A New Approach to Population Sizing for Memetic Algorithms: A Case Study for the Multidimensional Assignment Problem

Memetic algorithms are known to be a powerful technique in solving hard optimization problems. To design a memetic algorithm, one needs to make a host of decisions. Selecting the population size is one of the most important among them. Most of the algorithms in the literature fix the population size to a certain constant value. This reduces the algorithm's quality since the optimal population size varies for different instances, local search procedures, and runtimes. In this paper we propose an adjustable population size. It is calculated as a function of the runtime of the whole algorithm and the average runtime of the local search for the given instance. Note that in many applications the runtime of a heuristic should be limited and, therefore, we use this bound as a parameter of the algorithm. The average runtime of the local search procedure is measured during the algorithm's run. Some coefficients which are independent of the instance and the local search are to be tuned at the design time;we provide a procedure to find these coefficients. The proposed approach was used to develop a memetic algorithm for the multidimensional assignment problem (MAP). We show that our adjustable population size makes the algorithm flexible to perform efficiently for a wide range of running times and local searches and this does not require any additional tuning of the algorithm

Survey and characterization of corbelled dome architecture in Northwestern Portugal

The act of overlaying stones to build masonry structures is one of mankind’s most intuitive and resourceful achievements. Masonry buildings can be found all over the world, built with a wide diversity of materials and serving for all kind of purposes. In rural northwestern Portugal, in a granitic highland landscape of scarce resources, for centuries, local farmers used masonry in order to make the territory suitable for farming. In their effort to increase production and, by doing so, to improve their living conditions, a specific mountain agro-pastoral system was developed. Supported by communitarian labour, this system was based on terrace farming and temporary mountain plateau settlements, called brandas, composed of granite corbelled dome buildings. In spite of its perfect adaptation to the harsh local conditions, this heritage’s morphological and typological diversity and constructive inventiveness is endangered due to decades of rural exodus and, thus requiring urgent study and protection. The research project aims to study this heritage from morphological, typological and constructive points of view, with the objective of proposing guidelines towards its preservation. To achieve the established goals, a four stage based methodology was established. Literature review and fieldwork surveys were performed in the first stage, in order to identify possible case studies. On the second stage, an exhaustive geometrical survey and a case study analysis were undertaken and complemented with the local granite’s physical and mechanical characterization. The third stage aims to do an overall structural safety evaluation of the corbelled domes, based on numerical analysis. In the final stage, consolidation and preservation guidelines to safeguard this architectural heritage will be proposed. This paper presents the results of the first stage, along with a glimpse of the second stage.The authors wish to express their gratitude to the Municipality of Arcos de Valdevez, for all the support given, and to the Equipa de Sapadores Florestais do Gabinete Técnico Florestal do Município e da Associação Floresta Atlântica. The first and fifth authorswishto express theirgratitude to the Portuguese Science and Technology Foundation for the scholarshipsgranted (SFRH/BD/ 86704/2012 and SFRH/BD/112646/2015).This work was supported by FCT, within ISISE, project UID/ECI/04029/2013

A proactive approach to the conservation of historic and cultural Heritage: The HeritageCare methodology

Presently, no systematic policy for the preventive conservation of the built cultural heritage exists in South-West Europe. Current approaches for inspection, diagnosis, monitoring and reactive conservation are normally intermittent, unplanned, expensive and lack methodical strategy. The available financial resources are scarce and are mostly addressed to listed buildings. Besides, owners and stakeholders often reveal reluctance to invest in preventive conservation and maintenance programs. In view of these considerations, and driven by the principle “prevention is better than cure”, the HeritageCare project has developed a system for the preventive conservation and maintenance of the built heritage. The main aim of this paper is to briefly describe the methodology, including its three levels of service, and present the main results of the implementation and validation of the service level 1 on a case study belonging to the Portuguese architectural heritage.This work was carried out within the scope of the project HeritageCare (SOE1/P5/P0258), co-funded by the Interreg-Sudoe/FEDER program and included in the research activities of the ISISE Research Centre, also financed by FEDER funds through the Competitiveness Factors Operational Program – COMPETE and by national funds through FCT – Foundation for Science and Technology within the scope of the project POCI-01-0145-FEDER-007633. Authors would like to express their gratitude to the Centre for Computer Graphics, HeritageCare partner, for the development of the platform (and supporting database) and the mobile application, outputs of the project HeritageCare. Authors would like to express their gratitude to the Santa Maria de la Real Foundation, HeritageCare partner, for the placement of the monitoring system at the Ducal Palace, Guimarães, Portugal

Casimir energy in multiply connected static hyperbolic Universes

We generalize a previously obtained result, for the case of a few other static hyperbolic universes with manifolds of nontrivial topology as spatial sections.Comment: accepted for publicatio

Immunization expands B cells specific to HIV-1 V3 glycan in mice and macaques.

Broadly neutralizing monoclonal antibodies protect against infection with HIV-1 in animal models, suggesting that a vaccine that elicits these antibodies would be protective in humans. However, it has not yet been possible to induce adequate serological responses by vaccination. Here, to activate B cells that express precursors of broadly neutralizing antibodies within polyclonal repertoires, we developed an immunogen, RC1, that facilitates the recognition of the variable loop 3 (V3)-glycan patch on the envelope protein of HIV-1. RC1 conceals non-conserved immunodominant regions by the addition of glycans and/or multimerization on virus-like particles. Immunization of mice, rabbits and rhesus macaques with RC1 elicited serological responses that targeted the V3-glycan patch. Antibody cloning and cryo-electron microscopy structures of antibody-envelope complexes confirmed that immunization with RC1 expands clones of B cells that carry the anti-V3-glycan patch antibodies, which resemble precursors of human broadly neutralizing antibodies. Thus, RC1 may be a suitable priming immunogen for sequential vaccination strategies in the context of polyclonal repertoires

The impact of low erythrocyte density in human blood on the fitness and energetic reserves of the African malaria vector Anopheles gambiae

Background Anaemia is a common health problem in the developing world. This condition is characterized by a reduction in erythrocyte density, primarily from malnutrition and/or infectious diseases such as malaria. As red blood cells are the primary source of protein for haematophagous mosquitoes, any reduction could impede the ability of mosquito vectors to transmit malaria by influencing their fitness or that of the parasites they transmit. The aim of this study was to determine the impact of differences in the density of red blood cells in human blood on malaria vector (Anopheles gambiae sensu stricto) fitness. The hypotheses tested are that mosquito vector energetic reserves and fitness are negatively influenced by reductions in the red cell density of host human blood meals commensurate with those expected from severe anaemia. Methods Mosquitoes (An. gambiae s.s.) were offered blood meals of different packed cell volume(PCV) of human blood consistent with those arising from severe anaemia (15%) and normalPCV (50%). Associations between mosquito energetic reserves (lipid, glucose and glycogen)and fitness measures (reproduction and survival) and blood meal PCV were investigated. Results The amount of protein that malaria vectors acquired from blood feeding (indexed by haematin excretion) was significantly reduced at low blood PCV. However, mosquitoes feeding on blood of low PCV had the same oviposition rates as those feeding on blood of normal PCV, and showed an increase in egg production of around 15%. The long-term survival of An. gambiae s.s was reduced after feeding on low PCV blood, but PCV had no significant impact on the proportion of mosquitoes surviving through the minimal period required to develop and transmit malaria parasites (estimated as 14 days post-blood feeding). The impact of blood PCV on the energetic reserves of mosquitoes was relatively minor. Conclusions These results suggest that feeding on human hosts whose PCV has been depleted due to severe anaemia does not significantly reduce the fitness or transmission potential of malaria vectors, and indicates that mosquitoes may be able exploit resources for reproduction more efficiently from blood of low rather than normal PCV

The epochs of early-type galaxy formation as a function of environment

The aim of this paper is to set constraints of the epochs of early-type galaxy formation through the 'archaeology' of the stellar populations in local galaxies. Using our models of absorption line indices that account for variable abundance ratios, we derive the stellar population parameters of 124 early-type galaxies in high and low density environments. We find that all three parameters age, metallicity, and alpha/Fe ratio are correlated with velocity dispersion. We further find evidence for an influence of the environment on the stellar population properties. Massive early-type galaxies in low-density environments appear on average ~2 Gyrs younger and slightly more metal-rich than their counterparts in high density environments. No offsets in the alpha/Fe ratios, instead, are detected. We translate the derived ages and alpha/Fe ratios into star formation histories. We show that most star formation activity in early-type galaxies is expected to have happened between redshifts 3 and 5 in high density and between redshifts 1 and 2 in low density environments. We conclude that at least 50 per cent of the total stellar mass density must have already formed at z 1, in good agreement with observational estimates of the total stellar mass density as a function of redshift. Our results suggest that significant mass growth in the early-type galaxy population below z 1 must be restricted to less massive objects, and a significant increase of the stellar mass density between redshifts 1 and 2 should be present caused mainly by the field galaxy population. The results of this paper further imply vigorous star formation episodes in massive objects at z 2-5 and the presence of evolved ellipticals around z 1, both observationally identified as SCUBA galaxies and EROs.Comment: 20 pages, 10 figures, plus appendix, accepted by Ap

The Murchison Widefield Array

It is shown that the excellent Murchison Radio-astronomy Observatory site allows the Murchison Widefield Array to employ a simple RFI blanking scheme and still calibrate visibilities and form images in the FM radio band. The techniques described are running autonomously in our calibration and imaging software, which is currently being used to process an FM-band survey of the entire southern sky.Comment: Accepted for publication in Proceedings of Science [PoS(RFI2010)016]. 6 pages and 3 figures. Presented at RFI2010, the Third Workshop on RFI Mitigation in Radio Astronomy, 29-31 March 2010, Groningen, The Netherland