Generalized Convolution Roots of Positive Definite Kernels on Complex Spheres

Convolution is an important tool in the construction of positive definite kernels on a manifold. This contribution provides conditions on an $L^2$-positive definite and zonal kernel on the unit sphere of $\mathbb{C}^q$ in order that the kernel can be recovered as a generalized convolution root of an equally positive definite and zonal kernel

Probing the cosmic-ray pressure in the Virgo Cluster and the origin of the very-high-energy gamma rays of M87 with H.E.S.S. and CTA

Das High Energy Stereoscopic System (H.E.S.S.) ist ein System von fünf atmosphärischen Cherenkov-Teleskopen (IACT) in Namibia. Die H.E.S.S. Teleskope sind empfindlich für sehr energiereiche (VHE) Gammastrahlen zwischen ~30 TeV und 100 TeV. Mit einer Entfernung von 16,5 Mpc ist Messier 87 (M87) eine der nächsten Radiogalaxien und beherbergt eines der massereichsten supermassiven Schwarzen Löcher, das Materie in einen Plasmastrahl relativistischer Teilchen emittiert. Der Strahl wird im Bereich des gesamten elektromagnetischen Spektrums beobachtet und untersucht. M87 befindet sich im Zentrum des Virgo-Galaxienhaufens, eines kühlen Galaxienhaufens, der von Gas gefüllt ist, das in der Nähe des Zentrums kälter und in den Außenbereichen des Galaxienhaufens heißer ist. Gemäß der Cooling Flow (CF) Theorie kühlt das Plasma in Cool Core (CC) Haufen am Rand des Haufens ab und sinkt nach innen, wodurch die Sternentstehungsrate im Zentrum erhöht wird. Optische Messungen des Virgo Galaxienhaufens scheinen diesem Modell jedoch zu widersprechen. Als Heizmechanismus wird der aktive galaktische Kern Rückkopplungsmechanismus vorgeschlagen, der die Abkühlung des ICM ausgleicht und dessen CF vermeidet. Die kosmische Strahlung des Jets interagiert mit der ICM und erzeugt neutrale Pionen, die in Gammastrahlen zerfallen und ein nicht variables und ausgedehntes Gammastrahlensignal erzeugen. Allerdings konnten keine Gammastrahlen-Beobachtungen mit dem Pionenzerfall in dem Galaxienhaufen in Verbindung gebracht werden. In dieser Studie der H.E.S.S. Beobachtungen des niedrigen Strahl-Aktivitätszustands von M87 haben keine signifikante Ausdehnung der Emissionsregion gezeigt, woraus eine 3σ Obergrenze von 0.016° ≈ 4.6 kpc abgeleitet wurde. Das Verhältnis des Drucks in kosmischer Strahlung zur thermischen Strahlung ist auf <0.36 im Zentralregion beschränkt. Diese abgeleitete Obergrenze nimmt einen Gleichgewichtszustand zwischen den Erwärmungs und den Kühlprozessen an. Die neue Generation von IACTs, das Cherenkov Telescope Array Observatory (CTAO), wird eine unvergleichbare Empfindlichkeit und Winkelauflösung bieten. Um die langfristige Verfügbarkeit der Teleskope sicherzustellen, wurde ein auf Schwingungsmessungen basierendes Strukturüberwachungssystem entwickelt und zwischen 2019 und 2020 in Berlin am Prototyp des mittelgrossen Teleskopes erfolgreich getestet. CTAO wird in der Lage sein die Gammastrahlung des Virgo Haufens zu untersuchen und sie laut Simulationen und dem Steady-State-Modell innerhalb von ~210 h zu detektieren.The High Energy Stereoscopic System (H.E.S.S.) is an array of five Imaging Atmospheric Cherenkov Telescopes (IACTs) located in Namibia. The H.E.S.S. telescopes are sensitive to Very-High-Energy (VHE) gamma rays between ~30 TeV and ~100 TeV. At a distance of 16.5 Mpc Messier 87 (M87) is one of the closest radio-galaxies, hosting one of the most massive Super-Massive Black Hole, which accretes matter and launches an inclined jet of relativistic particles. The jet is detected and studied by radiation emitted through the entire electromagnetic spectrum. M87 is located at the very center of the Virgo galaxy cluster, a Cool Core (CC) cluster, characterized by an Intra-cluster Medium (ICM) that is colder close to the center and hotter towards the outskirts of the galaxy cluster. According to the Cooling Flow (CF) theory, the plasma in CC clusters cools in the outskirts of the cluster and falls inwards, increasing the star formation ratio in the region. However, optical measurements of the Virgo Cluster seem to contradict this model. The Active Galactic Nucleus (AGN) feedback mechanism is proposed as a heating mechanism, which counterbalances the cooling of the ICM and avoids its CF. The cosmic rays from the jet interact with the ICM producing neutral pions, which decay to gamma rays, forming a non-variable and extended gamma-ray signal. However, no gamma-ray observations could be associated with pion decay in galaxy clusters. In this work, deep H.E.S.S. observations of M87's low state are analyzed, and the results have shown no significant gamma-ray extension leading to a 3σ upper limit of 0.016° ≈ 4.6 kpc. The ratio of cosmic-ray pressure to thermal pressure XCR is constrained to < 0.36 at its maximum position, assuming a steady-state between the heating and the cooling processes. The new generation of IACTs, the Cherenkov Telescope Array Observatory (CTAO) will offer unprecedented sensitivity and angular resolution. To assure the long-term availability of the telescopes, a structure monitoring system based on vibration measurements was developed and successfully tested at the Medium-sized Telescope (MST) prototype between 2019 and 2020 in Berlin. CTAO should be able to probe the gamma-ray emission from the Virgo Cluster, and, according to simulations and to the steady-state model, significantly detect it after ≈ 210 h

Differentiable positive definite kernels on two-point homogeneous spaces

In this work we study continuous kernels on compact two-point homogeneous spaces which are positive definite and zonal (isotropic). Such kernels were characterized by R. Gangolli some forty years ago and are very useful for solving scattered data interpolation problems on the spaces. In the case the space is the d-dimensional unit sphere, J. Ziegel showed in 2013 that the radial part of a continuous positive definite and zonal kernel is continuously differentiable up to order ⌊(d−1)/2⌋ in the interior of its domain. The main issue here is to obtain a similar result for all the other compact two-point homogeneous spaces.CNPq (grant 141908/2015-7)FAPESP (grant 2014/00277-5

Livro-Pôster Portfólio para Ilustrador com base em Livros de Artista

PCC(graduação) - Universidade Federal de Santa Catarina. Centro de Comunicação e Expressão. Design.Neste projeto foi desenvolvido por meio do estudo teórico e prático em design e ilustração, um modelo impresso de portfólio para ilustradores com base em livros de artista. Por meio da aplicação da Metodologia de Projeto de Bruno Munari, adaptada para as necessidades deste PCC, o resultado propõe um modelo que pode ser replicado por outros ilustradores para a criação de portfólios que documentem e valorizem seu trabalho de modo criativo e através de um design estruturado

Spatial distribution and vegetation cover of urban green areas: case study in a tourist district of Maceió-Alagoas, Brazil

Se analizaron áreas verdes en un distrito turístico de la ciudad de Maceió, Alagoas, Brasil, con base en los criterios de espacialización y conservación. El barrio Pajuçara fue tomado como objeto de estudio porque presenta variadas formas de ocupación del suelo. El método consistió en el análisis cartográfico y visitas in situ con el fin de verificar el estado de conservación de áreas verdes y vegetación. Los resultados mostraron una distribución desigual de las áreas verdes, cuya concentración está ligada a la puesta en valor del paseo marítimo y su entorno con edificios y hoteles de alta gama, en contraste con la fracción interna del barrio, ocupada por una población de menor poder económico, donde las áreas verdes son inexistentes.Green areas were analyzed in a tourist district in the city of Maceió, Alagoas, Brazil, based on the criteria of spatialization and conservation. Pajuçara was taken as an object of study because it presents different forms of land occupation, despite its reduced territorial dimension. The method consisted of cartographic analysis of existing green areas and on-site visits in order to verify the conservation status of green areas and vegetation. The results showed an uneven distribution of green areas, whose concentration is linked to the enhancement of the tourist seafront and its surroundings with high-end buildings and hotels, in contrast to the internal fraction of the neighborhood, occupied by a population with less economic power, where the areas green is nonexistent.Objetivou analisar áreas verdes em bairro turístico na cidade de Maceió, Alagoas, a partir dos critérios de espacialização e conservação destes espaços. Tomou-se o bairro Pajuçara como objeto de estudo por apresentar formas de ocupação do solo variada, apesar da sua reduzida dimensão territorial. O método consistiu na análise cartográfica das áreas verdes existentes e visitas in loco com vistas a verificar o estado de conservação das áreas verdes e da vegetação. Os resultados apontaram distribuição desigual das áreas verdes, cuja concentração está vinculada à valorização da orla marítima turística e seu entorno com edifícios de alto padrão e hotéis, contrariamente à fração interna do bairro, ocupada por população de menor poder econômico, onde as áreas verdes são inexistentes

A alfabetização midiática de jovens no combate às fake news : um série de podcasts contra a desinformação

Trabalho de Conclusão de Curso (graduação)—Universidade de Brasília, Faculdade de Comunicação, Departamento de Jornalismo, 2019.O presente trabalho busca promover a alfabetização midiática de jovens, por meio de uma série de podcasts, sobre fake news, explorando a variedade das formas que essas informações podem ser encontradas, quais são as implicações jurídicas em divulgá-las e qual a relação do jornalismo com o fenômeno. Os estudos abordam o contexto da alfabetização midiática de jovens e objetivou a realização de série de podcasts sobre fake news por meio dos conceitos do jornalismo, como valornotícia, além de analisar aspectos jurídicos e comunicacionais do fenômeno

Supercapacitor in battery charges of photovoltaic panel: analysis of the technical feasibility

The power generation from photovoltaic sources is variable and may contain unhoped fluctuations, which can be relieved by using energy storage systems. However, there is a technical contradiction in extracting the maximum power from a photovoltaic panel and the charge cycle of a battery. To overcome this problem, this paper presents an improvement consisting in a collaborative association of lithium ion batteries and supercapacitors showing the technical feasibility in a photovoltaic system. The structure of the energy conversion system was developed and was set up the converter’s configuration, design and operation simulation. The power management of full system implementation was simulated and the results are presented. The proposed system development and it technical analysis was carried out for both situations, with and without the use of supercapacitor. It was concluded that the supercapacitor in the photovoltaic systems bring better charging conditions, resulting in shorter charging times and better system performances.info:eu-repo/semantics/publishedVersio

Influence of brushing with natural dentifrices on color change : in vitro study

To evaluate in vitro the influence of daily brushing with the use of natural toothpastes on the color change of enamel in bovine teeth. Four dentifrices were used, one conventional Colgate Total 12 - Clean Mint (G1), and three natural, Contented Toothp

O Teorema de Robinson e a construção de campos eletromagnéticos nulos

Dissertação (mestrado)—Universidade de Brasília, Instituto de Ciências Exatas, Departamento de Matemática, 2014.O tema desta dissertação é o Teorema de Robinson, que trata da relação entre os chamados campos eletromagnéticos nulos e as congruências de geodésicas nulas shear-free no espaço de Minkowski. Atualmente, muito tem sido feito nos estudos de propriedades topológicas de campos eletromagnéticos nulos, como feito por W. Irvine em 2008 e H. Kedia 2013. Além disso, Adamo e Newman, em 2009, utilizaram as congruências de geodésicas nulas shear-free para o estudo e interpretação de problemas relacionados com a relatividade geral. Estes estudos são baseados no Teorema de Robinson, que relaciona toda congruência de geodésicas nulas shear-free com uma família de campos eletromagnéticos nulos e, reciprocamente, todo campo eletromagnético nulo com uma congruência nula de geodésicas shear-free, e o Teorema de Kerr, que caracteriza toda congruência de geodésicas nulas como os zeros de uma função analítica arbitrária. _______________________________________________________________________________ ABSTRACTThe theme of this work is the relation between null electromagnetic fields and congruence of null geodesic shear-free in Minkowski space-time, known as the Robinson Theorem. Recently studies have been done about topologic properties of null electromagnetic fields, such as W. Irvine in 2008 and H. Kedia 2013. Also, Adamo and Newman, in 2009, used the congruence of null geodesic shear-free to study and understand problems related to General Relativity. These studies are based in Robinson’s Theorem, which states that each congruence of null geodesic shear-free is related to a family of null electromagnetic fields and, conversely, each null electromagnetic field is related to a congruence of null geodesic shear-free, and Kerr’s Theorem, which relates a congruence of null geodesic shear-free to the zeros of an arbitrary analytic function