On the evolution of behaviors through embodied imitation

© 2015 Massachusetts Institute of Technology. Abstract This article describes research in which embodied imitation and behavioral adaptation are investigated in collective robotics. We model social learning in artificial agents with real robots. The robots are able to observe and learn each others' movement patterns using their on-board sensors only, so that imitation is embodied. We show that the variations that arise from embodiment allow certain behaviors that are better adapted to the process of imitation to emerge and evolve during multiple cycles of imitation. As these behaviors are more robust to uncertainties in the real robots' sensors and actuators, they can be learned by other members of the collective with higher fidelity. Three different types of learned-behavior memory have been experimentally tested to investigate the effect of memory capacity on the evolution of movement patterns, and results show that as the movement patterns evolve through multiple cycles of imitation, selection, and variation, the robots are able to, in a sense, agree on the structure of the behaviors that are imitated

FTO gene-lifestyle interactions on serum adiponectin concentrations and central obesity in a Turkish population

The aim of the study was to investigate whether lifestyle factors modify the association fat mass and obesity-associated (FTO) gene single nucleotide polymorphisms (SNPs) and obesity in a Turkish population. The study included 400 unrelated individuals, aged 24-50 years recruited in a hospital setting. Dietary intake and physical activity were assessed using 24-hour dietary recall and self-report questionnaire, respectively. A genetic risk score (GRS) was developed using FTO SNPs, rs9939609 and rs10163409. Body mass index and fat mass index were significantly associated with FTO SNP rs9939609 (P=0.001 and P=0.002, respectively) and GRS (P=0.002 and P=0.003, respectively). The interactions between SNP rs9939609 and physical activity on adiponectin concentrations, and SNP rs10163409 and dietary protein intake on increased waist circumference were statistically significant (Pinteraction=0.027 and Pinteraction=0.044, respectively). This study demonstrated that the association between FTO SNPs and central obesity might be modified by lifestyle factors in this Turkish population

Mechanics of sliding frictional contact for a graded orthotropic half-plane

The main interest in this study is the crack initiation in graded orthotropic materials under sliding contact conditions. We consider the two-dimensional sliding contact problem between a graded orthotropic half-plane and a rigid punch with an arbitrary profile. The orthotropic graded half-plane is modeled as a linearly elastic and locally inhomogeneous orthotropic material with an exponentially varying Young's modulus in the depth direction. The principal axes of orthotropy are assumed to be parallel and perpendicular to the contact surface. The problem is formulated under plane strain or generalized plane stress conditions. Using the standard Fourier transform, the problem is reduced to a singular integral equation, which is solved numerically using Jacobi polynomials. Extensive parametric study is done to determine the effect of the inhomogeneity parameter, beta, the friction coefficient between the half-plane and the stamp, eta, as well as the material orthotropic elastic parameters: the stiffness ratio, delta, the effective Poisson's ratio, nu, and the shear parameter, kappa, on the contact stress distribution and stress intensity factors at the sharp edges of the stamps that may have a bearing on the fatigue and fracture of the graded orthotropic half-plane.The author (A.K.) would like to thank the Scientific and Technological Research Council of Turkey (TUBITAK) for funding this research through the program BIDEB-2218 "Postgraduate Research Fellowship" during her postgraduate studies at TOBB University of Economics and Technology