Efficient coding in dolphin surface behavioral patterns

We show that the law of brevity, i.e. the tendency of words to shorten as their frequency increases, is also found in dolphin surface behavioral patterns. As far as we know, this is the first evidence of the law in another species, suggesting that coding efficiency is not unique to humans.Peer ReviewedPostprint (author's final draft

Long-term correlations in the surface behavior of dolphins

Here we study the sequences of surface behavioral patterns of dolphins (Tursiops sp.) and find long-term correlations. We show that the long-term correlations are not of a trivial nature, i.e. they cannot be explained by the repetition of the same surface behavior many times in a row. Our findings suggest that dolphins have a long collective memory extending back at least to the 7-th past behavior. As far as we know, this is the first evidence of long-term correlations in the behavior of a non-human species.Peer ReviewedPostprint (author's final draft

Long Term Consequences of Natural Resource Booms for Human Capital Accumulation

Tight labour markets driven by resource booms could increase the opportunity cost of schooling and crowd out human capital formation. For oil producing economies like the Province of Alberta, the OPEC oil shocks of 1973 to 1981 may have had an adverse long term effect on the productivity of the labor force if the oil boom resulted in workers reducing their ultimate investment in human capital rather than merely altering the timing of schooling. We analyze the effect of this decade long oil-boom on the long-term human capital investments and productivity for Alberta birth cohorts that were of normal schooling ages before, during and after the oil boom. Our findings suggest that resource booms may change the timing of schooling but they do not reduce the total accumulation of human capital.Resource booms, long term human capital accumulation, OPEC oil crisis

Life cycle assessment of drinking water: comparing conventional water treatment, reverse osmosis and mineral water in glass and plastic bottles

This study evaluated the environmental impacts caused by drinking water consumption in Barcelona (Spain) using the Life Cycle Assessment (LCA) methodology. Five different scenarios were compared: 1) tap water from conventional drinking water treatment; 2) tap water from conventional drinking water treatment with reverse osmosis at the water treatment plant; 3) tap water from conventional drinking water treatment with domestic reverse osmosis; 4) mineral water in plastic bottles, and 5) mineral water in glass bottles. The functional unit was 1 m3 of water. The water treatment plant considered in scenarios 1, 2 and 3, treats around 5 m3 s-1 of surface water. The water bottling plants considered in scenarios 4 and 5 have a production capacity of 200 m3 of bottled water per day. The LCA was performed with the software SimaPro®, using the CML 2 baseline method. The results showed how tap water consumption was the most favourable alternative, while bottled water presented the worst results due to the higher raw materials and energy inputs required for bottles manufacturing, especially in the case of glass bottles. The impacts generated by domestic reverse osmosis were between 10 and 24% higher than tap water alternative depending on the impact category. It was due to the higher electricity consumption. Reverse osmosis at the water treatment plant showed impacts nearly twice as high as domestic reverse osmosis systems scenario, mainly because of the higher energy inputs. Water treated by domestic reverse osmosis equipment was the most environmentally friendly solution for the improvement of tap water organoleptic characteristics. An economic analysis showed that this solution was between 8 and 19 times cheaper than bottled water.Peer ReviewedPostprint (author's final draft

Revision of the types of species of Alloxysta described by Cameron and Fergusson (Hymenoptera: Figitidae: Charipinae) and deposited in the Natural History Museum (London), including a key to the fauna of Great Britain

Type material of the species of Alloxysta described by Cameron and Fergusson and deposited in the Natural History Museum of London has been revised. Seven species are considered valid: Alloxysta abdera Fergusson, 1986, A. basimacula (Cameron, 1886), A. crassa (Cameron, 1889), A. mullensis (Cameron, 1883), A. piceomaculata (Cameron, 1883), A. pleuralis (Cameron, 1879) and A. semiaperta Fergusson, 1986. A. basimacula, A. crassa, A. maculicollis (Cameron, 1886), A. perplexa (Cameron, 1889) and A. piceomaculata are here removed from synonymy with A. macrophadna (Hartig, 1841). A. rufi ceps (Cameron, 1883) is removed from synonymy with A. victrix (Westwood, 1833). A. caledonica (Cameron, 1886) and A. perplexa are here synonymized with A. basimacula. A. maculicollis, A. ruficeps and A. ruficollis (Cameron, 1883) are here synonymized with A. castanea (Hartig, 1841). A. ancylocera (Cameron, 1886) was correctly synonymized with A. fuscicornis (Hartig, 1841), A. curvicornis (Cameron, 1883) was correctly synonymized with A. victrix and A. filicornis (Cameron, 1889) was correctly synonymized with A. macrophadna. Complete redescriptions and illustrations are given for valid species. A key for all the Alloxysta species found so far in Great Britain is given

Materials ultralleugers: la importància de l’estructura tridimensional

La microxarxa és l’estructura metàl·lica més lleugera que s’ha creat. Amb un 99,99% d’aire, és suficientment lleugera com per sostenir-se sobre un dent de lleó, mentre que la seva estructura la fa resistent. Aquest material, com l’aerografit o l’aerogel de grafè que són fins i tot més lleugers, formen part d’una nova generació de materials ultralleugers que ens permeten observar que les propietats no només depenen d’allò que estan formats els materials, sinó també de la seva estructura 3D. En aquest context, les tècniques de fabricació utilitzades resulten molt importants per al desenvolupament dels nous materials del segle XXI.The microlattice is the lightest metallic structure ever made. At 99.99% air, it’s light enough to balance on top of a dandelion, while its structure makes it strong. This material, such as aerographite or graphene aerogel which are even lighter, are part of a new generation of ultralight materials that allows us to observe that properties do not only depend on what materials are made but also on their 3D structure. In thid context, the manufacturing techniques used are very important for the development of the new materials of the 21st Century