Phenotypic variability of retinocytomas: preregression and postregression growth patterns.

AIM: To describe the incidence of retinocytomas, their variability at presentation and their growth patterns both before and after regression.¦METHODS: Medical notes of the 525 patients of the Jules-Gonin Eye Hospital Retinoblastoma Clinic between 1964 and 2008 were reviewed and the charts of 36 patients with retinocytomas and/or phthisis bulbi were selected.¦RESULTS: The proportion of patients with retinocytomas and/or phthisis bulbi was 3.2%. The mean age at diagnosis was 28.7±17 years. Five tumours presented a cystic pattern (5.8%). Evidence of aggressive exophytic disease prior to spontaneous regression was documented in two eyes, and of invasive endophytic disease (regressed vitreous seeding or internal limiting membrane disruption) in three eyes. Twenty patients were followed with a mean follow-up of 44±60 months. Tumour growth was observed in 16% cases, benign cystic enlargement in 4% and malignant transformation in 12%.¦CONCLUSION: This large study of retinocytomas substantially expands the published features of retinocytoma by describing the cystic nature of some retinocytomas as well as clinical characteristics of the endophytic and exophytic preregression growth patterns. The authors report two different patterns of reactivation: benign cystic enlargement and malignant transformation with or without cystic growth. Higher than previously reported frequency of growth and possible life-threatening complications impose close lifetime follow-up of retinocytoma patients.

Topographic organization of V1 projections through the corpus callosum in humans.

The visual cortex in each hemisphere is linked to the opposite hemisphere by axonal projections that pass through the splenium of the corpus callosum. Visual-callosal connections in humans and macaques are found along the V1/V2 border where the vertical meridian is represented. Here we identify the topography of V1 vertical midline projections through the splenium within six human subjects with normal vision using diffusion-weighted MR imaging and probabilistic diffusion tractography. Tractography seed points within the splenium were classified according to their estimated connectivity profiles to topographic subregions of V1, as defined by functional retinotopic mapping. First, we report a ventral-dorsal mapping within the splenium with fibers from ventral V1 (representing the upper visual field) projecting to the inferior-anterior corner of the splenium and fibers from dorsal V1 (representing the lower visual field) projecting to the superior-posterior end. Second, we also report an eccentricity gradient of projections from foveal-to-peripheral V1 subregions running in the anterior-superior to posterior-inferior direction, orthogonal to the dorsal-ventral mapping. These results confirm and add to a previous diffusion MRI study (Dougherty et al., 2005) which identified a dorsal/ventral mapping of human splenial fibers. These findings yield a more detailed view of the structural organization of the splenium than previously reported and offer new opportunities to study structural plasticity in the visual system.

¿Es posible reducir el gasto sanitario a través del subsidio a los seguros sanitarios privados? La doble cobertura sanitaria en Catalunya. Estimación de patrones de utilización de servicios sanitarios y simulación de costes asociados a la asistencia

The objective of this study consists in quantifying in money terms thepotential reduction in usage of public health care outlets associatedto the tenure of double (public plus private) insurance. In order to address the problem, a probabilistic model for visits to physicians is specified and estimated using data from the Catalonian Health Survey. Also, a model for the marginal cost of a visit to a physician is estimated using data from a representative sample of fee-for-service payments from a major insurer. Combining the estimates from the two models it is possible to quantify in money terms the cost/savings of alternative policies which bear an impact on the adoption of double insurance by the population. The results suggest that the private sector absorbs an important volumeof demand which would be re-directed to the public sector if consumerscease to hold double insurance.

Efficient interval scoring rules

Scoring rules that elicit an entire belief distribution through the elicitation of point beliefsare time-consuming and demand considerable cognitive e¤ort. Moreover, the results are validonly when agents are risk-neutral or when one uses probabilistic rules. We investigate a classof rules in which the agent has to choose an interval and is rewarded (deterministically) onthe basis of the chosen interval and the realization of the random variable. We formulatean e¢ ciency criterion for such rules and present a speci.c interval scoring rule. For single-peaked beliefs, our rule gives information about both the location and the dispersion of thebelief distribution. These results hold for all concave utility functions.

Effective Shoulder Design and Maintenance, 2007

Granular shoulders are an important element of the transportation system and are constantly subjected to performance problems due to wind- and water-induced erosion, rutting, edge drop-off, and slope irregularities. Such problems can directly affect drivers’ safety and often require regular maintenance. The present research study was undertaken to investigate the factors contributing to these performance problems and to propose new ideas to design and maintain granular shoulders while keeping ownership costs low. This report includes observations made during a field reconnaissance study, findings from an effort to stabilize the granular and subgrade layer at six shoulder test sections, and the results of a laboratory box study where a shoulder section overlying a soft foundation layer was simulated. Based on the research described in this report, the following changes are proposed to the construction and maintenance methods for granular shoulders: • A minimum CBR value for the granular and subgrade layer should be selected to alleviate edge drop-off and rutting formation. • For those constructing new shoulder sections, the design charts provided in this report can be used as a rapid guide based on an allowable rut depth. The charts can also be used to predict the behavior of existing shoulders. • In the case of existing shoulder sections overlying soft foundations, the use of geogrid or fly ash stabilization proved to be an effective technique for mitigating shoulder rutting.

Mapping of Environmental Data Using Kernel-Based Methods

Recently, kernel-based Machine Learning methods have gained great popularity in many data analysis and data mining fields: pattern recognition, biocomputing, speech and vision, engineering, remote sensing etc. The paper describes the use of kernel methods to approach the processing of large datasets from environmental monitoring networks. Several typical problems of the environmental sciences and their solutions provided by kernel-based methods are considered: classification of categorical data (soil type classification), mapping of environmental and pollution continuous information (pollution of soil by radionuclides), mapping with auxiliary information (climatic data from Aral Sea region). The promising developments, such as automatic emergency hot spot detection and monitoring network optimization are discussed as well.

Additional utility of insiders with imperfect dynamical information

In this paper we consider an insider with privileged information thatis affected by an independent noise vanishing as the revelation timeapproaches. At this time, information is available to every trader. Ourfinancial markets are based on Wiener space. In probabilistic terms weobtain an infinite dimensional extension of Jacod s theorem to covercases of progressive enlargement of filtrations. The application ofthis result gives the semimartingale decomposition of the originalWiener process under the progressively enlarged filtration. As anapplication we prove that if the rate at which the additional noise inthe insider s information vanishes is slow enough then there is noarbitrage and the additional utility of the insider is finite.

Measuring strategic uncertainty in coordination games

This paper explores three aspects of strategic uncertainty: its relation to risk, predictability of behavior and subjective beliefs of players. In a laboratory experiment we measure subjects certainty equivalents for three coordination games and one lottery. Behavior in coordination games is related to risk aversion, experience seeking, and age.From the distribution of certainty equivalents we estimate probabilities for successful coordination in a wide range of games. For many games, success of coordination is predictable with a reasonable error rate. The best response to observed behavior is close to the global-game solution. Comparing choices in coordination games with revealed risk aversion, we estimate subjective probabilities for successful coordination. In games with a low coordination requirement, most subjects underestimate the probability of success. In games with a high coordination requirement, most subjects overestimate this probability. Estimating probabilistic decision models, we show that the quality of predictions can be improved when individual characteristics are taken into account. Subjects behavior is consistent with probabilistic beliefs about the aggregate outcome, but inconsistent with probabilistic beliefs about individual behavior.

Econometrics and decision making: Effects of presentation mode

Much of empirical economics involves regression analysis. However, does thepresentation of results affect economists ability to make inferences for decision makingpurposes? In a survey, 257 academic economists were asked to make probabilisticinferences on the basis of the outputs of a regression analysis presented in a standardformat. Questions concerned the distribution of the dependent variable conditional onknown values of the independent variable. However, many respondents underestimateduncertainty by failing to take into account the standard deviation of the estimatedresiduals. The addition of graphs did not substantially improve inferences. On the otherhand, when only graphs were provided (i.e., with no statistics), respondents weresubstantially more accurate. We discuss implications for improving practice in reportingresults of regression analyses.

Experiencing simulated outcomes

Whereas much literature has documented difficulties in making probabilistic inferences, it hasalso emphasized the importance of task characteristics in determining judgmental accuracy.Noting that people exhibit remarkable efficiency in encoding frequency information sequentially,we construct tasks that exploit this ability by requiring people to experience the outcomes ofsequentially simulated data. We report two experiments. The first involved seven well-knownprobabilistic inference tasks. Participants differed in statistical sophistication and answered withand without experience obtained through sequentially simulated outcomes in a design thatpermitted both between- and within-subject analyses. The second experiment involvedinterpreting the outcomes of a regression analysis when making inferences for investmentdecisions. In both experiments, even the statistically naïve make accurate probabilistic inferencesafter experiencing sequentially simulated outcomes and many prefer this presentation format. Weconclude by discussing theoretical and practical implications.

Multiple prisoner's dilemma games with (out) an outside option: An experimental study

Experiments in which subjects play simultaneously several finite prisoner's dilemma supergames with and without an outside optionreveal that: (i) subjects use probabilistic start and endeffect behaviour, (ii) the freedom to choose whether to play the prisoner's dilemma game enhances cooperation, (iii) if the payoff for simultaneous defection is negative, subjects' tendency to avoid losses leads them to cooperate; while this tendency makes them stick to mutual defection if its payoff is positive.

Cumulative dominance and heuristic performance in binary multi-attribute choice

Several studies have reported high performance of simple decision heuristics multi-attribute decision making. In this paper, we focus on situations where attributes are binary and analyze the performance of Deterministic-Elimination-By-Aspects (DEBA) and similar decision heuristics. We consider non-increasing weights and two probabilistic models for the attribute values: one where attribute values are independent Bernoulli randomvariables; the other one where they are binary random variables with inter-attribute positive correlations. Using these models, we show that good performance of DEBA is explained by the presence of cumulative as opposed to simple dominance. We therefore introduce the concepts of cumulative dominance compliance and fully cumulative dominance compliance and show that DEBA satisfies those properties. We derive a lower bound with which cumulative dominance compliant heuristics will choose a best alternative and show that, even with many attributes, this is not small. We also derive an upper bound for the expected loss of fully cumulative compliance heuristics and show that this is moderateeven when the number of attributes is large. Both bounds are independent of the values ofthe weights.

Why England? Demand, growth and inequality during the Industrial Revolution

Why was England first? And why Europe? We present a probabilistic model that builds on big-push models by Murphy, Shleifer and Vishny (1989), combined with hierarchical preferences. The interaction of exogenous demographic factors (in particular the English low-pressure variant of the European marriage pattern)and redistributive institutions such as the old Poor Law combined to make an Industrial Revolution more likely. Essentially, industrialization is the result of having a critical mass of consumers that is rich enough to afford (potentially) mass-produced goods. Our model is then calibrated to match the main characteristics of the English economy in 1750 and the observed transition until 1850.This allows us to address explicitly one of the key features of the British IndustrialRevolution unearthed by economic historians over the last three decades the slowness of productivity and output change. In our calibration, we find that the probability of Britain industrializing is 5 times larger than France s. Contrary to the recent argument by Pomeranz, China in the 18th century had essentially no chance to industrialize at all. This difference is decomposed into a demographic and a policy component, with the former being far more important than the latter.

O efeito do sorriso na percepção psicológica da pessoa

O objectivo do estudo foi o de verificar o efeito do sorriso na percepção psicológica da pessoa em jovens, adultos, idosos e jovens negros. Pretendia-se verificar se o sorriso contribui para os traços diferenciais entre os grupos humanos em estudo e se o mesmo era descritor de género. O estudo envolveu um delineamento transversal analítico ou estudo não-experimental, também classificado por estudo pós-facto, estudo de observação passiva ou estudo correlacional e de observação, de comparação entre grupos, mediante o juízo ou julgamento psicológico da face neutra e do tipo de sorriso contrastados, de matriz factorial 4 x 2 x 2 (face neutra, sorriso fechado, sorriso superior, sorriso largo; género dos estímulos; género dos respondentes) e a sua finalidade foi descrever a percepção psicológica do sorriso em função das variáveis género do estímulo, género do respondente e grupo étnico, na Escala de Percepção do Sorriso (EPS), em formato diferenciador semântico, com 19 itens bipolares opostos, tendo a avaliação sido feita numa escala ordinal de 1 a 7 pontos, nas dimensões Avaliação (12 itens) e Movimento Expressivo (7 itens) resultante dos estudos preliminares sobre a atractividade facial (estudo preliminar 1) e a escolha de dípolos de adjectivos preditores para percepção psicológica da face neutra (estudo preliminar 2). Nos estudos principais 1, 2 e 3 foram utilizados 24 estímulos fotográficos apresentando o tipo de sorriso (fechado, superior e largo) e a face neutra (12 do estímulo mulher e 12 do estímulo homem) referentes aos três grupos etários (18-25 anos, 40-50 anos e 60-70 anos) e a Escala de Percepção do Sorriso (EPS) foi aplicada a uma amostra não probabilística ou intencional do tipo homogénea de 480 participantes portugueses de ambos os géneros (240 mulheres e 240 homens) distribuídos por grupos etários de jovens (80 mulheres e 80 homens, média: 22.2 anos), adultos (80 mulheres e 80 homens, média: 43.1 anos) e idosos (80 mulheres e 80 homens, média: 65.0 anos) No estudo principal 4, foram utilizados 8 estímulos fotográficos apresentando o tipo de sorriso (fechado, superior e largo) e a face neutra (4 do estímulo mulher e 4 do estímulo homem) de universitários de Cabo Verde, a estudar em Portugal, e a Escala de Percepção do Sorriso (EPS) foi aplicada a uma amostra não probabilística ou intencional do tipo homogénea de 160 participantes de ambos os géneros (80 mulheres e 80 homens) e estudantes universitários portugueses (média: 21.8 anos). Os resultados revelam e confirmam o efeito do sorriso na percepção psicológica da pessoa, à semelhança de outros estudos, isto é, sorrir torna a percepção psicológica mais positiva ou negativa e verifica-se que tal sucede em função do género do estímulo e do género do respondente. As diferenças significativas na percepção da face neutra e tipo de sorriso contrastados são justificadas pela pertença de género de quem os percepciona e pela pertença do género de quem é percepcionado. Tal apenas não sucede no factor Avaliação do grupo dos adultos. Os resultados obtidos indicam que, quer no factor Avaliação quer no factor Movimento Expressivo, os tipos de sorriso largo e superior são os que registam médias ponderadas mais elevadas. Pelo contrário, a face neutra e o sorriso fechado registam valores menos elevados na percepção. A análise da percepção da pessoa em função da face neutra e tipo de sorriso contrastados revelou uma correspondência entre a expressão facial, o género do estímulo e o género do respondente. No factor Avaliação, a mulher é percepcionada mais positivamente que o homem, verificando-se o inverso no factor Movimento Expressivo no grupo dos adultos e dos idosos. Verificou-se efeito do sorriso na percepção psicológica dos estímulos de cor negra. No grupo dos jovens que percepcionaram estímulos de cor negra, o homem é considerado mais positivo que a mulher em ambos os factores. O efeito significativo do género revela que a sua percepção é condicionada pelo seu próprio género. Os resultados apontam ainda para a configuração pronunciada de uma hierarquização ascendente da face neutra e tipo de sorriso contrastados em dois conjuntos bem delimitados e distinguindo diferentes formas topográficas de sorrir: a face neutra e o sorriso fechado e o sorriso superior e o sorriso largo.

O efeito do sorriso na percepção psicológica da pessoa

O objectivo do estudo foi o de verificar o efeito do sorriso na percepção psicológica da pessoa em jovens, adultos, idosos e jovens negros. Pretendia-se verificar se o sorriso contribui para os traços diferenciais entre os grupos humanos em estudo e se o mesmo era descritor de género. O estudo envolveu um delineamento transversal analítico ou estudo não-experimental, também classificado por estudo pós-facto, estudo de observação passiva ou estudo correlacional e de observação, de comparação entre grupos, mediante o juízo ou julgamento psicológico da face neutra e do tipo de sorriso contrastados, de matriz factorial 4 x 2 x 2 (face neutra, sorriso fechado, sorriso superior, sorriso largo; género dos estímulos; género dos respondentes) e a sua finalidade foi descrever a percepção psicológica do sorriso em função das variáveis género do estímulo, género do respondente e grupo étnico, na Escala de Percepção do Sorriso (EPS), em formato diferenciador semântico, com 19 itens bipolares opostos, tendo a avaliação sido feita numa escala ordinal de 1 a 7 pontos, nas dimensões Avaliação (12 itens) e Movimento Expressivo (7 itens) resultante dos estudos preliminares sobre a atractividade facial (estudo preliminar 1) e a escolha de dípolos de adjectivos preditores para percepção psicológica da face neutra (estudo preliminar 2). Nos estudos principais 1, 2 e 3 foram utilizados 24 estímulos fotográficos apresentando o tipo de sorriso (fechado, superior e largo) e a face neutra (12 do estímulo mulher e 12 do estímulo homem) referentes aos três grupos etários (18-25 anos, 40-50 anos e 60-70 anos) e a Escala de Percepção do Sorriso (EPS) foi aplicada a uma amostra não probabilística ou intencional do tipo homogénea de 480 participantes portugueses de ambos os géneros (240 mulheres e 240 homens) distribuídos por grupos etários de jovens (80 mulheres e 80 homens, média: 22.2 anos), adultos (80 mulheres e 80 homens, média: 43.1 anos) e idosos (80 mulheres e 80 homens, média: 65.0 anos) No estudo principal 4, foram utilizados 8 estímulos fotográficos apresentando o tipo de sorriso (fechado, superior e largo) e a face neutra (4 do estímulo mulher e 4 do estímulo homem) de universitários de Cabo Verde, a estudar em Portugal, e a Escala de Percepção do Sorriso (EPS) foi aplicada a uma amostra não probabilística ou intencional do tipo homogénea de 160 participantes de ambos os géneros (80 mulheres e 80 homens) e estudantes universitários portugueses (média: 21.8 anos). Os resultados revelam e confirmam o efeito do sorriso na percepção psicológica da pessoa, à semelhança de outros estudos, isto é, sorrir torna a percepção psicológica mais positiva ou negativa e verifica-se que tal sucede em função do género do estímulo e do género do respondente. As diferenças significativas na percepção da face neutra e tipo de sorriso contrastados são justificadas pela pertença de género de quem os percepciona e pela pertença do género de quem é percepcionado. Tal apenas não sucede no factor Avaliação do grupo dos adultos. Os resultados obtidos indicam que, quer no factor Avaliação quer no factor Movimento Expressivo, os tipos de sorriso largo e superior são os que registam médias ponderadas mais elevadas. Pelo contrário, a face neutra e o sorriso fechado registam valores menos elevados na percepção. A análise da percepção da pessoa em função da face neutra e tipo de sorriso contrastados revelou uma correspondência entre a expressão facial, o género do estímulo e o género do respondente. No factor Avaliação, a mulher é percepcionada mais positivamente que o homem, verificando-se o inverso no factor Movimento Expressivo no grupo dos adultos e dos idosos. Verificou-se efeito do sorriso na percepção psicológica dos estímulos de cor negra. No grupo dos jovens que percepcionaram estímulos de cor negra, o homem é considerado mais positivo que a mulher em ambos os factores. O efeito significativo do género revela que a sua percepção é condicionada pelo seu próprio género. Os resultados apontam ainda para a configuração pronunciada de uma hierarquização ascendente da face neutra e tipo de sorriso contrastados em dois conjuntos bem delimitados e distinguindo diferentes formas topográficas de sorrir: a face neutra e o sorriso fechado e o sorriso superior e o sorriso largo.