| 1. |
- Akkoyun, S., et al.
(författare)
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AGATA - Advanced GAmma Tracking Array
- 2012
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Ingår i: Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. - : Elsevier BV. - 0168-9002 .- 0167-5087 .- 1872-9576. ; 668, s. 26-58
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Tidskriftsartikel (refereegranskat)abstract
- The Advanced GAmma Tracking Array (AGATA) is a European project to develop and operate the next generation γ-ray spectrometer. AGATA is based on the technique of γ-ray energy tracking in electrically segmented high-purity germanium crystals. This technique requires the accurate determination of the energy, time and position of every interaction as a γ ray deposits its energy within the detector volume. Reconstruction of the full interaction path results in a detector with very high efficiency and excellent spectral response. The realisation of γ-ray tracking and AGATA is a result of many technical advances. These include the development of encapsulated highly segmented germanium detectors assembled in a triple cluster detector cryostat, an electronics system with fast digital sampling and a data acquisition system to process the data at a high rate. The full characterisation of the crystals was measured and compared with detector- response simulations. This enabled pulse-shape analysis algorithms, to extract energy, time and position, to be employed. In addition, tracking algorithms for event reconstruction were developed. The first phase of AGATA is now complete and operational in its first physics campaign. In the future AGATA will be moved between laboratories in Europe and operated in a series of campaigns to take advantage of the different beams and facilities available to maximise its science output. The paper reviews all the achievements made in the AGATA project including all the necessary infrastructure to operate and support the spectrometer. © 2011 Elsevier B.V. All rights reserved.
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| 2. |
- Avdovic, Pajazit, 1955, et al.
(författare)
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Evaluating the machinability of Inconel 718 using polar diagrams
- 2010
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Ingår i: Proceedings of the ASME Turbo Expo 2010: Power for Land, Sea, and Air, GT 2010, Glasgow, United Kingdom, 14-18 June 2010. - 9780791843963 ; 1, s. 987-996
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Konferensbidrag (refereegranskat)abstract
- The use of a polar diagram method for describing and evaluating the machinability of Inconel 718 was explored. Five key parameters of the work material, representing the mechanical and physical properties which have strongest influence on its machinability, were employed in the diagrams. These five parameters were integrated into a single polar diagram, used to describe the machinability of Inconel 718. Variations in the machinability of Inconel 718 products or components of a given type produced in different batches were analyzed. Industrial experiments were conducted to test the relationship between the polar diagram of the work material, its carbon content, and tool wear of the ceramic cutting tools used in machining it. Work materials of Inconel 718 in which the polar diagrams of machinability were similar in size and shape exhibited very similar behavior during the cutting process. The polar diagram method employed appeared to be useful for selecting suitable cutting data for the machining of new materials.
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| 3. |
- Avdovic, Pajazit, 1955, et al.
(författare)
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Evaluating the Machinability of Inconel 718 Using Polar Diagrams
- 2011
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Ingår i: Journal of Engineering for Gas Turbines and Power. - : ASME International. - 1528-8919 .- 0742-4795. ; 133:7
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Tidskriftsartikel (refereegranskat)abstract
- The use of a polar diagram method for describing and evaluating the machinability of Inconel 718 was explored. Five key parameters of the work material, representing the mechanical and physical properties, which have the strongest influence on its machinability, were employed in the diagrams. These five parameters were integrated into a single polar diagram, used to describe the machinability of Inconel 718. Variations in the machinability of Inconel 718 products or components of a given type produced in different batches were analyzed. Industrial experiments were conducted to test the relationship between the polar diagram of the work material, its carbon content, and the tool wear of the ceramic cutting tools used in machining it. Work materials of Inconel 718 in which the polar diagrams of machinability were similar in size and shape exhibited very similar behavior during the cutting process. The polar diagram method employed appeared to be useful for selecting suitable cutting data for the machining of new materials. [DOI: 10.1115/1.4002679]
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| 4. |
- Bushlya, Volodymyr, et al.
(författare)
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Tool wear mechanisms of PcBN in machining Inconel 718: Analysis across multiple length scale
- 2021
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Ingår i: CIRP Annals - Manufacturing Technology. - : Elsevier BV. - 1726-0604 .- 0007-8506. ; 70:1, s. 73-78
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Tidskriftsartikel (refereegranskat)abstract
- Recently, PcBN tooling have been successfully introduced in machining Ni-based superalloys, yet our knowledge of involved wear mechanisms remains limited. In this study, an in-depth investigation of PcBN tool degradation and related wear mechanisms when machining Inconel 718 was performed. Diffusional dissolution of cBN is an active wear mechanism. At high cutting speed oxidation of cBN becomes equally important. Apart from degradation, tool protection phenomena were also discovered. Oxidation of Inconel 718 resulted in formation of γ-Al2O3 and (Al,Cr,Ti)3O4 spinel that were deposited on the tool rake. Also on the rake, formation of (Ti,Nb,Cr)N takes place due to cBN-workpiece interaction. This creates a sandwich tool protection layer forming continuously as tool wear progresses. Such in operando protection enabled counterbalancing tool wear mechanisms and achieved high performance of PcBN in machining.
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| 5. |
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| 6. |
- Paz-Soldan, C, et al.
(författare)
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Synchrotron and collisional damping effects on runaway electron distributions
- 2016
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Ingår i: 58th Annual Meeting of the APS Division of Plasma Physics. ; 61:18, s. CO4.00010 -
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Validated models of runaway electron (RE) dissipation are required to confidently approve safe ITER Q=10 operation. DIII-D experiments using quiescent REs are exploring the importance of synchrotron and collisional damping terms to RE dissipation. New time and energy-resolved measurements of RE bremsstrahlung hard X-ray (HXR) emission reveal stark differences between high and low energy REs as damping terms are varied. Previously reported anomalously high RE dissipation only applies to low energy REs. At high energy (where synchrotron effects are strongest) low synchrotron damping cases reach higher peak RE energy despite weaker particle confinement. Low-energy RE decay is observed concurrently with high-energy RE growth. RE dissipation models predict bump-on-tail distributions whose properties depend on the damping terms. Measured HXR spectra are very broad, as expected for bump-on-tail distributions.
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| 7. |
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| 8. |
- Pivodic, Aldina, 1978, et al.
(författare)
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Development and validation of a new clinical decision support tool to optimize screening for retinopathy of prematurity
- 2022
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Ingår i: British Journal of Ophthalmology. - : BMJ Publishing Group Ltd. - 0007-1161 .- 1468-2079. ; 106:11, s. 1573-1580
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND/AIMS: Prematurely born infants undergo costly, stressful eye examinations to uncover the small fraction with retinopathy of prematurity (ROP) that needs treatment to prevent blindness. The aim was to develop a prediction tool (DIGIROP-Screen) with 100% sensitivity and high specificity to safely reduce screening of those infants not needing treatment. DIGIROP-Screen was compared with four other ROP models based on longitudinal weights.METHODS: Data, including infants born at 24-30 weeks of gestational age (GA), for DIGIROP-Screen development (DevGroup, N=6991) originate from the Swedish National Registry for ROP. Three international cohorts comprised the external validation groups (ValGroups, N=1241). Multivariable logistic regressions, over postnatal ages (PNAs) 6-14 weeks, were validated. Predictors were birth characteristics, status and age at first diagnosed ROP and essential interactions.RESULTS: ROP treatment was required in 287 (4.1%)/6991 infants in DevGroup and 49 (3.9%)/1241 in ValGroups. To allow 100% sensitivity in DevGroup, specificity at birth was 53.1% and cumulatively 60.5% at PNA 8 weeks. Applying the same cut-offs in ValGroups, specificities were similar (46.3% and 53.5%). One infant with severe malformations in ValGroups was incorrectly classified as not needing screening. For all other infants, at PNA 6-14 weeks, sensitivity was 100%. In other published models, sensitivity ranged from 88.5% to 100% and specificity ranged from 9.6% to 45.2%.CONCLUSIONS: DIGIROP-Screen, a clinical decision support tool using readily available birth and ROP screening data for infants born GA 24-30 weeks, in the European and North American populations tested can safely identify infants not needing ROP screening. DIGIROP-Screen had equal or higher sensitivity and specificity compared with other models. DIGIROP-Screen should be tested in any new cohort for validation and if not validated it can be modified using the same statistical approaches applied to a specific clinical setting.
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| 9. |
- Pivodic, Aldina, 1978, et al.
(författare)
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Individual Risk Prediction for Sight-Threatening Retinopathy of Prematurity Using Birth Characteristics
- 2020
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Ingår i: JAMA Ophthalmology. - : American Medical Association (AMA). - 2168-6165 .- 2168-6173. ; 138:1, s. 21-29
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Tidskriftsartikel (refereegranskat)abstract
- Importance: To prevent blindness, repeated infant eye examinations are performed to detect severe retinopathy of prematurity (ROP), yet only a small fraction of those screened need treatment. Early individual risk stratification would improve screening timing and efficiency and potentially reduce the risk of blindness. Objectives: To create and validate an easy-to-use prediction model using only birth characteristics and to describe a continuous hazard function for ROP treatment. Design, Setting, and Participants: In this retrospective cohort study, Swedish National Patient Registry data from infants screened for ROP (born between January 1, 2007, and August 7, 2018) were analyzed with Poisson regression for time-varying data (postnatal age, gestational age [GA], sex, birth weight, and important interactions) to develop an individualized predictive model for ROP treatment (called DIGIROP-Birth [Digital ROP]). The model was validated internally and externally (in US and European cohorts) and compared with 4 published prediction models. Main Outcomes and Measures: The study outcome was ROP treatment. The measures were estimated momentary and cumulative risks, hazard ratios with 95% CIs, area under the receiver operating characteristic curve (hereinafter referred to as AUC), sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). Results: Among 7609 infants (54.6% boys; mean [SD] GA, 28.1 [2.1] weeks; mean [SD] birth weight, 1119 [353] g), 442 (5.8%) were treated for ROP, including 142 (40.1%) treated of 354 born at less than 24 gestational weeks. Irrespective of GA, the risk for receiving ROP treatment increased during postnatal weeks 8 through 12 and decreased thereafter. Validations of DIGIROP-Birth for 24 to 30 weeks' GA showed high predictive ability for the model overall (AUC, 0.90 [95% CI, 0.89-0.92] for internal validation, 0.94 [95% CI, 0.90-0.98] for temporal validation, 0.87 [95% CI, 0.84-0.89] for US external validation, and 0.90 [95% CI, 0.85-0.95] for European external validation) by calendar periods and by race/ethnicity. The sensitivity, specificity, PPV, and NPV were numerically at least as high as those obtained from CHOP-ROP (Children's Hospital of Philadelphia-ROP), OMA-ROP (Omaha-ROP), WINROP (weight, insulinlike growth factor 1, neonatal, ROP), and CO-ROP (Colorado-ROP), models requiring more complex postnatal data. Conclusions and Relevance: This study validated an individualized prediction model for infants born at 24 to 30 weeks' GA, enabling early risk prediction of ROP treatment based on birth characteristics data. Postnatal age rather than postmenstrual age was a better predictive variable for the temporal risk of ROP treatment. The model is an accessible online application that appears to be generalizable and to have at least as good test statistics as other models requiring longitudinal neonatal data not always readily available to ophthalmologists.
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| 10. |
- Pivodic, Aldina, 1978, et al.
(författare)
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Validation of the Retinopathy of Prematurity Activity Scale (ROP-ActS) using retrospective clinical data
- 2021
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Ingår i: Acta Ophthalmologica. - : Wiley. - 1755-375X .- 1755-3768. ; 99:2, s. 201-206
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Tidskriftsartikel (refereegranskat)abstract
- Purpose The International Neonatal Consortium recently published a proposed retinopathy of prematurity (ROP) activity scale intended for use in clinical trials after validation. The aim of this study was to validate the ROP activity scale (ROP-ActS) in a ROP screened cohort with protocol based collected data by evaluating the ability of the ROP-Act scores to predict ROP treatment. In addition, we aimed to evaluate the scale's sensitivity characteristic of disease severity by studying association with gestational age (GA) in comparison with conventionally used ROP stage and zone. Methods A cohort of 535 preterm infants with 3324 ROP examinations with an end-point of ROP treatment or end of screening in Gothenburg, Sweden, was included. Median GA was 28.1 weeks, 47.5% were girls, and 74 (13.8%) infants were treated for ROP. The validation was performed by estimating probabilities for ROP treatment, and by applying logistic and linear regression. Results The original ROP-ActS was overall well-ordered with respect to ability to predict ROP treatment but could be improved by re-ordering score 3 (zone II stage 1) and 5 (zone III stage 3) based on our clinical cohort data. The modified ROP-ActS was superior to ROP stage and zone in the prediction analysis of ROP treatment. Modified ROP-ActS was more strongly related to GA than currently used ROP stage, but not zone. Conclusion In the studied cohort, the modified ROP-ActS could better predict ROP treatment compared to ROP stage and zone. Retinopathy of Prematurity Activity Scale (ROP-ActS) had a superior sensitivity characteristic studied through association to GA than conventionally used ROP stage.
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