IDEAS internal contamination database: a compilation of published internal contamination cases. A tool for the internal dosimetry community

In the scope of the IDEAS project to develop General Guidelines for the Assessment of Internal Dose from Monitoring data, two databases were compiled. The IDEAS Bibliography database contains references dealing with problems related to cases of internal contamination. The IDEAS Internal Contamination Database now contains more than 200 cases of internal contamination. In the near future, the IDEAS Internal Contamination database will be made available to the internal dosimetry community. The database has several potential applications, including: training, testing biokinetic models, testing software for calculating intakes and doses from bioassay data, comparison of data from a new accidental intake with that from previous exposures to similar materials. The database is by no means complete, and this presentation is also an appeal for internal contamination cases to extend and update it.     

A methodology for auto-monitoring of internal contamination by 131I in nuclear medicine workers

The manipulation of 131I in Nuclear Medicine involves significant risks of internal contamination of the staff. In the event of an accidental contamination, or when the Radiological Protection Program includes routine individual monitoring of internal contamination, it is necessary to implement internal dose estimation through in vivo and in vitro bioassay techniques. Due to the huge extension of the Brazilian country, this type of monitoring becomes unfeasible if all measurements have to be performed at the institutes of the CNEN. Thus, if the Nuclear Medicine Centres (NMC) become able to conduct the monitoring of their employees, this skill would be of great significance. The methodology proposed in this work consists in a simple and inexpensive protocol for auto-monitoring the internal contamination by 131I, using the resources available at the NMC. In order to verify the influence of the phantom in the calibration factor for the measurement of 131I in thyroid, it was performed a comparison among a variety of phantoms commercially available, including the Neck-Thyroid Phantom developed in IRD. A protocol for performing in vivo and in vitro measurements by the NMC was established. The applicability of the individual monitoring techniques was also evaluated by comparing the detection limits with the derived limits associated with the annual dose limits for workers.     

The fatigue strength of internal threads in three materials

Repeated tension fatigue tests have been carried out on $\text{3}\text{4}\text{?16}$ UNF internally threaded specimens in a 60:40 brass, a normalized En 8 steel and a hardened and tempered En 26 steel. Ground threads did not give as high a fatigue strength as tapped threads, despite having a better root form; this is attributed to beneficial cold working effects in thread tapping. Increasing the outside diameter of the specimen from 1.4 to 1.7D, where D is the nominal thread diameter, did not increase in cross-sectional area. Despite having nearly double the static strength of the En 8 specimens with ground threads. A wide range of endurance has been covered and the results contribute to design data in an area where few such data exist.     

Interdialytic weight gain and ultrafiltration rate in hemodialysis: Lessons about fluid adherence from a national registry of clinical practice

Excessive interdialytic weight gain (IWG) and ultrafiltration rates (UFR) above 10 mL/h/kg body weight imply higher morbidity and mortality. This study aimed to estimate the prevalence of high fluid consumers, describe UFR patterns, and describe patient characteristics associated with IWG and UFR. The Swedish Dialysis DataBase and The Swedish Renal Registry of Active Treatment of Uremia were used as data sources. Data were analyzed from patients aged ≥18 on regular treatment with hemodialysis (HD) and registered during 2002 to 2006. Interdialytic weight gain and dialytic UFR were examined in annual cohorts and the records were based on 9693 HD sessions in 4498 patients. Differences in proportions were analyzed with the chi-square test and differences in means were tested using the ANOVA or the t test. About 30% of the patients had IWG that exceed 3.5% of dry body weight and 5% had IWG ≥5.7%. The volume removed during HD was >10 mL/h/kg for 15% to 23% of the patients, and this rate increased during the first dialytic year. Patient characteristics associated with fluid overload were younger age, lower body mass index, longer dialytic vintage, and high blood pressure. By studying IWG and dialytic UFR as quality indicators, it is shown that there is a potential for continuing improvement in the care of patients in HD settings, i.e., to enhanced adherence to fluid restriction or alternatively to extend the frequency of dialysis for all patients, e.g., by providing daily treatment.     

Individual monitoring of internal exposure for nuclear medicine workers in Switzerland

Monitoring of internal exposure for nuclear medicine workers requires frequent measurements due to the short physical half-lives of most radionuclides used in this field. The aim of this study was to develop screening measurements performed at the workplace by local staff using standard laboratory instrumentation, to detect whether potential intake has occurred. Such measurements do not enable to determine the committed effective dose, but are adequate to verify that a given threshold is not exceeded. For radioiodine, i.e. (123)I, (124)I, (125)I and (131)I, a calibrated surface contamination monitor is placed in front of the thyroid to detect whether the activity threshold has been exceeded. For radionuclides with very short physical half-lives (≤ 6 h), such as (99m)Tc and those used in positron emission tomography imaging, i.e. (11)C, (15)O, (18)F and (68)Ga, screening procedures consist in performing daily measurements of the ambient dose rate in front of the abdomen. Other gamma emitters used for imaging, i.e. (67)Ga, (111)In and (201)Tl, are measured with a scintillation detector located in front of the thorax. For pure beta emitters, i.e. (90)Y and (169)Er, as well as beta emitters with low-intensity gamma rays, i.e. (153)Sm, (177)Lu, (186)Re and (188)Re, the procedure consists in measuring hand contamination immediately after use. In Switzerland, screening procedures have been adopted by most nuclear medicine services since such measurements enable an acceptable monitoring while taking into account practical and economic considerations.     

Failure of a furnace outlet pipe in a benzene plant by internal oxidation due to improper welding practice

A furnace outlet pipe made of INCOLOY^® alloy 800H to handle gaseous hydrocarbon in a benzene plant developed cracks in the weld heat-affected zone during operation at 595 °C. Microstructural characterization revealed that the cracks were of the ductile intergranular mode, which could be related to localized plastic deformation alongside the grain boundaries. The microstructure of the heat-affected zone was distinguished from the base metal by a coarser grain structure and intergranular oxidation in addition to higher hardness indicating the presence of residual stresses from the welding process. Intergranular oxidation was found to result in a mixture of Cr and Fe oxides enveloping a Ni-rich solid-solution adjacent to the grain boundary. Therefore, the observed ductile intergranular cracking could be related to localized plastic deformation in the relatively “soft” zone of Ni-rich solid-solution. Most evidence indicated that the failure occurred because of improper welding atmosphere leading to internal oxidation under relatively low oxygen potential, which is oxidizing to Cr and to a lesser extent Fe, and reducing to Ni.     

Keeping baby safe: A randomized trial of a parent training program for infant and toddler motor vehicle injury prevention

Motor vehicle crashes are responsible for much death and disability among infants and toddlers. This study evaluated Keeping Baby Safe In and Around the Car, a multimedia DVD designed to improve knowledge about car seat installation among parents of infants and toddlers. The randomized controlled trial was conducted with 195 parents of children aged 0–24 months. Effective car seat use was evaluated via a written knowledge quiz and car seat simulation. Results from analyses of covariance models show that posttest scores for the intervention condition were significantly higher than those of the control condition on both knowledge and car seat simulation measures. The results, consistent across outcome measures and regardless of child age, suggest that viewing the Keeping Baby Safe In and Around the Car DVD resulted in significant gains in parents’ car seat knowledge and their ability to discriminate the critical elements of correct car seat installation. Dissemination of engaging multimedia DVDs such as this program might reduce motor vehicle crash-related injuries to infants and toddlers.     

Uremic hyperhomocysteinemia: a randomized trial of folate treatment for the prevention of cardiovascular events

Homocysteine is a risk factor for atherosclerosis in the general population, and serum homocysteine levels are almost universally elevated in chronic renal failure patients. When such patients are treated with dialysis, cardiovascular disease accounts for more than 50% of their mortality, which, in some proportion, may be pathophysiologically related to the elevated serum homocysteine levels. From April 2003 to March 2005, we conducted a 2-year, double-blind, randomized, placebo-controlled trial of 186 patients with end-stage kidney disease due to any cause, who were older than 18 years and stable on hemodialysis. Patients were assigned to receive either oral folic acid 10 mg 3 times a week immediately after every dialysis session under nurse supervision or an identical-appearing placebo for the entire study. On admission, plasma total homocysteine (tHcy) levels were above 13.9 micromol/L in 96.7% of patients (median 25.0 micromol/L, range 9.3-104.0 micromol/L). In the placebo group, tHcy levels remained elevated at 6, 12, and 24 months, while oral folate significantly decreased tHcy to a median value of 10.5 (2.8-20.3) micromol/L, (p<0.01). During the study, 38 patients (folic acid group 17 vs. placebo group 21; p=0.47) died from cardiovascular disease. Kaplan-Meier life table analysis dealing with the incidence of cardiovascular events, both fatal and nonfatal (myocardial infarction, arrhythmias, angina, heart failure, cerebrovascular accident), showed that 2 years of folic acid treatment and the lowering of the homocysteine blood levels had no effect on cardiovascular events (p=0.41; hazard ratio 1.24, 95% CI 0.74-2.10). However, the carotid artery intima-media wall thickness measured in a blinded fashion decreased from 1.94 +/- 0.59 mm to 1.67 +/- 0.38 mm (p<0.01) after 2 years of folate therapy. In this short-term study of uremic patients, 2 years of folic acid supplementation normalized the tHcy blood levels in 92.3% of patients but did not change the incidence of cardiovascular events compared with the control group. However, ultrasonography of the common carotid arteries performed at entry and 24 months later showed a significant decrease in intima-media thickness with folate supplementation. This suggests that early folate supplementation may benefit patients with chronic renal failure by preventing cardiovascular deterioration.     

Study of nuclear medicine practices in Portugal from an internal dosimetry perspective

Nuclear medicine practices involve the handling of a wide range of pharmaceuticals labelled with different radionuclides, for diagnostic and therapeutic purposes. This work intends to evaluate the potential risks of internal contamination of nuclear medicine staff in several Portuguese nuclear medicine services and to conclude about the requirement of a routine internal monitoring. A methodology proposed by the International Atomic Energy Agency (IAEA), providing a set of criteria to determine the need, or not, for an internal monitoring programme, was applied. The evaluation of the risk of internal contaminations in a given set of working conditions is based on the type and amount of radionuclides being handled, as well as the safety conditions with which they are manipulated. The application of the IAEA criteria showed that 73.1% of all the workers included in this study should be integrated in a routine monitoring programme for internal contaminations; more specifically, 100% of workers performing radioimmunoassay techniques should be monitored. This study suggests that a routine monitoring programme for internal exposures should be implemented in Portugal for most nuclear medicine workers.     

The role of correspondence sections in post-publication peer review: A bibliometric study of general and internal medicine journals

Scientific journals claim that correspondence sections are for post-publication peer review. We compared the conditions for submission and the bibliometrics of letters-to-editors published in leading medical journals in 2002 and 2007 using journal-derived information and data from PubMed and Journal Citation Reports. The median time limit for letter submissions decreased from 6 to 3.5 weeks, the median word limit from 400 to 350. The median number of letters per published article was near one in both years. Only about half of the letters were followed by an author reply in either year. Electronic response systems were available for four journals in 2007.     

A longitudinal crack in a cylindrical shell under internal pressure

The study relates to the strength of a cracked shell. Linear thin shell theory is employed to obtain solutions for internal pressure and uniform circumferential bending. A shallow shell approximation is used, and shown valid providing crack length and shell thickness are small enough in comparison with shell radius. Initial formulation as a boundary value problem is shown equivalent to two coupled singular integral equations. These were solved numerically using a computer. Stresses are found to display singularities as inverse square-root of distance from a crack tip, as with the flat plate. The main results are graphs of normal and bending stress singularity strengths against a curvature/crack-length dimensionless parameter.

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Zusammenfassung Diese Arbeit behandelt die Stärke von einer gerissenen Schale. Die lineare Theorie dünner Schalen ist benutzt um dieses Problem für den Innendruck und gleichmäßige Umkreis-biegung zu lösen. Die Annäherungen der mäßig gekrümte Schalen sind benutzt welche zulassig sind nur wenn die Rißlänge und die Dicke der Schale klein sind im Vergleich zu dem Schalradius. Die anfängliche Formelierung als ein Randwertproblem ergibt sich als gleichwertig zwei gekuppelten singulären Integralgleichungen. Diese sind numerisch gelöst mit Hilfe einer Rechenautomat. Die Spannungen zeigen, in Übereinstimmung mit der flachen Platte, umgekehrte Quadratwurzelsingularitäten. Die Resultaten der Stärke der Normal- und Biegung-spannungsingularitäten sind graphisch als Funktion eines dimensionslosen Krümmungs-Rißlängeparameter gegeben.

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Résumé Cette étude est sur la résistance d'une monocque fêlée longitudinalement. À l'aide de la théorie linéare des toques minces élastiques l'on obtient la solution de deux cas: 1) coque sous pression intérieure et 2) flexion circonférentielle uniforme. On fait l'approximation que la coque est de faible profondeur et l'on démontre que les solutions sont valables pourvu que la longeur de la fêlure et l'épaisseur de la coque soient assez petites comparées au rayon de la coque. On formule d'abord un système elliptique des équations aux dérivées partielles, qui se transforme en deux équations intégrales simultanées. Celles-ci sent résolues numériquement à l'aide d'un ordinateur. On trouve que la contrainte possède des singularités proportionelles à l'inverse de la racine carrée de la distance d'une extrémité de la fêlure: ce résultat est identique à celui qui existe pour une plaque. Les résultats principaux que l'on présente sont des courbes de l'amplitude de ces singularités en fonction d'un paramètre charactéristique de la grandeur de la fêlure et du rayon de la coque.

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Notation c half crack length, inch - E Young's modulus of elasticity, psi - h thickness of shell, inch - M _t twisting moment resultant - M circumferential bending moment resultant far from crack - M _x , M _y , M _xy bending and twisting moment resultants - N _x , N _y , N _xy normal and shear stress resultants - p _i internal pressure, psi - p ₀ reference pressure, psi - Q, Q _x , Q _y transverse shear stress resultants - R radius of shell, inch - x, y Cartesian coordinates for shallow shell formulation, inch - w outward radial displacement of cylindrical shell, inch - Euler constant (0.5772...) - dimensionless parameter, ²=[3(1–v ²)/4]^1/2(c ²/Rh) - v Poisson's ratio This work was supported in part by the Office of Naval Research under Contract Nonr 1866(02), in part by the National Aeronautics and Space Administration under Grant NsG-559, and by the Division of Engineering and Applied Physics, Harvard University.     

A comparison of inventory cost reduction strategies in a JIT manufacturing system

Although many companies have found JIT manufacturing to be a very effective manufacturing strategy, few models have been developed which can help direct JIT efforts. This article discusses some of the problems with modelling JIT manufacturing, it describes some simple models of inventory costs in a JIT system and it uses these models to evaluate alternative inventory-cost reduction strategies in a printed circuit board (PCB) assembly system.     

A note on limitations of a certain creep function used in practice

The creep function of Aleksandrovskii, widely used in some parts of the world, is compared to long-range creep test data available in the literature, using computer optimization techniques. It is found that this creep function is inherently incapable of modeling creep for large creep durations and high ages at stress application.

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Résumé La fonction de fluage d'Aleksandrovskii largement utilisée dans certaines parties du monde est confrontée à l'aide des techniques d'optimisation informatisée aux résultats d'essais de fluage à long terme publiés. On établit que cette fonction de fluage ne peut se prêter à une mobilisation pour les études de fluage sur de grands intervalles de temps et sous des sollicitations appliquées à des ages avancés.

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This work has been carried out as part of a project sponsored by the U.S. National Science Foundation under Grant, No. ENG 75-14848 (A 00 and A 01).     

Toward single-calibrant quantification in HPLC. A comparison of three detection strategies: evaporative light scattering, chemiluminescent nitrogen, and proton NMR

There is an urgent need for detection technologies that enable accurate and precise quantification of solutions containing small organic molecules in a manner that is rapid, cheap, non-labor-intensive, readily automated, and without a requirement for specific analyte standards. We provide a theoretical analysis that predicts that the logarithmic nature of the working domain of the evaporative light-scattering detector (ELSD) will normally bias toward underestimation of chromatographically resolved impurities, resulting in an overestimation of analyte purity. This analysis is confirmed by experiments with flow injection analysis (FIA) and gradient reversed-phase high performance liquid chromatography (RP-HPLC). Quantification is further compromised by the dependence of response parameters on the matrix composition and hence on the retention time of the analyte. Attempts were made to ameliorate these problems by using the response surface of a single compound to calibrate throughout the HPLC gradient. A chemiluminescent nitrogen detector (CLND) was also used in a similar manner, and the performance of the two techniques were compared against those of each other and that of a reference standard technique. A protocol for this purpose was developed using proton nuclear magnetic resonance (1H NMR) and the ERETIC method to enable quantification by integrating proton signals. The double-blind comparison exercise confirmed molar nitrogen CLND response to be sufficiently stable and robust across a methanol gradient to be used with a single external nitrogenous calibrant to quantify nitrogen-containing compounds of known molecular formula. The performance of HPLC-CLND was very similar to that of NMR, while that of HPLC-ELSD was seen to be significantly worse, showing it to be unsuitable for the purpose of single-calibrant quantification. We report details and experience of our use of RP-HPLC-CLND-MS to characterize and quantify small amounts of solutions of novel compounds at nominal levels of 10mM in microtiter plate (MTP) format.     

A simplified implementation of a gradient-enhanced damage model with transient length scale effects

Gradient-enhanced damage models with constant gradient activity suffer from spurious damage growth at high deformation levels. This issue was resolved by Geers et al. (Comput Methods Appl Mech Eng 160(1–2):133–153, 1998) by expressing the gradient activity parameter as a function of the local equivalent strain at the expense of adding one set of degrees of freedom to those of the standard model. In this contribution, a new formulation of the gradient-enhanced damage model with variable length scale is presented which eliminates the need for the extra set of degrees of freedom. The merits of the proposed formulation are demonstrated, and the choice of the damage evolution law and its impact on the model performance are discussed.     

A chaotic regime of internal precession in3He-B

We have found a chaotic regime of counter-motion of the normal and superfluid magnetizations in³He-B. It takes place under conditions corresponding to the experiments with catastrophic relaxation. We study a spatially homogeneous regime of the magnetization's precession by employing a numerical simulation of the Leggett-Takagi theory, and show that there is a topological reconstruction of the spin dynamics that brings about a chaotic regime of Arnold diffusion. It is important that the regime, which takes place owing to the sophisticated nature of the Leggett-Takagi equations, does not require an external driving force.     

A new implementation of the Lanczos method in linear problems

The Lanczos algorithm has proved to be a powerful solution method not only for finding the eigenvalues but for solving linear systems of equations. In this work a new implementation of the algorithm is presented for solving linear systems of equations with a sequence of right-hand sides. The versions of the method proposed in the past treat the right-hand side vectors successively by keeping the tridiagonal matrix and the orthonormal basis in fast or secondary storage. The new technique handles all approximations to the solution vectors simultaneously without the necessity for keeping the tridiagonal matrix or the orthonormal basis in fast or secondary storage. Thus, when the first solution vector has converged to a required accuracy good approximations to the remaining solution vectors have simultaneously been obtained. It then takes fewer iterations to reach the final accuracy by working separately on each of the remaining vectors.     

A study of internal stresses produced as a result of lubricated reversing friction

New experimental data on internal stresses produced in steel surface layers as a result of reversing friction in the presence of various lubricants are reported showing that the addition of organic alcohols to oil affects friction and friction-induced internal stresses, and that the use of oleic acid as a lubricant additive destroys the effect of alternating the direction of friction and leads to radical changes in the magnitude and distribution of internal stresses of the first kind.We would like to convey our thanks to Academician P. A. Rebinder and Professor S. Ya. Veiler for their valuable advice and interest in this work.