3,659 research outputs found
Leaders\u2019 competence and warmth: Their relationships with employees\u2019 well-being and organizational effectiveness
The aim of this work was to investigate competence and warmth \u2014 the two basic dimensions of social judgment \u2014 as dimensions employees use to evaluate their supervisors. A mediation model was tested in which supervisor\u2019s perceived competence and warmth were associated with relevant outcomes (lower burnout, weaker turnover intentions, more frequent citizenship behaviors) through the mediation of affective organizational commitment (AOC). In Study 1, data were collected from employees of a company in the water service sector. In Study 2, participants were financial promoters. In Study 3, the sample included employees from different organizations. As hypothesized, the perception of one\u2019s supervisor as competent (Studies 1-3) and warm (Study 3) was related to employees\u2019 lower burnout, weaker turnover intentions, more frequent prosocial behaviors through the mediation of AOC. Theoretical and practical implications of findings are discussed
Inverse proximity effect at superconductor-ferromagnet interfaces: Evidence for induced triplet pairing in the superconductor
Considerable evidence for proximity-induced triplet superconductivity on the
ferromagnetic side of a superconductor-ferromagnet (S-F) interface now exists;
however, the corresponding effect on the superconductor side has hardly been
addressed. We have performed scanning tunneling spectroscopy measurements on
NbN superconducting thin films proximity coupled to the half-metallic
ferromagnet La2/3Ca1/3MnO3 (LCMO) as a function of magnetic field. We have
found that at zero and low applied magnetic fields the tunneling spectra on NbN
typically show an anomalous gap structure with suppressed coherence peaks and,
in some cases, a zero-bias conductance peak. As the field increases to the
magnetic saturation of LCMO where the magnetization is homogeneous, the spectra
become more BCS-like and the critical temperature of the NbN increases,
implying a reduced proximity effect. Our results therefore suggest that
triplet-pairing correlations are also induced in the S side of an S-F bilayer.Comment: 12 pages, 3 figure
Sliding bifurcations : a novel mechanism for the sudden onset of chaos in dry-friction oscillators
Synchronization and local convergence analysis of networks with dynamic diffusive coupling
In this paper, we address the problem of achieving synchronization in networks of nonlinear units coupled by dynamic diffusive terms. We present two types of couplings consisting of a static linear term, corresponding to the diffusive coupling, and a dynamic term which can be either the integral or the derivative of the sum of the mismatches between the states of neighbouring agents. The resulting dynamic coupling strategy is a distributed proportional-integral (PI) or a proportional-derivative (PD) law that is shown to be effective in improving the network synchronization performance, for example, when the dynamics at nodes are nonidentical. We assess the stability of the network by extending the classical Master Stability Function approach to the case where the links are dynamic ones of PI/PD type. We validate our approach via a set of representative examples including networks of chaotic Lorenz and networks of nonlinear mechanical systems
Priming attachment security and outgroup humanization: The mediation role of intergroup emotions
Individuals tend to dehumanize the outgroup. In this paper, we explore whether the activation of attachment security can attenuate dehumanization. Two studies were performed. In Study 1, attachment security was primed by showing pictures that depicted relationships with attachment figures; the outgroup was the homeless and humanization was measured considering the attribution of uniquely human and non-uniquely human emotions to this group. In Study 2, the sense of interpersonal security was activated by inviting participants to relive a recent interaction that left them with a feeling of safety and warmth. Outgroup members were the Roma, and humanization was measured considering the attribution of uniquely human and human nature traits to them. In Study 2, the mediation effect of intergroup emotions was investigated. In both studies, outgroup humanization effects were highlighted. In Study 2, these effects were mediated by increased empathy toward the outgroup. Interestingly, the positive impact of security activation was not moderated by chronic attachment orientations. Findings suggest strategies that can be used to improve intergroup relations in specific contexts and in society at large
Two-parameter nonsmooth grazing bifurcations of limit cycles: classification and open problems
This paper proposes a strategy for the classification of codimension-two grazing bifurcations of limit cycles in piecewise smooth systems of ordinary differential equations. Such nonsmooth transitions (C-bifurcations) occur when the cycle interacts with a discontinuity boundary of phase space in a non-generic way. Several such codimension-one events have recently been identified, causing for example period-adding or sudden onset of chaos. Here, the focus is on codimension-two grazings that are local in the sense that the dynamics can be fully described by an appropriate Poincaré map from a neighbourhood of the grazing point (or points) of the critical cycle to itself. It is proposed that codimension-two grazing bifurcations can be divided into three distinct types: either the grazing point is degenerate, or the the grazing cycle is itself degenerate (e.g. non-hyperbolic) or we have the simultaneous occurrence of two grazing events. A careful distinction is drawn between their occurrence in systems with discontinuous states, discontinuous vector fields, or that have discontinuity in some derivative of the vector field. Examples of each kind of bifurcation are presented, mostly derived from mechanical applications. For each example, where possible, principal bifurcation curves characteristic to the codimension-two scenario are presented and general features of the dynamics discussed. Many avenues for future research are opened.
Shrinking Point Bifurcations of Resonance Tongues for Piecewise-Smooth, Continuous Maps
Resonance tongues are mode-locking regions of parameter space in which stable
periodic solutions occur; they commonly occur, for example, near Neimark-Sacker
bifurcations. For piecewise-smooth, continuous maps these tongues typically
have a distinctive lens-chain (or sausage) shape in two-parameter bifurcation
diagrams. We give a symbolic description of a class of "rotational" periodic
solutions that display lens-chain structures for a general -dimensional map.
We then unfold the codimension-two, shrinking point bifurcation, where the
tongues have zero width. A number of codimension-one bifurcation curves emanate
from shrinking points and we determine those that form tongue boundaries.Comment: 27 pages, 6 figure
Coexisting patterns of population oscillations: the degenerate Neimark Sacker bifurcation as a generic mechanism
We investigate a population dynamics model that exhibits a Neimark Sacker
bifurcation with a period that is naturally close to 4. Beyond the bifurcation,
the period becomes soon locked at 4 due to a strong resonance, and a second
attractor of period 2 emerges, which coexists with the first attractor over a
considerable parameter range. A linear stability analysis and a numerical
investigation of the second attractor reveal that the bifurcations producing
the second attractor occur naturally in this type of system.Comment: 8 pages, 3 figure
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