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High purity germanium (HPGe) detectors are deployed globally for gamma-radiation spectroscopy due to their superior energy resolution. In this work, the essential characteristics of n and p-type HPGe detectors, such as energy resolution, efficiency, minimum detectable activity (MDA), and peak shape were studied for the purpose of characterization and performance optimization. The results are obtained for various source-detector configurations in a wide energy range of 40–1408 keV using gamma sources, such as 109Cd, 57Co, 137Cs, 54Mn, 65Zn, 60Co, and 152Eu. Scanning (distance, lateral, and radial) of the detectors was performed using different gamma sources to understand the orientation of the crystal with its active volume and counting efficiency and to characterize the geometry in detail. The ambient background around the n-type HPGe was reduced using Pb-shielding. As a result, an 85.85% suppression was observed in the mean integral window of 40–2700 keV. The characterization and performance tests of the detectors convincingly suggest that both the detectors can be deployed for environmental radioactivity explorations. [ABSTRACT FROM AUTHOR]

To achieve permanent disposal of radioactive waste drums, the radionuclides analysis process is essential. A variety of waste types are generated through the operation of nuclear facilities, with dry active waste being the most abundant. To perform radionuclides analysis, sample pre-treatment technology is required to transform solid samples into solutions. In this study, we developed a dry ashing-microwave digestion method and secured the reliability of the analysis results through a validity evaluation. Additionally, we conducted a comparative analysis of the radioactivity of 94Nb nuclides with and without the chemical separation process, which reduced the minimum detectable activity level by more than 65-fold for a certain sample. [ABSTRACT FROM AUTHOR]

Copyright of Atomic Energy Science & Technology is the property of Editorial Board of Atomic Energy Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The ISO 11929 standard on characteristic limits in measurements of ionizing radiation extends the concept of the detection limit, originally formalized by Currie, to incorporate the effects of uncertainties in the instrument calibration. The mathematical formulation presented in the standard is known to fail when those uncertainties are too large, however, making it unsuitable for applications where large calibration uncertainties are common. The most recent revision of the standard allows alternative calculation methods to evaluate the detection limit in such circumstances. Results from two such alternative methods are compared here: an approximation combining Gaussian treatment of counting uncertainties with a log-normal representation of the calibration uncertainties, and a numerical evaluation of a statistical modeling approach that accurately represents Poisson counting statistics and accommodates a variety of realistic distributions to describe the calibration uncertainty. Multiple choices of calibration uncertainty distribution for the statistical modeling method are demonstrated and discussed. [ABSTRACT FROM AUTHOR]

Monitoring of tritium concentration in tap water is an essential tool to determine the effective dose received from tap water. Liquid scintillation counting (LSC) is a widely used technique for determining tritium in water. Due to the very low activity of tritium in tap water, its detection requires a high-efficiency LSC with the lowest minimum detectable activity (MDA). Low-level tritium analysis in tap water were performed in two LSC models using conventional distillation techniques. The optimal conditions with the lowest MDAs were applied to determine the tritium concentration in the tap water distributed from two main sources located in the Bangkok metropolitan region: Bang Khen and Maha Sawat water treatment plants (WTPs). Twenty-six tap water samples were collected from petrol stations located around both water treatment plants. The results revealed that the amount of tritium in the tap water around the Bangkhen WTP was between 1.88-2.63 Bq/L with an average of 2.28±0.28 Bq/L, whereas those from the Maha Sawat WTP were between 2.01-2.69 Bq/L with an average of 2.44±0.26 Bq/L, which are far below the World Health Organization's (WHO) guideline limit (10,000 Bq/L) for drinking water. The annual effective dose (AED) for infants, children and adults obtained from tap water samples around the Bangkhen WTP were 0.010, 0.014, and 0.030 µSv/year, respectively, and those from the Maha Sawat WTP were 0.011, 0.015, and 0.032 µSv/year, respectively, which are far below the WHO's guideline limit (100 µSv/year). [ABSTRACT FROM AUTHOR]

The minimum detectable activity (MDA) for gamma spectrometric measurements was studied as a function of filling height for two detectors having different background characteristics and for two sample matrices: a water sample with a low content of natural radionuclides, and zircon sand, with high activities of uranium and thorium. The zircon sand is also a material in which the self-attenuation of low-energy gamma photons will be high. The results show that for the water sample it is always favourable to completely fill the sample container. However, due to the inherent content of naturally occurring radionuclides in the zircon sand the MDA may not necessarily improve with the filling height, since an increased amount of sample will increase the background in the spectrum as well. [ABSTRACT FROM AUTHOR]

A new dipping method was studied for the measurement of radioactive solution using plastic scintillator sheets and pellets (PSs) and a liquid scintillation counter. The method consists of analyzing the PSs dipped into test solution composed of nine compounds with five different radionuclides, and measuring them by using the 'in solution' and 'without solution' method. A qualitative analysis based on the obtained spectra and a quantitative analysis by using the empirical linear relationships between radioactivity and count rate were possible. Minimum detectable activities of this method were calculated and compared with World Health Organization guidelines for drinking water. [ABSTRACT FROM AUTHOR]

We conceptually develop a scintillation-based sensing module for marine gamma-radiation monitoring deployed in an autonomous underwater glider to provide rapid responses to radiological emergencies. First, we replace the forward section of the glider with a robust YAlO3:Ce scintillator, and we analyze several streamlined scintillator configurations with different geometries via simulations of the mechanical and sensing performances. We calculate the minimum thickness required for the scintillator to remain operationally stable in deep ocean water for hemispherical and conical scintillator shapes. Next, we study the advantages and disadvantages of each shape in terms of the drag force and detection efficiency. After the background-radiation estimation of seawater, we calculate the minimum detectable activity (MDA) according to the counting time, which is a key factor in system operation. We find that all configurations can detect 137Cs within 30 min even at distances >600 km from a high-level-nuclear-accident site. Even in relatively minor instances, dozens of hours are sufficient for the optimized sensing module to satisfy a given MDA goal for 137Cs. Our results indicate that radioactivity data can be effectively mapped in 3D by autonomous motion of a monitoring system with the proposed sensing module. [ABSTRACT FROM AUTHOR]

In this contribution, we present and analyze datasnooping in the context of the DIA method. As the DIA method for the detection, identification and adaptation of mismodelling errors is concerned with estimation and testing, it is the combination of both that needs to be considered. This combination is rigorously captured by the DIA estimator. We discuss and analyze the DIA-datasnooping decision probabilities and the construction of the corresponding partitioning of misclosure space. We also investigate the circumstances under which two or more hypotheses are nonseparable in the identification step. By means of a theorem on the equivalence between the nonseparability of hypotheses and the inestimability of parameters, we demonstrate that one can forget about adapting the parameter vector for hypotheses that are nonseparable. However, as this concerns the complete vector and not necessarily functions of it, we also show that parameter functions may exist for which adaptation is still possible. It is shown how this adaptation looks like and how it changes the structure of the DIA estimator. To demonstrate the performance of the various elements of DIA-datasnooping, we apply the theory to some selected examples. We analyze how geometry changes in the measurement setup affect the testing procedure, by studying their partitioning of misclosure space, the decision probabilities and the minimal detectable and identifiable biases. The difference between these two minimal biases is highlighted by showing the difference between their corresponding contributing factors. We also show that if two alternative hypotheses, say Hi and Hj, are nonseparable, the testing procedure may have different levels of sensitivity to Hi-biases compared to the same Hj-biases. [ABSTRACT FROM AUTHOR]

Objective The d2 Test of Attention (D2) is a commonly used measure of selective attention for patients with schizophrenia. However, its test–retest reliability and minimal detectable change (MDC) are unknown in patients with schizophrenia, limiting its utility in both clinical and research settings. The aim of the present study was to examine the test–retest reliability and MDC of the D2 in patients with schizophrenia. Method A rater administered the D2 on 108 patients with schizophrenia twice at a 1-month interval. Test–retest reliability was determined through the calculation of the intra-class correlation coefficient (ICC). We also carried out Bland–Altman analysis, which included a scatter plot of the differences between test and retest against their mean. Systematic biases were evaluated by use of a paired t -test. Results The ICCs for the D2 ranged from 0.78 to 0.94. The MDCs (MDC%) of the seven subscores were 102.3 (29.7), 19.4 (85.0), 7.2 (94.6), 21.0 (69.0), 104.0 (33.1), 105.0 (35.8), and 7.8 (47.8), which represented limited-to-acceptable random measurement error. Trends in the Bland–Altman plots of the omissions (E1), commissions (E2), and errors (E) were noted, presenting that the data had heteroscedasticity. Conclusions According to the results, the D2 had good test–retest reliability, especially in the scores of TN, TN-E, and CP. For the further research, finding a way to improve the administration procedure to reduce random measurement error would be important for the E1, E2, E, and FR subscores. [ABSTRACT FROM AUTHOR]

Objective: Although arthroscopic Bankart repair is widely performed, little is known concerning the healing process of the Bankart lesion. This study aimed to describe the sonographic sequential change of the anteroinferior labrum following arthroscopic Bankart repair, both quantitatively and qualitatively.Materials and Methods: Twenty-five subjects who had undergone arthroscopic Bankart repair were investigated using a sonographic diagnostic device equipped with shear-wave elastographic technology. In addition to measuring the elasticity of the anteroinferior labrum, the B-mode echogram of the anteroinferior labrum was classified into three grades based on the relative echogenicity. Assessment was performed in the affected shoulder 1, 2, 3, 4, 5, 6, and 12 months postoperatively and in the contralateral shoulder 1 month postoperatively for the control.Results: The mean elasticity of the anteroinferior labrum in the affected shoulder 1 and 2 months postoperatively was significantly lower than in the contralateral shoulder (p < 0.001 for both). However, no significant difference was found after 3 months postoperatively. B-mode echograms of the anteroinferior labrum in the contralateral shoulder were classified as grade 0 in all subjects (100%), whereas the percentage of grade 0s in the affected shoulder was 0, 4, 96, and 100% at 1, 2, 3, and 4 months postoperatively.Conclusion: Both quantitative and qualitative assessment of repaired anteroinferior labrum using ultrasound became comparable with the contralateral shoulder 3-4 months postoperatively. Ultrasound is a useful decision-supporting tool to prescribe postoperative rehabilitation protocol following arthroscopic Bankart repair, although functional recovery should also be evaluated on an individual basis. [ABSTRACT FROM AUTHOR]

The international monitoring system (IMS) has been developed to verify compliance with the comprehensive nuclear test-ban treaty (CTBT) and radionuclide monitoring stations are the smoking gun for underground nuclear explosions identification. One of the main objectives of the verification regime is to improve the sensitivity of measurements providing background reduction and, as a result, decrease the minimum detectable activity (MDA) values. At this ENEA laboratory an anticoincidence system has been developed: the system is comprised of a high purity germanium (HPGe) detector surrounded by a low-background shield and two plastic scintillators able to detect coincident cosmic-ray interactions. Tests conducted with the anticoincidence system have shown a reduction of the Compton continuum that contributes to the spectrum background and the measured MDA values, compared to those obtained using the standard system, decreased for all the four radioxenon isotopes. [ABSTRACT FROM AUTHOR]

Purpose. The study aimed to determine the within- and between-session reliabilities as well as the minimal detectable change (MDC) of generally used temporal, kinematic, and kinetic parameters during the sit-to-stand (STS) task in typical children. Methods. The study involved 10 typical children (9.8 ± 1.6 years old). Motion analysis and force plate systems were used to collect markers for 3-dimensional trajectories in space and measure the ground reaction force. The total of 29 reflective markers were placed on each participant's body in accordance with the Helen Hays marker set model by 1 rater on 2 separate days within the span of 1 week. Each subject was asked to perform an STS task 3 times from a height-adjustable chair. Intraclass correlation coefficient (ICC), standard error of measurement (SEM), and MDC for temporal, kinematic, and kinetic parameters were calculated within and between sessions. Results. The results indicated that the temporal parameters achieved excellent (ICC > 0.75), the kinematic parameters presented poor to excellent (0.232 < ICC < 0.997), and the kinetic parameters showed fair to excellent (0.635 < ICC < 0.977) reliabilities in both within- and between-session analyses. The SEM of most kinematic parameters was less than 2° both within and between sessions. In addition, the MDC values for between sessions ranged 1.25-12.64°. Conclusions. The findings support the reliability of using 3-dimensional motion analysis and force plate systems for measuring temporal, kinematic, and kinetic parameters for STS tasks in typical children. [ABSTRACT FROM AUTHOR]

Copyright of Kuwait Journal of Science is the property of Kuwait University, Academic Publication Council and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Plutonium dioxide (PuO2) is used to fabricate a mixed oxide fuel for fast breeder reactors. When a glove box containing PuO2 fails, such as by rupture of a glove or a vinyl bag, airborne contamination of plutonium (Pu) can occur. If a worker inhales PuO2 particles, they will be continually irradiating their lung tissue with alpha particles, and this could cause lung cancer. The nasal smear and nose blow methods are useful for checking workers for PuO2 intake in the field. However, neither method can evaluate the quantitative activity of Pu. No alpha-particle detector that can be used for direct measurements in the nasal cavity has been developed. For direct and quantitative measurement, it is required that a shape of the detector should be a fine bar which inserts itself in the nose to measure the accurate activity of Pu. Therefore, we developed a nasal monitor capable of directly measuring the activity of Pu in the nasal cavity to estimate the internal exposure dose of a worker. Prismatic-shaped 2 × 2 acrylic light guides were used to compose a detector block, and a ZnS(Ag) scintillator was adhered to the surface of these light guides. Silicon photomultiplier (SiPM) arrays with 8 × 8 channels were used as a photodetector. Actual PuO2 particles were measured using the nasal monitor. The nasal monitor could be directly inserted in the nasal cavities, and the activity distribution of Pu was obtained by the nasal monitor. The average efficiencies in 4-pi were 11.4 and 11.6% for the left and right nasal cavities, respectively. The influence of gamma and beta rays from Cesium-137 (137Cs) Strontium-90 (90Sr) on the detection of the alpha particles of Pu was negligible. The difference in the measured Pu activity between the ZnS(Ag) scintillation counter and the nasal monitor was within 4.0%. Therefore, it was considered that the developed nasal monitor could be used in direct Pu determination to estimate the internal exposure dose of workers. [ABSTRACT FROM AUTHOR]

Background: The indication for operative treatment of clavicular fractures with bone shortening over 2 cm is much debated. Correct measurement of clavicular length is essential, and reliable measures of clavicular length are therefore highly requested by clinical decision-makers. The aim of this study was to investigate if three commonly scientifically used measurement methods were interchangeable to each other.Methods: A retrospective study using radiographs collected as part of a previous study on clavicular fractures. Two independent raters measured clavicle shortening on 60 patients using conventional radiographs on two separate sessions. The two measurement methods described by Hill et al. and Silva et al. were used on unilateral pictures. Side difference measurements according to Lazarides et al. were made on panoramic radiographs. The measurements were analyzed using intraclass correlation, Weir's protocol for Standard error of measurement (SEM) and minimal detectable change (MDC), and Bland-Altman plots.Results: None of the methods were directly interchangeable. The side difference method by Lazarides et al. was the most reliable of the three methods, but had a high proportion of post-fracture bone lengthening that indicated methodological problems. The Hill et al. and Silva et al. methods had high minimal detectable change, making their use unreliable.Conclusion: As all three measurement methods had either reliability or methodological issues, we found it likely that differences in measurement methods have caused the differences in clavicular length observed in scientific studies. [ABSTRACT FROM AUTHOR]

Introduction:Several researchers have demonstrated the positive benefits of auditory and visual cueing in the gait improvements among individuals with Parkinson’s disease (PD). However, few studies have evaluated the role of vibrotactile cueing when compared to auditory and visual cueing. This paper compares how these stimuli affect the risk of falling while walking on six types of soil (concrete, sand, parquet, broken stone, two types of carpet). Methods:An instrumented Timed Up and Go (iTUG) test served to evaluate how audio, visual and vibrotactile cueing can affect the risk of falling of elderly. This pilot study proposes 12 participants with PD (67.7 ± 10.07 years) and nine age-matched controls (66.8 ± 8.0 years). Both groups performed the iTUG test with and without cueing. The cueing frequency was set at 10% above the cadence computed at the lower risk level of falling (walking over the concrete). A computed risk of falling (ROFA) index has been compared to the TUG time (total TUG duration). Results:The index for evaluating the risk of falling appears to have a good reliability (ICC > 0.88) in this pilot study. In addition, the minimal detectable change (MDC) suggests that the proposed index could be more sensitive to the risk of falling variation compared to the TUG time. Moreover, while using the cueing, observed results suggest a significant decrease in the computed risk of falling compared to ‘without cueing’ for most of types of soil, especially for deformable soils, which can lead to falls. Conclusion:When compared to other cueing, it seems that audio could be a better neurofeedback for reducing the risk of falling over different walking surfaces, which represent important risk factors for persons with gait disorder or lost functional autonomy. [ABSTRACT FROM AUTHOR]

We prove that, under some conditions, a linear nonautonomous difference system is Bylov's almost reducible to a diagonal one whose terms are contained in the Sacker and Sell spectrum of the original system. In the above context, we provide an example of the concept of diagonally significant system, recently introduced by Pötzsche. This example plays an essential role in the demonstration of our results. [ABSTRACT FROM AUTHOR]

In this paper we investigate the spectral expansion for the one-dimensional Schrodinger operator with a periodic complex-valued potential. For this we consider in detail the spectral singularities and introduce new concepts as essential spectral singularities and singular quasimomenta. [ABSTRACT FROM AUTHOR]

Our goal was to develop a mobile tritium monitor for continuous inflow system for water sample. The system is based on electrolysis and a plastic scintillator detection system. The minimum detectable activity (MDA) of the prototype system is 431 kBq L, while the MDA of a commercially available product is 740 kBq L. We expected to achieve a 5.73-times lower MDA by optimizing detection geometry using a multi-hydrogen-gas-channel. The system can be applied either as a mobile leakage surveying method or as a fixed-type monitor for detecting tritium in drinking water by adapting conventional background reduction technologies. [ABSTRACT FROM AUTHOR]

Developments in radioxenon monitoring since the implementation of the International Monitoring System are reviewed with emphasis on the most current technologies to improve detector sensitivity and resolution. The nuclear detectors reviewed include combinations of plastic and NaI(Tl) detectors, high purity germanium detectors, silicon detectors, and phoswich detectors. The minimum detectable activity and calibration methods for the various detectors are also discussed. [ABSTRACT FROM AUTHOR]

Before integration aboard European Space Agency BepiColombo mission to Mercury, the visible and near infrared hyperspectral imager underwent an intensive calibration campaign. We report in Paper I about the radiometric and linearity responses of the instrument including the optical setups used to perform them. Paper II [F. Altieri et al., Rev. Sci. Instrum. 88, 094503 (2017)] will describe complementary spectral response calibration. The responsivity is used to calculate the expected instrumental signal-to-noise ratio for typical observation scenarios of the BepiColombo mission around Mercury. A description is provided of the internal calibration unit that will be used to verify the relative response during the instrument’s lifetime. The instrumental spatial response functions as measured along and across the spectrometer’s slit direction were determined by means of spatial scans performed with illuminated test slits placed at the focus of a collimator. The dedicated optical setup used for these measurements is described together with the methods used to derive the instrumental spatial responses at different positions within the 3.5° field of view and at different wavelengths in the 0.4–2.0 μm spectral range. Finally, instrument imaging capabilities and Modulated Transfer Function are tested by using a standard mask as a target. [ABSTRACT FROM AUTHOR]

Recalculation of spectral sensitivity of photodetector arrays with a relatively low signal-to-noise ratio necessitates the analysis of noise filtering with maintaining of the positions of boundaries and maximum sensitivity. Methods for filtering of spectral characteristics of sensitivity (moving average method and its modifications, spline interpolation, calculations using the Bezier curves, and Savitzky-Golay procedure) are compared. Criteria for selection of nondestructive calculation procedure that does not introduce errors in the boundaries of the range and maximum sensitivity of photodetector arrays are determined. An optimal method for recalculation of spectral sensitivities of photodetector arrays is chosen and substantiated. [ABSTRACT FROM AUTHOR]

Gamma spectrometry for environmental samples of low specific activities demands low minimum detection levels of measurement. An attempt has been made to lower the gamma detection level of measurement by optimizing the sample geometry, without compromising on the sample size. Gamma energy of 50-200 keV range was chosen for the study, since low energy gamma photons suffer the most self-attenuation within matrix. The simulation study was carried out using MCNP based software "EffCalcMC" for silica matrix and cylindrical geometries. A volume of 250 ml sample geometry of 9 cm diameter is optimized as the best suitable geometry for use, against the in-practice 7 cm diameter geometry of same volume. An increase in efficiency of 10%-23% was observed for the 50-200 keV gamma energy range and a corresponding lower minimum detectable activity of 9%-20% could be achieved for the same. [ABSTRACT FROM AUTHOR]

The content of carbon and nitrogen is the important index for quality monitoring in groundwater. For measuring the concentration of carbon and nitrogen simultaneously in aqueous solution, a PGNAA setup with a D-T neutron generator and a 4 × 4 inch BGO detector has been designed with Monte Carlo simulations. The size of setup, after optimization by using MCNP, was set as 60 cm × 60 cm (diameter × height). Moreover, the measurement has been achieved, and the results showed that the carbon and nitrogen had a good linearity between their own concentration and characteristic peak, with the correlation coefficient reaching almost at 1. Also the results were well matched with the results of MCNP simulation. Finally the minimum detectable concentrations (MDC) of carbon and nitrogen have been discussed, respectively. [ABSTRACT FROM AUTHOR]

Purpose For CT dose optimization, one needs to address two important questions. The first is how various lesion-specific detection tasks demand different patient doses for the same patient. The second is how the variation of the patient size requires different patient doses for the same lesion detection task. In this study, we attempted to find quantitative solutions to these questions by utilizing a wide range of abdomen phantoms. Methods A simplified model with a monochromatic fan beam passing through a bowtie-filter and an elliptical object was proposed. The model relates the minimum detectable contrast (MDC) to the size-specific dose by power index of −1/2 and to the lesion size by power index of −1 with a patient size dependence function (PSDF) as the proportionality factor. The experimental validation was performed using seven abdomen phantoms (lateral ranges: 10 cm-39 cm) scanned with helical modes at various dose levels on two 64-slice scanners (Siemens mCT and GE HD 750). Noise images were obtained using subtractions among adjacent slices in the images reconstructed with filtered backprojection. It was verified that the mean pixel value distributions from various small regions (1.8 mm-10 mm) are Gaussian, thus the concept of the statistically defined minimum detectable contrast (SD-MDC), defined as distribution's standard deviation multiplied by 3.29, can be applied. The impact of the helical pitch and the high-definition (HD) acquisition was also studied. Results The experimental data from all phantoms were found to fit the power law well (R2 ≥ 0.983). The PSDF was found to be scanner dependent - modeled with a Gaussian amplifier (R2 = 0.983) for one manufacturer and with an exponential function for the other (R2 = 0.990). The MDC relationship was not found to be impacted by different pitches or by HD acquisition. The results were used to find the size-specific doses and corresponding acquisition techniques required by consistent low-contrast detectability for variable patient sizes. Visual comparisons on the low-contrast insert images demonstrated that the derived techniques delivered consistent low-contrast detectability. Conclusions We have modeled and verified the relationship of the minimum detectable contrast to the patient size, the patient dose, and the lesion size from the images reconstructed with filtered backprojection. The findings can be useful for task-specific dose modulation on abdomen CT studies. [ABSTRACT FROM AUTHOR]

The aim of this paper is to compare radioxenon beta-gamma analysis algorithms using simulated spectra with experimentally measured background, where the ground truth of the signal is known. We believe that this is among the largest efforts to date in terms of the number of synthetic spectra generated and number of algorithms compared using identical spectra. We generate an estimate for the minimum detectable counts for each isotope using each algorithm. The paper also points out a conceptual model to put the various algorithms into a continuum. Our results show that existing algorithms can be improved and some newer algorithms can be better than the ones currently used. [ABSTRACT FROM AUTHOR]

The distinct behaviours of animals and the varied habitats in which animals live place different requirements on their visual systems. A trade-off exists between resolution and sensitivity, with these properties varying across the retina. Spectral sensitivity, which affects both achromatic and chromatic (colour) vision, also varies across the retina, though the function of this inhomogeneity is less clear. We previously demonstrated spatially varying spectral sensitivity of double cones in the cichlid fish Metriaclima zebra owing to coexpression of different opsins. Here, we map the distributions of ganglion cells and cone cells and quantify opsin coexpression in single cones to show these also vary across the retina. We identify an area centralis with peak acuity and infrequent coexpression, which may be suited for tasks such as foraging and detecting male signals. The peripheral retina has reduced ganglion cell densities and increased opsin coexpression. Modeling of cichlid visual tasks indicates that coexpression might hinder colour discrimination of foraging targets and some fish colours. But, coexpression might improve contrast detection of dark objects against bright backgrounds, which might be useful for detecting predators or zooplankton. This suggests a trade-off between acuity and colour discrimination in the central retina versus lower resolution but more sensitive contrast detection in the peripheral retina. Significant variation in the pattern of coexpression among individuals, however, raises interesting questions about the selective forces at work. [ABSTRACT FROM AUTHOR]

Minimal Detectable Biases (MDBs) or Minimal Detectable Outliers for the Expectation Maximization (EM) algorithm based on the variance-inflation and the mean-shift model are determined for an example. A Monte Carlo method is applied with no outlier and with one, two and three randomly chosen outliers. The outliers introduced are recovered and the corresponding MDBs are almost independent from the number of outliers. The results are compared to the MDB derived earlier by the author. This MDB approximately agrees with the MDB for one outlier of the EM algorithm. The MDBs for two and three outliers are considerably larger than MDBs of the EM algorithm. [ABSTRACT FROM AUTHOR]

This paper presents the statistical concepts used in power calculations for experimental design. It provides detailed definitions of parameters used to perform power calculations, useful rules of thumb and different approaches that can be used when performing power calculations. The authors draw from real-world examples to calculate statistical power for individual and cluster randomised controlled trials. This paper provides formulae for sample size determination and minimum detectable effect (MDE) associated with a given statistical power. The paper is accompanied by the sample size and MDE calculator©, a free online tool that allows users to work with the formulae presented in Section 4. [ABSTRACT FROM PUBLISHER]

In this work, a prototype radioxenon detection system was designed, developed and tested at Oregon State University to study the response of CdZnTe (CZT) detectors to xenon radioisotopes for monitoring nuclear explosions. The detector utilizes two coplanar CZT detectors and measures xenon radioisotopes through beta-gamma coincidence detection between the two detection elements. The CZT-based detection system offers excellent energy resolution and background count rate compared with scintillator-based beta-gamma coincidence detectors currently in operation at the IMS stations. In this paper, we briefly discuss the detector design and report our recent measurement results with Xe, Xe, and Xe produced in the TRIGA reactor at OSU. [ABSTRACT FROM AUTHOR]

Objective: The Conners' Continuous Performance Test II (CCPT-II) is one of the most commonly used tests of sustained attention in schizophrenia. To manage and monitor sustained attention deficits in schizophrenia, clinicians have to reliably assess the degree of attention impairment. The purpose of our study was to determine the relative and absolute reliability of the CCPT-II in schizophrenia. Method: The final sample was a total of 108 patients with schizophrenia. The primary measures in this study were the CCPT-II and the Clinical Global Impression-Severity (CGI-S). The CCPT-II was administered twice, 1 month apart, by a specially trained occupational therapist. We assessed two types of reliability: relative and absolute reliability. Relative reliability was determined with the intra-class correlation coefficient (ICC). Absolute reliability was quantified with standard error of measurement (SEM), minimal detectable change (MDC), and Bland-Altman's 95% limits of agreement (LOA). Results: The ICCs for the five CCPT-II indexes (Omissions, Commissions, Hit RT, Hit RT Std Error, and Variability) ranged from 0.66 to 0.79. The MDCs (MDC%) of the five indices were 13.53 (156.78), 10.67 (47.85), 122.10 (34.16), 8.15 (106.82), and 25.81 (162.63), respectively. Conclusions: According to the results, the CCPT-II has limited reliability in monitoring the sustained attention function of patients with schizophrenia. Our results can be used as a reference for the measurement error of CCPT-II to help clinicians and researchers determine the true change between successive assessments of patients with schizophrenia. [ABSTRACT FROM AUTHOR]

Background: Pressure pain thresholds (PPT) are commonly used to quantify mechanical pain sensitivity of deep structures. Excellent PPT reliability has been previously reported among the low back of healthy subjects. However, there is a lack of studies assessing PPT over the low back of workers exposed to biomechanical risk factors of low back pain. Thus, the purpose of this study was threefold: (1) to evaluate the intra-session absolute and relative reliability as well as minimal detectable change (MDC) values of PPT within 14 locations covering the low back region of vine-workers and (2) to determine the number of trial required to ensure reliable PPT assessments and (3) to assess the effect of modifier factors such as gender, age, body mass index (BMI) and pain intensity on PPT reliability.Methods: Twenty-nine vine-workers voluntarily participated in this study. Twenty-two reported low intensity of low-back pain while seven were pain-free. PPTs were assessed among 14 anatomical locations in the lower back region. Three trials were performed on each location with an interval time of at least one minute. Reliability was assessed computing intraclass correlation coefficients (ICC), standard error of measurement (SEM) for all possible combinations between trials. Bland-Altman plots were also generated to assess potential bias in the dataset. Finally, a repeated measure analysis of variance (RM-ANOVA) with the number of trials used as within subject factor was performed on (1) PPT, (2) ICC and (3) SEM values.Results: ICC ranged from 0.86 to 0.99 for all anatomical locations and for all possible combinations between trials. SEM for comparison between trial 1-2, 2-3, 1-3 and, 1-2-3 ranged from respectively, 36.7-77.5, 27.8-77.7, 50-95.2 and, 39.3-80.8 kPa. ICC and SEM remained similar to the ones obtained for the entire population when taking modifier factors in consideration. The visual analysis of Bland-Altman plots suggested small measurement errors for all anatomical locations and for all possible combinations between trials.Conclusions: The assessment of PPTs of the lower back among vine-workers was found to have excellent relative and absolute reliability. Moreover, reliable measurements can be equally achieved when using the mean of three PPT measurement or with the first one. [ABSTRACT FROM AUTHOR]

A comprehensive description of the spectral characteristics of retinal photoreceptors in palaeognaths is lacking. Moreover, controversy exists with respect to the spectral sensitivity of the short-wavelength-sensitive-1 (SWS1) opsin-based visual pigment expressed in one type of single cone: previous microspectrophotometric (MSP) measurements in the ostrich (Struthio camelus) suggested a violet-sensitive (VS) SWS1 pigment, but all palaeognath SWS1 opsin sequences obtained to date (including the ostrich) imply that the visual pigment is ultraviolet-sensitive (UVS). In this study, MSP was used to measure the spectral properties of visual pigments and oil droplets in the retinal photoreceptors of the emu (Dromaius novaehollandiae). Results show that the emu resembles most other bird species in possessing four spectrally distinct single cones, as well as double cones and rods. Four cone and a single rod opsin are expressed, each an orthologue of a previously identified pigment. The SWS1 pigment is clearly UVS (wavelength of maximum absorbance [λmax] = 376 nm), with key tuning sites (Phe86 and Cys90) consistent with other vertebrate UVS SWS1 pigments. Palaeognathswould appear, therefore, to have UVS SWS1 pigments. As they are considered to be basal in avian evolution, this suggests that UVS is the most likely ancestral state for birds. The functional significance of a dedicated UVS cone type in the emu is discussed. [ABSTRACT FROM AUTHOR]

Purpose: The aim of the study was to develop a Dutch language version of the Foot and Ankle Ability Measure (FAAM) and evaluate its measurement properties according to the consensus-based standards for the selection of health measurement instruments (COSMIN) definitions.Methods: A forward-backward translation procedure was performed and subsequently the Dutch version of the FAAM was evaluated for its reliability and validity in 369 patients with a variety of foot and ankle complaints. The reliability was assessed by calculating the intraclass correlation coefficients (ICC, test-retest reliability), Cronbach's alpha (internal consistency), the standard error of measurement and the minimal detectable change (MDC). Additionally, this was done for athletes. The construct validity was assessed by the use of Spearman's correlation coefficient between FAAM domains and similar and contradictory domains of the Foot and Ankle Outcome Score, Short Form 36 and the Numeric Rating Scale for pain.Results: The ICC of the subscales ranged from 0.62 to 0.86. Cronbach's alpha's minimum was 0.97. At individual level, the MDC ranged from 23.9 to 44.7 and at group level from 2.77 to 4.32. In the subgroup of athletes, the reliability was higher. The hypothesized correlations of the construct validity were supported by an 80% confirmation rate.Conclusion: The Dutch version of the FAAM met adequate measurement properties, although the reliability is not optimal. The FAAM-Sport subscale is more useful in athletes and the FAAM-Sport % seems not to contribute. In athletes with various foot and ankle symptoms, the FAAM can be used for functional assessment and follow-up at group level. For the general population, the FAAM is less appropriate.Level Of Evidence: Diagnostic study, Level I. [ABSTRACT FROM AUTHOR]

The use of the normalized differential spectral attenuation (NDSA) approach in the microwaves and (later) in the millimeter waves has been recently introduced to retrieve information about integrated water vapor (IWV) content from attenuation measurements along microwave links between two low Earth orbit (LEO) satellites. NDSA was originally proposed for a configuration of two counter-rotating satellites, to achieve vertical profiles of water vapor (WV) from IWV measurements. In this paper, we analyze the exploitability of the NDSA approach in the case of a constellation of corotating LEO satellites in order to estimate the WV content in a 2-D field lying in the orbital plane of the satellites. The WV retrieval is formalized as the solution of an inverse problem. Simulation results are presented in order to demonstrate the feasibility of the proposed approach: a complete acquisition system composed of transmitting and receiving LEO satellites, including tropospheric scintillation effects, has been modeled, and the reconstruction of 2-D maps of the atmospheric WV from multiple IWV measurements is shown. [ABSTRACT FROM AUTHOR]

The optimal measurement counting time for gamma-ray spectrometry analysis using HPGe detectors was determined in our laboratory by studying the correlation between the minimum detectable activity and the measurement counting time. For a system using a HPGe P-type (80 %) detector, the optimal measurement counting time was determined to be 15 h for energy lines higher than 100 keV and 20 h for energy lines lower than 100 keV. For a system using a HPGe N-type (60 %) detector, the optimal counting time was determined to be 15 h. It was found that knowing the optimal measurement counting times is practical when determining detection limits for long-lived radionuclides, such as to satisfy laboratory accreditation technical requirements relevant for ISO 17025:2005. [ABSTRACT FROM AUTHOR]

The concept of minimal detectable bias (MDB) as initiated by Baarda (Publ Geod New Ser 2(5), ) and later developed by Wang and Chen (Acta Geodaet et Cartograph Sin Engl Edn 42-51, ), Schaffrin (J Eng Surv 123:126-137, ), Teunissen (IEEE Aerosp Electron Syst Mag 5(7):35-41, , J Geod 72:236-244 , Testing theory: an introduction. Delft University Press, Delft, ) and others, refers to the issue of outlier detectability. A supplementation of the concept is proposed for the case of correlated observations contaminated with a single gross error. The supplementation consists mainly of an outlier identifiability index assigned to each individual observation in a network and a mis-identifiability index being the maximum probability of identifying a wrong observation. To those indices there can also be added the MDB multiplying factor to increase the identifiability index to a satisfactory level. As auxiliary measures there are indices of partial identifiability concerning pairs of observations. The indices were derived assuming the generalized outlier identification procedure as in Knight et al. (J Geod. doi:, ), which with one outlier case being assumed is similar to Baarda's w-test (Baarda in Publ Geod New Ser 2(5), ). The following two options of identifiability indices and partial identifiability indices are distinguished: I. the indices related to identification of a contaminated observation within a set of observations suspected of containing a gross error (identifiability), II. the indices related to identification of a contaminated observation within a whole set of observations (pseudo-identifiability). To characterize the proposed approach in the context of the existing solutions of similar topic being the separability testing, the properties of both types of identifiability indices are discussed with reference to the concept of Minimal Separable Bias (Wang and Knight in J Glob Position Syst 11(1):46-57, ) and a general approach in Yang et al. (J Geod 87(6):591-604, ). Numerical examples are provided to verify the proposed approach. [ABSTRACT FROM AUTHOR]

Background: The Patient-rated Wrist Evaluation (PRWE) is a commonly used instrument in upper extremity surgery and in research. However, to recognize a treatment effect expressed as a change in PRWE, it is important to be aware of the minimum clinically important difference (MCID) and the minimum detectable change (MDC). The MCID of an outcome tool like the PRWE is defined as the smallest change in a score that is likely to be appreciated by a patient as an important change, while the MDC is defined as the smallest amount of change that can be detected by an outcome measure. A numerical change in score that is less than the MCID, even when statistically significant, does not represent a true clinically relevant change. To our knowledge, the MCID and MDC of the PRWE have not been determined in patients with distal radius fractures. Questions/Purposes: We asked: (1) What is the MCID of the PRWE score for patients with distal radius fractures? (2) What is the MDC of the PRWE? Methods: Our prospective cohort study included 102 patients with a distal radius fracture and a median age of 59 years (interquartile range [IQR], 48-66 years). All patients completed the PRWE questionnaire during each of two separate visits. At the second visit, patients were asked to indicate the degree of clinical change they appreciated since the previous visit. Accordingly, patients were categorized in two groups: (1) minimally improved or (2) no change. The groups were used to anchor the changes observed in the PRWE score to patients' perspectives of what was clinically important. We determined the MCID using an anchor-based receiver operator characteristic method. In this context, the change in the PRWE score was considered a diagnostic test, and the anchor (minimally improved or no change as noted by the patients from visit to visit) was the gold standard. The optimal receiver operator characteristic cutoff point calculated with the Youden index reflected the value of the MCID. Results: In our study, the MCID of the PRWE was 11.5 points. The area under the curve was 0.54 (95% CI, 0.37-0.70) for the pain subscale and 0.71 (95% CI, 0.57−0.85) for the function subscale. We determined the MDC to be 11.0 points. Conclusions: We determined the MCID of the PRWE score for patients with distal radius fractures using the anchor-based approach and verified that the MDC of the PRWE was sufficiently small to detect our MCID. Clinical Relevance: We recommend using an improvement on the PRWE of more than 11.5 points as the smallest clinically relevant difference when evaluating the effects of treatments and when performing sample-size calculations on studies of distal radius fractures. [ABSTRACT FROM AUTHOR]

This study is aimed at the determination of the measurement properties of the shoulder function B-B Score measured with a smartphone. This score measures the symmetry between sides of a power-related metric for two selected movements, with 100% representing perfect symmetry. Twenty healthy participants, 20 patients with rotator cuff conditions, 23 with fractures, 22 with capsulitis, and 23 with shoulder instabilities were measured twice across a six-month interval using the B-B Score and shoulder function questionnaires. The discriminative power, responsiveness, diagnostic power, concurrent validity, minimal detectable change (MDC), minimal clinically important improvement (MCII), and patient acceptable symptom state (PASS) were evaluated. Significant differences with the control group and significant baseline-six-month differences were found for the rotator cuff condition, fracture, and capsulitis patient groups. The B-B Score was responsive and demonstrated excellent diagnostic power, except for shoulder instability. The correlations with clinical scores were generally moderate to high, but lower for instability. The MDC was 18.1%, the MCII was 25.2%, and the PASS was 77.6. No floor effect was observed. The B-B Score demonstrated excellent measurement properties in populations with rotator cuff conditions, proximal humerus fractures, and capsulitis, and can thus be used as a routine test to evaluate those patients. [ABSTRACT FROM AUTHOR]

A new method of directly measuring 222Rn progeny in a worker′s lung using a lung counting system is introduced. To determine the efficiency of the lung counting system, a torso phantom manufactured by the China Institute for Radiation Protection was used, where activated carbon that had been loaded in a radon chamber with a defined quantity of radon represented the lungs, which were usually made of urethane foam. The minimum detectable activity (MDA) of 214Bi, one of the 222Rn progenies, was estimated to be 7.3 Bq for a measurement time of 4000 s. Based on the time 222Rn progenies stay in the lung, it may be concluded that the lung counting system described can be well used for directly measuring the activity of 214Bi in the lung short time after a worker inhaled 222Rn at his/her workplace. [ABSTRACT FROM AUTHOR]

In the European registration procedure for pesticides, microcosm and mesocosm studies are the highest aquatic experimental tier to assess their environmental effects. Evaluations of microcosm/mesocosm studies rely heavily on no observed effect concentrations (NOECs) calculated for different population-level endpoints. Ideally, a power analysis should be reported for the concentration-response relationships underlying these NOECs, as well as for measurement endpoints for which significant effects cannot be demonstrated. An indication of this statistical power can be provided a posteriori by calculated minimum detectable differences (MDDs). The MDD defines the difference between the means of a treatment and the control that must exist to detect a statistically significant effect. The aim of this paper is to expand on the Aquatic Guidance Document recently published by the European Food Safety Authority (EFSA) and to propose a procedure to report and evaluate NOECs and related MDDs in a harmonised way. In addition, decision schemes are provided on how MDDs can be used to assess the reliability of microcosm/mesocosm studies and for the derivation of effect classes used to derive regulatory acceptable concentrations. Furthermore, examples are presented to show how MDDs can be reduced by optimising experimental design and sampling techniques. [ABSTRACT FROM AUTHOR]

The determination of the effective minimum detectable activity (MDA) of radionuclides by a detection system plays an important role in environmental radiation monitoring. In this study, the responses of an NaI(Tl) airborne γ ray spectrometry (AGRS) system to different radionuclides (Cs and I) were investigated using the Monte Carlo technique. The MDA values were determined under different conditions according to the counting spectra obtained from the Monte Carlo simulation. The equivalent mass thickness method was applied to the Monte Carlo modeling for monitoring ground radiation to reduce statistical uncertainty. The secondary source method was used to monitor both air and ground radiation. A quadratic relationship was found between the MDA and activity concentration. An exponential relationship was found between the MDA and altitude. The MDA of a specific radionuclide from external detectors was found to be superior to that obtained from internal detectors under the same conditions. The MDA values in an NaI(Tl) AGRS system under different conditions can be estimated based on the results of this study. [ABSTRACT FROM AUTHOR]

Background The Child Health Questionnaire (CHQ) is a widely used instrument for measuring health-related quality of life covering both the physical and psychosocial domain. This study examined the responsiveness of the Dutch CHQ 50-item Parent Form ( PF50) in a sample of adolescents with chronic non-specific pain and/or fatigue. Method Five different methods were used to calculate the responsiveness for the physical ( PhS) and psychosocial ( PsS) subscale of the CHQ-50: standardized response mean ( SRM), pooled effect sizes ( ESs), standard error of measurement of agreement ( SEMagreement), minimal detectable change ( MDC) and the area under the receiver operating characteristics ( ROC) curve. For data analysis, the population was divided into two groups based on the parent's global perceived effect of treatment: a changed group (A) and an unchanged group (B). Results The responsiveness analyses were performed including 92 adolescents (88.0% girls; mean age 16.4 years). The SRMs are 2.89 and 1.01 for the PhS and PsS, respectively. Large ESs are found for group A ( PhS = 3.30; PsS = 1.16). The method used for calculating SEMagreement results in a score of PhS = 18.92 and PsS = 11.39. The MDCs of PhS and PsS are 52.45 and 31.57, respectively. The area under the ROC curve ( AUC) for PhS = 0.79 and for PsS = 0.64, and the corresponding optimal cut-off points are 21.1 and 7.0. Conclusion Using the methods SRM, ES and AUC, the responsiveness of the CHQ- PF50 in adolescents with non-specific chronic pain or fatigue treated in a rehabilitation clinic is adequate for the physical scale and moderate for the psychosocial scale. [ABSTRACT FROM AUTHOR]

The analysis of 226Ra, 232Th and 40K radionuclides has been carried out in geothermal water and residue samples collected from six wells of geothermal power plant and disposal site, using gamma-spectrometry system equipped with a high-purity germanium detector. The activity concentrations of nine geothermal water samples were found to be lower than minimum detectable activity (MDA) values. The activity concentration of the residue samples ranged from 40±4 to 2694±85 Bq kg−1 for 226Ra, 33±4 to 2388±85 Bq kg−1 for 232Th, and MDA value to 967±30 Bq kg−1 for 40K. In the study, some radiological indexes were examined and found to be higher than the reference values for majority of the residue samples. The annual effective doses arising from some residue samples were calculated to be higher than the permitted dose rate for the public, i.e. 1 mSv y−1. [ABSTRACT FROM PUBLISHER]

The influence of electron-phonon interaction on the shape of the optically stimulated luminescence decay curve of AlO:C has been studied using thermally assisted optically stimulated luminescence (TA-OSL). The minimum detectable dose (MDD) of a phosphor depends on the standard deviation of the background signal which affects the signal-to-noise ratio. The standard deviation of the background signal reduces at lower stimulation light intensity while the readout time increases. Further, measurement at higher temperature enhances the OSL signal with faster decay due to the temperature dependence of photo-ionization cross-section. To achieve the same decay constant and more signal, the temperature of measurement was raised. As a result of lowering the stimulation in-tensity at higher temperature (85°C) the overall MDD of α-AlO:C was found to improve by 1.8 times. For extension of dose linearity in higher range, deeper traps were studied by simultaneous application of CW-OSL and thermal stimulation up to 400°C, using a linear heating rate of 4K/s. By using this method, two well defined peaks at 121°C and 232°C were observed. These TA-OSL peaks have been correlated with two deeper defects which can be thermally bleached at 650°C and 900°C respectively. These deeper defects are stable up to 500°C, so they can store absorbed dose information even if the sample is inadvertently exposed to light or heat. The dose vs. TA-OSL response from deep traps of α-AlO:C was found to be linear up to 10 kGy, thus extending its application for high dose dosimetry. [ABSTRACT FROM AUTHOR]

Purpose: In this work, the authors aim for the estimation of the effect of 176Lu intrinsic radioactivity on the performance of a dual head PET system dedicated to small animal imaging. Methods: A prototype camera has been used as a reference system in order to validate two GATE simulation models, which were used for the investigation. The first model includes the 176Lu intrinsic radioactivity, while the second does not. The two models have been designed in order to provide similar sensitivities, in terms of count rate performance and scatter fraction, in the linear range of activities. In addition, the model with the 176Lu intrinsic radioactivity, has been validated in terms of background count rate. Different acquisition schemes have been examined in order to determine the optimum conditions to minimize the 176Lu effects, while maintaining a high trues count rate. In addition, the effect on the image quality, in terms of spatial resolution, signal-to-noise ratio, and minimum detectable activity, was investigated. Results: Both models are in good agreement with the measured data. While, the presence of the 176Lu altered the dead time of the model, it also affected the singles, trues, and randoms count rates. The noise equivalent count rate curves of the two models indicate that for low activities, the lack of 176Lu radioactivity leads to better noise properties due to the underestimation of the randoms. Signal-to-noise ratio measurement on coincidence images confirm the aforementioned claim, since the model without the 176Lu provides better less noisy images. Furthermore, the spatial resolution and the minimum detectable activity are overestimated. Conclusions: It has been proven that the lack of the 176Lu intrinsic radioactivity has an impact on the design of the simulation model's dead time. Even if there is an alignment with experimental results still the noise properties, for a wide range of activities, are overestimated. In addition, for low activities, better image quality, is presented, mainly due to the lack of the 176Lu photons which blur the images. Furthermore, it was shown that the use of a high hardware threshold allows the application of a wide energy window, which improves the statistics without a significant compromise on the quality of the detected photons, mainly, due to the early rejection of the low energy photons and the low scatter factor. [ABSTRACT FROM AUTHOR]

A new method for the determination of radiostrontium in seawater samples has been developed at the Savannah River National Laboratory (SRNL) that allows rapid pre-concentration and separation of strontium and yttrium isotopes in seawater samples for measurement. The new SRNL method employs a novel and effective pre-concentration step that utilizes a blend of calcium phosphate with iron hydroxide to collect both strontium and yttrium rapidly from the seawater matrix with enhanced chemical yields. The pre-concentration steps, in combination with rapid Sr Resin and DGA Resin cartridge separation options using vacuum box technology, allow seawater samples up to 10 L to be analyzed. The total Sr + Sr activity may be determined by gas flow proportional counting and recounted after ingrowth of Y to differentiate Sr from Sr. Gas flow proportional counting provides a lower method detection limit than liquid scintillation or Cerenkov counting and allows simultaneous counting of samples. Simultaneous counting allows for longer count times and lower method detection limits without handling very large aliquots of seawater. Seawater samples up to 6 L may be analyzed using Sr Resin for Sr and Sr with a minimum detectable activity (MDA) of 1-10 mBq/L, depending on count times. Seawater samples up to 10 L may be analyzed for Sr using a DGA Resin method via collection and purification of Y only. If Sr and other fission products are present, then Y (beta energy 1.55 MeV, 58.5 day half-life) is also likely to be present. Y interferes with attempts to collect Y directly from the seawater sample without initial purification of Sr isotopes first and Y ingrowth. The DGA Resin option can be used to determine Sr, and if Y is also present, an ingrowth option with using DGA Resin again to collect Y can be performed. An MDA for Sr of <1 mBq/L for an 8 h count may be obtained using 10 L seawater sample aliquots. [ABSTRACT FROM AUTHOR]