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- Romanelli, F, et al.
(författare)
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Overview of the JET results
- 2011
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 51:9
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Tidskriftsartikel (refereegranskat)abstract
- Since the last IAEA Conference JET has been in operation for one year with a programmatic focus on the qualification of ITER operating scenarios, the consolidation of ITER design choices and preparation for plasma operation with the ITER-like wall presently being installed in JET. Good progress has been achieved, including stationary ELMy H-mode operation at 4.5 MA. The high confinement hybrid scenario has been extended to high triangularity, lower ρ*and to pulse lengths comparable to the resistive time. The steady-state scenario has also been extended to lower ρ*and ν*and optimized to simultaneously achieve, under stationary conditions, ITER-like values of all other relevant normalized parameters. A dedicated helium campaign has allowed key aspects of plasma control and H-mode operation for the ITER non-activated phase to be evaluated. Effective sawtooth control by fast ions has been demonstrated with3He minority ICRH, a scenario with negligible minority current drive. Edge localized mode (ELM) control studies using external n = 1 and n = 2 perturbation fields have found a resonance effect in ELM frequency for specific q95values. Complete ELM suppression has, however, not been observed, even with an edge Chirikov parameter larger than 1. Pellet ELM pacing has been demonstrated and the minimum pellet size needed to trigger an ELM has been estimated. For both natural and mitigated ELMs a broadening of the divertor ELM-wetted area with increasing ELM size has been found. In disruption studies with massive gas injection up to 50% of the thermal energy could be radiated before, and 20% during, the thermal quench. Halo currents could be reduced by 60% and, using argon/deuterium and neon/deuterium gas mixtures, runaway electron generation could be avoided. Most objectives of the ITER-like ICRH antenna have been demonstrated; matching with closely packed straps, ELM resilience, scattering matrix arc detection and operation at high power density (6.2 MW m-2) and antenna strap voltages (42 kV). Coupling measurements are in very good agreement with TOPICA modelling. © 2011 IAEA, Vienna.
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- Abel, I, et al.
(författare)
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Overview of the JET results with the ITER-like wall
- 2013
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 53:10, s. 104002-
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Tidskriftsartikel (refereegranskat)abstract
- Following the completion in May 2011 of the shutdown for the installation of the beryllium wall and the tungsten divertor, the first set of JET campaigns have addressed the investigation of the retention properties and the development of operational scenarios with the new plasma-facing materials. The large reduction in the carbon content (more than a factor ten) led to a much lower Z(eff) (1.2-1.4) during L- and H-mode plasmas, and radiation during the burn-through phase of the plasma initiation with the consequence that breakdown failures are almost absent. Gas balance experiments have shown that the fuel retention rate with the new wall is substantially reduced with respect to the C wall. The re-establishment of the baseline H-mode and hybrid scenarios compatible with the new wall has required an optimization of the control of metallic impurity sources and heat loads. Stable type-I ELMy H-mode regimes with H-98,H-y2 close to 1 and beta(N) similar to 1.6 have been achieved using gas injection. ELM frequency is a key factor for the control of the metallic impurity accumulation. Pedestal temperatures tend to be lower with the new wall, leading to reduced confinement, but nitrogen seeding restores high pedestal temperatures and confinement. Compared with the carbon wall, major disruptions with the new wall show a lower radiated power and a slower current quench. The higher heat loads on Be wall plasma-facing components due to lower radiation made the routine use of massive gas injection for disruption mitigation essential.
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- Stroth, U., et al.
(författare)
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Progress from ASDEX Upgrade experiments in preparing the physics basis of ITER operation and DEMO scenario development
- 2022
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 62:4
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Tidskriftsartikel (refereegranskat)abstract
- An overview of recent results obtained at the tokamak ASDEX Upgrade (AUG) is given. A work flow for predictive profile modelling of AUG discharges was established which is able to reproduce experimental H-mode plasma profiles based on engineering parameters only. In the plasma center, theoretical predictions on plasma current redistribution by a dynamo effect were confirmed experimentally. For core transport, the stabilizing effect of fast ion distributions on turbulent transport is shown to be important to explain the core isotope effect and improves the description of hollow low-Z impurity profiles. The L-H power threshold of hydrogen plasmas is not affected by small helium admixtures and it increases continuously from the deuterium to the hydrogen level when the hydrogen concentration is raised from 0 to 100%. One focus of recent campaigns was the search for a fusion relevant integrated plasma scenario without large edge localised modes (ELMs). Results from six different ELM-free confinement regimes are compared with respect to reactor relevance: ELM suppression by magnetic perturbation coils could be attributed to toroidally asymmetric turbulent fluctuations in the vicinity of the separatrix. Stable improved confinement mode plasma phases with a detached inner divertor were obtained using a feedback control of the plasma β. The enhanced D α H-mode regime was extended to higher heating power by feedback controlled radiative cooling with argon. The quasi-coherent exhaust regime was developed into an integrated scenario at high heating power and energy confinement, with a detached divertor and without large ELMs. Small ELMs close to the separatrix lead to peeling-ballooning stability and quasi continuous power exhaust. Helium beam density fluctuation measurements confirm that transport close to the separatrix is important to achieve the different ELM-free regimes. Based on separatrix plasma parameters and interchange-drift-Alfvén turbulence, an analytic model was derived that reproduces the experimentally found important operational boundaries of the density limit and between L- and H-mode confinement. Feedback control for the X-point radiator (XPR) position was established as an important element for divertor detachment control. Stable and detached ELM-free phases with H-mode confinement quality were obtained when the XPR was moved 10 cm above the X-point. Investigations of the plasma in the future flexible snow-flake divertor of AUG by means of first SOLPS-ITER simulations with drifts activated predict beneficial detachment properties and the activation of an additional strike point by the drifts.
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- Hellesen, Carl, 1980-, et al.
(författare)
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Neutron emission generated by fast deuterons accelerated with ion cyclotron heating at JET
- 2010
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 0029-5515 .- 1741-4326. ; 50:2
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Tidskriftsartikel (refereegranskat)abstract
- For the first time, the neutron emission from JET plasmas heated with combined deuterium neutral beam injection and third harmonic ion cyclotron radio frequency heating have been studied with neutron emission spectroscopy (NES). Very high DD neutron rates were observed with only modest external heating powers, which was attributed to acceleration of deuterium beam ions to energies of about 2-3 MeV, where the DD reactivity is on a par of that of the DT reaction. Fast deuterium energy distributions were derived from analysis of NES data and confirm acceleration of deuterium beam ions up to energies around 3 MeV, in agreement with theoretical predictions. The high neutron rates allowed for observations of changes in the fast deuterium populations on a time scale of 50 ms. Correlations were seen between fast deuterium ions at different energies and magnetohydrodynamic activities, such as monster sawtooth crashes and toroidal Alfven eigenmodes.
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23. |
- Hellesen, Carl, et al.
(författare)
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Validation of TRANSP Simulations Using Neutron emission Spectroscopy with Dual Sight Lines
- 2008
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Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 0034-6748 .- 1089-7623. ; 79:10, s. 10E510-
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Tidskriftsartikel (refereegranskat)abstract
- A method to generate modeled neutron spectra from bulk and fast ion distributions simulated by TRANSP has been developed. In this paper, modeled data generated from fuel ion distrubutions modeled with TRANSP is compared to measured data from two neutron spectrometers with different lines of sight; TOFOR with a radial one and the MPRu with a tangential one. The information obtained from the analysis of the measured neutron spectra such as the relative intensity of the emission from different ion populations places additional constraints on the simulation and can be used to adjust the parameters of the simulation.
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24. |
- Kuligowski, E., et al.
(författare)
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Evacuation modelling for bushfire : the WUI-NITY simulation platform
- 2022
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Ingår i: Australian Journal of Emergency Management. - 1324-1540. ; 37:4, s. 40-43
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Tidskriftsartikel (refereegranskat)abstract
- The number of people who live in bushfire-prone areas around the world is growing. In Australia, in the states of Victoria and New South Wales, over 1.5 million people live in areas rated as high to extreme bushfire risk in (SGS Economics and Planning 2019). As effects of climate change increase the size and severity of bushfires, and a greater number of people move into these at-risk areas, there is a growing imperative to understand the likely evacuation outcomes of bushfireprone communities under various fire scenarios. This paper introduces a freely available simulation platform called WUI-NITY that can be used by evacuation planners and decisionmakers to forecast evacuation behaviour within affected areas, and in turn, better prepare for and respond to future bushfire events.
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25. |
- Percetti, M., et al.
(författare)
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TWNK in Parkinson's Disease: A Movement Disorder and Mitochondrial Disease Center Perspective Study
- 2022
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Ingår i: Movement Disorders. - : Wiley. - 0885-3185 .- 1531-8257. ; 37:9, s. 1938-1943
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Tidskriftsartikel (refereegranskat)abstract
- Background Parkinsonian features have been described in patients harboring variants in nuclear genes encoding for proteins involved in mitochondrial DNA maintenance, such as TWNK. Objectives The aim was to screen for TWNK variants in an Italian cohort of Parkinson's disease (PD) patients and to assess the occurrence of parkinsonism in patients presenting with TWNK-related autosomal dominant progressive external ophthalmoplegia (TWNK-adPEO). Methods Genomic DNA of 263 consecutively collected PD patients who underwent diagnostic genetic testing was analyzed with a targeted custom gene panel including TWNK, as well as genes causative of monogenic PD. Genetic and clinical data of 18 TWNK-adPEO patients with parkinsonism were retrospectively analyzed. Results Six of 263 PD patients (2%), presenting either with isolated PD (n = 4) or in combination with bilateral ptosis (n = 2), carried TWNK likely pathogenic variants. Among 18 TWNK-adPEO patients, 5 (28%) had parkinsonism. Conclusions We show candidate TWNK variants occurring in PD without PEO. This finding will require further confirmatory studies. (c) 2022 Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson Movement Disorder Society.
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26. |
- Ronchi, E, et al.
(författare)
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A Neural Networks Framework for Real-Time Unfolding of Neutron Spectroscopic Data at JET
- 2008
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Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 0034-6748 .- 1089-7623. ; 79:10, s. 10E513-
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Tidskriftsartikel (refereegranskat)abstract
- A determination of fast ion population parameters such as intensity and kinetic temperature is important for fusion reactors. This becomes more challenging with finer time resolution of the measurements, since the limited data in each time slice cause increasing statistical variations in the data. This paper describes a framework using Bayesian-regularized neural networks (NNs) designed for such a task. The method is applied to the TOFOR 2.5 MeV fusion neutron spectrometer at JET. NN training data are generated by random sampling of variables in neutron spectroscopy models. Ranges and probability distributions of the parameters are chosen to match the experimental data. Results have shown good performance both on synthetic and experimental data. The latter was assessed by statistical considerations and by examining the robustness and time consistency of the results. The regularization of the training algorithm allowed for higher time resolutions than simple forward methods. The fast execution time makes this approach suitable for real-time analysis with a time resolution limit in the microsecond time scale.
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- Ronchi, E., et al.
(författare)
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The verification of wildland–urban interface fire evacuation models
- 2023
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Ingår i: Natural Hazards. - : Springer Science and Business Media LLC. - 0921-030X .- 1573-0840. ; 117:2, s. 1493-1519
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Tidskriftsartikel (refereegranskat)abstract
- This paper introduces a protocol for the verification of multi-physics wildfire evacuation models, including a set of tests used to ensure that the conceptual modelling representation of each modelling layer is accurately implemented, as well as the interactions between different modelling layers and sub-models (wildfire spread, pedestrian movement, traffic evacuation, and trigger buffers). This work presents a total of 24 verification tests, including (1) 4 tests related to pedestrians, (2) 15 tests for traffic evacuation, (3) 5 tests concerning the interaction between different modelling layers, along with 5 tests for wildfire spread and trigger buffers. The evacuation tests are organized in accordance with different core components related to evacuation modelling, namely Population, Pre-evacuation, Movement, Route/destination selection, Flow constraints, Events, Wildfire spread and Trigger buffers. A reporting template has also been developed to facilitate the application of the verification testing protocol. An example application of the testing protocol has been performed using an open wildfire evacuation modelling platform called WUI-NITY and its associated trigger buffer model k-PERIL. The verification testing protocol is deemed to improve the credibility of wildfire evacuation model results and stimulate future modelling efforts in this domain.
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- Andersson Sundén, Erik, et al.
(författare)
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The thin-foil magnetic proton recoil neutron spectrometer MPRu at JET
- 2009
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 610:3, s. 682-699
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Tidskriftsartikel (refereegranskat)abstract
- Neutrons are produced in fusion energy experiments with both deuterium (D) and deuterium–tritium (DT) plasmas. Neutron spectroscopy is a valuable tool in the study of the underlying fuel ion populations. The magnetic proton recoil neutron spectrometer, originally installed at JET in 1996 for 14-MeV neutron measurements, has been upgraded, with the main aim of improving its signal-to-background ratio (S/B), making measurements of the 2.5-MeV neutron emission in D plasmas possible. The upgrade includes a new focal-plane detector, based on the phoswich technique and consequently less sensitive to background, and a new custom-designed digital data acquisition system based on transient recorder cards. Results from JET show that the upgraded MPRu can measure 2.5-MeV neutrons with S/B=5, an improvement by a factor of 50 compared with the original MPR. S/B of 2.8×104 in future DT experiments is estimated. The performance of the MPRu is exemplified with results from recent D plasma operations at JET, concerning both measurements with Ohmic, ion cyclotron resonance (ICRH) and neutral beam injection (NBI) plasma heating, as well as measurements of tritium burn-up neutrons. The upgraded instrument allows for 2.5-MeV neutron emission and deuterium ion temperature measurements in plasmas with low levels of tritium, a feature necessary for the ITER experiment.
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- Carlsson, G., et al.
(författare)
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A scoping review of public building accessibility
- 2022
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Ingår i: Disability and Health Journal. - : Elsevier BV. - 1936-6574. ; 15:2
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Forskningsöversikt (refereegranskat)abstract
- Background: The built environment needs to be designed so that all people can participate in the activities they want and need to do. Yet, accessibility is difficult to put into practice, and accessibility issues tend to be overlooked in the building and planning processes. Objectives: The aim of this scoping review was to summarize the research front in the area of accessibility to public buildings. Specific aims were to identify knowledge gaps, to identify access activities in relation to environmental features and to link to predominant activities in terms of the International Classification of Functioning, Disability and Health (ICF). Methods: A literature search was performed in PubMed, PsycINFO, Inspec, Embase and Cochrane databases. Articles in English based on original empirical studies investigating accessibility of public buildings for adults aged ≥18 years with functional limitations were considered. Results: Of the 40 articles included, ten involved study participants, while 30 only examined buildings using instruments to assess accessibility. In addition, the psychometric properties were only tested for a few of them. All articles concerned mobility and several visual limitations, while few addressed cognitive or hearing limitations. Ten main access activities were identified, from using parking/drop-off area to exiting building. Conclusions: By using the ICF and theoretically relating the accessibility problems to activities, the results revealed that there are large knowledge gaps about accessibility to public buildings for older people and people with functional limitations and that there is a need for more methodological considerations in this area of research.
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35. |
- De Ronchi, D, et al.
(författare)
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Occurrence of cognitive impairment and dementia after the age of 60: a population-based study from Northern Italy
- 2005
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Ingår i: Dementia and geriatric cognitive disorders. - : S. Karger AG. - 1420-8008 .- 1421-9824. ; 19:2-3, s. 97-105
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Tidskriftsartikel (refereegranskat)abstract
- <i>Objective:</i> To evaluate the age, gender and education distribution of both cognitive impairment and dementia in the whole old age range of the elderly (from 61 years of age and over). <i>Subjects and Methods:</i> The study population consisted of all subjects born in 1930 or before, living in the municipality of Faenza and Granarolo, Italy (n = 7,930). A two-phase study design was implemented, by using the Mini-Mental State Examination and Global Deterioration Scale as screening instruments. The DSM-III-R diagnostic criteria were used for the clinical diagnosis of dementia. A subject was classified as affected by cognitive impairment, no dementia (CIND) if he/she scored 2 or more standard deviations lower than the corrected mean MMSE score. <i>Results:</i> The prevalences of dementia and CIND were 6.5 per 100 (95% CI 5.9–7.0) and 5.1 per 100 (95% CI 4.6–5.6), respectively. The prevalence of CIND was higher than that of dementia in the youngest old groups (61–74 years), both in men and women, whereas the opposite pattern was present among the older old (75+). In the older age groups, dementia prevalence increased exponentially with age, while CIND prevalence was more stable. There was not a substantial gender difference in CIND prevalence in all ages. Only in the subpopulation of higher educated subjects, women had a higher prevalence of both dementia and CIND than men. Lower educated subjects had a higher prevalence of both dementia and CIND. When compared to higher educated persons, subjects without any schooling had odds ratios of 10.9 (CI 7.0–16.7) and 16.7 (CI 11.2–25.0) for dementia and CIND, respectively. <i>Conclusions:</i> Cognitive impairment is very common in the younger old ages (under 70 years of age), whereas dementia becomes predominant after 75 years of age. Both conditions are strongly related to the educational level.
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- De Ronchi, D, et al.
(författare)
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The combined effect of age, education, and stroke on dementia and cognitive impairment no dementia in the elderly
- 2007
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Ingår i: Dementia and geriatric cognitive disorders. - : S. Karger AG. - 1420-8008 .- 1421-9824. ; 24:4, s. 266-273
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Tidskriftsartikel (refereegranskat)abstract
- <i>Background:</i> This study aims to detect the impact of stroke on the occurrence of dementia and cognitive impairment/no dementia (CIND) in different age, sex, and education groups. <i>Methods:</i> Persons with dementia (DSM-III-R) or CIND were identified by a two-phase study design among 7,930 persons from the population-based Faenza Community Aging Study. <i>Results:</i> Subjects with a history of stroke had increased risk of both dementia [risk ratio (RR) = 3.7; 95% confidence interval (CI) = 3.1–4.4] and CIND (RR = 1.7, 95% CI = 1.4–2.2). These associations were stronger in the younger-old (61–74 years) than in the older-old (75+ years), and among higher-educated (4+ years) than lower-educated (0–3 years of schooling) persons. Dementia and CIND prevalence among stroke subjects was similar to the prevalence detected among subjects 10 years older but without a history of stroke. In stroke subjects, dementia prevalence became higher than CIND prevalence 10 years earlier than in non-stroke subjects. A combined effect for dementia due to a history of stroke, increasing age, and decreasing years of schooling was detected. <i>Conclusions:</i> Stroke is a strong risk factor for dementia among younger-old and higher-educated subjects; in the presence of a stroke, dementia onset might occur about 10 years earlier, possibly by accelerating the progression from CIND to dementia.
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- Lovreglio, R, et al.
(författare)
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The need of latent variables for modelling decision-making in evacuation simulations
- 2015
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Ingår i: IX International Workshop on Planning and Evaluation.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Evacuation models generally tend to make over-simplifications in the representation of human behaviour in fire due to the difficulties to capture its complexity. This work shows how ‘new’ discrete choice model approaches allow overcoming this issue. A description of the existing state-of-the-art of discrete choice models is introduced to highlight the potential of those models. Three case studies are introduced describing an application of the Random Utility Theory to simulate evacuees’ decisions pertaining to the strategic, tactical and operational levels. This work highlights the need for new datasets including indicators which allows estimating latent factors which may affect evacuees’ decision.
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- Prusakov, Pavel, et al.
(författare)
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A global point prevalence survey of antimicrobial use in neonatal intensive care units : The no-more-antibiotics and resistance (NO-MAS-R) study
- 2021
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Ingår i: eClinicalMedicine. - : Elsevier. - 2589-5370. ; 32
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Tidskriftsartikel (refereegranskat)abstract
- Background: Global assessment of antimicrobial agents prescribed to infants in the neonatal intensive care unit (NICU) may inform antimicrobial stewardship efforts.Methods: We conducted a one-day global point prevalence study of all antimicrobials provided to NICU infants. Demographic, clinical, and microbiologic data were obtained including NICU level, census, birth weight, gestational/chronologic age, diagnoses, antimicrobial therapy (reason for use; length of therapy), antimicrobial stewardship program (ASP), and 30-day in-hospital mortality.Findings: On July 1, 2019, 26% of infants (580/2,265; range, 0-100%; median gestational age, 33 weeks; median birth weight, 1800 g) in 84 NICUs (51, high-income; 33, low-to-middle income) from 29 countries (14, high-income; 15, low-to-middle income) in five continents received >= 1 antimicrobial agent (92%, antibacterial; 19%, antifungal; 4%, antiviral). The most common reasons for antibiotic therapy were "rule-out" sepsis (32%) and "culture-negative" sepsis (16%) with ampicillin (40%), gentamicin (35%), amikacin (19%), vancomycin (15%), and meropenem (9%) used most frequently. For definitive treatment of presumed/confirmed infection, vancomycin (26%), amikacin (20%), and meropenem (16%) were the most prescribed agents. Length of therapy for culture-positive and "culture-negative" infections was 12 days (median; IQR, 8-14) and 7 days (median; IQR, 5-10), respectively. Mortality was 6% (42%, infection-related). An NICU ASP was associated with lower rate of antibiotic utilization (p = 0.02).Interpretation: Global NICU antibiotic use was frequent and prolonged regardless of culture results. NICU-specific ASPs were associated with lower antibiotic utilization rates, suggesting the need for their implementation worldwide.
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42. |
- Ronchi, Emanuele, 1978-, et al.
(författare)
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A neural network pulse shape discrimination and pile-up rejection framework for the BC501 neutron/gamma liquid scintillator
- 2009
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 610:2, s. 534-539
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Tidskriftsartikel (refereegranskat)abstract
- BC-501 is a liquid scintillation detector sensitive to both neutrons and gamma rays. As these produce slightly different signals in the detector, they can be discriminated based on their pulse shape (Pulse Shape Discrimination, PSD). This paper reports on results obtained with several PSD techniques and compares them with a method based on artificial neural networks (NN) developed for this application. Results indicated a large performance advantage of NN especially in the region of small deposited energy which typically contains the majority of the events. NN were also applied for discrimination of pile-up events with good results. This framework can be implemented on some of the most recent programmable data acquisition cards and it is suitable for real-time application.
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43. |
- Ronchi, E., et al.
(författare)
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Applications of neural networks for free unfolding of experimental data from fusion neutron spectrometers
- 2010
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Ingår i: International Journal of Nuclear Knowledge Management. ; 4:1, s. 25-31
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Tidskriftsartikel (refereegranskat)abstract
- Free unfolding in neutron spectroscopy means reconstructing energy spectra from experimental data without a priori assumptions regarding their shape. Due to the ill-conditioned nature of the problem, this cannot be done analytically. Neural Networks (NNs) were applied to this task and synthetic data was used for training and testing. Results showed very consistent performance especially in the region of low and medium counts, where they fall near the Poisson statistical boundary. Comparison with other unfolding methods validated these results. Application time on the order of mus makes NNs suitable for real-time analysis. This approach can be applied to any instrument of which the response function is known.
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