3,084 research outputs found
Environment of compact extragalactic radio sources
We have studied the interrelation of young AGN with their hosts. The objects
of study are the young and powerful GPS and CSS radio sources. Due to their
small size, GPS and CSS sources are excellent probes of this relation.
Furhthermore, their young age allows us to compare them to the larger, old
radio sources and establish a time-line evolution of this relation. Combining
imaging and spectroscopy at UV, optical and radio wavelengths we find evidence
of strong interaction between the host and the radio source. The presence and
expansion of the radio source clearly affects the properties and evolution of
the host. Furthermore, the radio source and host significantly affect each
other's evolution. We describe our results and how these interactions take
place.Comment: 6 pages. To appear in "Highlights of Spanisg astrophysics IV.
Proceedings of the VII scientific meeting of the Spanish Astronomical
Society". Editors: F. Figueras, J.M. Girart, M.Hernanz, C. Jordi. Springe
Are forgiving people less likely to experience cognitive dissonance?
People differ in the degree to which they are able and willing to forgive themselves after they have committed a transgression against another person (Thompson et al., 2005). The purpose of the current study was to see if individuals with lower levels of dispositional forgiveness would experience more attitude change toward a boring task than those who have higher levels of dispositional forgiveness, as a result of cognitive dissonance being induced. Participants completed a boring task that involved moving beads back and forth on an abacus, and then were either asked or told to mislead the next participant by telling them that the task was enjoyable in order to induce cognitive dissonance in the participant. They were then asked to complete a questionnaire designed to measure their attitudes toward the abacus task. It was predicted that the participants with lower levels of dispositional forgiveness would end with more positive attitudes toward the abacus task than those with higher levels of dispositional forgiveness. The study did not yield any statistically significant results. The limitations of the study will be discussed
Realistic theory of electronic correlations in nanoscopic systems
Nanostructures with open shell transition metal or molecular constituents
host often strong electronic correlations and are highly sensitive to atomistic
material details. This tutorial review discusses method developments and
applications of theoretical approaches for the realistic description of the
electronic and magnetic properties of nanostructures with correlated electrons.
First, the implementation of a flexible interface between density functional
theory and a variant of dynamical mean field theory (DMFT) highly suitable for
the simulation of complex correlated structures is explained and illustrated.
On the DMFT side, this interface is largely based on recent developments of
quantum Monte Carlo and exact diagonalization techniques allowing for efficient
descriptions of general four fermion Coulomb interactions, reduced symmetries
and spin-orbit coupling, which are explained here. With the examples of the Cr
(001) surfaces, magnetic adatoms, and molecular systems it is shown how the
interplay of Hubbard U and Hund's J determines charge and spin fluctuations and
how these interactions drive different sorts of correlation effects in
nanosystems. Non-local interactions and correlations present a particular
challenge for the theory of low dimensional systems. We present our method
developments addressing these two challenges, i.e., advancements of the
dynamical vertex approximation and a combination of the constrained random
phase approximation with continuum medium theories. We demonstrate how
non-local interaction and correlation phenomena are controlled not only by
dimensionality but also by coupling to the environment which is typically
important for determining the physics of nanosystems.Comment: tutorial review submitted to EPJ-ST (scientific report of research
unit FOR 1346); 14 figures, 26 page
Interlaced Dynamical Decoupling and Coherent Operation of a Singlet-Triplet Qubit
We experimentally demonstrate coherence recovery of singlet-triplet
superpositions by interlacing qubit rotations between Carr-Purcell (CP) echo
sequences. We then compare performance of Hahn, CP, concatenated dynamical
decoupling (CDD) and Uhrig dynamical decoupling (UDD) for singlet recovery. In
the present case, where gate noise and drift combined with spatially varying
hyperfine coupling contribute significantly to dephasing, and pulses have
limited bandwidth, CP and CDD yield comparable results, with T2 ~ 80
microseconds.Comment: related papers at http://marcuslab.harvard.ed
Rapid Single-Shot Measurement of a Singlet-Triplet Qubit
We report repeated single-shot measurements of the two-electron spin state in
a GaAs double quantum dot. The readout scheme allows measurement with fidelity
above 90% with a 7 microsecond cycle time. Hyperfine-induced precession between
singlet and triplet states of the two-electron system are directly observed, as
nuclear Overhauser fields are quasi-static on the time scale of the measurement
cycle. Repeated measurements on millisecond to second time scales reveal
evolution of the nuclear environment.Comment: supplemental material at
http://marcuslab.harvard.edu/papers/single_shot_sup.pd
Hyperfine-mediated gate-driven electron spin resonance
An all-electrical spin resonance effect in a GaAs few-electron double quantum
dot is investigated experimentally and theoretically. The magnetic field
dependence and absence of associated Rabi oscillations are consistent with a
novel hyperfine mechanism. The resonant frequency is sensitive to the
instantaneous hyperfine effective field, and the effect can be used to detect
and create sizable nuclear polarizations. A device incorporating a micromagnet
exhibits a magnetic field difference between dots, allowing electrons in either
dot to be addressed selectively.Comment: related papers available at http://marcuslab.harvard.ed
Many-body effects on Cr(001) surfaces: An LDA+DMFT study
The electronic structure of the Cr(001) surface with its sharp resonance at
the Fermi level is a subject of controversial debate of many experimental and
theoretical works. To date, it is unclear whether the origin of this resonance
is an orbital Kondo or an electron-phonon coupling effect. We have combined ab
initio density functional calculations with dynamical mean-field simulations to
calculate the orbitally resolved spectral function of the Cr(001) surface. The
calculated orbital character and shape of the spectrum is in agreement with
data from (inverse) photoemission experiments. We find that dynamic electron
correlations crucially influence the surface electronic structure and lead to a
low energy resonance in the and orbitals. Our results
help to reconvene controversial experimental results from (I)PES and STM
measurements.Comment: 8 pages, 5 figure
Next speakers plan their turn early and speak after turn-final ‘go-signals’
In conversation, turn-taking is usually fluid, with next speakers taking their turn right after the end of the previous turn. Most, but not all, previous studies show that next speakers start to plan their turn early, if possible already during the incoming turn. The present study makes use of the list-completion paradigm (Barthel et al., 2016), analyzing speech onset latencies and eye-movements of participants in a task-oriented dialogue with a confederate. The measures are used to disentangle the contributions to the timing of turn-taking of early planning of content on the one hand and initiation of articulation as a reaction to the upcoming turn-end on the other hand. Participants named objects visible on their computer screen in response to utterances that did, or did not, contain lexical and prosodic cues to the end of the incoming turn. In the presence of an early lexical cue, participants showed earlier gaze shifts toward the target objects and responded faster than in its absence, whereas the presence of a late intonational cue only led to faster response times and did not affect the timing of participants' eye movements. The results show that with a combination of eye-movement and turn-transition time measures it is possible to tease apart the effects of early planning and response initiation on turn timing. They are consistent with models of turn-taking that assume that next speakers (a) start planning their response as soon as the incoming turn's message can be understood and (b) monitor the incoming turn for cues to turn-completion so as to initiate their response when turn-transition becomes relevan
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