Enlarging the window for radiative leptogenesis

We investigate the scenario of resonant thermal leptogenesis, in which the leptonic asymmetries are generated through renormalization group corrections induced at the leptogenesis scale. In the framework of the standard model extended by three heavy Majorana neutrinos with masses M(1) = M(2) << M(3) at some high scale, we show that the mass splitting and CP-violating effects induced by renormalization group corrections can lead to values of the CP asymmetries large enough for a successful leptogenesis. In this scenario, the low-energy neutrino oscillation data can also be easily accommodated. The possibility of having an underlying symmetry behind the degeneracy in the right-handed neutrino mass spectrum is also discussed. (c) 2005 Elsevier B.V. All rights reserved.

A new A(4) model for lepton mixing

We present a new model of the lepton sector that uses a family symmetry A(4) to make predictions for lepton mixing which are invariant under any permutation of the three flavours. We show that those predictions broadly agree with the experimental data, leading to a largish sin(2)theta(12) greater than or similar to 0.34, to vertical bar cos delta vertical bar greater than or similar to 0.7, and to vertical bar 0.5 - sin(2)theta(23)vertical bar greater than or similar to 0.08; cos delta and 0.5 - sin(2)theta(23) are predicted to have identical signs. (C) 2013 Elsevier B.V. All rights reserved.

Anomaly-free U(1) gauge symmetries in neutrino seesaw flavor models

Agência Financiadora: Fundação para a Ciência e a Tecnologia (FCT) - PEst-OE/FIS/UI0777/2013; CERN/FP/123580/2011; PTDC/FIS-NUC/0548/2012

Heterogeneous kinetics of the reduction of chromium (VI) by elemental iron

Zero valent iron (ZVI) has been extensively used as a reactive medium for the reduction of Cr(VI) to Cr(III) in reactive permeable barriers. The kinetic rate depends strongly on the superficial oxidation of the iron particles used and the preliminary washing of ZVI increases the rate. The reaction has been primarily modelled using a pseudo-first-order kinetics which is inappropriate for a heterogeneous reaction. We assumed a shrinking particle type model where the kinetic rate is proportional to the available iron surface area, to the initial volume of solution and to the chromium concentration raised to a power ˛ which is the order of the chemical reaction occurring at surface. We assumed α= 2/3 based on the likeness to the shrinking particle models with spherical symmetry. Kinetics studies were performed in order to evaluate the suitability of this approach. The influence of the following parameters was experimentally studied: initial available surface area, chromium concentration, temperature and pH. The assumed order for the reaction was confirmed. In addition, the rate constant was calculated from data obtained in different operating conditions. Digital pictures of iron balls were periodically taken and the image treatment allowed for establishing the time evolution of their size distribution.

Industrial multimedia over factory-floor networks

In this paper we describe a real-time industrial communication network able to support both controlrelated and multimedia traffic. The industrial communication network is based on the PROFIBUS standard, with multimedia capabilities being provided by an adequate integration of TCP/IP protocols into the PROFIBUS stack. From the operational point of view the integration of TCP/IP into PROFIBUS is by itself a challenge, since the master-slave nature of the PROFIBUS MAC makes complex the implementation of the symmetry inherent to IP communications. From the timeliness point of view the challenge is two folded. On one hand the multimedia traffic should not interfere with the timing requirements of the "native" control-related PROFIBUS traffic (typically hard real-time). On the other hand multimedia traffic requires certain levels of quality-of-service to be attained. In this paper we provide a methodology that enables fulfilling the timing requirements for both types of traffic in these real-time industrial LAN. Moreover, we describe suitable algorithms for the scheduling support of concurrent multimedia streams.

Supporting internet protocols in master-slave fieldbus networks

In this paper we describe how to integrate Internet Protocols (IP) into a typical hierarchical master-slave fieldbus network, supporting a logical ring token passing mechanism between master stations. The integration of the TCP/IP protocols in the fieldbus protocol rises a number of issues that must be addressed properly. In this paper we particularly address the issues related to the conveyance of IP fragments in fieldbus frames (fragmentation/de-fragmentation) and on how to support the symmetry inherent to the TCP/IP protocols in fieldbus slaves, which lack communication initiative.

Laxity dynamics and LLF schedulability analysis on multiprocessor platforms

LLF (Least Laxity First) scheduling, which assigns a higher priority to a task with a smaller laxity, has been known as an optimal preemptive scheduling algorithm on a single processor platform. However, little work has been made to illuminate its characteristics upon multiprocessor platforms. In this paper, we identify the dynamics of laxity from the system’s viewpoint and translate the dynamics into LLF multiprocessor schedulability analysis. More specifically, we first characterize laxity properties under LLF scheduling, focusing on laxity dynamics associated with a deadline miss. These laxity dynamics describe a lower bound, which leads to the deadline miss, on the number of tasks of certain laxity values at certain time instants. This lower bound is significant because it represents invariants for highly dynamic system parameters (laxity values). Since the laxity of a task is dependent of the amount of interference of higher-priority tasks, we can then derive a set of conditions to check whether a given task system can go into the laxity dynamics towards a deadline miss. This way, to the author’s best knowledge, we propose the first LLF multiprocessor schedulability test based on its own laxity properties. We also develop an improved schedulability test that exploits slack values. We mathematically prove that the proposed LLF tests dominate the state-of-the-art EDZL tests. We also present simulation results to evaluate schedulability performance of both the original and improved LLF tests in a quantitative manner.

Dinossáurios Eocretácicos de Lagosteiros

According to an ancient folkloric legend, Our Lady, stepping down from the sea, would have rided on a mule to the platform above the cliffs named Pedra da Mua at Lagosteiros'bay, near Espichel cape. Mule's footprints, regarded by fishermen as evidence, would be clearly recognizable on exposed surfaces of the rocks. Indeed there are footprints but from Dinosaurs of latest Jurassic, Portlandian age, this spectacular locality being specially rich in giant Sauropod tracks (that have seldom been found elsewhere in Europe). As we proceeded to its study, another locality with Dinosaur footprints, Lower Cretaceous (Hauterivian) in age, was found on the northern cliffs at Lagosteiros. It is probably the richest one in european Lower Cretaceous and the only of this age known in Portugal, so we decided to give priority to its study. Dinosaur tracks have been printed on calciclastic sands in a lagoonal environment protected by fringing coral reefs. There have been emersion episodes; beaches were frequented by Dinosaurs. Later on, the marine barremian ingression restablished a gulf and such animals could not come here any more. Under a paleogeographical viewpoint, the evidence of a marine regression near the end of Hauterivian is to be remarked. Five types of tracks and footprints have been recognized: - Neosauropus lagosteirensis, new morphogenus and species, tracks from a giant Sauropod, perhaps from Camarasaurus; with its proportions the total length of the author would be about 15,5 m. These are the only Sauropod tracks known till now in Europe's Lower Cretaceous. - tracks from a not so big quadruped, maybe a Sauropod (young individual?); however it is not impossible that they were produced by Stegosaurians or Ankylosaurians. -Megalosauropus (?Eutynichnium) gomesi new morphospecies, four Theropod tracks most probably produced by megalosaurs. - Iguanodon sp., represented by some footprints and specially by a set corresponding to the feet and tail from an individual standing in a rest position. - problematical, quite small-sized biped (maybe an Ornithopod related to Camptosaurus). Evidence points to a richer fauna than that known in barremian "Dinosaur sandstones" from a nearby locality, Boca do Chapim. Lagosteiros' association clearly indicates the predominance of herbivores, which required large amounts of vegetable food in the neighbourhood. This is an indirect evidence of the vegetal wealth, also suggested by associations of plant macrofossils, polen and spores found in early Cretaceous sediments at the same region. The relatively high proportion of Theropoda is related to the wealth of the whole fauna, which comprised a lot of the prey needed by such powerful flesh-eaters. The evidence, as a whole, points out to a warm and moist climate. All the tracks whose direction could be measured are directed to the southern quadrants, this being confirmed by the approximative direction of other footprints. Massive displacements (migration?) could take place during a brief emersion episode. This may result from the ingression of barremian seas, flooding the region and restablishing here a small gulf. Even if the arrival of the waters damaged certain footprints it has not destroyed them completely, thus allowing the preservation of such evidence from a remote past.

Contributions à la Paléontologie du Miocène moyen continental du Bassin du Tage. I - Quelques mollusques - Pero Filho, Póvoa de Santarém, Sítio do Mirante

Some land and freshwater mollusks (Gastropoda, Pelecypoda) from three middle Miocene localities: Pêro Filho, Póvoa de Santarém, Sítio do Mirante, all in Ribatejo province, Portugal, are summarily studied. On a systematical viewpoint it has been shown (see also Tableau): - the presence of the genus Janulus, whose species only survive now at Madeira and Canary's islands; - the presence of "Helix" cotteri that may indeed belong in the genus Megalotachea, common in western Europe since "Helvetian" to Messinian times; - Limax, Testacella, Acroloxus and Pseudamnicola are quoted for the first time in portuguese tertiary formations; Ferrisia has been identified for the first time in Iberian Peninsule; - the presence of other forms previously quoted by ANTUNES & ZBYSZEWSKI (1973), is confirmed: Bithynia, Theodoxus, Pisidium. Such faunules are compatible with a middle Miocene age. On a paleobiogeographical viewpoint, some forms suggest mediterranean affinities. Fossil associations do correspond ecologically to either palustrine or stagnant, calm and shallow water conditions (Sítio do Mirante, and essentially also Póvoa de Santarém), or to fluviatile conditions (Pêro Filho).

Zinc-substituted desulfovibrio gigas desulforedoxins

Protein Science (2002), 11:2464–2470

Aspect-oriented domain analysis

Dissertação de Mestrado em Engenharia Informática

Complex order biped rhythms

Animal locomotion is a complex process, involving the central pattern generators (neural networks, located in the spinal cord, that produce rhythmic patterns), the brainstem command systems, the steering and posture control systems and the top layer structures that decide which motor primitive is activated at a given time. Pinto and Golubitsky studied an integer CPG model for legs rhythms in bipeds. It is a four-coupled identical oscillators' network with dihedral symmetry. This paper considers a new complex order central pattern generator (CPG) model for locomotion in bipeds. A complex derivative Dα±jβ, with α, β ∈ ℜ+, j = √-1, is a generalization of the concept of an integer derivative, where α = 1, β = 0. Parameter regions where periodic solutions, identified with legs' rhythms in bipeds, occur, are analyzed. Also observed is the variation of the amplitude and period of periodic solutions with the complex order derivative.

Viewpoints and goals: towards an integrated approach

Dissertação de Mestrado em Engenharia Informática

Segmentation of striatal brain structures from high resolution pet images

Dissertation presented at the Faculty of Science and Technology of the New University of Lisbon in fulfillment of the requirements for the Masters degree in Electrical Engineering and Computers

Abelian realization of phenomenological two-zero neutrino textures

In an attempt at explaining the observed neutrino mass-squared differences and leptonic mixing, lepton mass matrices with zero textures have been widely studied. In the weak basis where the charged lepton mass matrix is diagonal, various neutrino mass matrices with two zeros have been shown to be consistent with the current experimental data. Using the canonical and Smith normal form methods, we construct the minimal Abelian symmetry realizations of these phenomenological two-zero neutrino textures. The implementation of these symmetries in the context of the seesaw mechanism for Majorana neutrino masses is also discussed. (C) 2014 The Authors. Published by Elsevier B.V.