Copper and Barium Abundances in the Ursa Major Moving Group

We present Cu and Ba abundances for 7 G-K dwarf stars, members of the solar-metallicity, 0.3 Gyr old Ursa Major Moving Group. All analyzed member stars show [Ba/Fe] excesses of +0.3-plus, associated with [Cu/Fe] deficiencies of up to -0.23 dex. The present results suggest that there is an anti-correlation between the abundances of Cu and the heavy elements produced by the main component of the neutron capture s-process. Other possible anomalies are Na and C deficiencies with respect to normal solar-metallicity stars. The new data do not confirm the recent claim that the group member HR6094 is a Ba dwarf star.Comment: 8 pages, 6 figures, accepted to MNRA

A photometric and spectroscopic survey of solar twin stars within 50 parsecs of the Sun: I. Atmospheric parameters and color similarity to the Sun

Solar twins and analogs are fundamental in the characterization of the Sun's place in the context of stellar measurements, as they are in understanding how typical the solar properties are in its neighborhood. They are also important for representing sunlight observable in the night sky for diverse photometric and spectroscopic tasks, besides being natural candidates for harboring planetary systems similar to ours and possibly even life-bearing environments. We report a photometric and spectroscopic survey of solar twin stars within 50 pc of the Sun. Hipparcos absolute magnitudes and (B-V)_Tycho colors were used to define a 2 sigma box around the solar values, where 133 stars were considered. Additional stars resembling the solar UBV colors in a broad sense, plus stars present in the lists of Hardorp, were also selected. All objects were ranked by a color-similarity index with respect to the Sun, defined by uvby and BV photometry. Moderately high-resolution, high-S/N spectra were used for a subsample of equatorial-southern stars to derive Teff, log g, and [Fe/H] with average internal errors better than 50 K, 0.20 dex, and 0.08 dex, respectively. Ages and masses were estimated from theoretical HR diagrams. The color-similarity index proved very successful. We identify and rank new excellent solar analogs, which are fit to represent the Sun in the night sky. Some of them are faint enough to be of interest for moderately large telescopes. We also identify two stars with near-UV spectra indistinguishable from the Sun's. We present five new "probable" solar twin stars, besides five new "possible" twins. Masses and ages for the best solar twin candidates lie very close to the solar values, but chromospheric activity levels range somewhat. We propose that the solar twins be emphasized in the ongoing searches for extra-solar planets and SETI searches.Comment: 25 pages, 15 figures, 14 table

Graded identities of block-triangular matrices

Let $F$ be an infinite field and $UT(d_1,\dots, d_n)$ be the algebra of upper block-triangular matrices over $F$. In this paper we describe a basis for the $G$-graded polynomial identities of $UT(d_1,\dots, d_n)$, with an elementary grading induced by an $n$-tuple of elements of a group $G$ such that the neutral component corresponds to the diagonal of $UT(d_1,\dots,d_n)$. In particular, we prove that the monomial identities of such algebra follow from the ones of degree up to $2n-1$. Our results generalize for infinite fields of arbitrary characteristic, previous results in the literature which were obtained for fields of characteristic zero and for particular $G$-gradings. In the characteristic zero case we also generalize results for the algebra $UT(d_1,\dots, d_n)\otimes C$ with a tensor product grading, where $C$ is a color commutative algebra generating the variety of all color commutative algebras.Comment: 24 pages and 39 references. We have added section 5 in the text about tensor products by color commutative superalgebra

Campaign Advertising and Election Outcomes: Quasi-Natural Experiment Evidence from Gubernatorial Elections in Brazil

Whether campaign advertising influences election outcomes is an open question; a paradox given the amount spent on campaigning in general and TV advertising in particular. We argue that such “absence of documentation” is due to the focus of the empirical literature on the United States, in which the allocation of campaign spending and advertising is decentralized. We explore a quasinatural experiment that enables us to mitigate the omitted variables and reverse causality problems caused by decentralized allocation. In Brazil, gubernatorial elections work in a two-round system. In the first round, candidates’ TV time shares are determined by their coalitions’ share of seats in the National Parliament. In the second round, TV time is split equally between the first-round winner and runner-up. Using differences between rounds as a source of variation, we find a large causal effect of TV advertising on election outcomes.TV Advertising; Campaign Spending; Election Outcomes; Endogeneity; Quasi-Natural Experiments

Phase Separation and the Dual Nature of the Electronic Structure in Cuprates

The dual nature of the electronic structure of stripes in $La_{2-x}Sr_xCuO_4$ was characterized by experimental observations, mainly by ARPES, of nodal spectral weight together with the straight segments near antinodal regions. We present here an attempt to understand this dual behavior in terms of the competition of order and disorder, by applying the phase separation theory of Cahn-Hilliard (CH) to the high pseudogap temperature, which is very large in the far underdoping region and vanishs near the doping level p=0.2. The spinodal phase separation predictions together with the Bogoliubov-deGennes (BdG) superconducting theory provides several interesting insights. For instance, we find that the disorder enhances the local superconducting gap which scales with the leading edge shift and that, upon doping, the size of the hole-rich stripes increases, yielding to the system their metallic properties.Comment: revised version, 4 pages and 3 fig

Desigualdades sociais e acesso seletivo ao ensino superior no Brasil no período 1994-2001

O ensino superior no Brasil experimentou um significativo processo de expansão, iniciado em meados da década de 90. A retomada do crescimento do número de matrículas, após um período de estagnação na década anterior, ocorreu num contexto de aumento do número de concluintes do nível médio, e acentuou-se a partir de 1997, sob os efeitos das políticas governamentais para a ampliação da oferta de vagas. O setor privado foi o principal responsável pelo processo de expansão, em vista da redução das restrições legais para a criação de novos cursos e instituições. Este trabalho investiga as relações entre as chances de ingresso e o risco de evasão e algumas características sociais e familiares dos estudantes, no contexto da expansão recente deste nível de ensino no Brasil. A análise foi baseada nos dados da Pesquisa Mensal do Emprego do IBGE de 1994 a 2001. Os resultados indicam que tanto o ingresso quanto a evasão são fortemente condicionados pelas características sociais dos estudantes, que as chances de ingresso reduziram-se para o conjunto dos concluintes do ensino médio e que o risco de evasão manteve-se constante. Também não foram observadas alterações nas desigualdades de acesso entre estudantes de diferentes grupos sociais no período

Desenvolvimento e aplicação biológica de nanossistemas contendo novos fotossensibilizantes derivados do benzo[a]fenoxazinio

Dissertação (mestrado)—Fundação Universidade de Brasília, Programa de Pós-Graduação em Biologia Animal, 2019.O presente trabalho teve como proposta desenvolver dois nanosistemas contendo fotossensibilizantes (FS) sintéticos do tipo benzo[a]fenoxazínio para serem utilizados em terapia fotodinâmica. Foram desenvolvidos um lipossoma e um nanocarreador lipídico nanoestruturado. Em seguida, foram associados a eles diferentes fotossensibilizantes conjugados com moléculas biológicas para direcionamento do fotossensibilizante ao tumor. O presente trabalho apresenta o desenvolvimento de nanossistemas de fabricação simples, com componentes já estabelecidos como pouco tóxicos, permitindo assim maior facilidade de produção e aplicabilidade na TFD. O trabalho analisou a atividade biológica dos sistemas desenvolvidos em diferentes tipos de linhagens celulares. Os lipossomas foram desenvolvidos pela técnica de hidratação de filme lipídico e os nanocarreadores lipídicos nanoestruturados pelo método de temperatura de inversão de fases. Os ensaios biológicos, in vitro, foram feitos pelo método 3,(4,5- dimethylthiazol- 2-yl)-2,5-diphenyltetrazolium bromide (MTT). Ao avaliar os nanosistemas desenvolvidos como possíveis fotossensibilizantes, notou-se que eles apresentaram boas características para ser utilizados em TFD. Possuem características fotofísicas que o habilitam como FS, além de apresentar capacidade de gerar ERO, baixa toxicidade no escuro e capacidade de reduzir a viabilidade de células tumorais in vitro, quando irradiado.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) e Fundação de Apoio à Pesquisa do Distrito Federal (FAP/DF).The present work had as proposal to develop two nanosystems containing synthetic benzo [a] phenoxazinium photosensitizers (FS) to be used in photodynamic therapy. A liposome and a nanostructured lipid nanocarrier have been developed. Subsequently, different photosensitizers conjugated with biological molecules were associated with them to direct the photosensitizer to the tumor. The present work presents the development of simple manufacturing nanosystems, with components already established as little toxic, thus allowing greater ease of production and applicability in PDT. The work analyzed the biological activity of the systems developed in different types of cell lines. Liposomes were developed by the lipid film hydration technique and nanostructured lipid nanocarriers by the phase inversion temperature method. Biological assays, in vitro, were done by the method 3, (4,5-dimethylthiazol-2-yl) -2,5-diphenyltetrazolium bromide (MTT). When evaluating the nanosystems developed as possible photosensitizers, it was observed that they presented good characteristics to be used in PDT. They have photophysical characteristics that enable it as FS, besides being able to generate ERO, low toxicity in the dark and ability to reduce the viability of tumor cells in vitro, when irradiated

Dispositivos de seguridad pública y procesos de urbanización en favelas de Rio de Janeiro: nuevos conflictos en el espacio urbano

A partir del trabajo de campo realizado en la favela Santa Marta, buscaremos aquí evidenciar la dimensión de los conflictos generados por los procesos de regularización urbanística y por la substitución gradual de prácticas “informales” de acceso a los servicios, desde la implementación de las Unidades de Policía Pacificadora (UPPs). Buscaremos, del mismo modo, llamar la atención sobre las implicaciones de tales acciones sobre el proceso de formalización y reconocimiento de una dirección en la ciudad. Se pretende, desde esta perspectiva, asociar la dimensión de las identidades y de las representaciones sociales con el proceso más amplio de reestructuración urbana en curso en la ciudad de Rio de Janeiro, buscando discutir los efectos de las políticas de Seguridad Pública, implementadas en distintas favelas, sobre la vida cotidiana de sus habitantes en el contexto de importantes eventos internacionales, como la Copa Mundial de Fútbol de 2014 y los Juegos Olímpicos de 2016. Palabras claves: favelas; seguridad pública; conflictos; procesos de urbanización; Rio de Janeiro. Abstract Based on field research carried out in the Santa Marta favela (slum) of Rio de Janeiro, this article focuses on the conflicts generated by urban regulation as well as the gradual substitution of “informal” ways of accessing public services. It also shows the implications of such actions for the formalization and recognition of an address in the city. From this perspective it is argued that identities and social representations are connected to a broader process of urban restructuring taking place in Rio de Janeiro. The analysis focuses on public policies regarding security implemented in different favelas and their effects on the everyday lives of their inhabitants in the context of important international events such as the 2014 World Cup and the Olympic Games of 2016. Key words: favelas; public security; conflict; urbanization; Rio de Janeiro

Spin-1 Particles with Light-Front Approach

For the vector sector, i.e, mesons with spin-1, the electromagnetic form factors and anothers observables are calculated with the light-front approach. However, the light-front quantum field theory have some problems, for example, the rotational symmetry breaking. We solve that problem added the zero modes contribuition to the matrix elements of the electromagnetic current, besides the valence contribuition. We found that among the four independent matrix elements of the plus component in the light-front helicity basis only the $0\to 0$ one carries zero mode contributions.Comment: 5 pages. 3 Figures, use latex and EPJ styl