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The main purpose of identifying and locating the retina vessels is to specify from the fundus image the various tissues of the vascular structure, which can be wide or tight. The classification of vessels in the retinal image often confronts several challenges, such as the low contrast accompanying the fundus image, the inhomogeneity of the background lighting, and the noise. Moreover, fuzzy c-means (FCM) is one of the most frequently used algorithms for medical image segmentation due to its effectiveness. Hence, many FCM method derivatives have been developed to improve their noise robustness and time-consuming. This paper aims to analyze the performance of some improved FCM algorithms to recommend the best ones for the segmentation of retinal blood vessels. Eight derivatives of FCM algorithm are detained in this study: FCM, EnFCM, SFCM, FGFCM, FRFCM, DSFCM_N, FCM_SICM and SSFCA. The performance analysis is conducted from three viewpoints: noise robustness, blood vessels segmentation performance, and time-consuming. At first, the noise robustness of improved FCM clustering algorithms is evaluated using a synthetic image degraded by various types and levels of noise. Then, the ability of the selected algorithms to segment retinal blood vessels is assessed based on images from the DRIVE and STARE databases after a pre-processing phase. Finally, the time consumption of each algorithm is measured. The experiments demonstrate that the FRFCM and DSFCM_N algorithms achieve better results in terms of noise robustness and blood vessels segmentation. Regarding the running time, the FRFCM algorithm requires less time than other algorithms in the segmentation of retinal images. The results of this study are extensively discussed, and some suggestions are proposed at the end of this paper. [ABSTRACT FROM AUTHOR]

To improve the parameters of reactors and reduce the cost of generated electricity, we carry out research aimed at determining the most rational use of fuel. Different methods use different mathematical and physical models, which leads to some difference in the obtained data. One of these methods is the profiling of fuel assemblies. In this paper, we present the theory used in modeling and calculations by the Serpent 2 software package, consider methods of axial profiling of compositions in a reactor, and provide a comparison of the obtained results and substantiation of their reliability at an intermediate stage of the study. [ABSTRACT FROM AUTHOR]

Longitudinal qualitative research can provide rich understanding of the life circumstances of vulnerable groups who experience health inequities, of whether, how and why these circumstances change, and of how these circumstances and processes of change impact health. But, this rich understanding is not automatic and requires systematic and thoughtful approaches to data collection and analysis. The purpose of this paper is to describe two longitudinal qualitative studies embedded in mixed-methods studies of social determinants of HIV in the United States and the Dominican Republic. We compare these two studies to critically reflect on specific techniques that facilitate longitudinal and iterative data collection, management, and analysis, in particular the use of participant-specific matrices and analytic summaries across the distinct phases of the research. We conclude that combining cross-sectional and longitudinal analysis that engages with both themes and processes of change can contribute to improved contextualization and understanding of social determinants of HIV. [ABSTRACT FROM AUTHOR]

Plutonium metal exchange programs operated by the Rocky Flats Plant were conducted from 1956–1989 to ensure quality and to compare measurements in a plutonium metal matrix. Los Alamos National Laboratory (LANL) re-established the program in 2001 to assess the quality of analytical chemistry capabilities that support special nuclear material characterization. It is the only program of its kind for the preparation and distribution of plutonium metal reference materials with a range of impurity contents to multiple laboratories for destructive measurements of elemental concentration, isotopic abundance, and both metallic and non-metallic impurity levels. This program provides independent verification of analytical measurement capabilities for each of the seven currently participating laboratories, and allows any technical problems with analytical measurements to be identified and corrected. This paper focuses on basic program elements and presents a summary of methods and results for plutonium, uranium, neptunium, and americium, measurements. [ABSTRACT FROM AUTHOR]

As there is a rising demand on energy efficiency the proper network stack is an essential for every wireless sensor network application. This paper gives a comprehensive view on performance comparison of $$\hbox {Atmel}^{\circledR }$$ Lightweight Mesh (LWM) and ZigBee Pro technology based on extensive real measurements. We focused mainly on application layer throughput, routing latency and self-healing capability. Although the LWM clearly outperforms ZigBee Pro in most aspects, the LWM has particular drawbacks. Particularly, the LWM provides smaller footprint and faster stack processing along with higher application throughput. The most notable throughput difference where the LWM outperforms the BitCloud was by as much as thirteen times. [ABSTRACT FROM AUTHOR]

The paper investigates quantitative differences in the signal characteristics of ventricular fibrillation (VF) and other cardiac arrhythmias. The analysis procedure comprises two steps: calculation of a short-term autocorrelation function (ACF) followed by a regression test on a plot of peak magnitudes of the ACF against lag values (the ACF/lag plot). We detect VF by testing the hypothesis that the ACF/lag plot of VF does not pass a linear regression test. Analysis of 31 separate episodes (of VF and other ventricular arrhythmias), each comprising three successive segments of 1·5s each produced the following results: (1) 100 per cent sensitivity (Se), 62 per cent specificity (Sp) and 74 per cent test efficiency (TE) after analysis of the first segment; (2) 100 per cent Se, 86 per cent Sp and 90 per cent TE after the second segment; and (3) 100 per cent Se, 100 per cent Sp and 100 per cent TE after the third segment. This method quantifies the notion that VF signals are nonperiodic with a random amplitude distribution, whereas ventricular tachycardia (VT) signals are usually periodic with more uniform amplitude distributions. Accurate discrimination and identification of VF can be very important in intensive-care settings, as well as in the design of automatic cardioverters and defibrillators. [ABSTRACT FROM AUTHOR]

Background: Proton magnetic resonance spectroscopy (MRS) measures concentrations of metabolites in vivo and provides a powerful method for identifying tumours. MRS has not entered routine clinical use partly due to the difficulty of analysing the spectra.Objective: To create a straightforward method for interpreting short-echo-time MRS of childhood cerebellar tumours.Materials and Methods: Single-voxel MRS (1.5-T Siemens Symphony NUM4, TR/TE 1,500/30 ms) was performed at presentation in 30 children with cerebellar tumours. The MRS results were analysed for comparison with histological diagnosis. Peak heights for N-acetyl aspartate (NAA), creatine (Cr), choline (Cho) and myo-inositol (mIns) were determined and receiver operator characteristic curves used to select ratios that best discriminated between the tumour types. The method was implemented by a group of clinicians and scientists, blinded to the results.Results: A total of 27 MRS studies met the quality control criteria. NAA/Cr >4.0 distinguished all but one of the astrocytomas from the other tumours. A combination of Cr/Cho <0.75 and mIns/NAA <2.1 separated all the medulloblastomas from the ependymomas.Conclusion: Peak height ratios from short-echo-time MRS can accurately predict the histopathology of childhood cerebellar tumours. [ABSTRACT FROM AUTHOR]

Background: Evaluation of technical skill is notoriously difficult because of the subjectivity and time-consuming expert analysis. No ongoing evaluation scheme exists to assess the continuing competency of surgeons. This study examined whether surgeons' self-assessment accurately reflects their actual surgical technique.Methods: Hierarchical task analysis (HTA) of laparoscopic cholecystectomy was constructed. Ten expert surgeons were asked to modify the HTA for their own technique. The HTAs of these surgeons then were compared with their actual operations, which had been recorded and assessed by two observers.Results: A total of 40 operations were assessed. All the gallbladders subjected to surgery were classified as grades 1 to 3. The mean interrater reliability for the two observers had a k value of 0.84 (p < 0.05), and the mean intrarater reliability between surgeons and observers had a k value of 0.79 (p < 0.05).Conclusions: Surgeons' self-evaluation is accurate for technical skills aspects of their operations. This study demonstrates that self-appraisal using HTA is feasible, accurate, and practical. The authors aim to increase the numbers in their study and also to recruit residents. [ABSTRACT FROM AUTHOR]

The aim of the study was to evaluate a new method for automated definition of a center lumen line in vessels in cardiovascular image data. This method, called VAMPIRE, is based on improved detection of vessel-like structures. A multiobserver evaluation study was conducted involving 40 tracings in clinical CTA data of carotid arteries to compare VAMPIRE with an established technique. This comparison showed that VAMPIRE yields considerably more successful tracings and improved handling of stenosis, calcifications, multiple vessels, and nearby bone structures. We conclude that VAMPIRE is highly suitable for automated definition of center lumen lines in vessels in cardiovascular image data. [ABSTRACT FROM AUTHOR]

The electrolarynx provides a valuable means of verbal communication for people who cannot use their natural voice-production mechanism, but technology has changed very little since it was introduced in the 1950s. The presence of background noise degrades the resulting speech. In this study' background noise was reduced by a new method, independent component analysis-based adaptive noise cancelling, which can remove noise components of the primary input signal based on statistical independence, by incorporating both second-order and higherorder statistics. The method shows better performance than the conventional least mean square algorithm. Acoustic analysis of the denoised electrolarynx speech revealed a significant reduction in the amount of background noise. Results from the perceptual evaluations indicated that the new filtering technique produced a noticeable improvement in the acceptability of the electrolarynx speech in a quiet environment (from 1.75 to 2.49, arbitrary units) or a noisy environment (from 0.59 to 1.82). In general, there was no significant improvement or degradation in intelligibility in the quiet environment (from 52.7 to 53.3). However, the processing did improve the intelligibility in a babble-noise environment (from 24.9 to 40.6). The improvement in acceptability and intelligibility may increase the communication ability of the user in daily situations. [ABSTRACT FROM AUTHOR]