From base-rate to cumulative respect

The tendency to neglect base-rates in judgment under uncertainty may be "notorious," as Barbey & Sloman (B&S) suggest, but it is neither inevitable (as they document; see also Koehler 1996) nor unique. Here we would like to point out another line of evidence connecting ecological rationality to dual processes, the failure of individuals to appropriately judge cumulative probability.

The Neuropsychological Assessment of Cognitive Deficits Considering Measures of Performance Variability

Neuropsychologists often face interpretational difficulties when assessing cognitive deficits, particularly in cases of unclear cerebral etiology. How can we be sure whether a single test score below the population average is indicative of a pathological brain condition or normal? In the past few years, the topic of intra-individual performance variability has gained great interest. On the basis of a large normative sample, two measures of performance variability and their importance for neuropsychological interpretation will be presented in this paper: the number of low scores and the level of dispersion.We conclude that low scores are common in healthy individuals. On the other hand, the level of dispersion is relatively small. Here, base rate information about abnormally low scores and abnormally high dispersion across cognitive abilities are providedto improve the awareness of normal variability and to serve clinicians as additional interpretive measures in the diagnostic process.

Wireless scheduling with partial channel state information: large deviations and optimality

We consider a server serving a time-slotted queued system of multiple packet-based flows, where not more than one flow can be serviced in a single time slot. The flows have exogenous packet arrivals and time-varying service rates. At each time, the server can observe instantaneous service rates for only a subset of flows ( selected from a fixed collection of observable subsets) before scheduling a flow in the subset for service. We are interested in queue length aware scheduling to keep the queues short. The limited availability of instantaneous service rate information requires the scheduler to make a careful choice of which subset of service rates to sample. We develop scheduling algorithms that use only partial service rate information from subsets of channels, and that minimize the likelihood of queue overflow in the system. Specifically, we present a new joint subset-sampling and scheduling algorithm called Max-Exp that uses only the current queue lengths to pick a subset of flows, and subsequently schedules a flow using the Exponential rule. When the collection of observable subsets is disjoint, we show that Max-Exp achieves the best exponential decay rate, among all scheduling algorithms that base their decision on the current ( or any finite past history of) system state, of the tail of the longest queue. To accomplish this, we employ novel analytical techniques for studying the performance of scheduling algorithms using partial state, which may be of independent interest. These include new sample-path large deviations results for processes obtained by non-random, predictable sampling of sequences of independent and identically distributed random variables. A consequence of these results is that scheduling with partial state information yields a rate function significantly different from scheduling with full channel information. In the special case when the observable subsets are singleton flows, i.e., when there is effectively no a priori channel state information, Max-Exp reduces to simply serving the flow with the longest queue; thus, our results show that to always serve the longest queue in the absence of any channel state information is large deviations optimal.

When does information about causal structure improve statistical reasoning?

Base rate neglect on the mammography problem can be overcome by explicitly presenting a causal basis for the typically vague false-positive statistic. One account of this causal facilitation effect is that people make probabilistic judgements over intuitive causal models parameterized with the evidence in the problem. Poorly defined or difficult-to-map evidence interferes with this process, leading to errors in statistical reasoning. To assess whether the construction of parameterized causal representations is an intuitive or deliberative process, in Experiment 1 we combined a secondary load paradigm with manipulations of the presence or absence of an alternative cause in typical statistical reasoning problems. We found limited effects of a secondary load, no evidence that information about an alternative cause improves statistical reasoning, but some evidence that it reduces base rate neglect errors. In Experiments 2 and 3 where we did not impose a load, we observed causal facilitation effects. The amount of Bayesian responding in the causal conditions was impervious to the presence of a load (Experiment 1) and to the precise statistical information that was presented (Experiment 3). However, we found less Bayesian responding in the causal condition than previously reported. We conclude with a discussion of the implications of our findings and the suggestion that there may be population effects in the accuracy of statistical reasoning.

An examination of the base rates of post-concussion symptoms : the influence of demographics and depression

Post-concussion syndrome (PCS) is a controversial constellation of cognitive, emotional, and physical symptoms that some patients experience following a mild traumatic brain injury or concussion. PCS-like symptoms are commonly found in individuals with depression, pain, and stress, as well as healthy individuals. This study investigated the base rate of PCS symptoms in a healthy sample of 96 participants and examined the relationship between these symptoms, depression, and sample demographics. PCS symptoms were assessed using the British-Columbia Post-Concussion Symptom Inventory. Depression was measured using the Beck Depression Inventory II. Results demonstrated that: The base rate of PCS was very high; there was a strong positive relationship between depression and PCS; and demographic characteristics were not related to PCS in this sample. These findings are broadly consistent with literature suggesting a significant role for non-neurological factors in the expression of PCS symptomatology. This study adds to the growing body of literature that calls for caution in the clinical interpretation of results from PCS symptom inventories.

Vision-based estimation of airborne target pseudobearing rate using hidden Markov model filters

The problem of estimating pseudobearing rate information of an airborne target based on measurements from a vision sensor is considered. Novel image speed and heading angle estimators are presented that exploit image morphology, hidden Markov model (HMM) filtering, and relative entropy rate (RER) concepts to allow pseudobearing rate information to be determined before (or whilst) the target track is being estimated from vision information.

Proportional navigation with delayed line-of-sight rate

This brief discusses the convergence analysis of proportional navigation (PN) guidance law in the presence of delayed line-of-sight (LOS) rate information. The delay in the LOS rate is introduced by the missile guidance system that uses a low cost sensor to obtain LOS rate information by image processing techniques. A Lyapunov-like function is used to analyze the convergence of the delay differential equation (DDE) governing the evolution of the LOS rate. The time-to-go until which decreasing behaviour of the Lyapunov-like function can be guaranteed is obtained. Conditions on the delay for finite time convergence of the LOS rate are presented for the linearized engagement equation. It is observed that in the presence of line-of-sight rate delay, increasing the effective navigation constant of the PN guidance law deteriorates its performance. Numerical simulations are presented to validate the results.

Cloud base height and cosmic rays

Cosmic rays modify current flow in the global atmospheric electrical circuit. Charging at horizontal layer cloud edges has been observed to be consistent with global circuit vertical current flow through the cloud, which can modify the properties of small and pure water droplets. Studies have been hampered by the absence of cloud edge observations, hence cloud base height information is investigated here. Cloud base height measured at the Lerwick Observatory, Shetland, UK, is analysed using threshold tests and spectral analysis. The cloud base height distributions for low cloud (cloud base less than 800 m) are found to vary with cosmic ray conditions. Further, 27 day and 1.68 year periodicities characteristic of cosmic ray variations are present, weakly, in the cloud base height data of stratiform clouds, when such periodicities are present in neutron monitor cosmic ray data. These features support the idea of propagation of heliospheric variability into layer clouds, through the global atmospheric electric circuit.

Predicting outliers in ensemble forecasts

An ensemble forecast is a collection of runs of a numerical dynamical model, initialized with perturbed initial conditions. In modern weather prediction for example, ensembles are used to retrieve probabilistic information about future weather conditions. In this contribution, we are concerned with ensemble forecasts of a scalar quantity (say, the temperature at a specific location). We consider the event that the verification is smaller than the smallest, or larger than the largest ensemble member. We call these events outliers. If a K-member ensemble accurately reflected the variability of the verification, outliers should occur with a base rate of 2/(K + 1). In operational forecast ensembles though, this frequency is often found to be higher. We study the predictability of outliers and find that, exploiting information available from the ensemble, forecast probabilities for outlier events can be calculated which are more skilful than the unconditional base rate. We prove this analytically for statistically consistent forecast ensembles. Further, the analytical results are compared to the predictability of outliers in an operational forecast ensemble by means of model output statistics. We find the analytical and empirical results to agree both qualitatively and quantitatively.

Monitoramento das reações fisiológicas em sujeitos autistas decorrentes da influência dos sons: um estudo em Engenharia biomédica

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Processos dependentes de informação em empresas incubadas e graduadas de base tecnológica: um estudo comparativo de casos

A competitividade, atualmente, introduz novos comportamentos e leva empresas a uma situação de desconforto e, muitas vezes, a não adaptação às exigências ambientais. Percebe-se um crescente número de desafios associados com o controle de informação em organizações com atividades de engenharia, em particular os volumes crescentes de informação de natureza continuamente mutável. Pode-se afirmar que o desempenho inovador de uma organização é diretamente proporcional a sua capacidade de gerenciar informações. Desta forma, a importância da gestão da informação é reconhecida em detrimento da procura de meios mais competentes para atender demandas atuais. O artigo teve como propósito analisar doze processos dependentes de informação em empresas de base tecnológica, através das principais fases do processo de gerenciamento da informação. Optou-se pelo emprego do método comparativo de casos e pela pesquisa qualitativa, realizada em nove empresas de base tecnológica, as quais se encontravam incubadas ou que passaram recentemente pela fase de incubação no Parque Tecnológico da cidade de São Carlos, do estado de São Paulo. Entre os principais resultados, constatou-se que, nas empresas graduadas, a gestão da informação e seus procedimentos foram identificados de forma mais consciente e estruturados em relação às empresas incubadas.

Studio e ricostruzione delle distribuzioni granulometriche interne al grano in motori a propellente solido

The main purposes of this essay were to investigate in detail the burning rate anomaly phenomenon, also known as "Hump Effect", in solid rocket motors casted in mandrel and the mechanisms at the base of it, as well as the developing of a numeric code, in Matlab environment, in order to obtain a forecasting tool to generate concentration and orientation maps of the particles within the grain. The importance of these analysis is due to the fact that the forecasts of ballistics curves in new motors have to be improved in order to reduce the amount of experimental tests needed for the characterization of their ballistic behavior. This graduate work is divided into two parts. The first one is about bidimensional and tridimensional simulations on z9 motor casting process. The simulations have been carried out respectively with Fluent and Flow 3D. The second one is about the analysis of fluid dynamic data and the developing of numeric codes which give information about the concentration and orientation of particles within the grain based on fluid strain rate information which are extrapolated from CFD software.

Attentional blink and impulsiveness: evidence for higher functional impulsivity in non-blinkers compared to blinkers

The attentional blink (AB) represents a fundamental limit of information processing. About 5-10 % of all subjects, however, do not show the AB. Because of the low base rate of these so-called non-blinkers, studies on mechanisms underlying non-blinkers' absent AB are extremely scant. The few existent studies found non-blinkers to be faster and more efficient in information processing compared to blinkers. A personality trait that has been linked previously to speed and efficiency of information processing as well as to the magnitude of the AB is impulsivity. Therefore, the present study investigated whether 15 non-blinkers and 15 blinkers differed from each other in functional and/or dysfunctional impulsivity. To obtain a better understanding of the underlying processing mechanisms, the P300 component in the event-related potential was recorded during performance on the AB task. Our results indicated higher functional impulsivity in non-blinkers compared to blinkers but no differences between the two groups in dysfunctional impulsivity. As indicated by shorter P300 latency, non-blinkers processed information faster than blinkers after the AB period but slower during the AB period. These speed effects, however, were not associated with functional impulsivity. Thus, impulsivity and speed of information processing appear to represent two rather independent sources for non-blinkers' absent AB