Simulation of the Categorization-Elaboration Model of Diversity and Work-Group Performance

The relationship between the diversity of work-groups and their performance continues to be a key concern in the study of organizational behavior. Several models have been proposed to explain this relationship, generally concentrating on the interplay between two main factors: diversity as a source of varied knowledge and viewpoints that a group can draw upon to increase its performance, and diversity as a source of dissention in groups, causing group fracturing and bias, leading to decreases in performance. Recently a model called the categorization-elaboration model (CEM) (van Knippenburg, et. al. 2004) was proposed which integrates existing research in diversity and group performance into a unified framework. We perform an agent-based simulation of the CEM where groups are modeled as coalitions of rational agents which draw from distinct experience pools and which collectively try and solve a simple forecasting problem. We simulate how the performance of the coalition varies with the diversity of the agents\' background experiences, and find that the resulting performance/diversity relationship is curvilinear in nature (specifically, inversely u-shaped), as predicted anecdotally in the van Knippenburg work. Additionally, we find a point of unstable equilibrium in the performance/diversity curve at the no-diversity point, such that at the no-diversity point, small increases in diversity have little or no effect on performance. We point out a connection between the existence of this feature, which would seem to highlight the importance of external diversity-encouraging efforts such as affirmative action-type initiatives and early economic work which suggests that market-based forces should be sufficient to ensure high levels of diversity in organizations.Workgroup Performance, Diversity, Categorization-Elaboration Model, Multi-Agent System, Market Forces

Deception and Convergence of Opinions Part 2: the Effects of Reproducibility

Recently Martins (Martins 2005) published an article in this journal analyzing the opinion dynamics of a neutral observer deciding between two competing scientific theories (Theory A and Theory B). The observer could not perform any experiments to verify either theory, but instead had to form its opinion solely by reading published articles reporting the experimental results of others. The observer was assumed to be rational (modeled with simple Bayesian rules) and the article examined how the observer\'s confidence in the correctness of the two theories changed as a function of number of articles read in support of each theory, and how much, if any, deception was believed to be present in the published articles. A key (and somewhat disturbing) result of this work was that for even relatively small amounts of perceived deception in the source articles, the observer could never be reasonably sure of which theory (A or B) was correct, even in the limit of the observer reading an infinite number of such articles. In this work we make a small extension to the Martins article by examining what happens when the observer only considers experimental results which have been reproduced by multiple parties. We find that even if the observer only requires that the articles he or she reads be verified by one additional party, its confidence in one of the two theories can converge to unity, regardless of the amount of amount of deception believed to be present in the source articles.Opinion Dynamics, Epistemology, Rational Agents, Deception, Confirmation Theory

Scaling reinforcement learning to the unconstrained multi-agent domain

Reinforcement learning is a machine learning technique designed to mimic the way animals learn by receiving rewards and punishment. It is designed to train intelligent agents when very little is known about the agent’s environment, and consequently the agent’s designer is unable to hand-craft an appropriate policy. Using reinforcement learning, the agent’s designer can merely give reward to the agent when it does something right, and the algorithm will craft an appropriate policy automatically. In many situations it is desirable to use this technique to train systems of agents (for example, to train robots to play RoboCup soccer in a coordinated fashion). Unfortunately, several significant computational issues occur when using this technique to train systems of agents. This dissertation introduces a suite of techniques that overcome many of these difficulties in various common situations. First, we show how multi-agent reinforcement learning can be made more tractable by forming coalitions out of the agents, and training each coalition separately. Coalitions are formed by using information-theoretic techniques, and we find that by using a coalition-based approach, the computational complexity of reinforcement-learning can be made linear in the total system agent count. Next we look at ways to integrate domain knowledge into the reinforcement learning process, and how this can signifi-cantly improve the policy quality in multi-agent situations. Specifically, we find that integrating domain knowledge into a reinforcement learning process can overcome training data deficiencies and allow the learner to converge to acceptable solutions when lack of training data would have prevented such convergence without domain knowledge. We then show how to train policies over continuous action spaces, which can reduce problem complexity for domains that require continuous action spaces (analog controllers) by eliminating the need to finely discretize the action space. Finally, we look at ways to perform reinforcement learning on modern GPUs and show how by doing this we can tackle significantly larger problems. We find that by offloading some of the RL computation to the GPU, we can achieve almost a 4.5 speedup factor in the total training process

Magnetocaloric Effect Caused by Paramagnetic Austenite–Ferromagnetic Martensite Phase Transformation

In the present work, the magnetization of Ni50Mn17.5Ga25Cu7.5 alloy undergoing the first-order phase transition from paramagnetic austenite to ferromagnetic martensite was measured to evaluate the magnetic-field-induced entropy change (MFIEC) and refrigerant capacity (RC) of the alloy. A standard method (SM) of evaluation of MFIEC is based on thermodynamic Maxwell relation. In view of the criticism of SM expressed by some scientists, the alternative method (AM), which is based on thermodynamic relationships for free energy, was proposed recently for the determination of MFIEC. We developed this method and computed MFIEC in two ways—by AM and SM. The values of MFIEC obtained for Ni50Mn17.5Ga25Cu7.5 alloy by these methods appeared to be large but very different from each other. Moreover, AM reveals the possibility of both normal and inverse magnetocaloric effects in the adjoining temperature ranges, while SM results only in the normal magnetocaloric effect.This research was funded by AEI/FEDER, UE (projects MAT2014-56116-C04-01-R and MAT2012- 37923-C02-01), NASU (project 0117U000433), MESU (project 0117U004340) and SFFR (President’s of Ukraine grant F75/156-2018)

The counter-streaming instability in dwarf ellipticals with off-center nuclei

n many nucleated dwarf elliptical galaxies (dE,N's), the nucleus is offset by a significant fraction of the scale radius with respect to the center of the outer isophotes. Using a high-resolution N-body simulation, we demonstrate that the nucleus can be driven off-center by the m=1 counterstreaming instability, which is strong in flattened stellar systems with zero rotation. The model develops a nuclear offset on the order of 30% of the exponential scale length. We compare our numerical results with the photometry and kinematics of FCC 046, a Fornax Cluster dE,N with a nucleus offset by 1.2" we find good agreement between the model and FCC 046. We also discuss mechanisms that may cause counterrotation in dE,N's and conclude that the destruction of box orbits in an initially triaxial galaxy is the most promising.Comment: 5 pages, 4 figure

Precision metering of microliter volumes of biological fluids in micro-gravity

Concepts were demonstrated and investigated for transferring accurately known and reproducible microliter volumes of biological fluids from sample container onto dry chemistry slides in microgravity environment. Specific liquid transfer tip designs were compared. Information was obtained for design of a liquid sample handling system to enable clinical chemical analysis in microgravity. Disposable pipet tips and pipet devices that were designed to transfer microliter volumes of biological fluid from a (test tube) sample container in 1-G environment were used during microgravity periods of parabolic trajectories of the KC-135 aircraft. The transfer process was recorded using charge coupled device camera and video cassette equipment. Metering behavior of water, a synthetic aqueous protein solution, and anticoagulated human blood was compared. Transfer of these liquids to 2 substrate materials representative of rapidly wettable and slowly wettable dry chemistry slide surface was compared

Second Street Gangs: Ad Hoc Policy Commissions in the Senate

Recent debates in the US Congress over major policy issues, such as the US debt ceiling, the use of the filibuster in the Senate, and health care reform, have witnessed the emergence of small groups of legislators -- given names like “The Gang of Six” in popular press -- working to craft a bill that (they may expect) covers the middle-ground between opposing factions. Given the usual expectations that, 1) committee members are not preference outliers, and 2) committees have better policy expertise than the average chamber member, what purpose do these small groups serve? The argument here is that these gangs represent a focal point for accusations of ideological compromise and potential blame (if the product does not proceed to a floor vote). As partisanship in Congress has increased, the cost of compromise has increased, which may make the otherwise jurisdictionally-appropriate committee members less inclined to allow bills that would appeal to moderate voters to progress. Allowing other legislators to so visibly drive the work on moderate bills deflects the extremists from accusations of being “soft.” At the same time the heightened attention on the gang raises the reputational costs of failure. We should expect, then, to see gang membership to be comprised of more ideologically moderate members, who have served longer or who have won their seats by a wide margin (making them better able to absorb the reputational cost of failure). We review the (small) number of cases of emergent gangs to examine the model\u27s comportment with observed behavior

Comparison of different phosphorous adsorption models in acid forest soils of Bityili (Southern – Cameroon) and their relationship with soil properties

This study was designed to compare the phosphorous fixation capacity of three soils series named Tyele, Minkonmingon and Mekoto in the south region of Cameroon and to determine the soil properties that are the main predictors of the P activity of those soils. Five adsorption equations viz. Linear, Langmuir, Van Huay, Freundlich and Temkin were used to describe P adsorption processes. The results of the study showed that maximum adsorbed P of Minkonmingon, Tyele and Mekoto was 936.09, 311.15 and 823.37 mg kg -1 of soils respectively with the mean of 690.20 mg kg -1 of soils. By applying various models, P adsorption data revealed that for low concentration range, the Freundlich equation show a better fit followed by the Langmuir, Van Huay, Temkin and Linear equations. It can be thus concluded from the adsorption and Spearman correlation analysis that the soil of Minkonmingon has a greater capacity to fix P followed by those of Mekoto and Tyele respectively with silt, exchangeable acidity, free aluminum, potassium and soil organic carbon and pH KCl being the main predictors of P activity in these soils.© 2016 International Formulae Group. All rights reserved.Keywords: Phosphorous fixation, adsorption isotherms, soil characteristics, correlation, acid soils, Cameroo

Composites technology for transport primary structure

The ACT contract activity being performed by the McDonnell Douglas Corporation is divided into two separate activities: one effort by Douglas Aircraft in Long Beach, California with a focus on Transport Primary Wing and Fuselage Structure, and the other effort by McDonnell Aircraft in St. Louis, Missouri with a focus on Advanced Combat Aircraft Center Wing-Fuselage Structure. This presentation is on the Douglas Aircraft Transport Structure portion of the ACT program called ICAPS - Innovative Composite Aircraft Primary Structure