1,371 research outputs found
A CNN-based fusion method for feature extraction from sentinel data
Sensitivity to weather conditions, and specially to clouds, is a severe limiting factor to the use of optical remote sensing for Earth monitoring applications. A possible alternative is to benefit from weather-insensitive synthetic aperture radar (SAR) images. In many real-world applications, critical decisions are made based on some informative optical or radar features related to items such as water, vegetation or soil. Under cloudy conditions, however, optical-based features are not available, and they are commonly reconstructed through linear interpolation between data available at temporally-close time instants. In this work, we propose to estimate missing optical features through data fusion and deep-learning. Several sources of information are taken into accountâoptical sequences, SAR sequences, digital elevation modelâso as to exploit both temporal and cross-sensor dependencies. Based on these data and a tiny cloud-free fraction of the target image, a compact convolutional neural network (CNN) is trained to perform the desired estimation. To validate the proposed approach, we focus on the estimation of the normalized difference vegetation index (NDVI), using coupled Sentinel-1 and Sentinel-2 time-series acquired over an agricultural region of Burkina Faso from MayâNovember 2016. Several fusion schemes are considered, causal and non-causal, single-sensor or joint-sensor, corresponding to different operating conditions. Experimental results are very promising, showing a significant gain over baseline methods according to all performance indicators
A twin-bed test reactor for characterization of calcium looping sorbents
The reduction of sorbent CO2 capture capacity and the extent of particle attrition over iterated cycles are relevant to design of Calcium Looping processes (1-2). Thermogravimetric analyzers or fluidized bed reactors are generally used to evaluate the sorbent performance. One drawback of these reactors is that they do not reproduce the thermal history that is actually experienced by sorbent particles in real looping cycles. In this study, a novel experimental technique is proposed to overcome this limitation. The apparatus consists of two interconnected fluidized bed reactors operating as calciner and carbonator, respectively (Fig. 1). The two reactors are connected each other by a duct (whose openings can be located at adjustable level above the gas distributor) which permits pneumatic transport of the solids between the reactors. Silica sand is used as buffering inert material to prevent excessive temperature fluctuations due to solid transport and chemical reactions. The operating conditions (fluidization velocity and duct height) of the reactor have been tuned to maximize transfer of the sorbent at each cycle, while limiting the transport of sand (Fig. 2). Further tests were carried out to simulate multiple calcination/carbonation cycles (Fig. 3). Under the optimal experimental conditions more than 95% collection efficiency of the limestone was obtained while less than half of the sand was transferred. Additional tests were carried out at high temperature but under non-reacting conditions, so as to simulate the real thermal history of the particles.
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nIFTy cosmology: comparison of galaxy formation models
We present a comparison of 14 galaxy formation models: 12 different semi-analytical models and 2 halo occupation distribution models for galaxy formation based upon the same cosmological simulation and merger tree information derived from it. The participating codes have proven to be very successful in their own right but they have all been calibrated independently using various observational data sets, stellar models, and merger trees. In this paper, we apply them without recalibration and this leads to a wide variety of predictions for the stellar mass function, specific star formation rates, stellar-to-halo mass ratios, and the abundance of orphan galaxies. The scatter is much larger than seen in previous comparison studies primarily because the codes have been used outside of their native environment within which they are well tested and calibrated. The purpose of the 'nIFTy comparison of galaxy formation models' is to bring together as many different galaxy formation modellers as possible and to investigate a common approach to model calibration. This paper provides a unified description for all participating models and presents the initial, uncalibrated comparison as a baseline for our future studies where we will develop a common calibration framework and address the extent to which that reduces the scatter in the model predictions seen here.La lista completa de autores que integran el documento puede consultarse en el archivo.Instituto de AstrofĂsica de La PlataFacultad de Ciencias AstronĂłmicas y GeofĂsica
nIFTy cosmology: comparison of galaxy formation models
We present a comparison of 14 galaxy formation models: 12 different semi-analytical models and 2 halo occupation distribution models for galaxy formation based upon the same cosmological simulation and merger tree information derived from it. The participating codes have proven to be very successful in their own right but they have all been calibrated independently using various observational data sets, stellar models, and merger trees. In this paper, we apply them without recalibration and this leads to a wide variety of predictions for the stellar mass function, specific star formation rates, stellar-to-halo mass ratios, and the abundance of orphan galaxies. The scatter is much larger than seen in previous comparison studies primarily because the codes have been used outside of their native environment within which they are well tested and calibrated. The purpose of the 'nIFTy comparison of galaxy formation models' is to bring together as many different galaxy formation modellers as possible and to investigate a common approach to model calibration. This paper provides a unified description for all participating models and presents the initial, uncalibrated comparison as a baseline for our future studies where we will develop a common calibration framework and address the extent to which that reduces the scatter in the model predictions seen here.La lista completa de autores que integran el documento puede consultarse en el archivo.Instituto de AstrofĂsica de La PlataFacultad de Ciencias AstronĂłmicas y GeofĂsica
Environmental and territorial modelling for planning and design
[English]: Between 5th and 8th September 2018 the tenth edition of the INPUT conference took place in Viterbo, guests of the beautiful setting of the University of Tuscia and its DAFNE Department.
INPUT is managed by an informal group of Italian academic researchers working in many fields related to the exploitation of informatics in planning.
This Tenth Edition pursed multiple objectives with a holistic, boundary-less character, to face the complexity of today socio-ecological systems following a systemic approach aimed to problem solving. In particular, the Conference will aim to present the state of art of modeling approaches employed in urban and territorial planning in national and international contexts.
Moreover, the conference has hosted a Geodesign workshop, by Carl Steinitz (Harvard Graduate School of Design) and Hrishi Ballal (on skype), Tess Canfield, Michele Campagna.
Finally, on the last day of the conference, took place the QGIS hackfest, in which over 20 free software developers from all over Italy discussed the latest news and updates from the QGIS network.
The acronym INPUT was born as INformatics for Urban and Regional Planning. In the transition to graphics, unintentionally, the first term was transformed into âInnovationâ, with a fine example of serendipity, in which a small mistake turns into something new and intriguing. The opportunity is taken to propose to the organizers and the scientific committee of the next appointment to formalize this change of the acronym.
This 10th edition was focused on Environmental and Territorial Modeling for planning and design. It has been considered a fundamental theme, especially in relation to the issue of environmental sustainability, which requires a rigorous and in-depth analysis of processes, a theme which can be satisfied by the territorial information systems and, above all, by modeling simulation of processes.
In this topic, models are useful with the managerial approach, to highlight the many aspects of complex city and landscape systems. In consequence, their use must be deeply critical, not for rigid forecasts, but as an aid to the management decisions of complex systems.[Italiano]:Dal 5 allâ8 settembre 2018 lâUniversitĂ della Tuscia e il Dipartimento di Scienze Agrarie e Forestali - DAFNE hanno ospitato la decima edizione del Congresso Internazionale INPUT.
INPUT Ăš un gruppo informale di ricercatori accademici italiani che operano in molti settori connessi allâuso dellâinformatica nella pianificazione.
Questa decima edizione del Congresso ha perseguito obiettivi multipli con un carattere olistico, senza confini, per affrontare la complessitĂ degli attuali sistemi socio-ecologici seguendo un approccio sistemico finalizzato alla risoluzione dei problemi. In particolare, la conferenza Ăš stata orientata a presentare lo stato dell'arte degli approcci di modellazione impiegati nella pianificazione urbana e territoriale in contesti nazionali e internazionali.
Inoltre, la conferenza ha ospitato un seminario di Geodesign, di Carl Steinitz (Harvard Graduate School of Design) e Hrishi Ballal (via skype), Tess Canfield e Michele Campagna.
Infine, l'ultimo giorno della conferenza, si Ăš svolto lâhackfest di QGIS, in cui oltre 20 sviluppatori di software open source provenienti da tutta Italia hanno discusso le ultime novitĂ e gli aggiornamenti dalla rete QGIS.
L'acronimo âINPUTâ Ăš nato come âINformatics per Urban and Regional Planningâ. Nella transizione alla grafica, involontariamente, il primo termine Ăš stato trasformato in "Innovazione", con un bell'esempio di serendipitĂ , in cui un piccolo errore si trasforma in qualcosa di nuovo e intrigante
Protein tyrosine phosphatase activity modulation by endothelin-1 in rabbit platelets
AbstractProtein tyrosine phosphorylation, modulated by the rate of both protein tyrosine kinase and protein tyrosine phosphatase activities, is critical for cellular signal transduction cascades. We report that endothelin-1 stimulation of rabbit platelets resulted in a dose- and time-dependent tyrosine phosphorylation of four groups of proteins in the molecular mass ranges of 50, 60, 70â100 and 100â200 kDa and that one of these corresponds to focal adhesion kinase. This effect is also related to the approximately 60% decrease in protein tyrosine phosphatase activity. Moreover, this inhibited activity was less sensitive to orthovanadate. In the presence of forskolin that increases the cAMP level a dose-dependent inhibition of the endothelin-stimulated tyrosine phosphorylation of different protein substrates and a correlation with an increase in the protein tyrosine phosphatase activity (11.6-fold compared to control) have been found. Further studies by immunoblotting of immunoprecipitated soluble fraction with anti-protein tyrosine phosphatase-1C from endothelin-stimulated platelets have demonstrated that the tyrosine phosphorylation of platelet protein tyrosine phosphatase-1C is correlated with the decrease in its phosphatase activity. As a consequence, modulation and regulation by endothelin-1 in rabbit platelets can be proposed through a cAMP-dependent pathway and a tyrosine phosphorylation process that may affect some relevant proteins such as focal adhesion kinase
Epipactis tremolsii seed diversity in two close but extremely different populations: Just a case of intraspecific variability?
Analysis of the seed morphology is a widely used approach in ecological and taxonomic studies. In this context, intraspecific variability with respect to seed morphology (size, weight, and density) was assessed in two close Epipactis tremolsii Pau. populations sharing the same ecological conditions, except for the soil pollution distinguishing one of them. Larger and heavier seeds were found in plants growing on the heavy metal polluted site, while no differences in seed density were detected between seeds produced by plants growing on the contaminated and the control site. Moreover, seed coats and embryos varying together in their dimensions were described in the control population, while coats varying in their size independently from embryos were described in plants growing on the polluted site. Seeds from the two studied populations significantly differed in several parameters suggesting that intraspecific seed variability occurred in the case study
On the power spectrum of motor unit action potential trains synchronized with mechanical vibration
Objective: Provide a definitive analysis of the spectrum of a motor unit action potential train elicited by mechanical vibratory stimulation via a detailed and concise mathematical formulation. Experimental studies demonstrated that motor unit action potentials are not exactly synchronized with the vibratory stimulus but show a variable latency jitter, whose effects have not been investigated yet. Methods: Synchronized action potential train was represented as a quasi-periodic sequence of a given motor unit waveform. The latency jitter of action potentials was modeled as a Gaussian stochastic process, in accordance to previous experimental studies. Results: A mathematical expression for power spectrum of a synchronized motor unit action potential train has been derived. The spectrum comprises a significant continuous component and discrete components at the vibratory frequency and its harmonics. Their relevance is correlated to the level of synchronization: the weaker the synchronization, the more relevant the continuous spectrum. EMG rectification enhances the discrete components. Conclusion: The derived equations have general validity and well describe the power spectrum of actual EMG recordings during vibratory stimulation. Results are obtained by appropriately setting the level of synchronization and vibration frequency. Significance: This study definitively clarifies the nature of changes in spectrum of raw EMG recordings from muscles undergoing vibratory stimulation. Results confirm the need of motion artifact filtering for raw EMG recordings during stimulation and strongly suggests to avoid EMG rectification that significantly alters the spectrum characteristics
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