683 research outputs found
Determinants in the on-line distribution of digital content: an exploratory analysis
This article shows the phases – and discusses the results – of an empirical analysis addressing the legal
business models that are adopted online to distribute digital content
HELIUM ISOTOPES AND TECTONICS IN SOUTHERN ITALY
Geodynamic evolution of southern Italy can
be understood within the framework of the Mediterranean-
Alpine System. Subduction of a plate along the Sicily-
Calabrian forearc under the Tyrrhenian Sea has been suggested
by many geophysicists, although it is not yet confirmed
and remains somewhat controversial. Helium isotope
ratios provide useful information on the geotectonic structure
of the region. We report here the 3He/4He ratios of
terrestrial gas samples from southern Italy. The observed
3He/4He ratios are relatively high in the Eolian volcanic arc
region and low in the other areas. Dichotomous explanations
are presented. Firstly volcanic arc-forearc hypothesis
suggests the subduction along the Sicily-Calabrian forearc.
Secondly horizontal transport hypothesis is described based
on the relationship between the ratios and radial distance
from the recent spreading basin in Southern Tyrrhenian Sea
Electron spin relaxation in organic semiconductors probed through muSR
Muon spin spectroscopy and in particular the avoided level crossing technique
is introduced, with the aim of showing it as a very sensitive local probe for
electron spin relaxation in organic semiconductors. Avoided level crossing data
on TMS-pentacene at different temperatures are presented, and they are analysed
to extract the electron spin relaxation rate, that is shown to increase on
increasing the temperature from 0.02 MHz to 0.33 MHz at 3 K and 300 K
respectively.Comment: International Conference TSN2010 "Trends in spintronics and
nanomagnetism
Um mecanismo para prover interoperalidade entre ORBs com suporte a transparencia de relocação
Orientador: Edmundo Roberto Mauro MadeiraDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de ComputaçãoResumo: A capacidade de sistemas heterogêneos cooperarem é uma necessidade atual que vem se impondo cada vez mais, principalmente pelo rápido desenvolvimento da tecnologia de processamento distribuÃdo, obrigando a busca de soluções mais apropriadas. Nesse contexto, a especificação CORBA (Common Object Request Broker Architecture) apresenta uma arquitetura que permite a interoperabilidade entre aplicações em ambientes distribuÃdos heterogêneos. Entretanto, pela sua grande flexibilidade nas decisões de implementação, surgem problemas para estender essa interoperabilidade entre dois ORBs desenvolvidos por diferentes tecnologias. Nesta dissertação são discutidos esses problemas e suas respectivas soluções, sendo apresentado um conjunto de operações para suportar o mecanismo de interceptação, estendendo as transparências de acesso e localização, consideradas fundamentais num ambiente distribuÃdo, para além do escopo de um ORB. É proposta, também, uma forma para prover transparência de relocação, estendida para suportar interoperabilidade. Por fim, é descrita uma implementação desses mecanismos utilizando um protótipo aberto de ORB e uma implementação comercial, chamada ORBeline.Abstract: The ability of heterogeneous systems cooperate to problem's solutions is a real need that has been growing, due to the increasing development of the distributed processing technology. This need is driving the development of more suitable solutions. The CORBA (Common Object Request Broker Architecture) specification presents an architecture, which allows interoperability among heterogeneous distributed environment applications. However, because of the great flexibility offered in implementation decisions, many problems to extend interoperability between two ORBs developed by different technologies arise. This work discusses these problems and their solutions and presents a. set of operations to support an interception mechanism extending access and location transparencies, considered as fundamental for a distributed environment, to work beyond an ORB scope. A scheme to provide relocation transparency, extended to support interoperability is also proposed. Finally, an implementation of these mechanisms over an open ORB's prototype and ORBeline, a commercial product, is described.MestradoMestre em Ciência da Computaçã
Elemental and isotope covariation of noble gases in mineral phases from Etnean volcanics erupted during 2001–2005, and genetic relation with peripheral gas discharges
During 2001–2005, Mount Etna was characterized by intense eruptive activity involving the emission of
petrologically different products from several vents, which involved at least two types of magma with
different degrees of evolution. We investigated the ratios and abundances for noble-gas isotopes in fluid
inclusions trapped in olivines and pyroxenes in the erupted products. We confirm that olivine has the most
efficient crystalline structure for preserving the pristine composition of entrapped gases, while pyroxene can
suffer diffusive He loss. Both the minerals also experience noble gas air contamination after eruption. Helium
isotopes of the products genetically linked to the two different magmas fall in the isotopic range typical of
the Etnean volcanism. This result is compatible with the metasomatic process that the Etnean mantle is
undergoing by fluids from the Ionian slab during the last ten kyr, as previously inferred by isotope and trace
element geochemistry. Significant differences were also observed among olivines of the same parental
magma that erupted throughout 2001–2005, with 3He/4He ratios moving from about 7.0 Ra in 2001
volcanites, to 6.6 Ra in 2004–2005 products. Changes in He abundances and isotope ratios were attributed to
variations in protracted degassing of the same magma bodies from the 2001 to the 2004–2005 events, with
the latter lacking any contribution of undegassed magma. The decrease in 3He/4He is similar to that found
from measurements carried out every fifteen days during the same period in gases discharged at the
periphery of the volcano. To our knowledge this is the first time that such a comparison has been performed
so in detail, and provides strong evidence of the real-time feeding of peripheral emissions by magmatic
degassing
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