Food reinforcement, the dopamine D? receptor genotype, and energy intake in obese and nonobese humans.

[Correction Notice: An erratum for this article was reported in Vol 122(1) of Behavioral Neuroscience (see record 2008-01943-025). In the original article, the n values (and corresponding percentages) for the number of people with the A1/A1 & A1/A2 and A2/A2 genotypes were reversed in Table 2. The corrected table appears in the erratum, with the revised numbers appearing in bold font.] The authors measured food reinforcement, polymorphisms of the dopamine D? receptor (DRD?) and dopamine transporter (DAT1) genes, and laboratory energy intake in 29 obese and 45 nonobese humans 18-40 years old. Food reinforcement was greater in obese than in nonobese individuals, especially in obese individuals with the TaqI A1 allele. Energy intake was greater for individuals high in food reinforcement and greatest in those high in food reinforcement with the TaqI A1 allele. No effect of the DAT1 genotype was observed. These data show that individual differences in food reinforcement may be important for obesity and that the DRD? genotype may interact with food reinforcement to influence energy intake. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Food reinforcement and eating: A multilevel analysis.

Eating represents a choice among many alternative behaviors. The purpose of this review is to provide an overview of how food reinforcement and behavioral choice theory are related to eating and to show how this theoretical approach may help organize research on eating from molecular genetics through treatment and prevention of obesity. Special emphasis is placed on how food reinforcement and behavioral choice theory are relevant to understanding excess energy intake and obesity and how they provide a framework for examining factors that may influence eating and are outside of those that may regulate energy homeostasis. Methods to measure food reinforcement are reviewed, along with factors that influence the reinforcing value of eating. Contributions of neuroscience and genetics to the study of food reinforcement are illustrated by using the example of dopamine. Implications of food reinforcement for obesity and positive energy balance are explored, with suggestions for novel approaches to obesity treatment based on the synthesis of behavioral and pharmacological approaches to food reinforcement. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On Lifetime-Based Node Failure and Stochastic Resilience of Decentralized Peer-to-Peer Networks

To model P2P networks that are commonly faced with high rates of churn and random departure decisions by end-users, this paper investigates the resilience of random graphs to lifetime-based node failure and derives the expected delay before a user is forcefully isolated from the graph and the probability that this occurs within his/her lifetime. Using these metrics, we show that systems with heavy-tailed lifetime distributions are more resilient than those with light-tailed (e.g., exponential) distributions and that for a given average degree, k-regular graphs exhibit the highest level of fault tolerance. As a practical illustration of our results, each user in a system with n = 100 billion peers, 30-minute average lifetime, and 1-minute node-replacement delay can stay connected to the graph with probability 1 - 1/n using only 9 neighbors. This is in contrast to 37 neighbors required under previous modeling efforts. We finish the paper by observing that many P2P networks are almost surely (i.e., with probability 1 - o(1)) connected if they have no isolated nodes and derive a simple model for the probability that a P2P system partitions under churn.     

Computer-mediated group influence on ethical behavior

Drawing on previous research in ethical behavior in information technology, this study examines the effects of group discussion, using virtual teams, on an individual’s intention to behave ethically/unethically. It was hypothesized that behavioral intention would be influenced by an individual’s attitude (toward ethical behavior), personal normative beliefs, ego strength, locus of control, perceived importance, gender and the scenario, and that computer-mediated group discussion would impact an individual’s ethical behavioral intention. This was tested through an experiment using five different ethical scenarios involving information technology. The results show that for two of the five scenarios, individual behavioral intention was significantly more unethical after computer-mediated group discussion than before, while for one scenario, individual behavioral intention was significantly more ethical after computer-mediated group discussion than before. The results of this study may help organizations to develop realistic training programs for IT professionals that account for changes in employee’s personal ethical models after interacting with others.     

Network numerical analysis for the smoother and the lagged joint-process estimator

Motivated by the fact that the a priori least-squares-order-recursive lattice (LSORL) smoother is more robust than the LSORL joint-process estimator with lagged desired signals in the finite precision, we model numerical properties of the two algorithms by virtue of previous efforts. Then, we give the reason why the smoother is substantially more robust than the lagged joint-process estimator by providing the explicit analysis for the performance difference of the two algorithms.     

On simultaneous on-line state and parameter estimation in non-linear state-space models

On-line estimation plays an important role in process control and monitoring. Obtaining a theoretical solution to the simultaneous state-parameter estimation problem for non-linear stochastic systems involves solving complex multi-dimensional integrals that are not amenable to analytical solution. While basic sequential Monte-Carlo (SMC) or particle filtering (PF) algorithms for simultaneous estimation exist, it is well recognized that there is a need for making these on-line algorithms non-degenerate, fast and applicable to processes with missing measurements. To overcome the deficiencies in traditional algorithms, this work proposes a Bayesian approach to on-line state and parameter estimation. Its extension to handle missing data in real-time is also provided. The simultaneous estimation is performed by filtering an extended vector of states and parameters using an adaptive sequential-importance-resampling (SIR) filter with a kernel density estimation method. The approach uses an on-line optimization algorithm based on Kullback–Leibler (KL) divergence to allow adaptation of the SIR filter for combined state-parameter estimation. An optimal tuning rule to control the width of the kernel and the variance of the artificial noise added to the parameters is also proposed. The approach is illustrated through numerical examples.     

Practitioner's Insight: Learning to Manage Emerging Technologies

New management techniques and policies need to be developed in order for more effective commercialization of emerging technologies.     

Characterization of IS1547, a new member of the IS900 family in the Mycobacterium tuberculosis complex, and its association with IS6110

Unlike classically defined insertion sequence (IS) elements, which are delimited by their inverted terminal repeats, some IS elements do not have inverted terminal repeats. Among this group of atypical IS elements, IS116, IS900, IS901, and IS1110 have been proposed as members of the IS900 family of elements, not only because they do not have inverted terminal repeats but also because they share other features such as homologous transposases and particular insertion sites. In this study, we report a newly identified IS sequence, IS1547, which was first identified in a clinical isolate of Mycobacterium tuberculosis. Its structure, insertion site, and putative transposase all conform with the conventions of the IS900 family, suggesting that it is a new member of this family. IS1547 was detected only in isolates of the M. tuberculosis complex, where it had highly polymorphic restriction fragment length polymorphism patterns, suggesting that it may be a useful genetic marker for identifying isolates of the M. tuberculosis complex and for distinguishing different strains of M. tuberculosis. ipl is a preferential locus for IS6110 insertion where there are eight known different insertion sites for IS6110. Surprisingly, the DNA sequence of ipl is now known to be a part of IS1547, meaning that IS1547 is a preferential site for IS6110 insertion.     

A cylindrical Rayleigh�CTaylor instability: radial outflow from pipes or stars

The classical Rayleigh?CTaylor instability refers to a situation in which two inviscid fluids lie in horizontal layers, with a sharp interface separating them. The upper fluid is heavier, and so disturbances to the interface are unstable and grow with time. The present paper considers the analogous planar flow in cylindrical geometry. A light fluid is being produced by a line source at the origin, and is separated by a sharp interface from a surrounding more dense fluid. As the interface is forced outward, small disturbances to the flow grow with time. There is a finite critical time at which the curvature at the interface evidently becomes infinite, as in the planar case, and inviscid theory fails to be valid beyond this time. By introducing viscosity, it is argued that the high interfacial curvatures in the inviscid model are associated with formation of regions of large vorticity at the interface, and these serve as triggers for the interface to roll up into plume structures. A linearized inviscid theory is presented, and methods for computing nonlinear solutions in the inviscid and viscous models are outlined. Different solution modes exist, in which integer numbers of plumes are formed on the cylindrical outflow, and these are presented and discussed. The second mode, representing bi-polar symmetry, may be of particular relevance in astrophysical applications.