Transforming modern representative democracy via advanced telecommunications: voting from the home, deliberative polling, electronic town meetings, the Internet

We live in a time of great, unique and extremely rapid change. In terms of human communications, we are experiencing a time of profound transformation. And though many predicted this epoch, even envisioned it, it still comes as a surprise. Because as is the case in any transformational era, one gets carried along with the completely unpredictable surge of events and how novel technologies are being used in totally new ways and with wholly unintended consequences

Complementary equations: a fractional differential equation and a Volterra integral equation

Abstract. It is shown that a continuous, absolutely integrable function satisfies the initial value problem Dqx(t) = f (t, x(t)), lim t→0+ t1−qx(t) = x0 (0 < q < 1) on an interval (0, T] if and only if it satisfies the Volterra integral equation x(t) = x0tq−1 + 1 Γ(q) ∫ t 0 (t − s)q−1 f (s, x(s)) ds on this same interval. In contradistinction to established existence theorems for these equations, no Lipschitz condition is imposed on f (t, x). Examples with closed-form solutions illustrate this result

The design of a control architecture for a heavy-lift precision manipulator for use in contact with the environment

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2006."June 2006."Includes bibliographical references (leaves 117-121).Robotic manipulators can be used to enhance the strength and dexterity of a human user. This thesis considers the design of a controller for a heavy-lift manipulator for lifting and inserting payloads onto aircraft on the deck of a ship. The purpose of this robot is to reduce manpower requirements aboard the ship, and reduce the physical requirements for the individuals loading the payloads onto an aircraft. This particular application presents several control challenges, including structural resonances, complex interaction with the environment, high joint friction that varies over time, tight tolerances for the insertion tasks, and ship motions. This thesis builds upon previous works by Garretson [17] and DiCicco [9] by further developing an insertion control mode for intuitive human interaction with the payload of the manipulator when in contact with the environment. These control algorithms, as well as those developed in the previous work, are also validated on a laboratory manipulator. This thesis contains a detailed description of the control architecture for the heavy lift manipulator, including the insertion control mode and a position control mode for use when the manipulator is not in contact with the environment. Both architectures are validated with dynamic simulation models.(cont.) The position control response of this manipulator is shown to be improved with the implementation of friction compensation. In some joints, outputs from an adaptive friction estimator are used to make feed-forward models of friction for use during environmental contact. The position and insertion controllers are then evaluated under open-loop and human control on a laboratory manipulator.by William T. Becker, III.S.M

On the Meaning of the “P Factor” in Symmetrical Bifactor Models of Psychopathology: Recommendations for Future Research From the Bifactor-(S−1) Perspective

Symmetrical bifactor models are frequently applied to diverse symptoms of psychopathology to identify a general P factor. This factor is assumed to mark shared liability across all psychopathology dimensions and mental disorders. Despite their popularity, however, symmetrical bifactor models of P often yield anomalous results, including but not limited to nonsignificant or negative specific factor variances and nonsignificant or negative factor loadings. To date, these anomalies have often been treated as nuisances to be explained away. In this article, we demonstrate why these anomalies alter the substantive meaning of P such that it (a) does not reflect general liability to psychopathology and (b) differs in meaning across studies. We then describe an alternative modeling framework, the bifactor-(S−1) approach. This method avoids anomalous results, provides a framework for explaining unexpected findings in published symmetrical bifactor studies, and yields a well-defined general factor that can be compared across studies when researchers hypothesize what construct they consider “transdiagnostically meaningful” and measure it directly. We present an empirical example to illustrate these points and provide concrete recommendations to help researchers decide for or against specific variants of bifactor structure

Social Preferences and the Efficiency of Bilateral Exchange

Under what conditions do social preferences, such as altruism or a concern for fair outcomes, generate efficient trade? I analyze theoretically a simple bilateral exchange game: Each player sequentially takes an action that reduces his own material payoff but increases the other player’s. Each player’s preferences may depend on both his/her own material payoff and the other player’s. I identify necessary conditions and sufficient conditions on the players’ preferences for the outcome of their interaction to be Pareto efficient. The results have implications for interpreting the rotten kid theorem, gift exchange in the laboratory, and gift exchange in the field

Modelling and Bayesian analysis of the Abakaliki smallpox data

The celebrated Abakaliki smallpox data have appeared numerous times in the epidemic modelling literature, but in almost all cases only a specific subset of the data is considered. The only previous analysis of the full data set relied on approximation methods to derive a likelihood and did not assess model adequacy. The data themselves continue to be of interest due to concerns about the possible re-emergence of smallpox as a bioterrorism weapon. We present the first full Bayesian statistical analysis using data-augmentation Markov chain Monte Carlo methods which avoid the need for likelihood approximations and which yield a wider range of results than previous analyses. We also carry out model assessment using simulation-based methods. Our findings suggest that the outbreak was largely driven by the interaction structure of the population, and that the introduction of control measures was not the sole reason for the end of the epidemic. We also obtain quantitative estimates of key quantities including reproduction numbers

Strong signature of natural selection within an FHIT intron implicated in prostate cancer risk

Previously, a candidate gene linkage approach on brother pairs affected with prostate cancer identified a locus of prostate cancer susceptibility at D3S1234 within the fragile histidine triad gene (FHIT), a tumor suppressor that induces apoptosis. Subsequent association tests on 16 SNPs spanning approximately 381 kb surrounding D3S1234 in Americans of European descent revealed significant evidence of association for a single SNP within intron 5 of FHIT. In the current study, resequencing and genotyping within a 28.5 kb region surrounding this SNP further delineated the association with prostate cancer risk to a 15 kb region. Multiple SNPs in sequences under evolutionary constraint within intron 5 of FHIT defined several related haplotypes with an increased risk of prostate cancer in European-Americans. Strong associations were detected for a risk haplotype defined by SNPs 138543, 142413, and 152494 in all cases (Pearson's χ2 = 12.34, df 1, P = 0.00045) and for the homozygous risk haplotype defined by SNPs 144716, 142413, and 148444 in cases that shared 2 alleles identical by descent with their affected brothers (Pearson's χ2 = 11.50, df 1, P = 0.00070). In addition to highly conserved sequences encompassing SNPs 148444 and 152413, population studies revealed strong signatures of natural selection for a 1 kb window covering the SNP 144716 in two human populations, the European American (π = 0.0072, Tajima's D= 3.31, 14 SNPs) and the Japanese (π = 0.0049, Fay & Wu's H = 8.05, 14 SNPs), as well as in chimpanzees (Fay & Wu's H = 8.62, 12 SNPs). These results strongly support the involvement of the FHIT intronic region in an increased risk of prostate cancer. © 2008 Ding et al