13,925 research outputs found
A simple deterministic self-organized critical system
We introduce a new continuous cellular automaton that presents self-organized
criticality. It is one-dimensional, totally deterministic, without any kind of
embedded randomness, not even in the initial conditions. This system is in the
same universality class as the Oslo rice pile system, boundary driven interface
depinning and the train model for earthquakes. Although the system is chaotic,
in the thermodynamic limit chaos occurs only in a microscopic level.Comment: System slightly modified. New results on Liapunov exponents.
Submitted for publication (8 pages
Some properties of two Nambu--Jona-Lasinio -type models with inputs from lattice QCD
We investigate the phase diagram of the so-called
Polyakov--Nambu--Jona-Lasinio (PNJL) model at finite temperature and nonzero
chemical potential. The calculations are performed in the light and strange
quark sectors (, , ), which includes the 't Hooft instanton induced
interaction term that breaks the axial symmetry, and the quarks are coupled to
the (spatially constant) temporal background gauge field. On one hand, a
special attention is payed to the critical end point (CEP). The strength of the
flavor-mixing interaction alters the CEP location, since when it becomes weaker
the CEP moves to low temperatures and can even disappear. On the other hand, we
also explore the connection between QCD, a nonlocal Nambu--Jona-Lasinio type
model and the Landau gauge gluon propagator. Possible links between the
quenched gluon propagator and low energy hadronic phenomenology are
investigated.Comment: Contribution to the International Meeting "Excited QCD", Peniche,
Portugal, 06 - 12 May 201
Institutional reorientation: the case of Universidade Aberta
The goal of this study is to provide guidelines for the restructuring process of Universidade Aberta, which is the Portuguese distance learning university. The external and internal assessments were performed using multiple instruments, of which we highlight a survey with responses from over twenty countries. This survey was analyzed using advanced data mining methods along three dimensions: educational offer, target publics and operating model. The specific guidelines are based on the assumption of a certain status quo in the higher education sector
Cooperation and best practices within the COTEC Innovative SME Network
This article investigates what members consider to be the advantages of cooperating with and belonging to the COTEC Innovative SME Network, and identifies which have been and should be the best cooperation practices. These advantages were measured through enquiries conducted at the beginning of 2008 and 2010, while the best practices were assessed by means of both the 2010 enquiry and the Innovation Scoring (IS). The results were not always conclusive or robust; nevertheless, we found that the three main advantages cited in 2008 were repeated in 2010 and that there are a number of statistically significant relationships between some selected advantages and categories such as ICT sector, manufacturing industry or collaborative profile technological partner . Although the crossing of best practices (past and future) with the IS was inconclusive, the results could serve as a reference for COTEC and its members
Chaos and Synchronized Chaos in an Earthquake Model
We show that chaos is present in the symmetric two-block Burridge-Knopoff
model for earthquakes. This is in contrast with previous numerical studies, but
in agreement with experimental results. In this system, we have found a rich
dynamical behavior with an unusual route to chaos. In the three-block system,
we see the appearance of synchronized chaos, showing that this concept can have
potential applications in the field of seismology.Comment: To appear in Physical Review Letters (13 pages, 6 figures
Universal Programmable Quantum Circuit Schemes to Emulate an Operator
Unlike fixed designs, programmable circuit designs support an infinite number
of operators. The functionality of a programmable circuit can be altered by
simply changing the angle values of the rotation gates in the circuit. Here, we
present a new quantum circuit design technique resulting in two general
programmable circuit schemes. The circuit schemes can be used to simulate any
given operator by setting the angle values in the circuit. This provides a
fixed circuit design whose angles are determined from the elements of the given
matrix-which can be non-unitary-in an efficient way. We also give both the
classical and quantum complexity analysis for these circuits and show that the
circuits require a few classical computations. They have almost the same
quantum complexities as non-general circuits. Since the presented circuit
designs are independent from the matrix decomposition techniques and the global
optimization processes used to find quantum circuits for a given operator, high
accuracy simulations can be done for the unitary propagators of molecular
Hamiltonians on quantum computers. As an example, we show how to build the
circuit design for the hydrogen molecule.Comment: combined with former arXiv:1207.174
VENOUS THROMBOEMBOLISM IN CHILDREN
Introdução: O tromboembolismo venoso é uma entidade rara em idade pediátrica, de etiologia multi-fatorial, sendo importante estabelecer o seu diagnóstico e avaliar o prognóstico funcional.
Caso clínico: Adolescente de 11 anos, habitualmente saudável, observada no Serviço de Urgência por clínica compatível com trombose venosa superficial do membro superior. Da investigação realizada, controlo analítico incluindo velocidade de sedimentação, coagulação, auto-imunidade e homocisteína
com valores dentro da normalidade. Efetuado estudo genético de trombofilias, apresentando mutação do gene da protrombina (G20210A, em heterozigotia) e mutações do PAI-1 (4G e -844A), associadas a estado de hipercoagulabilidade, com indicação para profilaxia com heparina de baixo peso molecular em situações de maior risco.
Discussão/Conclusão: A raridade do evento tromboembólico, associada à localização atípica do quadro inaugural, conduziu a uma investigação exaustiva. As alterações da trombofilia podem ter a sua manifestação inicial na adolescência, sendo importante a sua deteção pelas implicações no dia-a-dia do
indivíduo e necessidade de atitudes profiláticas em situações particulares.Introduction: Venous thromboembolism is rare among children and has a multi-factorial aetiology. It’s important to establish the diagnosis and evaluate the functional prognosis.
Case report: A previously healthy 11 year old adolescent was observed in the emergency room with clinical signs of superficial venous thrombosis of the upper limb. Laboratorial evaluation showed a sedimentation rate, coagulation study, autoimmune antibodies and homocysteine with normal values. Testing for heritable thrombophilia revealed prothrombin mutation (G20210A, heterozigosity) and mutation of PAI-1 (4G e -844A), both of which are associated with hypercoagulable state and indication to do prophylaxis with low molecular weight heparin in higher risk situations.
Discussion/Conclusion: The rarity of thromboembolic events at this age and the atypical localization lead to an exhaustive laboratorial evaluation. Thrombophilia mutations may clinically become evident in adolescence, and its detection is important because of children’s lifestyle and the need of prophylactic
treatment in some situations
Implementação da NBR ISO/IEC 17025 estudo de caso: a experiência do laboratório de fitopatologia ? Embrapa ? CNPMF.
No Brasil, a avaliação da competência de laboratórios de ensaios é feita pela CRE/Inmetro, em um processo denominado acreditação, e auditorias são realizadas para determinar a conformidade do sistema de gestão com a NBR ISO/IEC 17025. A acreditação dá ao laboratório reconhecimento nacional/internacional, já que o habilita a fazer parte de uma rede de Laboratórios. Atualmente o Laboratório de Fitopatologia da Embrapa Mandioca e Fruticultura (LFITO) é credenciado pelo Ministério da Agricultura e Pecuária (MAPA) e está pleiteando à acreditação junto ao Inmetro, sendo necessário a implementação de alguns requisitos para atender plenamente a NBR ISO IEC/17025
Ensaios de proficiência em microbiologia: desafio para a acreditação de Laboratórios de Fitossanidade Vegetal
O Ministério da Agricultura Pecuária e Abastecimento no uso de suas atribuições, após ter conferido a laboratórios de ensaios o credenciamento para análises de amostras microbiológicas, tornou necessário aos mesmos a apresentação de comprovante de acreditação junto ao Inmetro na norma ABNT ISO/IEC 17025 a partir da Instrução Normativa nº 34 de 15 de julho de 2011, num prazo de até trinta e seis meses. Entre as exigências documentais do Inmetro aos laboratórios postulantes à acreditação, de acordo com a norma NIT-DICLA-026, está o cumprimento dos requisitos para participação em ensaios de proficiência
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