409 research outputs found
Humor in psychiatry: Lessons from neuroscience, psychopathology, and treatment research
Humor is a ubiquitous human characteristic that is socially motivated at its core and has a broad range of significant positive effects on emotional well-being and interpersonal relationships. Simultaneously, however, impairments in humor abilities have often been described in close association with the occurrence and course of neuropsychiatric disorders, such as schizophrenia, social anxiety, or depression. In the past decade, research in the neuroimaging and psychiatric domain has substantially progressed to (i) characterize impaired humor as an element of psychopathology, and (ii) shed light on the neurobiological mechanisms underlying the role of humor in neuropsychiatric diseases. However, (iii) targeted interventions using concepts of positive psychology have revealed first evidence that a systematic training and/or a potential reactivation of humor-related skills can improve rehabilitative outcome in neuropsychiatric patient groups. Here, we sought to integrate evidence from neuroscience, as well as from psychopathology and treatment research to shed more light on the role of humor in psychiatry. Based on these considerations, we provide directions for future research and application in mental health services, focusing on the question of how our scientific understanding of humor can provide the basis for psychological interventions that foster positive attitudes and well-being
Comparing lattice Dirac operators with Random Matrix Theory
We study the eigenvalue spectrum of different lattice Dirac operators
(staggered, fixed point, overlap) and discuss their dependence on the
topological sectors. Although the model is 2D (the Schwinger model with
massless fermions) our observations indicate possible problems in 4D
applications. In particular misidentification of the smallest eigenvalues due
to non-identification of the topological sector may hinder successful
comparison with Random Matrix Theory (RMT).Comment: LATTICE99(topology and confinement), Latex2e using espcrc2.sty, 3
pages, 3 figure
Antagonism between brain regions relevant for cognitive control and emotional memory facilitates the generation of humorous ideas
The ability to generate humor gives rise to positive emotions and thus facilitate the successful resolution of adversity. Although there is consensus that inhibitory processes might be related to broaden the way of thinking, the neural underpinnings of these mechanisms are largely unknown. Here, we use functional Magnetic Resonance Imaging, a humorous alternative uses task and a stroop task, to investigate the brain mechanisms underlying the emergence of humorous ideas in 24 subjects. Neuroimaging results indicate that greater cognitive control abilities are associated with increased activation in the amygdala, the hippocampus and the superior and medial frontal gyrus during the generation of humorous ideas. Examining the neural mechanisms more closely shows that the hypoactivation of frontal brain regions is associated with an hyperactivation in the amygdala and vice versa. This antagonistic connectivity is concurrently linked with an increased number of humorous ideas and enhanced amygdala responses during the task. Our data therefore suggests that a neural antagonism previously related to the emergence and regulation of negative affective responses, is linked with the generation of emotionally positive ideas and may represent an important neural pathway supporting mental health
Statistical analysis and the equivalent of a Thouless energy in lattice QCD Dirac spectra
Random Matrix Theory (RMT) is a powerful statistical tool to model spectral
fluctuations. This approach has also found fruitful application in Quantum
Chromodynamics (QCD). Importantly, RMT provides very efficient means to
separate different scales in the spectral fluctuations. We try to identify the
equivalent of a Thouless energy in complete spectra of the QCD Dirac operator
for staggered fermions from SU(2) lattice gauge theory for different lattice
size and gauge couplings. In disordered systems, the Thouless energy sets the
universal scale for which RMT applies. This relates to recent theoretical
studies which suggest a strong analogy between QCD and disordered systems. The
wealth of data allows us to analyze several statistical measures in the bulk of
the spectrum with high quality. We find deviations which allows us to give an
estimate for this universal scale. Other deviations than these are seen whose
possible origin is discussed. Moreover, we work out higher order correlators as
well, in particular three--point correlation functions.Comment: 24 pages, 24 figures, all included except one figure, missing eps
file available at http://pluto.mpi-hd.mpg.de/~wilke/diff3.eps.gz, revised
version, to appear in PRD, minor modifications and corrected typos, Fig.4
revise
Spectrum of the fixed point Dirac operator in the Schwinger model
Recently, properties of the fixed point action for fermion theories have been
pointed out indicating realization of chiral symmetry on the lattice. We check
these properties by numerical analysis of the spectrum of a parametrized fixed
point Dirac operator investigating also microscopic fluctuations and fermion
condensation.Comment: LATTICE98(improvement), 3 pages, 3 figure
Propagation losses in photonic crystal waveguides: Effects of band tail absorption and waveguide dispersion
Fake symmetry transitions in lattice Dirac spectra
In a recent lattice investigation of Ginsparg-Wilson-type Dirac operators in
the Schwinger model, it was found that the symmetry class of the random matrix
theory describing the small Dirac eigenvalues appeared to change from the
unitary to the symplectic case as a function of lattice size and coupling
constant. We present a natural explanation for this observation in the
framework of a random matrix model, showing that the apparent change is caused
by the onset of chiral symmetry restoration in a finite volume. A transition
from unitary to symplectic symmetry does not occur.Comment: 6 pages, 3 figures, REVTe
Spectrum of the U(1) staggered Dirac operator in four dimensions
We compare the low-lying spectrum of the staggered Dirac operator in the
confining phase of compact U(1) gauge theory on the lattice to predictions of
chiral random matrix theory. The small eigenvalues contribute to the chiral
condensate similar as for the SU(2) and SU(3) gauge groups. Agreement with the
chiral unitary ensemble is observed below the Thouless energy, which is
extracted from the data and found to scale with the lattice size according to
theoretical predictions.Comment: 5 pages, 3 figure
Universal Scaling of the Chiral Condensate in Finite-Volume Gauge Theories
We confront exact analytical predictions for the finite-volume scaling of the
chiral condensate with data from quenched lattice gauge theory simulations.
Using staggered fermions in both the fundamental and adjoint representations,
and gauge groups SU(2) and SU(3), we are able to test simultaneously all of the
three chiral universality classes. With overlap fermions we also test the
predictions for gauge field sectors of non-zero topological charge. Excellent
agreement is found in most cases, and the deviations are understood in the
others.Comment: Expanded discussion of overlap fermion results. 17 pages revtex, 7
postscript figure
Staggered Fermions and Gauge Field Topology
Based on a large number of smearing steps, we classify SU(3) gauge field
configurations in different topological sectors. For each sector we compare the
exact analytical predictions for the microscopic Dirac operator spectrum of
quenched staggered fermions. In all sectors we find perfect agreement with the
predictions for the sector of topological charge zero, showing explicitly that
the smallest Dirac operator eigenvalues of staggered fermions at presently
realistic lattice couplings are insensitive to gauge field topology. On the
smeared configurations, eigenvalues clearly separate out from the rest
on configurations of topological charge , and move towards zero in
agreement with the index theorem.Comment: LaTeX, 10 page
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