Understanding the effects of violent video games on violent crime

Psychological studies invariably find a positive relationship between violent video game play and aggression. However, these studies cannot account for either aggressive effects of alternative activities video game playing substitutes for or the possible selection of relatively violent people into playing violent video games. That is, they lack external validity. We investigate the relationship between the prevalence of violent video games and violent crimes. Our results are consistent with two opposing effects. First, they support the behavioral effects as in the psychological studies. Second, they suggest a larger voluntary incapacitation effect in which playing either violent or non-violent games decrease crimes. Overall, violent video games lead to decreases in violent crime. --Video Games,Violence,Crime

Preconditioning Kernel Matrices

The computational and storage complexity of kernel machines presents the primary barrier to their scaling to large, modern, datasets. A common way to tackle the scalability issue is to use the conjugate gradient algorithm, which relieves the constraints on both storage (the kernel matrix need not be stored) and computation (both stochastic gradients and parallelization can be used). Even so, conjugate gradient is not without its own issues: the conditioning of kernel matrices is often such that conjugate gradients will have poor convergence in practice. Preconditioning is a common approach to alleviating this issue. Here we propose preconditioned conjugate gradients for kernel machines, and develop a broad range of preconditioners particularly useful for kernel matrices. We describe a scalable approach to both solving kernel machines and learning their hyperparameters. We show this approach is exact in the limit of iterations and outperforms state-of-the-art approximations for a given computational budget

Fuzzy Modeling and Parallel Distributed Compensation for Aircraft Flight Control from Simulated Flight Data

A method is described that combines fuzzy system identification techniques with Parallel Distributed Compensation (PDC) to develop nonlinear control methods for aircraft using minimal a priori knowledge, as part of NASAs Learn-to-Fly initiative. A fuzzy model was generated with simulated flight data, and consisted of a weighted average of multiple linear time invariant state-space cells having parameters estimated using the equation-error approach and a least-squares estimator. A compensator was designed for each subsystem using Linear Matrix Inequalities (LMI) to guarantee closed-loop stability and performance requirements. This approach is demonstrated using simulated flight data to automatically develop a fuzzy model and design control laws for a simplified longitudinal approximation of the F-16 nonlinear flight dynamics simulation. Results include a comparison of flight data with the estimated fuzzy models and simulations that illustrate the feasibility and utility of the combined fuzzy modeling and control approach

An Investigation of the Effects of Categorization and Discrimination Training on Auditory Perceptual Space

Psychophysical phenomena such as categorical perception and the perceptual magnet effect indicate that our auditory perceptual spaces are warped for some stimuli. This paper investigates the effects of two different kinds of training on auditory perceptual space. It is first shown that categorization training, in which subjects learn to identify stimuli within a particular frequency range as members of the same category, can lead to a decrease in sensitivity to stimuli in that category. This phenomenon is an example of acquired similarity and apparently has not been previously demonstrated for a category-relevant dimension. Discrimination training with the same set of stimuli was shown to have the opposite effect: subjects became more sensitive to differences in the stimuli presented during training. Further experiments investigated some of the conditions that are necessary to generate the acquired similarity found in the first experiment. The results of these experiments are used to evaluate two neural network models of the perceptual magnet effect. These models, in combination with our experimental results, are used to generate an experimentally testable hypothesis concerning changes in the brain's auditory maps under different training conditions.Alfred P. Sloan Foundation and the National institutes of Deafness and other Communication Disorders (R29 02852); Air Force Office of Scientific Research (F49620-98-1-0108

Understanding the effects of violent video games on violent crime

Psychological studies invariably find a positive relationship between violent video game play and aggression. However, these studies cannot account for either aggressive effects of alternative activities video game playing substitutes for or the possible selection of relatively violent people into playing violent video games. That is, they lack external validity. We investigate the relationship between the prevalence of violent video games and violent crimes. Our results are consistent with two opposing effects. First, they support the behavioral effects as in the psychological studies. Second, they suggest a larger voluntary incapacitation effect in which playing either violent or non-violent games decrease crimes. Overall, violent video games lead to decreases in violent crime

Flynn et al. Respond

Comment on Work as an Inclusive Part of Population Health Inequities Research and Prevention. [Am J Public Health. 2018] New Horizons for Occupational Health Surveillance. [Am J Public Health. 2018

Hepatocellular proliferation in response to agonists of peroxisome proliferator-activated receptor alpha: a role for kupffer cells?

BACKGROUND: It has been proposed that PPARα agonists stimulate Kupffer cells in rodents which in turn, release mitogenic factors leading to hepatic hyperplasia, and eventually cancer. However, Kupffer cells do not express PPARα receptors, and PPARα agonists stimulate hepatocellular proliferation in both TNFα- and TNFα receptor-null mice, casting doubt on the involvement of Kupffer cells in the mitogenic response to PPARα agonists. This study was therefore designed to investigate whether the PPARα agonist PFOA and the Kupffer cell inhibitor methylpalmitate produce opposing effects on hepatocellular proliferation and Kupffer cell activity in vivo, in a manner that would implicate these cells in the mitogenic effects of PPARα agonists. METHODS: Male Sprague-Dawley rats were treated intravenously via the tail vein with methylpalmitate 24 hrs prior to perfluorooctanoic acid (PFOA), and were sacrificed 24 hrs later, one hr after an intraperitoneal injection of bromodeoxyuridine (BrdU). Sera were analyzed for TNFα and IL-1β. Liver sections were stained immunohistochemically and quantified for BrdU incorporated into DNA. RESULTS: Data show that PFOA remarkably stimulated hepatocellular proliferation in the absence of significant changes in the serum levels of either TNFα or IL-1β. In addition, methylpalmitate did not alter the levels of these mitogens in PFOA-treated animals, despite the fact that it significantly blocked the hepatocellular proliferative effect of PFOA. Correlation between hepatocellular proliferation and serum levels of TNFα or IL-1β was extremely poor. CONCLUSION: It is unlikely that mechanisms involving Kupffer cells play an eminent role in the hepatic hyperplasia, and consequently hepatocarcinogenicity attributed to PPARα agonists. This conclusion is based on the above mentioned published data and the current findings showing animals treated with PFOA alone or in combination with methylpalmitate to have similar levels of serum TNFα and IL-1β, which are reliable indicators of Kupffer cell activity, despite a remarkable difference in hepatocellular proliferation

Bidirectional Scatter Measurements of a Guided-mode Resonant Filter Photonic Crystal Structure

This work investigates the Bidirectional Scatter Distribution Function (BSDF) at incident angles other than normal and at 544-nm wavelength of a Guided Mode Resonance Filter (GMRF) Photonic Crystal (PC) structure designed for normally incident light at 532 nm. Strong out-coupling of PC diffraction orders into both the transmitted and reflected hemispheres was observed specifically at a 25.7° incidence angle, which we attribute to this incident angle/wavelength pair being a good match to the ( ± 1, 0) PC grating mode. BSDF measurements at incident angles of 15° and 35° also displayed some out-coupled diffraction, though much lower in magnitude, and are also attributed to being a weaker match to the ( ± 1, 0) PC grating mode. Three-dimensional finite-difference time-domain Maxwell\u27s equation simulations demonstrate that since this GMRF was designed for complete destructive interference of the transmitted light upon normal incidence, stronger out-coupling of the diffraction is expected for modal solutions as the angle of incidence increases. © 2012 Optical Society of America