13,235 research outputs found
Do Low Cost Carriers Have Different Corporate Governance Models?
In this paper, we investigate whether different business models in the same industry (passenger air transportation) lead to different corporate governance models. We found that low cost carriers (LCCs) organise their boards differently from full service carriers (FSCs), in order to achieve lower costs and the faster decision-making process that is required by their business model. We also found that LCCs and FSCs solve their potential agency cost problems differently. FSCs have more board committees in order to monitor management, and LCSs have a closer coincidence of interests between shareholders and management.corporate governance, low cost carriers
Does market concentration of downstream buyers squeeze upstream suppliersâ market power?
Using a theoretical model, we examine both the relationship between a downstream dominant firmâs market share and an upstream monopolyâs Lerner index and the relationship between upstream and downstream price elasticities of demand, in a regulated industry context. We undertake an empirical study that confirms our theoretical predictions, namely that the market share of a leader downstream firm is significant in explaining the upstream producersâ Lerner indexes. Also in accordance with the results of the theoretical model, the Lerner index is negatively influenced by the competition that suppliers face and by the level of economies of density, amongst other variables.vertical relations, buyersâ market power
Angola e China: numa encruzilhada?
Na continuação da nossa série de analises sobre o futuro das relaçÔes Sino-Africanas, Ana Cristina Alves da LSE e SAIIA , relata-nos o ponto da vista de Angola
Africa and China: At a crossroads in Angola
As we continue our series looking at the future of Sino-Africa relations, LSEâs Ana Cristina Alves gives us the view from Angola
Existence and concentration of ground state solutions for a critical nonlocal Schr\"odinger equation in
We study the following singularly perturbed nonlocal Schr\"{o}dinger equation
-\vr^2\Delta u +V(x)u =\vr^{\mu-2}\Big[\frac{1}{|x|^{\mu}}\ast F(u)\Big]f(u)
\quad \mbox{in} \quad \R^2, where is a continuous real function on
, is the primitive of , and \vr is a positive
parameter. Assuming that the nonlinearity has critical exponential
growth in the sense of Trudinger-Moser, we establish the existence and
concentration of solutions by variational methods.Comment: 3
IN-SITU XRD STUDIES OF THERMAL STABILITY OF PURE SILICA AND Ti-MCM-41 MATERIALS
In this work we present a study on the thermal stability of siliceous and titanium containing ordered mesoporous materials with MCM-41 structure, prepared by direct synthesis at ambient temperature and pressure, as previously described [1]. Grades with different pore diameter and Si/Ti molar ratios were analyzed, in the form of compacted powder, to assess its influence on the order-disorder transition temperature
Chinaâs oil diplomacy: comparing Chinese economic statecraft in Angola and Brazil
This thesis aims to investigate the reasons for the variation in Chinaâs oil diplomacy performance
in Africa and South America in the period 2000-2010. Lacking sound experience in pursuing oil
security overseas and enjoying strong financial muscle, Chinaâs oil diplomacy is largely rooted
in the extension of soft loans for infrastructure to oil-rich countries in exchange for steady oil
supply and favoured access to oil acreage. Taking Angola and Brazil as case studies this thesis
argues that differences in the institutional structure of the oil industry in each country,
determined different outcomes regarding Beijingâs oil security goals. This thesis has found that
although this template fitted well with the more centralised institutional environment in Angola,
it was highly unsuitable for the more liberal and regulated Brazil setting. Furthermore, the advent
of the recent global economic crisis (2008-2009) caused China to adjust its approach to the
institutional particulars of Brazil becoming more efficient in that country regarding its oil
security goals.
Building on foreign policy analysis tools and concepts, an empirical analysis of the interplay
between Chinese infrastructure-for-oil loans (hereby regarded as positive economic statecraft)
and the institutional structure it met in each country, is presented. Through the case studies, this
thesis aims to uncover to what extent the institutional context constrained Chinese oil diplomacy
efficiency in Brazil for most of the past decade, and how innovation has surfaced in the context
of the global financial crisis. This analysis thus gives interesting insights not only into the
dynamics of Chinaâs oil diplomacy in Africa and South America, but also into Chinese economic
statecraft in general and how constraints that surface at the implementation level feedback into
foreign policy formulation
Triggering secondary metabolite biosynthesis: exploring the effects of ionic liquids in fungal metabolism
Filamentous fungi are able to synthesise an array of small molecules (secondary
metabolites), which are usually not essential for fungal growth but confer
competitiveness. As a consequence, numerous secondary metabolites remain cryptic
at the artificial conditions of cultivation in a research laboratory. Even in
Aspergillus nidulans, one of the most well studied fungi, numerous metabolites
remain unseen. Several strategies have been used to solve this knowledge gap, some
of which require prior knowledge of genomic sequences, relying on manipulation of
targeted genes encoding components of either secondary metabolism or regulatory
pathways. Other approaches may be applied also in less well characterised strains,
such as cultivation with other species/organisms or modification of the growth
media composition. (...
Role of apoptotic regulators in the protective effect of acetic acid against ethanol - induced cell death in Saccharomyces cerevisiae
Dissertação de mestrado em BioquĂmica AplicadaEthanol is a well-know end product of alcoholic fermentation carried by Saccharomyces
cerevisiae. At relatively low concentrations it is an inhibitor of yeast growth, while, high ethanol
concentrations reduces cell viability (Birch and Walker, 2000). During fermentation, acetic acid
produced by yeast metabolism may accumulate in growth medium and enhance ethanol toxicity
(Gibson et al., 2007). By contrast, studies conducted in our laboratory have shown that S. cerevisiae
cells exposed simultaneously to toxic concentrations of ethanol and low concentrations of acetic acid
displayed a higher survival than cells treated only with ethanol (Vieira et al., unpublished results).
Later, Trindade showed that Hog1p and Fps1p, involved in acetic acid resistance, do not have a role
in the protective effect of acetic acid seen by Vieira (Trindade, 2009). Subsequently, it was also
shown that the osmolyte trehalose, the heat shock protein Hsp12p, the MAP kinase Slt2/MPK1 and
functional mitochondria play a role in the protection by the undissociated form of acetic acid against
ethanol induced cytotoxicity (Afonso, 2011).
With the present master thesis we intended to further understand how acetic acid protects
against ethanol-induced cytotoxicity, determining the role of known apoptotic regulators in this
protection. We also intended to characterize the death of cells exposed to toxic concentrations of
ethanol since this knowledge is important to dissect the role of acetic acid in its inhibition.
This study showed that the deletion in CYC3 or ATP2, ATP10 and NUC1 abolish and
decrease, respectively, the protection of acetic acid against loss of cell viability, loss of plasma
membrane integrity and the accumulation of superoxide anion, induced by ethanol. Death induced by
ethanol was associated with typical markers of apoptosis but also of necrosis. In particular caspase
activation and exposure of phosphatidylserine was detected mainly in cells with compromised plasma
membrane, but also HMGB1/Nhp6A translocates from the nucleus to the cytosol in response to
ethanol. Moreover, the absence of known apoptotic regulatory proteins abrogate (atp2Î, atp10Î,
cyc3Î, por1Î, cpr3Î and yca1Î mutants), exacerbate (aif1Î, nuc1Î, and cyc1Îcyc7Î mutants)
or have no effect (pep4Î mutant) in ethanol induced cell death. Altogether the results obtained with
the mutants phenotypes and the characterization of cell death markers indicate that ethanol triggers
a regulated cell death process that shares features typical of both apoptosis and necrosis. Whether the necrotic features reflect a programmed necrosis or a secondary necrosis of apoptotic cells
committed to death in response to ethanol, requires further studies.O etanol é um produto final bem conhecido da fermentação alcoólica conduzida por
Saccharomyces cerevisiae . Em concentraçÔes relativamente baixas é um inibidor do crescimento da
levedura, enquanto em concentraçÔes elevadas induz perda da viabilidade celular (Birch e Walker,
2000). Durante a fermentação, o åcido acético produzido pelo metabolismo da levedura pode
acumular-se no meio extracelular e aumentar a toxicidade de etanol (Gibson et al., 2007). Por outro
lado, estudos realizados no nosso laboratório mostraram que células de S. cerevisiae
simultaneamente expostas a concentraçÔes tóxicas de etanol e baixas concentraçÔes de åcido
acĂ©tico exibiam uma maior sobrevivĂȘncia do que aquelas tratadas apenas com etanol. (Vieira et. al.,
resultados nĂŁo publicados). Mais tarde, Trindade mostrou que as proteĂnas Hog1p e Fps1p,
envolvidas na resistĂȘncia ao ĂĄcido acĂ©tico, nĂŁo apresentam um papel no efeito protetor do ĂĄcido
acético observado por Vieira (Trindade, 2009). Posteriormente, mostrou-se que o osmólito trealose,
a proteĂna de choque tĂ©rmico Hsp12p, a MAP quinase Slt2/MPK1 e mitocĂŽndrias funcionais tĂȘm um
papel na proteção da forma não dissociada do åcido acético contra citotoxicidade induzida por etanol
(Afonso, 2011).
Com a presente dissertação de mestrado pretendeu-se compreender melhor como o åcido
acético protege contra a citotoxicidade induzida por etanol, determinando o papel de reguladores
conhecidos da apoptose nesta proteção. Também se pretendeu caracterizar a morte de células
expostas a concentraçÔes tóxicas de etanol uma vez que este conhecimento é importante para
dissecar o papel do åcido acético, na sua inibição.
Este estudo mostrou que a ausĂȘncia dos genes CYC3 ou ATP2, ATP10 e NUC1 elimina e
diminui, respetivamente, a proteção do åcido acético contra a perda induzida pelo etanol da
viabilidade celular, da integridade da membrana plasmåtica e da acumulação de anião superóxido. A
morte induzida pelo etanol foi acompanhada de marcadores celulares tĂpicos de apoptose, mas
também de necrose. Em particular foi detetada ativação de caspases e exposição de fosfatidilserina
principalmente em células com a membrana plasmåtica comprometida, mas também a
translocação do HMGB1/Nhp6A do nĂșcleo para o citosol em resposta ao etanol. Adicionalmente, a
ausĂȘncia de reguladores apoptĂłticos reduziram (nos mutantes atp2Î, atp10Î, cyc3Î, por1Î,
cpr3Î e yca1Î), potenciaram (nos mutantes aif1Î, nuc1Î, e cyc1Îcyc7Î ) ou nĂŁo afetaram a sobrevivĂȘncia celular (no mutante pep4Î) em resposta ao etanol. Os resultados respeitantes aos
fenótipos dos mutantes estudados e à caracterização dos marcadores de morte celular indicam que
o etanol induz uma morte regulada que partilha caracterĂsticas tĂpicas de apoptose e necrose. Se as
caracterĂsticas de necrose refletem uma necrose programada ou uma necrose secundĂĄria de cĂ©lulas
que desencadearam um processo de morte apoptĂłtico, requer mais estudos no futuro.Fundação para a CiĂȘncia e a Tecnologia (FCT) - Projeto PEst- C/BIA/UI4050/2011, FCOMP-01-0124-FEDER-007047 e PTDC/AGR- ALI/102608/2008.FEDER atravĂ©s do POFCâCOMPET
EstratĂ©gias de aprendizagem da produção oral em lĂngua estrangeira : um estudo de caso no 2.Âș ciclo do ensino bĂĄsico
Dissertação de Mestrado em Educação - Ărea de Especialização em SupervisĂŁo PedagĂłgica em Ensino das LĂnguas EstrangeirasO estudo aqui apresentado tem por tema as estratĂ©gias de aprendizagem que os
alunos mobilizam em actividades didĂĄcticas de produção oral em LE (InglĂȘs). Trata-se
de um estudo de caso de natureza interpretativa, realizado numa turma do 2Âș Ciclo do
Ensino BĂĄsico (5Âș ano de escolaridade), no qual a professora assume o estatuto de
investigadora participante.
A competĂȘncia da oralidade desempenha um papel importante na formação
integral do aluno a par de outras competĂȘncias de comunicação (ouvir, ler e escrever),
importĂąncia essa que nem sempre lhe Ă© atribuĂda nas aulas e manuais do 2.Âș Ciclo de
Ensino BĂĄsico, sendo ainda escasso o conhecimento dos professores acerca dos
processos de produção oral dos seus alunos. Através do desenho e implementação de
actividades didåcticas com enfoque na produção oral em interacção, procurou-se
identificar as estratégias de aprendizagem que os alunos mobilizam nessas actividades,
no sentido de melhorar a prĂĄtica e alargar a compreensĂŁo sobre processos de
aprendizagem. Foi também nossa intenção contribuir para o desenvolvimento de uma
estratégia de auto-supervisão em contexto pedagógico, dando a conhecer uma hipótese
de trabalho sobre a promoção e regulação da competĂȘncia da oralidade.
A recolha de informação teve como suporte o preenchimento de questionårios
sobre percepçÔes, atitudes e expectativas dos alunos face à aprendizagem da LE, com
enfoque na produção oral em interacção, um questionårio de regulação de estratégias de
aprendizagem da produção oral em interacção e entrevistas de reflexão sobre o uso
dessas estratégias.
A anålise da informação recolhida permite constatar que os alunos manifestam
atitudes bastante favoråveis à aprendizagem da LE. As estratégias de produção oral a
que dizem recorrer nas actividades de produção oral são sobretudo de tipo indirecto, o
que sugere a necessidade de trabalhar mais as estratégias directas em contexto
pedagĂłgico. O estudo parece validar uma abordagem de auto-supervisĂŁo que pode
apoiar os professores na compreensĂŁo dos processos de aprendizagem dos seus alunos e
promover o desenvolvimento de capacidades de auto-regulação desses processos.The present study is focused on the learning strategies of oral production that
students use in FL (English) speaking activities in the classroom. It is an interpretative
case study conducted in a class of 5th grade students, where the teacher was a participant
researcher.
Although oral production plays an important role in the integral development of
students along with other language skills (listening, reading and writing), that is not
always evident in foreign language lessons and course books for beginners, and
teachersâ knowledge of studentsâ learning processes within oral production is often
scarce. Through the design and implementation of activities focused on oral production,
we tried to identify the learning strategies that students use in speaking activities in
order to improve practice and expand our understanding of their learning processes. At
the same time, it was our intention to develop a self-supervision strategy that represents
a working hypothesis to promote and regulate oral production processes in pedagogical
settings.
Data collection was based on student questionnaires about perceptions, attitudes
and expectations towards foreign language learning, with a particular focus on oral
production within interactive activities, a student self-regulation questionnaire on
learning strategies of oral production, and student oral reflections in interviews on the
use of those strategies.
Data analysis shows that the students hold positive attitudes towards foreign
language learning. As regards oral production, they refer mostly to the use of indirect
strategies, which suggests the need to explore further the use of direct strategies in
pedagogical contexts. The study seems to validate a self-supervision approach that may
both enhance teachersâ understanding of studentsâ learning processes and promote the
development studentsâ self-regulation abilities
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