14,080 research outputs found
Brazilian elections: voting for a scaling democracy
The proportional elections held in Brazil in 1998 and 2002 display identical
statistical signatures. In particular, the distribution of votes among
candidates includes a power-law regimen. We suggest that the rationale behind
this robust scaling invariance is a multiplicative process in which the voter's
choice for a candidate is governed by a product of probabilities.Comment: 4 pages, 2 figure
Fractal analyses of networks of integrate-and-fire stochastic spiking neurons
Although there is increasing evidence of criticality in the brain, the
processes that guide neuronal networks to reach or maintain criticality remain
unclear. The present research examines the role of neuronal gain plasticity in
time-series of simulated neuronal networks composed of integrate-and-fire
stochastic spiking neurons, and the utility of fractal methods in assessing
network criticality. Simulated time-series were derived from a network model of
fully connected discrete-time stochastic excitable neurons. Monofractal and
multifractal analyses were applied to neuronal gain time-series. Fractal
scaling was greatest in networks with a mid-range of neuronal plasticity,
versus extremely high or low levels of plasticity. Peak fractal scaling
corresponded closely to additional indices of criticality, including average
branching ratio. Networks exhibited multifractal structure, or multiple scaling
relationships. Multifractal spectra around peak criticality exhibited elongated
right tails, suggesting that the fractal structure is relatively insensitive to
high-amplitude local fluctuations. Networks near critical states exhibited
mid-range multifractal spectra width and tail length, which is consistent with
literature suggesting that networks poised at quasi-critical states must be
stable enough to maintain organization but unstable enough to be adaptable.
Lastly, fractal analyses may offer additional information about critical state
dynamics of networks by indicating scales of influence as networks approach
critical states.Comment: 11 pages, 3 subfigures divided into 2 figure
Translational and rotational motions of albumin sensed by a non-covalent associated porphyrin under physiological and acidic conditions: a fluorescence correlation spectroscopy and time resolved anisotropy study.
The interaction between a free-base, anionic water-soluble porphyrin, TSPP, and the drug carrier protein, bovine serum albumin (BSA) has been studied by time-resolved fluorescence anisotropy (TRFA) and fluorescence correlation spectroscopy (FCS) at two different pH-values. Both rotational correlation times and translational diffusion times of the fluorescent species indicate that TSPP binding to albumin induces very little conformational changes in the protein under physiological conditions. By contrast, at low pH, a bi-exponential decay is obtained where a short rotational correlation time (Âż intÂż=Âż1.2 ns) is obtained, which is likely associated to wobbling movement of the porphyrin in the protein binding site. These physical changes are corroborated by circular dichroism (CD) data which show a 37% loss in the protein helicity upon acidification of the medium. In the presence of excess porphyrin formation of porphyrin J-aggregates is induced, which can be detected by time-resolved fluorescence with short characteristic times. This is also reflected in FCS data by an increase in molecular brightness together with a decrease in the number of fluorescent molecules passing through the detection volume of the sampl
Organisational Ambidexterity in SME Context: A Multi-Level Perspective Focused on Portuguese Technological Firms
The study of organisational ambidexterity (OA) has been an important field of research
for management, especially because of the importance of this theme for the
competitiveness of companies. In this sense, this doctoral thesis in Management has, as
its main objective, to provide a better understanding of how OA can be developed in the
context of Portuguese small and medium-sized enterprises (SME). This study adopted a
multilevel perspective, having explored a set of different paths implemented through
five research articles: a literature review article, a theoretical article and three empirical
articles.
Thus, the first article is a literature review, and its main objective is to identify the
factors that affect OA in SMEs. Based on 297 articles published between 2005 and
2020 in the Web of Science, Scopus and Science Direct databases, a multilevel
perspective was adopted, covering the organisational, environmental, and individual
levels. With this approach, four thematic areas were identified with which the OA
investigation is related: innovation, organisational learning, dynamic capabilities, and
SME performance. The main contribution of this research focuses on the identification
of thematic areas of scientific research around OA, as well as the identification of a set
of contingent factors, located at the organisational, environmental, and individual
levels, which can potentially influence the development of OA in the context of SMEs.
The second article sought to analyse the antecedents of OA considering the main
characteristics of SMEs, such as their small size or their reduced internal structure. For
this purpose, and based on the identified literature, an approach was adopted based on
internal and external antecedents and what is its potential relationship with the
characteristics of SMEs from the perspective of the exploration and exploitation
concepts. Based on this relationship, ten theoretical propositions were identified.
The third article is empirical in nature and adopts an individual-level perspective and
aimed to analyse the influence of owner-managers' personality in the development of
OA in the context of SMEs. For this purpose, five hypotheses based on personality traits
and their influence on OA were formulated. A second-order structural equation model
was used, and a structured questionnaire addressed to the owner-managers of 224
Portuguese SMEs in the information technology (IT), telecommunications, audio-visual and IT consulting. The results obtained suggest the positive influence of the personality
traits of extraversion and conscientiousness in OA and the negative influence of the
personality trait of neuroticism in OA.
The fourth article is also empirical in nature and sought to study the influence of
environmental dynamism and technological capability in OA and the moderating role
of environmental dynamism in OA. With this objective, a second-order structural
equation model was used, and a structured questionnaire addressed to the ownermanagers
of 224 Portuguese SMEs in the information technology (IT),
telecommunications, audio-visual and IT consulting sector. The main results obtained
reveal a positive effect of technological capability in OA as well as a moderating effect
on the relationship between technological capability and OA.
Finally, the fifth and last article adopts an organisational level perspective and aimed to
understand how Quality Management Systems based on ISO 9001 (QMS) can help
inhibit or facilitate OA in SMEs. In this article, a qualitative approach was adopted,
using four case studies and a interview protocol previously developed for this purpose.
The results obtained highlight the importance of the changes caused by the QMS for the
development of ambidextrous behaviours in SMEs and reveal that not all the changes
caused by the QMS in SMEs acted as facilitators of the OA.
The different studies carried out within the scope of this research lead us to consider
that the development of OA in the context of SMEs is dependent on a set of factors of a
multilevel nature, namely in terms of the specific characteristics of this type of
companies, personality traits of the owner-managers and the external influence of the
environmental dynamism in which these companies operate. This study was based on
an important set of theories, such as the Contingency Theory, the Dynamic Capabilities
Theory, the Upper Echelons Theory, or the model of the five factors or personality traits
(Big-Five personality traits).
This PhD thesis in Management supports the idea that the development of OA in SMEs
is dependent on the degree of influence of activities related to exploration and
exploitation. This study suggests that OA is a complex phenomenon, and that
exploration and exploitation will tend to be difficult to balance, which leads us to think
that in SMEs these activities can be balanced alternately or that they can coexist in a
complementary and orthogonal way. In this sense, this study highlights the role of SMEs in customer relationships, the
influence of contingent factors such as environmental dynamism in exploration and
exploitation, the external influence on OA and in the technological capacity of these
companies, as well as the influence of the characteristics of the personality of its ownermanagers.
This investigation also presents contributions to theory and practice, as well
as future lines of research related to this theme.O estudo da ambidextria organizacional tem sido um importante campo de pesquisa
para a gestão, sobretudo pela importância que esta temática se reveste para a
competitividade das empresas. Neste sentido, esta tese de doutoramento em GestĂŁo
possui, como objetivo principal, proporcionar um melhor entendimento acerca da
ambidextria organizacional (AO) em contexto de pequenas e médias empresas (PME)
portuguesas. O caminho de investigação definido adotou uma abordagem multinĂvel,
tendo sido explorados um conjunto de diferentes perspetivas concretizadas através de
cinco artigos de investigação: um artigo de revisão de literatura, um artigo teórico e três
artigos de natureza empĂrica.
Assim, o primeiro artigo, Ă© uma revisĂŁo da literatura e tem como principal objetivo
identificar os fatores que afetam a AO em contexto de PME. Tendo por base 297 artigos
publicados entre 2005 e 2020 nas bases de dados Web of Science, Scopus e Science
Direct, foi adotada uma perspetiva multinĂvel, abrangendo o nĂvel organizacional,
ambiental e individual. Com essa abordagem identificaram-se quatro áreas temáticas
com as quais a investigação da AO se encontra relacionada: inovação, aprendizagem
organizacional, capacidades dinâmicas e desempenho das PME. O principal contributo
desta investigação centra-se na identificação das grandes áreas temáticas de
investigação cientĂfica em torno da AO, assim como a identificação de um conjunto de
fatores contingenciais, situados ao nĂvel organizacional, ambiental e individual, que
potencialmente podem influenciar o desenvolvimento da AO em contexto de PME.
O segundo artigo procurou analisar os antecedentes da AO Ă luz das principais
caracteristicas das PME, como a sua reduzida dimensĂŁo ou a sua reduzida estrutura
interna. Para esse efeito, e tendo por base a literatura identificada, adotou-se uma
abordagem baseada nos antecedentes internos e externos e qual o seu potencial
relacionamento com as caracteristicas das PME sob o prisma dos conceitos de
exploration e exploitation. Com base nesses relacionamentos foram identificadas dez
proposições teóricas.
O terceiro artigo tem uma natureza empĂrica, adota uma perspetiva de nĂvel individual,
e teve como objetivo analisar a influência da personalidade dos proprietários-gestores
no desenvolvimento da AO em contexto de PME. Para esse efeito foram formuladas cinco hipóteses baseadas nos traços de personalidade e a sua influência em AO.
Recorreu-se a um modelo de equações estruturais de segunda ordem e a um
questionário estruturado dirigido aos proprietários-gestores de 224 PME portuguesas
do setor das tecnologias de informação (TI), telecomunicações, audiovisual e
consultadoria em TI. Os resultados obtidos sugerem a influência positiva dos traços de
personalidade da extroversão e conscienciosidade em AO e influência negativa do traço
de personalidade de neuroticismo em AO.
O quarto artigo tem igualmente uma natureza empĂrica e procurou-se estudar a
influĂŞncia do dinamismo ambiental e da capacidade tecnolĂłgica em AO e o papel
moderador do dinamismo ambiental em AO. Com este objetivo recorreu-se a um
modelo de equações estruturais de segunda ordem e a um questionário estruturado
dirigido aos proprietários-gestores de 224 PME portuguesas do setor das tecnologias de
informação (TI), telecomunicações, audiovisual e consultadoria em TI. Os principais
resultados obtidos revelam um efeito positivo da capacidade tecnolĂłgica em AO assim
como um efeito moderador na relação entre capacidade tecnológica e AO.
Por fim, o quinto e Ăşltimo artigo, adota a perspetiva de nĂvel organizacional e teve como
objetivo perceber como os Sistemas de GestĂŁo da Qualidade baseados na ISO 9001
(SGQ) podem ajudar a inibir ou a facilitar a AO em PME. Para este artigo adotou-se
uma abordagem qualitativa, com recurso a quatro estudos de caso e a um questionário
de entrevista previamente desenvolvido para o efeito. Os resultados obtidos ressaltam a
importância das mudanças provocadas pelos SGQ para o desenvolvimento de
comportamentos ambidextros nas PME e revela que nem todas as mudanças
provocadas pelos SGQ nas PME atuaram como facilitadores da AO.
Os diferentes estudos efetuados no âmbito desta investigação leva-nos a considerar que
desenvolvimento da AO no contexto das PME encontra-se dependente de um conjunto
de fatores de natureza multinĂvel, nomeadamente ao nĂvel das caracterĂsticas
especificas deste tipo de empresas, dos traços de personalidade dos seus proprietáriosgestores
e da influĂŞncia externa do dinamismo ambiental onde estas empresas se
inserem. Esta investigação teve por base um importante conjunto de teorias, como a
Teoria Contingencial, a Teoria das Capacidades Dinâmicas, a Upper Echelons Theory,
ou o modelo dos cinco fatores ou traços de personalidade (Big-five personality traits).
Esta tese de doutoramento em GestĂŁo permite sustentar a ideia de que o
desenvolvimento da AO nas PME encontra-se dependente do grau de influĂŞncia das
atividades relacionadas com exploration e exploitation. Este estudo sugere que a AO Ă© um fenĂłmeno complexo e que exploration e exploitation tenderĂŁo a ser difĂceis de
serem equilibradas, o que nos leva a pensar que, nas PME, essas atividades poderĂŁo ser
balanceadas alternadamente ou que poderĂŁo coexistir de forma complementar e
ortogonal.
Neste sentido, este estudo realça o papel das PME no relacionamento com clientes, a
influĂŞncia dos fatores contingenciais como o dinamismo ambiental em exploration e
exploitation, a influência externa na construção da AO e na capacidade tecnológica
destas empresas, assim como a influĂŞncia das caracteristicas de personalidade dos seus
gestores-proprietários. Esta investigação também apresenta contributos para a teoria e
para a prática, assim como linhas de pesquisa futuras relativas a esta temática
Who is the “good citizen”?
The figure of the so-called “good citizen” constitutes a type of ideological discursive strategy and expresses a social pathology of Brazilian citizenship. The aim of this essay is to subject this figure to a critical analysis of its discursive, historical, moral and political assumptions. For this, we resort to the model of immanent critique of ideology proposed by Rahel Jaeggi. We identified contradictions and problems arising from the rhetorical use of the figure of “good citizen” related to: the punitive and firearms appeal to civilians; the ideological representations of gender, race and class; the social function of the media; and political neoconservatism. The fundamental contradiction of the “good citizen” is not in relation to the figure of “bandit” or “bum,” but to the very ideal of universalization of citizenship. As an expression of ideology, the “good citizen” proved to be a real anti-citizen and, therefore, a risk for democracy.A figura do chamado “cidadĂŁo de bem” constitui um tipo de estratĂ©gia discursiva ideolĂłgica e expressa uma patologia social da cidadania brasileira. O objetivo deste ensaio Ă© submeter essa figura a uma análise crĂtica de seus pressupostos discursivos, histĂłricos, morais e polĂticos. Para tanto, recorremos ao modelo de crĂtica imanente da ideologia proposto por Rahel Jaeggi. Identificamos contradições e problemas decorrentes do uso retĂłrico da figura do “cidadĂŁo de bem” relacionadas: ao apelo punitivista e por armas de fogo para civis; Ă s representações ideolĂłgicas de gĂŞnero, raça e classe; Ă função social da mĂdia; e ao neoconservadorismo polĂtico. A contradição fundamental do “cidadĂŁo de bem” nĂŁo Ă© em relação Ă figura do “bandido” ou “vagabundo”, mas ao prĂłprio ideal de universalização da cidadania. Enquanto expressĂŁo da ideologia, o “cidadĂŁo de bem” se revela um verdadeiro anticidadĂŁo e, portanto, um risco para a democracia
Salud mental y bienestar laboral en tiempos de pandemia: revisión sistemática de cómo afrontan los profesionales de la salud el COVID-19: Saúde mental e bem-estar no trabalho em tempos de pandemia: uma revisão sistemática de como os profissionais de saúde estão lidando com a COVID-19
En medio de la pandemia, trabajadores de la salud buscan mĂ©dicos, psicĂłlogos y psiquiatras imbuidos de temor por el Covid-19. Son comunes los informes de cargos abusivos, amenazas y humillaciones en el trabajo, porque además de los trabajadores esenciales, como proclama nuestra ConstituciĂłn Federal de Brasil, los jefes, los gerentes olvidan que estos trabajadores son seres humanos, poseedores de subjetividad, miedos, angustias y ansiedades. El objetivo de esta investigaciĂłn fue evaluar cĂłmo un hospital puede contribuir al bienestar de la salud mental de los profesionales que trabajan en la primera lĂnea contra el coronavirus, haciendo que el Sars-Cov-2 sea parte del trabajo cotidiano. El análisis de los resultados identificĂł que, además del miedo impuesto por la enfermedad, los trabajadores de la salud deben lidiar con el posible contagio, además de la sutil incomprensiĂłn y el acoso moral en la rutina de estos profesionales, convirtiĂ©ndolos en vĂctimas angustiadas, asqueadas, con sentimientos discapacidad y trastornos psicolĂłgicos
Non-local modelling of ductile damage : formulation and numerical issues
Tese de doutoramento. Engenharia Mecânica. Universidade do Porto. Faculdade de Engenharia. 201
Humanismo, diáspora e ciência: séculos XVI e XVII: estudos, catálogo, exposição
Resumo indisponĂvel
Simplified model for the non-linear behaviour representation of reinforced concrete columns under biaxial bending
In the present paper a simplified model is proposed for the force-deformation behaviour of reinforced concrete members under biaxial loading combined with axial force. The starting point for the model development was an existing fixed-length plastic hinge element model that accounts for the non-linear hysteretic behaviour at the element end-sections, characterized by trilinear moment-curvature laws. To take into account the section biaxial behaviour, the existing model was adopted for both orthogonal lateral directions and an interaction function was introduced to couple the hysteretic response of both directions.
To calibrate the interaction function it were used numerical results, obtained from fibre models, and experimental results. For the parameters identification, non-linear optimization approaches were adopted, namely: the gradient based methods followed by the genetic, evolutionary and nature-inspired algorithms.
Finally, the simplified non-linear model proposed is validated through the analytical simulation of biaxial test results carried out in full-scale reinforced concrete columns
Derrame pericárdico em cães e gatos
Dissertação de Mestrado Integrado em Medicina VeterináriaO derrame pericárdico Ă© a afeção pericárdica mais comum em cĂŁes e gatos, consistindo na acumulação excessiva de lĂquido no espaço pericárdico. Em cĂŁes, predominam os derrames sanguinolentos de origem neoplásica ou de origem idiopática. O derrame pericárdico de etiologia neoplásica está associado a um mau prognĂłstico, contrariamente Ă pericadite idiopática. Em gatos, a principal causa de derrame pericárdico Ă© a insuficiĂŞncia cardĂaca congestiva. A neoplasia cardĂaca mais comum em cĂŁes Ă© o hemagiossarcoma; em gatos, Ă© o linfoma. A ecocardiografia Ă© considerada essencial para a identificação destes derrames, tendo sensibilidade e especificidade elevadas para a detecção de massas cardĂacas. Em caso de tamponamento, Ă© necessária pericardiocentese.
Esta dissertação inclui um estudo retrospectico de 18 cĂŁes com derrame pericárdico. Os critĂ©rios de inclusĂŁo foram a realização de ecocardiografia, confirmando a presença do derrame, e a realização pericardiocentese. A maioria dos cĂŁes era de raça identerminada (n=7), seguida das raças Labrador Retriever (4) e Bull Terrier (2); o peso mĂ©dio foi 31 kg, o nĂşmero de machos igualou o das fĂŞmeas, e a idade mĂ©dia foi 10 anos. Os sinais clĂnicos mais frequentes foram intolerância ao exercĂcio (n=13), distenção abdominal (11) e letargia/prostração (10). A neoplasia cardĂaca foi a principal etiologia (n=11), seguida da pericardite idiopática (4). Foram mais frequentes as massas cardĂacas localizadas na base do coração (6), comparativamente Ă s massas no átrio direito (3). Os dignĂłsticos foram maioritariamente presumptivos. Onze cĂŁes morreram (eutanásia em 8) e apenas um continuava vivo durante o estudo. NĂŁo se obteve o desfecho para 6 cĂŁes.
No Ăşltimo capĂtulo consta a descrição do caso de um gato com mesotelioma pericárdico do tipo sarcomatĂłide. Este animal tambĂ©m apresentava derrame pericárdico. Os principais sinais clĂnicos foram anorexia, perda de peso e intolerância ao excercĂcio. O exame ecocardiográfico identificou o derrame, bem como as lesões neolpásicas. O gato morreu 3 dias depois do diagnĂłstico. Ao exame post mortem, a superfĂcie cardĂaca encontrava-se coberta de formações nodulares, firmes e esbranquiçadas. Foi feita análise histopatĂłgica, incluindo estudos imunohistoquĂmicos. O diagnĂłstico de mesotelioma baseou-se na marcação simultânea de citoqueratina (AE1/AE3/PKC26) e de vimentina (V9); as caracterĂsticas histolĂłgicas desta neoplasia confirmaram o seu carácter sarcomatĂłide. Os mesoteliomas cardĂacos sĂŁo raros em gatos e o prognĂłstico nĂŁo Ă© animador.ABSTRACT - Pericardial effusion in dogs and cats - Pericardial effusion is the most common pericardial disorder in dogs and cats. It is defined as excess or abnormal fluid accumulation in the pericardial sac. In dogs, most pericardial effusions are of neoplastic or idiopathic aetiology, and usually sanguineous. The neoplastic cause is associated with a poor prognosis, contrasting with idiopathic pericarditis. In cats, pericardial effusions are most commonly associated with congestive heart failure. Hemangiossarcoma is the most common cardiac neoplasm in dogs, and lymphoma is the most common in cats. Echocardiography is considered essential for pericardial effusion diagnosis, and it has high sensitivity and specificity for cardiac masses detection. Animals with cardiac tamponade should be treated with pericardiocentesis.
The present dissertation contains a retrospective study about 18 dogs with pericardial effusion. Dogs where included when echocardiography (confirming the effusion) and pericardiocentesis were performed. Mixed breed dogs were more frequent (n=11), followed by Labrador Retrievers (4) and Bull Terriers (2); the average weight was 31 kg, males and females where equally represented, and the average age was 10 years. The most common presenting clinical signs included exercise intolerance (n=13), abdominal distension (11) and lethargy/prostration (10). Cardiac neoplasia was the main cause (n=11), followed by idiopathic pericarditis (4). Heart base masses were more common (6) when compared with right atrial masses (3). In this study, most diagnoses were presumptive. Eleven dogs died (8 euthanized) and only one dog was alive during the study. For 6 dogs it was not possible to close the case.
The last chapter of this dissertation contains a case report of pericardial sarcomatoid mesothelioma in a cat. This animal also had pericardial effusion. The main presenting complaints were anorexia, weight loss and exercise intolerance. Echocardiography revealed pericardial effusion and neoplastic lesions. The cat died 3 days after the presentation and diagnosis. The post mortem exam revealed several nodules covering the heart surface; they were firm and whitish. Histopathological and immunohistochemical exams were performed. Concerning immunohistochemistry, the coexpression of cytokeratin (AE1/AE3/PKC26) and vimentin (V9) supported the diagnosis of mesothelioma; histopathologic examination established the mesothelioma subtype (sarcomatoid). Mesotheliomas are rare tumours in domestic cats, and they have poor prognosis.N/
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