The Fate of Dwarf Galaxies in Clusters and the Origin of Intracluster Stars

This thesis presents a review of related important concepts in cosmology followed by details of the author's role in a research project on the origin of intracluster light. The author's role in the development of the simulations varied from searching parameters in the literature, through writing and modifying code in IDL, FORTRAN, and UNIX to carrying out hundreds of simulations using the particle-particle algorithm described in this thesis, as well as partaking in joint analysis of the simulation results. Part of this work in the isolated cluster simulations has been submitted for publication (Barai, Brito & Martel 2009). The main results of the simulations described in this thesis are: 1) destruction of dwarf galaxies by mergers dominates destruction by tides, and 2) destruction of galaxies by tides is sufficient to explain the observed intracluster light. These results support the accepted explanation for the origin of the intracluster light. In an ongoing, second stage of the simulation, which extends the isolated cluster results to a cosmologically significant region of the Universe, the author similarly assists in the implementation of a particle-particle/particle-mesh simulation and the joint analysis of the results to-date. The results are as per the Schechter luminosity function, and suggest the approach used is valid and the results obtained robust.Comment: Master's thesis, 78 page

The fate of dwarf galaxies in clusters and the origin of intracluster stars

Ce mémoire résume quelques concepts importants en cosmologie et présente l étude faite par l'auteur sur l'origine de la lumière intra-amas. Pour la réalisation de ce projet, l'auteur a tout d'abord recherché dans la littérature les paramètres à utiliser pour des simulations en langage FORTRAN dont les algorithmes de base sont, dans la première partie du projet, particule-particule et, dans la seconde, particule-particulejparticule-maille. L'auteur a également modifié des codes IDL et UNIX. Enfin, le projet nécessita des centaines de simulations d 'amas isolés dont les résultats ont été analysés en collaboration avec les membres du groupe de recherche et soumis pour publication (Barai, Brito & Martel 2009). Les résultats principaux des simulations décrites dans ce document sont: 1) la destruction des galaxies naines par des fusions domine sur la destruction par des marées, et 2) la destruction des galaxies par des marées est suffisante pour expliquer la lumière intra-amas observée. Finalement, les résultats d 'amas isolés ont été généralisés à une région significative de l'Univers. Ainsi, l'auteur a contribué à la mise en oeuvre d'une simulation particule-particulejparticule-maille et à l'analyse commune des résultats obtenus à ce jour. Les résultats reproduisent la fonction de luminosité de Schechter, et suggèrent que l'approche utilisée est valide et que les résultats sont robustes

The Fate of Dwarf Galaxies in Clusters and the Origin of Intracluster Stars. II. Cosmological Simulations

We combine a N-body simulation algorithm with a subgrid treatment of galaxy formation, mergers, and tidal destruction, and an observed conditional luminosity function Phi(L|M), to study the origin and evolution of galactic and extragalactic light inside a cosmological volume of size (100 Mpc)^3, in a concordance LCDM model. This algorithm simulates the growth of large-scale structures and the formation of clusters, the evolution of the galaxy population in clusters, the destruction of galaxies by mergers and tides, and the evolution of the intracluster light. We find that destruction of galaxies by mergers dominates over destruction by tides by about an order of magnitude at all redshifts. However, tidal destruction is sufficient to produce intracluster light fractions f_ICL that are sufficiently high to match observations. The bulk of the intracluster light (60%) is provided by intermediate galaxies of total masses 10^11 Msun-10^12 Msun and stellar masses 6x10^8 Msun-3x10^10 Msun that were tidally destroyed by even more massive galaxies. The contribution of low-mass galaxies to the intracluster light is small and the contribution of dwarf galaxies is negligible, even though, by numbers, most galaxies that are tidally destroyed are dwarfs. Tracking clusters back in time, we find that their values of f_ICL tend to increase over time, but can experience sudden changes that are sometimes non-monotonic. These changes occur during major mergers involving clusters of comparable masses but very different intracluster luminosities. Most of the tidal destruction events take place in the central regions of clusters. As a result, the intracluster light is more centrally concentrated than the galactic light. Our results support tidal destruction of intermediate-mass galaxies as a plausible scenario for the origin of the intracluster light.Comment: 13 figures, one in color. Accepted for publication in Ap

A comparison of small mammal communities in two High-Andean Polylepis woodlands in Ecuador

Polylepis forest, historically widespread throughout high elevations of the central and northern Andes, now remain only in discontinuous small patches.  An expanding agricultural frontier, along with other anthropogenic pressures, imperils these remnants through further isolation and loss of habitat quality. Using two grids of live traps we compared the populations of small nonvolant mammals in an intact Polylepis woodland with one nearby that had been logged 50 years before. Our study is the first to examine the effects of habitat degradation and associated changes to vertical complexity and habitat heterogeneity on mammalian communities in Polylepis woodlands above 3500 m. The intact woodland had significantly more vertical complexity than the mid-successional woodland.  A total of 315 captures of 147 individuals of 9 species were sampled during an intensive trapping effort in 2010.  Trap success was especially high averaging 35.4 % and 28.1 % in the intact and mid-successional woodland, respectively.  Diversity and abundance of small mammals were greater in the intact woodland than the mid-successional site.  Forest specialist species were more abundant in the intact habitat; while Thomasomys paramorum, a habitat generalist, was dominant in both.  Habitat quality affected movement patterns of T. paramorum.  The results affirm a high diversity and density of small mammals in intact Polylepis woodland and indicate that the effects of habitat disturbance are species dependent.  We suggest that habitat specialists are more susceptible to loss of habitat heterogeneity and vertical complexity than habitat generalists.&nbsp

Management of Root-knot Nematode (Meloidogyne incognita) onPittosporum tobira Under Greenhouse, Field, and On-farm Conditions in Florida

Root-knot nematodes are important pests of cut foliage crops in Florida. Currently, effective nematicides for control of these nematodes on cut foliage crops are lacking. Hence, research was conducted at the University of Florida to identify pesticides or biopesticides that could be used to manage these nematodes. The research comprised on-farm, field, and greenhouse trials. Nematicide treatments evaluated include commercial formulations of spirotetramat, furfural, and Purpureocillium lilacinum (=Paecilomyces lilacinus) strain 251. Treatment applications were made during the spring and fall seasons according to manufacturer's specifications. Efficacy was evaluated based on J2/100 cm3 of soil, J2/g of root, and crop yield (kg/plot). Unlike spirotetramat, which did not demonstrate any measurable effects on Meloidogyne incognita J2 in the soil, furfural and P. lilacinum were marginally effective in reducing the population density of M. incognita on Pittosporum tobira. However, nematode reduction did not affect yield significantly. Although furfural and P. lilacinum have some potential for management of M. incognita on cut foliage crops, their use as a lone management option would likely not provide the needed level of control. Early treatment application following infestation provided greater J2 suppression compared to late application,suggesting the need for growers to avoid infested fields

Efeito marginal da tributação direta sobre o lucro no Brasil : um estudo sobre os tributos diretos incidentes sobre as empresas dos setores não-financeiro

Trabalho de Conclusão de Curso (graduação)—Universidade de Brasília, Faculdade de Economia, Administração, Contabilidade e Gestão de Políticas Públicas, Departamento de Ciências Contábeis e Atuariais, 2019.Este artigo faz uma extensão à pesquisa de França, Filho e Sandoval (2019) e estuda a influência que o Ajuste Fiscal Líquido (AFL) exerce no Tributo Direto sobre o Lucro (TDL) através da geração de sinergia ou entropia de caixa. O TDL é obtido pela soma do Imposto de Renda da Pessoa Jurídica (IRPJ) e da Contribuição Social sobre o Lucro Líquido (CSLL), porém é necessário que sejam feitos ajustes sobre o Lucro Contábil (LC) para se chegar ao Lucro Tributável (LT) e encontrar o TDL, esses ajustes é o que chamamos de ajuste fiscal líquido. Foram feitas observações de 76 empresas listadas na Bovespa de diversos setores da economia brasileira, exceto o setor financeiro, no período de 2000 a 2017. Para as exigências dessa pesquisa, além do cálculo do AFL, é necessário estudar o Efeito Marginal da Tributação Direta Sobre o Lucro (EMgT). O EMgT é obtido através do sinal algébrico do AFL, que é a única variável necessária para observar a existência de sinergia/entropia de caixa nas companhias. Na pesquisa foi utilizada metodologia quantitativa com viés positivista. Os resultados encontrados indicaram que o AFL produz influência significativa no TDL e no EMgT, garantindo sinergia de caixa na maioria dos períodos observados, e a alíquota efetiva média se mostra menor do que a alíquota nominal de 34% sobre o lucro. Outro ponto que os resultados possibilitaram concluir é que a maioria das observações com entropia de caixa indicaram um Lucro Antes do Imposto de Renda (LAIR) negativo.This article extends the research of France, Filho and Sandoval (2019) and studies the influence that the Net Fiscal Adjustment (NFA) exerts on the Direct Tax on Profit (DTP) through the generation of synergy or entropy of cash. DTP is obtained by the sum of Corporate Income Tax (IRPJ, portuguese acronym) and Social Contribution on Net Income (CSLL, portuguese acronym), but it is necessary to make adjustments on the Accounting Profit (AP) to reach the Taxable Profit (TP) and find the DTP, these adjustments is what we call net tax adjustment. The observations were made from 76 companies listed on the Bovespa from various sectors of the Brazilian economy, except the financial sector, from 2000 to 2017. For the requirements of this research, besides the NFA calculation, it is necessary to study the Marginal Effect of Direct Taxation on o Profit (MgET). The MgET is obtained through the algebraic signal of the NFA, which is the only variable necessary to observe the existence of synergy / entropy of the box in the companies. In the research was used quantitative methodology with positivist bias. The results showed that NFA produces a significant influence on DTP and MgET, guaranteeing cash synergy in most of the observed periods, and the average effective rate is lower than the nominal rate of 34% on profit. Another point that the results allowed to conclude is that most of the observations with box entropy indicated a negative Profit Before Corporate Income Tax (PBCT)

Sensor de fluxo termico

Orientador: Rene RobertDissertação (mestrado) - Universidade Federal do ParanaResumo: Na ultima década, sensores de fluxo térmico tem sido utilizados nas mais diversas áreas e aplicações; da biologia a exploração da Lua, da industria têxtil aos hospitais. O protótipo de sensor de fluxo térmico descrito neste trabalho apresenta construção simples e baixo custo. O transdutor consiste em uma termopilha obtida pela eletrodeposição de cobre sobre um fio de constatam. Cada etapa da construção a calibração e descrita. Analisa-se a influencia que o sensor e suas características exercem sobre o processo de medida Também o funcionamento intrínseco de um termopar e analisado e as conclusões obtidas são verificadas experimentalmente através de medidas da forca termoeletromotriz em termopares de filma de cobre depositado sobre constatam. Conclui-se dessa analise que dois fatores que podem influenciar na performance do transdutor são a espessura e a rugosidade superficial da capa de cobre depositada. O equipamento pode medir fluxos de ate tres mil watts por metro quadrado com uma incerteza menor que seis por cento da medida, tempo de resposta inferior a vinte segundos e custo de material da ordem de quarenta dólares.Abstract: In the last ten years, heat flux meters had been used in many areas and applications; from Biology to lunar exploration, from textile factoiy to hospitals. This work describes a simple construction and low cost prototype. A thermopile, developed by electrochemical deposition of copper over a constantan wire, is used as transducer. Influences of the meter and its characteristics over measurement process are analyzed and verified through experimental measurements of thermoelectromotive force in copper film thermocouples. It is discussed how copper film thickness and superficial rugosity can affect transducer performance. The meter can measure up to three thousand watts per square meter within six percent uncertainty, twenty seconds response time and forty dollars material cost