Results of an international comparison of activity measurements of 68Ge

An international key comparison, identifier CCRI(II)-K2.Ge-68, has been performed. The National Institute of Standards and Technology (NIST) served as the pilot laboratory, distributing aliquots of a 68Ge/68Ga solution. Results for the activity concentration, CA, of 68Ge at a reference date of 12h00 UTC 14 November 2014 were submitted by 17 laboratories, encompassing many variants of coincidence methods and liquid-scintillation counting methods. The first use of 4π(Cherenkov)β-γ coincidence and anticoincidence methods in an international comparison is reported. One participant reported results by secondary methods only. Two results, both utilizing pure liquid-scintillation methods, were identified as outliers. Evaluation using the Power-Moderated Mean method results in a proposed Comparison Reference Value (CRV) of 621.7(11)kBqg-1, based on 14 results. The degrees of equivalence and their associated uncertainties are evaluated for each participant. Several participants submitted 3.6mL ampoules to the BIPM to link the comparison to the International Reference System (SIR) which may lead to the evaluation of a Key Comparison Reference Value and associated degrees of equivalence.

Assessing the fitness-for-purpose of satellite multi-mission ocean color climate data records: A protocol applied to OC-CCI chlorophyll-a data

In this work, trend estimates are used as indicators to compare the multi-annual variability of different satellite chlorophyll-a (Chla) data and to assess the fitness-for-purpose of multi-mission Chla products as climate data records (CDR). Under the assumption that single-mission products are free from spurious temporal artifacts and can be used as benchmark time series, multi-mission CDRs should reproduce the main trend patterns observed by single-mission series when computed over their respective periods. This study introduces and applies quantitative metrics to compare trend distributions from different data records. First, contingency matrices compare the trend diagnostics associated with two satellite products when expressed in binary categories such as existence, significance and signs of trends. Contingency matrices can be further summarized by metrics such as Cohen's κ index that rates the overall agreement between the two distributions of diagnostics. A more quantitative measure of the discrepancies between trends is provided by the distributions of differences between trend slopes. Thirdly, maps of the level of significance P of a t-test quantifying the degree to which two trend estimates differ provide a statistical, spatially-resolved, evaluation. The proposed methodology is applied to the multi-mission Ocean Colour-Climate Change Initiative (OC-CCI) Chla data. The agreement between trend distributions associated with OC-CCI data and single-mission products usually appears as good as when single-mission products are compared. As the period of analysis is extended beyond 2012 to 2015, the level of agreement tends to be degraded, which might be at least partly due to the aging of the MODIS sensor on-board Aqua. On the other hand, the trends displayed by the OC-CCI series over the short period 2012-2015 are very consistent with those observed with VIIRS. These results overall suggest that the OC-CCI Chla data can be used for multi-annual time series analysis (including trend detection), but with some caution required if recent years are included, particularly in the central tropical Pacific. The study also recalls the challenges associated with creating a multi-mission ocean color data record suitable for climate research.

Development and psychometric properties of the Psychological Therapies Outcome Scale - Intellectual Disabilities (PTOS-ID)

BACKGROUND

There are few valid and reliable psychological therapy outcome measures available for use with people with intellectual disabilities (ID). The current study involved the development of a new scale; the Psychological Therapies Outcome Scale - Intellectual Disabilities (PTOS-ID), and the examination of its validity and internal consistency.

METHOD

The PTOS-ID was administered to 175 people who have ID accessing specialist ID services. The construct validity of the scale was investigated through exploratory factor analysis, concurrent validity through comparison with the Brief Symptom Inventory and internal reliability through internal consistency analysis.

RESULTS

Three factors emerged from the principal components analysis with high levels of internal consistency: (1) anger and mood (α = 0.82); (2) positive well-being (α = 0.81); and (3) anxiety (α = 0.76). Factors (1) and (2) were combined to measure psychological distress (α = 0.85), which correlated strongly with the Global Severity Index of the Brief Symptom Inventory (r = 0.85).

CONCLUSIONS

This preliminary study suggests that the PTOS-ID is a psychometrically robust measure of psychological distress and psychological well-being that can be used with people with ID. Further research is required to assess its reliability and ability to detect change.

Evidence against solar influence on nuclear decay constants

The hypothesis that proximity to the Sun causes variation of decay constants at permille level has been tested and disproved. Repeated activity measurements of mono-radionuclide sources were performed over periods from 200 days up to four decades at 14 laboratories across the globe. Residuals from the exponential nuclear decay curves were inspected for annual oscillations. Systematic deviations from a purely exponential decay curve differ from one data set to another and are attributable to instabilities in the instrumentation and measurement conditions. The most stable activity measurements of alpha, beta-minus, electron capture, and beta-plus decaying sources set an upper limit of 0.0006% to 0.008% to the amplitude of annual oscillations in the decay rate. Oscillations in phase with Earth's orbital distance to the Sun could not be observed within a 10^-6 to 10^-5 range of precision. There are also no apparent modulations over periods of weeks or months. Consequently, there is no indication of a natural impediment against sub-permille accuracy in half-life determinations, renormalisation of activity to a distant reference date, application of nuclear dating for archaeology, geo- and cosmochronology, nor in establishing the SI unit becquerel and seeking international equivalence of activity standards.

Attitudes towards prenatal HIV testing and treatment among pregnant women in southern India

During June and July 1999, oral interviews were conducted on 666 women seeking prenatal care at 9 medical facilities in Chennai and Mysore, India, to assess their attitudes towards prenatal HIV testing and antiretroviral prophylaxis for preventing perinatal HIV transmission if needed. Seventy-eight per cent were aware of the risk of perinatal HIV transmission and 36% knew that intervention could reduce the chances of such transmission. Eighty-six per cent would agree to undergo prenatal HIV testing but only 21% of all respondents would make this decision independently while 46% said their husband would have to decide. Of those women who would not agree to testing, 21% would agree if testing were compulsory. Ninety-seven per cent of respondents would undergo antiretroviral prophylaxis to prevent vertical transmission, and 94% would consider alternatives to breastfeeding if HIV positive. Considering its widespread acceptability, prenatal voluntary counselling and testing may be an affordable method of HIV prevention for this population.

Aortic Aneurysm Morphology for Planning Endovascular Aortic Grafts: Limitations of Conventional Imaging Methods

Purpose:

To test whether conventional computed tomography scanning (CT) and contrast aortography (CA) provide adequate data for planning endovascular aortic grafting by measuring 33 parameters in patients having both imaging examinations for evaluation of abdominal aortic aneurysms (AAA).

Methods:

Fifty consecutive patients with AAA (41 men, 9 women; average age 65 years) had CT and CA (mean 26 days between exams). The data collected and analyzed included: 8 sites of diameter, 4 lengths, 6 angles, and 15 other dimensional measurements.

Results:

Conflicts between CA and CT data were common. Eighteen patients appeared to have a distal cuff by CA but not by CT. Proximal neck length could not be assessed by CT in 5 and had a difference between CA and CT > 1 cm in 25 patients. CA overestimated neck length in 11 patients. Common iliac artery angulation > 60° occurred unilaterally in 27 patients and bilaterally in 5. Seven patients had both iliac aneurysm and > 60° iliac angulation. Thirteen patients had one or more iliac aneurysms (> 2 cm) shown by CT but not by CA.

Conclusions:

For endovascular graft planning: (1) more detailed measurement is required than for traditional surgery; and (2) conventional CT and CA are complementary imaging studies, but each has important limitations.

Radiosynthesis, In Vivo Biological Evaluation, and Imaging of Brain Lesions with [123I]-CLINME, a New SPECT Tracer for the Translocator Protein

The high affinity translocator protein (TSPO) ligand 6-chloro-2-(4'-iodophenyl)-3-(N,N-methylethyl)imidazo[1,2-a]pyridine-3-acetamide (CLINME) was radiolabelled with iodine-123 and assessed for its sensitivity for the TSPO in rodents. Moreover neuroinflammatory changes on a unilateral excitotoxic lesion rat model were detected using SPECT imaging. [(123)I]-CLINME was prepared in 70-80% radiochemical yield. The uptake of [(123)I]-CLINME was evaluated in rats by biodistribution, competition, and metabolite studies. The unilateral excitotoxic lesion was performed by injection of α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid unilaterally into the striatum. The striatum lesion was confirmed and correlated with TSPO expression in astrocytes and activated microglia by immunohistochemistry and autoradiography. In vivo studies with [(123)I]-CLINME indicated a biodistribution pattern consistent with TPSO distribution and the competition studies with PK11195 and Ro 5-4864 showed that [(123)I]-CLINME is selective for this site. The metabolite study showed that the extractable radioactivity was unchanged [(123)I]-CLINME in organs which expresses TSPO. SPECT/CT imaging on the unilateral excitotoxic lesion indicated that the mean ratio uptake in striatum (lesion:nonlesion) was 2.2. Moreover, TSPO changes observed by SPECT imaging were confirmed by immunofluorescence, immunochemistry, and autoradiography. These results indicated that [(123)I]-CLINME is a promising candidate for the quantification and visualization of TPSO expression in activated astroglia using SPECT.