A superconducting transformer system for high current cable testing

This article describes the development of a direct-current (dc) superconducting transformer system for the high current test of superconducting cables. The transformer consists of a core-free 10,464 turn primary solenoid which is enclosed by a 6.5 turn secondary. The transformer is designed to deliver a 50 kA dc secondary current at a dc primary current of about 50 A. The secondary current is measured inductively using two toroidal-wound Rogowski coils. The Rogowski coil signal is digitally integrated, resulting in a voltage signal that is proportional to the secondary current. This voltage signal is used to control the secondary current using a feedback loop which automatically compensates for resistive losses in the splices to the superconducting cable samples that are connected to the secondary. The system has been commissioned up to 28 kA secondary current. The reproducibility in the secondary current measurement is better than 0.05% for the relevant current range up to 25 kA. The drift in the secondary current, which results from drift in the digital integrator, is estimated to be below 0.5 A/min. The system's performance is further demonstrated through a voltage-current measurement on a superconducting cable sample at 11 T background magnetic field. The superconducting transformer system enables fast, high resolution, economic, and safe tests of the critical current of superconducting cable samples.

Neoadjuvant therapy of gastric cancer with cetuximab added to both irinotecan and cisplatin, followed by surgical resection and adjuvant chemoradiation

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Background: We previously demonstrated the efficacy of irinotecan (CPT) and cisplatin (Cis) combination therapy as neoadjuvant therapy for locally advanced gastric cancer [Newman E et al. J Gastrointest Surg. 2002.]. This trial was designed to add cetuximab (C) to both induction treatment and adjuvant chemoradiation (CRT) with bolus 5-FU/LV. Methods: Pts with untreated locally advanced (T3, T4 or N+) gastric/GE cancers were eligible. Neoadjuvant therapy consisted of Cis 25mg/m2 + CPT 75mg/m2 on d1,8 q21d x 4, C 400mg/m2 on d1, then 250mg/m2 qwk. Curative (R0) resection was performed 4–6 wks later. Adjuvant CRT with 5-FU/LV (425/20/m2 qd x 5 on wks 1,14,19; 400/20/m2 qd x 4 on wk 5, x 3 on wk 9) was given with C 250mg/m2 qwk. Results: Since 11/05, 21 pts [median age 59 (32–82); 9 Caucasian, 11 Asian, 1 Hispanic; 15 male, 20 PS 0–1] received neoadjuvant therapy. The most common toxicities were gr 3 neutropenia (38%), gr 2 rash (33%), gr 2 fatigue (29%); gr 4 included 1 pt each of diarrhea, neutropenia, & hypomagnesemia. 3 did not complete neoadjuvant therapy, due to gr 3 rash, diarrhea and GI bleeding (2 had gastrectomy; 1 lost to f/u). All 18 pts who completed neoadjuvant therapy were surgically explored. 4 had occult metastases, and went off study. 14 underwent R0 gastrectomy (see table); 8 were downstaged, 2 had stable disease, 4 were upstaged compared to the preoperative EUS. There was no postoperative mortality. Of 14 resected pts, 2 did not receive adjuvant therapy (prolonged postoperative recovery), 1 too early to assess, and 11 remaining receiving CRT. The most common toxicities for CRT were gr 3 nausea, gr 3 emesis, gr 2 and 3 fatigue, 3 pts each and 1 each of gr 4 neutropenia and thrombocytopenia. Among the 18 pts who completed neoadjuvant therapy, 5 died of disease, 1 is alive with disease, 12 remain NED with median f/u of 11.6mos (4.1–27.7mos). Conclusions: The addition of C to CPT/Cis as neoadjuvant therapy and to postoperative adjuvant CRT is well tolerated. The regimen induces a favorable pathologic response on the primary tumor. Ongoing evaluation includes K-ras mutation status on outcome and survival benefit. [Supported in part by a grant from BMS.]

[Table: see text]

Uncertainties in internal doses calculated for Mayak workers--a study of 63 cases

This study makes use of 63 cases of Mayak workers exposed to Pu-239 with autopsy data and some late-time urine bioassay data. In addition, air-concentration data--used to construct monthly average values--are available for each case, which provide the time dependence and potential magnitudes of normal inhalation intakes for each case. The purpose of the study is to develop and test Bayesian methods of dose calculation for the Mayak workers. The first part of the study was to quantitatively characterise the uncertainties of the bioassay data. Then, starting with three different published biokinetic models, the data are fit by varying intake and model perturbation parameters, e.g., parameters influencing the lung, thoracic lymph nodes, liver and bone retention. Statistical self-consistency arguments are used to check the measurement uncertainty parameters within the Poisson-lognormal model. The second part of the study is to set up and test Bayesian dose calculations, which use the point determinations of biokinetic parameters from the study cases within a discrete, empirical Bayes approximation. The main conclusion of the study is that these methods are now ready to be applied to the entire Mayak worker population.

EFFECTS OF LOW NEIGHBOURHOOD SOCIOECONOMIC STATUS ON INFLAMMATION, OXIDATIVE STRESS, AND RISK OF MORTALITY IN PATIENTS WITH CORONARY ARTERY DISEASE

Background: Socioeconomicstatus (SES) is an influential determinant of prognosis in coronary artery disease (CAD). Patient neighbourhood SES may contribute to CAD outcomes, beyond effects of personal SES. Methods: Following 485 CAD patients for > 10 years, we examine the effect of neighbourhood income, education, and unemployment on survival, and investigate relationships between SES and markers of inflammation and oxidative stress. Results: SES was associated significantly with risk of mortality, however this relationship was not observed for cardiovascular death. Each one quintile decrease in income, education, and employment was associated with a 32%, 40% and 45% greater risk of non-cardiovascular mortality, respectively. Inflammatory and oxidative stress markers correlate with income, but do not diminish associations between neighbourhood SES and mortality. Conclusions: Significant disparities in non-cardiovascular mortality related to neighbourhood SES were observed in this study, which argues for greater attention to socioeconomic factors in chronic disease prevention and health care delivery. C.L.H. is supported bya Providence Health Research Institute & Canadian Institutes of HealthResearch MD/PhD Studentship Award, and a Michael Smith Foundation for HealthResearch Trainee Award. (colour figure available in PDF version)

IMPDOS (improved dosimetry and risk assessment for plutonium-induced diseases): internal dosimetry software tools developed for the Mayak worker study

A collection of software tools developed for the Mayak worker study is described. IMPDOS is software for modelling, data analysis, and activity and dose calculations using the bioassay and postmortem data from Mayak workers provided by Southern Urals Biophysics Institute. The capabilities include: parameter fitting of data for individual cases, Bayesian dose calculations using the fit results for collections of cases with extensive data as a biokinetic prior, and database storage of results for retrieval, analysis and interpretation.

An empirical multivariate log-normal distribution representing uncertainty of biokinetic parameters for 137Cs

A simplified biokinetic model for (137)Cs has six parameters representing transfer of material to and from various compartments. Using a Bayesian analysis, the joint probability distribution of these six parameters is determined empirically for two cases with quite a lot of bioassay data. The distribution is found to be a multivariate log-normal. Correlations between different parameters are obtained. The method utilises a fairly large number of pre-determined forward biokinetic calculations, whose results are stored in interpolation tables. Four different methods to sample the multidimensional parameter space with a limited number of samples are investigated: random, stratified, Latin Hypercube sampling with a uniform distribution of parameters and importance sampling using a lognormal distribution that approximates the posterior distribution. The importance sampling method gives much smaller sampling uncertainty. No sampling method-dependent differences are perceptible for the uniform distribution methods.

A study of early Los Alamos internal exposures to plutonium

Internal dose caused by exposure to (239)Pu/(240)Pu is calculated for a group of 210 former Los Alamos workers who participated in the urine bioassay programme during the years 1944-45. An iterative Bayesian procedure is employed, where the distribution of intake amounts resulting from an initial calculation is used to define a prior probability distribution of inhalation intakes for an iterated second calculation. The urine bioassay data from this time period were not of high quality, and the more accurate intake prior tempers the effect of spurious high samples, which were probably caused by sample contamination.

Internal dosimetry verification and validation database

Simulated-data internal dosimetry cases for use in intercomparison exercises or as a software verification and validation tool have been published on the internet (www.lanl.gov/bayesian/software Bayesian software package II). A user may validate their internal dosimetry code or method using this simulated bioassay data. Or, the user may choose to try out the Los Alamos National Laboratory codes ID and UF, which are also supplied. A Poisson-lognormal model of data uncertainty is assumed. A collection of different possible models for each nuclide (e.g. solubility types and particle sizes) are used. For example, for 238Pu, 14 different biokinetic models or types (8 inhalation, 4 wound and 2 ingestion) are assumed. Simulated data are generated for all the assumed biokinetic models, both for incidents, where the time of intake is known, and for non-incidents, where it is not. For the dose calculations, the route of intake, but not the biokinetic model, is considered to be known. The object is to correctly calculate the known true dose from simulated data covering a period of time. A 'correct' result has been defined in two ways: (1) that the credible limits of the calculated dose include the correct dose and (2) that the calculated dose is within a factor of 2 of the correct dose.

Bayesian hypothesis testing-use in interpretation of measurements

Bayesian hypothesis testing may be used to qualitatively interpret a dataset as indicating something "detected" or not. Hypothesis testing is shown to be equivalent to testing the posterior distribution for positive true amounts by redefining the prior to be a mixture of the original prior and a delta-function component at 0 representing the null hypothesis that nothing is truly present. The hypothesis-testing interpretation of the data is based on the posterior probability of the usual modeling hypothesis relative to the null hypothesis. Real numerical examples are given and discussed, including the distribution of the non-null hypothesis probability over 4,000 internal dosimetry cases. Currently used comparable methods based on classical statistics are discussed.

Comparison of dose estimation from occupational exposure to 239Pu using different modelling approaches

Several approaches are available for bioassay interpretation when assigning Pu doses to Mayak workers. First, a conventional approach is to apply ICRP models per se. An alternative method involves individualised fitting of bioassay data using Bayesian statistical methods. A third approach is to develop an independent dosimetry system for Mayak workers by adapting ICRP models using a dataset of available bioassay measurements for this population. Thus, a dataset of 42 former Mayak workers, who died of non-radiation effects, with both urine bioassay and post-mortem tissue data was used to test these three approaches. All three approaches proved to be adequate for bioassay and tissue interpretation, and thus for Pu dose reconstruction purposes. However, large discrepancies are observed in the resulting quantitative dose estimates. These discrepancies can, in large part, be explained by differences in the interpretation of Pu behaviour in the lungs in the context of ICRP lung model. Thus, a careful validation of Pu lung dosimetry model is needed in Mayak worker dosimetry systems.

Gallbladder carcinoma

Although it is the most common cancer of the biliary tree, gallbladder carcinoma remains an uncommon disease. As a result, many clinicians rarely encounter it and there is uncertainty regarding proper management. Resection is the most effective and only potentially curative treatment. Early stage tumors are often curable with a proper resection; however, many patients present late in the course of the disease when surgical intervention is no longer effective. While other treatment modalities are used in patients with advanced disease, there is limited data on efficacy. In many cases, the diagnosis is made after a cholecystectomy has been performed and an incidental tumor is identified in the specimen. In such cases, reoperation and definitive resection is appropriate and effective for patients with invasive lesions.

Internal dose assessment data management system for a large population of Pu workers

This paper describes the design and implementation of the Los Alamos National Laboratory (LANL) dose assessment (DA) data system. Dose calculations for the most important radionuclides at LANL, namely plutonium, americium, uranium and tritium, are performed through the Microsoft Access DA database. DA includes specially developed forms and macros that perform a variety of tasks, such as retrieving bioassay data, launching the FORTRAN internal dosimetry applications and displaying dose results in the form of text summaries and plots. The DA software involves the following major processes: (1) downloading of bioassay data from a remote data source, (2) editing local and remote databases, (3) setting up and carrying out internal dose calculations using the UF code or the ID code, (3) importing results of the dose calculations into local results databases, (4) producing a secondary database of 'official results' and (5) automatically creating and e-mailing reports. The software also provides summary status and reports of the pending DAs, which are useful for managing the cases in process.

Myelination as assessed by conventional MR imaging is normal in young children with idiopathic developmental delay

BACKGROUND AND PURPOSE

A common isolated reported finding in brain imaging studies on developmentally delayed children is delayed myelination. We hypothesized that brain MR imaging scans of these children would show delayed subcortical myelination of white matter with specific involvement of the subcortical U-fibers as these represent terminal zones of myelination and are the last areas to myelinate.

MATERIALS AND METHODS

A total of 93 children (31 controls, 62 with idiopathic developmental delay [IDD]) aged 17 to 46 months were identified on the basis of having brain MR imaging for evaluation of IDD (cases) or for another condition (controls). Children with diseases that primarily affect white matter or overt intracranial lesions or malformations were excluded. IDD was defined as psychomotor retardation without a clear cause on the basis of history, physical, genetic, metabolic, and neuroimaging examinations. Developmental quotients (DQs) were calculated for all children with IDD on the basis of clinical history, examination, and psychometric testing. Three board-certified pediatric neuroradiologists examined axial T2-weighted brain images and used a published scoring system to rate the extent of myelination in the frontal, temporal, parietal, and peritrigonal brain regions. In addition, subcortical U-fibers in the frontal, temporal, and parietal lobes were scored separately. Data were analyzed at both the intraobserver and interobserver levels, and scores were compared between groups and tested for interactions with age and DQ.

RESULTS

There were no differences in the timing or extent of myelination in the control and IDD groups at any age in any brain region. In the IDD group, there was no relationship between myelination scores and DQ or developmental domain.

CONCLUSIONS

Our findings did not support the hypothesis that there is a correlation between IDD and the maturity of myelination, including the terminal zones, as seen on conventional brain MR imaging. Neuroimaging evaluation of maturity of subcortical myelination is not a marker of IDD in young children, and the isolated "finding" of delayed myelination should be interpreted with caution.