A multiwavelength study of near- and mid-infrared selected galaxies at high redshift: ERGs, AGN-identification and the contribution from dust

The main focus of this thesis is the IR spectral regime, which since the 70's and 80's has revolutionised our understanding of the Universe. A multi-wavelength analysis on Extremely Red Galaxy populations is first presented in one of the most intensively observed patch of the sky, the Chandra Deep Field South. By adopting a purely statistical methodology, we consider all the photometric and spectroscopic information available on large samples of Extremely Red Objects (EROs, 553 sources), IRAC EROs (IEROs, 259 sources), and Distant Red Galaxies (DRGs, 289 sources). We derive general properties: redshift distributions, AGN host fraction, star-formation rate densities, dust content, morphology, mass functions and mass densities. The results point to the fact that EROs, IEROs, and DRGs all belong to the same population, yet seen at different phases of galaxy evolution. The second part of this thesis is dedicated to the AGN selection in the IR, with particular relevance to the James Webb Space Telescope, to be launched in 2018. We develop an improved IR criterion (using K and IRAC bands) as an alternative to existing IR AGN criteria for the z<2.5 regime, and develop another IR criterion which reliably selects AGN hosts at 0<z<7 (using K, Spitzer-IRAC, and Spitzer-MIPS24um bands, KIM). The ability to track AGN activity since the end of reionization holds great advantages for the study of galaxy evolution. The thesis then focus on the importance of dust. Based on deep IR data on the Cosmological Survey, we derive rest-frame 1.6, 3.3, and 6.2um luminosity functions and their dependency on redshift. We estimate the dust contribution to those wavelengths and show that the hot dust luminosity density evolves since z=1-2 with a much steeper drop than the star-formation history of the Universe. Future prospects are finally discussed in the last chapter.Comment: PhD thesis at Lisbon University (Portugal); supervised by Dr. Jose Afonso, Dr. Bahram Mobasher; some corrections after the defence on 21st July; five chapters (4.5MB total, versionZero/highResolutionChap1/tableContents at: http://www.oal.ul.pt/~hmessias/hmessiasPhD2011v0.pdf .../hmessiasPhD2011.pdf .../hmessiasPhD2011tc.pdf); comments are welcomed ([email protected]

Da Personalidade Ao Trabalho: Um Estudo Sobre O Ambiente Laborativo Dos Refugiados No Brasil E A Efetividade Das Normas

Os Direitos da personalidade tutelam a integridade corporal e imaterial da pessoa humana. Esses são valores gerais aplicáveis a todas as relações jurídicas, inclusive, no meio ambiente do trabalho, que é o espaço onde a pessoa exerce cotidianamente as suas atividades e seus valores personalíssimos devem ser protegidos. Por conta de perseguições decorrentes de raça, religião, nacionalidade, relações com grupos e opinião política, pessoas migram para outros Estados e são considerados como refugiados, sendo tutelados pelo sistema universal e regional americano. Para que de fato os seus direitos da personalidade sejam respeitados no meio ambiente de trabalho é necessária a efetividade de normas e, portanto, que estas promovam políticas públicas de inclusão. Assim,  após o estudo ter se valido do procedimento metodológico dedutivo, bibliográfico e documental de pesquisa, com recorte em dados estatísticos, concluiu-se que as normas do Brasil ajustam-se formalmente aos aludidos preceitos internacionais, e que, porém, no plano interno possuem relativa efetividade e as políticas derivadas destas ainda são insuficientes

Imidazolium and picolinium-based electrolytes for electrochemical reduction of CO2 at high pressure

ABSTRACT: Ionic liquids (ILs) have been considered among one of the most promising materials under investigation for integration of CO2 capture and electrochemical reduction (ECR). In the design of an IL-based electrolyte that can be employed industrially, the understanding of the influence of IL structure on ECR was considered essential. In this context, electrolytes with trifluoromethanosulfonate (OTf) anion were investigated as aqueous electrolytes for electrochemical reduction of CO2 at high pressure and near room temperature with zinc electrodes. The effect of replacing the 1-ethyl-3-methyl-imidazolium cation [EMIM] by 1-ethyl-3-picolinium [C2(3)pic] and by 1-ethyl-4-picolinium [C2(4)pic] cations was studied. The use of picolinium-based electrolytes in ECR is for the first time reported. A high-pressure single compartment test bed was used for electrolyte screening. Carbon monoxide productivities and selectivities were determined for the several electrolytes with different water contents. The electrolytes were characterized by cyclic voltammetry and electrochemical impedance spectroscopy. Electrolyte conductivities and diffusion coefficients were estimated. The effect of the cations is complex as it affects conductivity, double layer structure, reaction reversibility and even the ionic liquid physical state. Notwithstanding, it is possible to tune these properties to achieve similar CO productions with reduced IL amounts, considering the nature of the cation and the water content, leading to the design of more cost effective electrolytes for efficient ECR process.info:eu-repo/semantics/publishedVersio

Caracterización De Los Modelos De Negocios Bajo La Lógica De La Economía De Los Costos De Transacción

Objective of the study: The main objective of this study is to characterize business models under the logic of governance structures discussed as viewed in Transaction Cost Economics (TCE).   Method: We identified the main elements that make up a business model on the literature. The models were combined in a graphic model with the main characteristics of the Transaction Cost Economics (TCE).   Originality / Relevance:  We have identified how the elements of a business model interact with each other from the perspective of TCE.   Main results: The results present the relationships among the components of a business model and the main conceptual characteristics of TCE. A business model is supported by elements such as asset specificities, frequencies and uncertainties, differentiation strategies, and others, all defined from customer segmentation.   Theoretical / methodological contributions: The main contributions are related to the advancement of literature on models and business, regarding its different elements, in the light of TCE. Thus, we hope to contribute with the characterization of competitiveness in different organizations which use different strategies.   Social / management contributions: Different kinds of organizations that already focus on the reduction of transactional costs can use the elements that characterize a business model in order to become more competitive.Objetivo (obrigatório): O presente estudo tem por objetivo caracterizar os modelos de negócios sob a lógica das estruturas de governança discutidas na Economia dos Custos de Transação (ECT).   Método (obrigatório): A partir da revisão na literatura, foram identificados os principais elementos que compõem um modelo de negócios, que foram então combinados em um modelo gráfico com as principais características da Economia dos Custos de Transação (ECT) adotadas.   Originalidade/Relevância (obrigatório): Com base na fundamentação teórica sobre o assunto, foi identificada a forma com que os elementos de um modelo de negócios interagem entre si, sob a lógica da ECT. Resultados (obrigatório): Os resultados apresentam as relações entre os componentes de um modelo de negócio e as principais características conceituais da ECT. Um modelo de negócio é suportado por elementos como as especificidades dos ativos, frequências e incertezas, estratégias de diferenciação, entre outros, definidos a partir da segmentação de clientes.   Contribuições teóricas/metodológicas (obrigatório): As principais contribuições estão relacionadas à complementaridade da literatura sobre modelos e negócios, em seus diferentes elementos, à luz da ECT de modo a caracterizar a competitividade de diferentes organizações, a partir de diferentes estratégias adotadas. Contribuições sociais / para a gestão (opcional): Diferentes organizações, que já se pautam na redução dos custos transacionais, podem se utilizar dos elementos que caracterizam um modelo de negócio para se tornarem mais competitivas.   Palavras-chave: Competitividade Organizacional; Estratégia; Estrutura de Governança.Objetivo: El presente estudio tiene como objetivo caracterizar los modelos de negocios bajo la lógica de las estructuras de gobernanza discutidas por la Economía de los Costos de Transacción (ECT).   Método: A partir de la revisión en la literatura, se identificaron los principales elementos que componen un modelo de negocio, que luego se combinaron con un modelo gráfico a las principales características de la Economía de los Costos de Transacción (ECT) adoptadas.   Originalidad / Relevancia: Con base en la fundamentación teórica sobre el asunto, se identificó la forma en que los elementos de un modelo de negocio se interrelacionan entre sí bajo la lógica de la ECT.   Resultados: Los resultados presentan las relaciones entre los componentes de un modelo de negocio y las principales características conceptuales de la ECT. Un modelo de negocio es soportado por elementos como las especificidades de los activos, frecuencias e incertidumbres, estrategias de diferenciación, entre otros definidos a partir de la segmentación de clientes.   Contribuciones teóricas / metodológicas: Las principales contribuciones están relacionadas con la complementariedad de la literatura sobre modelos y negocios, en sus diferentes elementos, a la luz de la ECT para caracterizar la competitividad de diferentes organizaciones a partir de diferentes estrategias adoptadas.   Contribuciones sociales / para la gestión: Diferentes organizaciones que ya se basan en la reducción de los costos transaccionales, pueden utilizarse en los elementos que caracterizan un modelo de negocio para llegar a ser más competitivos.   Palabras clave: Competitividad Organizacional; Estrategia, Estructura de Gobernanza

Rest-Frame UV-Optical Selected Galaxies at 2.3 ≾ z ≾ 3.5: Searching for Dusty Star-forming and Passively Evolving Galaxies

A new set of color selection criteria (VJL) analogous with the BzK method is designed to select both star-forming galaxies (SFGs) and passively evolving galaxies (PEGs) at 2.3 ≾ z ≾ 3.5 by using rest-frame UV-optical (V – J versus J – L) colors. The criteria are thoroughly tested with theoretical stellar population synthesis models and real galaxies with spectroscopic redshifts to evaluate their efficiency and contamination. We apply the well-tested VJL criteria to the HST/WFC3 Early Release Science field and study the physical properties of selected galaxies. The redshift distribution of selected SFGs peaks at z ~ 2.7, slightly lower than that of Lyman break galaxies at z ~ 3. Comparing the observed mid-infrared fluxes of selected galaxies with the prediction of pure stellar emission, we find that our VJL method is effective at selecting massive dusty SFGs that are missed by the Lyman break technique. About half of the star formation in massive (M_(star) > 10^(10) M_☉) galaxies at 2.3 ≾ z ≾ 3.5 is contributed by dusty (extinction E(B – V) > 0.4) SFGs, which, however, only account for ~20% of the number density of massive SFGs. We also use the mid-infrared fluxes to clean our PEG sample and find that galaxy size can be used as a secondary criterion to effectively eliminate the contamination of dusty SFGs. The redshift distribution of the cleaned PEG sample peaks at z ~ 2.5. We find six PEG candidates at z > 3 and discuss possible methods to distinguish them from dusty contamination. We conclude that at least part of our candidates are real PEGs at z ~ 3, implying that these types of galaxies began to form their stars at z ≳ 5. We measure the integrated stellar mass density (ISMD) of PEGs at z ~ 2.5 and set constraints on it at z > 3. We find that the ISMD grows by at least about a factor of 10 in 1 Gyr at 3 < z <5 and by another factor of 10 in the next 3.5 Gyr (1 < z < 3)

SOFIA/HAWC+ Detection of a Gravitationally Lensed Starburst Galaxy at z = 1.03

We present the detection at 89 μm (observed frame) of the Herschel-selected gravitationally lensed starburst galaxy HATLAS J1429-0028 (also known as G15v2.19) in 15 minutes with the High-resolution Airborne Wideband Camera-plus (HAWC+) onboard the Stratospheric Observatory for Infrared Astronomy (SOFIA). The spectacular lensing system consists of an edge-on foreground disk galaxy at z = 0.22 and a nearly complete Einstein ring of an intrinsic ultra-luminous infrared (IR) galaxy at z = 1.03. Is this high IR luminosity powered by pure star formation (SF) or also an active galactic nucleus (AGN)? Previous nebular line diagnostics indicate that it is star formation dominated. We perform a 27-band multiwavelength spectral energy distribution (SED) modeling including the new SOFIA/HAWC+ data to constrain the fractional AGN contribution to the total IR luminosity. The AGN fraction in the IR turns out to be negligible. In addition, J1429-0028 serves as a testbed for comparing SED results from different models/templates and SED codes (magphys, sed3fit, and cigale). We stress that star formation history is the dominant source of uncertainty in the derived stellar mass (as high as a factor of ~10) even in the case of extensive photometric coverage. Furthermore, the detection of a source at z ~ 1 with SOFIA/HAWC+ demonstrates the potential of utilizing this facility for distant galaxy studies including the decomposition of SF/AGN components, which cannot be accomplished with other current facilities