University of Winnipeg

About: University of Winnipeg is a education organization based out in Winnipeg, Manitoba, Canada. It is known for research contribution in the topics: Population & Context (language use). The organization has 3235 authors who have published 6413 publications receiving 150564 citations. The organization is also known as: U of W.

Effects of Existential Anxiety and Self-Esteem on the Perception of Others

Abstract: Previous research has demonstrated that when people are led to think about death they later exhibit more polarized judgments of ingroup and outgroup members. This reaction has been interpreted as an attempt to defend against existential anxiety by seeing oneself as a secure member of a meaning-conveying cultural group. This study examined the moderating influence of self-esteem and found that the polarization effect in response to mortality primes was most pronounced for high self-esteem individuals. An additional manipulation of meaninglessness-anxiety was unsuccessful in producing polarization, lending support to the theoretical centrality of death concerns. We discuss the relevance of these findings to terror management theory (Solomon, Greenberg, & Pyszczynski, 1991).

Position-based impedance control of an industrial hydraulic manipulator

Abstract: This article addresses the problem of impedance control in hydraulic manipulators. Whereas most impedance and hybrid force/position control formulations have focused on electrically driven robots with controllable actuator torques, torque control of hydraulic actuators is a difficult task. A position-based impedance controller (PBIC) is proposed and demonstrated on an existing industrial hydraulic robot (a Unimate MKII-2000). A nonlinear proportional-integral (NPI) controller is first developed to meet the accurate positioning requirements of this impedance control formulation. The NPI controller is shown to make the manipulator match a range of second-order target impedances. Various experiments in free space and in environmental contact, including a simple impedance modulation experiment, demonstrate the feasibility and the promise of the technique. Finally, explanation of an experimentally observed behaviour is offered, suggesting a basic limitation to the implementation of impedance control.

Magnetic properties of the geometrically frustrated S=(1)/(2) antiferromagnets, La 2 LiMoO 6 and Ba 2 YMoO 6 , with the B-site ordered double perovskite structure: Evidence for a collective spin-singlet ground state

Abstract: Two B-site ordered double perovskites, ${\text{La}}_{2}{\text{LiMoO}}_{6}$ and ${\text{Ba}}_{2}{\text{YMoO}}_{6}$, based on the $S=\frac{1}{2}$ ion, ${\text{Mo}}^{5+}$, have been investigated in the context of geometric magnetic frustration. Powder neutron diffraction, heat capacity, susceptibility, muon-spin relaxation $(\ensuremath{\mu}\text{SR})$, and $^{89}\text{Y}$ NMR-including magic-angle spinning (MAS) NMR data have been collected. ${\text{La}}_{2}{\text{LiMoO}}_{6}$ crystallizes in $P{2}_{1}/n$ with $a=5.59392(19)\text{ }\text{\AA{}}$, $b=5.69241(16)\text{ }\text{\AA{}}$, $c=7.88029(22)\text{ }\text{\AA{}}$, and $\ensuremath{\beta}=90.2601(30)\ifmmode^\circ\else\textdegree\fi{}$ at 299.7 K, while ${\text{Ba}}_{2}{\text{YMoO}}_{6}$ is cubic, $Fm3m$, with $a=8.39199(65)\text{ }\text{\AA{}}$ at 297.8 K. ${\text{Ba}}_{2}{\text{YMoO}}_{6}$ shows no distortion from cubic symmetry even at 2.8 K in apparent violation of the Jahn-Teller theorem for a ${t}_{2\text{g}}^{1}$ ion. $^{89}\text{Y}$ NMR MAS data indicate about a 3% level of Y/Mo site mixing. ${\text{La}}_{2}{\text{LiMoO}}_{6}$ deviates strongly from simple Curie-Weiss (C-W) paramagnetic behavior below 150 K and zero-field-cooled/field-cooled (ZFC/FC) irreversibility occurs below 20 K with a weak, broad susceptibility maximum near 5 K in the ZFC data. A Curie-Weiss fit shows a reduced ${\ensuremath{\mu}}_{\text{eff}}=1.42{\ensuremath{\mu}}_{\text{B}}$, (spin $\text{only}=1.73{\ensuremath{\mu}}_{\text{B}}$) and a Weiss temperature, ${\ensuremath{\theta}}_{\text{C}}$, which depends strongly on the temperature range of the fit. Powder neutron diffraction and heat capacity show no evidence for long-range magnetic order to 2 K. On the other hand oscillations develop below 20 K in $\ensuremath{\mu}\text{SR}$ indicating at least short-range magnetic correlations. Susceptibility data for ${\text{Ba}}_{2}{\text{YMoO}}_{6}$ also deviate strongly from the C-W law below 150 K with a nearly spin only ${\ensuremath{\mu}}_{\text{eff}}=1.72{\ensuremath{\mu}}_{\text{B}}$ and ${\ensuremath{\theta}}_{\text{C}}=\ensuremath{-}219(1)\text{ }\text{K}$. There is no discernible ZFC/FC irreversibility to 2 K. Heat capacity, neutron powder diffraction, and $\ensuremath{\mu}\text{SR}$ data show no evidence for long-range order to 2 K but a very broad, weak maximum appears in the heat capacity. The $^{89}\text{Y}$ NMR paramagnetic Knight shift shows a remarkable local spin susceptibility behavior below about 70 K with two components from roughly equal sample volumes, one indicating a singlet state and the other a strongly fluctuating paramagnetic state. Further evidence for a singlet state comes from the behavior of the relaxation rate, $1/{T}_{1}$. These results are discussed and compared with those from other isostructural $S=\frac{1}{2}$ materials and those based on $S=3/2$ and $S=1$.