Kinetic Monte Carlo simulation of the nitridation of the GaAs (100) surfaces

We present, in this work, our preliminary results of a systematic theoretical study of the adsorption of N over As-terminated GaAs (100) (2$\times$1) surfaces. We analyzed the changes in the bond-lenghts, bond-angles and the energetics involved before and after deposition. Our results show that the N-atoms will prefer the unoccupied sites of the surface, close to the As dimer. The presence of the N pushes the As dimer out of the surface, leading to the anion exchange between the N and As atoms. Based on our results, we discussed about the kinetics of the N islands formation during epitaxial growth of the III-Nitrides.Comment: 4 pages, 7 figures, accepted for publication in Braz. J. Phys., special number, Proceedings of BWSP-12, 12th Brazilian Workshop on Semiconductor Physic

Ab initio calculation of the dynamical properties of PPP and PPV

In this work, we have calculated the vibrational modes and frequencies of the crystalline PPP (in both the Pbam and Pnnm symmetries) and PPV (in the P21/c symmetry). Our results are in good agreement with the available experimental data. Also, we have calculated the temperature dependence of their specific heats at constant volume, and of their vibrational entropies. Based on our results, at high temperatures, the PPP is more stable in the Pnnm structure than in the Pbam one.Comment: 5 pages, 7 figures, accepted for publication in Braz. J. Phys., special number, Proceedings of BWSP-12, 12th Brazilian Workshop on Semiconductor Physic

Cross-border acqusitions and firm internationalisation : the case of Sogrape and Cotesi

In a globalised world like today, new challenges are imposed on national companies and products. Internationalisation emerges as an imperative for the survival of organizations. There is rich literature in the field of the cross-border acquisitions. However, it is focused on its pre- and post-acquisition process, taking a financial, accounting and human resource’s perspectives. There is a gap in the study of cross-border acquisitions in an international business perspective. Therefore, this multiple case study research will analyse the effect of cross-border acquisitions in the firm internationalisation of two Portuguese multinational firms, which have several years of existence. In this way, the aim of this study is to realise how did these companies grew in the international arena through cycles of cross-border acquisitions, their organisational background, strategies adopted to the expansion of the brand and product to foreign markets and what was the role of the business networks. In the end, it is possible to understand the effect of cross-border acquisitions in their internationalisation process and how did they strengthened their positions within their business networks, becoming world leading companies

Competitive advantage in the age of digital platforms : the case of Amazon.com

No mundo cada vez mais digital, interconectado e dinâmico em que vivemos hoje, a única constante é a mudança. A economia digital mudou significativamente a forma como as empresas competem, operam e colaboram. As teorias tradicionais de vantagem competitiva, como as Cinco Forças de Porter, estratégias genéricas e a visão baseada em Recursos de Barney, são baseadas numa conceção de um mundo que é essencialmente estático. Indústrias claramente definidas, criação de barreiras para proteger as empresas face à concorrência, pureza estratégica, recursos específicos da empresa que são valiosos, raros e difíceis de imitar pelos concorrentes e até mesmo a sustentabilidade da vantagem competitiva são questionadas num mundo de plataformas digitais. Embora haja uma vasta e rica literatura sobre vantagem competitiva, a literatura relativa à economia digital e às plataformas digitais ainda está a emergir. Deste modo, este estudo visa responder a duas questões de investigação, nomeadamente: (1) Como é que a economia digital mudou a vantagem competitiva? (2) Como é que a vantagem competitiva é alcançada na era das plataformas digitais? Para este propósito, foi realizado um caso de estudo sobre a Amazon.com recorrendo apenas a dados secundários para entender como este gigante digital construiu o seu caminho na economia digital, crescendo exponencialmente tanto em escala como em âmbito e tornando-se na empresa mais valiosa do mundo em 2019. Esta dissertação conclui que o que se acredita como verdadeiro sobre a vantagem competitiva, resultante dos modelos tradicionais de estratégia, necessita de ser alterado para incluir novos conceitos à luz da economia digital e das plataformas digitais. Teorias que valorizavam indústrias definidas, posicionamento estratégico para evitar a concorrência, construção de barreiras para proteger os negócios, preservação dos recursos distintos dentro dos limites da empresa deram lugar a indústrias indefinidas, network effects, foco no consumidor, ecossistemas e inovação. O poder da economia digital está ainda a ser revelado; isto é apenas o começo da revolução das plataformas digitais.In the increasingly digital, interconnected and dynamic world that we live in today, the only constant is change. The digital economy shaped the competitive landscape, changing the way businesses compete, operate and collaborate. Traditional theories of competitive advantage, such as Porter’s Five Forces, generic strategies and Barney’s Resource-based view, are rooted in a conception of the world that is essentially static. Clearly defined industries, barriers that protect businesses from competitors, strategic purity, and firm-specific resources that are valuable, rare and difficult for competitors to imitate and even the sustainability of competitive advantage are questioned in a world of digital platforms. Although there is a vast and rich literature on competitive advantage, research on the digital economy and digital platforms is still emerging. Therefore, this study aims to answer two research questions: (1) How did the digital economy change competitive advantage? (2) How is competitive advantage achieved in the age of digital platforms? For this purpose, a case study on Amazon.com was conducted relying only on secondary data to understand how this digital giant built its path on the digital economy, growing exponentially in scale and scope and becoming the most valuable company in the world in 2019. This research concludes that once taken-for-granted assumptions on competitive advantage may need to change to include new concepts in light of the digital economy and digital platforms. Theories that valued defined industries, avoidance of competition, building moats to protect businesses, keeping distinctive resources inside the boundaries of the firm have given place to blurred industry boundaries, network effects, customer centricity, ecosystems and innovation. The power of the digital economy is just starting to reveal itself; this is only the beginning of the platform revolution

Fisher matrix forecasts for astrophysical tests of the stability of the fine-structure constant

We use Fisher Matrix analysis techniques to forecast the cosmological impact of astrophysical tests of the stability of the fine-structure constant to be carried out by the forthcoming ESPRESSO spectrograph at the VLT (due for commissioning in late 2017), as well by the planned high-resolution spectrograph (currently in Phase A) for the European Extremely Large Telescope. Assuming a fiducial model without $\alpha$ variations, we show that ESPRESSO can improve current bounds on the E\"{o}tv\"{o}s parameter---which quantifies Weak Equivalence Principle violations---by up to two orders of magnitude, leading to stronger bounds than those expected from the ongoing tests with the MICROSCOPE satellite, while constraints from the E-ELT should be competitive with those of the proposed STEP satellite. Should an $\alpha$ variation be detected, these measurements will further constrain cosmological parameters, being particularly sensitive to the dynamics of dark energy.Comment: Phys. Lett. B (in press

Saúde ambiental

Este material compõe a disciplina optativa "Vigilância à saúde ambiental" do Curso de Especialização Estratégia Saúde da Família (2014). Esta disciplina tem o objetivo de provocar uma reflexão sobre a relação saúde e ambiente, contextualizando os principais cenários vivenciados na realidade brasileira e incorporando a atuação dos profissionais das equipes de Saúde da Família. São abordadas situações de risco ambiental provocado por ocupações populacionais inadequadas, exposiçoes a substâncias químicas, condições inadequadas de infraestrutura básica e demais situações de adversidades à saúde pública provocada pelo ambiente. Este módulo está dividido em 3 seções: Seção 1 - Conceitos e a evoluçãoda saúde ambiental; Seção 2 - A relação saúde e ambiente; Seção 3 - Questões de saúde ambiental para a equipe de saúde da famíliaBanco Nacional de Desenvolvimento Econômico e Social - BNDE

Quantification of LSD in illicit samples by high performance liquid chromatography

In the present study, a method using high performance liquid chromatography to quantify LSD, in blotter papers seized in Minas Gerais, was optimized and validated. Linearity, precision, recovery, limits of detection and quantification, and selectivity were the parameters used to evaluate performance. The samples were extracted with methanol:water (1: 1) in an ultra-sound bath. The linearity between 0.05 and 20.00 μg/mL (0.5 and 200.0μg of LSD/blotter) was observed with satisfactory mean intra and inter assay precision (RSDr = 4.4% and RSD R = 6.4%, respectively) and with mean recoveries of 83.4% and 84.9% to the levels of 1.00 and 20.00 μg/mL (10 and 200μg LSD/blotter). The limits of detection and quantification were 0.01 and 0.05 μg/mL, respectively (0.1 and 0.5 μg of LSD/blotter). The samples of blotters (n =22) were analyzed and the mean value of 67.55 μg of LSD/blotter (RSD=27.5%) was found. Thus, the method used showed satisfactory analytical performance, and proved suitable as an analytical tool for LSD determination in illicit samples seized by police forces.No presente trabalho, um método utilizando cromatografia líquida de alta eficiência foi otimizado e validado para quantificar o LSD em selos apreendidos em Minas Gerais. A linearidade, precisão, recuperação, limites de detecção e quantificação e seletividade foram os parâmetros de desempenho avaliados. As amostras foram extraídas com metanol: água (1:1) em banho de ultra-som. A linearidade entre 0,05 a 20,00 mg/mL (0,5 a 200 μg LSD/blotter) foi observada com precisão média, intra e inter ensaio, satisfatória (RSDr = 4,4% e RSD R = 6,4%, respectivamente) e com recuperações médias de 83,4% e 84,9% para os níveis de LSD de 1,00 e 20,00 mg/mL (10 e 200 μg LSD/selo). Os limites de detecção e quantificação encontrados foram de 0,01 e 0,05 mg/mL, respectivamente (0,1 e 0,5 μg LSD/selo). As amostras de selos (n = 22) foram analisadas e o valor médio encontrado foi de 67,55 μg de LSD/selo (RSD% = 27,5). Desta forma, o método analítico apresentou desempenho satisfatório, capaz de ser utilizado como instrumento de análise para a determinação do LSD em amostras ilícitas apreendidas pelas forças policiais

The impact of pay dispersion on organizational performance

Although there are many theories and several studies aiming to explain the impact of pay dispersion on firm performance, the existence and direction of this relationship, as well as what factors moderate it, remains unclear. Using the PRISMA methodology, the present study performed a systematic literature review and gathered a sample of 26 papers on the topic to understand how pay dispersion is defined and conceptualized, if a relationship between pay dispersion and firm performance exists and if the impact of the first on the latter is positive or negative, to gather and study the existing theories that connect pay dispersion and organizational performance and understand which ones explain the found impacts, to verify if there are any variables that moderate this relationship and, if so, which ones. The present study has found that although studies on vertical pay dispersion mainly find a positive impact, confirming tournament arguments, and studies on horizontal dispersion find a negative one, confirming equity/fairness arguments, the existence of a relationship, its direction and intensity seems to depend on several contextual factors, pointing towards a contingency perspective.Embora existam muitas teorias e vários estudos com o objetivo de explicar o impacto da dispersão salarial no desempenho organizacional, a existência e a direção dessa relação, bem como que fatores o moderam, permanecem incertas. Utilizando a metodologia PRISMA, o presente estudo executou uma revisão sistemática de literatura e reuniu uma amostra de 26 artigos sobre o tema de forma a compreender de que forma a dispersão salarial é definida e concetualizada, se existe uma relação entre a dispersão salarial e o desempenho da empresa e se o impacto da primeira no último é positivo ou negativo, reunir e estudar as teorias existentes que conectam a dispersão salarial e o desempenho organizacional e entender quais explicam os impactos encontrados, verificar se existem variáveis que moderem esse relacionamento e, em caso afirmativo, quais. Este estudo constatou que, embora os estudos sobre dispersão vertical de salários encontrem principalmente um impacto positivo, confirmando os argumentos da teoria dos torneios, e os estudos sobre dispersão horizontal encontrem um impacto negativo, confirmando argumentos de equidade/justiça, a existência de um relacionamento, a sua direção, e intensidade parecem depender de vários fatores contextuais, apontando para uma perspetiva de contingência