19,966 research outputs found
O crescimento recente do agronegócio brasileiro.
Carta da Agricultur
Diagnóstico, planejamento ecológico e análise da adubação verde nos agroecossistemas de São Carlos, SP.
bitstream/CNPDIA/9822/1/CiT04_96.pd
A 'p-n' diode with hole and electron-doped lanthanum manganite
The hole-doped manganite La0.7Ca0.3MnO3 and the electron-doped manganite
La0.7Ce0.3MnO3 undergo an insulator to metal transition at around 250 K, above
which both behave as a polaronic semiconductor. We have successfully fabricated
an epitaxial trilayer (La0.7Ca0.3MnO3/SrTiO3/La0.7Ce0.3MnO3), where SrTiO3 is
an insulator. At room temperature, i.e. in the semiconducting regime, it
exhibits asymmetric current-voltage (I-V) characteristics akin to a p-n diode.
The observed asymmetry in the I-V characteristics disappears at low
temperatures where both the manganite layers are metallic. To the best of our
knowledge, this is the first report of such a p-n diode, using the polaronic
semiconducting regime of doped manganites.Comment: PostScript text and 2 figures, to be published in Appl. Phys. Lett
Development of a low cost digital energy meter
This paper presents a versatile low
cost equipment that allows simultaneous display
of usually required measurements in electric
circuits, like true RMS (Root Mean Square)
values of mains voltage and current, line
frequency, power factor, active, reactive and
apparent power, and energy.
The equipment is based on a microcontroller
that interfaces current and voltage transducers
through 16 bits sigma-delta ADCs (Analog to
Digital Converters). The microcontroller
controls the periodic acquisition of the measured
signal waveforms, makes the respective
calculations and presents the results on an
alphanumeric display. The equipment also
provides a serial port that enables the
communication with other devices allowing the
interface through a SCADA (Supervisory Control
and Data Acquisition) system
Bloqueio Epidural Torácico em Cirurgia de Nuss: Caso de Sucesso
Os autores descrevem o caso c1ínico de um adolescente com o diagnóstico de pectus excavatum grave, submetido a cirurgia de Nuss sob controlo toracoscópico. Realizou-se anestesia combinada, com cateter epidural torácico que permitiu um periodo intra e pós-operatório estável, sem intercorrências e sem necessidade de suplementação analgésica
DSOL: a declarative approach to self-adaptive service orchestrations
Service oriented computing (SOC) has brought a simplification in the way distributed applications can be built. Mainstream approaches, however, failed to support dynamic, self-managed compositions that would empower even non-technical users to build their own orchestrations. Indeed, because of the changeable world in which they are embedded, service compositions must be able to adapt to changes that may happen at run-time. Unfortunately, mainstream SOC languages, like BPEL and BPMN, make it quite hard to develop such kind of self-adapting orchestrations. We claim that this is mostly due to the imperative programming paradigm they are based on. To overcome this limitation we propose a radically different, strongly declarative approach to model service orchestration, which is easier to use and results in more flexible and self-adapting orchestrations. An ad-hoc engine, leveraging well-known planning techniques, interprets such models to support dynamic service orchestration at run-time
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