The University of Coimbra dɨ kuˈĩbɾɐ]) is a Portuguese public university in Coimbra, Portugal. Established in 1290, it is one of the oldest universities in continuous operation in the world, the oldest university of Portugal, and one of its largest higher education and research institutions. It is organized into eight different faculties according to a wide range of fields, granting academic bachelor's , master's and doctorate degrees in arts, engineerings, humanities, mathematics, natural science, social science, sports and technologies. It is a founding member of the Coimbra Group, a group of leading European research universities, whose inaugural meeting it hosted. The University of Coimbra has approximately 20,000 students, and hosts one of the largest communities of international students in Portugal, being the most cosmopolitan Portuguese university.On 22 June 2013, UNESCO added the university to its World Heritage List. Wikipedia.
Dias A.M.P.G.,University of Coimbra
Journal of Structural Engineering (United States) | Year: 2012
This paper discusses the nonlinear mechanical behavior of timber-concrete structures, mainly when dowel-type fasteners are used in the connections. These nonlinear phenomena result from the nonlinear mechanical behavior of the materials and connections. This paper deals with the connection aspect of the nonlinearity and goes on to present and discuss the causes of such phenomena as well as the approaches available to address them. Since these analyses require an adequate definition of the load-slip behavior of the connection, a numerical model is proposed to derive it, based on either results from experimental tests or numerical models. A calculation example is used to assess the influence of the nonlinear phenomena on the design of this type of structure. From the analysis undertaken, it is concluded that the nonlinear mechanical behavior of the connections may have a significant influence on the mechanical behavior of the composite structures. Moreover, the model proposed to describe the load-slip behavior of the connection is shown to be accurate and effective. © 2012 American Society of Civil Engineers.
Silveirinha M.G.,University of Coimbra
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2014
In open resonators the energy associated with a localized photonic excitation is lost in the form of a radiated wave, in the same manner that a classical charged particle in a curved orbit loses energy in the form of electromagnetic radiation. As a consequence, photonic modes in conventional spatially bounded open resonators have finite decay times. Here, we theoretically show that, surprisingly, in the limit of vanishing material loss, plasmons give the opportunity to have light localization in open spatially bounded systems with infinitely large lifetimes. © 2014 American Physical Society.
Heleno R.H.,University of Coimbra
Proceedings. Biological sciences / The Royal Society | Year: 2013
Alien plants are a growing threat to the Galápagos unique biota. We evaluated the impact of alien plants on eight seed dispersal networks from two islands of the archipelago. Nearly 10 000 intact seeds from 58 species were recovered from the droppings of 18 bird and reptile dispersers. The most dispersed invaders were Lantana camara, Rubus niveus and Psidium guajava, the latter two likely benefiting from an asynchronous fruit production with most native plants, which facilitate their consumption and spread. Lava lizards dispersed the seeds of 27 species, being the most important dispersers, followed by small ground finch, two mockingbirds, the giant tortoise and two insectivorous birds. Most animals dispersed alien seeds, but these formed a relatively small proportion of the interactions. Nevertheless, the integration of aliens was higher in the island that has been invaded for longest, suggesting a time-lag between alien plant introductions and their impacts on seed dispersal networks. Alien plants become more specialized with advancing invasion, favouring more simplified plant and disperser communities. However, only habitat type significantly affected the overall network structure. Alien plants were dispersed via two pathways: dry-fruited plants were preferentially dispersed by finches, while fleshy fruited species were mostly dispersed by other birds and reptiles.
Salvador J.A.,University of Coimbra
Natural product reports | Year: 2012
This review highlights the potential of natural and semisynthetic ursane-type triterpenoids as candidates for the design of multi-target bioactive compounds, with focus on their anticancer effects. A brief illustration of the biosynthesis, sources, and general biological effects of the main classes of naturally occurring pentacyclic triterpenoids (PTs) are provided.
Vidana I.,University of Coimbra
Physical Review C - Nuclear Physics | Year: 2012
We analyze the role of the symmetry energy slope parameter L on the r-mode instability of neutron stars. Our study is performed using both microscopic and phenomenological approaches of the nuclear equation of state. The microscopic ones include the Brueckner-Hartree-Fock approximation, the well known variational equation of state of Akmal, Pandharipande, and Ravenhall, and a parametrization of recent auxiliary field diffusion Monte Carlo calculations. For the phenomenological approaches, we use several Skyrme forces and relativistic mean-field models. Our results show that the r-mode instability region is smaller for those models which give larger values of L. The reason is that both bulk (ξ) and shear (η) viscosities increase with L and, therefore, the damping of the mode is more efficient for the models with larger L. We show also that the dependence of both viscosities on L can be described at each density by simple power-laws of the type ξ=A ξLB ξ and η=A ηLB η. Using the measured spin frequency and the estimated core temperature of the pulsar in the low-mass x-ray binary 4U 1608-52, we conclude that observational data seem to favor values of L larger than ∼50 MeV if this object is assumed to be outside the instability region, its radius is in the range 11.5-12 (11.5-13) km, and its mass 1.4M (2M). Outside this range it is not possible to draw any conclusion on L from this pulsar. © 2012 American Physical Society.