927 research outputs found
Análise do uso de tecnologias em estabelecimentos agropecuários por meio dos Ãndices de Moran global e local.
Este artigo apresenta uma aplicação de técnica de análise exploratória de dados espaciais sobre dados de uso de tecnologias por parte de estabelecimentos agropecuários do PaÃs, com a finalidade de prospectar e justificar possÃveis relações espaciais relacionadas ao uso das tecnologias. Os dados foram obtidos no Censo Agropecuário de 2006, e foram analisados por meio dos Ãndices de Moran global e local. O trabalho apresenta uma breve revisão bibliográfica sobre a análise exploratória de dados espaciais e dos principais Ãndices utilizados. Os resultados, visualizados no BoxMap, do diagrama de espalhamento de Moran e do MoranMap mostram que, para a maioria das caracterÃsticas analisadas, há alta correlação espacial no uso de tecnologias nos municÃpios brasileiros, e que essa concentração está relacionada à produção de commodities do mercado internacional. Os resultados sugerem que, para algumas regiões do PaÃs, deve-se elaborar uma análise em escala menor, para identificar possÃveis grupos (clusters) dentro dos estados ou de mesorregiões produtoras. O trabalho mostra que, para uma análise preliminar da distribuição espacial do uso de tecnologia na agropecuária, o uso do software TerraView mostrou-se satisfatório, e, por isso, sugere-se que seja adotado em estudos mais profundos com esses indicadores
Earth conductivity structures and their effects on geomagnetic induction in pipelines
Anomalous, large pipe-to-soil potentials (PSP) have been observed along a natural gas pipeline in eastern Ontario, Canada, where there is a major geological contact between the highly resistive rocks of the Precambrian Shield to the west and the more conductive Paleozoic sediments to the east. This study tested the hypothesis that large variations of PSP are related to lateral changes of Earth conductivity under the pipeline. Concurrent and co-located PSP and magnetotelluric (MT) geophysical data were acquired in the study area. Results from the MT survey were used to model PSP variations based on distributed-source transmission line theory, using a spatially-variant surface geoelectric field. Different models were built to investigate the impact of different subsurface features. Good agreement between modelled and observed PSP was reached when impedance peaks related to major changes of subsurface geological conditions were included. The large PSP could therefore be attributed to the presence of resistive intrusive bodies in the upper crust and/or boundaries between tectonic terranes. This study demonstrated that combined PSP-MT investigations are a useful tool in the identification of potential hazards caused by geomagnetically induced currents in pipelines
Alteration effects of volcanic ash in seawater: Anomalous Y/Ho ratios in coastal waters of the Central Mediterranean sea
This paper presents the results of a study based on data collected during the oceanographic cruise ANSIC 2001 carried out in the Ionian Sea during the explosive activity of Mount Etna in the summer of 2001. Anomalous low values of Y/Ho ratios in seawater suggest extensive scavenging processes on the surfaces of smectitic alteration products, with Y and Ho fractionation controlled by the differences in their electronic configurations and behaviour during solution/surface complexation equilibria. These processes can also be traced through the presence of significant tetrad effects recorded in the chondrite-normalised Rare Earth Elements and Yttrium (YREEs) patterns of suspended particulate matter. This suggests that the preferential Y scavenging from seawater is due to the formation of inner-sphere complexes with OH- groups on montmorillonite crystal surfaces. The preliminary results of kinetic experiments of YREE released from volcanic ash to coexisting seawater, and the related effects on Y/Ho ratios and Ce anomalies, are consistent with the fractionation of Light Rare Earth Elements (LREEs) with respect to Heavy Rare Earth Elements (HREEs) observed in dissolved phase. They suggest a behaviour of Y similar to that reported for LREEs, particularly for Ce and Pr. © 2007 Elsevier Ltd. All rights reserved
Symmetric derivatives of parametrized quantum circuits
Symmetries are crucial for tailoring parametrized quantum circuits to
applications, due to their capability to capture the essence of physical
systems. In this work, we shift the focus away from incorporating symmetries in
the circuit design and towards symmetry-aware training of variational quantum
algorithms. For this, we introduce the concept of projected derivatives of
parametrized quantum circuits, in particular the equivariant and covariant
derivatives. We show that the covariant derivative gives rise to the quantum
Fisher information and quantum natural gradient. This provides an operational
meaning for the covariant derivative, and allows us to extend the quantum
natural gradient to all continuous symmetry groups. Connecting to traditional
particle physics, we confirm that our covariant derivative is the same as the
one introduced in physical gauge theory. This work provides tools for tailoring
variational quantum algorithms to symmetries by incorporating them locally in
derivatives, rather than into the design of the circuit.Comment: 22+20 pages, 6+1 figure
Installazione di un radiometro nell'area sommitale del vulcano Etna
Le tecniche di telerilevamento satellitare e da terra per la stima della temperatura di anomalie termiche
delle superfici vulcaniche, della loro variazione nel tempo e per individuare attività parossistiche o l’inizio di
una fase di colate di lava, sono ormai entrate a far parte della sorveglianza e del monitoraggio vulcanologico
[es. Francis, 1979; Geraci et al., 1985; Lombardo et al., 2011; Spampinato et al., 2011]. I sensori in una
banda spettrale dell’infrarosso quali radiometri e telecamere termiche, utilizzati in prossimità di bocche
eruttive, hanno fornito cospicue quantità di dati di temperatura della superficie di corpi magmatici (colate
laviche, laghi di lava, duomi lavici), plume vulcanici, fumarole, registrati a distanza di totale sicurezza
[Spampinato et al., 2011]. In particolare, i radiometri, sia portatili che installati in stazioni permanenti, oltre
che fornire dati da confrontare con misure geochimiche, permettono l’acquisizione di dati di temperatura ad
elevata frequenza, tali da essere messi in relazione con le misure derivate da osservazioni geofisiche quali ad
esempio il tremore sismico [es. Harris e Ripepe, 2007; Branan et al., 2008].In questo lavoro si descrivono i dettagli dell’installazione di una stazione radiometrica collocata
nell’area sommitale dell’Etna in zona Belvedere, nel sito già utilizzato da una stazione multiparametrica (con
sensori sismici e infrasonici) e denominato EBEL. Si descrivono anche la metodologia di trasmissione dati in
continuo, il trattamento del dato convertito in temperatura apparente nel campo di vista del radiometro, la
visualizzazione in tempo quasi reale del dato e la sua diffusione tramite WEB
HoBi-Like Pestivirus and Its Impact on Cattle Productivity
The clinical features and economic impact of the infection caused by an emerging group of pestiviruses, namely HoBi-like pestivirus, in a cattle herd of southern Italy are reported. In 2011, the virus was first associated with respiratory disease, causing an abortion storm after 1 year and apparently disappearing for the following 3 years after persistently infected calves were slaughtered. However, in 2014, reproductive failures and acute gastroenteritis were observed in the same herd, leading to a marked decrease of productivity. A HoBi-like strain closely related to that responsible for previous outbreaks was detected in several animals. Application of an intensive eradication programme, based on the detection and slaughtering of HoBi-like pestivirus persistently infected animals, resulted in a marked improvement of the productive performances
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