The operation of an ionization chamber with depleted gas for radioactivity measurement: Calibration procedure and utilising normalized manufacturer's radionuclide factors.

At the National Metrology Institute of South Africa (NMISA) absolute activity measurements of γ-emitting radionuclides are maintained for longevity on a secondary standard ionization chamber. Because the ionization chamber has lower gas pressure than that normally produced by the manufacturer, this paper focuses attention on explaining a normalization scheme devised to allow NMISA to make use of the manufacturer's supplied radionuclide calibration factors when necessary. The applicability of the procedure is justified through analysis of some results from a comprehensive simulation of the chamber undertaken in an independent study. Comparisons of the derived normalized calibration factors against those obtained through measurement at NMISA are made for a variety of radionuclides.

Activity determination of 18F using liquid scintillation beta-efficiency extrapolation and non-extrapolation methods.

The absolute activity of 18F was determined using 4πß-γ liquid scintillation coincidence counting using beta-efficiency extrapolation. An ionization chamber factor was determined for use during a SIRTI comparison, for which results are presented. A non-extrapolation method based on a detection efficiency analysis was also employed using an adaptation of the double-phototube coincidence efficiency for a threshold above the second monopeak. Results and uncertainty budgets for the two methods are presented and discussed.

Can computed tomographic angiography accurately exclude digestive tract injury after penetrating cervical trauma?

BACKGROUND: Multislice computed tomographic angiography (MCTA) has become the method of choice to screen for arterial injury in penetrating cervical trauma (PCT). There is, however, limited knowledge on its accuracy in terms of digestive tract injury (DTI). Currently, our unit liberally employs both computed tomographic angiography (CTA) and contrast swallow for platysma breaching penetrating neck injuries. This study aimed to determine the accuracy of specific computed tomography findings in the diagnosis of DTI after PCT. METHODS: This was a retrospective review of all consecutive patients with PCT who had undergone MCTA that presented at a single, tertiary, high-volume trauma centre from January 2013 until December 2015. Blinded radiological review of 140 MCTA investigations (33 in the injury group and 107 in the control group) was performed in order to calculate the diagnostic accuracy of trajectory, air, and conventional MCTA signs in the diagnosis of DTI after PCT. RESULTS: Over the study period, 906 patients presenting with PCT had undergone MCTA and a total of 33 patients (3.6%) had confirmed DTI on aggregate gold standard of diagnosis. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of MCTA for detecting DTI was 100%, 65.4%, 47.1%, and 100%, respectively. No injuries were missed on MCTA. CONCLUSION: Our findings suggest that DTI can be safely excluded by means of careful assessment of specific signs on CTA in patients presenting after PCT, obviating the need for further investigation.

Metabolic surgery in South Africa: an initial academic hospital experience.

BACKGROUND: In South Africa, 42.0% of adult females and 13.5% of adult males are classified as obese, the highest recorded numbers in Sub-Saharan Africa. Metabolic surgery has been proven to be a safe and effective treatment, yet due to demand on government resources has only been performed to a limited extent in public hospitals. The aim of this study was to describe the safety and efficacy of performing metabolic surgery at a single academic hospital in South Africa. METHOD: This was a single centre retrospective review of 57 metabolic surgery procedures performed from October 2011 to September 2017 at Tygerberg Hospital, Cape Town, South Africa. The primary outcome was safety including mortality and adverse events. Secondary outcomes included effect of surgery on weight and diabetes resolution. RESULTS: A total of 57 patients underwent laparoscopic metabolic surgery, of which 44 (83.0%) were female with a mean age (standard deviation) of 42.8 (8.0) years. Fifty-six patients (98%) underwent Roux-and-Y gastric bypass and one (2%) had a sleeve gastrectomy performed. There were no mortalities and overall morbidity was 14.0%, with 3 (5.3%) classified as major and 5 (8.8%) as minor. The follow-up rate at 1 year was 100%. Mean preoperative body mass index (BMI) was 58.8 kg/m2, and comorbidities included hypertension (59.6%), Type 2 Diabetes (42.1%), and dyslipidaemia (36.8%). There were no conversions to open surgery and at one year the mean (95% confidence interval) percentage excess body mass index loss was 50.4% (44.0-56.8%). CONCLUSION: Metabolic surgery can be performed safely in the public sector in South Africa, with short-term safety and efficacy outcomes comparable to international reports. Larger scale studies are needed to determine long-term outcomes and cost-effectiveness.

Absolute standardizations of 99mTc and 57Co by 4π electron-gamma liquid scintillation coincidence counting for SIRTI and SIR comparisons.

The radionuclides 99mTc and 57Co were standardized via absolute liquid scintillation counting techniques. We provide the first technical report on the absolute standardization of 99mTc using 4π(LS)e-γ coincidence counting. The low detection efficiency of low-energy conversion electrons translates into a large efficiency extrapolation range. A simulation indicated that the γ-ray interacting with the liquid scintillator introduces curvature to the count rate vs. efficiency relationship, the approximation of the functional form used for extrapolation providing the main measurement uncertainty for 99mTc. A detection efficiency analysis for both radionuclides is presented. Results from the standardizations, and SIRTI and SIR comparison exercises are reported.

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.

Activity determination of (59)Fe by 4π beta-gamma counting using liquid scintillation in the beta channel.

This paper reports on absolute activity measurements of iron-59 made at the National Metrology Institute of South Africa (NMISA) via 4π(LS)ß-γ coincidence counting. The exercise formed part of an Asia Pacific Metrology Program (APMP) regional key comparison. Source data were analysed by the extrapolation technique for a number of gamma-ray window settings. In addition, a feasibility study was undertaken on a second technique; a non-extrapolation method based on a detection efficiency analysis. The reported activity concentration of the (59)Fe solution was determined with a relative uncertainty of 0.28% (k=1), the uncertainty being due mainly to the rate vs. efficiency fitting process. The result from the non-extrapolation method was lower than that given by extrapolation by 0.33%, within two standard deviations. Possible reasons for the small discrepancy are discussed.

Standardization of Tc-99 by three liquid scintillation counting methods.

The NMISA participated in the international key comparison of the pure beta-emitter Technetium-99, CCRI(II)-K2.Tc-99. The comparison solution was standardized using three methods, namely the TDCR efficiency calculation method, the CIEMAT/NIST efficiency tracing method and the 4π(LS)ß-γ coincidence tracing method with Co-60 as tracer. Excellent agreement between results obtained with the three methods confirmed the applicability of the beta spectral shape given by the latest (2011) DDEP evaluation of Tc-99 decay data, rather than the earlier (2004) evaluation.

Nurses' scope of practice and the implication for quality nursing care.

PURPOSE: This article provides an overview of the implications for patients' health status and care needs when assessments are performed by nurses not licensed or competent to perform this task. The Waterlow scale (Judy Waterlow, The Nook, Stroke Road, Henlade, TAUNTON, TA3 5LX) scenario is used as a practice example to illustrate this case. ORGANIZATIONAL CONSTRUCT: The international nursing regulatory bodies, in South Africa called the South African Nursing Council, set the scope of practice wherein nurses are allowed to practice. Different categories of nurses are allowed to practice according to specified competencies, in alignment with their scope of practice. METHODS: A retrospective quantitative study was utilized. A checklist was used to perform an audit on a random sample of 157 out of an accessible population of 849 patient files. Data were gathered in May 2012, and the analysis was done using frequencies and percentages for categorical data. Reliability and validity were ensured, and all ethical principles were adhered to. FINDINGS: Eighty percent of risk assessments were performed by nurses not licensed or enrolled to perform this task unsupervised. Areas such as tissue malnutrition, neurological deficits, and medication were inaccurately scored, resulting in 50% of the Waterlow risk-assessment scales, as an example, being incorrectly interpreted. This has implications for quality nursing care and might put the patient and the institution at risk. CONCLUSIONS: Lower-category nurses and student nurses should be allowed to perform only tasks within their scope of practice for which they are licensed or enrolled. Nurses with limited formal theoretical training are not adequately prepared to perform tasks unsupervised, even in the current global nursing shortage scenario. CLINICAL RELEVANCE: To optimize and ensure safe and quality patient care, risk assessments should be done by a registered professional nurse, who will then coordinate the nursing care of the patient with the assistance of the lower category of nurses.

Effect of a worksite wellness programme on the physical work capacity profile of workers in an electricity supply company

The aim of this study was to determine the effect of a worksite wellness programme on the physical work capacity profile of workers. Male workers who did not meet the minimum physical ability task requirement based on an assessment of ten essential physical abilities for their job were selected for this study. Twelve workers in the experimental group participated in a 24-month worksite wellness programme and 62 were in the control group. Pre- and post-tests determined if their physical work capacity profile met the minimum physical ability task requirements of their job. There was no practically significant (d = 0.8) difference between the two groups before the start of the programme after controlling for age; gender; motivation to change and initial physical work capacity profile differences. The results showed that workers whose physical work capacity profile did not meet the minimum physical ability task requirement of their job; were practically significantly (.......... = 4.25) more likely to improve their physical work capacity profile through the 24-month worksite wellness programme to a level were they met the minimum physical ability task requirement of the job; than those receiving no intervention. The study found that the cases were poorly reported. The follow up system at the local level between local government officials and the farmers was not efficient for the prevention of agrichemical poisonings. The contributory factors were insufficient information and training; the incorrect use of personal protective equipment; the lack of safety of the agri-chemical store; and the absence of a monitoring system on the majority of farms. This study demonstrated that the notification of agricultural chemical poisoning was applied in a fragmentary manner between the different governmental levels and departments

First participation by the NMISA in a low-level comparison: CCRI(II)-S9 exercise.

The NMISA Radioactivity Standards Laboratory participated in the CCRI(II)-S9 inter-comparison of the measurement of the activity concentration of (137)Cs and (40)K in rice material, piloted by the KRISS. The paper describes the equipment used, the measurement set-up and data analysis. The efficiency of the detector for (137)Cs and (40)K was determined by comparison against a spiked standard solution, and Monte Carlo simulations performed to estimate the difference in γ-ray escape probability between the solution standard and starch (as an approximation for milled rice) due to attenuation disparities. The uncertainty budget was estimated rather conservatively, since these were the first low-level measurements performed by the NMISA using an HPGe detector.

Results of an international comparison for the activity measurement of 177Lu.

An international Key Comparison of (177)Lu has recently been carried out. Twelve laboratories performed assays for radioactivity content on aliquots of a common master solution of (177)Lu, leading to eleven results submitted for entry into the Key Comparison Database of the Mutual Recognition Arrangement. A proposed Comparison Reference Value (CRV) was calculated to be 3.288(4)MBq/g using all eleven results. Degrees of equivalence and their uncertainties were calculated for each laboratory based on the CRV. Most of the values reported by the participating laboratories were within 0.6% of the CRV.

Accurate activity measurement of Lu-177 by the liquid scintillation 4πß-γ coincidence counting technique.

This paper reports on absolute measurements made at the NMISA by the 4π[LS]ß-γ coincidence extrapolation technique, which formed part of a key comparison of activity measurements of the radionuclide lutetium-177, a beta-gamma emitter. A detection efficiency analysis based on the decay scheme indicated that the coincidence extrapolation method is feasible for extracting the source disintegration rate of (177)Lu. A simulation was undertaken utilizing the efficiency equations to give an indication of the expected variation of the source count rate with efficiency for different gamma-ray windows. Both the simulation and experiment indicated that the window giving the highest counting efficiency was centered about the 208.4 keV photopeak, with the data showing linear variation in the upper efficiency range. The extracted activity concentration of the (177)Lu solution proved to be highly accurate, being higher than the proposed comparison reference value by 0.15%, well within one standard uncertainty (σ=0.26%) as specified by the NMISA.

Absolute standardization of 241Pu by the TDCR technique and effect of the beta spectral shape.

The NMISA participated in the 2010 international key comparison of (241)Pu, standardizing the inter-comparison solution by the TDCR efficiency calculation technique. Special attention was paid to ensure accurate efficiency calculation for this low-energy, pure beta-emitter: in particular the effect of low-energy stopping powers on the calculation of ionization quenching was assessed and an optimal value for the quench parameter, kB, was determined. In addition, phototube efficiency mismatch was accounted for by a software minimization technique. The effect of the beta spectral shape on the activity extracted from data analysis was assessed and found to be significant. Based on the results of this work we propose a new value for the average beta-particle energy.

Modification of a commercial atomic force microscopy for low-noise, high-resolution frequency-modulation imaging in liquid environment.

A key issue for high-resolution frequency-modulation atomic force microscopy imaging in liquids is minimizing the frequency noise, which requires a detailed analysis of the corresponding noise contributions. In this paper, we present a detailed description for modifying a commercial atomic force microscope (Bruker MultiMode V with Nanoscope V controller), aiming at atomic-resolution frequency-modulation imaging in ambient and in liquid environment. Care was taken to maintain the AFMs original stability and ease of operation. The new system builds upon an optimized light source, a new photodiode and an entirely new amplifier. Moreover, we introduce a home-built liquid cell and sample holder as well as a temperature-stabilized isolation chamber dedicated to low-noise imaging in liquids. The success of these modifications is measured by the reduction in the deflection sensor noise density from initially 100 fm/√Hz to around 10 fm/√Hz after modification. The performance of our instrument is demonstrated by atomically resolved images of calcite taken under liquid conditions.

Performance review of large scale up-flow anaerobic sludge blanket sewage treatment plants.

This article evaluates the performance of 10 large scale upflow anaerobic sludge blanket (UASB) sewage treatment plants (STP) located in semi-tropical areas, 7 plants were located in Brazil, 2 in India and 1 in the Middle East. In addition to the UASB, essential functional units of the STP which potentially impact on the UASB are also evaluated. Most grit removal systems were performing adequately, however in one plant very little grit was being removed. This could have serious implications for the performance of the plant as in a relatively short period of time the reactors could become full of grit. The performance results obtained in this study (COD, BOD and TSS removal efficiencies) are compared to the results of recent literature publications and also to the results of some early pilot and full scale studies. The results found here are broadly similar to those result reported in the recent literature but show a lower performance in comparison with the early pilot scale plants. Factors such as improper design, poor operating procedures, insufficient maintenance and the presence of high sulphate concentrations have been identified as the main reasons for the lower performance.

Enhancement of nasal and intestinal calcitonin delivery by the novel Pheroid fatty acid based delivery system, and by N-trimethyl chitosan chloride.

Therapeutic peptides are highly potent and specific in their functions, but difficulties in their administration require parallel development of viable delivery systems to improve their bioavailability. In this study the potential of a novel lipid-based colloidal delivery system for improving the absorption of nasally and intestinally administered salmon calcitonin (sCT) was investigated. Two types of delivery vehicles based on Pheroid technology was prepared and characterized. Liposome-like bilayer vesicles had a mean diameter of 1.0 microm and microsponges were 1.6 microm. Doses of 10 IU/kg and 500 IU/kg bodyweight sCT were administered intranasally and intestinally to rats, respectively. The obtained absorption enhancement with Pheroid vesicles and Pheroid microsponges were also compared with the absorption enhancement obtained with N-trimethyl chitosan chloride (TMC). With the inclusion of 0.5% (w/v) TMC the maximum plasma concentration (C(max)) of sCT increased from 72.6+/-6.1 pg/ml to 478.5+/-6.1 pg/ml after nasal administration. Pheroid vesicles and Pheroid microsponges increased the C(max) values of sCT to 262.64+/-17.1 pg/ml and 202.66+/-28.6 pg/ml, respectively. The time to reach the maximum concentration (T(max)) was also significantly decreased from 35 min to approximately 14 min. Intestinal administration of Pheroid formulations increased the C(max) of sCT from 249.1+/-21.5 pg/ml to 386.2+/-45.5 and 432.1+/-18.9 pg/ml, respectively for Pheroid vesicles and Pheroid microsponges. TMC increased the C(max) of sCT to 738.9+/-277.1 pg/ml. TMC and Pheroid technology could offer the potential to significantly improve intranasal and intestinal absorption of sCT and reduce the variability in absorption.

ETFAD/EADV eczema task force 2009 position paper on diagnosis and treatment of atopic dermatitis.

BACKGROUND: The diagnosis of atopic dermatitis (AD) is made using evaluated clinical criteria. Management of AD must consider the symptomatic variability of the disease. METHODS: EADV eczema task force developed its guideline for atopic dermatitis diagnosis and treatment based on literature review and repeated consenting group discussions. RESULTS AND DISCUSSION: Basic therapy relies on hydrating topical treatment and avoidance of specific and unspecific provocation factors. Anti-inflammatory treatment based on topical glucocorticosteroids and topical calcineurin antagonists is used for exacerbation management and more recently for proactive therapy in selected cases. Topical corticosteroids remain the mainstay of therapy, but the topical calcineurin inhibitors, tacrolimus and pimecrolimus are preferred in certain locations. Systemic anti-inflammatory treatment is an option for severe refractory cases. Microbial colonization and superinfection may induce disease exacerbation and can justify additional antimicrobial/antiseptic treatment. Systemic antihistamines (H1) can relieve pruritus, but do not have sufficient effect on eczema. Adjuvant therapy includes UV irradiation preferably of UVA1 wavelength or UVB 311 nm. Dietary recommendations should be specific and given only in diagnosed individual food allergy. Allergen-specific immunotherapy to aeroallergens may be useful in selected cases. Stress-induced exacerbations may make psychosomatic counselling recommendable. 'Eczema school' educational programmes have been proven to be helpful.

Fe-55 activity measurements at the NMISA revisited.

Twenty years ago South Africa's Radioactivity Standards Laboratory (now operated by the NMISA) was the first to measure the activity of (55)Fe by combining the triple-to-double coincidence ratio (TDCR) liquid scintillation method with theoretical efficiency formulae. The extracted activity was however found to be consistently low by about 6%. Due to improvements in both the counting system and analysis technique, it was decided to re-examine the method as applied at the NMISA. The latest results are presented and discussed, particularly with regard to a quantitative study into which vial type is better suited to obtaining accurate (55)Fe activity measurements.

Improvement of a dynamic scanning force microscope for highest resolution imaging in ultrahigh vacuum.

We report on a modification of a commercial scanning force microscope (Omicron UHV AFM/STM) operated in noncontact mode (NC-AFM) at room temperature in ultrahigh vacuum yielding a decrease in the spectral noise density from 2757 to 272 fm/Hz. The major part of the noise reduction is achieved by an exchange of the originally installed light emitting diode by a laser diode placed outside the vacuum, where the light is coupled into the ultrahigh vacuum chamber via an optical fiber. The setup is further improved by the use of preamplifiers having a bandpass characteristics tailored to the cantilever resonance frequency. The enhanced signal to noise ratio is demonstrated by a comparison of atomic resolution images on CeO(2)(111) obtained before and after the modification.