125 research outputs found
Lowest order stabilization free Virtual Element Method for the Poisson equation
We introduce and analyse the first order Enlarged Enhancement Virtual Element Method (E^2VEM) for the Poisson problem. The method has the interesting property of allowing the definition of bilinear forms that do not require a stabilization term. We provide a proof of well-posedness and optimal order a priori error estimates. Numerical tests on convex and non-convex polygonal meshes confirm the theoretical convergence rates
Lowest order stabilization free Virtual Element Method for the Poisson equation
We introduce and analyse the first order Enlarged Enhancement Virtual Element
Method (EVEM) for the Poisson problem. The method has the interesting
property of allowing the definition of bilinear forms that do not require a
stabilization term. We provide a proof of well-posedness and optimal order a
priori error estimates. Numerical tests on convex and non-convex polygonal
meshes confirm the theoretical convergence rates.Comment: 29 pages, 6 figure
Multi-BVOC Super-Resolution Exploiting Compounds Inter-Connection
Biogenic Volatile Organic Compounds (BVOCs) emitted from the terrestrial
ecosystem into the Earth's atmosphere are an important component of atmospheric
chemistry. Due to the scarcity of measurement, a reliable enhancement of BVOCs
emission maps can aid in providing denser data for atmospheric chemical,
climate, and air quality models. In this work, we propose a strategy to
super-resolve coarse BVOC emission maps by simultaneously exploiting the
contributions of different compounds. To this purpose, we first accurately
investigate the spatial inter-connections between several BVOC species. Then,
we exploit the found similarities to build a Multi-Image Super-Resolution
(MISR) system, in which a number of emission maps associated with diverse
compounds are aggregated to boost Super-Resolution (SR) performance. We compare
different configurations regarding the species and the number of joined BVOCs.
Our experimental results show that incorporating BVOCs' relationship into the
process can substantially improve the accuracy of the super-resolved maps.
Interestingly, the best results are achieved when we aggregate the emission
maps of strongly uncorrelated compounds. This peculiarity seems to confirm what
was already guessed for other data-domains, i.e., joined uncorrelated
information are more helpful than correlated ones to boost MISR performance.
Nonetheless, the proposed work represents the first attempt in SR of BVOC
emissions through the fusion of multiple different compounds.Comment: 5 pages, 4 figures, 1 table, accepted at EURASIP-EUSIPCO 202
Super-Resolution of BVOC Emission Maps Via Domain Adaptation
Enhancing the resolution of Biogenic Volatile Organic Compound (BVOC)
emission maps is a critical task in remote sensing. Recently, some
Super-Resolution (SR) methods based on Deep Learning (DL) have been proposed,
leveraging data from numerical simulations for their training process. However,
when dealing with data derived from satellite observations, the reconstruction
is particularly challenging due to the scarcity of measurements to train SR
algorithms with. In our work, we aim at super-resolving low resolution emission
maps derived from satellite observations by leveraging the information of
emission maps obtained through numerical simulations. To do this, we combine a
SR method based on DL with Domain Adaptation (DA) techniques, harmonizing the
different aggregation strategies and spatial information used in simulated and
observed domains to ensure compatibility. We investigate the effectiveness of
DA strategies at different stages by systematically varying the number of
simulated and observed emissions used, exploring the implications of data
scarcity on the adaptation strategies. To the best of our knowledge, there are
no prior investigations of DA in satellite-derived BVOC maps enhancement. Our
work represents a first step toward the development of robust strategies for
the reconstruction of observed BVOC emissions.Comment: 4 pages, 4 figures, 1 table, accepted at IEEE-IGARSS 202
Enhancing Biogenic Emission Maps Using Deep Learning
Biogenic Volatile Organic Compounds (BVOCs) play a critical role in
biosphere-atmosphere interactions, being a key factor in the physical and
chemical properties of the atmosphere and climate. Acquiring large and
fine-grained BVOC emission maps is expensive and time-consuming, so most of the
available BVOC data are obtained on a loose and sparse sampling grid or on
small regions. However, high-resolution BVOC data are desirable in many
applications, such as air quality, atmospheric chemistry, and climate
monitoring. In this work, we propose to investigate the possibility of
enhancing BVOC acquisitions, taking a step forward in explaining the
relationships between plants and these compounds. We do so by comparing the
performances of several state-of-the-art neural networks proposed for
Single-Image Super-Resolution (SISR), showing how to adapt them to correctly
handle emission data through preprocessing. Moreover, we also consider
realistic scenarios, considering both temporal and geographical constraints.
Finally, we present possible future developments in terms of Super-Resolution
(SR) generalization, considering the scale-invariance property and
super-resolving emissions from unseen compounds.Comment: 5 pages, 4 figures, 3 table
Mortality Related to Chronic Obstructive Pulmonary Disease during the COVID-19 Pandemic: An Analysis of Multiple Causes of Death through Different Epidemic Waves in Veneto, Italy
Mortality related to chronic obstructive pulmonary disease (COPD) during the COVID-19 pandemic is possibly underestimated by sparse available data. The study aimed to assess the impact of the pandemic on COPD-related mortality by means of time series analyses of causes of death data. We analyzed the death certificates of residents in Veneto (Italy) aged ≥40 years from 2008 to 2020. The age-standardized rates were computed for COPD as the underlying cause of death (UCOD) and as any mention in death certificates (multiple cause of death-MCOD). The annual percent change (APC) in the rates was estimated for the pre-pandemic period. Excess COPD-related mortality in 2020 was estimated by means of Seasonal Autoregressive Integrated Moving Average models. Overall, COPD was mentioned in 7.2% (43,780) of all deaths. From 2008 to 2019, the APC for COPD-related mortality was -4.9% (95% CI -5.5%, -4.2%) in men and -3.1% in women (95% CI -3.8%, -2.5%). In 2020 compared to the 2018-2019 average, the number of deaths from COPD (UCOD) declined by 8%, while COPD-related deaths (MCOD) increased by 14% (95% CI 10-18%), with peaks corresponding to the COVID-19 epidemic waves. Time series analyses confirmed that in 2020, COPD-related mortality increased by 16%. Patients with COPD experienced significant excess mortality during the first year of the pandemic. The decline in COPD mortality as the UCOD is explained by COVID-19 acting as a competing cause, highlighting how an MCOD approach is needed
Gerstmann-Sträussler-Scheinker disease subtypes efficiently transmit in bank voles as genuine prion diseases.
Gerstmann-Sträussler-Scheinker disease (GSS) is an inherited neurodegenerative disorder associated with mutations in the prion protein gene and accumulation of misfolded PrP with protease-resistant fragments (PrPres) of 6–8 kDa
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