Learning from errors

We present a model of learning in which agents learn from errors. If an action turns out to be an error, the agent rejects not only that action but also neighboring actions. We find that, keepng memory of his errors, under mild assumptions an acceptable solution is asymptotically reached. Moreover, one can take advantage of big errors for a faster learning.

How universal is behavior? A four country comparison of spite, cooperation and errors in voluntary contribution mechanisms

This paper studies behavior in experiments with a linear voluntary contributions mechanism for public goods conducted in Japan, the Netherlands, Spain and the USA. The same experimental design was used in the four countries. Our 'contribution function' design allows us to obtain a view of subjects' behavior from two complementary points of view. If yields information about situations where, in purely pecuniary terms, it is a dominant strategy to contribute all the endowment and about situations where it is a dominant strategy to contribute nothing. Our results show, first, that differences in behavior across countries are minor. We find that when people play "the same game" they behave similarly. Second, for all four countries our data are inconsistent with the explanation that subjects contribute only out of confusion. A common cooperative motivation is needed to explain the date.

Errors sintàctics del gènere gramatical durant la cirurgia de gliomes cerebrals

Les bases neurals del processament sintàctic del gènere no han estat gairebé estudiades. En aquest estudi hem utilitzat el mapeig cerebral, durant la cirurgia de gliomes cerebrals per a estudiar les estructures cortico-subcorticals implicades en el processament del gènere i determinar si aquestes són comunes a altres àrees de la producció del llenguatge. Amb l’estimulació cerebral directa hem observat alteracions sintàctiques del gènere, al estimular la circumvolució frontal inferior, la part posterior circumvolució temporal mitja, i en el nucli caudat. També hem pogut observar, una doble dissociació entre el gènere gramatical i la producció de la paraula, corroborant les teories d’un model independent en la producció del llenguatge.

Driving competition in local gasoline markets

Relevant market definition is still a key element of economic analysis of competition in the gasoline market. It is particularly difficult to handle when competition is local and market power is geographically constrained like is the case in the gasoline market. We analyse how the application of the hypothetical monopolist or Small but Significant Non-Transitory Increase in Prices (SSNIP) test performs for defining isochrones using only information on prices and distance among competitors. We conclude that geographic information systems can be very successfully used to define more precisely relevant geographic market in the gasoline retailing. The application to the Spanish gasoline market concludes that geographic relevant market is composed by 5-6 minutes of travel time. Localised market power should be taken into account when analysing the adverse effects of mergers and entry regulations in gasoline retailing. Only drawing small enough isochrones will drive competition in local markets because it is just close rivals that compete effectively with each other.

Estratègies i errors en la resolució de problemes d'extrems per mètodes elementals

Aquesta investigació s’engloba dins del camp de la resolució de problemes en educació matemàtica i se centra en estudiar de quina manera els alumnes de primer curs de Batxillerat de dos instituts públics de Catalunya resolen alguns problemes d’extrems per mètodes elementals, és a dir, sense utilitzar les tècniques del càlcul diferencial. Tanmateix, s’estudia el punt de partida d’aquests alumnes davant dels problemes de màxims i mínims i es detecten algunes estratègies i diversos errors que cometen a l’hora de resoldre’ls. L’instrument de recollida de dades és un qüestionari individual que combina problemes d’extrems de resposta tancada amb altres problemes de resposta oberta. Es realitza una anàlisi inductiva – deductiva de les dades, la qual permet determinar que una part important dels participants en la recerca confonen les relacions entre l’àrea i el volum d’algunes figures geomètriques. A més, la majoria dels alumnes d’aquesta investigació resolen els problemes d’extrems plantejats fent ús de l’estratègia de conjecturar. Finalment, es detecta que diverses respostes dels participants presenten errors causats per l’ús de teoremes i/o de definicions matemàtiques equivocades. Aquest és el cas d’una aplicació errònia del teorema de Pitàgores, la confusió del perímetre d’un quadrat amb la longitud del seu costat i la determinació incorrecta de l’altura de diversos paral·lelograms.

Fusion of data sets in multivariate linear regression with errors-in-variables

We consider the application of normal theory methods to the estimation and testing of a general type of multivariate regressionmodels with errors--in--variables, in the case where various data setsare merged into a single analysis and the observable variables deviatepossibly from normality. The various samples to be merged can differ on the set of observable variables available. We show that there is a convenient way to parameterize the model so that, despite the possiblenon--normality of the data, normal--theory methods yield correct inferencesfor the parameters of interest and for the goodness--of--fit test. Thetheory described encompasses both the functional and structural modelcases, and can be implemented using standard software for structuralequations models, such as LISREL, EQS, LISCOMP, among others. An illustration with Monte Carlo data is presented.

Award errors and permanent disability benefits in Spain

There is a controversial debate about the effects of permanent disability benefits on labormarket behavior. In this paper we estimate equations for deserving and receiving disabilitybenefits to evaluate the award error as the difference in the probability of receiving anddeserving using survey data from Spain. Our results indicate that individuals aged between55 and 59, self-employers or working in an agricultural sector have a probability of receiving a benefit without deserving it significantly higher than the rest of individuals. We also find evidence of gender discrimination since male have a significantly higher probability of receiving a benefit without deserving it. This seems to confirm that disability benefits are being used as an instrument for exiting the labor market for some individuals approaching the early retirement or those who do not have right to retire early. Taking into account that awarding process depends on Social Security Provincial Department, this means that some departments are applying loosely the disability requirements for granting disability benefits.

Fine-Tuning Translation Kinetics Selection as the Driving Force of Codon Usage Bias in the Hepatitis A Virus Capsid

Hepatitis A virus (HAV), the prototype of genus Hepatovirus, has several unique biological characteristics that distinguish it from other members of the Picornaviridae family. Among these, the need for an intact eIF4G factor for the initiation of translation results in an inability to shut down host protein synthesis by a mechanism similar to that of other picornaviruses. Consequently, HAV must inefficiently compete for the cellular translational machinery and this may explain its poor growth in cell culture. In this context of virus/cell competition, HAV has strategically adopted a naturally highly deoptimized codon usage with respect to that of its cellular host. With the aim to optimize its codon usage the virus was adapted to propagate in cells with impaired protein synthesis, in order to make tRNA pools more available for the virus. A significant loss of fitness was the immediate response to the adaptation process that was, however, later on recovered and more associated to a re-deoptimization rather than to an optimization of the codon usage specifically in the capsid coding region. These results exclude translation selection and instead suggest fine-tuning translation kinetics selection as the underlying mechanism of the codon usage bias in this specific genome region. Additionally, the results provide clear evidence of the Red Queen dynamics of evolution since the virus has very much evolved to re-adapt its codon usage to the environmental cellular changing conditions in order to recover the original fitness.

Els errors en les relacions assistencials: una aproximació des de la bioètica

De manera general, cal tenir present quel'error és habitual en els sistemes complexos, com la biologia ens ho ensenya ja a nivell cel·lular: els errors en la replicació de l'ADN els anomenem mutacions i pel que sabem han jugat i juguen un rol fonamental en l'evolució de les espècies vivents. L'error, per tant, és omnipresenten els organismes vivents; però, a diferènciade les màquines artificials, els organismesvivents poden funcionar amb l¿error i malgratl¿error.

Errors congènits del metabolisme (ECM).

La terminologia i el concepte d'Error Congènit del Metabolisme (ECM), van ser establerts per A. Garrod a principis de segle. Avui día sabem que estan causats per errors o mutacions en els gens. Degut a la naturalesa del nostre codi genètic, segons el qual les instruccions del DNA són traduïdes a un producte gènic, les proteïnes, que seran les encarregades d'executar-lo; les mutacions del DNA es tradueixen en proteïnes anòmales amb la corresponent...

Spectrum of transmitted light in optical bistability: Effects of phase fluctuations of the driving laser

Time-dependent correlation functions and the spectrum of the transmitted light are calculated for absorptive optical bistability taking into account phase fluctuations of the driving laser. These fluctuations are modeled by an extended phase-diffusion model which introduces non-Markovian effects. The spectrum is obtained as a superposition of Lorentzians. It shows qualitative differences with respect to the usual calculation in which phase fluctuations of the driving laser are neglected.

Influence of the driving mechanism on the response of systems with athermal dynamics: The example of the random-field Ising model

We investigate the influence of the driving mechanism on the hysteretic response of systems with athermal dynamics. In the framework of local mean-field theory at finite temperature (but neglecting thermally activated processes), we compare the rate-independent hysteresis loops obtained in the random field Ising model when controlling either the external magnetic field H or the extensive magnetization M. Two distinct behaviors are observed, depending on disorder strength. At large disorder, the H-driven and M-driven protocols yield identical hysteresis loops in the thermodynamic limit. At low disorder, when the H-driven magnetization curve is discontinuous (due to the presence of a macroscopic avalanche), the M-driven loop is reentrant while the induced field exhibits strong intermittent fluctuations and is only weakly self-averaging. The relevance of these results to the experimental observations in ferromagnetic materials, shape memory alloys, and other disordered systems is discussed.

Driving rate effects in avalanche-mediated first-order phase transitions

We study the driving-rate and temperature dependence of the power-law exponents that characterize the avalanche distribution in first-order phase transitions. Measurements of acoustic emission in structural transitions in Cu-Zn-Al and Cu-Al-Ni are presented. We show how the observed behavior emerges within a general framework of competing time scales of avalanche relaxation, driving rate, and thermal fluctuations. We confirm our findings by numerical simulations of a prototype model.

Fine-Tuning Translation Kinetics Selection as the Driving Force of Codon Usage Bias in the Hepatitis A Virus Capsid

Hepatitis A virus (HAV), the prototype of genus Hepatovirus, has several unique biological characteristics that distinguish it from other members of the Picornaviridae family. Among these, the need for an intact eIF4G factor for the initiation of translation results in an inability to shut down host protein synthesis by a mechanism similar to that of other picornaviruses. Consequently, HAV must inefficiently compete for the cellular translational machinery and this may explain its poor growth in cell culture. In this context of virus/cell competition, HAV has strategically adopted a naturally highly deoptimized codon usage with respect to that of its cellular host. With the aim to optimize its codon usage the virus was adapted to propagate in cells with impaired protein synthesis, in order to make tRNA pools more available for the virus. A significant loss of fitness was the immediate response to the adaptation process that was, however, later on recovered and more associated to a re-deoptimization rather than to an optimization of the codon usage specifically in the capsid coding region. These results exclude translation selection and instead suggest fine-tuning translation kinetics selection as the underlying mechanism of the codon usage bias in this specific genome region. Additionally, the results provide clear evidence of the Red Queen dynamics of evolution since the virus has very much evolved to re-adapt its codon usage to the environmental cellular changing conditions in order to recover the original fitness.

Estudi comparatiu: errors de les infermeres en la preparació i l'administració de la medicació segons dos sistemes de distribució

Introducció: Els errors de medicació són definits com qualsevol incident prevenible que pot causar dany al pacient o donar lloc a una utilització inapropiada dels medicaments, quan aquests estan sota el control dels professionals sanitaris o del pacient. Els errors en la preparació i l’administració de medicació són els més comuns de l’àrea hospitalària i, tot i la llarga cadena per la qual passa el fàrmac, el professional d’infermeria és el últim responsable de l’acció, tenint així, un paper molt important en la seguretat del pacient. Les infermeres dediquen el 40% del temps de la seva jornada laboral en tasques relacionades amb la medicació. Objectiu: Determinar si les infermeres produeixen més errors si treballen amb sistemes de distribució de medicació de stock o en sistemes de distribució unidosis de medicació. Metodologia: Estudi quantitatiu, observacional i descriptiu, on la notificació d’errors (o oportunitats d’error) realitzats per la infermera, en les fases de preparació i administració de medicació, es farà mitjançant un qüestionari autoelaborat. Els elements a identificar seran: el tipus d’error, les causes que poden haver--‐lo produït, la seva potencial gravetat i qui l’ha pogut evitar; així com el tipus de professional que l’ha produït. Altres dades rellevants són: el medicament implicat junt amb la dosis i la via d’administració i el sistema de distribució utilitzat. Mostreig i mostra: El mostreig serà no probabilístic i per conveniència. S’escolliran aquelles infermeres que l’investigador consideri amb les característiques necessàries per participar en l’estudi, així que la mostra estarà formada per les infermeres les quals treballen a la unitat 40 de l’Hospital del Mar i utilitzen un sistema de distribució de medicació de dosis unitàries i les infermeres que treballen a urgències (concretament a l’àrea de nivell dos) de l’Hospital del Mar les quals treballen amb un sistema de distribució de medicació de stock.