2,796 research outputs found
-boundedness properties for the maximal operators for semigroups associated with Bessel and Laguerre operators
In this paper we prove that the generalized (in the sense of Caffarelli and
Calder\'on) maximal operators associated with heat semigroups for Bessel and
Laguerre operators are weak type
(1,1). Our results include other known ones and our proofs are simpler than
the ones for the known special cases.Comment: 8 page
A Rule-Based Expert System for Teachers’ Certification in the Use of Learning Management Systems
In recent years and accelerated by the arrival of the COVID-19 pandemic, Learning Management Systems (LMS) are increasingly used as a complement to university teaching. LMS provide an important number of resources and activities that teachers can freely select to complement their teaching, which means courses with different usage patterns difficult to characterize. This study proposes an expert system to automatically classify courses and certify teachers’ LMS competence from LMS logs. The proposed system uses clustering to stablish the classification scheme. From the output of this algorithm, it defines the rules used to classify courses. Data registered from a university virtual campus with 3,303 courses and two million interactive events have been used to obtain the classification scheme and rules. The system has been validated against a group of experts. Results show that it performs successfully. Therefore, it can be concluded that the system can automatically and satisfactorily evaluate and certify the teachers’ LMS competence evidenced in their courses
Intoxicação por cobre em ovinos na região de Franca - SP alimentados com ração de bovinos de leite
Intoxicação crĂ´nica por cobre foi observada em um rebanho de 20 ovinos no municĂpio de Franca, SĂŁo Paulo. TrĂŞs meses apĂłs o inĂcio do arraçoamento com feno e ração concentrada peletizada para bovinos de leite, seis animais apresentaram anorexia, icterĂcia severa e urina marrom escura, e vieram a Ăłbito. Diagnosticou-se doença hemolĂtica com base em sinais clĂnicos, alterações macroscĂłpicas observadas na necropsia e observações histolĂłgicas. Ă€ necropsia todos os ovinos apresentaram icterĂcia severa, fĂgado amarelado com padrĂŁo lobular evidente e rins escuros. As principais alterações histolĂłgicas incluĂram necrose hepática periacinar e nefrose hemoglobinĂşrica. AcĂşmulos de cobre foram demonstrados nos hepatĂłcitos e macrĂłfagos pela coloração rodamina e nĂveis elevados de cobre mediante espectrofotometria de absorção atĂ´mica no soro, fĂgado e rins de dois ovinos afetados e na ração fornecida
Displasia renal em um bezerro Limousin
Descreve-se um caso de displasia renal em um bezerro Limousin, macho, de quatro meses. O animal apresentava perda de peso, baixa taxa de crescimento, anorexia, apatia, diarrĂ©ia escura fĂ©tida e uremia, sem melhora apesar de tratamento. O bezerro foi sacrificado para interromper o sofrimento adicional e submetido Ă necropsia. Ao exame foi observado que os rins estavam pequenos, firmes, pálidos e com superfĂcie rugosa. A cápsula estava aderida Ă uma superfĂcie subcapsular irregular. O cĂłrtex tinha aparĂŞncia difusamente pálida e fibrosa e apresentava mĂşltiplos focos brancos de fibrose. A junção cĂłrtico-medular estava indistinta. O exame histologico dos rins revelou mĂşltiplos glomĂ©rulos imaturos com nĂşcleo perifĂ©rico, capilares inaparentes e padrĂŁo arbĂłreo. O cĂłrtex renal apresentou tĂşbulos primitivos com epitĂ©lio cubĂłide ou cilĂndrico envolvido por mesĂŞnquima corado somente pelo alcian blue e nĂŁo pelo tricrĂ´mico de Masson. Foi tambĂ©m observada leve fibrose intersticial na medula renal. Os rins mostravam estruturas em estágio inapropriado de desenvolvimento ou anĂ´malas
Perosomus elumbis in a sheep in Brazil
Perosomus elumbis designa um conjunto raro de anomalias congênitas que primariamente incluem agenesia parcial da medula espinhal e vértebras lombossacrais. O presente relato descreve a ocorrência da enfermidade em um ovino neonato no Brasil.Perosomus elumbis designates a set of rare abnormal congenital abnormalities that primarily includes partial agenesis of spinal cord and lumbosacral vertebrae. The present paper reports the occurrence of the disease in a neonate sheep in Brazil
Sequestration and biosynthesis of cyanogenic glucosides in passion vine butterflies and consequences for the diversification of their host plants.
The colorful heliconiine butterflies are distasteful to predators due to their content of defense compounds called cyanogenic glucosides (CNglcs), which they biosynthesize from aliphatic amino acids. Heliconiine larvae feed exclusively on Passiflora plants where ~30 kinds of CNglcs have been reported. Among them, some CNglcs derived from cyclopentenyl glycine can be sequestered by some Heliconius species. In order to understand the evolution of biosynthesis and sequestration of CNglcs in these butterflies and its consequences for their arms race with Passiflora plants, we analyzed the CNglc distribution in selected heliconiine and Passiflora species. Sequestration of cyclopentenyl CNglcs is not an exclusive trait of Heliconius, since these compounds were present in other heliconiines such as Philaethria, Dryas and Agraulis, and in more distantly related genera Cethosia and Euptoieta. Thus, it is likely that the ability to sequester cyclopentenyl CNglcs arose in an ancestor of the Heliconiinae subfamily. Biosynthesis of aliphatic CNglcs is widespread in these butterflies, although some species from the sara-sapho group seem to have lost this ability. The CNglc distribution within Passiflora suggests that they might have diversified their cyanogenic profile to escape heliconiine herbivory. This systematic analysis improves our understanding on the evolution of cyanogenesis in the heliconiine-Passiflora system
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