Price competition under cost uncertainty: A laboratory analysis

We study the relation between the number of firms and price-cost margins under price competition with uncertainty about competitors' costs. We present results of an experiment in which two, three and four identical firms repeatedly interact in this environment. In line with the theoretical prediction, market prices decrease with the number of firms, but on average stay above marginal costs. Pricing is less aggressive in duopolies than in triopolies and tetrapolies. However, independently from the number of firms, pricing is more aggressive than in the theoretical equilibrium. Both the absolute and the relative surpluses increase with the number of firms. Total surplus is close to the equilibrium level, since enhanced consumer surplus through lower prices is counteracted by occasional displacements of the most efficient firm in production.

Comparació de Diagrames UML

El nucli del projecte consisteix en desenvolupar una aplicació permeti determinar si dos models UML són iguals i , en cas de no ser-ho, determinar quines són les diferències entre ells. Donada la gran varietat de models UML, el projecte es centra en els diagrames de classes.

La storia del diritto privato e l’organizzazione giuridica nell’antica Persia

Il sottoscritto lavoro e ricerca è risultato di circa tre anni di ricerche presso l’Università autonoma di Barcellona ed altre università europee ed iraniane. Il tema della ricerca s’intitola “La storia del Diritto Privato e l’organizzazione giuridica nell’antica Persia” ed è stato realizzato con la gentile direzione della Professoressa Gete Alonso, cattedratica di Diritto Civile presso l’Università Autonoma di Barcellona. In questo lavoro si è parlato maggiormente di due dinastie principali dell’era antica persiana ovvero la dinastia degli achemenide ed i sassani , ovvero un periodo di tempo tra l’anno 550 a.c. ed il 651 d.c. in qui fu il culmine dell’evoluzione storica e giuridica iraniana nell’antica Persia che va a sostituirsi con l’attacco e l’invasione araba e l’inizio dell’era islamica. Questo studio ci offre una base adatta ad effettuare di un lato uno studio comparato tra un sistema giuridico mediorientale antico con altri sistemi giuridici vigenti al tempo nel mondo come l’antica Babilinia, Grecia e Roma e d'altronde creare una base per confrontare il diritto antico applicato in Persia con il diritto attuale applicato nella Repubblica Islamica dell’Iran e quindi proporre una base di studio comparato nel tempo e tra vari sistemi giuridici antichi. Spero tanto che questa ricerca possa essere utile agli studiosi interessati a conoscere vari sistemi giuridici per poi confrontarli con altri sistemi antichi ed oggigiorno vigenti in modo tale di poter migliorare giorno dopo giorno le idee giuridiche applicabili nei vari sistemi attuali.

Dynamic higher order expectations

In models where privately informed agents interact, agents may need to formhigher order expectations, i.e. expectations of other agents' expectations. This paper develops a tractable framework for solving and analyzing linear dynamic rational expectationsmodels in which privately informed agents form higher order expectations. The frameworkis used to demonstrate that the well-known problem of the infinite regress of expectationsidentified by Townsend (1983) can be approximated to an arbitrary accuracy with a finitedimensional representation under quite general conditions. The paper is constructive andpresents a fixed point algorithm for finding an accurate solution and provides weak conditions that ensure that a fixed point exists. To help intuition, Singleton's (1987) asset pricingmodel with disparately informed traders is used as a vehicle for the paper.

Tradició misògina grega en el De amore d'Andreu el Capellà

L'objectiu d'aquest article és mostrar com els trets fonamentals de la misogínia grega, que és a la base de la secular misoginia occidental -i que no és només un llegat judeucristià- perviu en un text medieval del segle XIII com ara el De amore d'Andreas Capellanus. L'autor assenyala igualment les vies de transmissió més versemblants des de la Grècia Antiga fins al món medieval.

De Vegetatio notulae, II

161 . Arenarietum viridis. Los inventarios fueron efectuados en la Cova deis Angels, del valle de la Fou (término de la Sénia), en los Ports de Tortosa, a unos 550 m. de altitud.

Emergence of novel domains in proteins

Proteins are composed of a combination of discrete, well-defined, sequence domains, associated with specific functions that have arisen at different times during evolutionary history. The emergence of novel domains is related to protein functional diversification and adaptation. But currently little is known about how novel domains arise and how they subsequently evolve. To gain insights into the impact of recently emerged domains in protein evolution we have identified all human young protein domains that have emerged in approximately the past 550 million years. We have classified them into vertebrate-specific and mammalian-specific groups, and compared them to older domains. We have found 426 different annotated young domains, totalling 995 domain occurrences, which represent about 12.3% of all human domains. We have observed that 61.3% of them arose in newly formed genes, while the remaining 38.7% are found combined with older domains, and have very likely emerged in the context of a previously existing protein. Young domains are preferentially located at the N-terminus of the protein, indicating that, at least in vertebrates, novel functional sequences often emerge there. Furthermore, young domains show significantly higher non-synonymous to synonymous substitution rates than older domains using human and mouse orthologous sequence comparisons. This is also true when we compare young and old domains located in the same protein, suggesting that recently arisen domains tend to evolve in a less constrained manner than older domains. We conclude that proteins tend to gain domains over time, becoming progressively longer. We show that many proteins are made of domains of different age, and that the fastest evolving parts correspond to the domains that have been acquired more recently.

Bienestar social e impuesto sobre la renta

El presente artículo pretende ampliar el modelo original de SANDMO (Journal of Public Economics, 1981 , Vol. 16), relativo a evasión e imposición óptima, en dos direcciones. De un lado, haciendo extensivo el marco de preferencias redistributivas hacia otros objetivos sociales distintos del utilitarista; asimismo, permitiendo el que los sujetos no defraudadores puedan diferir entre sí, de acuerdo con la bibliografía más corriente sobre el tema, por razón de la capacidad productiva que posean en el mercado de trabajo. Dichas modificaciones, además de deslindar los aspectos de aversión al riesgo de lo que propiamente es el grado de concavidad de la función de bienestar, facilitan una más completa descripción del modo como operan los factores que inciden en la conducta del contribuyente.

Hercynian Metamorphism in the Catalonian Coastal Ranges

Paleozoic rocks in the Catalonian Coastal Ranges are in their largestpart affectedby alow-tovery-low grade Hercynian metamorphism. Amphibolite facies conditions are only found in restricted areas such as the southwestern part of the Guilleries massif where upper amphibolite facies conditions are reached. Metamorphic grade increases from top to bottom of the Paleozoic stratigraphic sequence and the metamorphic peak is diachronous, being progressively older in the lower grade metamorphic zones. The isograd pattern, mineral assemblages, mineral chemistry and preserved reaction textures are consistent with a low pressure metamorphism possibly evolving from a previous Barrovian type event. The metamorphic climax in the high grade zone was reached after the seconddeformational phase. Calculatedpeak P-Tconditions are 620-640 OC and around 3.5 Kb . A latter episode of decompression from the maximum conditions to 1-2 Kb, with an associated temperature decrease to 530-550 OC, is recognized. The intrusion of late Hercynian granitoids produced contact metamorphic aureoles where the pyroxene-hornfels facies is locally reached.

Lista actualizada de los opistobranquios (Mollusca: Gastropoda: Opisthobranchia) de las costas catalanas

Se presenta una lista taxonómica de las especies de opistobranquios (Mollusca: Gastropoda: Opisthobranchia) registradas hasta el presente en aguas litorales o de profundidad de las costas catalanas (NE Península Ibérica). Esta lista se basa en citas publicadas en la literatura, en citas fotográficas procedentes de Internet, en comunicaciones personales de buceadores y en numerosos datos inéditos de recolecciones del autor. De cada especie se indican las referencias bibliográficas, y en el caso de los datos no publicados o procedentes de Internet, se indican las localidades concretas donde se han recolectado u observado. En aguas catalanas se registran hasta el momento un total de 205 especies de opistobranquios: 36 de Cephalaspidea s.s., 9 de Architectibranchia, 7 de Anaspidea, 11 de Thecosomata, 3 de Gymnosomata, 14 de Sacoglossa, 2 de Umbraculacea, 8 de Pleurobranchacea y 115 de Nudibranchia (55 Doridina, 14 Dendronotina, 4 Arminina y 42 Aeolidina). De estas especies, tres de ellas se citan por vez primera para el litoral ibérico (Runcina adriatica, R. brenkoae y Tritonia lineata), mientras que otras siete más no habían sido recolectadas en el litoral catalán (Runcina coronata, R. ferruginea, Elysia translucens, Ercolania coerulea, Berthellina edwarsi, Doris ocelligera y Piseinotecus gabinieri). Teniendo en cuenta la extensión del litoral catalán (550 km de costa) y comparando con los datos publicados para otras regiones costeras de la Península Ibérica, se puede concluir que las costas catalanas son muy ricas en biodiversidad de opistobranquios, y que el grado de conocimiento alcanzado sobre este grupo de moluscos es muy alto.

Catalytic gasification of glycerol in supercritical water

The conversion of glycerol in supercritical water (SCW) was studied at 510-550 °C and a pressure of 350 bars using both a bed of inert and non-porous ZrO2 particles (hydrothermal experiments), and a bed of a 1% Ru/ZrO2 catalyst. Experiments were conducted with a glycerol concentration of 5 wt% in a continuous isothermal fixed-bed reactor at a residence time between 2 and 10 s. Hydrothermolysis of glycerol formed water-soluble products such as acetaldehyde, acetic acid, hydroxyacetone and acrolein, and gases like H2, CO and CO2. The catalyst enhanced the formation of acetic acid, inhibited the formation of acrolein, and promoted gasification of the glycerol decomposition products. Hydrogen and carbon oxides were the main gases produced in the catalytic experiments, with minor amounts of methane and ethylene. Complete glycerol conversion was achieved at a residence time of 8.5 s at 510 °C, and at around 5 s at 550 °C with the 1 wt% Ru/ZrO2 catalyst. The catalyst was not active enough to achieve complete gasification since high yields of primary products like acetic acid and acetaldehyde were still present. Carbon balances were between 80 and 60% in the catalytic experiments, decreasing continuously as the residence time was increased. This was attributed partially to the formation of methanol and acetaldehyde, which were not recovered and analyzed efficiently in our set-up, but also to the formation of carbon deposits. Carbon deposition was not observed on the catalyst particles but on the surface of the inert zirconia particles, especially at high residence time. This was related to the higher concentration of acetic acid and other acidic species in the catalytic experiments, which may polymerize to form tar-like carbon precursors. Because of carbon deposition, hydrogen yields were significantly lower than expected; for instance at 550 °C the hydrogen yield potential was only 50% of the stoichiometric value.