i.e., it is an online detection system. Both versions of the multi-energy detection systems are compared to their respective gross count rate detection systems in terms of Type I and Type II error rates and sensitivity.

Method of inspecting Raschig rings by neutron absorption counting

International Nuclear Information System (INIS)

Morris, R.N.; Murri, R.L.; Hume, M.W.

1979-01-01

A neutron counting method for inspecting borosilicate glass Raschig rings and an apparatus designed specifically for this method are discussed. The neutron count ratios for rings of a given thickness show a linear correlation to the boron oxide content of the rings. The count ratio also has a linear relationship to the thickness of rings of a given boron oxide content. Consequently, the experimentally-determined count ratio and physically-measured thickness of Raschig rings can be used to statistically predict their boron oxide content and determine whether or not they meet quality control acceptance criteria

Determination of plutonium-241 by liquid scintillation counting method and its application to environmental samples

International Nuclear Information System (INIS)

Watanabe, Miki; Amano, Hikaru

1997-03-01

Radionuclides are usually measured by gross counting mode in liquid scintillator counting (LSC) which measures both α and β pulses. This method can easily measure radioactivities, but its background counting is high. Recently reported α-β pulse shape discrimination method (α-β PSD method) in LSC which distinguishes α pulses from β pulses, shows low background counting, so it makes the detection limit lower. The aim of this research is to develop the best method for the determination of 241 Pu which is β-emitter, and Pu isotopes of α-emitters which have long half-lives and stay long in animal body. In this research, two LSC machines was carried out in different scintillators, vial volumes, measurement modes and so on. The following things were found. 1. The liquid scintillator based on naphthalene is proved to be the best separator of α-ray from β-ray, because it acts quickly in energy translation procedure between solvent and aromatic compounds. 2. α-β PSD method makes the background counting rate ten times lower than usual method. It makes the measurement performance better. 3. It is possible to determine 241 Pu in environmental samples around Chernobyl by the combination of LSC and radiochemical separation methods. (author)

PROMETHEE: An Alpha Low Level Waste Assay System Using Passive and Active Neutron Measurement Methods

International Nuclear Information System (INIS)

Passard, Christian; Mariani, Alain; Jallu, Fanny; Romeyer-Dherbey, Jacques; Recroix, Herve; Rodriguez, Michel; Loridon, Joel; Denis, Caroline; Toubon, Herve

2002-01-01

The development of a passive-active neutron assay system for alpha low level waste characterization at the French Atomic Energy Commission is discussed. Less than 50 Bq[α] (about 50 μg Pu) per gram of crude waste must be measured in 118-l 'European' drums in order to reach the requirements for incinerating wastes. Detection limits of about 0.12 mg of effective 239 Pu in total active neutron counting, and 0.08 mg of effective 239 Pu coincident active neutron counting, may currently be detected (empty cavity, measurement time of 15 min, neutron generator emission of 1.6 x 10 8 s -1 [4π]). The most limiting parameters in terms of performances are the matrix of the drum - its composition (H, Cl...), its density, and its heterogeneity degree - and the localization and self-shielding properties of the contaminant

Application of RI-counting method for posttraumatic CSF rhinorrhea

International Nuclear Information System (INIS)

Itoh, Takahiko; Terai, Yoshinori; Fujimoto, Shunichiro; Kawauchi, Masamitsu.

1987-01-01

Numerous techniques and procedures have been reported for the evaluation of CSF fistulas. Especially metrizamide CT cisternography and radioisotope (RI) cisternography have been reported to be reliable for localizing the site of CSF leakage, however, it has been difficult to diagnose the existence and the site of CSF leakages in some cases. RI-counting method, measuring RI-count of intranasal cotton pledgets after the intrathecal injection of RI ( 111 In-DTPA) is thought to be the most reliable method for detecting the presence of CSF leakage in these cases. We used six cotton pledgets which were inserted into upper, middle, and lower meatuses on both side. Because the site of pledgets with ghest RI-count has anatomical relationship to the opening of the paranasal sinus, we can surmise the leakage of dural defect and CSF leakage. RI counting method was applied to two patients in whom it was difficult to diagnose the presence of CSF leakage with other procedures. The patients were free in position for four hours after the intrathecal injection of RI, and in the prone position for 30 minutes before RI-counting of intranasal cotton pledgets. After measuring the RI-counts of six pledgets, the counts were compared with each other. The cotton pledget inserted into left middle meatus showed the highest count in both cases. From this result and finding of conventional skull tomography we speculated the site of CSF leakage to be frontal sinus or ethmoid sinus. Operation demonstrated the opening of dura into the frontal sinus in one case, and ethmoid sinus in another case. As mentioned above, RI-counting method has the advantages of detecting the existence and the site of CSF leakage. (author)

Discussion on the methods for calculation release limits for low-level radioactive waste

International Nuclear Information System (INIS)

Cao Fengbo; Liu Xiaochao

2012-01-01

The release request for low-level radioactive waste are briefly described in this paper. Associating with the conditions of low-level radioactive waste of some radioactive waste processing station, the methods and gist for calculating release limits for low-level radioactive waste with national release limits and annual effective dose limit for the public or the occupation are discussed. Then release limits for the low-level radioactive waste are also proposed. (authors)

Method validation and verification in liquid scintillation counting using the long-term uncertainty method (LTUM) on two decades of proficiency test data

International Nuclear Information System (INIS)

Verrezen, F.; Vasile, M.; Loots, H.; Bruggeman, M.

2017-01-01

Results from proficiency tests gathered over the past two decades by the laboratory for low level radioactivity measurements for liquid scintillation counting of 3 H (184 results) and 14 C (74 results) are used to verify the validated measurement methods used by the laboratory, in particular the estimated uncertainty budget of the method and its reproducibility and stability. A linear regression approach is used for the analysis of the results, described in the literature as the long term uncertainty in measurement method. The present study clearly indicates the advantages of using proficiency test results in identifying possible constant or proportional bias effects as well as the possibility to compare the laboratory performance with the performance of peer laboratories. (author)

White blood cell counts, insulin resistance, vitamin D levels and sarcopenia in Korean elderly men.

Science.gov (United States)

Kim, Sang-Hwan; Kwon, Hyun Seok; Hwang, Hee-Jin

2017-05-01

Sarcopenia is a major determinant of frailty, disability and mortality in the elderly. Whether low-grade inflammation, insulin resistance and vitamin D are independently associated with sarcopenia remains unclear. In our study, sarcopenia was defined as an appendicular skeletal muscle mass divided by height squared (ASM/Ht 2 ) that was sarcopenia in Korean elderly men aged more than 65 years was 11.2%. ASM/Ht 2 were positively associated with vitamin D levels, but negatively associated with white blood cell counts and HOMA-IR by multiple regression analysis. After adjustment for covariables, sarcopenia was associated with the highest quartile of WBC counts (OR = 2.93, 95% CI = 1.21-7.14) and the highest quartile of serum vitamin D levels (OR = 0.38, 95% CI = 0.15-0.95). In conclusion, the study findings suggest that higher WBC counts and lower vitamin D levels are independently associated with the presence of sarcopenia in community-dwelling elderly men. They also provide a basis for further studies of the complex immune-endocrine network in sarcopenia.

Low gamma counting for measuring NORM/TENORM with a radon reducing system

International Nuclear Information System (INIS)

Paschoa, A.S.

2000-01-01

A detection system for counting low levels of gamma radiation was developed by upgrading an existing whole body counter. The main shielding is a rectangular chamber made of 18 metric tons of steel fabricated before the World War II. The ceiling and floor are 0.20 m in thickness, and the walls 0.10 m. The internal walls, the ceiling and the floor of the chamber are covered with copper sheets 1.0 mm in thickness. The new detection system consists of a stainless steel hollow cylinder with variable circular apertures in the cylindrical wall and in the base, to allow NaI(Tl) and/or HPGe detectors in its interior. This counting system is mounted inside the larger shielding chamber, which in turn is located in a subsurface air conditioned room. The air exchange rate between the subsurface room and the exterior is kept to a minimum, to avoid large amounts of radon from outdoors to enter the subsurface room. The floor, the walls, and the ceiling of this subsurface room were painted with materials impermeable to radon gas. The access to the subsurface room is made from a larger entrance room through a tunnel plus a glass ante-room to decrease still further the air- exchange rate. The stainless steel hollow cylinder houses the sample to be measured and the detector. This cylinder can be filled with hyper pure nitrogen gas at a slighter positive pressure before counting a sample to prevent radon to enter the volume surrounding the detector. The low radon concentration near the detector minimizes the contribution of the 214 Bi photopeaks to the gamma spectra. The samples can be placed inside the cylinder in a variety of configurations. Spectra of selected gamma emitters were obtained with samples and detectors in several configurations. Gamma spectra were obtained for each of those configurations to illustrate the reduction the counting background. The reduction of gamma radiation background near the detector allows one to count naturally occurring radioactive materials (NORM

Platelet Counts in Insoluble Platelet-Rich Fibrin Clots: A Direct Method for Accurate Determination

Directory of Open Access Journals (Sweden)

Yutaka Kitamura

2018-02-01

Full Text Available Platelet-rich fibrin (PRF clots have been used in regenerative dentistry most often, with the assumption that growth factor levels are concentrated in proportion to the platelet concentration. Platelet counts in PRF are generally determined indirectly by platelet counting in other liquid fractions. This study shows a method for direct estimation of platelet counts in PRF. To validate this method by determination of the recovery rate, whole-blood samples were obtained with an anticoagulant from healthy donors, and platelet-rich plasma (PRP fractions were clotted with CaCl2 by centrifugation and digested with tissue-plasminogen activator. Platelet counts were estimated before clotting and after digestion using an automatic hemocytometer. The method was then tested on PRF clots. The quality of platelets was examined by scanning electron microscopy and flow cytometry. In PRP-derived fibrin matrices, the recovery rate of platelets and white blood cells was 91.6 and 74.6%, respectively, after 24 h of digestion. In PRF clots associated with small and large red thrombi, platelet counts were 92.6 and 67.2% of the respective total platelet counts. These findings suggest that our direct method is sufficient for estimating the number of platelets trapped in an insoluble fibrin matrix and for determining that platelets are distributed in PRF clots and red thrombi roughly in proportion to their individual volumes. Therefore, we propose this direct digestion method for more accurate estimation of platelet counts in most types of platelet-enriched fibrin matrix.

Gamma-spectrometric and total alpha-beta counting methods for radioactivity analysis of deuterium depleted water

International Nuclear Information System (INIS)

Ferdes, Ov. S.; Mladin, C.; Vladu, Mihaela; Bulubasa, G.; Bidica, N.

2008-01-01

According to national regulations, as well as to the EU directive on the quality of drinking water, the radionuclide concentrations represent some of the drinking water quality parameters. Among the most important radioactivity content parameters are: the total alpha and total beta concentration (Bq/l); K-40 content, and the gamma-nuclides volume activities. The paper presents the measuring methods for low-level total alpha and/or beta counting of volume samples, as well as the high-resolution gamma-ray spectrometric method used to measure the volume activity of nuclides in drinking water. These methods are applied to monitor the radioactivity content and quality of the QLARIVIA brand of Deuterium depleted water (DDW). There are discussed the performances of these applied methods as well as some preliminary results. (authors)

Association of BPD and IVH with early neutrophil and white counts in VLBW neonates with gestational age <32 weeks

Science.gov (United States)

Palta, Mari; Sadek-Badawi, Mona; Carlton, David P

2008-01-01

Objectives To investigate associations between early low neutrophil count from routine blood samples, white blood count (WBC), pregnancy complications and neonatal outcomes for very low birth weight infants (VLBW ≤1500g) with gestational age <32 weeks. Patients and Methods Information was abstracted on all infants admitted to level III NICUs in Wisconsin 2003-2004. 1002 (78%) had differential and corrected total white counts within 2 ½ hours of birth. Data analyses included frequency tables, binary logistic, ordinal logistc and ordinary regression. Results Low neutrophil count (<1000/μL) was strongly associated with low WBC, pregnancy complications and antenatal steroids. Low neutrophil count predicted bronchopulmonary dysplasia severity level (BPD) (OR: 1.7, 95% CI: 1.1-2.7) and intraventricular hemorrhage (IVH) grade (OR: 2.2, 95% CI: 1.3-3.8). Conclusions Early neutrophil counts may have multiple causes interfering with their routine use as an inflammatory marker. Nonetheless, low neutrophil count has consistent independent associations with outcomes. PMID:18563166

Division of methods for counting helminths’ eggs and the problem of efficiency of these methods

Directory of Open Access Journals (Sweden)

Katarzyna Jaromin-Gleń

2017-03-01

Full Text Available From the sanitary and epidemiological aspects, information concerning the developmental forms of intestinal parasites, especially the eggs of helminths present in our environment in: water, soil, sandpits, sewage sludge, crops watered with wastewater are very important. The methods described in the relevant literature may be classified in various ways, primarily according to the methodology of the preparation of samples from environmental matrices prepared for analysis, and the sole methods of counting and chambers/instruments used for this purpose. In addition, there is a possibility to perform the classification of the research methods analyzed from the aspect of the method and time of identification of the individuals counted, or the necessity for staining them. Standard methods for identification of helminths’ eggs from environmental matrices are usually characterized by low efficiency, i.e. from 30% to approximately 80%. The efficiency of the method applied may be measured in a dual way, either by using the method of internal standard or the ‘Split/Spike’ method. While measuring simultaneously in an examined object the efficiency of the method and the number of eggs, the ‘actual’ number of eggs may be calculated by multiplying the obtained value of the discovered eggs of helminths by inverse efficiency.

Liquid scintillation alpha counting and spectrometry and its application to bone and tissue samples

International Nuclear Information System (INIS)

McDowell, W.J.; Weiss, J.F.

1976-01-01

Three methods for determination of alpha-emitting nuclides using liquid scintillation counting are compared, and the pertinent literature is reviewed. Data showing the application of each method to the measurement of plutonium concentration in tissue and bone samples are presented. Counting with a commercial beta-liquid scintillation counter and an aqueous-phase-accepting scintillator is shown to be accurate only in cases where the alpha activity is high (several hundred counts/min or more), only gross alpha counting is desired, and beta-gamma emitters are known to be absent from the sample or present at low levels compared with the alpha activity. Counting with the same equipment and an aqueous immiscible scintillator containing an extractant for the nuclide of interest (extractive scintillator) is shown to allow better control of alpha peak shift due to quenching, a significant reduction of beta-gamma interference, and, usually, a low background. The desirability of using a multichannel pulse-height analyzer in the above two counting methods is stressed. The use of equipment and procedures designed for alpha liquid scintillation counting is shown to allow alpha spectrometry with an energy resolution capability of 200 to 300 keV full-peak-width-at-half-peak-height and a background of 0.3 to 1.0 counts/min, or as low as 0.01 counts/min if pulse-shape discrimination methods are used. Methods for preparing animal bone and tissue samples for assay are described

Low-cost digital counting interface for fermentation gas measurement

Energy Technology Data Exchange (ETDEWEB)

Erdman, M.D.; Deluiche, S.R.

1985-05-01

Laboratory- and pilot-scale volumetric measurement of fermentation gas can be readily determined with a standard wet-test gas meter. The initial cost of the meter, however, is quite prohibitive for experimental work and researchers have searched for other means of quantifying gas production. Techniques using calibrated floating gas holders, liquid displacement, flexible membranes, and conventional gas meters have been reported. Many of these methods lack a high degree of accuracy for small gas volumes. Residential gas meters such as those manufactured by Singer company, and others appear well suited for this application as long as a relatively dry gas is passed through the meter and a method is developed to subdivide the meter scale and record the results. The objective of this report was to construct a low cost, accurate, digital counting interface for concurrent operation with a low cost bellows-type gas meter. Although initially constructed for use in gas measurement studies, the interface can be used in other applications where digital output or computer interfacing are desired. 2 references.

Low Count Anomaly Detection at Large Standoff Distances

Science.gov (United States)

Pfund, David Michael; Jarman, Kenneth D.; Milbrath, Brian D.; Kiff, Scott D.; Sidor, Daniel E.

2010-02-01

Searching for hidden illicit sources of gamma radiation in an urban environment is difficult. Background radiation profiles are variable and cluttered with transient acquisitions from naturally occurring radioactive materials and medical isotopes. Potentially threatening sources likely will be nearly hidden in this noise and encountered at high standoff distances and low threat count rates. We discuss an anomaly detection algorithm that characterizes low count sources as threatening or non-threatening and operates well in the presence of high benign source variability. We discuss the algorithm parameters needed to reliably find sources both close to the detector and far away from it. These parameters include the cutoff frequencies of background tracking filters and the integration time of the spectrometer. This work is part of the development of the Standoff Radiation Imaging System (SORIS) as part of DNDO's Standoff Radiation Detection System Advanced Technology Demonstration (SORDS-ATD) program.

A new method of quench monitoring in liquid scintillation counting

International Nuclear Information System (INIS)

Horrocks, D.L.

1978-01-01

The quench level of different liquid scintillation counting samples is measured by comparing the responses (pulse heights) produced by the same energy electrons in each sample. The electrons utilized in the measurements are those of the maximum energy (Esub(max)) which are produced by the single Compton scattering process for the same energy gamma-rays in each sample. The Esub(max) response produced in any sample is related to the Esub(max) response produced in an unquenched, sealed standard. The difference in response on a logarithm response scale is defined as the ''H Number''. The H number is related to the counting efficiency of the desired radionuclide by measurement of a set of standards of known amounts of the radionuclide and different amounts of quench (standard quench curve). The concept of the H number has been shown to be theoretically valid. Based upon this proof, the features of the H number concept as embodied in the Beckman LS-8000 Series Liquid Scintillation Systems have been demonstrated. It has been shown that one H number is unique; it provides a method of instrument calibration and wide dynamic quench range measurements. Further, it has been demonstrated that the H number concept provides a universal quench parameter. Counting efficiency vs. H number plots are repeatable within the statistical limits of +-1% counting efficiency. By the use of the H number concept a very accurate method of automatic quench compensation (A.Q.C.) is possible. (T.G.)

Optimisation of liquid scintillation counting conditions to determine low activity levels of tritium and radiostrontium in aqueous solution

Energy Technology Data Exchange (ETDEWEB)

Rauret, Gemma; Mestres, J.S.; Ribera, Merce; Rajadel, Pilar (Barcelona Univ. (Spain). Dept. de Quimica Analitica)

1990-08-01

An optimisation of the counting conditions for the measurement of aqueous solutions of tritium or radiostrontium using Insta-Gel II as scintillator is presented. The variables optimised were the window, the ratio of mass of sample to mass of scintillator and the total volume of the counting mixture. An optimisation function which takes into account each of these variables, the background and also the efficiency is proposed. The conditions established allow the lowest possible detection limit to be reached. For tritium, this value was compared with that obtained when the standard method for water analysis was applied. (author).

Low gamma counting for measuring NORM/TENORM with a radon reducing system

Science.gov (United States)

Paschoa, Anselmo S.

2001-06-01

A detection system for counting low levels of gamma radiation was built by upgrading an existing rectangular chamber made of 18 metric tonne of steel fabricated before World War II. The internal walls, the ceiling, and the floor of the chamber are covered with copper sheets. The new detection system consists of a stainless steel hollow cylinder with variable circular apertures in the cylindrical wall and in the base, to allow introduction of a NaI (Tl) crystal, or alternatively, a HPGe detector in its interior. This counting system is mounted inside the larger chamber, which in turn is located in a subsurface air-conditioned room. The access to the subsurface room is made from a larger entrance room through a tunnel plus a glass anteroom to decrease the air-exchange rate. Both sample and detector are housed inside the stainless steel cylinder. This cylinder is filled with hyper pure nitrogen gas, before counting a sample, to prevent radon coming into contact with the detector surface. As a consequence, the contribution of the 214Bi photopeaks to the background gamma spectra is minimized. The reduction of the gamma radiation background near the detector facilitates measurement of naturally occurring radioactive materials (NORM), and/or technologically enhanced NORM (TENORM), which are usually at concentration levels only slightly higher than those typically found in the natural radioactive background.

Low gamma counting for measuring NORM/TENORM with a radon reducing system

International Nuclear Information System (INIS)

Paschoa, Anselmo S.

2001-01-01

A detection system for counting low levels of gamma radiation was built by upgrading an existing rectangular chamber made of 18 metric tonne of steel fabricated before World War II. The internal walls, the ceiling, and the floor of the chamber are covered with copper sheets. The new detection system consists of a stainless steel hollow cylinder with variable circular apertures in the cylindrical wall and in the base, to allow introduction of a NaI (Tl) crystal, or alternatively, a HPGe detector in its interior. This counting system is mounted inside the larger chamber, which in turn is located in a subsurface air-conditioned room. The access to the subsurface room is made from a larger entrance room through a tunnel plus a glass anteroom to decrease the air-exchange rate. Both sample and detector are housed inside the stainless steel cylinder. This cylinder is filled with hyper pure nitrogen gas, before counting a sample, to prevent radon coming into contact with the detector surface. As a consequence, the contribution of the 214 Bi photopeaks to the background gamma spectra is minimized. The reduction of the gamma radiation background near the detector facilitates measurement of naturally occurring radioactive materials (NORM), and/or technologically enhanced NORM (TENORM), which are usually at concentration levels only slightly higher than those typically found in the natural radioactive background. (author)

High sensitivity neutron activation analysis using coincidence counting method

International Nuclear Information System (INIS)

Suzuki, Shogo; Okada, Yukiko; Hirai, Shoji

1999-01-01

Four kinds of standard samples such as river sediment (NIES CRM No.16), Typical Japanese Diet, otoliths and river water were irradiated by TRIGA-II (100 kW, 3.7x10 12 n cm -2 s -1 ) for 6 h. After irradiation and cooling, they were analyzed by the coincidence counting method and a conventional γ-ray spectrometry. Se, Ba and Hf were determined by 75 Se 265 keV, 131 Ba 496 keV and 181 Hf 482 keV. On the river sediment sample, Ba and Hf showed the same values by two methods, but Se value contained Ta by the conventional method, although the coincidence counting method could analyze Se. On Typical Japanese Diet and otoliths, Se could be determined by two methods and Ba and Hf determined by the coincidence counting method but not determined by the conventional method. Se value in the river water agreed with the authorization value. (S.Y.)

New reactor safety circuit for low-power-level operation

International Nuclear Information System (INIS)

McDowell, W.P.; Keefe, D.J.; Rusch, G.K.

1978-01-01

In the operation of nuclear reactors at low-power levels, one of the primary instrumentation problems is that the statistical fluctuations of reactor neutron population are accentuated by conventional log-count-rate and differentiating circuits and can cause frequent spurious scrams unless long time constants are incorporated in the circuit. Excessive time constants may introduce undesirable delay in the circuit response to legitimate scram signals. The paper develops the concept of a count doubling-time monitor which generates a scram signal if the number of counts from a pulse type neutron detector doubles in a given period of time. The paper demonstrates the theoretical relation between count doubling time and asymptomatic periods. A practical circuit to implement the function is described

Determination of Np, Pu and Am in high level radioactive waste with extraction-liquid scintillation counting

International Nuclear Information System (INIS)

Yang Dazhu; Zhu Yongjun; Jiao Rongzhou

1994-01-01

A new method for the determination of transuranium elements, Np, Pu and Am with extraction-liquid scintillation counting has been studied systematically. Procedures for the separation of Pu and Am by HDEHP-TRPO extraction and for the separation of Np by TTA-TiOA extraction have been developed, by which the recovery of Np, Pu and Am is 97%, 99% and 99%, respectively, and the decontamination factors for the major fission products ( 90 Sr, 137 Cs etc.) are 10 4 -10 6 . Pulse shape discrimination (PSD) technique has been introduced to liquid scintillation counting, by which the counting efficiency of α-activity is >99% and the rejection of β-counts is >99.95%. This new method, combining extraction and pulse shape discrimination with liquid scintillation technique, has been successfully applied to the assay of Np, Pu and Am in high level radioactive waste. (author) 7 refs.; 7 figs.; 4 tabs

Low level alpha activity measurements with pulse shape discrimination

International Nuclear Information System (INIS)

Noguchi, Masayasu; Satoh, Kaneaki; Higuchi, Hideo.

1984-01-01

Pulse shape discrimination of α and β rays with liquid scintillation counting was investigated for the purpose of low level α activity measurements. Various liquid scintillators for pulse shape discrimination were examined by means of pulse rise time analysis. A new scintillator of low cost and of superior characteristics was found. The figure of merits better than 3.5 in risetime spectrum and the energy resolution better than 9% were obtained for carefully prepared samples. The background counting rate for a sample of 10 ml was reduced to 0.013 cpm/MeV in the range of α ray energy 5 to 7 MeV. (author)

Correction to the count-rate detection limit and sample/blank time-allocation methods

International Nuclear Information System (INIS)

Alvarez, Joseph L.

2013-01-01

A common form of count-rate detection limits contains a propagation of uncertainty error. This error originated in methods to minimize uncertainty in the subtraction of the blank counts from the gross sample counts by allocation of blank and sample counting times. Correct uncertainty propagation showed that the time allocation equations have no solution. This publication presents the correct form of count-rate detection limits. -- Highlights: •The paper demonstrated a proper method of propagating uncertainty of count rate differences. •The standard count-rate detection limits were in error. •Count-time allocation methods for minimum uncertainty were in error. •The paper presented the correct form of the count-rate detection limit. •The paper discussed the confusion between count-rate uncertainty and count uncertainty

A Field Evaluation of the Time-of-Detection Method to Estimate Population Size and Density for Aural Avian Point Counts

Directory of Open Access Journals (Sweden)

Mathew W. Alldredge

2007-12-01

Full Text Available The time-of-detection method for aural avian point counts is a new method of estimating abundance, allowing for uncertain probability of detection. The method has been specifically designed to allow for variation in singing rates of birds. It involves dividing the time interval of the point count into several subintervals and recording the detection history of the subintervals when each bird sings. The method can be viewed as generating data equivalent to closed capture-recapture information. The method is different from the distance and multiple-observer methods in that it is not required that all the birds sing during the point count. As this method is new and there is some concern as to how well individual birds can be followed, we carried out a field test of the method using simulated known populations of singing birds, using a laptop computer to send signals to audio stations distributed around a point. The system mimics actual aural avian point counts, but also allows us to know the size and spatial distribution of the populations we are sampling. Fifty 8-min point counts (broken into four 2-min intervals using eight species of birds were simulated. Singing rate of an individual bird of a species was simulated following a Markovian process (singing bouts followed by periods of silence, which we felt was more realistic than a truly random process. The main emphasis of our paper is to compare results from species singing at (high and low homogenous rates per interval with those singing at (high and low heterogeneous rates. Population size was estimated accurately for the species simulated, with a high homogeneous probability of singing. Populations of simulated species with lower but homogeneous singing probabilities were somewhat underestimated. Populations of species simulated with heterogeneous singing probabilities were substantially underestimated. Underestimation was caused by both the very low detection probabilities of all distant

Standardization of 241Am by digital coincidence counting, liquid scintillation counting and defined solid angle counting

International Nuclear Information System (INIS)

Balpardo, C.; Capoulat, M.E.; Rodrigues, D.; Arenillas, P.

2010-01-01

The nuclide 241 Am decays by alpha emission to 237 Np. Most of the decays (84.6%) populate the excited level of 237 Np with energy of 59.54 keV. Digital coincidence counting was applied to standardize a solution of 241 Am by alpha-gamma coincidence counting with efficiency extrapolation. Electronic discrimination was implemented with a pressurized proportional counter and the results were compared with two other independent techniques: Liquid scintillation counting using the logical sum of double coincidences in a TDCR array and defined solid angle counting taking into account activity inhomogeneity in the active deposit. The results show consistency between the three methods within a limit of a 0.3%. An ampoule of this solution will be sent to the International Reference System (SIR) during 2009. Uncertainties were analysed and compared in detail for the three applied methods.

Bayesian approach in MN low dose of radiation counting

International Nuclear Information System (INIS)

Serna Berna, A.; Alcaraz, M.; Acevedo, C.; Navarro, J. L.; Alcanzar, M. D.; Canteras, M.

2006-01-01

The Micronucleus assay in lymphocytes is a well established technique for the assessment of genetic damage induced by ionizing radiation. Due to the presence of a natural background of MN the net MN is obtained by subtracting this value to the gross value. When very low doses of radiation are given the induced MN is close even lower than the predetermined background value. Furthermore, the damage distribution induced by the radiation follows a Poisson probability distribution. These two facts pose a difficult task to obtain the net counting rate in the exposed situations. It is possible to overcome this problem using a bayesian approach, in which the selection of a priori distributions for the background and net counting rate plays an important role. In the present work we make a detailed analysed using bayesian theory to infer the net counting rate in two different situations: a) when the background is known for an individual sample, using exact value value for the background and Jeffreys prior for the net counting rate, and b) when the background is not known and we make use of a population background distribution as background prior function and constant prior for the net counting rate. (Author)

Determination of confidence limits for experiments with low numbers of counts

International Nuclear Information System (INIS)

Kraft, R.P.; Burrows, D.N.; Nousek, J.A.

1991-01-01

Two different methods, classical and Bayesian, for determining confidence intervals involving Poisson-distributed data are compared. Particular consideration is given to cases where the number of counts observed is small and is comparable to the mean number of background counts. Reasons for preferring the Bayesian over the classical method are given. Tables of confidence limits calculated by the Bayesian method are provided for quick reference. 12 refs

An improved method for 85Kr analysis by liquid scintillation counting and its application to atmospheric 85Kr determination

International Nuclear Information System (INIS)

Momoshima, Noriyuki; Inoue, Fumio; Sugihara, Shinji; Shimada, Jun; Taniguchi, Makoto

2010-01-01

Atmospheric 85 Kr concentration at Fukuoka, Japan was determined by an improved 85 Kr analytical method using liquid scintillation counting (LSC). An average value of 1.54 ± 0.05 Bq m -3 was observed in 2008, which is about two times that measured in 1981 at Fukuoka, indicating a 29 mBq y -1 rate of increase as an average for these 27 years. The analytical method developed involves collecting Kr from air using activated charcoal at liquid N 2 temperature and purifying it using He at dry ice temperature, followed by Kr separation by gas chromatography. An overall Kr recovery of 76.4 ± 8.1% was achieved when Kr was analyzed in 500-1000 l of air. The Kr isolated by gas chromatography was collected on silica gel in a quartz glass vial cooled to liquid N 2 temperature and the activity of 85 Kr was measured with a low-background LS counter. The detection limit of 85 Kr activity by the present analytical method is 0.0015 Bq at a 95% confidence level, including all propagation errors, which is equivalent with 85 Kr in 1.3 l of the present air under the analytical conditions of 72.1% counting efficiency, 0.1597 cps background count rate, and 76.4% Kr recovery.

Multi-level methods and approximating distribution functions

International Nuclear Information System (INIS)

Wilson, D.; Baker, R. E.

2016-01-01

Biochemical reaction networks are often modelled using discrete-state, continuous-time Markov chains. System statistics of these Markov chains usually cannot be calculated analytically and therefore estimates must be generated via simulation techniques. There is a well documented class of simulation techniques known as exact stochastic simulation algorithms, an example of which is Gillespie’s direct method. These algorithms often come with high computational costs, therefore approximate stochastic simulation algorithms such as the tau-leap method are used. However, in order to minimise the bias in the estimates generated using them, a relatively small value of tau is needed, rendering the computational costs comparable to Gillespie’s direct method. The multi-level Monte Carlo method (Anderson and Higham, Multiscale Model. Simul. 10:146–179, 2012) provides a reduction in computational costs whilst minimising or even eliminating the bias in the estimates of system statistics. This is achieved by first crudely approximating required statistics with many sample paths of low accuracy. Then correction terms are added until a required level of accuracy is reached. Recent literature has primarily focussed on implementing the multi-level method efficiently to estimate a single system statistic. However, it is clearly also of interest to be able to approximate entire probability distributions of species counts. We present two novel methods that combine known techniques for distribution reconstruction with the multi-level method. We demonstrate the potential of our methods using a number of examples.

Multi-level methods and approximating distribution functions

Energy Technology Data Exchange (ETDEWEB)

Wilson, D., E-mail: daniel.wilson@dtc.ox.ac.uk; Baker, R. E. [Mathematical Institute, University of Oxford, Radcliffe Observatory Quarter, Woodstock Road, Oxford, OX2 6GG (United Kingdom)

2016-07-15

Biochemical reaction networks are often modelled using discrete-state, continuous-time Markov chains. System statistics of these Markov chains usually cannot be calculated analytically and therefore estimates must be generated via simulation techniques. There is a well documented class of simulation techniques known as exact stochastic simulation algorithms, an example of which is Gillespie’s direct method. These algorithms often come with high computational costs, therefore approximate stochastic simulation algorithms such as the tau-leap method are used. However, in order to minimise the bias in the estimates generated using them, a relatively small value of tau is needed, rendering the computational costs comparable to Gillespie’s direct method. The multi-level Monte Carlo method (Anderson and Higham, Multiscale Model. Simul. 10:146–179, 2012) provides a reduction in computational costs whilst minimising or even eliminating the bias in the estimates of system statistics. This is achieved by first crudely approximating required statistics with many sample paths of low accuracy. Then correction terms are added until a required level of accuracy is reached. Recent literature has primarily focussed on implementing the multi-level method efficiently to estimate a single system statistic. However, it is clearly also of interest to be able to approximate entire probability distributions of species counts. We present two novel methods that combine known techniques for distribution reconstruction with the multi-level method. We demonstrate the potential of our methods using a number of examples.

Proposals of counting method for bubble detectors and their intercomparisons

International Nuclear Information System (INIS)

Ramalho, Eduardo; Silva, Ademir X.; Bellido, Luis F.; Facure, Alessandro; Pereira, Mario

2009-01-01

The study of neutron's spectrometry and dosimetry has become significantly easier due to relatively new devices called bubble detectors. Insensitive to gamma rays and composed by superheated emulsions, they still are subjects of many researches in Radiation Physics and Nuclear Engineering. In bubble detectors, either exposed to more intense neutron fields or for a long time, when more bubbles are produced, the statistical uncertainty during the dosimetric and spectrometric processes is reduced. A proposal of this nature is set up in this work, which presents ways to perform counting processes for bubble detectors and an updated proceeding to get the irradiated detectors' images in order to make the manual counting easier. Twelve BDS detectors were irradiated by RDS111 cyclotron from IEN's (Instituto de Engenharia Nuclear) and photographed using an assembly specially designed for this experiment. Counting was proceeded manually in a first moment; simultaneously, ImagePro was used in order to perform counting automatically. The bubble counting values, either manual or automatic, were compared and the time to get them and their difficult levels as well. After the bubble counting, the detectors' standardizes responses were calculated in both cases, according to BDS's manual and they were also compared. Among the results, the counting on these devices really becomes very hard at a large number of bubbles, besides higher variations in counting of many bubbles. Because of the good agreement between manual counting and the custom program, the last one revealed a good alternative in practical and economical levels. Despite the good results, the custom program needs of more adjustments in order to achieve more accuracy on higher counting on bubble detectors for neutron measurement applications. (author)

Low-level liquid scitillation counting for quantification of annual {sup 3}H and {sup 14}C concentrations in tree disks

Energy Technology Data Exchange (ETDEWEB)

Kopka, B [Goettingen Univ. (Germany). Isotopenlaboratorium fuer Biologische und Medizinische Forschung; Schikowski, J [Goettingen Univ. (Germany). Isotopenlaboratorium fuer Biologische und Medizinische Forschung; Porstendoerfer, J [Goettingen Univ. (Germany). Isotopenlaboratorium fuer Biologische und Medizinische Forschung

1997-03-01

The government of Schleswig Holstein funded a study to perform the retrospective determination of airborne {sup 3}H and {sup 14}C concentrations. It is well known, that in tree rings most of the hydrogen and cabron is fixed after insertion in the matrix of wood and that the radionuclide concentration correlates with former airborne activity concentrations. For the retrospective study wood disks of trees located in the region near the nuclear power plant of Kruemmel and control disks of unsuspected areas were selected. The hydrogen of the wood was transformed to water and the carbon to carbondioxide by classical oxidation processes (combustion in a furnace). The contents of {sup 3}H in the water and {sup 14}C of the carbondioxide (solved in scintillation liquid) were determined by liquid scintillation counting, using a low-level counter (type Quantulus 1220, Wallac). (orig.)

Combining predictive microbiology with cold-enrichment in minced pork for quantifying low levels of Salmonella Typhimurium DT104

DEFF Research Database (Denmark)

Møller, C. O. A.; Aabo, Søren; Hansen, Tina Beck

2013-01-01

underestimation of the Salmonella count after enrichment. Whether competition between these species also took place in the meat during enrichment is not known. However, as the observed levels of the competitive species were below 5.5 log10-units it is questionable whether interaction with S. Typhimurium DT104......OBJECTIVE For determination of Salmonella concentration in meat various methods can be used depending on the expected level. When higher levels (102 to 103 bacteria or more per g) are anticipated, plate count techniques using selective agars, i.e. XLD, are appropriate whereas for low numbers (3......, the objective of this study was to evaluate the possibility to carry out a Salmonella enrichment step in the meat itself and use the two species interaction model, presented by Møller et al. (2013), for quantifying levels of Salmonella Typhimurium DT104 in minced pork. METHODS A total number of 101 minced pork...

A Method for Counting Moving People in Video Surveillance Videos

Directory of Open Access Journals (Sweden)

Mario Vento

2010-01-01

Full Text Available People counting is an important problem in video surveillance applications. This problem has been faced either by trying to detect people in the scene and then counting them or by establishing a mapping between some scene feature and the number of people (avoiding the complex detection problem. This paper presents a novel method, following this second approach, that is based on the use of SURF features and of an ϵ-SVR regressor provide an estimate of this count. The algorithm takes specifically into account problems due to partial occlusions and to perspective. In the experimental evaluation, the proposed method has been compared with the algorithm by Albiol et al., winner of the PETS 2009 contest on people counting, using the same PETS 2009 database. The provided results confirm that the proposed method yields an improved accuracy, while retaining the robustness of Albiol's algorithm.

A Method for Counting Moving People in Video Surveillance Videos

Directory of Open Access Journals (Sweden)

Conte Donatello

2010-01-01

Full Text Available People counting is an important problem in video surveillance applications. This problem has been faced either by trying to detect people in the scene and then counting them or by establishing a mapping between some scene feature and the number of people (avoiding the complex detection problem. This paper presents a novel method, following this second approach, that is based on the use of SURF features and of an -SVR regressor provide an estimate of this count. The algorithm takes specifically into account problems due to partial occlusions and to perspective. In the experimental evaluation, the proposed method has been compared with the algorithm by Albiol et al., winner of the PETS 2009 contest on people counting, using the same PETS 2009 database. The provided results confirm that the proposed method yields an improved accuracy, while retaining the robustness of Albiol's algorithm.

A Method for Counting Moving People in Video Surveillance Videos

Science.gov (United States)

Conte, Donatello; Foggia, Pasquale; Percannella, Gennaro; Tufano, Francesco; Vento, Mario

2010-12-01

People counting is an important problem in video surveillance applications. This problem has been faced either by trying to detect people in the scene and then counting them or by establishing a mapping between some scene feature and the number of people (avoiding the complex detection problem). This paper presents a novel method, following this second approach, that is based on the use of SURF features and of an [InlineEquation not available: see fulltext.]-SVR regressor provide an estimate of this count. The algorithm takes specifically into account problems due to partial occlusions and to perspective. In the experimental evaluation, the proposed method has been compared with the algorithm by Albiol et al., winner of the PETS 2009 contest on people counting, using the same PETS 2009 database. The provided results confirm that the proposed method yields an improved accuracy, while retaining the robustness of Albiol's algorithm.

The use of regression analysis in determining reference intervals for low hematocrit and thrombocyte count in multiple electrode aggregometry and platelet function analyzer 100 testing of platelet function.

Science.gov (United States)

Kuiper, Gerhardus J A J M; Houben, Rik; Wetzels, Rick J H; Verhezen, Paul W M; Oerle, Rene van; Ten Cate, Hugo; Henskens, Yvonne M C; Lancé, Marcus D

2017-11-01

Low platelet counts and hematocrit levels hinder whole blood point-of-care testing of platelet function. Thus far, no reference ranges for MEA (multiple electrode aggregometry) and PFA-100 (platelet function analyzer 100) devices exist for low ranges. Through dilution methods of volunteer whole blood, platelet function at low ranges of platelet count and hematocrit levels was assessed on MEA for four agonists and for PFA-100 in two cartridges. Using (multiple) regression analysis, 95% reference intervals were computed for these low ranges. Low platelet counts affected MEA in a positive correlation (all agonists showed r 2 ≥ 0.75) and PFA-100 in an inverse correlation (closure times were prolonged with lower platelet counts). Lowered hematocrit did not affect MEA testing, except for arachidonic acid activation (ASPI), which showed a weak positive correlation (r 2 = 0.14). Closure time on PFA-100 testing was inversely correlated with hematocrit for both cartridges. Regression analysis revealed different 95% reference intervals in comparison with originally established intervals for both MEA and PFA-100 in low platelet or hematocrit conditions. Multiple regression analysis of ASPI and both tests on the PFA-100 for combined low platelet and hematocrit conditions revealed that only PFA-100 testing should be adjusted for both thrombocytopenia and anemia. 95% reference intervals were calculated using multiple regression analysis. However, coefficients of determination of PFA-100 were poor, and some variance remained unexplained. Thus, in this pilot study using (multiple) regression analysis, we could establish reference intervals of platelet function in anemia and thrombocytopenia conditions on PFA-100 and in thrombocytopenia conditions on MEA.

Use of sum-peak and coincidence counting methods for activity standardization of {sup 22}Na

Energy Technology Data Exchange (ETDEWEB)

Oliveira, E.M. de, E-mail: estela@ird.gov.br [Laboratorio Nacional de Metrologia das Radiacoes Ionizantes (LNMRI/IRD/CNEN), Av. Salvador Allende, s/n, Recreio, CEP 22780-160 Rio de Janeiro (Brazil); Iwahara, A.; Poledna, R. [Laboratorio Nacional de Metrologia das Radiacoes Ionizantes (LNMRI/IRD/CNEN), Av. Salvador Allende, s/n, Recreio, CEP 22780-160 Rio de Janeiro (Brazil); Silva, M.A.L. da [Coordenacao Geral de Instalacoes Nucleares/Comissao Nacional de Energia Nuclear, R. Gal. Severiano, 90 - Botafogo, CEP 22290-901 Rio de Janeiro (Brazil); Tauhata, L. [Fundacao Carlos Chagas Filho de Amparo a Pesquisa do Estado do Rio de Janeiro (FAPERJ), Av. Erasmo Braga, 118-6 Degree-Sign andar, CEP 20020-000 Centro, Rio de Janeiro (Brazil); Delgado, J.U. [Laboratorio Nacional de Metrologia das Radiacoes Ionizantes (LNMRI/IRD/CNEN), Av. Salvador Allende, s/n, Recreio, CEP 22780-160 Rio de Janeiro (Brazil); Lopes, R.T. [Laboratorio de Instrumentacao Nuclear (LIN/PEN/COPPE/UFRJ), Caixa Postal 68509, CEP 21945-970 Rio de Janeiro (Brazil)

2012-09-21

A solution containing the positron emitter {sup 22}Na has been absolutely standardized using the 4{pi}{beta}-{gamma} coincidence counting method and the sum-peak spectrometry counting method. In the 4{pi}{beta}-{gamma} coincidence method two ways for the activity concentration measurements were used: gating on the 1275 keV photopeak and on the 1786 keV sum-peak where the knowledge of the {beta}{sup +}-branching ratio is required. In the sum-peak method the measurements were carried out using three experimental arrangements: the first composed by a well type 5 in. Multiplication-Sign 5 in. NaI(Tl) scintillation crystal, the second by a 3 in. Multiplication-Sign 3 in. NaI(Tl) scintillation crystal placed on the top of the first, resulting in a 4{pi} counting geometry and the third arrangement is a high purity coaxial germanium detector. The results that are obtained by these two methods are compatible within the standard uncertainty values with a coverage factor of k=2 ({approx}95% of the confidence level). This means that the sum-peak counting with its more simple experimental setup than the complex coincidence 4{pi}{beta}-{gamma} counting system gives consistent results for the activity standardization of {sup 22}Na with smaller uncertainties. Besides, the time period involved to attain the result of the standardization was quite shorter than the coincidence measurements used in this work.

Enteric parasitic infections in HIV-infected patients with low CD4 counts in Toto, Nigeria

International Nuclear Information System (INIS)

Abaver, D.T.; Nwobegahay, J.M.; Goon, D.T.; Khoza, L.B

2012-01-01

Objectives: Enteric parasites are a major cause of diarrhoea in HIV/AIDS patients with low CD4 counts. Parasitic infections in HIV-infected individuals can reduce their quality of life and life span, especially those who are severely immunosuppressed with a CD4 T-lymphocyte count 0.05). Conclusions: Low CD4 counts in HIV-infected patients can lead to enteric infections. This information strengthens the importance of monitoring CD4 counts and intestinal parasites. Routine CD4 testing will greatly improve the prognosis of HIV positive patients. (author)

Determination of the thoron daughter working level by a one gross alpha-count

International Nuclear Information System (INIS)

Bigu, J.; Lau, W.K.

1983-02-01

A study has been done on the determination of the thoron daughter Working Level, WL(Tn), by a one gross α-count. The relationship between the gross α-count rate per unit of volume of air sampled and WL(Tn), denoted the F-factor, has been investigated as a function of sampling time, elapsed time from the end of the sampling period, i.e., waiting time, and the thoron daughter disequilibrium ratio [ThC]/[ThB]. It has been found that F depends on both the waiting time and [ThC]/[ThB]. If α-count measurements are made at least 300 min after the end of sampling, F changes by less than 10 percent over the full range of theoretical values of [ThC]/[ThB], i.e., from 0 to 1. The F-factor is independent of [ThC]/[ThB] at approximately 215 min after the end of sampling. This feature can be used to determine WL(Tn) with higher accuracy and at least 1.5 hr earlier than is commonly done using other one gross α-count methods reported in the literature

Standardization of {sup 241}Am by digital coincidence counting, liquid scintillation counting and defined solid angle counting

Energy Technology Data Exchange (ETDEWEB)

Balpardo, C., E-mail: balpardo@cae.cnea.gov.a [Laboratorio de Metrologia de Radioisotopos, CNEA, Buenos Aires (Argentina); Capoulat, M.E.; Rodrigues, D.; Arenillas, P. [Laboratorio de Metrologia de Radioisotopos, CNEA, Buenos Aires (Argentina)

2010-07-15

The nuclide {sup 241}Am decays by alpha emission to {sup 237}Np. Most of the decays (84.6%) populate the excited level of {sup 237}Np with energy of 59.54 keV. Digital coincidence counting was applied to standardize a solution of {sup 241}Am by alpha-gamma coincidence counting with efficiency extrapolation. Electronic discrimination was implemented with a pressurized proportional counter and the results were compared with two other independent techniques: Liquid scintillation counting using the logical sum of double coincidences in a TDCR array and defined solid angle counting taking into account activity inhomogeneity in the active deposit. The results show consistency between the three methods within a limit of a 0.3%. An ampoule of this solution will be sent to the International Reference System (SIR) during 2009. Uncertainties were analysed and compared in detail for the three applied methods.

A high count rate position decoding and energy measuring method for nuclear cameras using Anger logic detectors

International Nuclear Information System (INIS)

Wong, W.H.; Li, H.; Uribe, J.

1998-01-01

A new method for processing signals from Anger position-sensitive detectors used in gamma cameras and PET is proposed for very high count-rate imaging where multiple-event pileups are the norm. This method is designed to sort out and recover every impinging event from multiple-event pileups while maximizing the collection of scintillation signal for every event to achieve optimal accuracy in the measurement of energy and position. For every detected event, this method cancels the remnant signals from previous events, and excludes the pileup of signals from following events. The remnant subtraction is exact even for multiple pileup events. A prototype circuit for energy recovery demonstrated that the maximum count rates can be increased by more than 10 times comparing to the pulse-shaping method, and the energy resolution is as good as pulse shaping (or fixed integration) at low count rates. At 2 x 10 6 events/sec on NaI(Tl), the true counts acquired with this method is 3.3 times more than the delay-line clipping method (256 ns clipping) due to events recovered from pileups. Pulse-height spectra up to 3.5 x 10 6 events/sec have been studied. Monte Carlo simulation studies have been performed for image-quality comparisons between different processing methods

Performance of 3DOSEM and MAP algorithms for reconstructing low count SPECT acquisitions

Energy Technology Data Exchange (ETDEWEB)

Grootjans, Willem [Radboud Univ. Medical Center, Nijmegen (Netherlands). Dept. of Radiology and Nuclear Medicine; Leiden Univ. Medical Center (Netherlands). Dept. of Radiology; Meeuwis, Antoi P.W.; Gotthardt, Martin; Visser, Eric P. [Radboud Univ. Medical Center, Nijmegen (Netherlands). Dept. of Radiology and Nuclear Medicine; Slump, Cornelis H. [Univ. Twente, Enschede (Netherlands). MIRA Inst. for Biomedical Technology and Technical Medicine; Geus-Oei, Lioe-Fee de [Radboud Univ. Medical Center, Nijmegen (Netherlands). Dept. of Radiology and Nuclear Medicine; Univ. Twente, Enschede (Netherlands). MIRA Inst. for Biomedical Technology and Technical Medicine; Leiden Univ. Medical Center (Netherlands). Dept. of Radiology

2016-07-01

Low count single photon emission computed tomography (SPECT) is becoming more important in view of whole body SPECT and reduction of radiation dose. In this study, we investigated the performance of several 3D ordered subset expectation maximization (3DOSEM) and maximum a posteriori (MAP) algorithms for reconstructing low count SPECT images. Phantom experiments were conducted using the National Electrical Manufacturers Association (NEMA) NU2 image quality (IQ) phantom. The background compartment of the phantom was filled with varying concentrations of pertechnetate and indiumchloride, simulating various clinical imaging conditions. Images were acquired using a hybrid SPECT/CT scanner and reconstructed with 3DOSEM and MAP reconstruction algorithms implemented in Siemens Syngo MI.SPECT (Flash3D) and Hermes Hybrid Recon Oncology (Hyrid Recon 3DOSEM and MAP). Image analysis was performed by calculating the contrast recovery coefficient (CRC),percentage background variability (N%), and contrast-to-noise ratio (CNR), defined as the ratio between CRC and N%. Furthermore, image distortion is characterized by calculating the aspect ratio (AR) of ellipses fitted to the hot spheres. Additionally, the performance of these algorithms to reconstruct clinical images was investigated. Images reconstructed with 3DOSEM algorithms demonstrated superior image quality in terms of contrast and resolution recovery when compared to images reconstructed with filtered-back-projection (FBP), OSEM and 2DOSEM. However, occurrence of correlated noise patterns and image distortions significantly deteriorated the quality of 3DOSEM reconstructed images. The mean AR for the 37, 28, 22, and 17 mm spheres was 1.3, 1.3, 1.6, and 1.7 respectively. The mean N% increase in high and low count Flash3D and Hybrid Recon 3DOSEM from 5.9% and 4.0% to 11.1% and 9.0%, respectively. Similarly, the mean CNR decreased in high and low count Flash3D and Hybrid Recon 3DOSEM from 8.7 and 8.8 to 3.6 and 4

Inferior clinical outcome of the CD4+ cell count-guided antiretroviral treatment interruption strategy in the SMART study: role of CD4+ Cell counts and HIV RNA levels during follow-up

DEFF Research Database (Denmark)

Lundgren, Jens; Babiker, Abdel; El-Sadr, Wafaa

2008-01-01

BACKGROUND AND METHODS: The SMART study compared 2 strategies for using antiretroviral therapy-drug conservation (DC) and viral suppression (VS)-in 5,472 human immunodeficiency virus (HIV)-infected patients with CD4+ cell counts >350 cells/microL. Rates and predictors of opportunistic disease...... or death (OD/death) and the relative risk (RR) in DC versus VS groups according to the latest CD4+ cell count and HIV RNA level are reported. RESULTS: During a mean of 16 months of follow-up, DC patients spent more time with a latest CD4+ cell count ...%) and with a latest HIV RNA level >400 copies/mL (71% vs. 28%) and had a higher rate of OD/death (3.4 vs. 1.3/100 person-years) than VS patients. For periods of follow- up with a CD4+ cell count

Intercomparison test for the determination of low-level tritium activities in natural waters for age dating purposes

International Nuclear Information System (INIS)

Mohokar, Hemant; Diksha; Sinha, U.K.; Joseph, T.B.

2015-01-01

A world-wide inter-comparison was undertaken to assess the quality of 3 H data produced by laboratories worldwide, primarily aimed at those conducting groundwater age dating applications in hydrogeology. These low-level tritium test samples encompass 3 H concentrations currently observed in modern precipitation, surface and ground waters, whereupon each participating laboratory employed routine pre-treatment or electrolytic enrichment procedures and 3 H counting methods. The test water samples were comprised of one tritium-free water and seven water samples. Fifty-eight laboratories reported test data to the IAEA for all, or a sub-set, of the eight test samples. The method applied by our laboratory was electrolytic enrichment followed by counting in liquid scintillation counter

A Low Level Radioactivity Monitor for Aqueous Waste

International Nuclear Information System (INIS)

Quirk, E.J.M.

1968-04-01

A system is described for continuous monitoring of very low levels of radioactivity in waste water containing typically 3.5 g/l dissolved solids. Spray evaporation of the water enables the dissolved solids to be recovered in the form of an aerosol and collected on a filter tape where the radioactivity is measured by a radiation detector. The advantage of this method compared with a direct measurement is that the attenuating effect of the water is removed and thus greater sensitivity is obtained. Compensation for background and any contamination is achieved by feeding distilled water to the aerosol generator every alternate sampling period and recording the count difference between two successive sampling periods . A printed record of the totalised count difference is obtained once per hour during the integration time of one month. For β radioactivity the minimum values of specific activity measurable extend from 1 x 10 -6 Ci/m 3 to 6 x 10 -8 Ci/m depending on the B end-point energy in the range 167 KeV to 2.26 MeV. The estimated minimum measurable specific activity is 6 x 10 -8 Ci/m 3

A Low Level Radioactivity Monitor for Aqueous Waste

Energy Technology Data Exchange (ETDEWEB)

Quirk, E J.M.

1968-04-15

A system is described for continuous monitoring of very low levels of radioactivity in waste water containing typically 3.5 g/l dissolved solids. Spray evaporation of the water enables the dissolved solids to be recovered in the form of an aerosol and collected on a filter tape where the radioactivity is measured by a radiation detector. The advantage of this method compared with a direct measurement is that the attenuating effect of the water is removed and thus greater sensitivity is obtained. Compensation for background and any contamination is achieved by feeding distilled water to the aerosol generator every alternate sampling period and recording the count difference between two successive sampling periods . A printed record of the totalised count difference is obtained once per hour during the integration time of one month. For {beta} radioactivity the minimum values of specific activity measurable extend from 1 x 10{sup -6} Ci/m{sup 3} to 6 x 10{sup -8} Ci/m depending on the B end-point energy in the range 167 KeV to 2.26 MeV. The estimated minimum measurable specific activity is 6 x 10{sup -8} Ci/m{sup 3}.

Low-level Radioactive waste Management

International Nuclear Information System (INIS)

1991-01-01

This meeting describes low-level radioactive waste management problems and contains 8 papers: 1 Low-level radioactive waste management: exemption concept and criteria used by international organizations. 2 Low-level radioactive waste management: french and foreign regulations 3 Low-level radioactive waste management in EDF nuclear power plants (FRANCE) 4 Low-level radioactive waste management in COGEMA (FRANCE) 5 Importance of low-level radioactive wastes in dismantling strategy in CEA (FRANCE) 6 Low-level radioactive waste management in hospitals 7 Low-level radioactive waste disposal: radiation protection laws 8 Methods of low-level radioactive materials measurements during reactor dismantling or nuclear facilities demolition (FRANCE)

Prevalence of Low Sperm Count and Abnormal Semen Parameters ...

African Journals Online (AJOL)

elearning

In order to provide an insight to the prevalence of low sperm count and abnormal semen ... function based on its poor prediction of fertility ... consecutively consenting male partners of women ... Interestingly, 30 (25%) of the semen from 21-30 ... Percentage. Normospermia. = 20.0. 45. 26. Oligospermia. < 10.0. 118. 70.

Investigation on Carbohydrate Counting Method in Type 1 Diabetic Patients

Directory of Open Access Journals (Sweden)

Osman Son

2014-01-01

Full Text Available Objective. The results from Diabetes Control and Complications Trial (DCCT have propounded the importance of the approach of treatment by medical nutrition when treating diabetes mellitus (DM. During this study, we tried to inquire carbohydrate (Kh count method’s positive effects on the type 1 DM treatment’s success as well as on the life quality of the patients. Methods. 22 of 37 type 1 DM patients who applied to Eskişehir Osmangazi University, Faculty of Medicine Hospital, Department of Endocrinology and Metabolism, had been treated by Kh count method and 15 of them are treated by multiple dosage intensive insulin treatment with applying standard diabetic diet as a control group and both of groups were under close follow-up for 6 months. Required approval was taken from the Ethical Committee of Eskişehir Osmangazi University, Medical Faculty, as well as informed consent from the patients. The body weight of patients who are treated by carbohydrate count method and multiple dosage intensive insulin treatment during the study beginning and after 6-month term, body mass index, and body compositions are analyzed. A short life quality and medical research survey applied. At statistical analysis, t-test, chi-squared test, and Mann-Whitney U test were used. Results. There had been no significant change determined at glycemic control indicators between the Kh counting group and the standard diabetic diet and multiple dosage insulin treatment group in our study. Conclusion. As a result, Kh counting method which offers a flexible nutrition plan to diabetic individuals is a functional method.

Current automated 3D cell detection methods are not a suitable replacement for manual stereologic cell counting

Directory of Open Access Journals (Sweden)

Christoph eSchmitz

2014-05-01

Full Text Available Stereologic cell counting has had a major impact on the field of neuroscience. A major bottleneck in stereologic cell counting is that the user must manually decide whether or not each cell is counted according to three-dimensional (3D stereologic counting rules by visual inspection within hundreds of microscopic fields-of-view per investigated brain or brain region. Reliance on visual inspection forces stereologic cell counting to be very labor-intensive and time-consuming, and is the main reason why biased, non-stereologic two-dimensional (2D cell counting approaches have remained in widespread use. We present an evaluation of the performance of modern automated cell detection and segmentation algorithms as a potential alternative to the manual approach in stereologic cell counting. The image data used in this study were 3D microscopic images of thick brain tissue sections prepared with a variety of commonly used nuclear and cytoplasmic stains. The evaluation compared the numbers and locations of cells identified unambiguously and counted exhaustively by an expert observer with those found by three automated 3D cell detection algorithms: nuclei segmentation from the FARSIGHT toolkit, nuclei segmentation by 3D multiple level set methods, and the 3D object counter plug-in for ImageJ. Of these methods, FARSIGHT performed best, with true-positive detection rates between 38–99% and false-positive rates from 3.6–82%. The results demonstrate that the current automated methods suffer from lower detection rates and higher false-positive rates than are acceptable for obtaining valid estimates of cell numbers. Thus, at present, stereologic cell counting with manual decision for object inclusion according to unbiased stereologic counting rules remains the only adequate method for unbiased cell quantification in histologic tissue sections.

Comment on: 'A Poisson resampling method for simulating reduced counts in nuclear medicine images'.

Science.gov (United States)

de Nijs, Robin

2015-07-21

In order to be able to calculate half-count images from already acquired data, White and Lawson published their method based on Poisson resampling. They verified their method experimentally by measurements with a Co-57 flood source. In this comment their results are reproduced and confirmed by a direct numerical simulation in Matlab. Not only Poisson resampling, but also two direct redrawing methods were investigated. Redrawing methods were based on a Poisson and a Gaussian distribution. Mean, standard deviation, skewness and excess kurtosis half-count/full-count ratios were determined for all methods, and compared to the theoretical values for a Poisson distribution. Statistical parameters showed the same behavior as in the original note and showed the superiority of the Poisson resampling method. Rounding off before saving of the half count image had a severe impact on counting statistics for counts below 100. Only Poisson resampling was not affected by this, while Gaussian redrawing was less affected by it than Poisson redrawing. Poisson resampling is the method of choice, when simulating half-count (or less) images from full-count images. It simulates correctly the statistical properties, also in the case of rounding off of the images.

Mitosis counting in breast cancer : object-level interobserver agreement and comparison to an automatic method

NARCIS (Netherlands)

Veta, M.; van Diest, P.J.; Jiwa, M.; Al-Janabi, S.; Pluim, J.P.W.

2016-01-01

BACKGROUND: Tumor proliferation speed, most commonly assessed by counting of mitotic figures in histological slide preparations, is an important biomarker for breast cancer. Although mitosis counting is routinely performed by pathologists, it is a tedious and subjective task with poor

Mitosis Counting in Breast Cancer : Object-Level Interobserver Agreement and Comparison to an Automatic Method

NARCIS (Netherlands)

Veta, Mitko; van Diest, Paul J; Jiwa, Mehdi; Al-Janabi, Shaimaa; Pluim, JPW

2016-01-01

BACKGROUND: Tumor proliferation speed, most commonly assessed by counting of mitotic figures in histological slide preparations, is an important biomarker for breast cancer. Although mitosis counting is routinely performed by pathologists, it is a tedious and subjective task with poor

High Triglycerides Are Associated with Low Thrombocyte Counts and High VEGF in Nephropathia Epidemica.

Science.gov (United States)

Martynova, Ekaterina V; Valiullina, Aygul H; Gusev, Oleg A; Davidyuk, Yuriy N; Garanina, Ekaterina E; Shakirova, Venera G; Khaertynova, Ilsiyar; Anokhin, Vladimir A; Rizvanov, Albert A; Khaiboullina, Svetlana F

2016-01-01

Nephropathia epidemica (NE) is a mild form of hemorrhagic fever with renal syndrome. Several reports have demonstrated a severe alteration in lipoprotein metabolism. However, little is known about changes in circulating lipids in NE. The objectives of this study were to evaluate changes in serum total cholesterol, high density cholesterol (HDCL), and triglycerides. In addition to evaluation of serum cytokine activation associations, changes in lipid profile and cytokine activation were determined for gender, thrombocyte counts, and VEGF. Elevated levels of triglycerides and decreased HDCL were observed in NE, while total cholesterol did not differ from controls. High triglycerides were associated with both the lowest thrombocyte counts and high serum VEGF, as well as a high severity score. Additionally, there were higher levels of triglycerides in male than female NE patients. Low triglycerides were associated with upregulation of IFN- γ and IL-12, suggesting activation of Th1 helper cells. Furthermore, levels of IFN- γ and IL-12 were increased in patients with lower severity scores, suggesting that a Th1 type immune response is playing protective role in NE. These combined data advance the understanding of NE pathogenesis and indicate a role for high triglycerides in disease severity.

Variants of the Borda count method for combining ranked classifier hypotheses

NARCIS (Netherlands)

van Erp, Merijn; Schomaker, Lambert; Schomaker, Lambert; Vuurpijl, Louis

2000-01-01

The Borda count is a simple yet effective method of combining rankings. In pattern recognition, classifiers are often able to return a ranked set of results. Several experiments have been conducted to test the ability of the Borda count and two variant methods to combine these ranked classifier

Evaluation of very low-level waste disposal based on fuzzed method

International Nuclear Information System (INIS)

Wang Yongli; Ni Shijun; Duo Tianhui; Huang Zhigang

2012-01-01

This paper studies the geology conditions at a very low-level waste disposal site in southwest China, including geology, hydrogeology, and geologic hazards. On the basis of investigation this waste disposal site is evaluated using fuzzed method. Evaluation results prove that site A is better than site B. (authors)

Detector Motion Method to Increase Spatial Resolution in Photon-Counting Detectors

Energy Technology Data Exchange (ETDEWEB)

Lee, Daehee; Park, Kyeongjin; Lim, Kyung Taek; Cho, Gyuseong [Korea Advanced Institute of Science and Technology, Daejon (Korea, Republic of)

2017-03-15

Medical imaging requires high spatial resolution of an image to identify fine lesions. Photoncounting detectors in medical imaging have recently been rapidly replacing energy-integrating detectors due to the former's high spatial resolution, high efficiency and low noise. Spatial resolution in a photon counting image is determined by the pixel size. Therefore, the smaller the pixel size, the higher the spatial resolution that can be obtained in an image. However, detector redesigning is required to reduce pixel size, and an expensive fine process is required to integrate a signal processing unit with reduced pixel size. Furthermore, as the pixel size decreases, charge sharing severely deteriorates spatial resolution. To increase spatial resolution, we propose a detector motion method using a large pixel detector that is less affected by charge sharing. To verify the proposed method, we utilized a UNO-XRI photon-counting detector (1-mm CdTe, Timepix chip) at the maximum X-ray tube voltage of 80 kVp. A similar spatial resolution of a 55-μm-pixel image was achieved by application of the proposed method to a 110-μm-pixel detector with a higher signal-to-noise ratio. The proposed method could be a way to increase spatial resolution without a pixel redesign when pixels severely suffer from charge sharing as pixel size is reduced.

The Method of Recursive Counting: Can one go further?

International Nuclear Information System (INIS)

Creutz, M.; Horvath, I.

1993-12-01

After a short review of the Method of Recursive Counting we introduce a general algebraic description of recursive lattice building. This provides a rigorous framework for discussion of method's limitations

Low-level detection and quantification of Plutonium(III, IV, V,and VI) using a liquid core waveguide

International Nuclear Information System (INIS)

Wilson, Richard E.; Hu, Yung-Jin; Nitsche, Heino

2003-01-01

Understanding the aqueous chemistry of plutonium, in particular in environmental conditions, is often complicated by plutonium's complex redox chemistry. Because plutonium possesses four oxidation states, all of which can coexist in solution, a reliable method for the identification of these oxidation states is needed. The identification of plutonium oxidation states at low levels in aqueous solution is often accomplished through an indirect determination using series of liquid-liquid extraction procedures using oxidation state specific reagents such as HDEHP and TTA. While these methods, coupled with radioactive counting techniques provide superior limits of detection they may influence the plutonium redox equilibrium, are time consuming, waste intensive and costly. Other analytical methods such as mass spectrometry and radioactive counting as stand alone methods provide excellent detection limits but lack the ability to discriminate between the oxidation states of the plutonium ions in solution

Detection limits for radioanalytical counting techniques

International Nuclear Information System (INIS)

Hartwell, J.K.

1975-06-01

In low-level radioanalysis it is usually necessary to test the sample net counts against some ''Critical Level'' in order to determine if a given result indicates detection. This is an interpretive review of the work by Nicholson (1963), Currie (1968) and Gilbert (1974). Nicholson's evaluation of three different computational formulas for estimation of the ''Critical Level'' is discussed. The details of Nicholson's evaluation are presented along with a basic discussion of the testing procedures used. Recommendations are presented for calculation of confidence intervals, for reporting of analytical results, and for extension of the derived formula to more complex cases such as multiple background counts, multiple use of a single background count, and gamma spectrometric analysis

The intensity detection of single-photon detectors based on photon counting probability density statistics

International Nuclear Information System (INIS)

Zhang Zijing; Song Jie; Zhao Yuan; Wu Long

2017-01-01

Single-photon detectors possess the ultra-high sensitivity, but they cannot directly respond to signal intensity. Conventional methods adopt sampling gates with fixed width and count the triggered number of sampling gates, which is capable of obtaining photon counting probability to estimate the echo signal intensity. In this paper, we not only count the number of triggered sampling gates, but also record the triggered time position of photon counting pulses. The photon counting probability density distribution is obtained through the statistics of a series of the triggered time positions. Then Minimum Variance Unbiased Estimation (MVUE) method is used to estimate the echo signal intensity. Compared with conventional methods, this method can improve the estimation accuracy of echo signal intensity due to the acquisition of more detected information. Finally, a proof-of-principle laboratory system is established. The estimation accuracy of echo signal intensity is discussed and a high accuracy intensity image is acquired under low-light level environments. (paper)

Optimization of simultaneous tritium–radiocarbon internal gas proportional counting

Energy Technology Data Exchange (ETDEWEB)

Bonicalzi, R. M.; Aalseth, C. E.; Day, A. R.; Hoppe, E. W.; Mace, E. K.; Moran, J. J.; Overman, C. T.; Panisko, M. E.; Seifert, A.

2016-03-01

Specific environmental applications can benefit from dual tritium and radiocarbon measurements in a single compound. Assuming typical environmental levels, it is often the low tritium activity relative to the higher radiocarbon activity that limits the dual measurement. In this paper, we explore the parameter space for a combined tritium and radiocarbon measurement using a methane sample mixed with an argon fill gas in low-background proportional counters of a specific design. We present an optimized methane percentage, detector fill pressure, and analysis energy windows to maximize measurement sensitivity while minimizing count time. The final optimized method uses a 9-atm fill of P35 (35% methane, 65% argon), and a tritium analysis window from 1.5 to 10.3 keV, which stops short of the tritium beta decay endpoint energy of 18.6 keV. This method optimizes tritium counting efficiency while minimizing radiocarbon beta decay interference.

Primary brain tumors treated with steroids and radiotherapy: Low CD4 counts and risk of infection

International Nuclear Information System (INIS)

Hughes, Michael A.; Parisi, Michele; Grossman, Stuart; Kleinberg, Lawrence

2005-01-01

Purpose: Patients with primary brain tumors are often treated with high doses of corticosteroids for prolonged periods to reduce intracranial swelling and alleviate symptoms such as headaches. This treatment may lead to immunosuppression, placing the patient at risk of life-threatening opportunistic infections, such as Pneumocystis carinii pneumonia. The risk of contracting some types of infection may be reduced with prophylactic antibiotics. The purpose of this study was to determine the occurrence of low CD4 counts and whether monitoring CD4 counts during and after radiotherapy (RT) is warranted. Methods and Materials: CD4 counts were measured during RT in 70 of 76 consecutive patients with newly diagnosed Grade III and IV astrocytoma and anaplastic oligodendroglioma treated with corticosteroids and seen at the Johns Hopkins Hospital. Weekly CD4 measurements were taken in the most recent 25 patients. Prophylactic trimethoprim-sulfamethoxazole (160 mg/800 mg p.o. every Monday, Wednesday, and Friday) or dapsone (100 mg p.o. daily) in those with sulfa allergy was prescribed only if patients developed a low CD4 count. Carmustine chemotherapy wafers were placed at surgery in 23% of patients, evenly distributed between the groups. No patient received any other chemotherapy concurrent with RT. Results: CD4 counts decreased to 3 in 17 (24%) of 70 patients. For the 25 patients with weekly CD4 counts, all CD4 counts were >450/mm 3 before RT, but 6 (24%) of 25 fell to 3 during RT. Patients with counts 3 were significantly more likely to be hospitalized (41% vs. 9%, p <0.01) and be hospitalized for infection (23% vs. 4%, p <0.05) during RT. Overall survival was not significantly different between the groups. All patients with low CD4 counts were treated with prophylactic antibiotics, and no patient developed Pneumocystis carinii pneumonia. No patients developed a serious adverse reaction to antibiotic therapy. The mean dose of steroids, mean minimal white blood cell count

EARLY IDENTIFICATION OF SWINE INFLUENZA A (H1N1- BASING ONEPIDEMIOLOGIC CLUE, CLINICAL PRESENTATION, IMAGING FINDINGS, PERIPHERAL LEUCOCYTE COUNTS AND SPO2 LEVELS

Directory of Open Access Journals (Sweden)

Venkateswararao Kopparti

2017-11-01

Full Text Available BACKGROUND The present study is a retrospective study of 22 cases of RT-PCR positive swine influenza spanning from 2014 to 20-09-2017 with main objective of early identification of influenza A H1N1 basing on epidemiological clue, clinical presentation, imaging findings and lab parameters as early antiviral therapy and judicious management of ARDS brings good outcome as per available literature. 1,2,3 MATERIAL AND METHODS 22 confirmed adult cases of swine influenza by throat/nasopharyngeal swab RT-PCR for H1N1 were studied in terms of clinical presentation, imaging findings, lab manifestations and SpO2 levels4 with particular emphasis on imaging findings. RESULTS 95% presented with symptoms of Influenza-Like Illness (ILI. Nearly, 80% of patients belonged to fourth to fifth decades. Leucocyte count was normal in 75% and 25% had low leucocyte count (<4000, SpO2 levels were normal in 25% and low in 75% cases. CXR was abnormal in 82% of cases of which 83% had mid/lower zone peripheral, patchy, pleural-based consolidations and 17% showed all lung zone opacities. HRCT chest done in 32% of cases showed similar features of chest xray findings with dominant mid/lower zone pleural-based consolidations to ground-glass haziness without pleural effusions and no mediastinal nodal involvement. CONCLUSION As intermittent outbreaks of swine influenza are still continuing in India with recent spurt in incidence in the months of April/May 2017, early diagnosis of H1N1 A is necessary for improved outcome. Early diagnosis is feasible by ILI presentation, normal or low leucocyte count, low SpO2 levels and characteristic radiologic findings of bilateral mid/lower zone pleural-based peripheral patchy opacities to consolidations. As this can be done at peripheral level, primary care physicians need to be sensitised in early diagnosis and treatment and prompt referral to higher centres when needed. Since, the present study is a retrospective one and of public health

The effect of volume and quenching on estimation of counting efficiencies in liquid scintillation counting

International Nuclear Information System (INIS)

Knoche, H.W.; Parkhurst, A.M.; Tam, S.W.

1979-01-01

The effect of volume on the liquid scintillation counting performance of 14 C-samples has been investigated. A decrease in counting efficiency was observed for samples with volumes below about 6 ml and those above about 18 ml when unquenched samples were assayed. Two quench-correction methods, sample channels ratio and external standard channels ratio, and three different liquid scintillation counters, were used in an investigation to determine the magnitude of the error in predicting counting efficiencies when small volume samples (2 ml) with different levels of quenching were assayed. The 2 ml samples exhibited slightly greater standard deviations of the difference between predicted and determined counting efficiencies than did 15 ml samples. Nevertheless, the magnitude of the errors indicate that if the sample channels ratio method of quench correction is employed, 2 ml samples may be counted in conventional counting vials with little loss in counting precision. (author)

The Box-and-Dot Method: A Simple Strategy for Counting Significant Figures

Science.gov (United States)

Stephenson, W. Kirk

2009-01-01

A visual method for counting significant digits is presented. This easy-to-learn (and easy-to-teach) method, designated the box-and-dot method, uses the device of "boxing" significant figures based on two simple rules, then counting the number of digits in the boxes. (Contains 4 notes.)

Subjective annoyance caused by indoor low-level and low frequency noise and control method

Institute of Scientific and Technical Information of China (English)

DI Guo-qing; ZHANG Bang-jun; SHANG Qi

2005-01-01

The influence of low-level noise has not been widely noticed. This paper discovered that low-level and low frequency noise(Aweighted equivalent level Leq ＜ 45 dB) causes higher probability of subjective annoyance. The fuzzy mathematic principle was applied to deal with the threshold level of subjective annoyance from noise in this study; there is preferable relationship between the indoor noise and noise annoyance at low frequency noise level. Study indicated at the same centered noise level, the change of annoyance probability is mainly caused by the change of the frequency spectrum characteristic of the indoor noise. Under low noise level environment, without change of the medium-low frequency noise, the slight increase of medium-high frequency noise level with the help of noise sheltering effect can significantly reduce the noise annoyance. This discovery brings a new resolution on how to improve the environmental quality of working or living places. A noise control model is given in this study according to the acoustic analysis.

Optimization of simultaneous tritium–radiocarbon internal gas proportional counting

Energy Technology Data Exchange (ETDEWEB)

Bonicalzi, R.M. [Seattle Central College, 1701 Broadway, Seattle, WA 98122 (United States); Aalseth, C.E.; Day, A.R.; Hoppe, E.W. [Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, WA 99352 (United States); Mace, E.K., E-mail: Emily.Mace@pnl.gov [Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, WA 99352 (United States); Moran, J.J.; Overman, C.T.; Panisko, M.E.; Seifert, A. [Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, WA 99352 (United States)

2016-03-21

Specific environmental applications can benefit from dual tritium and radiocarbon measurements in a single compound. Assuming typical environmental levels, it is often the low tritium activity relative to the higher radiocarbon activity that limits the dual measurement. In this paper, we explore the parameter space for a combined tritium and radiocarbon measurement using a natural methane sample mixed with an argon fill gas in low-background proportional counters of a specific design. We present an optimized methane percentage, detector fill pressure, and analysis energy windows to maximize measurement sensitivity while minimizing count time. The final optimized method uses a 9-atm fill of P35 (35% methane, 65% argon), and a tritium analysis window from 1.5 to 10.3 keV, which stops short of the tritium beta decay endpoint energy of 18.6 keV. This method optimizes tritium-counting efficiency while minimizing radiocarbon beta-decay interference. - Highlights: • Use of a single compound (methane) for dual tritium and radiocarbon measurements. • Optimized analysis window for simultaneous tritium and radiocarbon measurement. • Allows for optimization of tritium counting in the presence of radiocarbon.

Clinical significance of changes of serum NSE, cortisol, ADM, calcium, magnesium levels and platalet count in neonates with hypoxic-ischemic encephalopathy (HIE)

International Nuclear Information System (INIS)

Lv Weihua; Huang Weiliang

2009-01-01

Objective: To study the clinical significance of changes of serum NSE, cortisol, ADM, Ca ++ , Mg ++ levels and platalet count in neonates with HIE. Methods: Serum NSE, ADM(with RIA), cortisol(with CLIA), Ca ++ and Mg ++ (with biochemistry) levels and platalet count were determined in 52 neonates with HIE(mild, n=26, moderate, n=16, advanced, n=10) and 30 controls. Results: In the neonates with mild HIE, the serum NSE and ADM levels were not significantly different from those in controls (P>0.05) but cortisol levels were significantly higher (P ++ and Mg ++ levels as well as decrease of platelet count, might reflect the severity of the disease process of HIE in neonates and might be of prognostic importance. (authors)

Methods of counting ribs on chest CT: the modified sternomanubrial approach

Energy Technology Data Exchange (ETDEWEB)

Yi, Kyung Sik; Kim, Sung Jin; Jeon, Min Hee; Lee, Seung Young; Bae, Il Hun [Chungbuk National University, Cheongju (Korea, Republic of)

2007-08-15

The purpose of this study was to evaluate the accuracy of each method of counting ribs on chest CT and to propose a new method: the anterior approach with using the sternocostal joints. CT scans of 38 rib lesions of 27 patients were analyzed (fracture: 25, metastasis: 11, benign bone disease: 2). Each lesion was independently counted by three radiologists with using three different methods for counting ribs: the sternoclavicular approach, the xiphisternal approach and the modified sternomanubrial approach. The rib lesions were divided into three parts of evaluation of each method according to the location of the lesion as follows: the upper part (between the first and fourth thoracic vertebra), the middle part (between the fifth and eighth) and the lower part (between the ninth and twelfth). The most accurate method was a modified sternomanubrial approach (99.1%). The accuracies of a xiphisternal approach and a sternoclavicular approach were 95.6% and 88.6%, respectively. A modified sternomanubrial approach showed the highest accuracies in all three parts (100%, 100% and 97.9%, respectively). We propose a new method for counting ribs, the modified sternomanubrial approach, which was more accurate than the known methods in any parts of the bony thorax, and it may be an easier and quicker method than the others in clinical practice.

A New Method for Calculating Counts in Cells

Science.gov (United States)

Szapudi, István

1998-04-01

In the near future, a new generation of CCD-based galaxy surveys will enable high-precision determination of the N-point correlation functions. The resulting information will help to resolve the ambiguities associated with two-point correlation functions, thus constraining theories of structure formation, biasing, and Gaussianity of initial conditions independently of the value of Ω. As one of the most successful methods of extracting the amplitude of higher order correlations is based on measuring the distribution of counts in cells, this work presents an advanced way of measuring it with unprecedented accuracy. Szapudi & Colombi identified the main sources of theoretical errors in extracting counts in cells from galaxy catalogs. One of these sources, termed as measurement error, stems from the fact that conventional methods use a finite number of sampling cells to estimate counts in cells. This effect can be circumvented by using an infinite number of cells. This paper presents an algorithm, which in practice achieves this goal; that is, it is equivalent to throwing an infinite number of sampling cells in finite time. The errors associated with sampling cells are completely eliminated by this procedure, which will be essential for the accurate analysis of future surveys.

Fatigue, serum cytokine levels, and blood cell counts during radiotherapy of patients with breast cancer

International Nuclear Information System (INIS)

Geinitz, Hans; Zimmermann, Frank B.; Stoll, Peter; Thamm, Reinhard; Kaffenberger, Walter; Ansorg, Kai; Keller, Monika; Busch, Raymonde; Beuningen, Dirk van; Molls, Michael

2001-01-01

Purpose: To assess the level of fatigue during the course of adjuvant radiotherapy (RT) of breast cancer patients and its relation to anxiety, depression, serum cytokines, and blood count levels. Methods and Materials: Forty-one patients who received adjuvant RT after breast-conserving surgery were prospectively studied. All patients underwent RT without concomitant chemotherapy. Patients rated their fatigue with two standardized self-assessment instruments, the Fatigue Assessment Questionnaire and a visual analog scale on fatigue intensity, before RT, during weeks 1-5 of RT, and 2 months after RT completion. In addition, the anxiety and depression levels were assessed with the Hospital Anxiety and Depression Scale. A differential blood cell count and the serum levels of the cytokines interleukin (IL)-1β, IL-6, and tumor necrosis factor-α were determined in parallel to the fatigue assessments. Results: Fatigue intensity as assessed with the visual analog scale increased (p<0.001) until treatment week 4 and remained elevated until week 5. Two months after RT, the values had fallen to the pretreatment levels. Fatigue measured with the Fatigue Assessment Questionnaire did not increase significantly during treatment, but the subscores on physical (p=0.035) and cognitive (p=0.015) fatigue were elevated during treatment weeks 4 and 5. Affective fatigue did not change significantly. Anxiety, as rated with the Hospital Anxiety and Depression Scale, declined during RT (p=0.002), but the Hospital Anxiety and Depression Scale depression score did not change significantly. IL-1β, IL-6, and tumor necrosis factor-α levels did not change during therapy and did not correlate with fatigue. Peripheral blood cell levels declined significantly during therapy and were still low 2 months after treatment. Until treatment week 5, lymphocytes were reduced to almost 50% of their initial values. Hemoglobin levels did not correlate with fatigue. Conclusions: We observed an increase in

A practical intercomparison of non-radiometric methods for the determination of low levels of radionuclides

International Nuclear Information System (INIS)

McMahon, A.W.

1991-01-01

Non-Radiometric, methods of elemental analysis have been assessed as alternatives to radiometric methods for the determination of low levels of radionuclides. The methods have been assessed in a practical intercomparison, using a set of samples containing known, low levels of analytes in a variety of matrices. It was found that all of the methods considered have a role to play and are to some extent complementary in terms of cost, rate of sample throughput, elemental coverage, imaging capability sensitivity and quantitative capabilities. Techniques based on mass spectrometry have most to offer in this application, allowing sensitive isotope specific determinations. (author)

Controlling low-level radioactive waste

International Nuclear Information System (INIS)

1990-01-01

This series of information sheets describes at a popular level the sources of low-level radioactive wastes, their associated hazards, methods of storage, transportation and disposal, and the Canadian regulations that cover low-level wastes

Alternative methods for disposal of low-level radioactive wastes. Task 2c: technical requirements for earth mounded concrete bunker disposal of low-level radioactive waste. Volume 4

International Nuclear Information System (INIS)

Miller, W.O.; Bennett, R.D.

1985-10-01

The study reported herein contains the results of Task 2c (Technical Requirements for Earth Mounded Concrete Bunker Disposal of Low-Level Radioactive Waste) of a four-task study entitled ''Criteria for Evaluating Engineered Facilities''. The overall objective of this study is to ensure that the criteria needed to evaluate five alternative low-level radioactive waste (LLW) disposal methods are available to potential license applicants. The earth mounded concrete bunker disposal alternative is one of several methods that may be proposed for disposal of low-level radioactive waste. The name of this alternative is descriptive of the disposal method used in France at the Centre de la Manche. Experience gained with this method at the Centre is described, including unit operations and features and components. Some improvements to the French system are recommended herein, including the use of previous backfill around monoliths and extending the limits of a low permeability surface layer. The applicability of existing criteria developed for near-surface disposal (10 CFR Part 61 Subpart D) to the earth mounded concrete bunker disposal method, as assessed in Task 1, are reassessed herein. With minor qualifications, these criteria were found to be applicable in the reassessment. These conclusions differ slightly from the Task 1 findings

A comparison of Ki-67 counting methods in luminal Breast Cancer: The Average Method vs. the Hot Spot Method.

Science.gov (United States)

Jang, Min Hye; Kim, Hyun Jung; Chung, Yul Ri; Lee, Yangkyu; Park, So Yeon

2017-01-01

In spite of the usefulness of the Ki-67 labeling index (LI) as a prognostic and predictive marker in breast cancer, its clinical application remains limited due to variability in its measurement and the absence of a standard method of interpretation. This study was designed to compare the two methods of assessing Ki-67 LI: the average method vs. the hot spot method and thus to determine which method is more appropriate in predicting prognosis of luminal/HER2-negative breast cancers. Ki-67 LIs were calculated by direct counting of three representative areas of 493 luminal/HER2-negative breast cancers using the two methods. We calculated the differences in the Ki-67 LIs (ΔKi-67) between the two methods and the ratio of the Ki-67 LIs (H/A ratio) of the two methods. In addition, we compared the performance of the Ki-67 LIs obtained by the two methods as prognostic markers. ΔKi-67 ranged from 0.01% to 33.3% and the H/A ratio ranged from 1.0 to 2.6. Based on the receiver operating characteristic curve method, the predictive powers of the KI-67 LI measured by the two methods were similar (Area under curve: hot spot method, 0.711; average method, 0.700). In multivariate analysis, high Ki-67 LI based on either method was an independent poor prognostic factor, along with high T stage and node metastasis. However, in repeated counts, the hot spot method did not consistently classify tumors into high vs. low Ki-67 LI groups. In conclusion, both the average and hot spot method of evaluating Ki-67 LI have good predictive performances for tumor recurrence in luminal/HER2-negative breast cancers. However, we recommend using the average method for the present because of its greater reproducibility.

A comparison of Ki-67 counting methods in luminal Breast Cancer: The Average Method vs. the Hot Spot Method.

Directory of Open Access Journals (Sweden)

Min Hye Jang

Full Text Available In spite of the usefulness of the Ki-67 labeling index (LI as a prognostic and predictive marker in breast cancer, its clinical application remains limited due to variability in its measurement and the absence of a standard method of interpretation. This study was designed to compare the two methods of assessing Ki-67 LI: the average method vs. the hot spot method and thus to determine which method is more appropriate in predicting prognosis of luminal/HER2-negative breast cancers. Ki-67 LIs were calculated by direct counting of three representative areas of 493 luminal/HER2-negative breast cancers using the two methods. We calculated the differences in the Ki-67 LIs (ΔKi-67 between the two methods and the ratio of the Ki-67 LIs (H/A ratio of the two methods. In addition, we compared the performance of the Ki-67 LIs obtained by the two methods as prognostic markers. ΔKi-67 ranged from 0.01% to 33.3% and the H/A ratio ranged from 1.0 to 2.6. Based on the receiver operating characteristic curve method, the predictive powers of the KI-67 LI measured by the two methods were similar (Area under curve: hot spot method, 0.711; average method, 0.700. In multivariate analysis, high Ki-67 LI based on either method was an independent poor prognostic factor, along with high T stage and node metastasis. However, in repeated counts, the hot spot method did not consistently classify tumors into high vs. low Ki-67 LI groups. In conclusion, both the average and hot spot method of evaluating Ki-67 LI have good predictive performances for tumor recurrence in luminal/HER2-negative breast cancers. However, we recommend using the average method for the present because of its greater reproducibility.

Low-dose electron energy-loss spectroscopy using electron counting direct detectors.

Science.gov (United States)

Maigné, Alan; Wolf, Matthias

2018-03-01

Since the development of parallel electron energy loss spectroscopy (EELS), charge-coupled devices (CCDs) have been the default detectors for EELS. With the recent development of electron-counting direct-detection cameras, micrographs can be acquired under very low electron doses at significantly improved signal-to-noise ratio. In spectroscopy, in particular in combination with a monochromator, the signal can be extremely weak and the detection limit is principally defined by noise introduced by the detector. Here we report the use of an electron-counting direct-detection camera for EEL spectroscopy. We studied the oxygen K edge of amorphous ice and obtained a signal noise ratio up to 10 times higher than with a conventional CCD.We report the application of electron counting to record time-resolved EEL spectra of a biological protein embedded in amorphous ice, revealing chemical changes observed in situ while exposed by the electron beam. A change in the fine structure of nitrogen K and the carbon K edges were recorded during irradiation. A concentration of 3 at% nitrogen was detected with a total electron dose of only 1.7 e-/Å2, extending the boundaries of EELS signal detection at low electron doses.

A rapid method for counting nucleated erythrocytes on stained blood smears by digital image analysis

Science.gov (United States)

Gering, E.; Atkinson, C.T.

2004-01-01

Measures of parasitemia by intraerythrocytic hematozoan parasites are normally expressed as the number of infected erythrocytes per n erythrocytes and are notoriously tedious and time consuming to measure. We describe a protocol for generating rapid counts of nucleated erythrocytes from digital micrographs of thin blood smears that can be used to estimate intensity of hematozoan infections in nonmammalian vertebrate hosts. This method takes advantage of the bold contrast and relatively uniform size and morphology of erythrocyte nuclei on Giemsa-stained blood smears and uses ImageJ, a java-based image analysis program developed at the U.S. National Institutes of Health and available on the internet, to recognize and count these nuclei. This technique makes feasible rapid and accurate counts of total erythrocytes in large numbers of microscope fields, which can be used in the calculation of peripheral parasitemias in low-intensity infections.

Comment on: 'A Poisson resampling method for simulating reduced counts in nuclear medicine images'

DEFF Research Database (Denmark)

de Nijs, Robin

2015-01-01

In order to be able to calculate half-count images from already acquired data, White and Lawson published their method based on Poisson resampling. They verified their method experimentally by measurements with a Co-57 flood source. In this comment their results are reproduced and confirmed...... by a direct numerical simulation in Matlab. Not only Poisson resampling, but also two direct redrawing methods were investigated. Redrawing methods were based on a Poisson and a Gaussian distribution. Mean, standard deviation, skewness and excess kurtosis half-count/full-count ratios were determined for all...... methods, and compared to the theoretical values for a Poisson distribution. Statistical parameters showed the same behavior as in the original note and showed the superiority of the Poisson resampling method. Rounding off before saving of the half count image had a severe impact on counting statistics...

The Eosinophil Count Tends to Be Negatively Associated with Levels of Serum Glucose in Patients with Adrenal Cushing Syndrome

Directory of Open Access Journals (Sweden)

Younghak Lee

2017-09-01

Full Text Available BackgroundCushing syndrome is characterized by glucose intolerance, cardiovascular disease, and an enhanced systemic inflammatory response caused by chronic exposure to excess cortisol. Eosinopenia is frequently observed in patients with adrenal Cushing syndrome, but the relationship between the eosinophil count in peripheral blood and indicators of glucose level in patients with adrenal Cushing syndrome has not been determined.MethodsA retrospective study was undertaken of the clinical and laboratory findings of 40 patients diagnosed with adrenal Cushing syndrome at Chungnam National University Hospital from January 2006 to December 2016. Clinical characteristics, complete blood cell counts with white blood cell differential, measures of their endocrine function, description of imaging studies, and pathologic findings were obtained from their medical records.ResultsEosinophil composition and count were restored by surgical treatment of all of the patients with adrenal Cushing disease. The eosinophil count was inversely correlated with serum and urine cortisol, glycated hemoglobin, and inflammatory markers in the patients with adrenal Cushing syndrome.ConclusionSmaller eosinophil populations in patients with adrenal Cushing syndrome tend to be correlated with higher levels of blood sugar and glycated hemoglobin. This study suggests that peripheral blood eosinophil composition or count may be associated with serum glucose levels in patients with adrenal Cushing syndrome.

Petrifilm rapid S. aureus Count Plate method for rapid enumeration of Staphylococcus aureus in selected foods: collaborative study.

Science.gov (United States)

Silbernagel, K M; Lindberg, K G

2001-01-01

A rehydratable dry-film plating method for Staphylococcus aureus in foods, the 3M Petrifilm Rapid S. aureus Count Plate method, was compared with AOAC Official Method 975.55 (Staphylococcus aureus in Foods). Nine foods-instant nonfat dried milk, dry seasoned vegetable coating, frozen hash browns, frozen cooked chicken patty, frozen ground raw pork, shredded cheddar cheese, fresh green beans, pasta filled with beef and cheese, and egg custard-were analyzed for S. aureus by 13 collaborating laboratories. For each food tested, the collaborators received 8 blind test samples consisting of a control sample and 3 levels of inoculated test sample, each in duplicate. The mean log counts for the methods were comparable for pasta filled with beef and cheese; frozen hash browns; cooked chicken patty; egg custard; frozen ground raw pork; and instant nonfat dried milk. The repeatability and reproducibility variances of the Petrifilm Rapid S. aureus Count Plate method were similar to those of the standard method.

Packaged low-level waste verification system

Energy Technology Data Exchange (ETDEWEB)

Tuite, K.; Winberg, M.R.; McIsaac, C.V. [Idaho National Engineering Lab., Idaho Falls, ID (United States)

1995-12-31

The Department of Energy through the National Low-Level Waste Management Program and WMG Inc. have entered into a joint development effort to design, build, and demonstrate the Packaged Low-Level Waste Verification System. Currently, states and low-level radioactive waste disposal site operators have no method to independently verify the radionuclide content of packaged low-level waste that arrives at disposal sites for disposition. At this time, the disposal site relies on the low-level waste generator shipping manifests and accompanying records to ensure that low-level waste received meets the site`s waste acceptance criteria. The subject invention provides the equipment, software, and methods to enable the independent verification of low-level waste shipping records to ensure that the site`s waste acceptance criteria are being met. The objective of the prototype system is to demonstrate a mobile system capable of independently verifying the content of packaged low-level waste.

Method Verification Requirements for an Advanced Imaging System for Microbial Plate Count Enumeration.

Science.gov (United States)

Jones, David; Cundell, Tony

2018-01-01

The Growth Direct™ System that automates the incubation and reading of membrane filtration microbial counts on soybean-casein digest, Sabouraud dextrose, and R2A agar differs only from the traditional method in that micro-colonies on the membrane are counted using an advanced imaging system up to 50% earlier in the incubation. Based on the recommendations in USP Validation of New Microbiological Testing Methods , the system may be implemented in a microbiology laboratory after simple method verification and not a full method validation. LAY ABSTRACT: The Growth Direct™ System that automates the incubation and reading of microbial counts on membranes on solid agar differs only from the traditional method in that micro-colonies on the membrane are counted using an advanced imaging system up to 50% earlier in the incubation time. Based on the recommendations in USP Validation of New Microbiological Testing Methods , the system may be implemented in a microbiology laboratory after simple method verification and not a full method validation. © PDA, Inc. 2018.

Low-level effects

International Nuclear Information System (INIS)

Devine, R.T.; Chaput, R.L.

1987-01-01

Risk assignments can be made to given practices involving exposure to radiation, because sufficient data are available for the effects of high-dose, low-LET radiation and because sufficient exists in the methods of extrapolation to low doses and low dose rates. The confidence in the extrapolations is based on the fact that the risk is not expected to be overestimated, using the assumptions made (as opposed to the possibility that the extrapolations represent an accurate estimate of the risk). These risk estimates have been applied to the selection of permissible exposure levels, to show that various amounts of radiation involve no greater risk to the worker than the risk expected in another industry that is generally considered safe. The setting of standards for protection from exposure to low levels of ionizing radiation is made by expert committees at the national and international levels who weigh social factors as well as scientific factors. Data on low-level effects may be applied when assigning a ''probability of causation'' to a certain exposure of radiation. This has become a prominent method for arriving at an equitable award for damages caused by such exposure. The generation of these tables requires as many (if not more) social and political considerations as does the setting up of protection criteria. It is impossible to extract a purely scientific conclusion solely from the protection standards and other legal decisions. Sufficient information exists on low-LET radiation that safety standards for exposure can be rationally (if not scientifically) agreed upon

An improved method for {sup 85}Kr analysis by liquid scintillation counting and its application to atmospheric {sup 85}Kr determination

Energy Technology Data Exchange (ETDEWEB)

Momoshima, Noriyuki, E-mail: momoshima.noriyuki.551@m.kyushu-u.ac.j [Radioisotope Center, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581 (Japan); Inoue, Fumio [Graduate School of Science, Kyushu University, 6-10-1Hakozaki, Higashi-ku, Fukuoka 812-8581 (Japan); Sugihara, Shinji [Radioisotope Center, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581 (Japan); Shimada, Jun [Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555 (Japan); Taniguchi, Makoto [Research Institute for Humanity and Nature, 457-4 Motoyama Kamigamo, Kita-ku, Kyoto 603-8047 (Japan)

2010-08-15

Atmospheric {sup 85}Kr concentration at Fukuoka, Japan was determined by an improved {sup 85}Kr analytical method using liquid scintillation counting (LSC). An average value of 1.54 {+-} 0.05 Bq m{sup -3} was observed in 2008, which is about two times that measured in 1981 at Fukuoka, indicating a 29 mBq y{sup -1} rate of increase as an average for these 27 years. The analytical method developed involves collecting Kr from air using activated charcoal at liquid N{sub 2} temperature and purifying it using He at dry ice temperature, followed by Kr separation by gas chromatography. An overall Kr recovery of 76.4 {+-} 8.1% was achieved when Kr was analyzed in 500-1000 l of air. The Kr isolated by gas chromatography was collected on silica gel in a quartz glass vial cooled to liquid N{sub 2} temperature and the activity of {sup 85}Kr was measured with a low-background LS counter. The detection limit of {sup 85}Kr activity by the present analytical method is 0.0015 Bq at a 95% confidence level, including all propagation errors, which is equivalent with {sup 85}Kr in 1.3 l of the present air under the analytical conditions of 72.1% counting efficiency, 0.1597 cps background count rate, and 76.4% Kr recovery.

Instrumental analysis of low level of Cs-137 in marine samples by gamma spectrometry; Analise instrumental de baixos niveis de Cs-137 em amostras marinhas por espectrometria gama

Energy Technology Data Exchange (ETDEWEB)

Figueira, Rubens C.L.; Silva, Luiz R.N.; Figueiredo, Ana M.G.; Cunha, Ieda I.L. [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil). Supervisao de Radioquimica

1997-12-31

An instrumental method for low level Cs-137 analysis in marine samples is presented. The method consists in the detector calibration, as well as, determination of detector counting efficiency, accumulative counting of both background and sample and smoothing of 661.6 keV photopeak. The methodology was applied in reference samples and in sediments samples of south Brazilian coast 11 refs., 6 figs., 4 tabs.; e-mail: figueira at net.ipen.br

Count rate balance method of measuring sediment transport of sand beds by radioactive tracers

International Nuclear Information System (INIS)

Sauzay, G.

1968-01-01

Radioactive tracers are applied to the direct measurement of the sediment transport rate of sand beds. The theoretical measurement formula is derived: the variation of the count rate balance is inverse of that of the transport thickness. Simultaneously the representativeness of the tracer is critically studied. The minimum quantity of tracer which has to be injected in order to obtain a correct statistical definition of count rate given by a low number of grains 'seen' by the detector is then studied. A field experiment was made and has let to study the technological conditions for applying this method: only the treatment of results is new, the experiment itself is carried out with conventional techniques applied with great care. (author) [fr

Validation parameters of instrumental method for determination of total bacterial count in milk

Directory of Open Access Journals (Sweden)

Nataša Mikulec

2004-10-01

Full Text Available The method of flow citometry as rapid, instrumental and routine microbiological method is used for determination of total bacterial count in milk. The results of flow citometry are expressed as individual bacterial cells count. Problems regarding the interpretation of the results of total bacterial count can be avoided by transformation of the results of flow citometry method onto the scale of reference method (HRN ISO 6610:2001.. The method of flow citometry, like any analitycal method, according to the HRN EN ISO/IEC 17025:2000 standard, requires validation and verification. This paper describes parameters of validation: accuracy, precision, specificity, range, robustness and measuring uncertainty for the method of flow citometry.

A color fusion method of infrared and low-light-level images based on visual perception

Science.gov (United States)

Han, Jing; Yan, Minmin; Zhang, Yi; Bai, Lianfa

2014-11-01

The color fusion images can be obtained through the fusion of infrared and low-light-level images, which will contain both the information of the two. The fusion images can help observers to understand the multichannel images comprehensively. However, simple fusion may lose the target information due to inconspicuous targets in long-distance infrared and low-light-level images; and if targets extraction is adopted blindly, the perception of the scene information will be affected seriously. To solve this problem, a new fusion method based on visual perception is proposed in this paper. The extraction of the visual targets ("what" information) and parallel processing mechanism are applied in traditional color fusion methods. The infrared and low-light-level color fusion images are achieved based on efficient typical targets learning. Experimental results show the effectiveness of the proposed method. The fusion images achieved by our algorithm can not only improve the detection rate of targets, but also get rich natural information of the scenes.

Vessel used in radiation counting to determine radioactivity levels

International Nuclear Information System (INIS)

Charlton, J.C.; Glover, J.S.; Shephard, B.P.

1977-01-01

This invention concerns the vessels used in radiation counting to determine radioactivity levels. These vessels prove to be particularly useful in analyses of the kind where a radioactive element or compound is separated into two phases and the radioactivity of one phase is determined. Such a vessel used in the counting of radiation includes an organic plastic substance tube appreciably cylindrical in shape whose upper end is open whilst the lower end is closed and integral with it, and an anti-radiation shield in metal or in metal reinforced plastic located at the lower end of the tube and extending along the wall of the tube up to a given height. The vessel contains a reaction area of 1 to 10 ml for holding fluid reagents [fr

Low-level multicounter {beta}/{gamma} systems with external guards in surface and shallow underground laboratories

Energy Technology Data Exchange (ETDEWEB)

Theodorsson, P [Iceland Univ. (Iceland). Science Inst.

1997-03-01

When weak samples are measured it is important that they can be given ample counting time in order to obtain satisfactory accuracy and that the background count rate can be checked well. This calls for a high counting capacity, which multidetectors can bring us. I will discuss development possibilities of low-level {beta}/{gamma} multidetector systems with an external anticosmic shield that will in many cases be operated in underground laboratories. These simple and low-cost system can frequently help us in increasing the number of detectors. Three concepts are combined in these systems: (1) multidetectors, (2) an external anticosmic (or guard) detector arrangement and (3) overburden shielding. (orig.)

Low-level multicounter β/γ systems with external guards in surface and shallow underground laboratories

International Nuclear Information System (INIS)

Theodorsson, P.

1997-01-01

When weak samples are measured it is important that they can be given ample counting time in order to obtain satisfactory accuracy and that the background count rate can be checked well. This calls for a high counting capacity, which multidetectors can bring us. I will discuss development possibilities of low-level β/γ multidetector systems with an external anticosmic shield that will in many cases be operated in underground laboratories. These simple and low-cost system can frequently help us in increasing the number of detectors. Three concepts are combined in these systems: (1) multidetectors, (2) an external anticosmic (or guard) detector arrangement and (3) overburden shielding. (orig.)

A novel method for detecting and counting overlapping tracks in SSNTD by image processing techniques

International Nuclear Information System (INIS)

Ab Azar, N.; Babakhani, A.; Broumandnia, A.; Sepanloo, K.

2016-01-01

Overlapping object detection and counting is a challenge in image processing. A new method for detecting and counting overlapping circles is presented in this paper. This method is based on pattern recognition and feature extraction using “neighborhood values“ in an object image by implementation of image processing techniques. The junction points are detected by assignment of a value for each pixel in an image. As is shown, the neighborhood values for junction points are larger than the values for other points. This distinction of neighborhood values is the main feature which can be utilized to identify the junction points and to count the overlapping tracks. This method can be used for recognizing and counting charged particle tracks, blood cells and also cancer cells. The method is called “Track Counting based on Neighborhood Values” and is symbolized by “TCNV”. - Highlights: • A new method is introduced to recognize nuclear tracks by image processing. • The method is used to specify neighborhood pixels in junction points in overlapping tracks. • Enhanced method of counting overlapping tracks. • New counting system has linear behavior in counting tracks with density less than 300,000 tracks per cm"2. • In the new method, the overlap tracks can be recognized even to 10× tracks and more.

Pathway analysis for alternate low-level waste disposal methods

International Nuclear Information System (INIS)

Rao, R.R.; Kozak, M.W.; McCord, J.T.; Olague, N.E.

1992-01-01

The purpose of this paper is to evaluate a complete set of environmental pathways for disposal options and conditions that the Nuclear Regulatory Commission (NRC) may analyze for a low-level radioactive waste (LLW) license application. The regulations pertaining In the past, shallow-land burial has been used for the disposal of low-level radioactive waste. However, with the advent of the State Compact system of LLW disposal, many alternative technologies may be used. The alternative LLW disposal facilities include below- ground vault, tumulus, above-ground vault, shaft, and mine disposal This paper will form the foundation of an update of the previously developed Sandia National Laboratories (SNL)/NRC LLW performance assessment methodology. Based on the pathway assessment for alternative disposal methods, a determination will be made about whether the current methodology can satisfactorily analyze the pathways and phenomena likely to be important for the full range of potential disposal options. We have attempted to be conservative in keeping pathways in the lists that may usually be of marginal importance. In this way we can build confidence that we have spanned the range of cases likely to be encountered at a real site. Results of the pathway assessment indicate that disposal methods can be categorized in groupings based on their depth of disposal. For the deep disposal options of shaft and mine disposal, the key pathways are identical. The shallow disposal options, such as tumulus, shallow-land, and below-ground vault disposal also may be grouped together from a pathway analysis perspective. Above-ground vault disposal cannot be grouped with any of the other disposal options. The pathway analysis shows a definite trend concerning depth of disposal. The above-ground option has the largest number of significant pathways. As the waste becomes more isolated, the number of significant pathways is reduced. Similar to shallow-land burial, it was found that for all

Determination of radon in indoor air in Quebec by liquid scintillation counting in ortho-xylene

Energy Technology Data Exchange (ETDEWEB)

Chah, B; Zikovsky, L; Champagne, P [Ecole Polytechnique, Montreal, PQ (Canada)

1992-01-01

A new method for the determination of radon in air has been developed. it is based on low temperature absorption of radon in ortho-xylene followed by liquid scintillation counting. The method is reasonably fast and sensitive enough to analyse air without precipitation. The detection limit at the 95% confidence level for a 20 l air sample and 1 h counting time is 2 mBql{sup -1}. Radon concentrations measured in indoor air in Quebec varied from 7 to 162 mBql{sup -1}. (Author).

Sperm counts and serum follicle-stimulating hormone levels before and after radiotherapy and chemotherapy in men with testicular germ cell cancer

International Nuclear Information System (INIS)

Berthelsen, J.G.

1984-01-01

Sperm counts were low (median, 15 X 10(6) per ejaculate) and serum follicle-stimulating hormone (FSH) levels were moderately elevated (median, 31 IU/l) after unilateral orchiectomy and immediately before radiotherapy and chemotherapy in 34 patients with seminomas and 20 patients with nonseminomatous germ cell tumors. The scattered radiation (0.2 to 1.3 Gray [Gy]) reaching the remaining testicle during radiotherapy caused azoospermia in more than two thirds of the patients. A median of 540 days elapsed after the end of treatment before spermatozoa were again found in semen samples, while a median of 1250 days passed before the pretreatment sperm count was reached. One to 5 years after treatment, sperm counts were still low (median, 6 X 10(6) per ejaculate) and serum FSH was elevated (median, 61 IU/l). The adjuvant chemotherapy given to the 20 patients with nonseminomatous tumors did not appear to affect restitution appreciably

Fluorescent Biosensors Based on Single-Molecule Counting.

Science.gov (United States)

Ma, Fei; Li, Ying; Tang, Bo; Zhang, Chun-Yang

2016-09-20

Biosensors for highly sensitive, selective, and rapid quantification of specific biomolecules make great contributions to biomedical research, especially molecular diagnostics. However, conventional methods for biomolecular assays often suffer from insufficient sensitivity and poor specificity. In some case (e.g., early disease diagnostics), the concentration of target biomolecules is too low to be detected by these routine approaches, and cumbersome procedures are needed to improve the detection sensitivity. Therefore, there is an urgent need for rapid and ultrasensitive analytical tools. In this respect, single-molecule fluorescence approaches may well satisfy the requirement and hold promising potential for the development of ultrasensitive biosensors. Encouragingly, owing to the advances in single-molecule microscopy and spectroscopy over past decades, the detection of single fluorescent molecule comes true, greatly boosting the development of highly sensitive biosensors. By in vitro/in vivo labeling of target biomolecules with proper fluorescent tags, the quantification of certain biomolecule at the single-molecule level is achieved. In comparison with conventional ensemble measurements, single-molecule detection-based analytical methods possess the advantages of ultrahigh sensitivity, good selectivity, rapid analysis time, and low sample consumption. Consequently, single-molecule detection may be potentially employed as an ideal analytical approach to quantify low-abundant biomolecules with rapidity and simplicity. In this Account, we will summarize our efforts for developing a series of ultrasensitive biosensors based on single-molecule counting. Single-molecule counting is a member of single-molecule detection technologies and may be used as a very simple and ultrasensitive method to quantify target molecules by simply counting the individual fluorescent bursts. In the fluorescent sensors, the signals of target biomolecules may be translated to the

A methodology for on line fatigue life monitoring : rainflow cycle counting method

International Nuclear Information System (INIS)

Mukhopadhyay, N.K.; Dutta, B.K.; Kushwaha, H.S.

1992-01-01

Green's function technique is used in on line fatigue life monitoring to convert plant data to stress versus time data. This technique converts plant data most efficiently to stress versus time data. To compute the fatigue usage factor the actual number of cycles experienced by the component is to be found out from stress versus time data. Using material fatigue properties the fatigue usage factor is to be computed from the number of cycles. Generally the stress response is very irregular in nature. To convert an irregular stress history to stress frequency spectra rainflow cycle counting method is used. This method is proved to be superior to other counting methods and yields best fatigue estimates. A code has been developed which computes the number of cycles experienced by the component from stress time history using rainflow cycle counting method. This postprocessor also computes the accumulated fatigue usage factor from material fatigue properties. The present report describes the development of a code to compute fatigue usage factor using rainflow cycle counting technique and presents a real life case study. (author). 10 refs., 10 figs

Counting addressing method: Command addressable element and extinguishing module

Directory of Open Access Journals (Sweden)

Ristić Jovan D.

2009-01-01

Full Text Available The specific requirements that appear in addressable fire detection and alarm systems and the shortcomings of the existing addressing methods were discussed. A new method of addressing of detectors was proposed. The basic principles of addressing and responding of a called element are stated. Extinguishing module is specific subsystem in classic fire detection and alarm systems. Appearing of addressable fire detection and alarm systems didn't caused essential change in the concept of extinguishing module because of long calling period of such systems. Addressable fire security system based on counting addressing method reaches high calling rates and enables integrating of the extinguishing module in addressable system. Solutions for command addressable element and integrated extinguishing module are given in this paper. The counting addressing method was developed for specific requirements in fire detection and alarm systems, yet its speed and reliability justifies its use in the acquisition of data on slowly variable parameters under industrial conditions. .

90Y -PET imaging: Exploring limitations and accuracy under conditions of low counts and high random fraction

International Nuclear Information System (INIS)

Carlier, Thomas; Willowson, Kathy P.; Fourkal, Eugene; Bailey, Dale L.; Doss, Mohan; Conti, Maurizio

2015-01-01

Purpose: 90 Y -positron emission tomography (PET) imaging is becoming a recognized modality for postinfusion quantitative assessment following radioembolization therapy. However, the extremely low counts and high random fraction associated with 90 Y -PET may significantly impair both qualitative and quantitative results. The aim of this work was to study image quality and noise level in relation to the quantification and bias performance of two types of Siemens PET scanners when imaging 90 Y and to compare experimental results with clinical data from two types of commercially available 90 Y microspheres. Methods: Data were acquired on both Siemens Biograph TruePoint [non-time-of-flight (TOF)] and Biograph microcomputed tomography (mCT) (TOF) PET/CT scanners. The study was conducted in three phases. The first aimed to assess quantification and bias for different reconstruction methods according to random fraction and number of true counts in the scan. The NEMA 1994 PET phantom was filled with water with one cylindrical insert left empty (air) and the other filled with a solution of 90 Y . The phantom was scanned for 60 min in the PET/CT scanner every one or two days. The second phase used the NEMA 2001 PET phantom to derive noise and image quality metrics. The spheres and the background were filled with a 90 Y solution in an 8:1 contrast ratio and four 30 min acquisitions were performed over a one week period. Finally, 32 patient data (8 treated with Therasphere ® and 24 with SIR-Spheres ® ) were retrospectively reconstructed and activity in the whole field of view and the liver was compared to theoretical injected activity. Results: The contribution of both bremsstrahlung and LSO trues was found to be negligible, allowing data to be decay corrected to obtain correct quantification. In general, the recovered activity for all reconstruction methods was stable over the range studied, with a small bias appearing at extremely high random fraction and low counts for

Risk factors associated with low CD4+ lymphocyte count among HIV-positive pregnant women in Nigeria.

Science.gov (United States)

Abimiku, Alash'le; Villalba-Diebold, Pacha; Dadik, Jelpe; Okolo, Felicia; Mang, Edwina; Charurat, Man

2009-09-01

To determine the risk factors for CD4+ lymphocyte counts of 200 cells/mm(3) or lower in HIV-positive pregnant women in Nigeria. A cross-sectional data analysis from a prospective cohort of 515 HIV-positive women attending a prenatal clinic. Risk of a low CD4+ count was estimated using logistic regression analysis. CD4+ lymphocyte counts of 200 cells/mm(3) or lower (280+/-182 cells/mm(3)) were recorded in 187 (36.3%) out of 515 HIV-positive pregnant women included in the study. Low CD4+ count was associated with older age (adjusted odds ratio [aOR] 10.71; 95% confidence interval [CI], 1.20-95.53), lack of condom use (aOR, 5.16; 95% CI, 1.12-23.8), history of genital ulcers (aOR, 1.78; 95% CI, 1.12-2.82), and history of vaginal discharge (aOR; 1.62; 1.06-2.48). Over 35% of the HIV-positive pregnant women had low CD4+ counts, indicating the need for treatment. The findings underscore the need to integrate prevention of mother-to-child transmission with HIV treatment and care, particularly services for sexually transmitted infections.

A low-count reconstruction algorithm for Compton-based prompt gamma imaging

Science.gov (United States)

Huang, Hsuan-Ming; Liu, Chih-Chieh; Jan, Meei-Ling; Lee, Ming-Wei

2018-04-01

The Compton camera is an imaging device which has been proposed to detect prompt gammas (PGs) produced by proton–nuclear interactions within tissue during proton beam irradiation. Compton-based PG imaging has been developed to verify proton ranges because PG rays, particularly characteristic ones, have strong correlations with the distribution of the proton dose. However, accurate image reconstruction from characteristic PGs is challenging because the detector efficiency and resolution are generally low. Our previous study showed that point spread functions can be incorporated into the reconstruction process to improve image resolution. In this study, we proposed a low-count reconstruction algorithm to improve the image quality of a characteristic PG emission by pooling information from other characteristic PG emissions. PGs were simulated from a proton beam irradiated on a water phantom, and a two-stage Compton camera was used for PG detection. The results show that the image quality of the reconstructed characteristic PG emission is improved with our proposed method in contrast to the standard reconstruction method using events from only one characteristic PG emission. For the 4.44 MeV PG rays, both methods can be used to predict the positions of the peak and the distal falloff with a mean accuracy of 2 mm. Moreover, only the proposed method can improve the estimated positions of the peak and the distal falloff of 5.25 MeV PG rays, and a mean accuracy of 2 mm can be reached.

Detection and quantification limits: basic concepts, international harmonization, and outstanding ('low-level') issues

International Nuclear Information System (INIS)

Currie, L.A.

2004-01-01

A brief review is given of concepts, basic definitions, and terminology for metrological detection and quantification capabilities, representing harmonized recommendations and norms of the International Union of Pure and Applied Chemistry (IUPAC) and the International Organization for Standardization (ISO), respectively. Treatment of the (low-level) blank and variance function are discussed in some detail, together with special problems arising with detection decisions and the reporting of low-level data. Key references to the international documents follow, as well as specialized references addressing very low-level counting data, skewed environmental blank distributions, and multiple and multivariate detection decisions

Decay counting in the age of AMS

International Nuclear Information System (INIS)

Arnold, J.R.

1987-01-01

Up to the advent of AMS, all the accomplishments of 14 C dating, and the studies of 10 Be and other long-lived radionuclides, were made by low-level decay counting, the technique pioneered by W.F. Libby. It will hardly be news to people at this conference that, while much was accomplished in the three decades when counting prevailed, the world has now changed decisively. I will try to give an account of where low-level counting was 'before the revolution', and of what its usefulness is today. There are still some remarkable examples of its application, the best being the neutrino experiment of Raymond Davis, and its potential successors. Some cosmogenic nuclides, whose half-lives are less than 10 3 yr, are still best measured by decay; this will continue unless the overall ion yield of AMS systems rises markedly from present levels. One long-lived nuclide, 53 Mn, is still best measured by neutron activation as 312-day 54 Mn, but this may not continue. (orig.)

Decay counting in the age of AMS

International Nuclear Information System (INIS)

Arnold, J.R.

1987-01-01

Up to the advent of AMS, all the accomplishments of 14 C dating, and the studies of 10 Be and other long-lived radionuclides, were made by low-level decay counting, the technique pioneered by W.F. Libby. It will hardly be news to people at this conference that, while much was accomplished in the three decades when counting prevailed, the world has now changed decisively. He will try to give an account of where low-level counting was before the revolution, and of what its usefulness is today. There are still some remarkable examples of its application, the best being the neutrino experiment of Raymond Davis, and its potential successors. Some cosmogenic nuclides, whose half-lives are less than 10 3 yr, are still best measured by decay; this will continue unless the overall ion yield of AMS systems rises markedly from present levels. One long-lived nuclide, 53 Mn, is still best measured by neutron activation as 312-day 54 Mn, but this may not continue

Sensitivity Variation on Low Cycle Fatigue Cracks Using Level 4/Method B Penetrant

Energy Technology Data Exchange (ETDEWEB)

FULWOOD,HARRY; MOORE,DAVID G.

1999-09-02

The Federal Aviation Administration's Airworthiness Assurance NDI Validation Center (AANC) is currently conducting experiments with Level 4, Method B penetrant on low cycle fatigue specimens. The main focus of these experiments is to document the affect on penetrant brightness readings by varying inspection parameters. This paper discusses the results of changing drying temperature, drying time, and dwell time of both penetrant and emulsifier on low cycle fatigue specimens.

An investigation of the trade-off between the count level and image quality in myocardial perfusion SPECT using simulated images: the effects of statistical noise and object variability on defect detectability

International Nuclear Information System (INIS)

He Xin; Links, Jonathan M; Frey, Eric C

2010-01-01

Quantum noise as well as anatomic and uptake variability in patient populations limits observer performance on a defect detection task in myocardial perfusion SPECT (MPS). The goal of this study was to investigate the relative importance of these two effects by varying acquisition time, which determines the count level, and assessing the change in performance on a myocardial perfusion (MP) defect detection task using both mathematical and human observers. We generated ten sets of projections of a simulated patient population with count levels ranging from 1/128 to around 15 times a typical clinical count level to simulate different levels of quantum noise. For the simulated population we modeled variations in patient, heart and defect size, heart orientation and shape, defect location, organ uptake ratio, etc. The projection data were reconstructed using the OS-EM algorithm with no compensation or with attenuation, detector response and scatter compensation (ADS). The images were then post-filtered and reoriented to generate short-axis slices. A channelized Hotelling observer (CHO) was applied to the short-axis images, and the area under the receiver operating characteristics (ROC) curve (AUC) was computed. For each noise level and reconstruction method, we optimized the number of iterations and cutoff frequencies of the Butterworth filter to maximize the AUC. Using the images obtained with the optimal iteration and cutoff frequency and ADS compensation, we performed human observer studies for four count levels to validate the CHO results. Both CHO and human observer studies demonstrated that observer performance was dependent on the relative magnitude of the quantum noise and the patient variation. When the count level was high, the patient variation dominated, and the AUC increased very slowly with changes in the count level for the same level of anatomic variability. When the count level was low, however, quantum noise dominated, and changes in the count level

A matrix-inversion method for gamma-source mapping from gamma-count data - 59082

International Nuclear Information System (INIS)

Bull, Richard K.; Adsley, Ian; Burgess, Claire

2012-01-01

Gamma ray counting is often used to survey the distribution of active waste material in various locations. Ideally the output from such surveys would be a map of the activity of the waste. In this paper a simple matrix-inversion method is presented. This allows an array of gamma-count data to be converted to an array of source activities. For each survey area the response matrix is computed using the gamma-shielding code Microshield [1]. This matrix links the activity array to the count array. The activity array is then obtained via matrix inversion. The method was tested on artificially-created arrays of count-data onto which statistical noise had been added. The method was able to reproduce, quite faithfully, the original activity distribution used to generate the dataset. The method has been applied to a number of practical cases, including the distribution of activated objects in a hot cell and to activated Nimonic springs amongst fuel-element debris in vaults at a nuclear plant. (authors)

A nonlinear wavelet method for data smoothing of low-level gamma-ray spectra

International Nuclear Information System (INIS)

Gang Xiao; Li Deng; Benai Zhang; Jianshi Zhu

2004-01-01

A nonlinear wavelet method was designed for smoothing low-level gamma-ray spectra. The spectra of a 60 Co graduated radioactive source and a mixed soil sample were smoothed respectively according to this method and a 5 point smoothing method. The FWHM of 1,332 keV peak of 60 Co source and the absolute activities of 238 U of soil sample were calculated. The results show that the nonlinear wavelet method is better than the traditional method, with less loss of spectral peak and a more complete reduction of statistical fluctuation. (author)

99Tc atom counting by quadrupole ICP-MS. Optimisation of the instrumental response

International Nuclear Information System (INIS)

Mas, Jose L.; Garcia-Leon, Manuel; Bolivar, Juan P.

2002-01-01

In this paper, an extensive work is done on the specific tune of a conventional ICP-MS for 99 Tc atom counting. For this, two methods have been used and compared: the partial variable control method and the 5D Simplex method. Instrumental limits of detection of 0.2 and 0.8 ppt, respectively, were obtained. They are noticeably lower than that found with the automatic tune method of the spectrometer, 47 ppt, which shows the need of a specific tune when very low levels of 99 Tc have to be determined. A study is presented on the mass interferences for 99 Tc. Our experiments show that the formation of polyatomic atoms or refractory oxides as well as 98 Mo hydrides seem to be irrelevant for 99 Tc atom counting. The opposite occurs with the presence of isobaric interferences, i.e. 99 Ru, and the effect of abundance sensitivity, or low-mass resolution, which can modify the response at m/z=99 to a non-negligible extent

Soil characterization methods for unsaturated low-level waste sites

International Nuclear Information System (INIS)

Wierenga, P.J.; Young, M.H.; Hills, R.G.

1993-01-01

To support a license application for the disposal of low-level radioactive waste (LLW), applicants must characterize the unsaturated zone and demonstrate that waste will not migrate from the facility boundary. This document provides a strategy for developing this characterization plan. It describes principles of contaminant flow and transport, site characterization and monitoring strategies, and data management. It also discusses methods and practices that are currently used to monitor properties and conditions in the soil profile, how these properties influence water and waste migration, and why they are important to the license application. The methods part of the document is divided into sections on laboratory and field-based properties, then further subdivided into the description of methods for determining 18 physical, flow, and transport properties. Because of the availability of detailed procedures in many texts and journal articles, the reader is often directed for details to the available literature. References are made to experiments performed at the Las Cruces Trench site, New Mexico, that support LLW site characterization activities. A major contribution from the Las Cruces study is the experience gained in handling data sets for site characterization and the subsequent use of these data sets in modeling studies

Bioassay method for Uranium in urine by Delay Neutron counting

International Nuclear Information System (INIS)

Suratman; Purwanto; Sukarman-Aminjoyo

1996-01-01

A bioassay method for uranium in urine by neutron counting has been studied. The aim of this research is to obtain a bioassay method for uranium in urine which is used for the determination of internal dose of radiation workers. The bioassay was applied to the artificially uranium contaminated urine. The weight of the contaminant was varied. The uranium in the urine was irradiated in the Kartini reactor core, through pneumatic system. The delayed neutron was counted by BF3 neutron counter. Recovery of the bioassay was between 69.8-88.8 %, standard deviation was less than 10 % and the minimum detection was 0.387 μg

Clustering method for counting passengers getting in a bus with single camera

Science.gov (United States)

Yang, Tao; Zhang, Yanning; Shao, Dapei; Li, Ying

2010-03-01

Automatic counting of passengers is very important for both business and security applications. We present a single-camera-based vision system that is able to count passengers in a highly crowded situation at the entrance of a traffic bus. The unique characteristics of the proposed system include, First, a novel feature-point-tracking- and online clustering-based passenger counting framework, which performs much better than those of background-modeling-and foreground-blob-tracking-based methods. Second, a simple and highly accurate clustering algorithm is developed that projects the high-dimensional feature point trajectories into a 2-D feature space by their appearance and disappearance times and counts the number of people through online clustering. Finally, all test video sequences in the experiment are captured from a real traffic bus in Shanghai, China. The results show that the system can process two 320×240 video sequences at a frame rate of 25 fps simultaneously, and can count passengers reliably in various difficult scenarios with complex interaction and occlusion among people. The method achieves high accuracy rates up to 96.5%.

Radiation counting statistics

Energy Technology Data Exchange (ETDEWEB)

Suh, M. Y.; Jee, K. Y.; Park, K. K.; Park, Y. J.; Kim, W. H

1999-08-01

This report is intended to describe the statistical methods necessary to design and conduct radiation counting experiments and evaluate the data from the experiment. The methods are described for the evaluation of the stability of a counting system and the estimation of the precision of counting data by application of probability distribution models. The methods for the determination of the uncertainty of the results calculated from the number of counts, as well as various statistical methods for the reduction of counting error are also described. (Author). 11 refs., 8 tabs., 8 figs.

Radiation counting statistics

Energy Technology Data Exchange (ETDEWEB)

Suh, M. Y.; Jee, K. Y.; Park, K. K. [Korea Atomic Energy Research Institute, Taejon (Korea)

1999-08-01

This report is intended to describe the statistical methods necessary to design and conduct radiation counting experiments and evaluate the data from the experiments. The methods are described for the evaluation of the stability of a counting system and the estimation of the precision of counting data by application of probability distribution models. The methods for the determination of the uncertainty of the results calculated from the number of counts, as well as various statistical methods for the reduction of counting error are also described. 11 refs., 6 figs., 8 tabs. (Author)

Radiation counting statistics

International Nuclear Information System (INIS)

Suh, M. Y.; Jee, K. Y.; Park, K. K.; Park, Y. J.; Kim, W. H.

1999-08-01

This report is intended to describe the statistical methods necessary to design and conduct radiation counting experiments and evaluate the data from the experiment. The methods are described for the evaluation of the stability of a counting system and the estimation of the precision of counting data by application of probability distribution models. The methods for the determination of the uncertainty of the results calculated from the number of counts, as well as various statistical methods for the reduction of counting error are also described. (Author). 11 refs., 8 tabs., 8 figs

Combustion water purification techniques influence on OBT analysing using liquid scintillation counting method

International Nuclear Information System (INIS)

Varlam, C.; Vagner, I.; Faurescu, I.; Faurescu, D.

2015-01-01

In order to determine organically bound tritium (OBT) from environmental samples, these must be converted into water, measurable by liquid scintillation counting (LSC). For this purpose we conducted some experiments to determine OBT level of a grass sample collected from an uncontaminated area. The studied grass sample was combusted in a Parr bomb. However usual interfering phenomena were identified: color or chemical quench, chemiluminescence, overlap over tritium spectrum because of other radionuclides presence as impurities ( 14 C from organically compounds, 36 Cl as chloride and free chlorine, 40 K as potassium cations) and emulsion separation. So the purification of the combustion water before scintillation counting appeared to be essential. 5 purification methods were tested: distillation with chemical treatment (Na 2 O 2 and KMnO 4 ), lyophilization, chemical treatment (Na 2 O 2 and KMnO 4 ) followed by lyophilization, azeotropic distillation with toluene and treatment with a volcanic tuff followed by lyophilization. After the purification step each sample was measured and the OBT measured concentration, together with physico-chemical analysis of the water analyzed, revealed that the most efficient method applied for purification of the combustion water was the method using chemical treatment followed by lyophilization

Licensing of alternative methods of disposal of low-level radioactive waste: Branch technical position, Low-Level Waste Licensing Branch

International Nuclear Information System (INIS)

Higginbotham, L.B.; Dragonette, K.S.; Pittiglio, C.L. Jr.

1986-12-01

This branch technical position statement identifies and describes specific methods of disposal currently being considered as alternatives to shallow land burial, provides general guidance on these methods of disposal, and recommends procedures that will improve and simplify the licensing process. The statement provides answers to certain questions that have arisen regarding the applicability of 10 CFR 61 to near-surface disposal of waste, using methods that incorporate engineered barriers or structures, and other alternatives to conventional shallow land burial disposal practices. This position also identifies a recently published NRC contractor report that addresses the applicability of 10 CFR 61 to a range of generic disposal concepts and which provides technical guidance that the staff intends to use for these concepts. This position statement combined with the above-mentioned NRC contractor report fulfills the requirements of Section 8(a) of Public Law 99-240, the Low-Level Radioactive Waste Policy Amendments Act of 1985

Processing of low-level wastes

International Nuclear Information System (INIS)

Vance, J.N.

1986-01-01

Although low-level wastes have been generated and have required processing for more than two decades now, it is noteworthy that processing methods are continuing to change. The changes are not only attributable to improvements in technology, but are also the result of changing regulations and economics and uncertainties regarding the future availabilities of burial space for disposal. Indeed, because of the changes which have and are taking place in the processing of low-level waste, an overview of the current situation is in order. This presentation is a brief overview of the processing methods generally employed to treat the low-level wastes generated from both fuel cycle and non-fuel cycle sources. The presentation is far too brief to deal with the processing technologies in a comprehensive fashion, but does provide a snapshot of what the current or typical processing methods are and what changes are occurring and why

Study on serum TNF-α level, B-cell count and T-cell subsets distribution in peripheral blood in patients with rheumatoid arthritis

International Nuclear Information System (INIS)

Shi Buqing

2006-01-01

Objective: To study the changes of serum TNF-α levels, B-cell count and T-cell subsets distribution in peripheral blood in patients with rheumatoid arthritis. Methods: Serum TNF-α levels (with RIA), B cell as well as T cell subsets distribution type (with monoclonal antibody technique) were examined in 37 patients with rheumatoid arthritis and 30 controls. Results Serum TNF-α levels and B lymphocytes count were significantly higher in the patients than those in controls (P 3 , CD 4 and CD 4 /CD 8 were obviously lower (P<0.01). Conclusion: Rheumatoid arthritis is an autoimmune disease with abnormal immunoregulation. (authors)

Water quality - Determination of tritium activity concentration - Liquid scintillation counting method (International Standard Publication ISO 9698:1989)

International Nuclear Information System (INIS)

Stefanik, J.

1999-01-01

This International Standard specifies a method for the determination of tritiated water ([ 3 H]H 2 O) activity concentration in water by liquid scintillation counting. The method is applicable to all types of water including seawater with tritium activity concentrations of up to 10 6 Bq/m 3 when using 20 ml counting vials. Below tritium activity concentrations of about 5 x 10 4 Bq/m 3[ 8], a prior enrichment step and/or the measurement of larger sample volumes can significantly improve the accuracy of the determination and lower the limit of detection. Tritium activity concentrations higher than 10 6 Bq/m 3 may be determined after appropriate dilution with distilled water of proven low tritium content. An alternative method for the determination of these higher activities involves increasing the tritium activity concentrations of the internal standard solution. The method is not applicable to the analysis of organically bound tritium; its determination requires an oxidative digestion

Comparison of approximate formulas for decision levels and detection limits for paired counting with the exact results

International Nuclear Information System (INIS)

Potter, W.E.

2005-01-01

The exact probability density function for paired counting can be expressed in terms of modified Bessel functions of integral order when the expected blank count is known. Exact decision levels and detection limits can be computed in a straightforward manner. For many applications perturbing half-integer corrections to Gaussian distributions yields satisfactory results for decision levels. When there is concern about the uncertainty for the expected value of the blank count, a way to bound the errors of both types using confidence intervals for the expected blank count is discussed. (author)

Neutron radiography imaging with 2-dimensional photon counting method and its problems

International Nuclear Information System (INIS)

Ikeda, Y.; Kobayashi, H.; Niwa, T.; Kataoka, T.

1988-01-01

A ultra sensitive neutron imaging system has been deviced with a 2-dimensional photon counting camara (ARGUS 100). The imaging system is composed by a 2-dimensional single photon counting tube and a low background vidicon followed with an image processing unit and frame memories. By using the imaging system, electronic neutron radiography (NTV) has been possible under the neutron flux less than 3 x 10 4 n/cm 2 ·s. (author)

Fractal analysis of mandibular trabecular bone: optimal tile sizes for the tile counting method.

Science.gov (United States)

Huh, Kyung-Hoe; Baik, Jee-Seon; Yi, Won-Jin; Heo, Min-Suk; Lee, Sam-Sun; Choi, Soon-Chul; Lee, Sun-Bok; Lee, Seung-Pyo

2011-06-01

This study was performed to determine the optimal tile size for the fractal dimension of the mandibular trabecular bone using a tile counting method. Digital intraoral radiographic images were obtained at the mandibular angle, molar, premolar, and incisor regions of 29 human dry mandibles. After preprocessing, the parameters representing morphometric characteristics of the trabecular bone were calculated. The fractal dimensions of the processed images were analyzed in various tile sizes by the tile counting method. The optimal range of tile size was 0.132 mm to 0.396 mm for the fractal dimension using the tile counting method. The sizes were closely related to the morphometric parameters. The fractal dimension of mandibular trabecular bone, as calculated with the tile counting method, can be best characterized with a range of tile sizes from 0.132 to 0.396 mm.

Multiple-Event, Single-Photon Counting Imaging Sensor

Science.gov (United States)

Zheng, Xinyu; Cunningham, Thomas J.; Sun, Chao; Wang, Kang L.

2011-01-01

The single-photon counting imaging sensor is typically an array of silicon Geiger-mode avalanche photodiodes that are monolithically integrated with CMOS (complementary metal oxide semiconductor) readout, signal processing, and addressing circuits located in each pixel and the peripheral area of the chip. The major problem is its single-event method for photon count number registration. A single-event single-photon counting imaging array only allows registration of up to one photon count in each of its pixels during a frame time, i.e., the interval between two successive pixel reset operations. Since the frame time can t be too short, this will lead to very low dynamic range and make the sensor merely useful for very low flux environments. The second problem of the prior technique is a limited fill factor resulting from consumption of chip area by the monolithically integrated CMOS readout in pixels. The resulting low photon collection efficiency will substantially ruin any benefit gained from the very sensitive single-photon counting detection. The single-photon counting imaging sensor developed in this work has a novel multiple-event architecture, which allows each of its pixels to register as more than one million (or more) photon-counting events during a frame time. Because of a consequently boosted dynamic range, the imaging array of the invention is capable of performing single-photon counting under ultra-low light through high-flux environments. On the other hand, since the multiple-event architecture is implemented in a hybrid structure, back-illumination and close-to-unity fill factor can be realized, and maximized quantum efficiency can also be achieved in the detector array.

(90)Y -PET imaging: Exploring limitations and accuracy under conditions of low counts and high random fraction.

Science.gov (United States)

Carlier, Thomas; Willowson, Kathy P; Fourkal, Eugene; Bailey, Dale L; Doss, Mohan; Conti, Maurizio

2015-07-01

(90)Y -positron emission tomography (PET) imaging is becoming a recognized modality for postinfusion quantitative assessment following radioembolization therapy. However, the extremely low counts and high random fraction associated with (90)Y -PET may significantly impair both qualitative and quantitative results. The aim of this work was to study image quality and noise level in relation to the quantification and bias performance of two types of Siemens PET scanners when imaging (90)Y and to compare experimental results with clinical data from two types of commercially available (90)Y microspheres. Data were acquired on both Siemens Biograph TruePoint [non-time-of-flight (TOF)] and Biograph microcomputed tomography (mCT) (TOF) PET/CT scanners. The study was conducted in three phases. The first aimed to assess quantification and bias for different reconstruction methods according to random fraction and number of true counts in the scan. The NEMA 1994 PET phantom was filled with water with one cylindrical insert left empty (air) and the other filled with a solution of (90)Y . The phantom was scanned for 60 min in the PET/CT scanner every one or two days. The second phase used the NEMA 2001 PET phantom to derive noise and image quality metrics. The spheres and the background were filled with a (90)Y solution in an 8:1 contrast ratio and four 30 min acquisitions were performed over a one week period. Finally, 32 patient data (8 treated with Therasphere(®) and 24 with SIR-Spheres(®)) were retrospectively reconstructed and activity in the whole field of view and the liver was compared to theoretical injected activity. The contribution of both bremsstrahlung and LSO trues was found to be negligible, allowing data to be decay corrected to obtain correct quantification. In general, the recovered activity for all reconstruction methods was stable over the range studied, with a small bias appearing at extremely high random fraction and low counts for iterative algorithms

Liquid scintillation counting of chlorophyll

International Nuclear Information System (INIS)

Fric, F.; Horickova, B.; Haspel-Horvatovic, E.

1975-01-01

A precise and reproducible method of liquid scintillation counting was worked out for measuring the radioactivity of 14 C-labelled chlorophyll a and chlorophyll b solutions without previous bleaching. The spurious count rate caused by luminescence of the scintillant-chlorophyll system is eliminated by using a suitable scintillant and by measuring the radioactivity at 4 to 8 0 C after an appropriate time of dark adaptation. Bleaching of the chlorophyll solutions is necessary only for measuring of very low radioactivity. (author)

Limits of reliability for the measurement of integral count

International Nuclear Information System (INIS)

Erbeszkorn, L.

1979-01-01

A method is presented for exact and approximate calculation of reliability limits of measured nuclear integral count. The formulae are applicable in measuring conditions which assure the Poisson distribution of the counts. The coefficients of the approximate formulae for 90, 95, 98 and 99 per cent reliability levels are given. The exact reliability limits for 90 per cent reliability level are calculated up to 80 integral counts. (R.J.)

Quality control of radiation counting systems and measurement of minimum detectable activity

International Nuclear Information System (INIS)

Song, Byoung Chul; Han, Sung Sim; Kim, Young Bok; Jee, Kwang Yong; Sohn, Se Chul

2004-01-01

Various radiation counters have been using to determine radioactivity of radwastes for disposal. A radiation counting system was set up using a radiation detector chosen in this study and its stability was investigated through the periodic determination of background and counting efficiencies in accordance with a quality control program to increase the confidence level. The average background level for the γ-spectrometer was 1.59 cps and the average counting level for the standard sample was 45248 dps within 20 confidence levels. The average alpha background level for the low background α/β counting system was 0.31 cpm and the efficiency for alpha counting was 34.38 %. The average beta background level for the α/β counting system was 1.30 cpm and the efficiency for beta counting was 46.5%. The background level in the region of 3H and 14C for the liquid scintillation counting system was 2.52 and 3.31 cpm and the efficiency for alpha counting was 58.5 and 95.6%, respectively. The minimum detectable activity for the γ-spectrometer was found to be 3.2 Bq/mL and 3.8 Bq/mL for the liquid scintillation counter, and 20.5 and 23.0 Bq/mL, respectively for the α and β counting system

The measurement of 222Rn in drinking water by low-level liquid scintillation counting

International Nuclear Information System (INIS)

Barnett, J.M.; McKlveen, J.W.

1992-01-01

Radon-222 (Rn) has universally been found in well water. Non-stagnant ground water is collected at the well head while the well is pumping. The water is adjusted to a slow, non-aerated, steady flow through a clear tube, and a 500 ml glass bottle is filled. The sample is tightly capped after a high meniscus has developed. In the laboratory, standard 22 ml glass vials are filled with 10 ml of a toluene based mineral oil LS cocktail. Then, two 5 ml sample aliquots are pipetted into the vial. Vials are capped tightly, shaken vigorously, and placed in the liquid scintillation (LS) counter. Secular equilibrium is established in approximately 4 hours, after which samples are counted for 100 minutes each. The counting efficiency for Rn and progeny ranges between 315 to 345 percent depending on the chosen spectral window. The average background is about 6 cpm. A total of 28 wells were tested for Rn in the Carefree-Cave Creek, Arizone, USA area. The area's geometric average Rn concentration was found to be 46.5 Bq*1 -1 . The associated estimated lung dose is 0.51 mSv*y -1 . (author) 8 refs.; 1 fig.; 1 tab

17 CFR 275.203(b)(3)-2 - Methods for counting clients in certain private funds.

Science.gov (United States)

2010-04-01

... 17 Commodity and Securities Exchanges 3 2010-04-01 2010-04-01 false Methods for counting clients....203(b)(3)-2 Methods for counting clients in certain private funds. (a) For purposes of section 203(b)(3) of the Act (15 U.S.C. 80b-3(b)(3)), you must count as clients the shareholders, limited partners...

An automated NaI 'well' counting system for the determination of radiocaesium

International Nuclear Information System (INIS)

Andrews, D.J.; Sutton, G.A.

1993-01-01

During the past five years the number of sea and freshwater samples collected by the (DFR) for radiocaesium analysis has increased significantly due to the extended monitoring programme following the Chernobyl accident. Counting times have increased because of the general reduction in levels of radioactivity following the introduction of a new effluent-treatment plant at British Nuclear Fuels's reprocessing plant at Sellafield. The large number of samples and the low levels of radioactivity have resulted in the requirement for an additional, highly sensitive, gamma counting system. This paper describes the design and development of an improved automated gamma counting system suitable for the determination of low levels of radiocaesium activity in these samples. (author)

High-sensitivity measurements for low-level TRU wastes using advanced passive neutron techniques

International Nuclear Information System (INIS)

Menlove, H.O.; Eccleston, G.W.

1992-01-01

In recent years, both passive- and active-neutron nondestructive assay (NDA) systems have been used to measure the uranium and plutonium content in 200-ell drums. Because of the heterogeneity of the wastes, representative sampling is not possible and NDA methods are preferred over destructive analysis. Active-neutron assay systems are used to measure the fissile isotopes such as 235 U, 23 Pu, and 241 Pu; the isotopic ratios are used to infer the total plutonium content and thus the specific disintegration rate. The active systems include 14-MeV-neutron (DT) generators with delayed-neutron counting, (D,T) generators with the differential die-away technique, and 252 Cf delayed-neutron shufflers. Passive assay systems (for example, segmented gamma-ray scanners)5 have used gamma-ray sessions, while others (for example, passive drum counters) used passive-neutron signals. We have developed a new passive-neutron measurement technique to improve the accuracy and sensitivity of the NDA of plutonium scrap and waste. This new 200-ell-drum assay system combines the classical NDA method of counting passive-neutron totals and coincidences from plutonium with the new features of ''add-a-source'' (AS) and multiplicity counting to improve the accuracy of matrix corrections and statistical techniques that improve the low-level detectability limits. This paper describes the improvements we have made in passive-neutron assay systems and compares the accuracies and detectability limits of passive- and active-neutron assay systems

Alternative methods for dispoal of low-level radioactive wastes. Task 1. Description of methods and assessment of criteria

International Nuclear Information System (INIS)

Bennett, R.D.; Miller, W.O.; Warriner, J.B.; Malone, P.G.; McAneny, C.C.

1984-04-01

The study reported herein contains the results of Task 1 of a four-task study entitled Criteria for Evaluating Engineered Facilities. The overall objective of this study is to ensure that the criteria needed to evaluate five alternative low-level radioactive waste (LLW) disposal methods are available to the Nuclear Regulatory Commission (NRC) and the Agreement States. The alternative methods considered are belowground vaults, aboveground vaults, earth mounded concrete bunkers, mined cavities, and augered holes. Each of these alternatives is either being used by other countries for low-level radioactive waste (LLW) disposal or is being considered by other countries or US agencies. In this report the performance requirements are listed, each alternative is described, the experience gained with its use is discussed, and the performance capabilities of each method are addressed. Next, the existing 10 CFR Part 61 Subpart D criteria with respect to paragraphs 61.50 through 61.53, pertaining to site suitability, design, operations and closure, and monitoring are assessed for applicability to evaluation of each alternative. Preliminary conclusions and recommendations are offered on each method's suitability as an LLW disposal alternative, the applicability of the criteria, and the need for supplemental or modified criteria

Low background gas flow beta counting system [Paper No.:M2

International Nuclear Information System (INIS)

Abani, M.C.; Anilkumar, S.; Bhende, D.R.; Krishnan, Narayani; Babu, D.A.R.

1993-01-01

It is difficult to count beta samples of low specific activity in conventional types of counting systems which have inherently high background. This is specially true in case of environmental samples. A gas flow type beta counter has been developed which have the twin advantage of high efficiency and low background. This system uses a gas flow type main counter and another gas flow type guard counter working on the same principle in anticoincidence mode. Both counters are operated in G.M. region. With this anticoincidence arrangement and lead shielding of 3 inch, the system has the background of the order of 1 cpm and efficiency of 40% for 40 K beta and 14% for 14 C beta. The electronics developed includes a quenching cum coincidence-anticoincidence unit, EHT and a counter timer. This paper describes in detail the development and operational experience with the system. A number of units are already operational at BARC and at Environmental Survey Laboratories set up by Department of Atomic Energy and at various other institutions. (author). 4 refs., 2 figs

Two reports: (i) Correlation properties of delayed neutrons from fast neutron induced fission. (ii) Method and set-up for measurements of trace level content of heavy fissionable elements based on delayed neutron counting

International Nuclear Information System (INIS)

Piksaikin, V.M.; Isaev, S.G.; Goverdovski, A.A.; Pshakin, G.M.

1998-10-01

The document includes the following two reports: 'Correlation properties of delayed neutrons from fast neutron induced fission' and 'Method and set-up for measurements of trace level content of heavy fissionable elements based on delayed neutron counting. A separate abstract was prepared for each report

Power distribution and substrate noise coupling investigations on the behavioral level for photon counting imaging readout circuits

International Nuclear Information System (INIS)

Lundgren, Jan; Abdalla, Suliman; O'Nils, Mattias; Oelmann, Bengt

2007-01-01

In modern mixed-signal system design, there are increasing problems associated with noise coupling caused by switching digital parts to sensitive analog parts. As a consequence, there is a growing necessity to understand these problems. In order to avoid costly design iterations, noise coupling simulations should be initiated as early as possible in the design chain. The problems associated with on-chip noise coupling have been discovered in photon counting pixel detector readout systems, where the level of integration of analog and digital circuits is very high on a very small area, and it would appear that these problems will continue to increase for future system designs in this field. This paper deals with the functionality of utilizing behavioral level models for simulating noise coupling in these readout systems. The methods and models are described and simulation results are shown for a photon counting pixel detector readout system

Quality control methods in accelerometer data processing: identifying extreme counts.

Directory of Open Access Journals (Sweden)

Carly Rich

Full Text Available Accelerometers are designed to measure plausible human activity, however extremely high count values (EHCV have been recorded in large-scale studies. Using population data, we develop methodological principles for establishing an EHCV threshold, propose a threshold to define EHCV in the ActiGraph GT1M, determine occurrences of EHCV in a large-scale study, identify device-specific error values, and investigate the influence of varying EHCV thresholds on daily vigorous PA (VPA.We estimated quantiles to analyse the distribution of all accelerometer positive count values obtained from 9005 seven-year old children participating in the UK Millennium Cohort Study. A threshold to identify EHCV was derived by differentiating the quantile function. Data were screened for device-specific error count values and EHCV, and a sensitivity analysis conducted to compare daily VPA estimates using three approaches to accounting for EHCV.Using our proposed threshold of ≥ 11,715 counts/minute to identify EHCV, we found that only 0.7% of all non-zero counts measured in MCS children were EHCV; in 99.7% of these children, EHCV comprised < 1% of total non-zero counts. Only 11 MCS children (0.12% of sample returned accelerometers that contained negative counts; out of 237 such values, 211 counts were equal to -32,768 in one child. The medians of daily minutes spent in VPA obtained without excluding EHCV, and when using a higher threshold (≥19,442 counts/minute were, respectively, 6.2% and 4.6% higher than when using our threshold (6.5 minutes; p<0.0001.Quality control processes should be undertaken during accelerometer fieldwork and prior to analysing data to identify monitors recording error values and EHCV. The proposed threshold will improve the validity of VPA estimates in children's studies using the ActiGraph GT1M by ensuring only plausible data are analysed. These methods can be applied to define appropriate EHCV thresholds for different accelerometer models.

Low-level radioactive waste treatment technology. Low-level radioactive waste management handbook series

International Nuclear Information System (INIS)

1984-07-01

Each generator of low-level radioactive waste must consider three sequential questions: (1) can the waste in its as-generated form be packaged and shipped to a disposal facility; (2) will the packaged waste be acceptable for disposal; and (3) if so, is it cost effective to dispose of the waste in its as-generated form. These questions are aimed at determining if the waste form, physical and chemical characteristics, and radionuclide content collectively are suitable for shipment and disposal in a cost-effective manner. If not, the waste management procedures will involve processing operations in addition to collection, segregation, packaging, shipment, and disposal. This handbook addresses methods of treating and conditioning low-level radioactive waste for shipment and disposal. A framework is provided for selection of cost-effective waste-processing options for generic categories of low-level radioactive waste. The handbook is intended as a decision-making guide that identifies types of information required to evaluate options, methods of evaluation, and limitations associated with selection of any of the processing options

Maple syrup analysis for 137Cs, K, and B, using a low-background counting system and PGAA

International Nuclear Information System (INIS)

Anderson, D.L.; Cunningham, W.C.

1994-01-01

Fifteen maple syrups were analyzed for 137 Cs and K (via 40 K) by using a low-background γ-ray counting system, and for B and K by using neutron capture prompt γ-ray activation analysis (PGAA). For low-background γ-ray counting, 3 ο limits of detection (24-hour counts) were 0.03 Bq 137 Cs/kg and 10 mg K/kg for 3.5-L portions and 0.08 Bq 137 Cs/kg and 20 mg K/kg for 1.0-L portions. K concentrations determined by the two methods (using 2-g portions for PGAA) were in excellent agreement. The products were obtained in 1991, with one produced in Maryland, three in New York, four in Pennsylvania, two in New Hampshire, and five in Canada. The average activity concentration for Canadian syrups (2.8 Bq 137 Cs/kg) was nearly a factor 20 greater than the average (0.15 Bq 137 Cs/kg) for the other syrups, but all 137 Cs activity concentrations were at least 100 times lower than those for which controls would be recommended according to Federal Radiation Council guidance. The data exhibited distinct groupings related to the sources of the products when the ratios 137 Cs activity to K content (Bq Cs /mg K ) were plotted vs. B concentrations. (author). 15 refs., 3 figs., 1 tab

Combustion water purification techniques influence on OBT analysing using liquid scintillation counting method

Energy Technology Data Exchange (ETDEWEB)

Varlam, C.; Vagner, I.; Faurescu, I.; Faurescu, D. [National Institute for Cryogenics and Isotopic Technologies, Valcea (Romania)

2015-03-15

In order to determine organically bound tritium (OBT) from environmental samples, these must be converted into water, measurable by liquid scintillation counting (LSC). For this purpose we conducted some experiments to determine OBT level of a grass sample collected from an uncontaminated area. The studied grass sample was combusted in a Parr bomb. However usual interfering phenomena were identified: color or chemical quench, chemiluminescence, overlap over tritium spectrum because of other radionuclides presence as impurities ({sup 14}C from organically compounds, {sup 36}Cl as chloride and free chlorine, {sup 40}K as potassium cations) and emulsion separation. So the purification of the combustion water before scintillation counting appeared to be essential. 5 purification methods were tested: distillation with chemical treatment (Na{sub 2}O{sub 2} and KMnO{sub 4}), lyophilization, chemical treatment (Na{sub 2}O{sub 2} and KMnO{sub 4}) followed by lyophilization, azeotropic distillation with toluene and treatment with a volcanic tuff followed by lyophilization. After the purification step each sample was measured and the OBT measured concentration, together with physico-chemical analysis of the water analyzed, revealed that the most efficient method applied for purification of the combustion water was the method using chemical treatment followed by lyophilization.

{sup 90}Sr in human excretion samples. Comparison of MC-ICP-MS and conventional low-level beta-counting; {sup 90}Sr in menschlichen Ausscheidungsproben. Vergleich zwischen MC-ICP-MS und konventioneller Low Level Beta-Messung

Energy Technology Data Exchange (ETDEWEB)

Burow, M.; Schumacher, C.; Zoriy, M. [Forschungszentrum Juelich GmbH (Germany). Geschaeftsbereich fuer Sicherheit und Strahlenschutz

2016-07-01

At the present for determination of {sup 90}Sr in different human excretion samples manly radiochemical methods are applied, for example LL-beta- counter or liquid scintillation method. These methods require an isolation of strontium from other interfering radioactive species such as e.g. lead, polonium, plutonium, neptunium and potassium (for example, separation on Sr Resin, Fa. Eichrom, France) and afterwards long counting time restrict the usage in some application fields. On the other hand, the liquid scintillation techniques that may be used for detection present a challenge in the analysis of {sup 90}Sr in the presence of {sup 90}Y. However spectra of both radionuclides overlap in a certain zone and this may be resolved by mathematical calculations of {sup 90}Y ingrowth or by simply waiting for radiochemical equilibrium to be reached (2-3 weeks). In the case of emergency, monitoring of operating personal or civil population for possible incorporation of {sup 90}Sr via excretion samples a readily available, faster and reliable analytical procedure may prove to be of great importance. For these purposes, an analytical method for the determination of {sup 90}Sr in urine with high-sensitive MC-ICP-MS was developed in the radiochemical laboratory of the Department for Safety and Radiation Protection. The method was optimized to avoid a multitude of isobaric interferences that occur on m/z 90 using a cold-plasma operation condition of ICP-MS. The reported LOD as low as 0,3-1 Bq/l in the water samples was found to be acceptable for majority of our analytical tasks.

Packaged low-level waste verification system

International Nuclear Information System (INIS)

Tuite, K.T.; Winberg, M.; Flores, A.Y.; Killian, E.W.; McIsaac, C.V.

1996-01-01

Currently, states and low-level radioactive waste (LLW) disposal site operators have no method of independently verifying the radionuclide content of packaged LLW that arrive at disposal sites for disposal. At this time, disposal sites rely on LLW generator shipping manifests and accompanying records to insure that LLW received meets the waste acceptance criteria. An independent verification system would provide a method of checking generator LLW characterization methods and help ensure that LLW disposed of at disposal facilities meets requirements. The Mobile Low-Level Waste Verification System (MLLWVS) provides the equipment, software, and methods to enable the independent verification of LLW shipping records to insure that disposal site waste acceptance criteria are being met. The MLLWVS system was developed under a cost share subcontract between WMG, Inc., and Lockheed Martin Idaho Technologies through the Department of Energy's National Low-Level Waste Management Program at the Idaho National Engineering Laboratory (INEL)

The extraction of lifetimes of weakly-populated nuclear levels in recoil distance method experiments

International Nuclear Information System (INIS)

Kennedy, D.L.; Stuchbery, A.E.; Bolotin, H.H.

1979-01-01

Two analytic techniques are described which extend the conventional analysis of recoil-distance method (RDM) data. The first technique utilizes the enhanced counting statistics of the composite spectrum formed by the addition of all γ-ray spectra recorded at the different target-to-stopper distances employed, in order to extract the lifetimes of levels whose observed depopulating γ-ray transitions have insufficient statistics to permit conventional analysis. The second technique analyses peak centroids rather than peak areas to account for contamination by flight distance dependent background. The results from a recent study of the low-lying excited states in 196 198 Pt for those levels whose lifetimes could be extracted by conventional RDM analysis are shown to be in good agreement with those obtained using the new methods of analysis

Direct reconstruction of parametric images for brain PET with event-by-event motion correction: evaluation in two tracers across count levels

Science.gov (United States)

Germino, Mary; Gallezot, Jean-Dominque; Yan, Jianhua; Carson, Richard E.

2017-07-01

Parametric images for dynamic positron emission tomography (PET) are typically generated by an indirect method, i.e. reconstructing a time series of emission images, then fitting a kinetic model to each voxel time activity curve. Alternatively, ‘direct reconstruction’, incorporates the kinetic model into the reconstruction algorithm itself, directly producing parametric images from projection data. Direct reconstruction has been shown to achieve parametric images with lower standard error than the indirect method. Here, we present direct reconstruction for brain PET using event-by-event motion correction of list-mode data, applied to two tracers. Event-by-event motion correction was implemented for direct reconstruction in the Parametric Motion-compensation OSEM List-mode Algorithm for Resolution-recovery reconstruction. The direct implementation was tested on simulated and human datasets with tracers [11C]AFM (serotonin transporter) and [11C]UCB-J (synaptic density), which follow the 1-tissue compartment model. Rigid head motion was tracked with the Vicra system. Parametric images of K 1 and distribution volume (V T  =  K 1/k 2) were compared to those generated by the indirect method by regional coefficient of variation (CoV). Performance across count levels was assessed using sub-sampled datasets. For simulated and real datasets at high counts, the two methods estimated K 1 and V T with comparable accuracy. At lower count levels, the direct method was substantially more robust to outliers than the indirect method. Compared to the indirect method, direct reconstruction reduced regional K 1 CoV by 35-48% (simulated dataset), 39-43% ([11C]AFM dataset) and 30-36% ([11C]UCB-J dataset) across count levels (averaged over regions at matched iteration); V T CoV was reduced by 51-58%, 54-60% and 30-46%, respectively. Motion correction played an important role in the dataset with larger motion: correction increased regional V T by 51% on average in the [11C

Counting probe

International Nuclear Information System (INIS)

Matsumoto, Haruya; Kaya, Nobuyuki; Yuasa, Kazuhiro; Hayashi, Tomoaki

1976-01-01

Electron counting method has been devised and experimented for the purpose of measuring electron temperature and density, the most fundamental quantities to represent plasma conditions. Electron counting is a method to count the electrons in plasma directly by equipping a probe with the secondary electron multiplier. It has three advantages of adjustable sensitivity, high sensitivity of the secondary electron multiplier, and directional property. Sensitivity adjustment is performed by changing the size of collecting hole (pin hole) on the incident front of the multiplier. The probe is usable as a direct reading thermometer of electron temperature because it requires to collect very small amount of electrons, thus it doesn't disturb the surrounding plasma, and the narrow sweep width of the probe voltage is enough. Therefore it can measure anisotropy more sensitively than a Langmuir probe, and it can be used for very low density plasma. Though many problems remain on anisotropy, computer simulation has been carried out. Also it is planned to provide a Helmholtz coil in the vacuum chamber to eliminate the effect of earth magnetic field. In practical experiments, the measurement with a Langmuir probe and an emission probe mounted to the movable structure, the comparison with the results obtained in reverse magnetic field by using a Helmholtz coil, and the measurement of ionic sound wave are scheduled. (Wakatsuki, Y.)

The performance of photon counting imaging with a Geiger mode silicon avalanche photodiode

International Nuclear Information System (INIS)

Qu, Hui-Ming; Zhang, Yi-Fan; Ji, Zhong-Jie; Chen, Qian

2013-01-01

In principle, photon counting imaging can detect a photon. With the development of low-level-light image intensifier techniques and low-level-light detection devices, photon counting imaging can now detect photon images under extremely low illumination. Based on a Geiger mode silicon avalanche photodiode single photon counter, an experimental system for photon counting imaging was built through two-dimensional scanning of a SPAD (single photon avalanche diode) detector. The feasibility of the imaging platform was validated experimentally. Two images with different characteristics, namely, the USAF 1951 resolution test panel and the image of Lena, were chosen to evaluate the imaging performance of the experimental system. The results were compared and analysed. The imaging properties under various illumination and scanning steps were studied. The lowest illumination limit of the SPAD photon counting imaging was determined. (letter)

Novel Detecting Methods of Shack-Hartmann Wavefront Sensor at Low Light Levels

International Nuclear Information System (INIS)

Zhang, A; Rao, C H; Zhang, Y D; Jiang, W H

2006-01-01

A study of novel detecting methods of Shack-Hartmann wavefront sensor at low light levels has been made. Three methods of images processing before slope estimating are presented: Linear Enhancing (LE), Exponential Enhancing (EE) and Fourier Spectrum Filtering (FSF). The idea of LE method is to time the image intensity with a special coefficient before slope estimation. The image points are powered by a selected exponent in EE method. The FSF method is based on the spectrum difference between signal and noise. Most of noise spectrum is filtered and the noise is restrained. The simulated and experimental results show that the LE method does not work effectively, and the other two methods can improve the slope estimation when the Signal-to-noise ratio is higher than 3.0. When the Signal-to-noise ratio is less than 3.0, especially when it is less than 1.0, the FSF is the only method that can overcome the readout noise of the CCD detector

NMT - A new individual ion counting method: Comparison to a Faraday cup

Science.gov (United States)

Burton, Michael; Gorbunov, Boris

2018-03-01

Two sample detectors used to analyze the emission from Gas Chromatography (GC) columns are the Flame Ionization Detector (FID) and the Electron Capture Detector (ECD). Both of these detectors involve ionization of the sample molecules and then measuring electric current in the gas using a Faraday cup. In this paper a newly discovered method of ion counting, Nanotechnology Molecular Tagging (NMT) is tested as a replacement to the Faraday cup in GCs. In this method the effective physical volume of individual molecules is enlarged up to 1 billion times enabling them to be detected by an optical particle counter. It was found that the sensitivity of NMT was considerably greater than the Faraday cup. The background in the NMT was circa 200 ions per cm3, corresponding to an extremely low electric current ∼10-17 A.

A Bayesian interpretation of a decision level in radioactivity counting data

International Nuclear Information System (INIS)

Moreno, A.; Navarro, E.; Senent, F.

1988-01-01

A Bayesian procedure is applied to derive a posterior gamma distribution which describes the inferential content of the radsioactivity counting data without incorporating any other information. A formulation leading to both dsetection and decision limits is developed. A tabulation of significance levels is given for some experimental situations. (Author)

Effect of the carbohydrate counting method on glycemic control in patients with type 1 diabetes

Directory of Open Access Journals (Sweden)

Dias Viviane M

2010-08-01

Full Text Available Abstract Background The importance of achieving and maintaining an appropriate metabolic control in patients with type 1 diabetes mellitus (DM1 has been established in many studies aiming to prevent the development of chronic complications. The carbohydrate counting method can be recommended as an additional tool in the nutritional treatment of diabetes, allowing patients with DM1 to have more flexible food choices. This study aimed to evaluate the influence of nutrition intervention and the use of multiple short-acting insulin according to the carbohydrate counting method on clinical and metabolic control in patients with DM1. Methods Our sample consisted of 51 patients with DM1, 32 females, aged 25.3 ± 1.55 years. A protocol of nutritional status evaluation was applied and laboratory analysis was performed at baseline and after a three-month intervention. After the analysis of the food records, a balanced diet was prescribed using the carbohydrate counting method, and short-acting insulin was prescribed based on the total amount of carbohydrate per meal (1 unit per 15 g of carbohydrate. Results A significant decrease in A1c levels was observed from baseline to the three-month evaluation after the intervention (10.40 ± 0.33% and 9.52 ± 0.32%, respectively, p = 0.000. It was observed an increase in daily insulin dose after the intervention (0.99 ± 0.65 IU/Kg and 1.05 ± 0.05 IU/Kg, respectively, p = 0.003. No significant differences were found regarding anthropometric evaluation (BMI, waist, hip or abdominal circumferences and waist to hip ratio after the intervention period. Conclusions The use of short-acting insulin based on the carbohydrate counting method after a short period of time resulted in a significant improvement of the glycemic control in patients with DM1 with no changes in body weight despite increases in the total daily insulin doses.

{sup 90}Y -PET imaging: Exploring limitations and accuracy under conditions of low counts and high random fraction

Energy Technology Data Exchange (ETDEWEB)

Carlier, Thomas, E-mail: thomas.carlier@chu-nantes.fr [Department of Nuclear Medicine, University Hospital of Nantes, Place Alexis Ricordeau, Nantes 44093, France and CRCNA–UMR 892 INSERM 6299 CNRS, 8 quai Moncousu BP 70721, Nantes 44007 (France); Willowson, Kathy P. [Institute of Medical Physics, University of Sydney, Camperdown, New South Wales 2006 (Australia); Fourkal, Eugene [Department of Radiation Oncology, Allegheny General Hospital, Pittsburgh, Pennsylvania 15212 (United States); Bailey, Dale L. [Faculty of Health Sciences, University of Sydney, Lidcombe 2141, Australia and Department of Nuclear Medicine, Royal North Shore Hospital, St Leonards, New South Wales 2065 (Australia); Doss, Mohan [Department of Diagnostic Imaging, Fox Chase Cancer Center, Philadelphia, Pennsylvania 19111 (United States); Conti, Maurizio [Siemens Healthcare Molecular Imaging, 810 Innovation Drive, Knoxville, Tennessee 37932 (United States)

2015-07-15

Purpose: {sup 90}Y -positron emission tomography (PET) imaging is becoming a recognized modality for postinfusion quantitative assessment following radioembolization therapy. However, the extremely low counts and high random fraction associated with {sup 90}Y -PET may significantly impair both qualitative and quantitative results. The aim of this work was to study image quality and noise level in relation to the quantification and bias performance of two types of Siemens PET scanners when imaging {sup 90}Y and to compare experimental results with clinical data from two types of commercially available {sup 90}Y microspheres. Methods: Data were acquired on both Siemens Biograph TruePoint [non-time-of-flight (TOF)] and Biograph microcomputed tomography (mCT) (TOF) PET/CT scanners. The study was conducted in three phases. The first aimed to assess quantification and bias for different reconstruction methods according to random fraction and number of true counts in the scan. The NEMA 1994 PET phantom was filled with water with one cylindrical insert left empty (air) and the other filled with a solution of {sup 90}Y . The phantom was scanned for 60 min in the PET/CT scanner every one or two days. The second phase used the NEMA 2001 PET phantom to derive noise and image quality metrics. The spheres and the background were filled with a {sup 90}Y solution in an 8:1 contrast ratio and four 30 min acquisitions were performed over a one week period. Finally, 32 patient data (8 treated with Therasphere{sup ®} and 24 with SIR-Spheres{sup ®}) were retrospectively reconstructed and activity in the whole field of view and the liver was compared to theoretical injected activity. Results: The contribution of both bremsstrahlung and LSO trues was found to be negligible, allowing data to be decay corrected to obtain correct quantification. In general, the recovered activity for all reconstruction methods was stable over the range studied, with a small bias appearing at extremely

Enhanced low-level LSC performance for carbon-14 dating using a bismuth germanate (Bi4Ge3O12) quasi-active guard

International Nuclear Information System (INIS)

Cook, G.T.

1995-01-01

The Packard 2770TR/SL is a novel low-level liquid scintillation spectrometer which employs bismuth germanate (BGO - Bi 4 Ge 3 O 12 ) as a quasi-active guard to reduce background count rates and improve limits of detection. The results of this study indicate that this system shows tremendous potential for radiocarbon dating. Its great advantage is that it can give exceptional performance using standard low 40 K borosilicate glass vials costing only a few cents each. For example, in an optimized counting window, 4.6-mL 14 C benzene contained in a standard 7-mL glass vial produced a background count rate of 0.49 cpm and an efficiency of 70.3%, yielding a figure of merit (E 2 V 2 /B) value of 213,000 ±9,000 (where B = background count rate in counts per minute [cpm], E = percentage efficiency, and V = volume of benzene). This performance is comparable to published data for low-level instruments which employ active coincidence guard detectors and standard glass vials. When the same vials were recounted in vial holders, specially fabricated from BGO, the corresponding optimum values for background, efficiency and figure of merit, respectively, were 0.24 cpm, 61.0% and 328,000 ± 19,000. This performance is comparable to that of other low-level counting instruments when they are used in combination with specialized Teflon and silica vials. The BGO vial holders were also used in previous generations of Packard instruments which employ time resolved liquid scintillation counting (TR-LSC) for electronic background reduction and this resulted in significant improvements in performance

Ophthalmic manifestations of 107 cases with hemolysis, elevated liver enzymes and low platelet count syndrome

International Nuclear Information System (INIS)

Erbagci, I.; Okumus, S.; Bekir, Necdet A.; Karaca, M.; Ugur, Mete G.

2008-01-01

Objective was to present various ophthalmologic disorders in a clinical series of hemolysis, elevated liver enzymes and low platelet count (HELLP) syndrome cases. This is a prospective clinical study performed between 2002 and 2005. One hundred seven HELLP attended in either Departments of Ophthalmology or Obstetrics and Gynecology, Medical School, Gaziantep University, Gaziantep, Turkey were evaluated. Mean age was 25.5 (22-36 years). Mean levels were 2.5 gravidity, 1.3 parity, 55,200/mm3 platelet counts, 308.7 U/I aspartate transaminase, 255.4 U/I alanine transminase and 1711.6U/I lactate dehydrogenase. Four patients died (3.7%) despite the proper treatments. Cortical blindness was observed in 3 cases (2.7%), serous retinal detachments in 4 (3.7%) and mild hypertension changes in 18 (16%). Ophthalmic complications are possible during and after this syndrome. Almost all ophthalmologic changes recover after delivery by cesarean section, nevertheless, it is essential that ophthalmologists should be aware of retinal disorders when this fatal complication of pregnancy is encountered. (author)

Recommended methods for monitoring change in bird populations by counting and capture of migrants

Science.gov (United States)

David J. T. Hussell; C. John Ralph

2005-01-01

Counts and banding captures of spring or fall migrants can generate useful information on the status and trends of the source populations. To do so, the counts and captures must be taken and recorded in a standardized and consistent manner. We present recommendations for field methods for counting and capturing migrants at intensively operated sites, such as bird...

Ballistic deficit correction methods for large Ge detectors-high counting rate study

International Nuclear Information System (INIS)

Duchene, G.; Moszynski, M.

1995-01-01

This study presents different ballistic correction methods versus input count rate (from 3 to 50 kcounts/s) using four large Ge detectors of about 70 % relative efficiency. It turns out that the Tennelec TC245 linear amplifier in the BDC mode (Hinshaw method) is the best compromise for energy resolution throughout. All correction methods lead to narrow sum-peaks indistinguishable from single Γ lines. The full energy peak throughput is found representative of the pile-up inspection dead time of the corrector circuits. This work also presents a new and simple representation, plotting simultaneously energy resolution and throughput versus input count rate. (TEC). 12 refs., 11 figs

Material screening with HPGe counting station for PandaX experiment

International Nuclear Information System (INIS)

Wang, X.; Chen, X.; Fu, C.; Ji, X.; Liu, X.; Xie, P.; Zhang, T.; Mao, Y.; Wang, S.; Wang, H.

2016-01-01

A gamma counting station based on high-purity germanium (HPGe) detector was set up for the material screening of the PandaX dark matter experiments in the China Jinping Underground Laboratory. Low background gamma rate of 2.6 counts/min within the energy range of 20 to 2700 keV is achieved due to the well-designed passive shield. The sentivities of the HPGe detetector reach mBq/kg level for isotopes like K, U, Th, and even better for Co and Cs, resulted from the low-background rate and the high relative detection efficiency of 175%. The structure and performance of the counting station are described in this article. Detailed counting results for the radioactivity in materials used by the PandaX dark-matter experiment are presented. The upgrading plan of the counting station is also discussed.

Determination of 90Sr in low-level radioactive wastes using extraction chromatography and LSC

International Nuclear Information System (INIS)

Temba, Eliane S.C.; Reis Junior, Aluisio S.; Mingote, Raquel M.; Monteiro, Roberto P.G.

2009-01-01

A procedure for the determination of 90 Sr in low-level radioactive wastes is presented in this work. It is a part of a methodology developed for the sequential radiochemical separation of radionuclides in low-level radioactive wastes. These radionuclides comprises the actinides and 55 Fe, 63 Ni and 90 Sr, classified as difficult-to-measure (DTM) radionuclides in the radioactive waste characterization, because they cannot be measured by direct measurements, like gamma spectrometry. A variety of methods have been reported in the literature, based on precipitation, liquid-liquid extraction and ion exchange. In this work, the separation was carried out using precipitation and extraction chromatography using the Sr Resin (Eichrom). This resin is strontium-selective, the extractant is a crown ether-derivative immobilized on an inert polymeric support. The 90 Sr eluted from column was measured by LSC. The counting was carried out within 5 hours of the start of yttrium ingrowth to minimize interferences from 90 Y. The counting efficiency was calculated by using a 90 Sr standard solution purified by the specific resin. The chemical yield of the procedure was determined gravimetrically by the addition of a stable Sr carrier. Optimum conditions for the pretreatment, separation and LSC setting were determined using simulated samples. This procedure showed to be rapid and achieved a good chemical recovery, with an average of 84 %, and a detection limit of 0.6 Bq L -1 . (author)

Binomial distribution of Poisson statistics and tracks overlapping probability to estimate total tracks count with low uncertainty

International Nuclear Information System (INIS)

Khayat, Omid; Afarideh, Hossein; Mohammadnia, Meisam

2015-01-01

In the solid state nuclear track detectors of chemically etched type, nuclear tracks with center-to-center neighborhood of distance shorter than two times the radius of tracks will emerge as overlapping tracks. Track overlapping in this type of detectors causes tracks count losses and it becomes rather severe in high track densities. Therefore, tracks counting in this condition should include a correction factor for count losses of different tracks overlapping orders since a number of overlapping tracks may be counted as one track. Another aspect of the problem is the cases where imaging the whole area of the detector and counting all tracks are not possible. In these conditions a statistical generalization method is desired to be applicable in counting a segmented area of the detector and the results can be generalized to the whole surface of the detector. Also there is a challenge in counting the tracks in densely overlapped tracks because not sufficient geometrical or contextual information are available. It this paper we present a statistical counting method which gives the user a relation between the tracks overlapping probabilities on a segmented area of the detector surface and the total number of tracks. To apply the proposed method one can estimate the total number of tracks on a solid state detector of arbitrary shape and dimensions by approximating the tracks averaged area, whole detector surface area and some orders of tracks overlapping probabilities. It will be shown that this method is applicable in high and ultra high density tracks images and the count loss error can be enervated using a statistical generalization approach. - Highlights: • A correction factor for count losses of different tracks overlapping orders. • For the cases imaging the whole area of the detector is not possible. • Presenting a statistical generalization method for segmented areas. • Giving a relation between the tracks overlapping probabilities and the total tracks

Change-Point Methods for Overdispersed Count Data

National Research Council Canada - National Science Library

Wilken, Brian A

2007-01-01

.... Although the Poisson model is often used to model count data, the two-parameter gamma-Poisson mixture parameterization of the negative binomial distribution is often a more adequate model for overdispersed count data...

A flowrate measurement method by counting of radioactive particles suspended in a liquid

International Nuclear Information System (INIS)

Daniel, G.

1983-04-01

By external counting of fine #betta# emitting radioactive particles suspended in a liquid, the flowrate in a system of pipes can be measured. The study comprises three phases: 1. - The hydraulic validity of the method is demonstrated in laminar as well as in turbulent flow under certain conditions of particles size and density and of liquid viscosity. 2. - Radioactive labelling of microspheres of serumalbumin or ion exchange resins with indium 113m delivered by a generator Tin 113 → Indium 113m. 3. - Counting with a scintillation detector: a method of threshold overstepping is experimented with a mechanical or electronic simulator; the statistical study of particle superposition under the detector enables a correction for the resulting counting losses to be proposed. The method provides absolute measurements, but is particularly suitable to measure relative flowrates in a hydraulic network. It can be continuous and does not perturb the flow and the network. The accuracy of the method is analysed in details [fr

Coherence modulation at the photon-counting level: A new scheme for secure communication

International Nuclear Information System (INIS)

Rhodes, William T; Boughanmi, Abdellatif; Moreno, Yezid Torres

2016-01-01

When operated at the photon-counting level, coherence modulation can provide quantifiably secure binary signal transmission between two entities, security being based on the nonclonability of photons. (paper)

A statistical analysis of count normalization methods used in positron-emission tomography

International Nuclear Information System (INIS)

Holmes, T.J.; Ficke, D.C.; Snyder, D.L.

1984-01-01

As part of the Positron-Emission Tomography (PET) reconstruction process, annihilation counts are normalized for photon absorption, detector efficiency and detector-pair duty-cycle. Several normalization methods of time-of-flight and conventional systems are analyzed mathematically for count bias and variance. The results of the study have some implications on hardware and software complexity and on image noise and distortion

Preparation of 'dead water' for low background liquid scintillation counting

International Nuclear Information System (INIS)

Morishima, Hiroshige; Koga, Taeko; Niwa, Takeo; Kawai, Hiroshi

1987-01-01

'Dead water', low level tritiated water is indispensable to measure tritium concentration in environmental waters using a low background liquid scintillation counter. Water produced by combustion of natural gas, or deep sea water etc. are usually used for the above purpose. A new method of reducing tritium concentration in natural water has been introduced for preparation of 'dead water'. This method is to combine hydrogen-oxygen mixture produced by water electrolysis with hopcalite catalyzer at 700 deg C. Deep well water was electrolized up to 2/3 volume, and tritium concentration of recombined water was reduced to be about one third of that of the original one. (author)

Simple analytical technique for liquid scintillation counting of environmental carbon-14 using gel suspension method

International Nuclear Information System (INIS)

Okai, Tomio; Wakabayashi, Genichiro; Nagao, Kenjiro; Matoba, Masaru; Ohura, Hirotaka; Momoshima, Noriyuki; Kawamura, Hidehisa

2000-01-01

A simple analytical technique for liquid scintillation counting of environmental 14 C was developed. Commercially available gelling agent, N-lauroyl-L -glutamic -α,γ-dibutylamide, was used for the gel-formation of the samples (gel suspension method) and for the subsequent liquid scintillation counting of 14 C in the form of CaCO 3 . Our procedure for sample preparation is much simpler than that of the conventional methods and requires no special equipment. Self absorption, stability and reproducibility of gel suspension samples were investigated in order to evaluate the characteristics of the gel suspension method for 14 C activity measurement. The self absorption factor is about 70% and slightly decrease as CaCO 3 weight increase. This is considered to be mainly due to the absorption of β-rays and scintillation light by the CaCO 3 sample itself. No change of the counting rate for the gel suspension sample was observed for more than 2 years after the sample preparation. Four samples were used for checking the reproducibility of the sample preparation method. The same values were obtained for the counting rate of 24 C activity within the counting error. No change of the counting rate was observed for the 're-gelated' sample. These results show that the gel suspension method is appropriate for the 14 C activity measurement by the liquid scintillation counting method and useful for a long-term preservation of the sample for repeated measurement. The above analytical technique was applied to actual environmental samples in Fukuoka prefecture, Japan. Results obtained were comparable with those by other researchers and appear to be reasonable. Therefore, the newly developed technique is useful for the routine monitoring of environmental 14 C. (author)

Partial-Interval Estimation of Count: Uncorrected and Poisson-Corrected Error Levels

Science.gov (United States)

Yoder, Paul J.; Ledford, Jennifer R.; Harbison, Amy L.; Tapp, Jon T.

2018-01-01

A simulation study that used 3,000 computer-generated event streams with known behavior rates, interval durations, and session durations was conducted to test whether the main and interaction effects of true rate and interval duration affect the error level of uncorrected and Poisson-transformed (i.e., "corrected") count as estimated by…

The determination of the optimum counting conditions for a ZnS(Ag) scintillation detector

International Nuclear Information System (INIS)

Djurasevic, M.M.; Kandic, A.B.; Novkovic, D.N; Vukanac, I.S. . E-mail address of corresponding author: mirad@vin.bg.ac.yu; Djurasevic, M.M.)

2005-01-01

The methods that use scintillation counting with ZnS(Ag) scintillation detector are widely used for gross alpha activity determination. The common criteria for the selection of optimum counting condition for a ZnS(Ag) scintillation detector do not consider simultaneously operating voltage and discrimination level variation. In presented method a relationship between voltage and discrimination level is derived for counting efficiency. (author)

An improved method for chromosome counting in maize.

Science.gov (United States)

Kato, A

1997-09-01

An improved method for counting chromosomes in maize (Zea mays L.) is presented. Application of cold treatment (5C, 24 hr), heat treatment (42 C, 5 min) and a second cold treatment (5C, 24 hr) to root tips before fixation increased the number of condensed and dispersed countable metaphase chromosome figures. Fixed root tips were prepared by the enzymatic maceration-air drying method and preparations were stained with acetic orcein. Under favorable conditions, one preparation with 50-100 countable chromosome figures could be obtained in diploid maize using this method. Conditions affecting the dispersion of the chromosomes are described. This technique is especially useful for determining the somatic chromosome number in triploid and tetraploid maize lines.

Analytical method of Kr-85 determination, using cryogenic concentration and separation and liquid scintillation counting

International Nuclear Information System (INIS)

Heras Iniquez, M.C.; Perez Garcia, M.M.; Grau Malonda, A.

1983-01-01

The method used in the Laboratory of the JEN for the determination of Kr-85 levels in gaseous effluents of nuclear power and in the atmosphere is described. Samples of air, collected in metallic cylinders, are introduced into a gas-solid chromatographic separation system which resolves Kr from the other air components. The separated Kr ia dissolved in a toluene based scintillation cocktail, and the Kr-85 content is determined by liquid scintillation counting. (Author)

Using observation-level random effects to model overdispersion in count data in ecology and evolution

Directory of Open Access Journals (Sweden)

Xavier A. Harrison

2014-10-01

Full Text Available Overdispersion is common in models of count data in ecology and evolutionary biology, and can occur due to missing covariates, non-independent (aggregated data, or an excess frequency of zeroes (zero-inflation. Accounting for overdispersion in such models is vital, as failing to do so can lead to biased parameter estimates, and false conclusions regarding hypotheses of interest. Observation-level random effects (OLRE, where each data point receives a unique level of a random effect that models the extra-Poisson variation present in the data, are commonly employed to cope with overdispersion in count data. However studies investigating the efficacy of observation-level random effects as a means to deal with overdispersion are scarce. Here I use simulations to show that in cases where overdispersion is caused by random extra-Poisson noise, or aggregation in the count data, observation-level random effects yield more accurate parameter estimates compared to when overdispersion is simply ignored. Conversely, OLRE fail to reduce bias in zero-inflated data, and in some cases increase bias at high levels of overdispersion. There was a positive relationship between the magnitude of overdispersion and the degree of bias in parameter estimates. Critically, the simulations reveal that failing to account for overdispersion in mixed models can erroneously inflate measures of explained variance (r2, which may lead to researchers overestimating the predictive power of variables of interest. This work suggests use of observation-level random effects provides a simple and robust means to account for overdispersion in count data, but also that their ability to minimise bias is not uniform across all types of overdispersion and must be applied judiciously.

Low-level-waste-treatment handbook

International Nuclear Information System (INIS)

Clinton, S.D.; Goeller, H.E.; Holladay, D.W.; Donaldson, T.L.

1982-01-01

The initial draft of the Low-Level Waste Treatment Handbook has been prepared and submitted to the DOE Low-Level Waste Management Program for review and comment. A revised draft is scheduled to be delivered to DOE Headquarters in December 1982. The Handbook is designed to be useful to all individuals and groups concerned with low-level wastes. It is one of several volumes that will ultimately comprise a Low-Level Waste Technology Handbook. The objective of the Low-Level Waste Treatment Handbook is to present an overview of current practices related to the segregation, classification, volume reduction, solidification, handling, packaging, and transportation of LLW for disposal in a shallow land burial facility. The Handbook is intended to serve as a guide to individuals interested in the treatment and handling of low-level radioactive waste. The Handbook will not explicitly tell the user how to design and operate LLW treatment facilities, but rather will identify (1) kinds of information required to evaluate the options, (2) methods that may be used to evaluate these options, and (3) limitations associated with the selection of the treatment options. The focus of the Handbook is providing guidance on how to do waste treatment for disposal by shallow land burial

Technical feasibility proof for high-resolution low-dose photon-counting CT of the breast

Energy Technology Data Exchange (ETDEWEB)

Kalender, Willi A.; Kolditz, Daniel; Lueck, Ferdinand [University of Erlangen-Nuernberg, Institute of Medical Physics (IMP), Erlangen (Germany); CT Imaging GmbH, Erlangen (Germany); Steiding, Christian [University of Erlangen-Nuernberg, Institute of Medical Physics (IMP), Erlangen (Germany); CT Imaging GmbH, Erlangen (Germany); University Hospital of Erlangen, Institute of Radiology, Erlangen (Germany); Ruth, Veikko; Roessler, Ann-Christin [University of Erlangen-Nuernberg, Institute of Medical Physics (IMP), Erlangen (Germany); Wenkel, Evelyn [University Hospital of Erlangen, Institute of Radiology, Erlangen (Germany)

2017-03-15

X-ray computed tomography (CT) has been proposed and evaluated multiple times as a potentially alternative method for breast imaging. All efforts shown so far have been criticized and partly disapproved because of their limited spatial resolution and higher patient dose when compared to mammography. Our concept for a dedicated breast CT (BCT) scanner therefore aimed at novel apparatus and detector design to provide high spatial resolution of about 100 μm and average glandular dose (AGD) levels of 5 mGy or below. Photon-counting technology was considered as a solution to reach these goals. The complete concept was previously evaluated and confirmed by simulations and basic experiments on laboratory setups. We here present measurements of dose, technical image quality parameters and surgical specimen results on such a scanner. For comparison purposes, the specimens were also imaged with digital mammography (DM) and breast tomosynthesis (BT) apparatus. Results show that photon-counting BCT (pcBCT) at 5 mGy AGD offers sufficiently high 3D spatial resolution for reliable detectability of calcifications and soft tissue delineation. (orig.)

A Lossy Counting-Based State of Charge Estimation Method and Its Application to Electric Vehicles

Directory of Open Access Journals (Sweden)

Hong Zhang

2015-12-01

Full Text Available Estimating the residual capacity or state-of-charge (SoC of commercial batteries on-line without destroying them or interrupting the power supply, is quite a challenging task for electric vehicle (EV designers. Many Coulomb counting-based methods have been used to calculate the remaining capacity in EV batteries or other portable devices. The main disadvantages of these methods are the cumulative error and the time-varying Coulombic efficiency, which are greatly influenced by the operating state (SoC, temperature and current. To deal with this problem, we propose a lossy counting-based Coulomb counting method for estimating the available capacity or SoC. The initial capacity of the tested battery is obtained from the open circuit voltage (OCV. The charging/discharging efficiencies, used for compensating the Coulombic losses, are calculated by the lossy counting-based method. The measurement drift, resulting from the current sensor, is amended with the distorted Coulombic efficiency matrix. Simulations and experimental results show that the proposed method is both effective and convenient.

Clinical significance of determination of changes of serum TNF-α levels, peripheral B lymphocyte count and T lymphocyte subsets distribution pattern in patients with pregnancy induced hypertension syndrome

International Nuclear Information System (INIS)

Zhao Wenjuan

2006-01-01

Objective: To explore the changes of serum TNF-α levels, peripheral B cell count and T subsets distribution pattern in patients with pregnancy induced hypertension syndrome. Methods: Serum TNF-α levels (with RIA), peripheral B cell count as well as T subsets (with monoclonal technique) were examined in 34 patients with pregnancy induced hypertension syndrome and 35 controls. Results: The serum TNF-α levels and B lymphocytes count were significantly higher than those in controls (P 3 , CD 4 , CD4/CD8 ratio were significantly lower than those in controls (P<0.01). Conclusion: Pregnancy induced hY- pertension syndrome is a kind of autoimmune diseases with abnormal immunoregulation. (authors)

Investigation of ultra low-dose scans in the context of quantum-counting clinical CT

Science.gov (United States)

Weidinger, T.; Buzug, T. M.; Flohr, T.; Fung, G. S. K.; Kappler, S.; Stierstorfer, K.; Tsui, B. M. W.

2012-03-01

In clinical computed tomography (CT), images from patient examinations taken with conventional scanners exhibit noise characteristics governed by electronics noise, when scanning strongly attenuating obese patients or with an ultra-low X-ray dose. Unlike CT systems based on energy integrating detectors, a system with a quantum counting detector does not suffer from this drawback. Instead, the noise from the electronics mainly affects the spectral resolution of these detectors. Therefore, it does not contribute to the image noise in spectrally non-resolved CT images. This promises improved image quality due to image noise reduction in scans obtained from clinical CT examinations with lowest X-ray tube currents or obese patients. To quantify the benefits of quantum counting detectors in clinical CT we have carried out an extensive simulation study of the complete scanning and reconstruction process for both kinds of detectors. The simulation chain encompasses modeling of the X-ray source, beam attenuation in the patient, and calculation of the detector response. Moreover, in each case the subsequent image preprocessing and reconstruction is modeled as well. The simulation-based, theoretical evaluation is validated by experiments with a novel prototype quantum counting system and a Siemens Definition Flash scanner with a conventional energy integrating CT detector. We demonstrate and quantify the improvement from image noise reduction achievable with quantum counting techniques in CT examinations with ultra-low X-ray dose and strong attenuation.

Low level liquid scintillation analysis for environmental and biomedical quantitation

International Nuclear Information System (INIS)

Kessler, M.J.

1991-01-01

Over the past five years low level liquid scintillation counting has become increasing popular because of the large number of applications which can be performed using this technique. These applications include environmental monitoring ( 3 H, 90 Sr/ 90 Y, etc.), radiocarbon dating (for age determination to 50,000 years), food adulteration studies (alcohol and beverage industries), radon monitoring (air/water), nuclear power plant monitoring (low level 3 H) and metabolism studies (pharmaceutical research). These applications can be performed with either a dedicated low level LSC or using a standard liquid scintillation counter in conjunction with the new technique of time-resolved LSC (TR-LSC). This technique when used on a standard LSC reduces the instrument background without substantially effecting the background, thus increasing the performance (E 2 /B) of the LSC. Data will be presented for each of the applications mentioned above, comparing the standard LSC and the new TR-LSC techniques. The optimization of the samples for each of these applications will be explored in detail with experimental results. In conclusion, by using the TR-LSC technique in conjunction with a standard LSC the performance of the standard LSC can be increased substantially without dedicating the LSC to doing only low level samples

Understanding low-level radioactive waste. National Low-Level Radioactive Waste Management Program

International Nuclear Information System (INIS)

1983-10-01

Chapters are devoted to: background and policymaking for low-level waste management; commercial low-level waste generation; Department of Energy low-level waste generation; low-level waste treatment; packaging and transportation; commercial low-level waste disposal; Department of Energy low-level waste disposal; Department of Energy low-level waste management program; and laws and regulations

Controversy among giants: Young's experiment and loss of fringe visibility at low photon-count levels

Science.gov (United States)

Rhodes, William T.

2011-09-01

An ideal beam splitter model for an absorber presented by Leonhardt in his book Measuring the Quantum State of Light (Cambridge University Press, 1997) has intriguing implications for the simple Young's fringe experiment in the photon-counting regime. Specifically, it suggests that different results will be obtained depending on whether the light forming the fringes is attenuated at the source or at the slits.

High levels of T lymphocyte activation in Leishmania-HIV-1 co-infected individuals despite low HIV viral load

Directory of Open Access Journals (Sweden)

Grinsztejn Beatriz

2010-12-01

Full Text Available Abstract Background Concomitant infections may influence HIV progression by causing chronic activation leading to decline in T-cell function. In the Americas, visceral (AVL and tegumentary leishmaniasis (ATL have emerged as important opportunistic infections in HIV-AIDS patients and both of those diseases have been implicated as potentially important co-factors in disease progression. We investigated whether leishmaniasis increases lymphocyte activation in HIV-1 co-infected patients. This might contribute to impaired cellular immune function. Methods To address this issue we analyzed CD4+ T absolute counts and the proportion of CD8+ T cells expressing CD38 in Leishmania/HIV co-infected patients that recovered after anti-leishmanial therapy. Results We found that, despite clinical remission of leishmaniasis, AVL co-infected patients presented a more severe immunossupression as suggested by CD4+ T cell counts under 200 cells/mm3, differing from ATL/HIV-AIDS cases that tends to show higher lymphocytes levels (over 350 cells/mm3. Furthermore, five out of nine, AVL/HIV-AIDS presented low CD4+ T cell counts in spite of low or undetectable viral load. Expression of CD38 on CD8+ T lymphocytes was significantly higher in AVL or ATL/HIV-AIDS cases compared to HIV/AIDS patients without leishmaniasis or healthy subjects. Conclusions Leishmania infection can increase the degree of immune system activation in individuals concomitantly infected with HIV. In addition, AVL/HIV-AIDS patients can present low CD4+ T cell counts and higher proportion of activated T lymphocytes even when HIV viral load is suppressed under HAART. This fact can cause a misinterpretation of these laboratorial markers in co-infected patients.

Big drop. [Decline in sperm counts from environmental pollution

Energy Technology Data Exchange (ETDEWEB)

Castleman, M.

Statisticians at the University of Copenhagen have published a review of sperm-count studies carried out from 1938-1990. After controlling for such things as counting techniques and sexual activity, they found that average sperm counts have decreased 42% over the last 50 years. After eliminating possible causes such as heat and differences in counting techniques, the only plausible cause left was environmental pollution. This finding correlates with a study performed in 1979 which found abnormally high concentrations of such toxic pollutants as DDT and PCBs in semen. The Copenhagen study suggests that even at low levels of exposure, environmental pollution is having biological consequences.

Determination of 222Rn in water samples from wells and springs in Tokyo by a modified integral counting method

International Nuclear Information System (INIS)

Homma, Y.; Murase, Y.; Handa, K.; Murakami, I.

1997-01-01

222 Rn in 2L-water samples was extracted with 30 mL toluene, and 21 mL of the toluene solution was transferred into a liquid scintillation vial, in which PPO - 2,5-diphenyloxazole was placed in advance. The total activity of 222 Rn in the water sample was calculated based on the Ostwald's coefficient of solubilities of 222 Rn in toluene and water at the temperature of the sample water and the volume of water and toluene. About 40% of 222 Rn dissolved in 2L-water sample can be collected. After allowing to stand for 3.5 h, the equilibrium mixture of 222 Rn and its daughters was measured with an Aloka liquid scintillation spectrometer using a modified integral counting method which extrapolates the integral counting curve not to the zero pulse-height, but to the zero detection threshold, an average energy required to produce a measurable pulse, of the liquid scintillation spectrometer. The general method which agitates water sample (usually about 10 mL) with a liquid scintillation cocktail is practical when the activity of 222 Rn is high. By adding 10 mL of water sample, however, it is possible also to add variable amounts of quencher. In some cases water sample is preserved with nitric acid. The slope of the integral counting rate curve increases as quench level of the sample increases. Therefore, it is clear that the modified integral counting method gives more accurate 222 Rn concentrations for water samples of strong quench than the conventional integral counting method. 222 Rn sample of 0.2 Bq/L can be determined within an overall uncertainty of 3.1%

A sub-boiling distillation method for the preparation of low carbon content water from urine samples for tritium measurement by liquid scintillation counting

International Nuclear Information System (INIS)

Nogawa, Norio; Makide, Yoshihiro

1999-01-01

A new preparation method was developed for obtaining low carbon content water from urine samples for the measurement of tritium by a liquid scintillation counter. The method uses a simple and convenient subboiling distillation bottle. Many urine samples have been purified by this method and the change of tritium level in a tritium-handling radiation-worker was observed

Q2 - a very low level quantitative and qualitative waste assay and release certification system

International Nuclear Information System (INIS)

Bronson, F.L.

1990-01-01

Low level radioactive waste disposal is very expensive, especially when all of the handling transportation and documentation costs are included. However for most generators, a large fraction of this low level waste is not contaminated at all, or only slightly so. The paper describes the development and performance of a low level counter that is convenient to use, and that can accurately identify and quantify the radioactivity of any gamma emitter thing that can be placed in a 55 gallon (200 liter) container. These measurement results can be used to verify the absence of radioactivity at a very low levels (10 nCi (370 Bq)/sample), and to identify the nuclides and quantities present, while differentiating against natural radioactivity (Radium, Thorium, Potassium). These results can be used as part of a 10CFR20.302 waste stream exemption program, and thus allow significant savings and a less than 1 year payback at a typical nuclear power plant. The Q1 system is fully shielded to allow it's use in the low level radwaste storage area. The detectors are either 3 Intrinsic Germanium detectors or 2 large NaI detectors. The software is fully automated for simple operation. Correlation factors can be entered to estimate non-gamma emitters from pre-established correlations to other nuclides. Typical Ge detector sensitivities are 8 nCi (300 Bq) LLD for Cs-137 at 0.8 g/cc for a 10 minute count time. NaI detector systems can achieve the same LLD in a 1 minute count. 5 figs., 1 tab

CD68+ cell count, early evaluation with PET and plasma TARC levels predict response in Hodgkin lymphoma.

Science.gov (United States)

Cuccaro, Annarosa; Annunziata, Salvatore; Cupelli, Elisa; Martini, Maurizio; Calcagni, Maria L; Rufini, Vittoria; Giachelia, Manuela; Bartolomei, Francesca; Galli, Eugenio; D'Alò, Francesco; Voso, Maria T; Leone, Giuseppe; Giordano, Alessandro; Larocca, Luigi M; Hohaus, Stefan

2016-03-01

Early response evaluation with [(18) F]fluordeoxyglucose (FDG) positron emission tomography after 2 cycles of chemotherapy (interim PET) has been indicated as the strongest predictor for outcome in classical Hodgkin lymphoma (HL). We studied the prognostic role of the number of tumor-infiltrating CD68+ cells and of the plasma levels of TARC (thymus and activation-regulated chemokine) in the context of interim PET in 102 patients with classical HL treated with Adriamycin, Bleomycin, Vinblastine, Dacarbazine (ABVD). After 2 ABVD cycles, interim PET according to Deauville criteria was negative (score 0-3) in 85 patients and positive (score 4-5) in 15 patients (2 patients technically not evaluable). TARC levels were elevated in 89% of patients at diagnosis, and decreased after 2 cycles in 82% of patients. Persistently elevated TARC levels in 18% of patients were significantly associated with a positive PET result (P = 0.007). Strong predictors for progression-free survival (PFS) were a negative interim PET (85% vs. 28%, P evaluation had no prognostic role. In multivariate analysis, interim PET, CD68+ cell counts and presence of B-symptoms were independently associated with PFS. We conclude that although TARC levels are a biomarker for early response evaluation, they cannot substitute for interim PET as outcome predictor in HL. The evaluation of CD68 counts and B-symptoms at diagnosis may help to identify low-risk patients regardless positive interim PET. © 2016 The Authors. Cancer Medicine published by John Wiley & Sons Ltd.

Automated vehicle counting using image processing and machine learning

Science.gov (United States)

Meany, Sean; Eskew, Edward; Martinez-Castro, Rosana; Jang, Shinae

2017-04-01

Vehicle counting is used by the government to improve roadways and the flow of traffic, and by private businesses for purposes such as determining the value of locating a new store in an area. A vehicle count can be performed manually or automatically. Manual counting requires an individual to be on-site and tally the traffic electronically or by hand. However, this can lead to miscounts due to factors such as human error A common form of automatic counting involves pneumatic tubes, but pneumatic tubes disrupt traffic during installation and removal, and can be damaged by passing vehicles. Vehicle counting can also be performed via the use of a camera at the count site recording video of the traffic, with counting being performed manually post-recording or using automatic algorithms. This paper presents a low-cost procedure to perform automatic vehicle counting using remote video cameras with an automatic counting algorithm. The procedure would utilize a Raspberry Pi micro-computer to detect when a car is in a lane, and generate an accurate count of vehicle movements. The method utilized in this paper would use background subtraction to process the images and a machine learning algorithm to provide the count. This method avoids fatigue issues that are encountered in manual video counting and prevents the disruption of roadways that occurs when installing pneumatic tubes

Discrete calculus methods for counting

CERN Document Server

Mariconda, Carlo

2016-01-01

This book provides an introduction to combinatorics, finite calculus, formal series, recurrences, and approximations of sums. Readers will find not only coverage of the basic elements of the subjects but also deep insights into a range of less common topics rarely considered within a single book, such as counting with occupancy constraints, a clear distinction between algebraic and analytical properties of formal power series, an introduction to discrete dynamical systems with a thorough description of Sarkovskii’s theorem, symbolic calculus, and a complete description of the Euler-Maclaurin formulas and their applications. Although several books touch on one or more of these aspects, precious few cover all of them. The authors, both pure mathematicians, have attempted to develop methods that will allow the student to formulate a given problem in a precise mathematical framework. The aim is to equip readers with a sound strategy for classifying and solving problems by pursuing a mathematically rigorous yet ...

Design of time interval generator based on hybrid counting method

International Nuclear Information System (INIS)

Yao, Yuan; Wang, Zhaoqi; Lu, Houbing; Chen, Lian; Jin, Ge

2016-01-01

Time Interval Generators (TIGs) are frequently used for the characterizations or timing operations of instruments in particle physics experiments. Though some “off-the-shelf” TIGs can be employed, the necessity of a custom test system or control system makes the TIGs, being implemented in a programmable device desirable. Nowadays, the feasibility of using Field Programmable Gate Arrays (FPGAs) to implement particle physics instrumentation has been validated in the design of Time-to-Digital Converters (TDCs) for precise time measurement. The FPGA-TDC technique is based on the architectures of Tapped Delay Line (TDL), whose delay cells are down to few tens of picosecond. In this case, FPGA-based TIGs with high delay step are preferable allowing the implementation of customized particle physics instrumentations and other utilities on the same FPGA device. A hybrid counting method for designing TIGs with both high resolution and wide range is presented in this paper. The combination of two different counting methods realizing an integratable TIG is described in detail. A specially designed multiplexer for tap selection is emphatically introduced. The special structure of the multiplexer is devised for minimizing the different additional delays caused by the unpredictable routings from different taps to the output. A Kintex-7 FPGA is used for the hybrid counting-based implementation of a TIG, providing a resolution up to 11 ps and an interval range up to 8 s.

Design of time interval generator based on hybrid counting method

Energy Technology Data Exchange (ETDEWEB)

Yao, Yuan [State Key Laboratory of Particle Detection and Electronics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China); Wang, Zhaoqi [State Key Laboratory of Particle Detection and Electronics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Lu, Houbing [State Key Laboratory of Particle Detection and Electronics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Hefei Electronic Engineering Institute, Hefei 230037 (China); Chen, Lian [State Key Laboratory of Particle Detection and Electronics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Jin, Ge, E-mail: goldjin@ustc.edu.cn [State Key Laboratory of Particle Detection and Electronics, University of Science and Technology of China, Hefei, Anhui 230026 (China)

2016-10-01

Time Interval Generators (TIGs) are frequently used for the characterizations or timing operations of instruments in particle physics experiments. Though some “off-the-shelf” TIGs can be employed, the necessity of a custom test system or control system makes the TIGs, being implemented in a programmable device desirable. Nowadays, the feasibility of using Field Programmable Gate Arrays (FPGAs) to implement particle physics instrumentation has been validated in the design of Time-to-Digital Converters (TDCs) for precise time measurement. The FPGA-TDC technique is based on the architectures of Tapped Delay Line (TDL), whose delay cells are down to few tens of picosecond. In this case, FPGA-based TIGs with high delay step are preferable allowing the implementation of customized particle physics instrumentations and other utilities on the same FPGA device. A hybrid counting method for designing TIGs with both high resolution and wide range is presented in this paper. The combination of two different counting methods realizing an integratable TIG is described in detail. A specially designed multiplexer for tap selection is emphatically introduced. The special structure of the multiplexer is devised for minimizing the different additional delays caused by the unpredictable routings from different taps to the output. A Kintex-7 FPGA is used for the hybrid counting-based implementation of a TIG, providing a resolution up to 11 ps and an interval range up to 8 s.

Graphite nodule count and size distribution in thin-walled ductile cast iron

DEFF Research Database (Denmark)

Pedersen, Karl Martin; Tiedje, Niels Skat

2008-01-01

Graphite nodule count and size distribution have been analysed in thin walled ductile cast iron. The 2D nodule counts have been converted into 3D nodule count by using Finite Difference Method (FDM). Particles having a diameter smaller than 5 µm should be neglected in the nodule count as these ar......Graphite nodule count and size distribution have been analysed in thin walled ductile cast iron. The 2D nodule counts have been converted into 3D nodule count by using Finite Difference Method (FDM). Particles having a diameter smaller than 5 µm should be neglected in the nodule count...... as these are inclusions and micro porosities that do not influence the solidification morphology. If there are many small graphite nodules as in thin walled castings only 3D nodule count calculated by FDM will give reliable results. 2D nodule count and 3D nodule count calculated by simple equations will give too low...

Fringe counting method for synthetic phase with frequency-modulated laser diodes

International Nuclear Information System (INIS)

Onodera, Ribun; Sakuyama, Munechika; Ishii, Yukihiro

2007-01-01

Fringe counting method with laser diodes (LDs) for displacement measurement has been constructed. Two LDs are frequency modulated by mutually inverted sawtooth currents on an unbalanced two-beam interferometer. The mutually inverted sawtooth-current modulation of LDs produces interference fringe signals with opposite signs for respective wavelengths. The two fringe signals are fed to an electronic mixer to produce a synthetic fringe signal with a reduced sensitivity to the synthetic wavelength. Synthetic fringe pulses derived from the synthetic fringe signal make a fringe counting system possible for faster movement of the tested mirror

Application of the activation analysis using the method of retarded fission neutrons counting for the determination of some fissionable nuclides

International Nuclear Information System (INIS)

Armelin, M.J.A.

1984-01-01

A system for the detection and counting of delayed neutrons which allows the analysis of some fissile and fertile nuclides, in samples of milligram size, was developed. This was applied for the analysis of natural uranium and thorium and also for determining the 235 U/ 238 U ratio in non-irradiated samples which contain uranium with different degrees of enrichment in 235 U. The spectrum of activated neutrons was varied in order to discriminate the nuclides, by covering or not the sample with a material (cadmium or boron) able to absorb low energy neutrons. Determination of 235 U/ 238 U ratios, through the number of delayed neutrons, was made by drawing a calibration curve using standards ranging from 0.5% to 93% on 235 U; the accuracy of the method was also examined. In a first step, conditions for a simultaneous and non-destructive analysis of uranium and thorium were developed. The interference between these two nuclides was studied, using simulated samples. Real samples were provided by Nuclemon and IAEA. For samples with uranium concentration in the range of percentages and thorium concentration of some ppm, uranium interferes in the determination of thorium through the non-destructive analytical method. For this case, a fast and quantitative chemical method was studied which allows for the separation of thorium from uranium before the determination of throrium concentration by counting the delayed fission neutrons. It was found that the results obtained by both destructive and non-destructive methods are very consistent and can be considered statistically equivalent within a confidence level of 95%. (Author) [pt

Fitting a distribution to miccrobial counts: making sense of zeros

DEFF Research Database (Denmark)

Ribeiro Duarte, Ana Sofia; Stockmarr, Anders; Nauta, Maarten

and standard deviation) and the prevalence of contaminated food units (one minus the proportion of “true zeros”) from a set of microbial counts. By running the model with in silico generated concentration and count data, we could evaluate the performance of this method in terms of estimation of the three......Non-detects or left-censored results are inherent to the traditional methods of microbial enumeration in foods. Typically, a low concentration of microorganisms in a food unit goes undetected in plate counts or most probable number (MPN) counts, and produces “artificial zeros”. However......, these “artificial zeros” are only a share of the total number of zero counts resulting from a sample, as their number adds up to the number of “true zeros” resulting from uncontaminated units. In the process of fitting a probability distribution to microbial counts, “artificial” and “true” zeros are usually...

Low-noise low-jitter 32-pixels CMOS single-photon avalanche diodes array for single-photon counting from 300 nm to 900 nm

Energy Technology Data Exchange (ETDEWEB)

Scarcella, Carmelo; Tosi, Alberto, E-mail: alberto.tosi@polimi.it; Villa, Federica; Tisa, Simone; Zappa, Franco [Politecnico di Milano, Dipartimento di Elettronica, Informazione e Bioingegneria, Piazza Leonardo da Vinci 32, I-20133 Milano (Italy)

2013-12-15

We developed a single-photon counting multichannel detection system, based on a monolithic linear array of 32 CMOS SPADs (Complementary Metal-Oxide-Semiconductor Single-Photon Avalanche Diodes). All channels achieve a timing resolution of 100 ps (full-width at half maximum) and a photon detection efficiency of 50% at 400 nm. Dark count rate is very low even at room temperature, being about 125 counts/s for 50 μm active area diameter SPADs. Detection performance and microelectronic compactness of this CMOS SPAD array make it the best candidate for ultra-compact time-resolved spectrometers with single-photon sensitivity from 300 nm to 900 nm.

Generating ActiGraph counts from raw acceleration recorded by an alternative monitor

DEFF Research Database (Denmark)

Brønd, Jan Christian; Andersen, Lars Bo; Arvidsson, Daniel

2017-01-01

Introduction: Raw acceleration data collected by the ActiGraph accelerometer is aggregated using a proprietary method into arbitrary physical activity intensity units called counts, which has been extensively calibrated and validated against energy expenditure. Generating ActiGraph counts from any...... second across all rotational frequencies compared to the original ActiGraph method. Applying the aggregation method to the 24-hour free-living recordings resulted in an epoch level bias ranging from -16.2 to 0.9 counts per 10 second, a relative difference in the averaged physical activity (counts per...

Determining random counts in liquid scintillation counting

International Nuclear Information System (INIS)

Horrocks, D.L.

1979-01-01

During measurements involving coincidence counting techniques, errors can arise due to the detection of chance or random coincidences in the multiple detectors used. A method and the electronic circuits necessary are here described for eliminating this source of error in liquid scintillation detectors used in coincidence counting. (UK)

Compton suppression gamma-counting: The effect of count rate

Science.gov (United States)

Millard, H.T.

1984-01-01

Past research has shown that anti-coincidence shielded Ge(Li) spectrometers enhanced the signal-to-background ratios for gamma-photopeaks, which are situated on high Compton backgrounds. Ordinarily, an anti- or non-coincidence spectrum (A) and a coincidence spectrum (C) are collected simultaneously with these systems. To be useful in neutron activation analysis (NAA), the fractions of the photopeak counts routed to the two spectra must be constant from sample to sample to variations must be corrected quantitatively. Most Compton suppression counting has been done at low count rate, but in NAA applications, count rates may be much higher. To operate over the wider dynamic range, the effect of count rate on the ratio of the photopeak counts in the two spectra (A/C) was studied. It was found that as the count rate increases, A/C decreases for gammas not coincident with other gammas from the same decay. For gammas coincident with other gammas, A/C increases to a maximum and then decreases. These results suggest that calibration curves are required to correct photopeak areas so quantitative data can be obtained at higher count rates. ?? 1984.

Edge detection of optical subaperture image based on improved differential box-counting method

Science.gov (United States)

Li, Yi; Hui, Mei; Liu, Ming; Dong, Liquan; Kong, Lingqin; Zhao, Yuejin

2018-01-01

Optical synthetic aperture imaging technology is an effective approach to improve imaging resolution. Compared with monolithic mirror system, the image of optical synthetic aperture system is often more complex at the edge, and as a result of the existence of gap between segments, which makes stitching becomes a difficult problem. So it is necessary to extract the edge of subaperture image for achieving effective stitching. Fractal dimension as a measure feature can describe image surface texture characteristics, which provides a new approach for edge detection. In our research, an improved differential box-counting method is used to calculate fractal dimension of image, then the obtained fractal dimension is mapped to grayscale image to detect edges. Compared with original differential box-counting method, this method has two improvements as follows: by modifying the box-counting mechanism, a box with a fixed height is replaced by a box with adaptive height, which solves the problem of over-counting the number of boxes covering image intensity surface; an image reconstruction method based on super-resolution convolutional neural network is used to enlarge small size image, which can solve the problem that fractal dimension can't be calculated accurately under the small size image, and this method may well maintain scale invariability of fractal dimension. The experimental results show that the proposed algorithm can effectively eliminate noise and has a lower false detection rate compared with the traditional edge detection algorithms. In addition, this algorithm can maintain the integrity and continuity of image edge in the case of retaining important edge information.

Effects of calibration methods on quantitative material decomposition in photon-counting spectral computed tomography using a maximum a posteriori estimator.

Science.gov (United States)

Curtis, Tyler E; Roeder, Ryan K

2017-10-01

Advances in photon-counting detectors have enabled quantitative material decomposition using multi-energy or spectral computed tomography (CT). Supervised methods for material decomposition utilize an estimated attenuation for each material of interest at each photon energy level, which must be calibrated based upon calculated or measured values for known compositions. Measurements using a calibration phantom can advantageously account for system-specific noise, but the effect of calibration methods on the material basis matrix and subsequent quantitative material decomposition has not been experimentally investigated. Therefore, the objective of this study was to investigate the influence of the range and number of contrast agent concentrations within a modular calibration phantom on the accuracy of quantitative material decomposition in the image domain. Gadolinium was chosen as a model contrast agent in imaging phantoms, which also contained bone tissue and water as negative controls. The maximum gadolinium concentration (30, 60, and 90 mM) and total number of concentrations (2, 4, and 7) were independently varied to systematically investigate effects of the material basis matrix and scaling factor calibration on the quantitative (root mean squared error, RMSE) and spatial (sensitivity and specificity) accuracy of material decomposition. Images of calibration and sample phantoms were acquired using a commercially available photon-counting spectral micro-CT system with five energy bins selected to normalize photon counts and leverage the contrast agent k-edge. Material decomposition of gadolinium, calcium, and water was performed for each calibration method using a maximum a posteriori estimator. Both the quantitative and spatial accuracy of material decomposition were most improved by using an increased maximum gadolinium concentration (range) in the basis matrix calibration; the effects of using a greater number of concentrations were relatively small in

Characteristic performance evaluation of a photon counting Si strip detector for low dose spectral breast CT imaging

Science.gov (United States)

Cho, Hyo-Min; Barber, William C.; Ding, Huanjun; Iwanczyk, Jan S.; Molloi, Sabee

2014-01-01

Purpose: The possible clinical applications which can be performed using a newly developed detector depend on the detector's characteristic performance in a number of metrics including the dynamic range, resolution, uniformity, and stability. The authors have evaluated a prototype energy resolved fast photon counting x-ray detector based on a silicon (Si) strip sensor used in an edge-on geometry with an application specific integrated circuit to record the number of x-rays and their energies at high flux and fast frame rates. The investigated detector was integrated with a dedicated breast spectral computed tomography (CT) system to make use of the detector's high spatial and energy resolution and low noise performance under conditions suitable for clinical breast imaging. The aim of this article is to investigate the intrinsic characteristics of the detector, in terms of maximum output count rate, spatial and energy resolution, and noise performance of the imaging system. Methods: The maximum output count rate was obtained with a 50 W x-ray tube with a maximum continuous output of 50 kVp at 1.0 mA. A109Cd source, with a characteristic x-ray peak at 22 keV from Ag, was used to measure the energy resolution of the detector. The axial plane modulation transfer function (MTF) was measured using a 67 μm diameter tungsten wire. The two-dimensional (2D) noise power spectrum (NPS) was measured using flat field images and noise equivalent quanta (NEQ) were calculated using the MTF and NPS results. The image quality parameters were studied as a function of various radiation doses and reconstruction filters. The one-dimensional (1D) NPS was used to investigate the effect of electronic noise elimination by varying the minimum energy threshold. Results: A maximum output count rate of 100 million counts per second per square millimeter (cps/mm2) has been obtained (1 million cps per 100 × 100 μm pixel). The electrical noise floor was less than 4 keV. The energy resolution

Selection of non-destructive assay methods: Neutron counting or calorimetric assay?

International Nuclear Information System (INIS)

Cremers, T.L.; Wachter, J.R.

1994-01-01

The transition of DOE facilities from production to D ampersand D has lead to more measurements of product, waste, scrap, and other less attractive materials. Some of these materials are difficult to analyze by either neutron counting or calorimetric assay. To determine the most efficacious analysis method, variety of materials, impure salts and hydrofluorination residues have been assayed by both calorimetric assay and neutron counting. New data will be presented together with a review of published data. The precision and accuracy of these measurements are compared to chemistry values and are reported. The contribution of the gamma ray isotopic determination measurement to the overall error of the calorimetric assay or neutron assay is examined and discussed. Other factors affecting selection of the most appropriate non-destructive assay method are listed and considered

Improvements on the determination of low level of tritium by liquid scintillation counting

International Nuclear Information System (INIS)

Pujol, L.; Suarez-Navarro, J. A.; Diaz, M. F

2002-01-01

Tritium is an essential tool for hydrological investigations such as the identification of modern recharge in aquifers, the estimation of hydraulic parameters related to pollutant transfer and the determination of the turnover time of groundwater. natural tritium is produced in the upper atmosphere from the interaction of cosmic radiation with atmospheric gases. The nuclear tests carried out in the 1959s and 1960s into the atmosphere increased the natural levels of tritium. Since the maximum of bomb 3H reached in the early 1960s, the tritium content of precipitation has decreased, and during the last few years, has approached to natural levels. Therefore, the demand for analysis of tritium in a large number of water samples and of decreasing tritium concentration has stimulated the development of electrolysis as the most practical and economical tritium enrichment method. Nevertheless, in some ground water systems and in the oceans, the tritium concentration is near the detection limit. There is therefore an urgent need to achieve a higher level of sensitivity for measurements. (Author) 6 refs

Increased tissue leptin hormone level and mast cell count in skin tags: A possible role of adipoimmune in the growth of benign skin growths

Directory of Open Access Journals (Sweden)

El Safoury Omar

2010-01-01

Full Text Available Background: Skin tags (ST are common tumors. They mainly consist of loose fibrous tissue and occur on the neck and major flexures as small, soft, pedunculated protrusions. Decrease in endocrine, hormone level and other factors are thought to play a role in the evolution of ST. Leptin is an adipocyte-derived hormone that acts as a major regulatory hormone for food intake and energy homeostasis. Leptin deficiency or resistance can result in profound obesity and diabetes in humans. A role of mast cell in the pathogenesis of ST is well recognized. Aims: To investigate the role of leptin in the pathogenesis of ST and to clarify whether there is a correlation between mast cell count and leptin level in ST. Methods: Forty-five skin biopsies were taken from 15 patients with ST. From each patient, a biopsy of a large ST (length >4 mm, a small ST (length <2 mm and a normal skin biopsy (as a control were taken. The samples were processed for leptin level. Skin biopsies were stained with hematoxylin and eosin and toluidine blue-uranyl nitrate metachromatic method for mast cell count was used. Results: There was a significant increased level of leptin in the ST compared to the normal skin. It was highly significant in small ST than in big ST (P = 0.0001 and it was highly significant in small and big ST compared to controls, P = 0.0001 and P = 0.001, respectively. There was a significant increase in mast cell count in the ST, which did not correlate with the increased levels of leptin. Conclusion: This is the first report to demonstrate that tissue leptin may play a role in the pathogenesis of ST. The significant increase in the levels of leptin and mast cell count in ST may indicate a possible role of adipoimmune in the benign skin growths.

Automated cell counts on CSF samples: A multicenter performance evaluation of the GloCyte system.

Science.gov (United States)

Hod, E A; Brugnara, C; Pilichowska, M; Sandhaus, L M; Luu, H S; Forest, S K; Netterwald, J C; Reynafarje, G M; Kratz, A

2018-02-01

Automated cell counters have replaced manual enumeration of cells in blood and most body fluids. However, due to the unreliability of automated methods at very low cell counts, most laboratories continue to perform labor-intensive manual counts on many or all cerebrospinal fluid (CSF) samples. This multicenter clinical trial investigated if the GloCyte System (Advanced Instruments, Norwood, MA), a recently FDA-approved automated cell counter, which concentrates and enumerates red blood cells (RBCs) and total nucleated cells (TNCs), is sufficiently accurate and precise at very low cell counts to replace all manual CSF counts. The GloCyte System concentrates CSF and stains RBCs with fluorochrome-labeled antibodies and TNCs with nucleic acid dyes. RBCs and TNCs are then counted by digital image analysis. Residual adult and pediatric CSF samples obtained for clinical analysis at five different medical centers were used for the study. Cell counts were performed by the manual hemocytometer method and with the GloCyte System following the same protocol at all sites. The limits of the blank, detection, and quantitation, as well as precision and accuracy of the GloCyte, were determined. The GloCyte detected as few as 1 TNC/μL and 1 RBC/μL, and reliably counted as low as 3 TNCs/μL and 2 RBCs/μL. The total coefficient of variation was less than 20%. Comparison with cell counts obtained with a hemocytometer showed good correlation (>97%) between the GloCyte and the hemocytometer, including at very low cell counts. The GloCyte instrument is a precise, accurate, and stable system to obtain red cell and nucleated cell counts in CSF samples. It allows for the automated enumeration of even very low cell numbers, which is crucial for CSF analysis. These results suggest that GloCyte is an acceptable alternative to the manual method for all CSF samples, including those with normal cell counts. © 2017 John Wiley & Sons Ltd.

Liquid Scintillation counting Standardization of 22 NaCl by the CIEMAT/NIST method

International Nuclear Information System (INIS)

Rodriguez Barquero, L.; Grau Carles, A.; Grau Malonda, A.

1995-09-01

We describe a procedure for preparing a stable solution of ''22 NaCl for liquid scintillation counting and its counting stability and spectral evolution in Insta-Gel''R is studied. The solution has been standardised in terms of activity concentration by the CIEMAT/NIST method with discrepancies between experimental and computed efficiencies lower than 0.4/% and an overall uncertainty of 0.35%

Selection of liquid-level monitoring method for the Oak Ridge National Laboratory inactive liquid low-level waste tanks, remedial investigation/feasibility study

International Nuclear Information System (INIS)

1994-11-01

Several of the inactive liquid low-level waste (LLLW) tanks at Oak Ridge National Laboratory contain residual wastes in liquid or solid (sludge) form or both. A plan of action has been developed to ensure that potential environmental impacts from the waste remaining in the inactive LLLW tank systems are minimized. This document describes the evaluation and selection of a methodology for monitoring the level of the liquid in inactive LLLW tanks. Criteria are established for comparison of existing level monitoring and leak testing methods; a preferred method is selected and a decision methodology for monitoring the level of the liquid in the tanks is presented for implementation. The methodology selected can be used to continuously monitor the tanks pending disposition of the wastes for treatment and disposal. Tanks that are empty, are scheduled to be emptied in the near future, or have liquid contents that are very low risk to the environment were not considered to be candidates for installing level monitoring. Tanks requiring new monitoring equipment were provided with conductivity probes; tanks with existing level monitoring instrumentation were not modified. The resulting data will be analyzed to determine inactive LLLW tank liquid level trends as a function of time

Bird biodiversity assessments in temperate forest: the value of point count versus acoustic monitoring protocols

Directory of Open Access Journals (Sweden)

Brian T. Klingbeil

2015-05-01

Full Text Available Effective monitoring programs for biodiversity are needed to assess trends in biodiversity and evaluate the consequences of management. This is particularly true for birds and faunas that occupy interior forest and other areas of low human population density, as these are frequently under-sampled compared to other habitats. For birds, Autonomous Recording Units (ARUs have been proposed as a supplement or alternative to point counts made by human observers to enhance monitoring efforts. We employed two strategies (i.e., simultaneous-collection and same-season to compare point count and ARU methods for quantifying species richness and composition of birds in temperate interior forests. The simultaneous-collection strategy compares surveys by ARUs and point counts, with methods matched in time, location, and survey duration such that the person and machine simultaneously collect data. The same-season strategy compares surveys from ARUs and point counts conducted at the same locations throughout the breeding season, but methods differ in the number, duration, and frequency of surveys. This second strategy more closely follows the ways in which monitoring programs are likely to be implemented. Site-specific estimates of richness (but not species composition differed between methods; however, the nature of the relationship was dependent on the assessment strategy. Estimates of richness from point counts were greater than estimates from ARUs in the simultaneous-collection strategy. Woodpeckers in particular, were less frequently identified from ARUs than point counts with this strategy. Conversely, estimates of richness were lower from point counts than ARUs in the same-season strategy. Moreover, in the same-season strategy, ARUs detected the occurrence of passerines at a higher frequency than did point counts. Differences between ARU and point count methods were only detected in site-level comparisons. Importantly, both methods provide similar

Precise method for correcting count-rate losses in scintillation cameras

International Nuclear Information System (INIS)

Madsen, M.T.; Nickles, R.J.

1986-01-01

Quantitative studies performed with scintillation detectors often require corrections for lost data because of the finite resolving time of the detector. Methods that monitor losses by means of a reference source or pulser have unacceptably large statistical fluctuations associated with their correction factors. Analytic methods that model the detector as a paralyzable system require an accurate estimate of the system resolving time. Because the apparent resolving time depends on many variables, including the window setting, source distribution, and the amount of scattering material, significant errors can be introduced by relying on a resolving time obtained from phantom measurements. These problems can be overcome by curve-fitting the data from a reference source to a paralyzable model in which the true total count rate in the selected window is estimated from the observed total rate. The resolving time becomes a free parameter in this method which is optimized to provide the best fit to the observed reference data. The fitted curve has the inherent accuracy of the reference source method with the precision associated with the observed total image count rate. Correction factors can be simply calculated from the ratio of the true reference source rate and the fitted curve. As a result, the statistical uncertainty of the data corrected by this method is not significantly increased

Low-priced, time-saving, reliable and stable LR-115 counting system

International Nuclear Information System (INIS)

Tchorz-Trzeciakiewicz, D.E.

2015-01-01

Nuclear alpha particles leave etches (tracks) when they hit the surface of a LR-115 detector. The density of these tracks is used to measure radon concentration. Counting these tracks by human sense is tedious and time-consuming procedure and may introduce counting error, whereas most available automatic and semiautomatic counting systems are expensive or complex. An uncomplicated, robust, reliable and stable counting system using freely available on the Internet software as Digimizer™ and PhotoScape was developed and proposed. The effectiveness of the proposed procedure was evaluated by comparing the amount of tracks counted by software with the amount of tracks counted manually for 223 detectors. The percentage error for each analysed detector was obtained as a difference between automatic and manual counts divided by manual count. For more than 97% of detectors, the percentage errors oscillated between −3% and 3%. - Highlights: • Semiautomatic, uncomplicated procedure was proposed to count the amount of alpha tracks. • Freely available software on the Internet used as alpha tracks counting system for LR-115. • LR-115 detectors used to measure radon concentration and radon exhalation rate

White blood cell and platelet count as adjuncts to standard clinical evaluation for risk assessment in patients at low probability of acute aortic syndrome.

Science.gov (United States)

Morello, Fulvio; Cavalot, Giulia; Giachino, Francesca; Tizzani, Maria; Nazerian, Peiman; Carbone, Federica; Pivetta, Emanuele; Mengozzi, Giulio; Moiraghi, Corrado; Lupia, Enrico

2017-08-01

Pre-test probability assessment is key in the approach to suspected acute aortic syndromes (AASs). However, most patients with AAS-compatible symptoms are classified at low probability, warranting further evaluation for decision on aortic imaging. White blood cell count, platelet count and fibrinogen explore pathophysiological pathways mobilized in AASs and are routinely assayed in the workup of AASs. However, the diagnostic performance of these variables for AASs, alone and as a bundle, is unknown. We tested the hypothesis that white blood cell count, platelet count and/or fibrinogen at presentation may be applied as additional tools to standard clinical evaluation for pre-test risk assessment in patients at low probability of AAS. This was a retrospective observational study conducted on consecutive patients managed in our Emergency Department from 2009 to 2014 for suspected AAS. White blood cell count, platelet count and fibrinogen were assayed during evaluation in the Emergency Department. The final diagnosis was obtained by computed tomography angiography. The pre-test probability of AAS was defined according to guidelines. Of 1210 patients with suspected AAS, 1006 (83.1%) were classified at low probability, and 271 (22.4%) were diagnosed with AAS. Within patients at low probability, presence of at least one alteration among white blood cell count >9*10 3 /µl, platelet count probability, white blood cell count >9*10 3 /µl and platelet count probability, the estimated risk of AAS based on the number of alterations amongst white blood cell count >9*10 3 /µl and platelet count probability to fine-tune risk assessment of AAS.

Liquid Scintillation Counting Standardization of 22NaCl by te CIEMAT/NIST method

International Nuclear Information System (INIS)

Rodriguez Barquero, L.; Grau Carles, A.; Grau Malonda, A.

1995-01-01

We describe a procedure for preparing a stable solution of ''22NaCl for liquid scintillation counting and its counting stability and spectral evolution in Insta-Gel''R is studied. The solution has been standardised in terms of activity concentration by the CIEMAT/NIST method with discrepancies between experimental and computed efficiencies lower than 0.4 % and an overall uncertainty of 0.35 %. (Author) 4 refs

The Drigg low-level waste site

International Nuclear Information System (INIS)

1992-01-01

Safe disposal of waste is a vital aspect of any industrial operation whether it be production of plastics, steel or chemicals or handling of radioactive materials. Appropriate methods must be used in every case. Radioactive waste falls into three distinct categories - high, intermediate and low-level. It is the solid low-level waste making up over 90% of the total which this booklet discusses. British Nuclear Fuels plc (BNFL) operates a site for the disposal of solid low-level waste at Driggs, some six kilometres south of Sellafield in West Cumbria. The daily operations and control of the site, the responsibility of the BNFL Waste Management Unit is described. (author)

A method for the determination of counting efficiencies in γ-spectrometric measurements with HPGe detectors

International Nuclear Information System (INIS)

Bolivar, J.P.; Garcia-Leon, M.

1996-01-01

In this paper a general method for γ-ray efficiency calibration is presented. The method takes into account the differences of densities and counting geometry between the real sample and the calibration sample. It is based on the γ-transmission method and gives the correction factor f as a function of E γ , the density and counting geometry. Altough developed for soil samples, its underlying working philosophy is useful for any sample whose geometry can be adequately reproduced. (orig.)

Pixel-Cluster Counting Luminosity Measurement in ATLAS

CERN Document Server

McCormack, William Patrick; The ATLAS collaboration

2016-01-01

A precision measurement of the delivered luminosity is a key component of the ATLAS physics program at the Large Hadron Collider (LHC). A fundamental ingredient of the strategy to control the systematic uncertainties affecting the absolute luminosity has been to compare the measurements of several luminometers, most of which use more than one counting technique. The level of consistency across the various methods provides valuable cross-checks as well as an estimate of the detector-related systematic uncertainties. This poster describes the development of a luminosity algorithm based on pixel-cluster counting in the recently installed ATLAS inner b-layer (IBL), using data recorded during the 2015 pp run at the LHC. The noise and background contamination of the luminosity-associated cluster count is minimized by a multi-component fit to the measured cluster-size distribution in the forward pixel modules of the IBL. The linearity, long-term stability and statistical precision of the cluster-counting method are ...

Pixel-Cluster Counting Luminosity Measurement In ATLAS

CERN Document Server

AUTHOR|(SzGeCERN)782710; The ATLAS collaboration

2017-01-01

A precision measurement of the delivered luminosity is a key component of the ATLAS physics program at the Large Hadron Collider (LHC). A fundamental ingredient of the strategy to control the systematic uncertainties affecting the absolute luminosity has been to compare the measure- ments of several luminometers, most of which use more than one counting technique. The level of consistency across the various methods provides valuable cross-checks as well as an estimate of the detector-related systematic uncertainties. This poster describes the development of a luminosity algorithm based on pixel-cluster counting in the recently installed ATLAS inner b-layer (IBL), using data recorded during the 2015 pp run at the LHC. The noise and background contamination of the luminosity-associated cluster count is minimized by a multi-component fit to the measured cluster-size distribution in the forward pixel modules of the IBL. The linearity, long-term stability and statistical precision of the cluster- counting method a...

Three-dimensional passive sensing photon counting for object classification

Science.gov (United States)

Yeom, Seokwon; Javidi, Bahram; Watson, Edward

2007-04-01

In this keynote address, we address three-dimensional (3D) distortion-tolerant object recognition using photon-counting integral imaging (II). A photon-counting linear discriminant analysis (LDA) is discussed for classification of photon-limited images. We develop a compact distortion-tolerant recognition system based on the multiple-perspective imaging of II. Experimental and simulation results have shown that a low level of photons is sufficient to classify out-of-plane rotated objects.

Combinatorial nuclear level density by a Monte Carlo method

International Nuclear Information System (INIS)

Cerf, N.

1994-01-01

We present a new combinatorial method for the calculation of the nuclear level density. It is based on a Monte Carlo technique, in order to avoid a direct counting procedure which is generally impracticable for high-A nuclei. The Monte Carlo simulation, making use of the Metropolis sampling scheme, allows a computationally fast estimate of the level density for many fermion systems in large shell model spaces. We emphasize the advantages of this Monte Carlo approach, particularly concerning the prediction of the spin and parity distributions of the excited states,and compare our results with those derived from a traditional combinatorial or a statistical method. Such a Monte Carlo technique seems very promising to determine accurate level densities in a large energy range for nuclear reaction calculations

Association of psychological stress response of fatigue with white blood cell count in male daytime workers.

Science.gov (United States)

Nishitani, Naoko; Sakakibara, Hisataka

2014-01-01

Relationships between work-related psychological and physical stress responses and counts of white blood cells (WBCs), neutrophils, and lymphocytes were investigated in 101 daytime workers. Counts of WBCs and neutrophils were positively associated with smoking and inversely correlated with high density lipoprotein (HDL)-cholesterol levels. Additionally, general fatigue score as measured by the profile of mood state was positively correlated with WBC and neutrophil counts whereas lymphocyte counts was not significantly associated with fatigue score. Multiple regression analysis showed that WBC count was significantly related to general fatigue, age, and HDL-cholesterol levels. Neutrophil count was significantly related to HDL-cholesterol levels and fatigue score. Among various psychological stress response variables, general fatigue may be a key determinant of low-grade inflammation as represented by increases of WBC and neutrophil counts.

High resolution micro-CT of low attenuating organic materials using large area photon-counting detector

International Nuclear Information System (INIS)

Kumpová, I.; Jandejsek, I.; Jakůbek, J.; Vopálenský, M.; Vavřík, D.; Fíla, T.; Koudelka, P.; Kytýř, D.; Zlámal, P.; Gantar, A.

2016-01-01

To overcome certain limitations of contemporary materials used for bone tissue engineering, such as inflammatory response after implantation, a whole new class of materials based on polysaccharide compounds is being developed. Here, nanoparticulate bioactive glass reinforced gelan-gum (GG-BAG) has recently been proposed for the production of bone scaffolds. This material offers promising biocompatibility properties, including bioactivity and biodegradability, with the possibility of producing scaffolds with directly controlled microgeometry. However, to utilize such a scaffold with application-optimized properties, large sets of complex numerical simulations using the real microgeometry of the material have to be carried out during the development process. Because the GG-BAG is a material with intrinsically very low attenuation to X-rays, its radiographical imaging, including tomographical scanning and reconstructions, with resolution required by numerical simulations might be a very challenging task. In this paper, we present a study on X-ray imaging of GG-BAG samples. High-resolution volumetric images of investigated specimens were generated on the basis of micro-CT measurements using a large area flat-panel detector and a large area photon-counting detector. The photon-counting detector was composed of a 010× 1 matrix of Timepix edgeless silicon pixelated detectors with tiling based on overlaying rows (i.e. assembled so that no gap is present between individual rows of detectors). We compare the results from both detectors with the scanning electron microscopy on selected slices in transversal plane. It has been shown that the photon counting detector can provide approx. 3× better resolution of the details in low-attenuating materials than the integrating flat panel detectors. We demonstrate that employment of a large area photon counting detector is a good choice for imaging of low attenuating materials with the resolution sufficient for numerical

High resolution micro-CT of low attenuating organic materials using large area photon-counting detector

Science.gov (United States)

Kumpová, I.; Vavřík, D.; Fíla, T.; Koudelka, P.; Jandejsek, I.; Jakůbek, J.; Kytýř, D.; Zlámal, P.; Vopálenský, M.; Gantar, A.

2016-02-01

To overcome certain limitations of contemporary materials used for bone tissue engineering, such as inflammatory response after implantation, a whole new class of materials based on polysaccharide compounds is being developed. Here, nanoparticulate bioactive glass reinforced gelan-gum (GG-BAG) has recently been proposed for the production of bone scaffolds. This material offers promising biocompatibility properties, including bioactivity and biodegradability, with the possibility of producing scaffolds with directly controlled microgeometry. However, to utilize such a scaffold with application-optimized properties, large sets of complex numerical simulations using the real microgeometry of the material have to be carried out during the development process. Because the GG-BAG is a material with intrinsically very low attenuation to X-rays, its radiographical imaging, including tomographical scanning and reconstructions, with resolution required by numerical simulations might be a very challenging task. In this paper, we present a study on X-ray imaging of GG-BAG samples. High-resolution volumetric images of investigated specimens were generated on the basis of micro-CT measurements using a large area flat-panel detector and a large area photon-counting detector. The photon-counting detector was composed of a 010× 1 matrix of Timepix edgeless silicon pixelated detectors with tiling based on overlaying rows (i.e. assembled so that no gap is present between individual rows of detectors). We compare the results from both detectors with the scanning electron microscopy on selected slices in transversal plane. It has been shown that the photon counting detector can provide approx. 3× better resolution of the details in low-attenuating materials than the integrating flat panel detectors. We demonstrate that employment of a large area photon counting detector is a good choice for imaging of low attenuating materials with the resolution sufficient for numerical simulations.

Advanced time-correlated single photon counting applications

CERN Document Server

Becker, Wolfgang

2015-01-01

This book is an attempt to bridge the gap between the instrumental principles of multi-dimensional time-correlated single photon counting (TCSPC) and typical applications of the technique. Written by an originator of the technique and by sucessful users, it covers the basic principles of the technique, its interaction with optical imaging methods and its application to a wide range of experimental tasks in life sciences and clinical research. The book is recommended for all users of time-resolved detection techniques in biology, bio-chemistry, spectroscopy of live systems, live cell microscopy, clinical imaging, spectroscopy of single molecules, and other applications that require the detection of low-level light signals at single-photon sensitivity and picosecond time resolution.

Enhanced coulomb counting method for estimating state-of-charge and state-of-health of lithium-ion batteries

International Nuclear Information System (INIS)

Ng, Kong Soon; Moo, Chin-Sien; Chen, Yi-Ping; Hsieh, Yao-Ching

2009-01-01

The coulomb counting method is expedient for state-of-charge (SOC) estimation of lithium-ion batteries with high charging and discharging efficiencies. The charging and discharging characteristics are investigated and reveal that the coulomb counting method is convenient and accurate for estimating the SOC of lithium-ion batteries. A smart estimation method based on coulomb counting is proposed to improve the estimation accuracy. The corrections are made by considering the charging and operating efficiencies. Furthermore, the state-of-health (SOH) is evaluated by the maximum releasable capacity. Through the experiments that emulate practical operations, the SOC estimation method is verified to demonstrate the effectiveness and accuracy.

Determination of 90Sr in radioactive liquid waste-a comparative study using 'SrCO3 precipitation, extraction chromatography and Cerenkov radiation counting' techniques

International Nuclear Information System (INIS)

Mani, A.G.S.; Renganathan, K.; Rao, S.V.S.; Sinha, P.K.

2007-01-01

In the wastes generated at nuclear power plants, 90 Sr and 90 Y are responsible for approximately 7% and 38% of the total fission product activity after 1 year and 10 years respectively. Monitoring of the liquid waste produced in nuclear facilities for 90 Sr before and after releasing to the aquatic environment is essential, as it can cause a long term biological hazard due to its chemical similarity with Ca, high fission yield (5.9%) and long radioactive and biological half lives of 28 and 49.3 years respectively. As conventional carbonate precipitation method for 90 Sr- 90 Y estimation is laborious and time consuming, the other methods like extraction chromatography technique using strontium selective crown ether and Cerenkov radiation counting by liquid scintillation analyser (LSA) were also investigated. This paper describe procedures involved in the estimation of strontium in low-level radioactive liquid effluent by using above methods and deals with the comparison of results. Cerenkov radiation counting by LSA has an edge over the other methods in the determination of 90 Sr as it is a simple and rapid technique. Experiences gained in the estimation of 90 Sr in low-level radioactive liquid effluent using Cerenkov radiation counting technique is discussed in detail in this paper. (author)

An Economical Fast Discriminator for Nuclear Pulse Counting

International Nuclear Information System (INIS)

Issarachai, Opas; Punnachaiya, Suvit

2009-07-01

Full text: This research work was aimed to develop a fast discriminator at low cost but high capability for discrimination a nanosecond nuclear pulse. The fast discriminator can be used in association with fast photon counting system. The designed structure consisted of the ultra-fast voltage comparator using ADCMP601 integrated circuit, the monostable multivibrator with controllable pulse width output by propagation delay of logic gate, and the fast response buffer amplifier. The tested results of pulse height discrimination of 0-5 V nuclear pulse with 20 ns (FWHM) pulse width showed the correlation coefficient (R 2 ) between discrimination level and pulse height was 0.998, while the pulse rate more than 10 MHz could be counted. The 30 ns logic pulse width output revealed high stable and could be smoothly driven to low impedance load at 50 Ω. For pulse signal transmission to the counter, it was also found that the termination of reflected signal must be considered because it may cause pulse counting error

Can Detectability Analysis Improve the Utility of Point Counts for Temperate Forest Raptors?

Science.gov (United States)

Temperate forest breeding raptors are poorly represented in typical point count surveys because these birds are cryptic and typically breed at low densities. In recent years, many new methods for estimating detectability during point counts have been developed, including distanc...

Reconstructing the metric of the local Universe from number counts observations

Energy Technology Data Exchange (ETDEWEB)

Vallejo, Sergio Andres [ICRANet, Piazza della Repubblica 10, I-65122 Pescara (Italy); Romano, Antonio Enea, E-mail: antonio.enea.romano@cern.ch [Theoretical Physics Department, CERN, CH-1211 Geneva 23 (Switzerland)

2017-10-01

Number counts observations available with new surveys such as the Euclid mission will be an important source of information about the metric of the Universe. We compute the low red-shift expansion for the energy density and the density contrast using an exact spherically symmetric solution in presence of a cosmological constant. At low red-shift the expansion is more precise than linear perturbation theory prediction. We then use the local expansion to reconstruct the metric from the monopole of the density contrast. We test the inversion method using numerical calculations and find a good agreement within the regime of validity of the red-shift expansion. The method could be applied to observational data to reconstruct the metric of the local Universe with a level of precision higher than the one achievable using perturbation theory.

MOSS-5: A Fast Method of Approximating Counts of 5-Node Graphlets in Large Graphs

KAUST Repository

Wang, Pinghui

2017-09-26

Counting 3-, 4-, and 5-node graphlets in graphs is important for graph mining applications such as discovering abnormal/evolution patterns in social and biology networks. In addition, it is recently widely used for computing similarities between graphs and graph classification applications such as protein function prediction and malware detection. However, it is challenging to compute these metrics for a large graph or a large set of graphs due to the combinatorial nature of the problem. Despite recent efforts in counting triangles (a 3-node graphlet) and 4-node graphlets, little attention has been paid to characterizing 5-node graphlets. In this paper, we develop a computationally efficient sampling method to estimate 5-node graphlet counts. We not only provide fast sampling methods and unbiased estimators of graphlet counts, but also derive simple yet exact formulas for the variances of the estimators which is of great value in practice-the variances can be used to bound the estimates\\' errors and determine the smallest necessary sampling budget for a desired accuracy. We conduct experiments on a variety of real-world datasets, and the results show that our method is several orders of magnitude faster than the state-of-the-art methods with the same accuracy.

Low-level radioactive gas monitor for natural gas operations

International Nuclear Information System (INIS)

Armstrong, F.E.

1969-11-01

A portable radioactivity detection system for monitoring the tritium content of natural gas under field conditions has been developed. The sensing device employed is a complex proportional counting assembly operated without the use of massive shielding previously employed with such low-level radiation detectors. The practical limit of detection for the system is a tritium content of 10 -9 microcurie per cc of natural gas. All components of the system are packaged in three waterproof cases weighing slightly less than 30 kg each. Power requirement is 500 watts of 120 volt, 60 Hz current. Operation is fully automatic with a printed record produced at predetermined time intervals

Background compensated GM counter for the measurement of low level #betta#-activity

International Nuclear Information System (INIS)

Mori, C.; Kumanomido, H.; Watanabe, T.

1983-01-01

When low level activity of a #betta#-ray source or surface contamination is to be measured with a GM counter, it is desirable to obtain a net count without background count through a single measurement. An end-window GM counter for such a purpose was constructed. The counter has a diaphragm to divide it into two parts. The front part, the window side, can detect #betta#-rays and background radiations, while the rear part only detects background, since #betta#-rays coming through the front are absorbed by the diaphragm. In the counter type I, the sensitive volumes of the two parts are the same and the anode wire of the front is connected to that of the rear through an electric resistor which leads to yielding different pulse heights and rise times. The net count of #betta#-rays can be obtained through a single measurement by subtracting the count in the rear part from that in the front part. In the counter type II, the lengths of the anode wires of the two parts are different, which gives rise to different pulse heights. With a background compensated GM counter, it is possible to shorten the measuring time, keeping nearly the same accuracy compared with a conventional GM counter. (orig.)

Statistical method for resolving the photon-photoelectron-counting inversion problem

International Nuclear Information System (INIS)

Wu Jinlong; Li Tiejun; Peng, Xiang; Guo Hong

2011-01-01

A statistical inversion method is proposed for the photon-photoelectron-counting statistics in quantum key distribution experiment. With the statistical viewpoint, this problem is equivalent to the parameter estimation for an infinite binomial mixture model. The coarse-graining idea and Bayesian methods are applied to deal with this ill-posed problem, which is a good simple example to show the successful application of the statistical methods to the inverse problem. Numerical results show the applicability of the proposed strategy. The coarse-graining idea for the infinite mixture models should be general to be used in the future.

Screening of alternative methods for the disposal of low-level radioactive wastes

International Nuclear Information System (INIS)

Macbeth, P.J.; Thamer, B.J.; Christensen, D.E.; Wehmann, G.

1978-10-01

A systematic method for categorizing these disposal alternatives which provides assurance that no viable alternatives are overlooked is reported. Alternatives are categorized by (1) the general media in which disposal occurs, (2) by whether the disposal method can be considered as dispersal, containment or elimination of the wastes, and (3) by the applicability of the disposal method to the possible physical waste forms. A literature survey was performed and pertinent references listed for the various alternatives discussed. A bibliography is given which provides coverage of published information on low-level radioactive waste management options. The extensive list of disposal alternatives identified was screened and the most viable choices were selected for further evaluation. A Technical Advisory Panel met and reviewed the results. Suggestions from that meeting and other comments are discussed. The most viable options selected for further evaluation are: (1) improving present shallow land burial practices; (2) deeper depth burial; (3) disposal in cavities; (4) disposal in exposed or buried structures; and (5) ocean disposal. 42 references

Pulse-shape discrimination in radioanalytical methods. Part I. Delayed fission neutron counting

International Nuclear Information System (INIS)

Posta, S.; Vacik, J.; Hnatowicz, V.; Cervena, J.

1999-01-01

In this study the principle of pulse shape discrimination (PSD) has been employed in delayed fission neutron counting (DNC) method. Effective elimination of unwanted gamma background signals in measured radiation spectra has been proved. (author)

Drone-based Object Counting by Spatially Regularized Regional Proposal Network

OpenAIRE

Hsieh, Meng-Ru; Lin, Yen-Liang; Hsu, Winston H.

2017-01-01

Existing counting methods often adopt regression-based approaches and cannot precisely localize the target objects, which hinders the further analysis (e.g., high-level understanding and fine-grained classification). In addition, most of prior work mainly focus on counting objects in static environments with fixed cameras. Motivated by the advent of unmanned flying vehicles (i.e., drones), we are interested in detecting and counting objects in such dynamic environments. We propose Layout Prop...

Optimal Matched Filter in the Low-number Count Poisson Noise Regime and Implications for X-Ray Source Detection

Science.gov (United States)

Ofek, Eran O.; Zackay, Barak

2018-04-01

Detection of templates (e.g., sources) embedded in low-number count Poisson noise is a common problem in astrophysics. Examples include source detection in X-ray images, γ-rays, UV, neutrinos, and search for clusters of galaxies and stellar streams. However, the solutions in the X-ray-related literature are sub-optimal in some cases by considerable factors. Using the lemma of Neyman–Pearson, we derive the optimal statistics for template detection in the presence of Poisson noise. We demonstrate that, for known template shape (e.g., point sources), this method provides higher completeness, for a fixed false-alarm probability value, compared with filtering the image with the point-spread function (PSF). In turn, we find that filtering by the PSF is better than filtering the image using the Mexican-hat wavelet (used by wavdetect). For some background levels, our method improves the sensitivity of source detection by more than a factor of two over the popular Mexican-hat wavelet filtering. This filtering technique can also be used for fast PSF photometry and flare detection; it is efficient and straightforward to implement. We provide an implementation in MATLAB. The development of a complete code that works on real data, including the complexities of background subtraction and PSF variations, is deferred for future publication.

the effect of cd4 count level on the middle ear dynamics of hiv

African Journals Online (AJOL)

2014-01-01

Jan 1, 2014 ... THE EFFECT OF CD4 COUNT LEVEL ON THE MIDDLE EAR DYNAMICS OF HIV INFECTED PATIENTS .... compliance and pressure values were the ones causing ... of sound wave than in the control group (non-HIV infected ...

Low-level radwaste engineering economics

International Nuclear Information System (INIS)

Jacobs, M.H.; Miller, C.C.; Young, L.G.

1984-07-01

This topical report on engineering economics for low-level radwaste systems details the methodologies used for economic analyses of radwaste treatment systems and provides examples of radwaste economic evaluations. All of the parameters and cost items used in an evaluation are defined. Examples of the present-value-of-revenue-requirements method, levelized-revenue-requirements method, and the equivalent-capital-investment method are provided. Also, the calculation to determine the maximum justifiable capital expenditure for a radwaste system is illustrated. The report also provides examples of economic evaluations for many current radwaste treatment options. These options include evaporation versus demineralization, dewatering resins versus solidification of resins, and several volume reduction systems. 15 figures, 6 tables

Oral enclomiphene citrate stimulates the endogenous production of testosterone and sperm counts in men with low testosterone: comparison with testosterone gel.

Science.gov (United States)

Kaminetsky, Jed; Werner, Michael; Fontenot, Greg; Wiehle, Ronald D

2013-06-01

Clomiphene citrate is employed off-label in men who have low testosterone and for the restoration of sperm counts in men who have used exogenous testosterone. Clomiphene is a mixture of two diastereoisomers: zuclomiphene and enclomiphene. We evaluated enclomiphene citrate in men with secondary hypogonadism. Our aim was to compare oral enclomiphene citrate as an alternative to topical testosterone. Blood levels of total testosterone (TT), estradiol, follicle-stimulating hormone (FSH), luteinizing hormone (LH), sex hormone binding globulin, thyroid stimulation hormone, prolactin, and insulin-like growth factor 1 IGF-1 were measured at certain times after treatment with each agent. Sperm parameters were determined at the same visits. Free testosterone (FT) was calculated. This was a proof-of-principle, randomized, open-label, fixed dose, active-control, two-center phase IIB study in 12 men with secondary hypogonadism treated previously with topical testosterone. After discontinuation of topical testosterone, morning TT values averaged 165 ± 66 pg/dL. After 3 months, there was a significant rise in men receiving enclomiphene citrate and gel that was sustained for 3 months. At 6 months, TT levels were 545 ± 268 and 525 ± 256 pg/dL for groups receiving the gel and enclomiphene citrate, respectively. Only men in the enclomiphene citrate group demonstrated increased LH and FSH. TT decreased one month posttreatment to pretreatment values. Enclomiphene citrate elevated sperm counts in seven out of seven men at 3 months and six out of six men at 6 months with sperm concentrations in the 75-334 × 10(6) /mL range. The gel was ineffective in raising sperm counts above 20 × 10(6) /mL for all five men at 3 months and raised counts in only two or five men at 6 months. At follow-up, only enclomiphene citrate treatment was associated with elevated sperm counts. Enclomiphene citrate increased testosterone and sperm counts. Concomitant changes in LH and FSH suggest normalization

Low-level measurements with liquid scintillation spectrometry development and application

International Nuclear Information System (INIS)

Schoenhofer, F.

1997-01-01

Since the availability of a commerical low-level counter a large number of applications has been introduced, many well known applications have been improved. Here only a few typical examples can be given - mostly work done in the authors laboratory. The instruments used were the 'Quantulus' from Wallac Oy, Finland (we have four of them), vials were in nearly all cases PTFE-coated PE vials from Zinsser, Germany and the cocktails used were from Zinsser, Germany and Packard Instrument BV, Netherlands. All LLD's mentioned in this paper are based on 3 sigma of the background for a 500 min count. (orig.)

Low-level measurements with liquid scintillation spectrometry development and application

Energy Technology Data Exchange (ETDEWEB)

Schoenhofer, F [Federal Inst. for Food Control and Research, Vienna (Austria)

1997-03-01

Since the availability of a commerical low-level counter a large number of applications has been introduced, many well known applications have been improved. Here only a few typical examples can be given - mostly work done in the authors laboratory. The instruments used were the `Quantulus` from Wallac Oy, Finland (we have four of them), vials were in nearly all cases PTFE-coated PE vials from Zinsser, Germany and the cocktails used were from Zinsser, Germany and Packard Instrument BV, Netherlands. All LLD`s mentioned in this paper are based on 3 sigma of the background for a 500 min count. (orig.)

Treatment of uncertainty in low-level waste performance assessment

International Nuclear Information System (INIS)

Kozak, M.W.; Olague, N.E.; Gallegos, D.P.; Rao, R.R.

1991-01-01

Uncertainties arise from a number of different sources in low-level waste performance assessment. In this paper the types of uncertainty are reviewed, and existing methods for quantifying and reducing each type of uncertainty are discussed. These approaches are examined in the context of the current low-level radioactive waste regulatory performance objectives, which are deterministic. The types of uncertainty discussed in this paper are model uncertainty, uncertainty about future conditions, and parameter uncertainty. The advantages and disadvantages of available methods for addressing uncertainty in low-level waste performance assessment are presented. 25 refs

A New Method for Processing Airborne Gamma Ray Spectrometry Data for Mapping Low Level Contaminations

DEFF Research Database (Denmark)

Aage, Helle Karina; Korsbech, Uffe C C; Bargholz, Kim

1999-01-01

A new technique for processing airborne gamma ray spectrometry data has been developed. It is based on the noise adjusted singular value decomposition method introduced by Hovgaard in 1997. The new technique opens for mapping of very low contamination levels. It is tested with data from Latvia...... where the remaining contamination from the 1986 Chernobyl accident together with fallout from the atmospheric nuclear weapon tests includes Cs-137 at levels often well below 1 kBq/m(2) equivalent surface contamination. The limiting factors for obtaining reliable results are radon in the air, spectrum...

Automatic quench compensation for liquid scintillation counting system

International Nuclear Information System (INIS)

Nather, R.E.

1978-01-01

A method of automatic quench compensation is provided, where a reference measure of quench is taken on a sample prior to taking a sample count. The measure of quench is then compared with a reference voltage source which has been established to vary in proportion to the variation of the measure of quench with the level of a system parameter required to restore at least one isotope spectral energy endpoint substantially to a selected counting window discriminator level in order to determine the amount of adjustment of the system parameter required to restore the endpoint. This is followed by the appropriate adjustment of the system parameter required to restore the relative position of the discriminator windows and the sample spectrum and is followed in turn by taking a sample count

Records in ultra low radioactivity measurements with neutron activation analysis

International Nuclear Information System (INIS)

Hentig, R. von; Goldbrunner, T.; Angloher, G.; Feilitzsch, F. von

1999-01-01

Neutron Activation Analysis has emerged to be an analytical method sensitive enough to detect fg/g traces of unstable primordial nuclides in complex matrices. Especially low count rate experiments in the field of solar neutrino physics and dark matter search can profit from the detection capabilities of this method which had been unattained so far. This gain in sensitivity has been achieved by combining neutron activation, radiochemical separation methods, and efficient low level counting systems at the new underground laboratory of the accelerator laboratory in Garching. Recent improvements which have been made in the purification and analysis of the liquid scintillator, as foreseen for the solar neutrino experiment BOREXINO, are being presented as an example in this paper

Low-level laser therapy for the treatment of androgenic alopecia: a review.

Science.gov (United States)

Darwin, Evan; Heyes, Alexandra; Hirt, Penelope A; Wikramanayake, Tongyu Cao; Jimenez, Joaquin J

2018-02-01

There are many new low-level laser technologies that have been released commercially that claim to support hair regrowth. In this paper, we will examine the clinical trials to determine whether the body of evidence supports the use of low-level laser therapy (LLLT) to treat androgenic alopecia (AGA). A literature search was conducted through Pubmed, Embase, and Clinicaltrials.gov for clinical trials using LLLT to treat AGA. Thirteen clinical trials were assessed. Review articles were not included. Ten of 11 trials demonstrated significant improvement of androgenic alopecia in comparison to baseline or controls when treated with LLLT. In the remaining study, improvement in hair counts and hair diameter was recorded, but did not reach statistical significance. Two trials did not include statistical analysis, but showed marked improvement by hair count or by photographic evidence. Two trials showed efficacy for LLLT in combination with topical minoxidil. One trial showed efficacy when accompanying finasteride treatment. LLLT appears to be a safe, alternative treatment for patients with androgenic alopecia. Clinical trials have indicated efficacy for androgenic alopecia in both men and women. It may be used independently or as an adjuvant of minoxidil or finasteride. More research needs to be undertaken to determine the optimal power and wavelength to use in LLLT as well as LLLT's mechanism of action.

Development of low level 226Ra analysis for live fish using gamma-ray spectrometry

Science.gov (United States)

Chandani, Z.; Prestwich, W. V.; Byun, S. H.

2017-06-01

A low level 226Ra analysis method for live fish was developed using a 4π NaI(Tl) gamma-ray spectrometer. In order to find out the best algorithm for accomplishing the lowest detection limit, the gamma-ray spectrum from a 226Ra point was collected and nine different methods were attempted for spectral analysis. The lowest detection limit of 0.99 Bq for an hour counting occurred when the spectrum was integrated in the energy region of 50-2520 keV. To extend 226Ra analysis to live fish, a Monte Carlo simulation model with a cylindrical fish in a water container was built using the MCNP code. From simulation results, the spatial distribution of the efficiency and the efficiency correction factor for the live fish model were determined. The MCNP model will be able to be conveniently modified when a different fish or container geometry is employed as fish grow up in real experiments.

Assessment guidance of carbohydrate counting method in patients with type 2 diabetes mellitus.

Science.gov (United States)

Martins, Michelle R; Ambrosio, Ana Cristina T; Nery, Marcia; Aquino, Rita de Cássia; Queiroz, Marcia S

2014-04-01

We evaluated the application of the method of carbohydrate counting performed by 21 patients with type 2 diabetes, 1 year later attending a guidance course. Participants answered a questionnaire to assess patients' adhesion to carbohydrate counting as well as to identify habit changes and the method's applicability, and values of glycated hemoglobin were also analyzed. Most participants (76%) were females, and 25% of them had obesity degree III. There was a statistically significant decrease in glycated hemoglobin from 8.42±0.02% to 7.66±0.01% comparing values before and after counseling. We observed that although patients stated that the method was difficult they understood that carbohydrate counting could allow them make choices and have more freedom in their meals; we also verified if they understood accurately how to replace some foods used regularly in their diets and most patients correctly chose replacements for the groups of bread (76%), beans (67%) and noodles (67%). We concluded that participation in the course led to improved blood glucose control with a significant reduction of glycated hemoglobin, better understanding of food groups and the adoption of healthier eating habits. Copyright © 2013 Primary Care Diabetes Europe. Published by Elsevier Ltd. All rights reserved.

The Eosinophil Count Tends to Be Negatively Associated with Levels of Serum Glucose in Patients with Adrenal Cushing Syndrome.

Science.gov (United States)

Lee, Younghak; Yi, Hyon Seung; Kim, Hae Ri; Joung, Kyong Hye; Kang, Yea Eun; Lee, Ju Hee; Kim, Koon Soon; Kim, Hyun Jin; Ku, Bon Jeong; Shong, Minho

2017-09-01

Cushing syndrome is characterized by glucose intolerance, cardiovascular disease, and an enhanced systemic inflammatory response caused by chronic exposure to excess cortisol. Eosinopenia is frequently observed in patients with adrenal Cushing syndrome, but the relationship between the eosinophil count in peripheral blood and indicators of glucose level in patients with adrenal Cushing syndrome has not been determined. A retrospective study was undertaken of the clinical and laboratory findings of 40 patients diagnosed with adrenal Cushing syndrome at Chungnam National University Hospital from January 2006 to December 2016. Clinical characteristics, complete blood cell counts with white blood cell differential, measures of their endocrine function, description of imaging studies, and pathologic findings were obtained from their medical records. Eosinophil composition and count were restored by surgical treatment of all of the patients with adrenal Cushing disease. The eosinophil count was inversely correlated with serum and urine cortisol, glycated hemoglobin, and inflammatory markers in the patients with adrenal Cushing syndrome. Smaller eosinophil populations in patients with adrenal Cushing syndrome tend to be correlated with higher levels of blood sugar and glycated hemoglobin. This study suggests that peripheral blood eosinophil composition or count may be associated with serum glucose levels in patients with adrenal Cushing syndrome. Copyright © 2017 Korean Endocrine Society

The Relationship between Pollen Count Levels and Prevalence of Japanese Cedar Pollinosis in Northeast Japan

Directory of Open Access Journals (Sweden)

Kohei Honda

2013-01-01

Conclusions: These results suggest that pollen count levels may correlate with the rate of sensitization for JC pollinosis, but may not affect the rate of onset among sensitized children in northeast Japan.

Digital pulse-shape discrimination applied to an ultra-low-background gas-proportional counting system. First results

International Nuclear Information System (INIS)

Aalseth, C.E.; Day, A.R.; Fuller, E.S.; Hoppe, E.W.; Keillor, M.E.; Mace, E.K.; Myers, A.W.; Overman, C.T.; Panisko, M.E.; Seifert, A.

2013-01-01

A new ultra-low-background proportional counter design was recently developed at Pacific Northwest National Laboratory (PNNL). This design, along with an ultra-low-background counting system which provides passive and active shielding with radon exclusion, has been developed to complement a new shallow underground laboratory (∼30 m water-equivalent) constructed at PNNL. After these steps to mitigate dominant backgrounds (cosmic rays, external gamma-rays, radioactivity in materials), remaining background events do not exclusively arise from ionization of the proportional counter gas. Digital pulse-shape discrimination (PSD) is thus employed to further improve measurement sensitivity. In this work, a template shape is generated for each individual sample measurement of interest, a 'self-calibrating' template. Differences in event topology can also cause differences in pulse shape. In this work, the temporal region analyzed for each event is refined to maximize background discrimination while avoiding unwanted sensitivity to event topology. This digital PSD method is applied to sample and background data, and initial measurement results from a biofuel methane sample are presented in the context of low-background measurements currently being developed. (author)

Low level estimation of 1,4-dioxane in ambient air

International Nuclear Information System (INIS)

Pandit, G.G.; Sahu, S.K.; Puranik, V.D.

2007-05-01

The chemical, 1,4-dioxane does have much relevance with respect to Indian Nuclear Power Programme for counting of Tritium, which is mainly generated during the operation of nuclear research reactors and power reactors which use heavy water. Tritium analysis is routinely carried out at BARC. The scintillation solutions which are used for tritium counting, consist of mainly 1,4 dioxane and naphthalene along with minor concentration of PPO/POPOP. Each sample analysis generates about 10 ml of tritium contaminated spent scintillation liquid waste. Total generation rate of the waste in a typical PHWR reactor is about 2-3 m 3 /year. Controlled incineration of scintillation liquids has been opted at BARC for the treatment of radioactive organic waste. Now that 1,4-dioxane has shown threat to human health and environment, it is important and necessary to know its levels (concentrations) in different environmental compartments to evaluate the risks associated with it. Standard methods are available for the measurement of 1,4-dioxane in air. Higher concentration can be estimated by direct analysis but estimation at lower levels (parts per billion-ppb) requires pre concentration prior to its analysis. Here an improved method that offers increased sensitivity has been used for determining lower levels of 1,4-dioxane. This report presents (1) the development of the methodology for the estimation of 1,4-dioxane at ppb levels using cryogenic pre-concentration and subsequent analysis by Gas Chromatograph with Electron Capture detector (GC-ECD) (2) techniques to check the incineration efficiency and release of 1,4-dioxane to the environment. The data generated by this study could be further used in the evaluation of risk. (author)

sup 9 sup 9 Tc atom counting by quadrupole ICP-MS. Optimisation of the instrumental response

CERN Document Server

Mas, J L; Garcia-Leon, M

2002-01-01

In this paper, an extensive work is done on the specific tune of a conventional ICP-MS for sup 9 sup 9 Tc atom counting. For this, two methods have been used and compared: the partial variable control method and the 5D Simplex method. Instrumental limits of detection of 0.2 and 0.8 ppt, respectively, were obtained. They are noticeably lower than that found with the automatic tune method of the spectrometer, 47 ppt, which shows the need of a specific tune when very low levels of sup 9 sup 9 Tc have to be determined. A study is presented on the mass interferences for sup 9 sup 9 Tc. Our experiments show that the formation of polyatomic atoms or refractory oxides as well as sup 9 sup 8 Mo hydrides seem to be irrelevant for sup 9 sup 9 Tc atom counting. The opposite occurs with the presence of isobaric interferences, i.e. sup 9 sup 9 Ru, and the effect of abundance sensitivity, or low-mass resolution, which can modify the response at m/z=99 to a non-negligible extent.

Stochastic estimation of nuclear level density in the nuclear shell model: An application to parity-dependent level density in 58Ni

Directory of Open Access Journals (Sweden)

Noritaka Shimizu

2016-02-01

Full Text Available We introduce a novel method to obtain level densities in large-scale shell-model calculations. Our method is a stochastic estimation of eigenvalue count based on a shifted Krylov-subspace method, which enables us to obtain level densities of huge Hamiltonian matrices. This framework leads to a successful description of both low-lying spectroscopy and the experimentally observed equilibration of Jπ=2+ and 2− states in 58Ni in a unified manner.

Advances in the sample preparation and the detector for a combined solvent extraction-liquid scintillation method of low-level plutonium measurement

International Nuclear Information System (INIS)

Perdue, P.T.; Christian, D.J.; Thorngate, J.H.; McDowell, W.J.; Case, G.N.

1976-07-01

A combined solvent extraction-liquid scintillation technique, developed at Oak Ridge National Laboratory (ORNL), has many possible applications to the determination of low levels of plutonium and other alpha-emitting nuclides. Using these procedures, plutonium can be extracted from biological or environmental samples and introduced directly into a liquid scintillator. Quenching of the scintillator is thus minimized so that spectroscopic techniques may be employed. Existing chemical procedures and counting equipment were reviewed and improved. Purification of the di(2-ethylhexyl)phosphoric acid (used as the actinide extractant) was found necessary. Destruction of organic material in the sample and control of the valence state of plutonium were found to be major sources of irreproducibility. Methods were developed to allow samples separated with commonly used ion exchange techniques to be extracted into the scintillator. Comparisons were made of a wide variety of the components and parameters of the detector system to find the best combination of pulse-height resolution and pulse-shape discrimination. When a single phototube was used, optimum performance was obtained using a hemispherical reflector-sample holder viewed sideways by an RCA 8575 photomultiplier tube used in conjunction with a special integrating preamplifier and a good quality linear amplifier that used delay lines to shape the pulses

A study of cellular counting to determine minimum thresholds for adequacy for liquid-based cervical cytology using a survey and counting protocol.

Science.gov (United States)

Kitchener, Henry C; Gittins, Matthew; Desai, Mina; Smith, John H F; Cook, Gary; Roberts, Chris; Turnbull, Lesley

2015-03-01

Liquid-based cytology (LBC) for cervical screening would benefit from laboratory practice guidelines that define specimen adequacy for reporting of slides. The evidence base required to define cell adequacy should incorporate both ThinPrep™ (TP; Hologic, Inc., Bedford, MA, USA) and SurePath™ (SP; BD Diagnostics, Burlington, NC, USA), the two LBC systems used in the UK cervical screening programmes. The objectives of this study were to determine (1) current practice for reporting LBC in England, Wales and Scotland, (2) a reproducible method for cell counting, (3) the cellularity of slides classified as inadequate, negative or abnormal and (4) the impact of varying cellularity on the likelihood of detecting cytological abnormalities. The study involved four separate arms to pursue each of the four objectives. (1) A questionnaire survey of laboratories was conducted. (2) A standard counting protocol was developed and used by three experienced cytopathologists to determine a reliable and reproducible cell counting method. (3) Slide sets which included a range of cytological abnormalities were each sent to three laboratories for cell counting to study the correlation between cell counts and reported cytological outcomes. (4) Dilution of LBC samples by fluid only (unmixed) or by dilution with a sample containing normal cells (mixed) was performed to study the impact on reporting of reducing either the total cell count or the relative proportion of abnormal to normal cells. The study was conducted within the cervical screening programmes in England, Wales and Scotland, using routinely obtained cervical screening samples, and in 56 participating NHS cervical cytology laboratories. The study involved only routinely obtained cervical screening samples. There was no clinical intervention. The main outcome measures were (1) reliability of counting method, (2) correlation of reported cytology grades with cellularity and (3) levels of detection of abnormal cells in

SPERM COUNT DISTRIBUTIONS IN FERTILE MEN

Science.gov (United States)

Sperm concentration and count are often used as indicators of environmental impacts on male reproductive health. Existing clinical databases may be biased towards subfertile men with low sperm counts and less is known about expected sperm count distributions in cohorts of fertil...

Epidemiological methods of assessing risks from low level occupational exposure to ionising radiation

International Nuclear Information System (INIS)

Reissland, J.A.

1982-01-01

The resolution of radiation-attributable malignancies from the background of malignancies which are responsible for about 20% of all deaths in the Western world, presents a formidable challenge to epidemiological methods. Some of the major difficulties facing those with the task of estimating the risks associated with exposure to low level ionising radiation are discussed, particularly in the context of radiological protection. Some of the studies currently in progress are summarised and suggestions are made for other work which may help to contribute to a better understanding of the quantitative aspects of radiation risk assessment. (author)

Monitoring Milk Somatic Cell Counts

Directory of Open Access Journals (Sweden)

Gheorghe Şteţca

2014-11-01

Full Text Available The presence of somatic cells in milk is a widely disputed issue in milk production sector. The somatic cell counts in raw milk are a marker for the specific cow diseases such as mastitis or swollen udder. The high level of somatic cells causes physical and chemical changes to milk composition and nutritional value, and as well to milk products. Also, the mastitic milk is not proper for human consumption due to its contribution to spreading of certain diseases and food poisoning. According to these effects, EU Regulations established the maximum threshold of admitted somatic cells in raw milk to 400000 cells / mL starting with 2014. The purpose of this study was carried out in order to examine the raw milk samples provided from small farms, industrial type farms and milk processing units. There are several ways to count somatic cells in milk but the reference accepted method is the microscopic method described by the SR EN ISO 13366-1/2008. Generally samples registered values in accordance with the admissible limit. By periodical monitoring of the somatic cell count, certain technological process issues are being avoided and consumer’s health ensured.

Musculoskeletal imaging with a prototype photon-counting detector.

Science.gov (United States)

Gruber, M; Homolka, P; Chmeissani, M; Uffmann, M; Pretterklieber, M; Kainberger, F

2012-01-01

To test a digital imaging X-ray device based on the direct capture of X-ray photons with pixel detectors, which are coupled with photon-counting readout electronics. The chip consists of a matrix of 256 × 256 pixels with a pixel pitch of 55 μm. A monolithic image of 11.2 cm × 7 cm was obtained by the consecutive displacement approach. Images of embalmed anatomical specimens of eight human hands were obtained at four different dose levels (skin dose 2.4, 6, 12, 25 μGy) with the new detector, as well as with a flat-panel detector. The overall rating scores for the evaluated anatomical regions ranged from 5.23 at the lowest dose level, 6.32 at approximately 6 μGy, 6.70 at 12 μGy, to 6.99 at the highest dose level with the photon-counting system. The corresponding rating scores for the flat-panel detector were 3.84, 5.39, 6.64, and 7.34. When images obtained at the same dose were compared, the new system outperformed the conventional DR system at the two lowest dose levels. At the higher dose levels, there were no significant differences between the two systems. The photon-counting detector has great potential to obtain musculoskeletal images of excellent quality at very low dose levels.

Short Communication: A Simple Method for Performing Worm-Egg Counts on Sodium Acetate Formaldehyde-Preserved Samples

Directory of Open Access Journals (Sweden)

Wayne Melrose

2012-01-01

Full Text Available The Kato Katz method is the most common way of performing worm-egg counts on human faecal samples, but it must be done in the field using freshly collected samples. This makes it difficult to use in remote, poorly accessible situations. This paper describes a simple method for egg counts on preserved samples collected in the field and sent to a central location for further processing.

Examination of background contamination levels for gas counting and AMS target preparation in Trondheim

DEFF Research Database (Denmark)

Gulliksen, S.; Thomsen, M.S.

1992-01-01

conventional gas proportional counting (GPC) system. We have also studied contamination levels of our target preparation for C-14 accelerator mass spectrometry (AMS) dating in Uppsala. A significant lower background is obtained for Icelandic double spar than for marbles, probably due to a crystal structure...

Low-level waste management

International Nuclear Information System (INIS)

Levin, G.B.

1980-01-01

An overview of the current situation in the United States and a look to the future of low-level waste management are presented. Current problems and challenges are discussed, such as: the need of additional disposal sites in the future; risks and costs involved in transport of low-level wastes; reduction of low-level waste volume through smelting, incineration, and storage for wastes containing nuclides with short half lives; development of a national policy for the management of low-level waste, and its implementation through a sensible system of regulations. Establishing a success with low-level waste management should provide the momentum and public confidence needed to continue on and to resolve the technical and politically more difficult low-level waste problems

An corrective method to correct of the inherent flaw of the asynchronization direct counting circuit

International Nuclear Information System (INIS)

Wang Renfei; Liu Congzhan; Jin Yongjie; Zhang Zhi; Li Yanguo

2003-01-01

As a inherent flaw of the Asynchronization Direct Counting Circuit, the crosstalk, which is resulted from the randomicity of the time-signal always exists between two adjacent channels. In order to reduce the counting error derived from the crosstalk, the author propose an effective method to correct the flaw after analysing the mechanism of the crosstalk

Vitrification of low-level and mixed wastes

International Nuclear Information System (INIS)

Johnson, T.R.; Bates, J.K.; Feng, Xiangdong.

1994-01-01

The US Department of Energy (DOE) and nuclear utilities have large quantities of low-level and mixed wastes that must be treated to meet repository performance requirements, which are likely to become even more stringent. The DOE is developing cost-effective vitrification methods for producing durable waste forms. However, vitrification processes for high-level wastes are not applicable to commercial low-level wastes containing large quantities of metals and small amounts of fluxes. New vitrified waste formulations are needed that are durable when buried in surface repositories

Low-level radioactive waste, mixed low-level radioactive waste, and biomedical mixed waste

International Nuclear Information System (INIS)

Anon.

1994-01-01

This document describes the proceedings of a workshop entitled: Low-Level Radioactive Waste, Mixed Low-Level Radioactive Waste, and Biomedical Mixed Waste presented by the National Low-Level Waste Management Program at the University of Florida, October 17-19, 1994. The topics covered during the workshop include technical data and practical information regarding the generation, handling, storage and disposal of low-level radioactive and mixed wastes. A description of low-level radioactive waste activities in the United States and the regional compacts is presented

Radioactivity evaluation method for pre-packed concrete packages of low-level dry active wastes

International Nuclear Information System (INIS)

Sakai, Toshiaki; Funahashi, Tetsuo; Watabe, Kiyomi; Ozawa, Yukitoshi; Kashiwagi, Makoto

1998-01-01

Low-level dry active wastes of nuclear power plants are grouted with cement mortal in a container and planned to disposed into the shallow land disposal site. The characteristics of radionuclides contained in dry active wastes are same as homogeneous solidified wastes. In the previous report, we reported the applicability of the radioactivity evaluation methods established for homogeneous solidified wastes to pre-packed concrete packages. This report outlines the developed radioactivity evaluation methods for pre-packed concrete packages based upon recent data. Since the characteristics of dry active wastes depend upon the plant system in which dry active wastes originate and the types of contamination, sampling of wastes and activity measurement were executed to derive scaling factors. The radioactivity measurement methods were also verified. The applicability of non-destructive methods to measure radioactivity concentration of pre-packed concrete packages was examined by computer simulation. It is concluded that those methods are accurate enough to measure actual waste packages. (author)

Performance of 2000CA/LL and 2260XL liquid scintillation spectrometers for low-level tritium and carbon-14 analyses

International Nuclear Information System (INIS)

Rozanski, K.; Stichler, W.; Schwarz, P.

1991-01-01

The performance of two commercially available liquid scintillation spectrometers for low-level counting of 3 H and 14 C has been investigated. Two models of new technology Tri-Carb spectrometers from the Packard Instrument Company were tested: the 2000CA/LL and 2260XL. The measurements revealed a superior 3 H performance of the 2000CA/LL equipment owing to its substantially higher counting efficiency. Results for 14 C are less conclusive and depend on the configuration of the counting parameters selected. A comparison of three commercially available scintillation cocktails for tritium assay in water samples revealed a superior performance for PicoFluor LLT. (Author)

High throughput octal alpha/gamma spectrometer for low level bioassay estimations

International Nuclear Information System (INIS)

Bhasin, B.D.; Shirke, S.H.; Suri, M.M.; Vaidya, P.P.; Ghodgaonkar, M.D.

1995-01-01

The present paper describes the development of a high throughput octal alpha spectrometry system specially developed for the estimation of low levels of actinides in bioassay and environmental samples. The system processes simultaneously the outputs coming from eight independent detectors. It can be configured to simultaneously record low level alpha and gamma spectra. The high throughput is achieved by using a prioritised multiplexer router. The prioritised multiplexing and routing coupled with fast 8K ADC (conversion time 20 μsec) allow simultaneous acquisition of multiple spectra without any significant loss in counts. The dual (8K, 24bit) port memory facilitates easy online viewing of spectrum buildup. A menu driven user friendly software makes the operating system convenient to use. A specially developed software provides built-in routines for processing the spectra and estimating the isotopic activity. The interactive mode of software provides easy identification of isotopes compatible with the separation chemistry of different actinides. (author). 6 refs., 2 figs

Low radioactivities '85. (The 7th Nuclear Science Colloquium)

International Nuclear Information System (INIS)

1985-01-01

The conference proceedings contain 108 papers. The following topics are dealt with: accelerator mass spectroscopy, rare decays, underground laboratories, low level counting and spectroscopy, double beta-decay experiments, low level detectors, cosmogenic radionuclides and rare events, 14 C counting and applications, 3 H counting and hydrology appllications, natural radioactivity in the environment, gaseous detectors, anthropogenic radionuclides and radioactivity in the environment. (J.P.)

K-edge energy-based calibration method for photon counting detectors

Science.gov (United States)

Ge, Yongshuai; Ji, Xu; Zhang, Ran; Li, Ke; Chen, Guang-Hong

2018-01-01

In recent years, potential applications of energy-resolved photon counting detectors (PCDs) in the x-ray medical imaging field have been actively investigated. Unlike conventional x-ray energy integration detectors, PCDs count the number of incident x-ray photons within certain energy windows. For PCDs, the interactions between x-ray photons and photoconductor generate electronic voltage pulse signals. The pulse height of each signal is proportional to the energy of the incident photons. By comparing the pulse height with the preset energy threshold values, x-ray photons with specific energies are recorded and sorted into different energy bins. To quantitatively understand the meaning of the energy threshold values, and thus to assign an absolute energy value to each energy bin, energy calibration is needed to establish the quantitative relationship between the threshold values and the corresponding effective photon energies. In practice, the energy calibration is not always easy, due to the lack of well-calibrated energy references for the working energy range of the PCDs. In this paper, a new method was developed to use the precise knowledge of the characteristic K-edge energy of materials to perform energy calibration. The proposed method was demonstrated using experimental data acquired from three K-edge materials (viz., iodine, gadolinium, and gold) on two different PCDs (Hydra and Flite, XCounter, Sweden). Finally, the proposed energy calibration method was further validated using a radioactive isotope (Am-241) with a known decay energy spectrum.

Differential measurement of low level HTO and HT leak rates

International Nuclear Information System (INIS)

Sheehan, W.E.; Muldoon, K.M.

1976-08-01

Leak rates of 5 x 10 -17 cm 3 /sec and greater can be measured by a very simple technique that will also differentiate tritium oxide (HTO) from tritium gas (HT). Because of the much greater health hazard of tritium oxide (200 to 1), the determination of chemical form is significant. The method involves flushing a gas collection chamber, containing the item being measured, with dry air. The flushed air is passed through an ethylene glycol bubbler which removes only the HTO. The outlet of the ethylene glycol bubbler is connected to a heated (400 0 C) palladium sponge catalyst which converts the HT to HTO and then to a second ethylene glycol bubbler for collection of the oxidized tritium gas. Liquid scintillation (p-dioxane base) counting solution is added directly to the bubblers and counted for tritium in a Liquid Scintillation Spectrometer. Advantages, method validation, operational experience, and data obtained by this technique are discussed. The sensitivity of the method is dependent on the time allowed between bubbler changes, the liquid scintillation spectrometer counting efficiency, background, and counting times employed

Disseminated HIV-Associated Kaposi’s Sarcoma With High CD4 Cell Count And Low Viral Load

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Diana Pereira Anjos

2017-12-01

Full Text Available Kaposi’s sarcoma is considered an acquired immunodeficiency syndrome-defining illness and is caused by human herpesvirus 8. It has been associated with patients infected with human immunodeficiency virus (HIV who have CD4 T lymphocytes <200 cells/uL and high viral loads. We report a case of a 23-year old woman infected with HIV-1 and receiving antiretroviral treatment since diagnosis, with high CD4 cell count and low viral load that presented with disseminated Kaposi’s sarcoma. Clinicians should be aware of the occurrence of Kaposi’s sarcoma despite robust CD4 cell counts.

Total lymphocyte count as a substitute to cd4 count in management of hiv infected individuals in resource limited society

International Nuclear Information System (INIS)

Daud, M.Y.; Qazi, R.A.

2015-01-01

Pakistan is a resource limited society and gold standard parameters to monitor HIV disease activity are very costly. The objective of the study was to evaluate total lymphocyte count (TLC) as a surrogate to CD4 count to monitor disease activity in HIV/AIDS in resource limited society. Methods: This cross sectional study was carried out at HIV/AIDS treatment centre, Pakistan Institute of Medical Sciences (PIMS), Islamabad. A total of seven hundred and seventy four (774) HIV positive patients were enrolled in this study, and their CD4 count and total lymphocyte count were checked to find any correlation between the two by using Spearman ranked correlation coefficient. Results: The mean CD4 count was (434.30 ± 269.23), with minimum CD4 count of (9.00), and maximum of (1974.00). The mean total lymphocyte count (TLC) was (6764.0052 ± 2364.02) with minimum TLC (1200.00) and maximum TLC was (20200.00). Using the Pearson's correlation (r) there was a significant and positive correlation between TLC and CD4 count. (r2=0.127 and p=0.000) at 0.01 level. Conclusion: Our study showed a significant positive correlation between CD4 count and total lymphocyte count (TLC), so TLC can be used as a marker of disease activity in HIV infected patients. (author)

Meningiomas: Objective assessment of proliferative indices by immunohistochemistry and automated counting method.

Science.gov (United States)

Chavali, Pooja; Uppin, Megha S; Uppin, Shantveer G; Challa, Sundaram

2017-01-01

The most reliable histological correlate of recurrence risk in meningiomas is increased mitotic activity. Proliferative index with Ki-67 immunostaining is a helpful adjunct to manual counting. However, both show considerable inter-observer variability. A new immunohistochemical method for counting mitotic figures, using antibody against the phosphohistone H3 (PHH3) protein was introduced. Similarly, a computer based automated counting for Ki-67 labelling index (LI) is available. To study the use of these new techniques in the objective assessment of proliferation indices in meningiomas. This was a retrospective study of intracranial meningiomas diagnosed during the year 2013.The hematoxylin and eosin (H and E) sections and immunohistochemistry (IHC) with Ki-67 were reviewed by two pathologists. Photomicrographs of the representative areas were subjected to Ki-67 analysis by Immunoratio (IR) software. Mean Ki-67 LI, both manual and by IR were calculated. IHC with PHH3 was performed. PHH3 positive nuclei were counted and mean values calculated. Data analysis was done using SPSS software. A total of 64 intracranial meningiomas were diagnosed. Evaluation on H and E, PHH3, Ki-67 LI (both manual and IR) were done in 32 cases (22 grade I and 10 grade II meningiomas). Statistically significant correlation was seen between the mitotic count in each grade and PHH3 values and also between the grade of the tumor and values of Ki-67 and PHH3. Both the techniques used in the study had advantage over, as well as, correlated well with the existing techniques and hence, can be applied to routine use.

Method and system of simulating nuclear power plant count rate for training purposes

International Nuclear Information System (INIS)

Alliston, W.H.; Koenig, R.H.

1975-01-01

A method and system are described for the real-time simulation of the dynamic operation of a nuclear power plant in which nuclear flux rate counters are provided for monitoring the rate of nuclear fission of the reactor. The system utilizes apparatus that includes digital computer means for calculating data relating to the rate of nuclear fission of a simulated reactor model, which rate is controlled in accordance with the operation of control panel devices. A digital number from the computer corresponding to the flux rate controls an oscillator driven counter means to produce a pulse after a predetermined count. This pulse controls an oscillator driven polynomial counter to count a random number that controls a third counter in accordance with pulse from the first counter to produce a random fission count for operating the meters. (U.S.)

Restoring Cytokine Balance in HIV-Positive Individuals with Low CD4 T Cell Counts

Science.gov (United States)

Valdivia, Anddre; Ly, Judy; Gonzalez, Leslie; Hussain, Parveen; Saing, Tommy; Islamoglu, Hicret; Pearce, Daniel; Ochoa, Cesar

2017-01-01

Abstract HIV infects and destroys CD4+ T cells leading to a compromised immune system. In a double-blinded study, a group of HIV-infected individuals with CD4+ T cell counts below 350 cells/mm3 were given either an empty liposomal supplement or a liposomal glutathione (L-GSH) supplement to take over a 3-month period. Baseline measurements in HIV-positive subjects show a significant decrease in levels of interleukin (IL)-12, IL-2, and interferon (IFN)-γ, along with a substantial increase in the levels of IL-6, IL-10, transforming growth factor (TGF)-β, and free radicals, compared to healthy individuals. Supplementation of HIV-positive subjects with L-GSH for 3 months resulted in a notable increase in the levels of IL-12, IL-2, and IFN-γ, with a concomitant decrease in the levels of IL-6, IL-10, and free radicals, and stabilization in the levels of TGF-β, IL-1, and IL-17, compared to their placebo counterparts. Levels of free radicals in CD4+ T cells stabilized, while GSH levels increased in the treatment group. Those in the placebo group showed no significant difference throughout the study. In summary, supplementation with L-GSH in HIV-infected individuals with CD4+ T cell counts below 350 cells/mm3 can help restore redox homeostasis and cytokine balance, therefore aiding the immune system to control opportunistic infections. PMID:28398068

Is automated platelet counting still a problem in thrombocytopenic blood?

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Raimundo Antônio Gomes Oliveira

Full Text Available CONTEXT: Reliable platelet counting is crucial for indicating prophylactic platelet transfusion in thrombocytopenic patients. OBJECTIVE: To evaluate the precision and accuracy of platelet counting for thrombocytopenic patients, using four different automated counters in comparison with the Brecher & Cronkite reference method recommended by the International Committee for Standardization in Hematology (ICSH. TYPE OF STUDY: Automated platelet counting assessment in thrombocytopenic patients. SETTING: Hematology Laboratory, Hospital do Servidor Público Estadual de São Paulo, and the Hematology Division of Instituto Adolfo Lutz, São Paulo, SP, Brazil. MAIN MEASUREMENTS: Brecher & Cronkite reference method and four different automated platelet counters. PARTICIPANTS: 43 thrombocytopenic patients with platelet counts of less than 30,000/µl RESULTS: The ADVIA-120 (Bayer, Coulter STKS, H1 System (Technicom-Bayer and Coulter T-890 automatic instruments presented great precision and accuracy in relation to laboratory thrombocytopenic samples obtained by diluting blood from normal donors. However, when thrombocytopenic patients were investigated, all the counters except ADVIA (which is based on volume and refraction index showed low accuracy when compared to the Brecher & Cronkite reference method (ICSH. The ADVIA counter showed high correlation (r = 0.947. However, all counters showed flags in thrombocytopenic samples. CONCLUSION: The Brecher & Cronkite reference method should always be indicated in thrombocytopenic patients for platelet counts below 30,000 plt /µl obtained in one dimensional counters.

Determining Gate Count Reliability in a Library Setting

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Jeffrey Phillips

2016-09-01

Full Text Available Objective – Patron counts are a common form of measurement for library assessment. To develop accurate library statistics, it is necessary to determine any differences between various counting devices. A yearlong comparison between card reader turnstiles and laser gate counters in a university library sought to offer a standard percentage of variance and provide suggestions to increase the precision of counts. Methods – The collection of library exit counts identified the differences between turnstile and laser gate counter data. Statistical software helped to eliminate any inaccuracies in the collection of turnstile data, allowing this data set to be the base for comparison. Collection intervals were randomly determined and demonstrated periods of slow, average, and heavy traffic. Results – After analyzing 1,039,766 patron visits throughout a year, the final totals only showed a difference of .43% (.0043 between the two devices. The majority of collection periods did not exceed a difference of 3% between the counting instruments. Conclusion – Turnstiles card readers and laser gate counters provide similar levels of reliability when measuring patron activity. Each system has potential counting inaccuracies, but several methods exist to create more precise totals. Turnstile card readers are capable of offering greater detail involving patron identity, but their high cost makes them inaccessible for libraries with lower budgets. This makes laser gate counters an affordable alternative for reliable patron counting in an academic library.

A gamma camera count rate saturation correction method for whole-body planar imaging

Science.gov (United States)

Hobbs, Robert F.; Baechler, Sébastien; Senthamizhchelvan, Srinivasan; Prideaux, Andrew R.; Esaias, Caroline E.; Reinhardt, Melvin; Frey, Eric C.; Loeb, David M.; Sgouros, George

2010-02-01

Whole-body (WB) planar imaging has long been one of the staple methods of dosimetry, and its quantification has been formalized by the MIRD Committee in pamphlet no 16. One of the issues not specifically addressed in the formalism occurs when the count rates reaching the detector are sufficiently high to result in camera count saturation. Camera dead-time effects have been extensively studied, but all of the developed correction methods assume static acquisitions. However, during WB planar (sweep) imaging, a variable amount of imaged activity exists in the detector's field of view as a function of time and therefore the camera saturation is time dependent. A new time-dependent algorithm was developed to correct for dead-time effects during WB planar acquisitions that accounts for relative motion between detector heads and imaged object. Static camera dead-time parameters were acquired by imaging decaying activity in a phantom and obtaining a saturation curve. Using these parameters, an iterative algorithm akin to Newton's method was developed, which takes into account the variable count rate seen by the detector as a function of time. The algorithm was tested on simulated data as well as on a whole-body scan of high activity Samarium-153 in an ellipsoid phantom. A complete set of parameters from unsaturated phantom data necessary for count rate to activity conversion was also obtained, including build-up and attenuation coefficients, in order to convert corrected count rate values to activity. The algorithm proved successful in accounting for motion- and time-dependent saturation effects in both the simulated and measured data and converged to any desired degree of precision. The clearance half-life calculated from the ellipsoid phantom data was calculated to be 45.1 h after dead-time correction and 51.4 h with no correction; the physical decay half-life of Samarium-153 is 46.3 h. Accurate WB planar dosimetry of high activities relies on successfully compensating

Study on radon and thoron progeny levels in Gudalore in South India

International Nuclear Information System (INIS)

Selvasekarapandian, S.; Sivakumar, R.; Mugunthamanikandan, N.; Meenakshisundaram, V.; Santhanam, R.

2000-01-01

One of the important route of radiation exposure to man is through inhalation of air containing radioisotopes. A major contribution to inhalation dose comes from radon, thoron and its progenies. The indoor radon and thoron progeny levels are determined by two count method. In this method the radon and thoron progenies are collected on a glass fiber filter paper using volume air sampler (Staplex) and counted for alpha activity in ZnS (Ag) alpha counting system. It is observed that thoron working level is higher than the radon working level in all houses except few houses with stone walls and mosaic floor. Behavior of indoor radon and thoron working levels for different seasons at different houses are determined and discussed in detail. Radon and thoron working levels are measured high in winter, autumn, and low in summer and rainy seasons. Among all seasons highest value is measured in winter and low in summer and rainy seasons. Radon progeny working level varies from 1.659 to 6.675 mWL, whereas thoron progeny working level varies from 1.670 to 12.671 mWL. The geometric mean values of radon and thoron progeny concentration in the present study are 2.836 and 4.133 mWL. The high thoron progeny level observed in this is attributed to the high thorium content observed in soils of this area. (author)

Tritium activity in milk by liquid scintillation counting

International Nuclear Information System (INIS)

Zheng Huang

1993-01-01

This paper estimates the total tritium content of both the organic and aqueous fractions simultaneously. To fulfill these conditions, the chosen scintillator should be able to accept large sample loadings and display the same counting efficiency for the organic as well as aqueous fractions of the whole milk. In an attempt to establish this method, samples from four different brands of milk were analysed using the pseudocumence based Picofluor 30 (Canberra Packard) and the di-isopropyl naphthalene based Aquasafe 500 (Zinser Analytic) scintillator solution. Glass vials were used thus enabling visual observation to be made. The tritium activities of four different brands of milks were estimated to be very low and at, or near, the detection level of the system

Pressure-based impact method to count bedload particles

Science.gov (United States)

Antico, Federica; Mendes, Luís; Aleixo, Rui; Ferreira, Rui M. L.

2017-04-01

-channel flow, was analysed. All tests featured a period of 90 s data collection. For a detailed description of the laboratory facilities and test conditions see Mendes et al. (2016). Results from MiCas system were compared with those of obtained from the analysis of a high-speed video footage. The obtained results shown a good agreement between both techniques. The measurements carried out allowed to determine that MiCas system is able to track particle impact in real-time within an error margin of 2.0%. From different tests with the same conditions it was possible to determine the repeatability of MiCas system. Derived quantities such as bedload transport rates, eulerian auto-correlation functions and structure functions are also in close agreement with measurements based on optical methods. The main advantages of MiCas system relatively to digital image processing methods are: a) independence from optical access, thus avoiding problems with light intensity variations and oscillating free surfaces; b) small volume of data associated to particle counting, which allows for the possibility of acquiring very long data series (hours, days) of particle impacts. In the considered cases, it would take more than two hours to generate 1 MB of data. For the current validation tests, 90 s acquisition time generated 25 Gb of images but 11 kB of MiCas data. On the other hand the time necessary to process the digital images may correspond to days, effectively limiting its usage to small time series. c) the possibility of real-time measurements, allowing for detection of problems during the experiments and minimizing some post-processing steps. This research was partially supported by Portuguese and European funds, within programs COMPETE2020 and PORL-FEDER, through project PTDC/ECM-HID/6387/2014 granted by the National Foundation for Science and Technology (FCT). References Mendes L., Antico F., Sanches P., Alegria F., Aleixo R., and Ferreira RML. (2016). A particle counting system for

Low serum albumin and total lymphocyte count as predictors of 30 day hospital readmission in patients 65 years of age or older

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Robert Robinson

2015-08-01

Full Text Available Introduction. Hospital readmission within 30 days of discharge is a target for health care cost savings through the medicare Value Based Purchasing initiative. Because of this focus, hospitals and health systems are investing considerable resources into the identification of patients at risk of hospital readmission and designing interventions to reduce the rate of hospital readmission. Malnutrition is a known risk factor for hospital readmission.Materials and Methods. All medical patients 65 years of age or older discharged from Memorial Medical Center from January 1, 2012 to March 31, 2012 who had a determination of serum albumin level and total lymphocyte count on hospital admission were studied retrospectively. Admission serum albumin levels and total lymphocyte counts were used to classify the nutritional status of all patients in the study. Patients with a serum albumin less than 3.5 grams/dL and/or a TLC less than 1,500 cells per mm3 were classified as having protein energy malnutrition. The primary outcome investigated in this study was hospital readmission for any reason within 30 days of discharge.Results. The study population included 1,683 hospital discharges with an average age of 79 years. The majority of the patients were female (55.9% and had a DRG weight of 1.22 (0.68. 219 patients (13% were readmitted within 30 days of hospital discharge. Protein energy malnutrition was common in this population. Low albumin was found in 973 (58% patients and a low TLC was found in 1,152 (68% patients. Low albumin and low TLC was found in 709 (42% of patients. Kaplan–Meier analysis shows any laboratory evidence of PEM is a significant (p < 0.001 predictor of hospital readmission. Low serum albumin (p < 0.001 and TLC (p = 0.018 show similar trends. Cox proportional-hazards regression analysis showed low serum albumin (Hazard Ratio 3.27, 95% CI [2.30–4.63] and higher DRG weight (Hazard Ratio 1.19, 95% CI [1.03–1.38] to be significant

Statistical Methods for Unusual Count Data: Examples From Studies of Microchimerism

Science.gov (United States)

Guthrie, Katherine A.; Gammill, Hilary S.; Kamper-Jørgensen, Mads; Tjønneland, Anne; Gadi, Vijayakrishna K.; Nelson, J. Lee; Leisenring, Wendy

2016-01-01

Natural acquisition of small amounts of foreign cells or DNA, referred to as microchimerism, occurs primarily through maternal-fetal exchange during pregnancy. Microchimerism can persist long-term and has been associated with both beneficial and adverse human health outcomes. Quantitative microchimerism data present challenges for statistical analysis, including a skewed distribution, excess zero values, and occasional large values. Methods for comparing microchimerism levels across groups while controlling for covariates are not well established. We compared statistical models for quantitative microchimerism values, applied to simulated data sets and 2 observed data sets, to make recommendations for analytic practice. Modeling the level of quantitative microchimerism as a rate via Poisson or negative binomial model with the rate of detection defined as a count of microchimerism genome equivalents per total cell equivalents tested utilizes all available data and facilitates a comparison of rates between groups. We found that both the marginalized zero-inflated Poisson model and the negative binomial model can provide unbiased and consistent estimates of the overall association of exposure or study group with microchimerism detection rates. The negative binomial model remains the more accessible of these 2 approaches; thus, we conclude that the negative binomial model may be most appropriate for analyzing quantitative microchimerism data. PMID:27769989

Tutorial on X-ray photon counting detector characterization.

Science.gov (United States)

Ren, Liqiang; Zheng, Bin; Liu, Hong

2018-01-01

Recent advances in photon counting detection technology have led to significant research interest in X-ray imaging. As a tutorial level review, this paper covers a wide range of aspects related to X-ray photon counting detector characterization. The tutorial begins with a detailed description of the working principle and operating modes of a pixelated X-ray photon counting detector with basic architecture and detection mechanism. Currently available methods and techniques for charactering major aspects including energy response, noise floor, energy resolution, count rate performance (detector efficiency), and charge sharing effect of photon counting detectors are comprehensively reviewed. Other characterization aspects such as point spread function (PSF), line spread function (LSF), contrast transfer function (CTF), modulation transfer function (MTF), noise power spectrum (NPS), detective quantum efficiency (DQE), bias voltage, radiation damage, and polarization effect are also remarked. A cadmium telluride (CdTe) pixelated photon counting detector is employed for part of the characterization demonstration and the results are presented. This review can serve as a tutorial for X-ray imaging researchers and investigators to understand, operate, characterize, and optimize photon counting detectors for a variety of applications.

Analysis of low-marbled Hanwoo cow meat aged with different dry-aging methods

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Hyun Jung Lee

2017-12-01

Full Text Available Objective Different dry-aging methods [traditional dry-aging (TD, simplified dry-aging (SD, and SD in an aging bag (SDB] were compared to investigate the possible use of SD and/or SDB in practical situations. Methods Sirloins from 48 Hanwoo cows were frozen (Control, 2 days postmortem or dry-aged for 28 days using the different aging methods and analyzed for chemical composition, total aerobic bacterial count, shear force, inosine 5′-monophosphate (IMP and free amino acid content, and sensory properties. Results The difference in chemical composition, total aerobic bacterial count, shear force, IMP, and total free amino acid content were negligible among the 3 dry-aged groups. The SD and SDB showed statistically similar tenderness, flavor, and overall acceptability relative to TD. However, SDB had a relatively higher saleable yield. Conclusion Both SD and SDB can successfully substitute for TD. However, SDB would be the best option for simplified dry-aging of low-marbled beef with a relatively high saleable yield.

Analysis of electroperforated materials using the quadrat counts method

Energy Technology Data Exchange (ETDEWEB)

Miranda, E; Garzon, C; Garcia-Garcia, J [Departament d' Enginyeria Electronica, Universitat Autonoma de Barcelona, 08193 Bellaterra, Barcelona (Spain); MartInez-Cisneros, C; Alonso, J, E-mail: enrique.miranda@uab.cat [Departament de Quimica AnalItica, Universitat Autonoma de Barcelona, 08193 Bellaterra, Barcelona (Spain)

2011-06-23

The electroperforation distribution in thin porous materials is investigated using the quadrat counts method (QCM), a classical statistical technique aimed to evaluate the deviation from complete spatial randomness (CSR). Perforations are created by means of electrical discharges generated by needle-like tungsten electrodes. The objective of perforating a thin porous material is to enhance its air permeability, a critical issue in many industrial applications involving paper, plastics, textiles, etc. Using image analysis techniques and specialized statistical software it is shown that the perforation locations follow, beyond a certain length scale, a homogeneous 2D Poisson distribution.

New three-count technique for short-lived radon decay products in air

International Nuclear Information System (INIS)

Tian Deyuan; Lu Zhizhao

1998-01-01

Up to the present, radon and its short-lived decay products in air are usually monitored by means of a detection. But radon progeny, including RaB ( 214 Pb) and RaC ( 214 Bi) which are β and γ emitters, contribute about 90% to the equilibrium equivalent radon concentration (EECRn). Therefore, this paper introduces a new three-count technique by a β detector in the light of radioactive decay law and its boundary conditions during sampling and counting times to solve the Bateman equation. β (even low level β) instruments have been fairly popularized domestically and internationally. It can be used not only as an instrument for radon and its daughters in air, but also as a monitor for β airborne activity in the environment. This new method taps further the latent power of the present instrument and realizes various uses for a unit. (author)

Clinical significance of measurement of changes of serum IL-2, SIL-2R, TNF-α levels, B lymphocyte count and T subsets distribution type after treatment in patients with vitiligo

International Nuclear Information System (INIS)

Xie Chuntao

2007-01-01

Objective: To study the changes of serum IL-2, SIL-2R, TNF-α levels B lymphocytes count and T lyonphocyte subsets distribation type after treatment in patients with vitiligo. Methods: Serum IL-2, TNF-α (with RIA), SIL-2R (with ELISA) levels, B lymphocytes count and T subsets (with monoclonal antibody technique) were examined in 40 patients with vitiligo both before and after treatment as well as in 35 controls. Results: Before treatment, serum SIL-2R, TNF-α levels and B lymphocytes count were significantly higher than those in controls (P<0.01), while the serum IL-2, CD3, CD4 levels CD4/CD8 ratio were significantly lower(P<0.01). After treatment for 6 months, the data were greatly corrected but remanied significantly different from those in controls (P<0.05). Conclusion: Vitiligo is a kind of auto-immune diseases with abnormal immuno-regulation. (authors)

Effect of a 21-day balneotherapy program on blood cell counts, ponogen levels, and blood biochemical indexes in servicemen in sub-health condition.

Science.gov (United States)

Xu, Li; Wu, Lin; Liu, Tingting; Xing, Wenrong; Cao, Xinsheng; Zhang, Shu; Su, Zongyi

2017-09-01

[Purpose] The aim of our study was to explore the changes in the blood of servicemen in sub-health conditions during a 21-day balneotherapy program. [Subjects and Methods] For this study, 129 servicemen in sub-health condition were recruited. The subjects were randomly divided into either the balneotherapy group (70) or the control group (59). Subjects in the balneotherapy group received whole-body immersion bath therapy in thermomineral water (30 min daily) for 21 days. Their blood samples were examined 1 day before and after balneotherapy. The parameters studied included mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), white blood cell (WBC), lactic acid (LAC), alanine aminotransferase (ALT), glucose (GLU), and triglycerides (TG) levels. [Results] After 21 days of balneotherapy, MCH levels and MCHC increased significantly and WBC counts increased significantly. LAC levels decreased significantly. ALT, GLU, and TG levels decreased significantly. In the control group, there were no statistical differences before and after tap water baths following the same procedure. [Conclusion] A 21-day balneotherapy program significantly improved blood cell counts and blood biochemical indexes and reduced ponogen levels in servicemen in sub-health condition.

Bacteriocidal activity of sanitizers against Enterococcus faecium attached to stainless steel as determined by plate count and impedance methods.

Science.gov (United States)

Andrade, N J; Bridgeman, T A; Zottola, E A

1998-07-01

Enterococcus faecium attached to stainless steel chips (100 mm2) was treated with the following sanitizers: sodium hypochlorite, peracetic acid (PA), peracetic acid plus an organic acid (PAS), quaternary ammonium, organic acid, and anionic acid. The effectiveness of sanitizer solutions on planktonic cells (not attached) was evaluated by the Association of Official Analytical Chemists (AOAC) suspension test. The number of attached cells was determined by impedance measurement and plate count method after vortexing. The decimal reduction (DR) in numbers of the E. faecium population was determined for the three methods and was analyzed by analysis of variance (P plate count method after vortexing, and impedance measurement, respectively. Plate count and impedance methods showed a difference (P measurement was the best method to measure adherent cells. Impedance measurement required the development of a quadratic regression. The equation developed from 82 samples is as follows: log CFU/chip = 0.2385T2-0.96T + 9.35, r2 = 0.92, P plate count method after vortexing. These data suggest that impedance measurement is the method of choice when evaluating the number of bacterial cells adhered to a surface.

Sampling and Pooling Methods for Capturing Herd Level Antibiotic Resistance in Swine Feces using qPCR and CFU Approaches

DEFF Research Database (Denmark)

Schmidt, Gunilla Veslemøy; Mellerup, Anders; Christiansen, Lasse Engbo

2015-01-01

The aim of this article was to define the sampling level and method combination that captures antibiotic resistance at pig herd level utilizing qPCR antibiotic resistance gene quantification and culture-based quantification of antibiotic resistant coliform indicator bacteria. Fourteen qPCR assays...... for commonly detected antibiotic resistance genes were developed, and used to quantify antibiotic resistance genes in total DNA from swine fecal samples that were obtained using different sampling and pooling methods. In parallel, the number of antibiotic resistant coliform indicator bacteria was determined...... when comparing individual sampling and pooling methods. qPCR on pooled samples was found to be a good representative for the general resistance level in a pig herd compared to the coliform CFU counts. It had significantly reduced relative standard deviations compared to coliform CFU counts in the same...

Short communication: Repeatability of differential goat bulk milk culture and associations with somatic cell count, total bacterial count, and standard plate count.

Science.gov (United States)

Koop, G; Dik, N; Nielen, M; Lipman, L J A

2010-06-01

The aims of this study were to assess how different bacterial groups in bulk milk are related to bulk milk somatic cell count (SCC), bulk milk total bacterial count (TBC), and bulk milk standard plate count (SPC) and to measure the repeatability of bulk milk culturing. On 53 Dutch dairy goat farms, 3 bulk milk samples were collected at intervals of 2 wk. The samples were cultured for SPC, coliform count, and staphylococcal count and for the presence of Staphylococcus aureus. Furthermore, SCC (Fossomatic 5000, Foss, Hillerød, Denmark) and TBC (BactoScan FC 150, Foss) were measured. Staphylococcal count was correlated to SCC (r=0.40), TBC (r=0.51), and SPC (r=0.53). Coliform count was correlated to TBC (r=0.33), but not to any of the other variables. Staphylococcus aureus did not correlate to SCC. The contribution of the staphylococcal count to the SPC was 31%, whereas the coliform count comprised only 1% of the SPC. The agreement of the repeated measurements was low. This study indicates that staphylococci in goat bulk milk are related to SCC and make a significant contribution to SPC. Because of the high variation in bacterial counts, repeated sampling is necessary to draw valid conclusions from bulk milk culturing. 2010 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Evaluation of left ventricular function in patients with atrial fibrillation by ECG gated blood pool scintigraphy. Using frame count normalization method

Energy Technology Data Exchange (ETDEWEB)

Akanabe, Hiroshi; Oshima, Motoo; Sakuma, Sadayuki

1988-07-01

The assumption necessary to perform ECG gated blood pool scintigraphy (EGBPS) are seemingly not valid for patients with atrial fibrillation (af), since they have wide variability in cardiac cycle length. The data were acquired in frame mode within the limits of mean heart rate of fix the first diastolic volume, and were calculated by frame count normalization (FCN) method to correct total counts in each frame. EGBPS were performed twelve patients with af, who were operated against valvular disease. The data acquired within mean heart rate +-10 % in frame mode were divided to 32 frames, and calculated total frame counts. With FCN method total frame counts from at 22nd to 32nd frame were multiplied to be equal to the average of total frame counts. FCN method could correct total frame counts at the latter frames. And there was good correlation between left ventricular ejection fraction calculated from scintigraphy and that from contrast cineangiography. Thus EGBPS with FCN method may be allow estimation of cardiac function even in subjects with af.

Variation in pre-treatment count lead time and its effect on baseline estimates of cage-level sea lice abundance.

Science.gov (United States)

Gautam, R; Boerlage, A S; Vanderstichel, R; Revie, C W; Hammell, K L

2016-11-01

Treatment efficacy studies typically use pre-treatment sea lice abundance as the baseline. However, the pre-treatment counting window often varies from the day of treatment to several days before treatment. We assessed the effect of lead time on baseline estimates, using historical data (2010-14) from a sea lice data management programme (Fish-iTrends). Data were aggregated at the cage level for three life stages: (i) chalimus, (ii) pre-adult and adult male and (iii) adult female. Sea lice counts were log-transformed, and mean counts by lead time relative to treatment day were computed and compared separately for each life stage, using linear mixed models. There were 1,658 observations (treatment events) from 56 sites in 5 Bay Management Areas. Our study showed that lead time had a significant effect on the estimated sea lice abundance, which was moderated by season. During the late summer and autumn periods, counting on the day of treatment gave significantly higher values than other days and would be a more appropriate baseline estimate, while during spring and early summer abundance estimates were comparable among counts within 5 days of treatment. A season-based lead time window may be most appropriate when estimating baseline sea lice levels. © 2016 John Wiley & Sons Ltd.

A manual low background alpha beta counting system

Energy Technology Data Exchange (ETDEWEB)

Levison, S; German, U; Peled, O; Turgeman, S; Vangrovitz, U; Tirosh, D; Piestum, S; Assido, H [Israel Atomic Energy Commission, Beersheba (Israel). Nuclear Research Center-Negev

1996-12-01

An Alpha and Beta counting system consisting of a micro controller-based electronic unit and detectors assembly was developed. The radiation detection unit consists of two proportional detectors (a main detector and a cosmic-ray guard detector) which can be easily disassembled for decontamination or repair. The detectors are mounted in a manual operating sample changer shielded by 5 cm of lead. Simplicity of maintenance and functional operation were taken into consideration in the design. The electronic unit supplies the high voltage and enables the operational functions including controls anti alarms. Calculations of net cpm of Alpha and Beta counting are displayed and can be printed. RS-232 communication option enables connection to a computer and operation of more sophisticated programs for calculations and data storage in the future (authors).

A manual low background alpha beta counting system

International Nuclear Information System (INIS)

Levison, S.; German, U.; Peled, O.; Turgeman, S.; Vangrovitz, U.; Tirosh, D.; Piestum, S.; Assido, H.

1996-01-01

An Alpha and Beta counting system consisting of a micro controller-based electronic unit and detectors assembly was developed. The radiation detection unit consists of two proportional detectors (a main detector and a cosmic-ray guard detector) which can be easily disassembled for decontamination or repair. The detectors are mounted in a manual operating sample changer shielded by 5 cm of lead. Simplicity of maintenance and functional operation were taken into consideration in the design. The electronic unit supplies the high voltage and enables the operational functions including controls anti alarms. Calculations of net cpm of Alpha and Beta counting are displayed and can be printed. RS-232 communication option enables connection to a computer and operation of more sophisticated programs for calculations and data storage in the future (authors)

Biological monitors for low levels of ionising radiation

International Nuclear Information System (INIS)

Mohankumar, M.N.; Jeevanram, R.K.

1995-01-01

The biological effects of high doses of ionising radiation are well understood and the methods of measurement of these doses well established. However the effects due to extremely low doses remain by and large uncertain. This is because of the fact that at such low doses no gross symptoms are seen. In fact, at these levels the occurrence of double strand breaks leading to the formation of chromosomal aberrations like dicentrics is rare and chances of mutation due to base damage are negligible. Hence neither chromosomal aberration studies nor mutational assays are useful for detecting doses of the order of a few milligray. Results of exhaustive work done by various laboratories indicate that below 20 mGy the chromosomal aberration technique based on scoring of dicentrics cannot distinguish between a linear or a threshold model. However indirect methods like unscheduled DNA synthesis (UDS) and sister chromatid exchanges (SCEs) appear to be promising for the detection of radiation exposures due to low levels of radiation. This report reviews the available literature on the biological effects of low levels of ionising radiation and highlights the merits and demerits of the various methods employed in the measurement of UDS and SCE. The phenomenon of radio-adaptive response (RAR) and its relation to DNA repair is also discussed. (author)

Assessment of hemato-biochemical parameters on exposure to low level of deltamethrin in mouse model

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Anita Tewari

2014-03-01

Full Text Available Aim: In this study, sub-acute toxicity of deltamethrin on hematological and biochemical blood parameters of male albino Swiss mice was evaluated. Materials and Methods: Generally, the maximum permissible residue level (MRL of deltamethrin for food products lies between 0.01 to 0.5 mg/kg body weight. So the mice were exposed orally with two doses of pesticide i.e. 0.1 and 0.5 mg/kg body weight. The doses were given on a daily basis for a period of 15 days and 30 days respectively. Ground nut oil was used as control treatment. Samples of blood were collected at the end of the treatment. Hepatotoxicity was evaluated by quantitative analysis of the serum enzymes alanine transaminase (ALT, aspartate transaminase (AST, alkaline phosphatase (ALKP, total bilirubin (TBIL and serum urea. Alterations of hematological parameters were analysed by total leukocyte, differential leukocyte count and hemoglobin levels. Results: Significant increase in the levels of hepatic enzymes (ALT, AST, ALKP were observed for both doses, but no considerable differences were found by histological analysis. The hematological parameters showed significant alterations for 0.5 mg/kg body weight dose which is indicated by leukocytosis, lymphocytosis and neutropenia in long duration study. Conclusions: The results indicated that even very low dose of deltamethrin can promote hematological and hepatic alterations. Thus it is imperative to do further studies on the detrimental effect of the low levels of pyrethroid commonly present in our food, which further necessitate the reduction of maximum permissible levels of residual synthetic pyrethroid levels in foods and feed.

Development of a low-level waste risk methodology

International Nuclear Information System (INIS)

Fisher, J.E.; Falconer, K.L.

1984-01-01

A probabilistic risk assessment method is presented for performance evaluation of low-level waste disposal facilities. The associated program package calculates the risk associated with postulated radionuclide release and transport scenarios. Risk is computed as the mathematical product of two statistical variables: the dose consequence of a given release scenario, and its occurrence probability. A sample risk calculation is included which demonstrates the method. This PRA method will facilitate evaluation of facility performance, including identification of high risk scenarios and their mitigation via optimization of site parameters. The method is intended to be used in facility licensing as a demonstration of compliance with the performance objectives set forth in 10 CFR Part 61, or in corresponding state regulations. The Low-Level Waste Risk Methodology is being developed under sponsorship of the Nuclear Regulatory Commission

Comparison of platelet counts by sysmex XE 2100 and LH-750 with the international flow reference method in thrombocytopenic patients

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Tina Dadu

2013-01-01

Full Text Available Background: There are several methods for counting platelets, of which the international flow reference method (IRM is considered to be the gold standard. We compared the platelet count given by this method to the count given by automated analyzers using other methods, such as optical fluorescence and impedance. Aims: The aim of this study is to compare the platelet counts obtained by Sysmex XE 2100 by Impedance (Sysmex-I, optical florescence (Sysmex-O and reported (Sysmex-R based on the switching algorithm and LH-750 by Impedance (LH-750 with the IRM in thrombocytopenic blood samples. To calculate the sensitivity, specificity, positive predictive value (PPV and negative predictive value (NPV of various technologies at the clinically relevant transfusion thresholds of 10 × 10 9 /l and 20 × 10 9 /l. Materials and Methods: A total of 118 blood samples with platelet count of <50 × 10 9 /l were selected for the study. Platelet counts of all samples were analyzed by all methods using the Sysmex analyzer, LH-750 and IRM in parallel within 6 h of collection. Statistical Analysis Used: Pearson correlation, bland Altman analysis, sensitivity and specificity, PPV and NPV. Results and Conclusions: Sysmex-R had the least Bias and 95% limits of agreement (95%LA range and thus correlated best with IRM values. LH-750 had a higher Bias compared to Sysmex-O and Sysmex-R, but a strikingly similar 95% LA ensures similar results in all three methods. In fact, in the oncology subset, it had the narrowest 95% LA, which made it the best performer in this subgroup. Of the three Sysmex results, Sysmex-I had the highest bias, widest 95% LA and highest potential risk of over transfusion. Hence, Sysmex-R and LH-750 were found to be reliable tools for estimation of platelet count in thrombocytopenic patients.

Impact of advanced and basic carbohydrate counting methods on metabolic control in patients with type 1 diabetes.

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Souto, Débora Lopes; Zajdenverg, Lenita; Rodacki, Melanie; Rosado, Eliane Lopes

2014-03-01

Diets based on carbohydrate counting remain a key strategy for improving glycemic control in patients with type 1 diabetes. However, these diets may promote weight gain because of the flexibility in food choices. The aim of this study was to compare carbohydrate counting methods regarding anthropometric, biochemical, and dietary variables in individuals with type 1 diabetes, as well as to evaluate their knowledge about nutrition. Participants were allocated in basic or advanced groups. After 3 mo of the nutritional counseling, dietary intake, anthropometric variables, lipemia, and glycemic control were compared between groups. A questionnaire regarding carbohydrate counting, sucrose intake, nutritional knowledge, and diabetes and nutrition taboos also was administered. Ten (30%) participants had already used advanced carbohydrate counting before the nutritional counseling and these individuals had a higher body mass index (BMI) (P 1) and waist circumference (WC) (P = 0.01) than others (n = 23; 69.7%). After 3 mo of follow-up, although participants in the advanced group (n = 17; 51.52%) presented higher BMI (P 1) and WC (P = 0.03), those in the basic group (n = 16; 48.48%) showed a higher fat intake (P 1). The majority of participants reported no difficulty in following carbohydrate counting (62.5% and 88% for basic and advanced groups, respectively) and a greater flexibility in terms of food choices (>90% with both methods). Advanced carbohydrate counting did not affect lipemic and glycemic control in individuals with type 1 diabetes, however, it may increase food intake, and consequently the BMI and WC, when compared to basic carbohydrate counting. Furthermore, carbohydrate counting promoted greater food flexibility. Copyright © 2014 Elsevier Inc. All rights reserved.

Low-level radioactive waste management: French and foreign regulations

International Nuclear Information System (INIS)

Coulon, R.

1991-01-01

This paper describes radioactive waste management regulations applied in USA, CANADA, SCANDINAVIA and FRANCE. For low level radioactive wastes, it is necessary to adapt waste management regulations which were firt definite for high level radioactive wastes. So the exemption concept is a simplification method of regulations applied to low radiation sources

A simple method for calibration of Lucas scintillation cell counting system for measurement of 226Ra and 222Rn

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N.K. Sethy

2014-10-01

Full Text Available Known quantity of radium from high grade ore solution was chemically separated and carefully kept inside the cavity of a Lucas Cell (LC. The 222Rn gradually builds up and attain secular equilibrium with its parent 226Ra. This gives a steady count after a suitable buildup period (>25 days. This secondary source was used to calibrate the radon counting system. The method is validated in by comparison with identical measurement with AlphaGuard Aquakit. The radon counting system was used to evaluate dissolved radon in ground water sample by gross alpha counting in LC. Radon counting system measures the collected radon after a delay of >180 min by gross alpha counting. Simultaneous measurement also carried out by AlphaGuard Aquakit in identical condition. AlphaGuard measures dissolved radon from water sample by constant aeration in a closed circuit without giving any delay. Both the methods are matching with a correlation coefficient of >0.9. This validates the calibration of Lucas scintillation cell counting system by designed encapsulated source. This study provides an alternative for calibration in absence of costly Radon source available in the market.

White blood cell counts mediate the effects of physical activity on prostate-specific antigen levels.

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Loprinzi, Paul D; Richart, Sarah M

2014-09-01

The purpose of this study was to examine whether white blood cell (WBC) level mediated the relationship between physical activity and prostate-specific antigen (PSA) levels. Data from the 2003-2006 National Health and Nutrition Examination Survey were used; 1,726 U.S. adult men (aged 40 years or older) provided complete data on the study variables. Participants wore an ActiGraph 7164 accelerometer for a 7-day period to measure their physical activity behavior, and PSA and WBC levels were obtained from a blood sample. After adjustments, results showed that moderate-to-vigorous physical activity (MVPA) was inversely associated with WBC count (b = - .03; 95% CI [ - 0.04, - 0.006; p = .01), and WBC count (b = .10; 95% CI [0.009, 0.18; p = .04) was positively associated with PSA. Both the Sobel (coef. = - .004, SE = .002; z = - 2.0; p = .03) and the Aroian (coef. = - .004, SE = .002; z = - 1.9; p = .03) tests demonstrated that WBC mediated the relationship between physical activity and PSA. Additionally, among 107 participants with prostate cancer, survivors engaging in more MVPA had lower levels of WBC (b = - .04; 95% CI [ - 0.09, - 0.0009; p = .04). Conclusion Physical activity may influence PSA levels through WBC modulation; however, future research is needed to determine the direction of causality. Additionally, prostate cancer survivors engaging in higher levels of MVPA had lower levels of WBC, underscoring the importance of promoting physical activity among prostate cancer survivors.

Study of a photomultiplier for the measurement of low light flows by photon counting

International Nuclear Information System (INIS)

Haye, Kleber

1964-01-01

After a recall of the history of the discovery and use of the photoemission effect, a presentation of the main characteristics of photomultipliers, a discussion of performance and weaknesses of electron multiplier-based cells, this research thesis addresses the study of low light flows. The author tried to determine whether it was possible, at ambient temperature, to reduce the influence of the thermoelectric effect. In order to do so, he made a detailed study of the amplitude spectrum of pulses of photoelectric origin. In order to analyse the influence of temperature of photomultiplier characteristics, he studied, with respect to temperature, the variation of the counting rate corresponding to darkness, the variation of pulse amplitude spectrum, and relative variations of the quantum efficiency for various wavelengths. In parallel with the study by counting, a study has been performed by using the well known mean current measurement [fr

Evaluation of ICT filariasis card test using whole capillary blood: comparison with Knott's concentration and counting chamber methods.

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Njenga, S M; Wamae, C N

2001-10-01

An immunochromatographic card test (ICT) that uses fingerprick whole blood instead of serum for diagnosis of bancroftian filariasis has recently been developed. The card test was validated in the field in Kenya by comparing its sensitivity to the combined sensitivity of Knott's concentration and counting chamber methods. A total of 102 (14.6%) and 117 (16.7%) persons was found to be microfilaremic by Knott's concentration and counting chamber methods, respectively. The geometric mean intensities (GMI) were 74.6 microfilariae (mf)/ml and 256.5 mf/ml by Knott's concentration and counting chamber methods, respectively. All infected individuals detected by both Knott's concentration and counting chamber methods were also antigen positive by the ICT filariasis card test (100% sensitivity). Further, of 97 parasitologically amicrofilaremic persons, 24 (24.7%) were antigen positive by the ICT. The overall prevalence of antigenemia was 37.3%. Of 100 nonendemic area control persons, none was found to be filarial antigen positive (100% specificity). The results show that the new version of the ICT filariasis card test is a simple, sensitive, specific, and rapid test that is convenient in field settings.

Comparison of McMaster and FECPAKG2 methods for counting nematode eggs in the faeces of alpacas.

Science.gov (United States)

Rashid, Mohammed H; Stevenson, Mark A; Waenga, Shea; Mirams, Greg; Campbell, Angus J D; Vaughan, Jane L; Jabbar, Abdul

2018-05-02

This study aimed to compare the FECPAK G2 and the McMaster techniques for counting of gastrointestinal nematode eggs in the faeces of alpacas using two floatation solutions (saturated sodium chloride and sucrose solutions). Faecal eggs counts from both techniques were compared using the Lin's concordance correlation coefficient and Bland and Altman statistics. Results showed moderate to good agreement between the two methods, with better agreement achieved when saturated sugar is used as a floatation fluid, particularly when faecal egg counts are less than 1000 eggs per gram of faeces. To the best of our knowledge this is the first study to assess agreement of measurements between McMaster and FECPAK G2 methods for estimating faecal eggs in South American camelids.

Study on a quantitative evaluation method of equipment maintenance level and plant safety level for giant complex plant system

International Nuclear Information System (INIS)

Aoki, Takayuki

2010-01-01

In this study, a quantitative method on maintenance level which is determined by the two factors, maintenance plan and field work implementation ability by maintenance crew is discussed. And also a quantitative evaluation method on safety level for giant complex plant system is discussed. As a result of consideration, the following results were obtained. (1) It was considered that equipment condition after maintenance work was determined by the two factors, maintenance plan and field work implementation ability possessed by maintenance crew. The equipment condition determined by the two factors was named as 'equipment maintenance level' and its quantitative evaluation method was clarified. (2) It was considered that CDF in a nuclear power plant, evaluated by using a failure rate counting the above maintenance level was quite different from CDF evaluated by using existing failure rates including a safety margin. Then, the former CDF was named as 'plant safety level' of plant system and its quantitative evaluation method was clarified. (3) Enhancing equipment maintenance level means an improvement of maintenance quality. That results in the enhancement of plant safety level. Therefore, plant safety level should be always watched as a plant performance indicator. (author)

Comparison of Drive Counts and Mark-Resight As Methods of Population Size Estimation of Highly Dense Sika Deer (Cervus nippon Populations.

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Kazutaka Takeshita

Full Text Available Assessing temporal changes in abundance indices is an important issue in the management of large herbivore populations. The drive counts method has been frequently used as a deer abundance index in mountainous regions. However, despite an inherent risk for observation errors in drive counts, which increase with deer density, evaluations of the utility of drive counts at a high deer density remain scarce. We compared the drive counts and mark-resight (MR methods in the evaluation of a highly dense sika deer population (MR estimates ranged between 11 and 53 individuals/km2 on Nakanoshima Island, Hokkaido, Japan, between 1999 and 2006. This deer population experienced two large reductions in density; approximately 200 animals in total were taken from the population through a large-scale population removal and a separate winter mass mortality event. Although the drive counts tracked temporal changes in deer abundance on the island, they overestimated the counts for all years in comparison to the MR method. Increased overestimation in drive count estimates after the winter mass mortality event may be due to a double count derived from increased deer movement and recovery of body condition secondary to the mitigation of density-dependent food limitations. Drive counts are unreliable because they are affected by unfavorable factors such as bad weather, and they are cost-prohibitive to repeat, which precludes the calculation of confidence intervals. Therefore, the use of drive counts to infer the deer abundance needs to be reconsidered.

Accuracy of single count methods of WL determination for open-pit uranium mines

International Nuclear Information System (INIS)

Solomon, S.B.; Kennedy, K. N.

1983-01-01

A study of single count methods of WL determination was made using a database respresentative of Australian open pit uranium mine conditions. The aim of the study was to check the existence of the optimum time delay coresponding to the Rolle method, to determine the accuracy of the conversion factor for Australian conditions and to examine any systematic use of data bases of representative radon daughter concentration

Characteristics of Febrile Patients with Normal White Blood Cell Counts and High C-Reactive Protein Levels in an Emergency Department

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Kuan-Ting Liu

2008-05-01

Full Text Available Fever is one of the more common chief complaints of patients who visit emergency departments (ED. Many febrile patients have markedly elevated C-reactive protein (CRP levels and normal white blood cell (WBC counts. Most of these patients have bacterial infection and no previous underlying disease of impaired WBC functioning. We reviewed patients who visited our ED between November 2003 and July 2004. The WBC count and CRP level of patients over 18 years of age who visited the ED because of or with fever were recorded. Patients who had normal WBC count (4,000–10,000/mL and high CRP level (> 100 mg/L were included. The data, including gender, age and length of hospital stay, were reviewed. Underlying diseases, diagnosis of the febrile disease and final condition were recorded according to the chart. Within the study period, 54,078 patients visited our ED. Of 5,628 febrile adults, 214 (3.8% had elevated CRP level and normal WBC count. The major cause of febrility was infection (82.24%. Most of these patients were admitted (92.99%. There were 32 patients with malignant neoplasm, nine with liver cirrhosis, 66 with diabetes mellitus and 11 with uremia. There were no significant differences in age and gender between patients with and those without neoplasm. However, a higher inhospital mortality rate and other causes of febrility were noted in patients with neoplasm. It was not rare in febrile patients who visited the ED to have a high CRP level but normal WBC count. These patients did not necessarily have an underlying malignant neoplasm or hematologic illness. Factors other than malignant neoplasm or hematologic illness may be associated with the WBC response, and CRP may be a better indicator of infection under such conditions.

An improved analytical method for iodine-129 determination in low-level radioactive waste

Energy Technology Data Exchange (ETDEWEB)

Hsieh, Yi-Kong; Wang, TsingHai; Jian, Li-Wei; Chen, Wei-Han; Wang, Chu-Fang [National Tsing Hua Univ., Hsinchu, Taiwan (China). Dept. of Biomedical Engineering and Environmental Sciences; Tsai, Tsuey-Lin [Atomic Energy Council, Taiwan (China). Chemical Analysis Div.

2014-07-01

In this study, an alkaline-digestion pretreatment and a subsequent ICP-MS measurement were conducted for iodine-129 (I-129) determination in low-level radioactive waste. A TMAH + H{sub 2}O{sub 2} + Triton X-100 mixed alkaline digestion was the most effective mixture for I-129 determination. Using this alkaline reagent, a high level of I-129 recovery (101 ± 6%) was achieved for the analysis of the I-129-spiked standard reference materials NIST 2709 and 2711. Importantly, the I-129 concentrations determined for ten real samples provided by the Lan-Yu radioactive waste temporary storage site were found to be below the detection limit (0.011 mg/kg). This value was only approximately 30-70% of the values determined using the I-129/Cs-137 scaling factor. This means that using the I-129/Cs-137 scaling factor severely overestimates the I-129 concentration in these low-level radioactive wastes. We therefore suggest that a detailed re-inspection of the I-129/Cs-137 scaling factor should be performed to appropriately categorize these low-level radioactive wastes.

Role of quenching on alpha/beta separation in liquid scintillation counting for several high capacity cocktails

International Nuclear Information System (INIS)

Pujol, L.; Sanchez-Cabeza, J.-A.

1997-01-01

The optimization of alpha/beta separation in liquid scintillation using pulse shape analysis is convenient for the simultaneous determination of alpha and beta emitters in natural water and other samples. In this work, alpha/beta separation was studied for different scintillant/vial combinations and it was observed that both the optimum pulse shape discrimination level and the total interference value (that is, the summed relative interference between alpha and beta spectra) were dependent on the sample quenching and independent of the scintillant/vial combination. These results provide a simple method for modifying the counting configuration, such as a change in the cocktail, vial or sample characteristics, without the need to perform exhaustive parameter optimizations. Also, it was observed that, for our counting conditions, the combination of Ultima Gold AB scintillation cocktail with Zinsser low diffusion vials presented the lowest total interference, namely 0.94 ± 0.28%, which is insignificant for the counting of environmental samples. (Author)

Validation of analytical methods in GMP: the disposable Fast Read 102® device, an alternative practical approach for cell counting

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Gunetti Monica

2012-05-01

Full Text Available Abstract Background The quality and safety of advanced therapy products must be maintained throughout their production and quality control cycle to ensure their final use in patients. We validated the cell count method according to the International Conference on Harmonization of Technical Requirements for Registration of Pharmaceuticals for Human Use and European Pharmacopoeia, considering the tests’ accuracy, precision, repeatability, linearity and range. Methods As the cell count is a potency test, we checked accuracy, precision, and linearity, according to ICH Q2. Briefly our experimental approach was first to evaluate the accuracy of Fast Read 102® compared to the Bürker chamber. Once the accuracy of the alternative method was demonstrated, we checked the precision and linearity test only using Fast Read 102®. The data were statistically analyzed by average, standard deviation and coefficient of variation percentages inter and intra operator. Results All the tests performed met the established acceptance criteria of a coefficient of variation of less than ten percent. For the cell count, the precision reached by each operator had a coefficient of variation of less than ten percent (total cells and under five percent (viable cells. The best range of dilution, to obtain a slope line value very similar to 1, was between 1:8 and 1:128. Conclusions Our data demonstrated that the Fast Read 102® count method is accurate, precise and ensures the linearity of the results obtained in a range of cell dilution. Under our standard method procedures, this assay may thus be considered a good quality control method for the cell count as a batch release quality control test. Moreover, the Fast Read 102® chamber is a plastic, disposable device that allows a number of samples to be counted in the same chamber. Last but not least, it overcomes the problem of chamber washing after use and so allows a cell count in a clean environment such as that in a

Image quality enhancement in low-light-level ghost imaging using modified compressive sensing method

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Shi, Xiaohui; Huang, Xianwei; Nan, Suqin; Li, Hengxing; Bai, Yanfeng; Fu, Xiquan

2018-04-01

Detector noise has a significantly negative impact on ghost imaging at low light levels, especially for existing recovery algorithm. Based on the characteristics of the additive detector noise, a method named modified compressive sensing ghost imaging is proposed to reduce the background imposed by the randomly distributed detector noise at signal path. Experimental results show that, with an appropriate choice of threshold value, modified compressive sensing ghost imaging algorithm can dramatically enhance the contrast-to-noise ratio of the object reconstruction significantly compared with traditional ghost imaging and compressive sensing ghost imaging methods. The relationship between the contrast-to-noise ratio of the reconstruction image and the intensity ratio (namely, the average signal intensity to average noise intensity ratio) for the three reconstruction algorithms are also discussed. This noise suppression imaging technique will have great applications in remote-sensing and security areas.

Ultra-fast photon counting with a passive quenching silicon photomultiplier in the charge integration regime

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Zhang, Guoqing; Lina, Liu

2018-02-01

An ultra-fast photon counting method is proposed based on the charge integration of output electrical pulses of passive quenching silicon photomultipliers (SiPMs). The results of the numerical analysis with actual parameters of SiPMs show that the maximum photon counting rate of a state-of-art passive quenching SiPM can reach ~THz levels which is much larger than that of the existing photon counting devices. The experimental procedure is proposed based on this method. This photon counting regime of SiPMs is promising in many fields such as large dynamic light power detection.

Hierarchy Low CD4+/CD8+ T-Cell Counts and IFN-γ Responses in HIV-1+ Individuals Correlate with Active TB and/or M.tb Co-Infection.

Science.gov (United States)

Shao, Lingyun; Zhang, Xinyun; Gao, Yan; Xu, Yunya; Zhang, Shu; Yu, Shenglei; Weng, Xinhua; Shen, Hongbo; Chen, Zheng W; Jiang, Weimin; Zhang, Wenhong

2016-01-01

Detailed studies of correlation between HIV-M.tb co-infection and hierarchy declines of CD8+/CD4+ T-cell counts and IFN-γ responses have not been done. We conducted case-control studies to address this issue. 164 HIV-1-infected individuals comprised of HIV-1+ATB, HIV-1+LTB and HIV-1+TB- groups were evaluated. Immune phenotyping and complete blood count (CBC) were employed to measure CD4+ and CD8+ T-cell counts; T.SPOT.TB and intracellular cytokine staining (ICS) were utilized to detect ESAT6, CFP10 or PPD-specific IFN-γ responses. There were significant differences in median CD4+ T-cell counts between HIV-1+ATB (164/μL), HIV-1+LTB (447/μL) and HIV-1+TB- (329/μL) groups. Hierarchy low CD4+ T-cell counts (500/μL) were correlated significantly with active TB but not M.tb co-infection. Interestingly, hierarchy low CD8+ T-cell counts were not only associated significantly with active TB but also with M.tb co-infection (PHierarchy low CD8+ T-cell counts and effector function in HIV-1-infected individuals are correlated with both M.tb co-infection and active TB. Hierarchy low CD4+ T-cell counts and Th1 effector function in HIV-1+ individuals are associated with increased frequencies of active TB, but not M.tb co-infection.

Multiple comparative metagenomics using multiset k-mer counting

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Gaëtan Benoit

2016-11-01

Full Text Available Background Large scale metagenomic projects aim to extract biodiversity knowledge between different environmental conditions. Current methods for comparing microbial communities face important limitations. Those based on taxonomical or functional assignation rely on a small subset of the sequences that can be associated to known organisms. On the other hand, de novo methods, that compare the whole sets of sequences, either do not scale up on ambitious metagenomic projects or do not provide precise and exhaustive results. Methods These limitations motivated the development of a new de novo metagenomic comparative method, called Simka. This method computes a large collection of standard ecological distances by replacing species counts by k-mer counts. Simka scales-up today’s metagenomic projects thanks to a new parallel k-mer counting strategy on multiple datasets. Results Experiments on public Human Microbiome Project datasets demonstrate that Simka captures the essential underlying biological structure. Simka was able to compute in a few hours both qualitative and quantitative ecological distances on hundreds of metagenomic samples (690 samples, 32 billions of reads. We also demonstrate that analyzing metagenomes at the k-mer level is highly correlated with extremely precise de novo comparison techniques which rely on all-versus-all sequences alignment strategy or which are based on taxonomic profiling.

Neutropenia Prediction Based on First-Cycle Blood Counts Using a FOS-3NN Classifier

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Elize A. Shirdel

2011-01-01

Full Text Available Background. Delivery of full doses of adjuvant chemotherapy on schedule is key to optimal breast cancer outcomes. Neutropenia is a serious complication of chemotherapy and a common barrier to this goal, leading to dose reductions or delays in treatment. While past research has observed correlations between complete blood count data and neutropenic events, a reliable method of classifying breast cancer patients into low- and high-risk groups remains elusive. Patients and Methods. Thirty-five patients receiving adjuvant chemotherapy for early-stage breast cancer under the care of a single oncologist are examined in this study. FOS-3NN stratifies patient risk based on complete blood count data after the first cycle of treatment. All classifications are independent of breast cancer subtype and clinical markers, with risk level determined by the kinetics of patient blood count response to the first cycle of treatment. Results. In an independent test set of patients unseen by FOS-3NN, 19 out of 21 patients were correctly classified (Fisher’s exact test probability P<0.00023 [2 tailed], Matthews’ correlation coefficient +0.83. Conclusions. We have developed a model that accurately predicts neutropenic events in a population treated with adjuvant chemotherapy in the first cycle of a 6-cycle treatment.