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Search Results: 1 - 10 of 418451 matches for " Alexander M. Rapp "
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Irony and Proverb Comprehension in Schizophrenia: Do Female Patients “Dislike” Ironic Remarks?
Alexander M. Rapp,Karin Langohr,Dorothee E. Mutschler,Barbara Wild
Schizophrenia Research and Treatment , 2014, DOI: 10.1155/2014/841086
Abstract: Difficulties in understanding irony and sarcasm are part of the social cognition deficits in patients with schizophrenia. A number of studies have reported higher error rates during comprehension in patients with schizophrenia. However, the relationships of these impairments to schizotypal personality traits and other language deficits, such as the comprehension of proverbs, are unclear. We investigated irony and proverb comprehension in an all-female sample of 20 schizophrenia patients and 27 matched controls. Subjects indicated if a statement was intended to be ironic, literal, or meaningless and furthermore rated the meanness and funniness of the stimuli and certainty of their decision. Patients made significantly more errors than controls did. Globally, there were no overall differences in the ratings. However, patients rated the subgroup of stimuli with answers given incorrectly as having significantly less meanness and in case of an error indicated a significantly higher certainty than controls. Across all of the study participants, performances in irony ( ) and proverb ( ) comprehension were significantly correlated with schizotypal personality traits, suggesting a continuum of nonliteral language understanding. Because irony is so frequent in everyday conversations, this makes irony an especially promising candidate for social cognition training in schizophrenia. 1. Background Defective appraisal of the intention of others and difficulties with language are hallmark features of psychopathology in schizophrenia. Social cognition deficits have been previously identified and are currently being extensively researched. The results show that deficits in social cognition are relevant to real-world functioning and outcome [1]. Training of social cognitive skills has gained increasing interest in schizophrenia therapy. In this context, the comprehension of ironic remarks by patients with schizophrenia has become a research focus both as an outcome measure and as a training goal [1–5]. This is obvious, considering that the decision on whether a remark made by others is intended to be ironic or not is slightly artificial, but is instead required routinely in everyday interaction. Everyone is familiar with irony. It is remarkably frequently used, as shown by linguistic research [6, 7]. For example, Gibbs [8] showed that 1 out of 8 conversational turns in an everyday communication among college students was ironic. In the case of linguistic irony (which alone is discussed here), an ironic expression is usually incorrect and often the opposite of what the
Isn’t it ironic? Neural Correlates of Irony Comprehension in Schizophrenia
Alexander M. Rapp, Karin Langohr, Dorothee E. Mutschler, Stefan Klingberg, Barbara Wild, Michael Erb
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0074224
Abstract: Ironic remarks are frequent in everyday language and represent an important form of social cognition. Increasing evidence indicates a deficit in comprehension in schizophrenia. Several models for defective comprehension have been proposed, including possible roles of the medial prefrontal lobe, default mode network, inferior frontal gyri, mirror neurons, right cerebral hemisphere and a possible mediating role of schizotypal personality traits. We investigated the neural correlates of irony comprehension in schizophrenia by using event-related functional magnetic resonance imaging (fMRI). In a prosody-free reading paradigm, 15 female patients with schizophrenia and 15 healthy female controls silently read ironic and literal text vignettes during fMRI. Each text vignette ended in either an ironic (n = 22) or literal (n = 22) statement. Ironic and literal text vignettes were matched for word frequency, length, grammatical complexity, and syntax. After fMRI, the subjects performed an off-line test to detect error rate. In this test, the subjects indicated by button press whether the target sentence has ironic, literal, or meaningless content. Schizotypal personality traits were assessed using the German version of the schizotypal personality questionnaire (SPQ). Patients with schizophrenia made significantly more errors than did the controls (correct answers, 85.3% vs. 96.3%) on a behavioural level. Patients showed attenuated blood oxygen level-dependent (BOLD) response during irony comprehension mainly in right hemisphere temporal regions (ironic>literal contrast) and in posterior medial prefrontal and left anterior insula regions (for ironic>visual baseline, but not for literal>visual baseline). In patients with schizophrenia, the parahippocampal gyrus showed increased activation. Across all subjects, BOLD response in the medial prefrontal area was negatively correlated with the SPQ score. These results highlight the role of the posterior medial prefrontal and right temporal regions in defective irony comprehension in schizophrenia and the mediating role of schizotypal personality traits.
Charging of mesospheric aerosol particles: the role of photodetachment and photoionization from meteoric smoke and ice particles
M. Rapp
Annales Geophysicae (ANGEO) , 2009,
Abstract: Time constants for photodetachment, photoemission, and electron capture are considered for two classes of mesospheric aerosol particles, i.e., meteor smoke particles (MSPs) and pure water ice particles. Assuming that MSPs consist of metal oxides like Fe2O3 or SiO, we find that during daytime conditions photodetachment by solar photons is up to 4 orders of magnitude faster than electron attachment such that MSPs cannot be negatively charged in the presence of sunlight. Rather, even photoemission can compete with electron capture unless the electron density becomes very large (>>1000 cm 3) such that MSPs should either be positively charged or neutral in the case of large electron densities. For pure water ice particles, however, both photodetachment and photoemission are negligible due to the wavelength characteristics of its absorption cross section and because the flux of solar photons has already dropped significantly at such short wavelengths. This means that water ice particles should normally be negatively charged. Hence, our results can readily explain the repeated observation of the coexistence of positive and negative aerosol particles in the polar summer mesopause, i.e., small MSPs should be positively charged and ice particles should be negatively charged. These results have further important implications for our understanding of the nucleation of mesospheric ice particles as well as for the interpretation of incoherent scatter radar observations of MSPs.
Statistical characteristics of PMWE observations by the EISCAT VHF radar
I. Strelnikova,M. Rapp
Annales Geophysicae (ANGEO) , 2013,
Abstract: In the present paper ~ 32.5 h of EISCAT VHF PMWE observations were analyzed with focus on spectral properties like spectral width, doppler shift and spectral shape. Examples from two days of observations with weak and strong polar mesosphere winter echo (PMWE) signals are presented and discussed in detail. These examples reveal a large variability from one case to the other. That is, some features like an observed change of vertical wind direction and spectral broadening can be very prominent in one case, but unnoticeable in the other case. However, for all observations a change of spectral shape inside the layer relative to the incoherent background is noticed.
Hadronic Modes and Quark Properties in the Quark-Gluon Plasma
M. Mannarelli,R. Rapp
Physics , 2005, DOI: 10.1103/PhysRevC.72.064905
Abstract: Based on interaction potentials between a heavy quark and antiquark as extracted from recent QCD lattice calculations, we set up a Brueckner-type many-body scheme to study the properties of light (anti-) quarks in a Quark-Gluon Plasma at moderate temperatures, $T\simeq$ 1-2 $T_c$. The quark-antiquark $T$-matrix, including both color-singlet and -octet channels, and corresponding quark self-energies and spectral functions are calculated self-consistently. The repulsive octet potential induces quasiparticle masses of up to 150 MeV, whereas the attractive color-singlet part generates resonance structures in the $q$-$\bar q$ $T$-matrix, which in turn lead to quasiparticle widths of $\sim$200 MeV. This corresponds to scattering rates of $\sim$1 fm$^{-1}$ and may reflect liquid-like properties of the system.
Evaluating chiral symmetry restoration through the use of sum rules
Hohler Paul M.,Rapp Ralf
EPJ Web of Conferences , 2012, DOI: 10.1051/epjconf/20123600012
Abstract: We pursue the idea of assessing chiral restoration via in-medium modifications of hadronic spectral functions of chiral partners. The usefulness of sum rules in this endeavor is illustrated, focusing on the vector/axial-vector channel. We first present an update on obtaining quantitative results for pertinent vacuum spectral functions. These serve as a basis upon which the in-medium spectral functions can be constructed. A novel feature of our analysis of the vacuum spectral functions is the need to include excited resonances, dictated by satisfying the Weinberg-type sum rules. This includes excited states in both the vector and axial-vector channels.We also analyze the QCD sum rule for the finite temperature vector spectral function, based on a ρ spectral function tested in dilepton data which develops a shoulder at low energies.We find that the ρ′ peak flattens off which may be a sign of chiral restoration, though a study of the finite temperature axial-vector spectral function remains to be carried out.
Sum rule analysis of vector and axial-vector spectral functions with excited states in vacuum
Paul M. Hohler,Ralf Rapp
Physics , 2012, DOI: 10.1016/j.nuclphysa.2012.08.003
Abstract: We simultaneously analyze vector and axial-vector spectral functions in vacuum using hadronic models constrained by experimental data and the requirement that Weinberg-type sum rules are satisfied. Upon explicit inclusion of an excited vector state, viz. rho', and the requirement that the perturbative continua are degenerate in vector and axial-vector channels, we deduce the existence of an excited axial-vector resonance state, a1', in order that the Weinberg sum rules are satisfied. The resulting spectral functions are further tested with QCD sum rules.
Realistic Implementation of Massive Yang Mills for rho and a1 Mesons
Paul M. Hohler,Ralf Rapp
Physics , 2013, DOI: 10.1103/PhysRevD.89.125013
Abstract: We revisit the massive Yang-Mills approach to implement axial-/vector mesons into the chiral pion Lagrangian. Employing the non-linear realization of chiral symmetry, we compute vector and axial-vector spectral functions. This includes, for the first time, a resummation of the $\rho$ propagator in the $a_1$ selfenergy while maintaining a partially conserved axial-vector current (PCAC). A realistic $\rho$ propagator, combined with a recent idea of a chirally invariant continuum in the vector and axial-vector channels, turns out be critical to obtain a quantitative description of hadronic $\tau$-decay data which has not been achieved before in local-gauge approaches to the chiral lagrangian. The thus obtained model provides a realistic basis to rigorously address the long-standing question of chiral symmetry restoration in the context of dilepton data in heavy-ion collisions.
Is Rho-Meson Melting Compatible with Chiral Restoration?
Paul M. Hohler,Ralf Rapp
Physics , 2013, DOI: 10.1016/j.physletb.2014.02.021
Abstract: Utilizing in-medium vector spectral functions which describe dilepton data in ultra-relativistic heavy-ion collisions, we conduct a comprehensive evaluation of QCD and Weinberg sum rules at finite temperature. The starting point is our recent study in vacuum, where the sum rules have been quantitatively satisfied using phenomenological axial-/vector spectral functions which describe hadronic tau-decay data. In the medium, the temperature dependence of condensates and chiral order parameters is taken from thermal lattice QCD where available, and otherwise estimated from a hadron resonance gas. Since little is known about the in-medium axial-vector spectral function, we model it with a Breit-Wigner ansatz allowing for smooth temperature variations of its width and mass parameters. Our study thus amounts to testing the compatibility of the $\rho$-broadening found in dilepton experiments with (the approach toward) chiral restoration, and thereby searching for viable in-medium axial-vector spectral functions.
Dileptons and Chiral Symmetry Restoration
P. M. Hohler,R. Rapp
Physics , 2015,
Abstract: We report on recent work relating the medium effects observed in dilepton spectra in heavy-ion collisions to potential signals of chiral symmetry restoration. The key connection remains the approach to spectral function degeneracy between the vector-isovector channel with its chiral partner, the axialvector-isovector channel. Several approaches are discussed to elaborate this connection, namely QCD and Weinberg sum rules with input for chiral order parameters from lattice QCD, and chiral hadronic theory to directly evaluate the medium effects of the axialvector channel and the pertinent pion decay constant as function of temperature. A pattern emerges where the chiral mass splitting between rho and a_1 burns off and is accompanied by a strong broadening of the spectral distributions.
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