215 research outputs found
Avaliação do método capacitivo de placas coplanares para determinação de umidade dos grãos de soja em movimento
Resumo: A medição do teor de umidade de grãos é um processo de fundamental importância para a cadeia produtiva da soja e outros cultivares. A quantidade de água contida nos grãos é determinante, desde a fase de colheita da soja, para garantir a sua conservação, qualidade e preço final. Diversos métodos de medida podem ser utilizados para determinar a umidade dos grãos de soja. Os métodos diretos são mais precisos, porém dispendiam muito tempo para se determinar a quantidade de água contida nos grãos, não sendo, portanto, um método viável para um sistema de medição em malha-fechada. Os métodos indiretos, baseados na correlação de grandezas elétricas com a variação da quantidade de água contida nos grãos, são os mais utilizados, com medidores práticos já desenvolvidos e estudos apresentando resultados cada vez mais promissores. O método capacitivo é um dos métodos indiretos mais conhecidos, pois a medida capacitiva apresenta boa estabilidade e correlação com o teor de umidade dos grãos de soja. Este trabalho analisa a aplicação de um sensor capacitivo de placas coplanares para realizar a medida do teor de umidade dos grãos de soja em movimento, simulando-se as condições de movimentação dos grãos em um secador. O estudo visa estimar os desvios que a movimentação dos grãos causa no processo de medida. Para desenvolver este trabalho, foi projetado um sensor de placas coplanares a partir de simulações utilizando o Método dos Elementos Finitos no DomÃnio do Tempo. Foram medidos os parâmetros de impedância do sensor com a soja em movimento e parada, em diferentes nÃveis de umidade e frequências de medição. O sensor capacitivo de placas coplanares desenvolvido neste trabalho, mostrou-se uma boa opção para se determinar a umidade de grãos de soja em movimento
Integrating Machine Learning and Multiscale Modeling: Perspectives, Challenges, and Opportunities in the Biological, Biomedical, and Behavioral Sciences
Fueled by breakthrough technology developments, the biological, biomedical,
and behavioral sciences are now collecting more data than ever before. There is
a critical need for time- and cost-efficient strategies to analyze and
interpret these data to advance human health. The recent rise of machine
learning as a powerful technique to integrate multimodality, multifidelity
data, and reveal correlations between intertwined phenomena presents a special
opportunity in this regard. However, classical machine learning techniques
often ignore the fundamental laws of physics and result in ill-posed problems
or non-physical solutions. Multiscale modeling is a successful strategy to
integrate multiscale, multiphysics data and uncover mechanisms that explain the
emergence of function. However, multiscale modeling alone often fails to
efficiently combine large data sets from different sources and different levels
of resolution. We show how machine learning and multiscale modeling can
complement each other to create robust predictive models that integrate the
underlying physics to manage ill-posed problems and explore massive design
spaces. We critically review the current literature, highlight applications and
opportunities, address open questions, and discuss potential challenges and
limitations in four overarching topical areas: ordinary differential equations,
partial differential equations, data-driven approaches, and theory-driven
approaches. Towards these goals, we leverage expertise in applied mathematics,
computer science, computational biology, biophysics, biomechanics, engineering
mechanics, experimentation, and medicine. Our multidisciplinary perspective
suggests that integrating machine learning and multiscale modeling can provide
new insights into disease mechanisms, help identify new targets and treatment
strategies, and inform decision making for the benefit of human health
The Structure of Episodic Memory: Ganeri's ‘Mental Time Travel and Attention’
We offer a framework for assessing what the structure of episodic memory might be, if one accepts the Buddhist denial of persisting selves. This paper is a response to Jonardon Ganeri's paper "Mental time travel and attention", which explores Buddhaghosa's ideas about memory. (It will eventually be published with a reply by Ganeri)
Colour reconnection in e+e- -> W+W- at sqrt(s) = 189 - 209 GeV
The effects of the final state interaction phenomenon known as colour
reconnection are investigated at centre-of-mass energies in the range sqrt(s) ~
189-209 GeV using the OPAL detector at LEP. Colour reconnection is expected to
affect observables based on charged particles in hadronic decays of W+W-.
Measurements of inclusive charged particle multiplicities, and of their angular
distribution with respect to the four jet axes of the events, are used to test
models of colour reconnection. The data are found to exclude extreme scenarios
of the Sjostrand-Khoze Type I (SK-I) model and are compatible with other
models, both with and without colour reconnection effects. In the context of
the SK-I model, the best agreement with data is obtained for a reconnection
probability of 37%. Assuming no colour reconnection, the charged particle
multiplicity in hadronically decaying W bosons is measured to be (nqqch) =
19.38+-0.05(stat.)+-0.08 (syst.).Comment: 30 pages, 9 figures, Submitted to Euro. Phys. J.
Search for R-Parity Violating Decays of Scalar Fermions at LEP
A search for pair-produced scalar fermions under the assumption that R-parity
is not conserved has been performed using data collected with the OPAL detector
at LEP. The data samples analysed correspond to an integrated luminosity of
about 610 pb-1 collected at centre-of-mass energies of sqrt(s) 189-209 GeV. An
important consequence of R-parity violation is that the lightest supersymmetric
particle is expected to be unstable. Searches of R-parity violating decays of
charged sleptons, sneutrinos and squarks have been performed under the
assumptions that the lightest supersymmetric particle decays promptly and that
only one of the R-parity violating couplings is dominant for each of the decay
modes considered. Such processes would yield final states consisting of
leptons, jets, or both with or without missing energy. No significant
single-like excess of events has been observed with respect to the Standard
Model expectations. Limits on the production cross- section of scalar fermions
in R-parity violating scenarios are obtained. Constraints on the supersymmetric
particle masses are also presented in an R-parity violating framework analogous
to the Constrained Minimal Supersymmetric Standard Model.Comment: 51 pages, 24 figures, Submitted to Eur. Phys. J.
Measurement of the Hadronic Photon Structure Function F_2^gamma at LEP2
The hadronic structure function of the photon F_2^gamma is measured as a
function of Bjorken x and of the factorisation scale Q^2 using data taken by
the OPAL detector at LEP. Previous OPAL measurements of the x dependence of
F_2^gamma are extended to an average Q^2 of 767 GeV^2. The Q^2 evolution of
F_2^gamma is studied for average Q^2 between 11.9 and 1051 GeV^2. As predicted
by QCD, the data show positive scaling violations in F_2^gamma. Several
parameterisations of F_2^gamma are in agreement with the measurements whereas
the quark-parton model prediction fails to describe the data.Comment: 4 pages, 2 figures, to appear in the proceedings of Photon 2001,
Ascona, Switzerlan
Conference of Microelectronic Research 1990
https://scholarworks.rit.edu/meec_archive/1003/thumbnail.jp
Modulation of the β-Catenin Signaling Pathway by the Dishevelled-Associated Protein Hipk1
BACKGROUND:Wnts are evolutionarily conserved ligands that signal through beta-catenin-dependent and beta-catenin-independent pathways to regulate cell fate, proliferation, polarity, and movements during vertebrate development. Dishevelled (Dsh/Dvl) is a multi-domain scaffold protein required for virtually all known Wnt signaling activities, raising interest in the identification and functions of Dsh-associated proteins. METHODOLOGY:We conducted a yeast-2-hybrid screen using an N-terminal fragment of Dsh, resulting in isolation of the Xenopus laevis ortholog of Hipk1. Interaction between the Dsh and Hipk1 proteins was confirmed by co-immunoprecipitation assays and mass spectrometry, and further experiments suggest that Hipk1 also complexes with the transcription factor Tcf3. Supporting a nuclear function during X. laevis development, Myc-tagged Hipk1 localizes primarily to the nucleus in animal cap explants, and the endogenous transcript is strongly expressed during gastrula and neurula stages. Experimental manipulations of Hipk1 levels indicate that Hipk1 can repress Wnt/beta-catenin target gene activation, as demonstrated by beta-catenin reporter assays in human embryonic kidney cells and by indicators of dorsal specification in X. laevis embryos at the late blastula stage. In addition, a subset of Wnt-responsive genes subsequently requires Hipk1 for activation in the involuting mesoderm during gastrulation. Moreover, either over-expression or knock-down of Hipk1 leads to perturbed convergent extension cell movements involved in both gastrulation and neural tube closure. CONCLUSIONS:These results suggest that Hipk1 contributes in a complex fashion to Dsh-dependent signaling activities during early vertebrate development. This includes regulating the transcription of Wnt/beta-catenin target genes in the nucleus, possibly in both repressive and activating ways under changing developmental contexts. This regulation is required to modulate gene expression and cell movements that are essential for gastrulation
Neural representations of the sense of self
The brain constructs representations of what is sensed and thought about in the
form of nerve impulses that propagate in circuits and network assemblies
(Circuit Impulse Patterns, CIPs). CIP representations of which humans are
consciously aware occur in the context of a sense of self. Thus, research on
mechanisms of consciousness might benefit from a focus on how a conscious sense
of self is represented in brain. Like all senses, the sense of self must be
contained in patterns of nerve impulses. Unlike the traditional senses that are
registered by impulse flow in relatively simple, pauci-synaptic projection
pathways, the sense of self is a system- level phenomenon that may be generated
by impulse patterns in widely distributed complex and interacting circuits. The
problem for researchers then is to identify the CIPs that are unique to
conscious experience. Also likely to be of great relevance to constructing the
representation of self are the coherence shifts in activity timing relations
among the circuits. Consider that an embodied sense of self is generated and
contained as unique combinatorial temporal patterns across multiple neurons in
each circuit that contributes to constructing the sense of self. As with other
kinds of CIPs, those representing the sense of self can be learned from
experience, stored in memory, modified by subsequent experiences, and expressed
in the form of decisions, choices, and commands. These CIPs are proposed here to
be the actual physical basis for conscious thought and the sense of self. When
active in wakefulness or dream states, the CIP representations of self act as an
agent of the brain, metaphorically as an avatar. Because the selfhood CIP
patterns may only have to represent the self and not directly represent the
inner and outer worlds of embodied brain, the self representation should have
more degrees of freedom than subconscious mind and may therefore have some
capacity for a free-will mind of its own. S everal lines of evidence for this
theory are reviewed. Suggested new research includes identifying distinct
combinatorially coded impulse patterns and their temporal coherence shifts in
defined circuitry, such as neocortical microcolumns. This task might be
facilitated by identifying the micro-topography of field-potential oscillatory
coherences among various regions and between different frequencies associated
with specific conscious mentation. Other approaches can include identifying the
changes in discrete conscious operations produced by focal trans-cranial
magnetic stimulation
Cross-Coupling of α-carbonyl sulfoxonium ylides with C-H bonds
The functionalization of carbon-hydrogen bonds in non-nucleophilic substrates using α-carbonyl sulfoxonium ylides has not been so far investigated, despite the potential safety advantages that those reagents would provide over diazo compounds or their in situ precursors. We describe the cross-coupling reactions of sulfoxonium ylides with C(sp2)-H bond of arenes and heteroarenes in the presence of a rhodium catalyst. The reaction proceeds by a succession of C-H activation, migratory insertion of the ylide into the carbon-metal bond and protonation, the last step being turnover-limiting. The method is applied to the synthesis of benz[c]acridines when allied to an iridium-catalyzed dehydrative cyclization
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