The Neural Basis of Financial Risk Taking

Investors systematically deviate from rationality when making financial decisions, yet the mechanisms responsible for these deviations have not been identified. Using event-related fMRI, we examined whether anticipatory neural activity would predict optimal and suboptimal choices in a financial decision-making task. We characterized two types of deviations from the optimal investment strategy of a rational risk- neutral agent as risk-seeking mistakes and risk-aversion mistakes. Nucleus accumbens activation preceded risky choices as well as risk- seeking mistakes, while anterior insula activation preceded riskless choices as well as risk-aversion mistakes. These findings suggest that distinct neural circuits linked to anticipatory affect promote different types of financial choices, and indicate that excessive activation of these circuits may lead to investing mistakes. Thus, consideration of anticipatory neural mechanisms may add predictive power to the rational actor model of economic decision-making.neuroeconomics, neurofinance, brain, investing, emotions, affect

The Influence of Affect on Beliefs, Preferences and Financial Decisions

Recent research in neuroeconomics suggests that the same brain areas that generate emotional states are also involved in the processing of information about risk, rewards and punishments. These findings imply that emotions may influence financial decisions in a predictable and parsimonious way. Our evidence suggests that affect -- generated either by exogenous manipulations, or endogenously by outcomes of prior actions -- indeed matters for financial risk taking, and that it does so by changing preferences as well as the belief formation process. Positive and arousing emotional states such as excitement induce people to take more risk, and to be more confident in their ability to evaluate the available investment options, relative to neutral states, while negative emotions such as anxiety have the opposite effects. Moreover, beliefs are updated in a way that is consistent with the self-preservation motive of maintaining positive affect and avoiding negative affect, by not fully taking into account new information that is at odds with the individuals' prior choices. Therefore, characteristics of markets, economic policies or organization design that have an impact on emotional brain circuits may influence decision making and affect important outcomes at the individual and aggregate level.affect, emotions, beliefs, risk taking, learning, limbic system, neuroeconomics, neurofinance

CEO turnover in a competitive assignment framework

There is considerable and widespread concern about whether CEOs are appropriately punished for poor performance. The empirical literature on CEO turnover documents that CEOs are indeed more likely to be forced out if their performance is poor relative to the industry average. However, CEOs are also more likely to be replaced if the industry is doing badly. We show that these empirical patterns are natural and efficient outcomes of a competitive assignment model in which CEOs and firms form matches based on multiple characteristics, and where industry conditions affect the outside options of both managers and firms. Our model also has several new predictions about the type of replacement manager, and their pay and performance. We construct a dataset which describes all turnover events during the period 1992-2006 and show that these predictions are also born out empirically.Executive Turnover; Matching Models; Competitive Assignment; CEO Labor Market

Rank expectations, feedback and social hierarchies

We develop and test experimentally a theoretical model of the role of self-esteem, generated by private feedback regarding relative performance, on the behavior of agents working on an effort provision task for a flat wage. Agents work harder and expect to rank better when they are told they may learn their ranking, relative to cases when they are told feedback will not be provided. Individuals who learn that they have ranked better than expected decrease their output but expect an even better rank in the future, while those who were told they ranked worse than expected increase their output and at the same time lower their rank expectations going forward. These effects are stronger in earlier rounds of the task, while subjects learn how they compare to their peers. This rank hierarchy is established early on, and remains relatively stable afterwards. Private relative rank information helps create a ratcheting effect in the group's average output, which is mainly due to the fight for dominance at the top of the hierarchy. Hence, in environments where monetary incentives are weak, moral hazard may be mitigated by providing feedback to agents regarding their relative performance, and by optimally choosing the reference peer group.rankings, incentives, feedback, moral hazard, intrinsic motivation, ego utility, self-esteem

University of Dayton Core program honors three students with Herbenick Award for excellence in interdisciplinary education

The University of Dayton Core program recognized three students with the Raymond M. Herbenick Award at its 34th annual graduation banquet, marking the first time in the program’s history that a trio of students won the award

Abnormal Neuromuscular Fatigue and Motor Performance of the Knee Extensors Post Stroke

Stroke causes paresis in leg muscles, such as the knee extensors, that significantly impairs motor control and function during tasks such as walking. Reduced endurance and increased kinematic asymmetries during walking over time indicate paretic musculature may fatigue more quickly than non-paretic musculature. The primary purpose of this study was to identify abnormalities in neuromuscular fatigue (reduction in force over time) of the paretic knee extensors and associate them with motor performance. We investigated the effects of repeated six second isometric submaximal (30% of maximum voluntary contraction) knee extensor fatiguing contractions on task failure and motor performance in ten chronic stroke subjects and compared them to ten, healthy controls. A systematic criterion determined task failure. We recorded knee extensor torque, stretch reflex responses, surface electromyography (EMG) of agonist (rectus femoris and vastus medialis) and antagonist (medial hamstring) knee extensor muscles, and muscle fiber conduction velocity (CV) of the vastus lateralis muscle as interpretive measures of neuromuscular fatigue. A power spectral density analysis of the intermittent target torque estimated the effect of fatigue on force fluctuations. Two isometric submaximal torque tracking tasks performed before and after fatigue provided direct measures of fatigue on force variability and error. Stroke subjects failed the fatiguing task significantly sooner than control subjects. In controls, averaged rectified EMG amplitude significantly increased and CV significantly reduced with fatigue, while no changes occurred in stroke. Fatigue caused a spectral shift toward higher force fluctuation frequencies in control but not stroke subjects. Time to task failure in stroke subjects negatively correlated with their walking speed. Additionally, pre-fatigue torque variability and error was greater in stroke than control subjects, and increased significantly with fatigue. In summary, paretic knee extensors have increased neuromuscular fatigability of the paretic knee extensors which relates to walking speed. The interpretative measures suggest that central factors may contribute more to time-to-task failure as compared to peripheral (muscular factors) in stroke survivors. Performance data demonstrate pre and post-fatigue impairments in sub-maximal force regulation. Taken together, these data demonstrate previously un-described impairments in paretic knee extensor force generation and regulation that could contribute to motor dysfunction post stroke

Regulatory Properties of Membrane Bound Acetylcholinesterase from Red Cell Ghosts

Activating and inhibiting properties of quaternary pyridinium compounds on acetylcholinesterase (AChE), bound to bovine red cell membranes, were investigated. The action of these compounds is mainly due to their quaternary structure, while the effect of the substituents on the pyridinium moeity is less important. The effect of the compounds on the rate of hydrolysis of acetyl-~-metylchoLine (MeCh) is different from the effect on acetylcholine (ACh) hydrolys1s. The effect of toxogonin on the structure-bound enzyme is different from the effect on the water-soluble enzyme, the latter not being activated by toxogonin. V m values were determined by the method of Hofstee. Hill plots yielded several straight lines. It Js postulated that AChE exists in several states of cooperativity (negative, non- and positive cooperativity). The different states are assumed to correspond to different allosteric conformations of the protein. The reactions of structure-bound and water-soluble enzyme are different. In contrast to the bound form, the soluble form could not be activated

Comparação do perfil de carotenoides, vitaminas A e E da gema de ovos comercializados como orgânicos, caipiras e convencionais na grande Florianópolis

TCC (graduação) - Universidade Federal de Santa Catarina. Centro de Ciências Agrárias. Curso de Zootecnia.Os carotenoides são pigmentos vegetais transferidos as gemas dos ovos através da dieta, conferindo cor peculiar às mesmas. Dessa forma, os teores de carotenoides nos ovos e de outros constituintes bioativos podem variar em decorrência de diferenças do sistema de produção. O presente trabalho teve como objetivo comparar o perfil de carotenoides, vitamina A e E nas gemas de ovos produzidos em sistemas de criação convencional (CON), caipira (CAI) e orgânico certificado (ORG). Ovos de dois lotes de três (CON e CAI/ n=6) e duas (ORG/ n=4) marcas foram adquiridos em estabelecimentos comerciais na região da Grande Florianópolis (SC). Os carotenoides foram extraídos a partir de 2,5 g de gema (peso fresco) em solução de NaCl 5%, seguido da adição de etanol e hexano (1:1 v/v). Após centrifugação (3.600 rpm, 20 min) e re-extração com hexano (2x), o resíduo foi saponificado (KOH 10%) e lavado com água destilada (3x). Após centrifugação (3.000 rpm, 5min), os extratos foram submetidos a varredura UV-Vis em espectrofotômetro (200-700 ηm) e analisados por Cromatografia Líquida de Alta Eficiência (CLAE). Foram encontrados 10 carotenoides diferentes, sendo as xantofilas luteína e zeaxantina os compostos majoritários nos extratos analisados. Os conteúdos de carotenoides totais determinado por UV-vis, luteína, zeaxantina e vitamina E nas gemas dos ovos caipiras foram superiores aos convencionais, enquanto os dos ovos orgânicos não diferiram dos outros dois sistemas (p<0,05). Adicionalmente, através da análise dos perfis espectrais usando PCA (PC1 e PC2) foi possível discriminar as amostras de acordo com o sistema de produção. Enquanto a totalidade das amostras ORG e CON separaram-se das demais, metade das amostras CAI foram discriminadas e as restantes agruparam-se com os tratamentos ORG ou CON. Tais resultados foram confirmados pela análise por CLAE, a qual evidenciou um perfil carotenoídico distinto de acordo com o sistema de produção. Em conjunto, tais resultados podem ser explicados pelas diferenças na alimentação dos animais em cada um dos sistemas. Enquanto no sistema CON e ORG tem-se uma dieta controlada, basicamente composta por grãos, a alimentação no sistema CAI é mais diversificada, incluindo forrageiras, folhas diversas, restos de vegetais e alguns grãos. Destaca-se ainda o perfil carotenoídico como marcador químico para distinção de ovos de sistemas alternativos, aplicando-se a técnica de PCA aos perfis UV-vis

Implementação da sistematização da assistência de enfermagem na sala de recuperação pós-anestésica

TCC (graduação em Enfermagem) - Universidade Federal de Santa Catarina, Florianópoli

Tratamento endovascular do trauma arterial.

Trabalho de Conclusão de Curso - Universidade Federal de Santa Catarina, Centro de Ciências da Saúde, Departamento de Clínica Cirúrgica, Curso de Medicina, Florianópolis, 200