1,284 research outputs found
Lagarta-dos-cafezais: o caso de Rondônia.
Nesta publicação verificou-se a existência de 64 propriedades com 618 hectares afetados pelo ataque da lagarta-dos-cafezais no município de Cacoal-RO e as medidas de controle adotadas para conter a expansão de E. imperialis com a redução significativa da área atacada.bitstream/item/72102/1/0000004037-ct68-lagartadoscafezais.pd
Prognose de crescimento volumétrico individual de árvores de Eucalyptus, em povoamentos na Região Centro Sul.
A prognose do crescimento volumétrico individual foi realizada com dados de um ensaio de adubação de Eucalyptus dunnii e de competição de espécies incluindo E. bicostata, E. “cambiju” (híbrido natural), E. deanei e E. viminalis, implantados em Vila Velha, Ponta Grossa, Paraná. Utilizou-se para este estudo o método das regressões sucessivas modificado para a forma exponencial, incluindo como constante o volume aos três anos de idade. Os coeficientes de correlação obtidos, os erros padrão das estimativas e a distribuição de resíduos, para os modelos propostos no presente estudo, demonstraram a possibilidade do uso do método das regressões sucessivas, modificado para a forma exponencial, com a inclusão do volume na idade base de três anos, e a expectativa de sobrevivência ao longo da rotação, para a prognose de volumes individuais de árvores de espécies de Eucalyptus. A precisão da prognose é alta para espécies bem adaptadas, que apresentem sobrevivência elevada, até o final da rotação por exemplo E.deanei e E. dunnii. O E. “cambiju” apresentou acentuado decréscimo de sobrevivência ao longo da rotação. Neste caso, para maior precisão, foi necessário a inclusão no modelo do valor da recíproca da sobrevivência. Populações com baixo potencial de crescimento, apresentam volumes individuais e populacionais baixos, mesmo com alta sobrevivência. O E. viminalis e o E. cambiju, ambos com baixa sobrevivência ao final da rotação, apresentaram volumes individuais mais elevados que as outras espécies, em idades mais elevadas, exceto E. dunnii
Evidence of fractal structures in hadrons
This study focuses on the presence of (multi)fractal structures in confined
hadronic matter through the momentum distributions of mesons produced in
proton-proton collisions between 23 GeV and 63 GeV. The analysis demonstrates
that the -exponential behaviour of the particle momentum distributions is
consistent with fractal characteristics, exhibiting fractal structures in
confined hadronic matter with features similar to those observed in the
deconfined quark-gluon plasma (QGP) regime. Furthermore, the systematic
analysis of meson production in hadronic collisions at energies below 1 TeV
suggests that specific fractal parameters are universal, independently of
confinement or deconfinement, while others may be influenced by the quark
content of the produced meson. These results pave the way for further research
exploring the implications of fractal structures on various physical
distributions and offer insights into the nature of the phase transition
between confined and deconfined regimes.Comment: 23 pages, 11 figures, supplementary materia
On small-noise equations with degenerate limiting system arising from volatility models
The one-dimensional SDE with non Lipschitz diffusion coefficient is widely
studied in mathematical finance. Several works have proposed asymptotic
analysis of densities and implied volatilities in models involving instances of
this equation, based on a careful implementation of saddle-point methods and
(essentially) the explicit knowledge of Fourier transforms. Recent research on
tail asymptotics for heat kernels [J-D. Deuschel, P.~Friz, A.~Jacquier, and
S.~Violante. Marginal density expansions for diffusions and stochastic
volatility, part II: Applications. 2013, arxiv:1305.6765] suggests to work with
the rescaled variable : while
allowing to turn a space asymptotic problem into a small- problem
with fixed terminal point, the process satisfies a SDE in
Wentzell--Freidlin form (i.e. with driving noise ). We prove a
pathwise large deviation principle for the process as
. As it will become clear, the limiting ODE governing the
large deviations admits infinitely many solutions, a non-standard situation in
the Wentzell--Freidlin theory. As for applications, the -scaling
allows to derive exact log-asymptotics for path functionals of the process:
while on the one hand the resulting formulae are confirmed by the CIR-CEV
benchmarks, on the other hand the large deviation approach (i) applies to
equations with a more general drift term and (ii) potentially opens the way to
heat kernel analysis for higher-dimensional diffusions involving such an SDE as
a component.Comment: 21 pages, 1 figur
Prevalence And Clinical Significance Of Potential Drug-drug Interactions In Diabetic Patients Attended In A Tertiary Care Outpatient Center, Brazil
The aim of this study is to investigate the prevalence of potential drug-drug interactions (PDDIs), as well as classifying them in relation to level of severity, scientific evidence, time of onset, and potential clinical impact in adult and older adult patients with diabetes mellitus 2 (DM2). This cross-sectional study was conducted in a tertiary care outpatient center. The consecutive sample was made up of 140 patients with DM2. The Anatomical-Therapeutic-Chemical Classification was used for classifying the classes of medications. The PDDIs were analyzed using the DRUG-REAXA (R) system. The relationships between PDDI and the associated factors were ascertained using a multiple logistic regression model. The prevalence of total PDDI was 75 %, and the prevalence of major severity PDDI was 20.7 %. Simvastatin (30.8 %), captopril/enalapril (12.8 %), and oral anti-diabetics/insulin (12.8 %) were the medications which were most involved in the major PDDI, bringing relevant potential clinical impacts such as rhabdomyolysis, hyperkalemia, and important glycemic alterations. Polypharmacy was associated with PDDI (adjusted odds ratio = 10.46, 95 % confidence interval = 4.10-26.71). Diabetics were highly exposed to clinically significant PDDI. It is important that health professionals should be aware of the risks related to PDDI, so that measures may be implemented in order to assure safe care for the patient.36328328
Elastic electron scattering from 3-hydroxytetrahydrofuran: experimental and theoretical studies
We report the results of measurements and calculations for elastic electron scattering from 3-hydroxytetrahydrofuran (C4H8O2). The measurements are performed with a crossed electron-target beam apparatus and the absolute cross-sections are determined using the relative flow technique. The calculations are carried out using the Schwinger multichannel method in the static-exchange plus polarization (SEP) approximation. A set of angular differential cross-sections (DCS) is provided at five incident energies (6.5, 8, 10, 15 and 20 eV) over an angular range of 20–130°, and the energy dependence of the elastic DCS at a scattering angle of 120° is also presented. Integral elastic and elastic momentum transfer cross-sections have also been derived and calculated. The results are compared with those of recent measurements and calculations for the structurally similar molecule tetrahydrofuran (C4H8O)
Utilização da cianamida hidrogenada e óleo mineral na brotação e floração de pessegueiro.
bitstream/item/43867/1/boletim-33.pd
A crise social desenhada pelas crianças: imaginação e conhecimento social
A crise social e económica que tem atingido o mundo desde 2008, com efeitos especialmente sentidos nos países do Sul da Europa, causou impactos fortes e visíveis na infância, como o aumento das taxas efetivas e de risco de pobreza e a vulnerabilidade e a exposição a fatores de risco social e de perda consistente de direitos. A análise dessas incidências tem vindo a ser trabalhada num conjunto de relatórios nacionais e internacionais, de ONG’s e estudos académicos. No entanto, poucos estudos têm dedicado atenção ao modo como a interpretação das representações das crianças sobre a crise é feita e sobre as expressões específicas que estas assumem na sua vida quotidiana. As crianças são capazes de observar os modos como a crise impacta o seu próprio grupo geracional, bem como os adultos que mais lhe são próximos. Da mesma forma, promovem interpretações económicas sobre os fenómenos, sejam elas mais “ingénuas” ou mais complexas. Este artigo incide sobre as representações das crianças sobre a crise social e económica em Portugal. São especialmente analisadas narrativas gráficas produzidas por crianças oriundas de classes trabalhadoras, com idades compreendidas entre os 6 e os 10 anos de idade. Por meio dessas narrativas, as crianças constroem formas visuais a partir da sua imaginação sobre a sua condição. Assim, a imaginação das crianças é um modo de acesso ao conhecimento na sociedade onde se inserem e aos seus modos próprios de compreensão de realidades complexas.The social and economic crisis that has hit the world since 2008, with effects
strongly felt in the countries of Southern Europe, has had fierce and
visible impacts in childhood with the increase of the effective rates, the risk
of poverty and vulnerability, and the exposure to factors of social risk and
consistent loss of rights. The analysis of these incidents has been worked on
in a series of national and international reports from NGOs and academic
studies. However, few studies have devoted attention to the way in which
the interpretation of the representations of children about the crisis is made
and the specific expressions that they assume in their daily lives. Children
are able to observe the ways in which the crisis affects their own generational
group as well as the adults closest to them. In the same way, they promote
economic interpretations of phenomena, whether “naïve” or more complex.
This article focuses on the representations of children about the social and
economic crisis in Portugal. Graphical narratives produced by children from
working classes, aged between 6 and 10 years old, are given focus. From
these narratives, children construct visual forms from their imagination about
their social condition. Thus, the child’s imagination is a way of accessing
knowledge in the society they belong to and their own way of understanding
complex realities.CIEC - Centro de Investigação em Estudos da Criança, IE, UMinho (UI 317 da FCT), Portugalinfo:eu-repo/semantics/publishedVersio
Theory and computation of covariant Lyapunov vectors
Lyapunov exponents are well-known characteristic numbers that describe growth
rates of perturbations applied to a trajectory of a dynamical system in
different state space directions. Covariant (or characteristic) Lyapunov
vectors indicate these directions. Though the concept of these vectors has been
known for a long time, they became practically computable only recently due to
algorithms suggested by Ginelli et al. [Phys. Rev. Lett. 99, 2007, 130601] and
by Wolfe and Samelson [Tellus 59A, 2007, 355]. In view of the great interest in
covariant Lyapunov vectors and their wide range of potential applications, in
this article we summarize the available information related to Lyapunov vectors
and provide a detailed explanation of both the theoretical basics and numerical
algorithms. We introduce the notion of adjoint covariant Lyapunov vectors. The
angles between these vectors and the original covariant vectors are
norm-independent and can be considered as characteristic numbers. Moreover, we
present and study in detail an improved approach for computing covariant
Lyapunov vectors. Also we describe, how one can test for hyperbolicity of
chaotic dynamics without explicitly computing covariant vectors.Comment: 21 pages, 5 figure
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