5,666 research outputs found
An Integrated Software Platform for Best Estimate Safety Analyses of Nuclear Power Plants
Nuclear power plant safety is granted through the demonstration that regulatory acceptance
criteria are fulfilled by the provided (calculated) analyses of the NPP performances and sufficient safety
margins are respected during normal operation, anticipated transients and postulated accident conditions.
Safety margins are very hard to determine in absolute terms, numerical calculations are used to assess
their values. Over the last 30 years an extensive effort has been carried out aiming to improve the
knowledge of the nuclear power plant behaviour under transient scenarios. The development of Best
Estimate (BE) computer codes are the direct consequence of these noteworthy efforts.
The availability of more sophisticated and specialized computer codes gives the analyst the possibility to
perform very detailed analysis in all the fields involved in the safety of a NPP: thermal-hydraulics, CFD,
3D neutron kinetics etc. The possibility to create a software environment where a multidisciplinary
problem can be solved adopting different specialized codes able to exchange data among them is a fruitful
approach to the problem aiming to improve the results.
The computational tools, adopted in best-estimate approach in licensing, include a) the best estimate
computer codes; b) the nodalizations together with the procedures for the development and the
qualification; c) the uncertainty methodology.
The Nuclear Research Group of San Piero a Grado of the University of Pisa has developed a software
platform with 15 interacting computer codes. Such platform covers the reactor simulation multidisciplinary
problem from generation of neutron cross-sections, through system thermal-hydraulic analyses, up to
detailed structural and fuel mechanics studies and it embeds software procedures for automatized data
transfer between codes. Together with methodological procedures for nodalizations development and
qualification the platform leads to a great decrease of the human induced error in the results. The
developed platform has been tested and successfully applied to perform the safety analyses required by the
Chapter 15 of the Final Safety Analysis Report of the CNA-2 nuclear power plant in Argentina
Transcranial cortico-cortical paired associative stimulation (ccPAS) over ventral premotor-motor pathways enhances action performance and corticomotor excitability in young adults more than in elderly adults
Transcranial magnetic stimulation (TMS) methods such as cortico-cortical paired associative stimulation (ccPAS) can increase the strength of functional connectivity between ventral premotor cortex (PMv) and primary motor cortex (M1) via spike timing-dependent plasticity (STDP), leading to enhanced motor functions in young adults. However, whether this STDP-inducing protocol is effective in the aging brain remains unclear. In two groups of young and elderly healthy adults, we evaluated manual dexterity with the 9-hole peg task before and after ccPAS of the left PMv-M1 circuit. We observed that ccPAS enhanced dexterity in young adults, and this effect was anticipated by a progressive increase in motor-evoked potentials (MEPs) during ccPAS administration. No similar effects were observed in elderly individuals or in a control task. Across age groups, we observed that the magnitude of MEP changes predicted larger behavioral improvements. These findings demonstrate that left PMv-to-M1 ccPAS induces functionally specific improvements in young adults' manual dexterity and an increase in corticomotor excitability, but altered plasticity prevents the effectiveness of ccPAS in the elderly
Whale-watching contributions for the study of cetacean-cephalopod interactions
Cephalopods are the primary source of food for several species of odontocetes. The unstable nature of this trophic resource is likely to affect the ecology of their cetacean predators. This can be reflected in whale conservation status but also in the tourist activities which focus on cetacean observation. However, the study of cetacean-cephalopod interactions is limited by the complicated and heavy logistics of dedicated scientific campaigns. Fortunately, this limitation can be overcome by coupling modern molecular tools with indirect sampling methods. In this note we present the first results of a project to involve whale watching companies, which represent an intense observation effort worldwide, in the collection of biological material and information for studies of cetacean-cephalopod interactions and cephalopod distribution. In early 2020 we contacted all whale watching companies on São Miguel Island, Azores. All of them welcomed the invitation and received training and a sampling kit. Nine cephalopod tissue samples were collected, most of them in close association with sperm whales. All samples were determined by DNA barcoding (confirmed in a few cases by morphological observation) to belong to the gelatinous giant octopod Haliphron atlanticus (Octopoda, Alloposidae). We believe that, although the Azores may have particularly favourable conditions for participatory science, similar programs can be replicated elsewhere.info:eu-repo/semantics/publishedVersio
Neurophysiological Markers of Premotor–Motor Network Plasticity Predict Motor Performance in Young and Older Adults
Aging is commonly associated with a decline in motor control and neural plasticity. Tuning cortico–cortical interactions between premotor and motor areas is essential for controlling fine manual movements. However, whether plasticity in premotor–motor circuits predicts hand motor abilities in young and elderly humans remains unclear. Here, we administered transcranial magnetic stimulation (TMS) over the ventral premotor cortex (PMv) and primary motor cortex (M1) using the cortico–cortical paired-associative stimulation (ccPAS) protocol to manipulate the strength of PMv-to-M1 connectivity in 14 young and 14 elderly healthy adults. We assessed changes in motor-evoked potentials (MEPs) during ccPAS as an index of PMv-M1 network plasticity. We tested whether the magnitude of MEP changes might predict interindividual differences in performance in two motor tasks that rely on premotor-motor circuits, i.e., the nine-hole pegboard test and a choice reaction task. Results show lower motor performance and decreased PMv-M1 network plasticity in elderly adults. Critically, the slope of MEP changes during ccPAS accurately predicted performance at the two tasks across age groups, with larger slopes (i.e., MEP increase) predicting better motor performance at baseline in both young and elderly participants. These findings suggest that physiological indices of PMv-M1 plasticity could provide a neurophysiological marker of fine motor control across age-groups
Analysis and hindcast simulations of an extreme rainfall event in the Mediterranean area: The Genoa 2011 case
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Factorial Economic Planning Applied to Agricultural Experimentation
Innovation may be limited by the scarceness of resources, such as financial, homogeneous area, skilled labor or other research needs, for example the difficulty in experimental control of large areas in the field. In research areas such as chemistry and physics, designs are used in such a way that when compared to the agronomic designs, they result in a reduced number of experimental units, which in this work are called economic designs. Thus, the objective of this study was to identify significant factors and effects (p-valu
Mapeamento de áreas suscetÃveis a deslizamentos no municÃpio de Pato Branco, Paraná com a aplicação do modelo SHALSTAB
Este trabalho compara modelos matemáticos de estabilidade de encostas associados a técnicas de mapeamento temático em SIG. O objetivo principal foi avaliar a aplicação do modelo SHALSTAB no mapeamento de áreas suscetÃveis à ocorrência de escorregamentos na região de Pato Branco, Paraná, buscando determinar a quantidade de chuva necessária para desencadear estes eventos extremos e comparar com resultados de trabalhos anteriores que determinaram os fatores de segurança das encostas dessa área. Os resultados obtidos demonstraram que ambas metodologias analisadas mostraram-se aptas como ferramenta para identificar zonas de susceptibilidade à ocorrência de escorregamento raso, uma vez que os deslizamentos ocorridos na cidade estão localizados em áreas consideradas instáveis pelos dois métodos.This paper compares mathematical models of slope stability associated with thematic mapping techniques in GIS. The main objective was to evaluate the application of SHALSTAB model in the susceptible mapping areas to the occurrence of landslides in Pato Branco, Paraná State, aiming to determine the needed amount of rain to trigger these extreme events and to compare, with previous studies results, what have determined the security factors of the slopes in this area. The results showed that both analyzed methodologies proved suitable as a tool for identifying susceptibility to the occurrence of slip shallow areas, once the slips occurred in the city are located in areas considered unstable by both methods
Blastic plasmacytoid dendritic cell neoplasm : State of the art and prospects
Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is an extremely rare tumour, which usually a_ects elderly males and presents in the skin with frequent involvement of the bone-marrow, peripheral blood and lymph nodes. It has a dismal prognosis, with most patients dying within one year when treated by conventional chemotherapies. The diagnosis is challenging, since neoplastic cells can resemble lymphoblasts or small immunoblasts, and require the use of a large panel of antibodies, including those against CD4, CD56, CD123, CD303, TCL1, and TCF4. The morphologic and in part phenotypic ambiguity explains the uncertainties as to the histogenesis of the neoplasm that led to the use of various denominations. Recently, a series of molecular studies based on karyotyping, gene expression profiling, and next generation sequencing, have largely unveiled the pathobiology of the tumour and proposed the potentially beneficial use of new drugs. The latter include SL-401, anti-CD123 immunotherapies, venetoclax, BET-inhibitors, and demethylating agents. The epidemiologic, clinical, diagnostic, molecular, and therapeutic features of BPDCN are thoroughly revised in order to contribute to an up-to-date approach to this tumour that has remained an orphan disease for too long
Testing the performance of a blind burst statistic
In this work we estimate the performance of a method for the detection of
burst events in the data produced by interferometric gravitational wave
detectors. We compute the receiver operating characteristics in the specific
case of a simulated noise having the spectral density expected for Virgo, using
test signals taken from a library of possible waveforms emitted during the
collapse of the core of Type II Supernovae.Comment: 8 pages, 6 figures, Talk given at the GWDAW2002 worksho
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