1,011 research outputs found
Good Regulatory Lags for Price Cap and Rolling Cap contracts
Price caps are a popular form of monopoly price regulation. One of its disadvantages is the perverse incentives that regulated firms might have to scamp on cost reducing effort during the last years before a price review. In order to avoid this problem a “rolling cap†contract was introduced in the United Kingdom that overcomes this last problem. In spite of their popularity, there is scant research on the optimal regulatory lag (number of years between price reviews) of a price cap or rolling cap contract. In practice, around the world most price cap or rolling cap contracts have a lag of 4 to 5 years, but this is not based on any optimality consideration. As is well known, the regulatory lag determines the power of an incentive contract and thus the incentives to undertake cost reducing effort. Schmalensee (1989) studied the optimal power of regulatory contracts in a static model with uncertainty and asymmetric information. She finds that medium powered contracts are generally superior to the polar cases of high or low powered contracts. In this paper, we extend Schmalensee (1989) model used to study the optimal power of regulatory contracts to a dynamic framework. We use numerical simulation to study the optimal regulatory lag for different combinations of demand and cost parameters under a particular linear quadratic structure. We find that in general a 2 year lag is optimal under both a price cap and rolling cap contracts and that a benevolent regulator prefers the rolling cap over the price cap contract in almost all the casesPrice Cap, Rolling Cap, Regulatory Lag, Dynamic Programming
Taxonomic studies of the genus Phymaturus (IGUANIA: LIOLAEMIDAE): Description of four new species.
After the study of a diverse collection of Phymaturus from three Argentinian institutions and additional samples collected in the last two years we discovered several populations of uncertain taxonomic status. Based on 93 morphological characters of squamation, color pattern, gular and nuchal folds, precloacal pores, and morphometric data, we conclude that at least four of those are independent lineages which require formal description. Characters related to sexual dimorphism and dichromatism as well as the ontogenetic change of several others, from juvenile to adult specimens, are described. According to the most recent revision of the genus (Lobo and Quinteros, 2005a) and considering the descriptions made in the last four years, the taxonomic composition of the genus was raised to 23 species. In this study we provide the formal description of four additional new taxa, including their diagnosis and detailed comparisons with other members of their species groups. Two new species belong to the patagonicus group (provinces of Chubut and Rio Negro, in Patagonia between 46° and 41° of latitude) while the other two belong to the palluma group (Neuquén and Catamarca provinces, western Argentina, 39° and 27‑26°30’of latitude respectively). With the exception of one case for which four localities are reported, all new species are restricted to their type localities. This fact confirms a common historical distributional pattern for most species of the genusPhymaturus from three Argentinian institutions and additional samples collected in the last two years we discovered several populations of uncertain taxonomic status. Based on 93 morphological characters of squamation, color pattern, gular and nuchal folds, precloacal pores, and morphometric data, we conclude that at least four of those are independent lineages which require formal description. Characters related to sexual dimorphism and dichromatism as well as the ontogenetic change of several others, from juvenile to adult specimens, are described. According to the most recent revision of the genus (Lobo and Quinteros, 2005a) and considering the descriptions made in the last four years, the taxonomic composition of the genus was raised to 23 species. In this study we provide the formal description of four additional new taxa, including their diagnosis and detailed comparisons with other members of their species groups. Two new species belong to the patagonicus group (provinces of Chubut and Rio Negro, in Patagonia between 46° and 41° of latitude) while the other two belong to the palluma group (Neuquén and Catamarca provinces, western Argentina, 39° and 27‑26°30’of latitude respectively). With the exception of one case for which four localities are reported, all new species are restricted to their type localities. This fact confirms a common historical distributional pattern for most species of the genuspatagonicus group (provinces of Chubut and Rio Negro, in Patagonia between 46° and 41° of latitude) while the other two belong to the palluma group (Neuquén and Catamarca provinces, western Argentina, 39° and 27‑26°30’of latitude respectively). With the exception of one case for which four localities are reported, all new species are restricted to their type localities. This fact confirms a common historical distributional pattern for most species of the genuspalluma group (Neuquén and Catamarca provinces, western Argentina, 39° and 27‑26°30’of latitude respectively). With the exception of one case for which four localities are reported, all new species are restricted to their type localities. This fact confirms a common historical distributional pattern for most species of the genus.Fil: Lobo Gaviola, Fernando Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Bio y Geociencias del NOA. Universidad Nacional de Salta. Facultad de Ciencias Naturales. Museo de Ciencias Naturales. Instituto de Bio y Geociencias del NOA; ArgentinaFil: Abdala, Cristian Simón. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - Tucumán. Unidad Ejecutora Lillo; ArgentinaFil: Valdecantos, Maria Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Bio y Geociencias del NOA. Universidad Nacional de Salta. Facultad de Ciencias Naturales. Museo de Ciencias Naturales. Instituto de Bio y Geociencias del NOA; Argentin
The Intelligent Web
Many people are working on the Semantic Web with the main objective being to enhance web searches. Our proposal is a new research strategy based on the existence of a discrete set of semantic relations for the creation and exploitation of semantic networks on the web. To do so, we have defined in a previous paper (Álamo, Martínez, Jaén) the Rhetoric-Semantic Relation (RSR) based on the results of the Rhetoric Structure Theory. We formulate a general set of RSR capable of building discourse and making it possible to express any concept, procedure or principle in terms of knowledge nodes and RSRs. These knowledge nodes can then be elaborated in the same way. This network structure in terms of RSR makes the objective of developing automatic answering systems possible as well as any other type of utilities oriented towards the exploitation of semantic structure, such as the automatic production of web pages or automatic e-learning generation
Didactic Networks and exemplification
After a general overview in a previous paper [AMJ10b], in which we proposed Didactic Networks (DN) as a new way for developing and exploiting web-learning content, we offer here a deeper study showing how to use them for web-learning design and content generation based on Instructional Theory with the coherence guaranty of the RST [MT99]. By using a set of expressivity patterns, it is possible to obtain different final ¿products¿ from the DNs such as different level or different aspect web-learning lessons, depending on the target, documents or evaluation tests. In parallel we are defining the Fundamental Cognitive Networks (FCN), in which we deal with the most common patterns human being uses to think and communicate ideas. This FCN set reuses the representation of Concepts, Procedures and Principles defined here, and it is the main topic of a paper we are working on for the very near future
Didactic Networks: A proposal for e-learning content generation
The Didactic Networks proposed in this paper are based on previous publications in the field of the RSR (Rhetorical-Semantic Relations). The RSR is a set of primitive relations used for building a specific kind of semantic networks for artificial intelligence applications on the web: the RSN (Rhetorical-Semantic Networks). We bring into focus the RSR application in the field of elearning, by defining Didactic Networks as a new set of semantic patterns oriented to the development of eleaming applications. The different lines we offer in our research Jail mainly into three levels: • The most basic one is in the field of computational linguistics and related to Logical Operations on RSR (RSR Inverses and plurals. RSR combinations, etc), once they have been created. The application of Walter Bosma 's results regarding rhetorical distance application and treatment as semantic weighted networks is one of the important issues here. • In parallel, we have been working on the creation of a knowledge representation and storage model and data architecture capable of supporting the definition of knowledge networks based on RSR. • The third strategic line is in the meso-level, the formulation of a molecular structure of knowledge based on the most frequently used patterns. The main contribution at this level is the set of Fundamental Cognitive Networks (FCN) as an application of Novak's mental maps proposal. This paper is part of this third intermediate level, and the Fundamental Didactic Networks (FDN) are the result of the application of rhetorical theoiy procedures to the instructional theory. We have formulated a general set of RSR capable of building discourse, making it possible to express any concept, procedure or principle in terms of knowledge nodes and RSRs. The instructional knowledge can then be elaborated in the same way. This network structure expressing the instructional knowledge in terms of RSR makes the objective of developing web-learning lessons semi-automutkally possible, as well as any other type of utilities oriented towards the exploitation of semantic structure, such as the automatic question answering systems
Una nueva especie de Liolaemus del grupo alticolor (Iguania: Liolaemidae) de la puna salteña, Argentina.
En este trabajo se describe una nueva especie de Liolaemus del grupo alticolor. Liolaemus yanalcu n. sp. se encuentra distribuido en los alrededores del Nevado del Acay en un área aproximada de 400 km2, entre los 3730 y los 4305 m de elevación. Se estudiaron 82 caracteres de lepidosis, patrones de coloración, pliegues, poros precloacales, coloración en vida y modo reproductivo, información que fue utilizada para compararlo con los demás miembros del grupo. La nueva especie presenta coloración general del cuerpo castaño oscura a negra, el campo lateral oscuro y manchas en el mismo casi imperceptibles, carece de manchas paravertebrales, a menudo en los machos la línea vertebral está presente muchas veces fragmentada, patrón de punteado fino intenso en la región ventral de la cola, entre otros. Esta especie cuenta con 10% de hembras con poros precloacales carácter sólo observado en otras dos especies del grupo (L. ramirezae: 94% y L. bitaeniatus: 41%). Fenéticamente la especie más cercana a la nueva especie sería L. ramirezae, habitando un estrato altitudinal inferior a la misma (entre 2820 y 3200 m). Liolaemus yanalcu n. sp. es una forma ovípara, sería la especie de Liolaemus que deposita huevos a mayor altura hasta ahora conocida (3800-4300 m). Este lagarto vive en sintopía con L. albiceps y L. poecilochromus (grupos darwinii y andinus respectivamente) en el área circundante al Acay y con L. irregularis en cercanía de San Antonio de los Cobres.This paper describes a new Liolaemus species of the alticolor group. Populations of Lioalemus yanalcu n. sp. are distributed around the Nevado del Acay over an estimated area of 400 km2, from 3730 to 4305 m above sea level. Eighty two characters including squamation, coloration patterns, skin foldings, precloacal pores, in-life coloration and reproductive mode were studied. This information was used for making comparions with other members of the group. The new species is characterized by having body coloration from dark brown to black, dark lateral field with almost inconspicuous markings, absence of paravertebral markings, vertebral line often presenet (in males) sometimes broken, fine and dense spotted pattern on ventral surface of tail, among other characters. In this species10% of females exhibit precloacal pores (character observed only in L. bitaeniatus, 41% and L. ramirezae, 94%). Phenetically, the closest specuies to the new one is L ramirezae which inhabits a lower altitudinal range (2820-3200 m). Lioalemus yanalcu n. sp is oviparous, and the only oviparous species of Liolaemus living at such high elevation (3800-4300m). This lizard lives sintopically with L. albiceps and L. poecilochromus (darwinii and andinus groups respectively) in surrounding areas of the Nevado del Acay and with L. irregularis near San Antonio de los Cobres.Fil: Martinez Oliver, Inés. Universidad Nacional de Salta; ArgentinaFil: Lobo Gaviola, Fernando Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Bio y Geociencias del NOA. Universidad Nacional de Salta. Facultad de Ciencias Naturales. Museo de Ciencias Naturales. Instituto de Bio y Geociencias del NOA; Argentin
Evolution of form and function in a model of differentiated multicellular organisms with gene regulatory networks
The emergence of novelties, as a generator of diversity, in the form and function of the organisms have long puzzled biologists. The study of the developmental process and the anatomical properties of an organism provides scarce information into the means by which its morphology evolved. Some have argued that the very nature of novelty is believed to be linked to the evolution of gene regulation, rather than to the emergence of new structural genes. In order to gain further insight into the evolution of novelty and diversity, we describe a simple computational model of gene regulation that controls the development of locomotive multicellular organisms through a fixed set of simple structural genes. Organisms, modeled as two-dimensional spring networks, are simulated in a virtual environment to evaluate their steering skills for path-following. Proposed as a behavior-finding problem, this fitness function guides an evolutionary algorithm that produces structures whose function is well-adapted to the environment (i.e., good path-followers). We show that, despite the fixed simple set of structural genes, the evolution of gene regulation yields a rich variety of body plans, including symmetries, body segments, and modularity, resulting in a diversity of original behaviors to follow a simple path. These results suggest that the sole variation in the regulation of gene expression is a sufficient condition for the emergence of novelty and diversity.This work has been partially funded by the Sixth European Union
Framework Program for Research and Technological Development,
contract #028892
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