Fishing Technology and Optimal Distribution of Harvest Rates

In this paper we analyze the optimal management of a joint ownership fishery exploitation model where agents use different fishing gears. As opposed to other works, we consider a model in which the fishing technology affects resource's growth not only through the harvest function, but also through the natural growth rate of the resource. The main objective is to capture the evidence that some fishing gears alter the habitat of the resource, and may alter the natural growth rate of the resource. The main result we obtain is that, when the natural growth of the resource is altered by the fishing technology, the optimal stock is not independent of how harvest quotas are distributed among the agents. Thus, in this context, a fishing policy that determines, first, the optimum stock and, secondly, decides on how to distribute the harvest among the different agents will not be efficient.fisheries regulation, fishing gear's selectivity, sharing of quotas

International and Intergenerational Dimensions of Climate Change: North-South Cooperation in an Overlapping Generations Framework

Global environmental problems such as climate change have both an international and an intertemporal dimension. Recently, some papers have used an overlapping generations framework to analyze the climate change problem taking into account jointly the issues of intergenerational equity and intertemporal efficiency but without considering the international aspect of the problem. In this paper, we extend such approach by considering an overlapping generations model of climate-economy interactions where the world is split into two regions: North and South. We resort to numerical simulations of the calibrated model to analyze the effect of cooperation over economic and climate variables under two different scenarios: long-lived and short-lived governments. The main aim of our analysis is to test numrically whether John and Pecchenino´s (1997) theoretical result, which states that international agreements with transfers that lack an intergenerational perspective could actually harm the environment, applies low us to conclude that when we consider short lived governments: (1) the lack of cooperation always leads to higher environmental degradation, (2) the higher the welfare weight attached to the North under cooperation, the lower the environmental degradation in the long run, and (3) some cooperative scenarios may lead in the short run to higher environmental degradation than what it would arise in the non cooperative scenario.international environmental agreements, intergenerational externality, climate change

Evolution and relationships of the conifer seed cone telemachus: Evidence from the triassic of antarctica

The seed cone Telemachus is known from several Triassic localities in Gondwana. New specimens from two localities in Antarctica provide additional information about the type species, Telemachus elongatus, based on details of morphology and anatomy revealed by using a modified transfer technique on the compressed plants. Seed cones of T. elongatus are up to 6.0 cm long and characterized by conspicuous, elongate bracts. A second Antarctic species, described here as Telemachus antarcticus, is segregated, based on a shorter bract and differences in cone size. Newly recognized features of the genus include the shape, size, and disposition of the ovules; vascularization of the ovuliferous complex; and scale and bract histology. As a result of this new information, it is now possible to compare Telemachus with the permineralized Middle Triassic conifer seed cone Parasciadopitys from the Central Transantarctic Mountains. The similarities between the two genera make it possible to relate organs in different preservational modes and to develop a more complete concept for this widely distributed Gondwana conifer. Placing the Telemachus plant within a phylogenetic context makes it possible to evaluate the relationship with other so-called transitional conifers, an informal group that has been interpreted as intermediate between Paleozoic and modern conifers.Fil: Escapa, Ignacio Hernán. University of Kansas; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Decombeix, Anne-Laure. University of Kansas; Estados UnidosFil: Taylor, Edith L.. University of Kansas; Estados UnidosFil: Taylor, Thomas N.. University of Kansas; Estados Unido

Mares sobrecarregades. Factors que causen més dedicació de les mares en el treball domèstic

Utilitzant dades d'una mostra de 1.926 famílies formades per tots dos progenitors (pare i mare) i almenys un fill, s'ha examinat la relació que hi ha entre les característiques familiars (recursos, disponibilitat de temps, factors sociodemogràfics, característiques de les parelles i individuals) i les càrregues domèstiques de les mares a Catalunya. Aquesta mostra s'ha analitzat mitjançant regressions logístiques, per tal de trobar els perfils de les mares que són més propenses a dedicar una gran quantitat d'hores fent les tasques de la llar. A partir d'investigacions prèvies, s'hi plantegen diferents elements explicatius: la disponibilitat de temps, els recursos relatius, la situació professional i la influència de la participació domèstica de la parella. Els resultats confirmen una relació significativa entre els recursos relatius i la disponibilitat de temps de la mare pel que fa a la seva dedicació a la llar, la qual cosa dóna suport a les perspectives econòmiques de la distribució de les tasques de la llar i de la ideologia tradicional dels rols de gènere. No obstant això, els resultats també mostren que la presència d'homes cooperatius no només no implica una reducció de la jornada domèstica de les seves parelles, sinó que també augmenta la probabilitat d'una dedicació més gran de les mares. Això es deu al fet que la distribució de les tasques domèstiques en algunes llars respon més a una estratègia parental comuna, basada en la inversió de temps a la llar i en les relacions intergeneracionals, que no pas a una negociació basada en «el que faci l'un no cal que ho faci l'altre»

From The Big Apple To Big Ben: An Insight Into Menu Labeling

Imagine looking around and recognizing that you are much heavier than your fellow peers

Solidaridad intergeneracional en época de crisis: ¿Mito o realidad?

La prolongación de la crisis económica ha multiplicado el interés por conocer los mecanismos que amortiguan las consecuencias de las situaciones de privación. Un relato extendido atribuye un papel central a los abuelos y abuelas que están acudiendo a socorrer con sus pensiones a sus hijos y nietos. Sin embargo, las evidencias de que disponemos sobre cambios en las estructuras y flujos de solidaridad intergeneracional son más bien escasas. El artículo explora la magnitud y naturaleza de las ayudas entre padres, madres, abuelos y abuelas, por un lado, e hijos, hijas, nietos y nietas, por otro, en España comparativamente a otros países europeos, centrándose en la corresidencia, el cuidado de nietos y las transferencias económicas inter vivos

Fertile osmundaceae from the early Jurassic of patagonia, Argentina

Two new compression-impression species of the Osmundaceae described from reproductive and vegetative remains are erected for the first time from the Early Jurassic of Argentina. Todites cacereii sp. nov. and Osmundopsis rafaelii sp. nov. demonstrate that two main osmundaceous reproductive morphologies; i.e., differentiated reduced or unreduced fertile laminae were already present and widespread in Gondwana by this time. On the basis of a discussion of relevant morphological characters, the phylogenetic meaning of the fossils Todites and Osmundopsis is explored. Likewise, the systematics and taxonomy of fossil taxa and their relationships with modern ones are discussed in light of current hypotheses. In this regard, because clear synapomorphies or apomorphies are not yet fully understood, it is suggested that fossil representatives are better placed in morphotaxa (Todites, Osmundopsis) than in any current genus. Nonetheless, the clear record of characters of the leptopteroid clade by the early Jurassic proves to be older than previously assumed, which also points to an earlier time of origination for the osmundaceous ferns.Fil: Escapa, Ignacio Hernán. Museo Paleontológico Egidio Feruglio; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Cúneo, Néstor Rubén. Museo Paleontológico Egidio Feruglio; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Microbial electromethanogenesis for energy storage: Influence of acidic pH on process performance

[EN] Microbial electromethanogenesis (EM) has positioned itself as a promising technology for electrical energy storage using CO2 as a feedstock. However, the selectivity of the final product remains a challenge, being highly dependent of the operating conditions (temperature, pH, conductivity, etc.). This study tries to understand the role that pH plays on the start-up, performance and the structure of microbial communities of an EM system. To that end, two EM reactors were started at pH 7.0 and 5.5 respectively and were subsequently subjected to pH variations between 7.5 and 3.5. The reactor inoculated at pH 5.5 started to produce CH4 earlier than that inoculated at pH 7.0, and the acetogenic activity was gradually displaced by methanogenesis during the start-up period, regardless of the pH. In addition, as the pH of the catholyte became more acidic, the performance improved in terms of methane production, current density and columbic efficiency. Acidic environments – pH around 4.5 – promoted higher methane production due to the selection of Methanobacterium, an acid-tolerant hydrogenotrophic archaea. When pH was set at 3.5, the overall performance declined sharply, probably because it induced unfavourable physiological conditions.SIMinisterio de Ciencia e Innovació