Abstract Evaluation of osteoporotic vertebral fracture risk is currently based on measurement of bone mineral density (BMD), but bone strength depends also on bone quality parameters. Aim of this ...study was to evaluate the validity of a new vertebral morphometric index, the Anterior Vertebral Heights sum (AHs) in discriminating women at high risk of vertebral fracture, comparing its diagnostic accuracy with that of BMD measured at lumbar spine (LS-BMD) and femoral neck (FN-BMD). Materials and methods A total of 163 Caucasian post-menopausal women (age range 46–74 years, mean age ± SD = 63.8 ± 7.1 years), who did not present prevalent fractures at baseline evaluation, were observed at longitudinal follow-up. X-ray of the thoracic and lumbar spine, LS-BMD and FN-BMD measurements were obtained in all patients at baseline and repeated at the second follow-up visit 18–24 months later (mean 21 ± 1.7 months). Radiographs of spine were analysed in order to identify vertebral fractures using a visual semiquantitative method (SQ) and vertebral morphometry as well as by calculating the AHs morphometric index. Results During follow-up, 21/163 patients (12.9%) sustained a new vertebral fracture; 95.2% (20/21) of fractured patients but only 4.9% (7/142) of non-fractured women had reduced AHs values. As regarding BMD, 66.6% (14/21) and 61.9% (13/21) of women with incident fracture were osteoporotic at lumbar spine and femoral neck baseline evaluation , whereas among non-fractured women, 38% (54/142) at LS-BMD and 33.1% (47/142) at FN-BMD were osteoporotic . Analyses of Receiver Operating Characteristic (ROC) curves showed that AHs discriminated vertebral fractures almost perfectly (AUC 0.97; 95% CI 0.95–0.99). On the other hand, the AUC for LS-BMD was only 0.73 (95% CI 0.64–0.81) and for FN-BMD was 0.72 (95%CI 0.63–0.80), showing that the diagnostic accuracy of AHs was significantly higher compared to that of LS-BMD ( p < 0.001) or FN-BMD ( p < 0.001). A modified Poisson regression model for binary data was used to assess the independent role of AHs in predicting vertebral fracture. The effect of AHs remained statistically significant ( p < 0.001) after adjusting by FN-BMD, age, weight and body height. Conclusions Results of this study indicate the validity of this new morphometric index in evaluating the risk of osteoporotic vertebral fractures thus suggesting that AHs should be considered a valid parameter in clinical practice to assess the need for primary prevention of vertebral fractures.
This paper compares the numerical results obtained from various nuclear codes and nuclear data libraries with the YALINA Booster subcritical assembly (Minsk, Belarus) experimental results. This ...subcritical assembly was constructed to study the physics and the operation of accelerator-driven subcritical systems (ADS) for transmuting the light water reactors (LWR) spent nuclear fuel. The YALINA Booster facility has been accurately modeled, with no material homogenization, by the Monte Carlo codes MCNPX (MCNP/MCB) and MONK. The MONK geometrical model matches that of MCNPX. The assembly has also been analyzed by the deterministic code ERANOS. In addition, the differences between the effective neutron multiplication factor and the source multiplication factors have been examined by alternative calculational methodologies. The analyses include the delayed neutron fraction, prompt neutron lifetime, generation time, neutron flux profiles, and spectra in various experimental channels. The accuracy of the numerical models has been enhanced by accounting for all material impurities and the actual density of the polyethylene material used in the assembly (the latter value was obtained by dividing the total weight of the polyethylene by its volume in the numerical model). There is good agreement between the results from MONK, MCNPX, and ERANOS. The ERANOS results show small differences relative to the other results because of material homogenization and the energy and angle discretizations.The MCNPX results match the experimental measurements of the
3He(n,p) reaction rates obtained with the californium neutron source.
In the frame of a US-DOE sponsored project, ANL, BNL, INL and LANL have performed a joint multidisciplinary research activity in order to explore the combined use of integral experiments and ...covariance data with the objective to both give quantitative indications on possible improvements of the ENDF evaluated data files and to reduce at the same time crucial reactor design parameter uncertainties. Methods that have been developed in the last four decades for the purposes indicated above have been improved by some new developments that benefited also by continuous exchanges with international groups working in similar areas. The major new developments that allowed significant progress are to be found in several specific domains: a) new science-based covariance data; b) integral experiment covariance data assessment and improved experiment analysis, e.g., of sample irradiation experiments; c) sensitivity analysis, where several improvements were necessary despite the generally good understanding of these techniques, e.g., to account for fission spectrum sensitivity; d) a critical approach to the analysis of statistical adjustments performance, both a priori and a posteriori; e) generalization of the assimilation method, now applied for the first time not only to multigroup cross sections data but also to nuclear model parameters (the “consistent” method).
This article describes the major results obtained in each of these areas; a large scale nuclear data adjustment, based on the use of approximately one hundred high-accuracy integral experiments, will be reported along with a significant example of the application of the new “consistent” method of data assimilation.
The current pandemic caused by COVID-19 is the biggest challenge for national health systems for a century. While most medical resources are allocated to treat COVID-19 patients, several non-COVID-19 ...medical emergencies still need to be treated, including vertebral fractures and spinal cord compression. The aim of this paper is to report the early experience and an organizational protocol for emergency spinal surgery currently being used in a large metropolitan area by an integrated team of orthopaedic surgeons and neurosurgeons.
An organizational model is presented based on case centralization in hub hospitals and early management of surgical cases to reduce hospital stay. Data from all the patients admitted for emergency spinal surgery from the beginning of the outbreak were prospectively collected and compared to data from patients admitted for the same reason in the same time span in the previous year, and treated by the same integrated team.
A total of 19 patients (11 males and eight females, with a mean age of 49.9 years (14 to 83)) were admitted either for vertebral fracture or spinal cord compression in a 19-day period, compared to the ten admitted in the previous year. No COVID-19 patients were treated. The mean time between admission and surgery was 1.7 days, significantly lower than 6.8 days the previous year (p < 0.001).
The structural organization and the management protocol we describe allowed us to reduce the time to surgery and ultimately hospital stay, thereby maximizing the already stretched medical resources available. We hope that our early experience can be of value to the medical communities that will soon be in the same emergency situation. Cite this article:
2020;102-B(6):671-676.
The MUSE-4 program is a series of zero-power experiments carried out at the Commissariat à l'Energie Atomique Cadarache MASURCA nuclear facility from 2001 to 2004 to study the neutronics of ...accelerator-driven systems (ADSs). The program has investigated the coupling of a multiplying medium to neutron sources of 2.6 or 14 MeV provided by an accelerator (GENEPI) via D(d,n)
3
He or T(d,n)
4
He nuclear fusion reactions, respectively. The fuel was UO
2
-PuO
2
, the simulated coolant was sodium or lead, and the multiplication factor k
eff
ranged from 1 to 0.95. The aim of the experiment was to develop new measurement techniques specific to ADSs and to test the performances of neutronic calculations codes for such systems.
The interpretation of the MUSE-4 experiment has shown that the physical parameters of the system are globally well reproduced by calculations performed with the ERANOS code system, which proves good agreement with both the measurements and the reference Monte Carlo calculations; this concerns the critical mass, the delayed neutron fraction, the fission rate shapes, and the spectral indices. This is a particularly remarkable issue for ERANOS and its associated libraries, which had never been tested for such situations.
Concerning the nuclear data, JEF-based cross sections provide a better agreement on critical mass than other libraries. A sensitivity of several measured parameters to the elastic and inelastic cross section of lead have been demonstrated, and possible biases on these cross sections have been indicated.
We have shown that several methods based on deterministic or stochastic calculations allow us to relate the experimental neutron population decay after a source pulse with the reactivity of the system; these reactivity determination techniques are in good agreement with standard reactivity measurement techniques.
The Working Party on International Nuclear Data Evaluation Cooperation (WPEC) of the Nuclear Science Committee under the Nuclear Energy Agency (NEA/OECD) established a Subgroup (called “Subgroup 33”) ...in 2009 on “Methods and issues for the combined use of integral experiments and covariance data.” The first stage was devoted to producing the description of different adjustment methodologies and assessing their merits. A detailed document related to this first stage has been issued. Nine leading organizations (often with a long and recognized expertise in the field) have contributed: ANL, CEA, INL, IPPE, JAEA, JSI, NRG, IRSN and ORNL. In the second stage a practical benchmark exercise was defined in order to test the reliability of the nuclear data adjustment methodology. A comparison of the results obtained by the participants and major lessons learned in the exercise are discussed in the present paper that summarizes individual contributions which often include several original developments not reported separately.
The paper provides the analysis of the most important results of the adjustment of the main nuclear data of 11 major isotopes in a 33-group energy structure. This benchmark exercise was based on a set of 20 well defined integral parameters from 7 fast assembly experiments. The exercise showed that using a common shared set of integral experiments but different starting evaluated libraries and/or different covariance matrices, there is a good convergence of trends for adjustments. Moreover, a significant reduction of the original uncertainties is often observed. Using the a–posteriori covariance data, there is a strong reduction of the uncertainties of integral parameters for reference reactor designs, mainly due to the new correlations in the a–posteriori covariance matrix. Furthermore, criteria have been proposed and applied to verify the consistency of differential and integral data used in the adjustment. Finally, recommendations are given for an appropriate use of sensitivity analysis methods and indications for future work are provided.
The aims of this paper were to evaluate the clinical relevance of lymphoscintigraphy with intraoperative gamma-probe detection in identifying sentinel nodes (SNs) and to study the prognostic value of ...SN biopsy in head and neck melanoma patients.
Sixty-one patients had lymphoscintigraphy with intradermal injections of 99mTc-Nanocoll (40 MBq), 24 h before surgery. Tumor-positive SNs patients underwent total lymph node dissection. Postoperative histological examination was performed. Patients were followed up for 1 to 5 years (median 3 years). The tumor relapses and the overall survival were evaluated by means of statistical methods.
Lymphoscintigraphy showed lymphatic distribution to more than one basin in 45 patients (74%), in 15 patients one basin was visualized and no basin in 1 patient. In 41 patients the SN was negative for metastases, while in 20 was positive. In a high percentage of patients (30%), metastatic involvement occurred in more than one lymph node basin. During follow-up in the negative SN group, 40 patients remained disease free and 1 relapsed. In the positive SN group, 10 patients remained disease free and 10 relapsed. Recurrence time ranged from 6 to 11 months. The overall survival of the SNs negative group was significantly higher than the positive SN group.
This approach was able to distinguish: a) patients with tumor-negative SNs with a favorable clinical course (98% did not relapse, P<0.001); b) patients with tumor-positive SNs with a high rate of tumor relapse (50%, P<0.001). Therefore SN biopsy may give information about prognosis in head and neck melanoma patients.
One of the most reliable experimental methods for measuring the subcriticality level of a nuclear fuel assembly is the Sjöstrand method applied to the reaction rate generated from a pulsed neutron ...source. This study developed a new analytical methodology simulating the Sjöstrand method, which allows comparing the experimental and analytical reaction rates and the obtained subcriticality levels. In this methodology, the reaction rate is calculated due to a single neutron pulse using MCNP/MCNPX computer code or any other neutron transport code that explicitly simulates the delayed fission neutrons. The calculation simulates a single neutron pulse over a long time period until the delayed neutron contribution to the reaction rate is vanished. The obtained reaction rate is then superimposed to itself, with respect to the time, to simulate the repeated pulse operation until the asymptotic level of the reaction rate, set by the delayed neutrons, is achieved. The superimposition of the pulse to itself was calculated by a simple C computer program. A parallel version of the C program is used due to the large amount of data being processed, e.g. by the Message Passing Interface (MPI). The analytical results of this new calculation methodology have shown an excellent agreement with the experimental data available from the YALINA-Booster facility of Belarus. This methodology can be used to calculate Bell and Glasstone spatial correction factor.
The relevance of selected experiments to specific GNEP target systems is investigated with the use of representativity methods. In this approach, the similarity between the target system and selected ...experiments in connection with a response parameter of interest is quantitatively evaluated by comparing the sensitivity profiles of the response parameter with respect to the nuclear data in the two systems, filtered by the estimated covariance data.
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