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Universal distributions from non-Hermitian perturbation of zero modes. Phys Rev E 2020; 101:032117. [PMID: 32289952 DOI: 10.1103/physreve.101.032117] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Accepted: 02/14/2020] [Indexed: 11/07/2022]
Abstract
Hermitian operators with exact zero modes subject to non-Hermitian perturbations are considered. Specific focus is on the distribution of the former zero eigenvalues of the Hermitian operators. The broadening of these zero modes is found to follow an elliptic Gaussian random matrix ensemble of fixed size, where the symmetry class of the perturbation determines the behavior of the modes. This distribution follows from a central limit theorem of matrices and is shown to be robust to deformations.
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Abstract
AbstractIn-group cohesion is an essential component of successful intergroup competition in both human and nonhuman animals, likely facilitating group members access to potential benefits. However, when benefits are equally shared among group members, group defense becomes a collective action problem, which might subvert cohesive participation during intergroup competition. There is a lack of consensus across studies and species with regard to the link between in-group cohesion and intergroup competition, likely as a result of species differences in managing the collective action problem. Here, we examine this link in a species with a striking example of collective action during intergroup competition, chimpanzees (Pan troglodytes verus). Using two years of focal-follow data on males and females in two groups at the Taï Forest, Côte d’Ivoire, we investigated the immediate and long-term effects of intergroup competition (border patrols and intergroup encounters) on measures of in-group cohesion, namely modularity, party size, and intergroup aggression. We found that groups’ association patterns were less modular (more cohesive) in months in which they engaged in more border patrols and intergroup encounters. We found that current and greater prior engagement in intergroup competition predicted larger party sizes. Furthermore, current, but not prior engagement in intergroup competition, predicted reduced intragroup aggression by males but not by females. Increased in-group cohesion in chimpanzees likely reduces potential costs of intergroup competition engagement, by facilitating joint participation in current and future intergroup conflicts, overcoming the collective action problem.
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Universal broadening of zero modes: A general framework and identification. Phys Rev E 2019; 99:052112. [PMID: 31212564 DOI: 10.1103/physreve.99.052112] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Indexed: 11/07/2022]
Abstract
We consider the smallest eigenvalues of perturbed Hermitian operators with zero modes, either topological or system specific. To leading order for small generic perturbation we show that the corresponding eigenvalues broaden to a Gaussian random matrix ensemble of size ν×ν, where ν is the number of zero modes. This observation unifies and extends a number of results within chiral random matrix theory and effective field theory and clarifies under which conditions they apply. The scaling of the former zero modes with the volume differs from the eigenvalues in the bulk, which we propose as an indicator to identify them in experiments. These results hold for all 10 symmetric spaces in the Altland-Zirnbauer classification and build on two facts. First, the broadened zero modes decouple from the bulk eigenvalues and, second, the mixing from eigenstates of the perturbation form a central limit theorem argument for matrices.
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Social bonds facilitate cooperative resource sharing in wild chimpanzees. Proc Biol Sci 2018; 285:rspb.2018.1643. [PMID: 30305438 DOI: 10.1098/rspb.2018.1643] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Accepted: 09/20/2018] [Indexed: 11/12/2022] Open
Abstract
Why share when access to benefits is uncertain is crucial to our understanding of the evolution of humans' extensive cooperation. Here, we investigated some of the different human sharing hypotheses and potential neuroendocrine mechanisms, in one of our closest living relatives, chimpanzees. The strongest predictor of sharing across food types was the presence of enduring and mutually preferred grooming partners, more than harassment, direct signalling, or trade. Moreover, urinary oxytocin levels were higher after the sharing of both individually and jointly acquired resources compared with controls. We conclude that the emotional connection inherent in social bonds was a key factor determining sharing patterns, with the oxytocinergic system potentially facilitating long-term cooperative exchanges. Testing for the role of social bonds in increasing predictability of sharing behaviour, a feature frequently overlooked, may help us to identify the evolutionary drivers of resource sharing and mechanisms that sustain delayed reciprocity between non-kin.
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Urinary oxytocin levels in relation to post-conflict affiliations in wild male chimpanzees (Pan troglodytes verus). Horm Behav 2018; 105:28-40. [PMID: 30031684 DOI: 10.1016/j.yhbeh.2018.07.009] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Revised: 07/17/2018] [Accepted: 07/18/2018] [Indexed: 01/03/2023]
Abstract
Many animals living in social groups have evolved behaviors to resolve conflicts between group members, behaviors thought crucial for maintaining stable group life. Several hypotheses, based mainly on observational data, aim to explain how post-conflict (PC) affiliations, such as reconciliation and consolation, resolve conflicts by restoring relationships and/or alleviating anxiety. To examine a potential endocrinological mechanism of PC affiliations, we used an experimental-like procedure to investigate whether the oxytocinergic system is activated during naturally observed reconciliations, receiving bystander PC affiliations and aggressions not followed by PC affiliations in wild male chimpanzees. We compared urinary oxytocin (uOT) levels after reconciliations, receiving bystander PC affiliations or aggressions without affiliations with two control conditions: affiliations without previous aggression and after time periods without social interactions. We furthermore tested the 'valuable relationship' hypothesis of reconciliation, as well as the influence of relationship quality between individuals engaged in each of the three behavioral conditions involving aggression on uOT levels. We found that the probability to reconcile a conflict increased with increasing relationship quality between opponents, thus our results support the 'valuable relationship' hypothesis. However, relationship quality did not influence uOT levels, while behavioral condition had a significant effect on uOT levels. uOT levels after reconciliations, receiving bystander PC affiliations and affiliations not related to conflicts were higher than after aggressions alone and time periods without social interactions. Overall, our results indicate that the oxytocinergic system is activated during affiliative interactions, whether occurring as reconciliation, bystander PC affiliation or affiliation alone. We conclude that the oxytocinergic system, in addition to building and maintaining social relationships, also takes part in repairing them.
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[The influence of visual rehabilitation on secondary depressive disorders due to age-related macular degeneration. A randomized controlled pilot study]. Ophthalmologe 2013; 110:433-40. [PMID: 23380979 DOI: 10.1007/s00347-012-2715-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
BACKGROUND Age-related macular degeneration (AMD) often leads to visual impairment, loss of reading ability, reduced quality of life and secondary depression. The present study examined if visual rehabilitation has a preventive effect on secondary depression in these patients. MATERIAL AND METHODS In a controlled pilot study 20 patients were randomized into 2 groups whereby 9 underwent visual rehabilitation at first examination and 11 received magnifying visual aids only after 3 months. Psychosocial status was assessed by the geriatric depression scale (GDS) and the German version of the Centre for Epidemiologic Studies depression (CES-D) scale (main outcome parameter), cognitive status by the dementia detection test (DemTecT), minimental status (MMS) and quality of life by the National Eye Institute visual function questionnaire (NEI-VFQ 25). Ophthalmological examination included reading speed measurement by standardized texts (International Reading Speed Texts; IReST). RESULTS Parameters of the CES-D scale, DemTect and the subitem exercise of social roles of the NEI-VFQ 25 emerged in a divergent manner. Patients of the rehabilitation group became less depressive and improved in cognitive and social abilities and in the control group vice versa. The interactive effect of group and time was statistically significant for all three tests. CONCLUSIONS Visual rehabilitation has a positive impact on depression as well as cognitive status and quality of life in patients with AMD. The effects have to be confirmed in future studies with more patients and a longer observation period.
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Hantavirusassoziiertes Guillain-Barré-Syndrom. AKTUELLE NEUROLOGIE 2011. [DOI: 10.1055/s-0030-1266147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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First Experiences with a New Device for Mechanical Thrombectomy in Acute Basilar Artery Occlusion. Cerebrovasc Dis 2011; 32:28-34. [DOI: 10.1159/000324948] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2010] [Accepted: 02/07/2011] [Indexed: 11/19/2022] Open
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Unterdrucklungenödem nach Allgemeinanästhesie. Anaesthesist 2008; 57:359-63. [DOI: 10.1007/s00101-007-1256-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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On the possible relationship between staphylococcal superantigens and increased Vbeta5.1 usage in cutaneous T-cell lymphoma: reply from authors. Br J Dermatol 2005. [DOI: 10.1111/j.1365-2133.2005.06523.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Polyclonal expansion of T cells with the TCR Vbeta type of the tumour cell in lesions of cutaneous T-cell lymphoma: evidence for possible superantigen involvement. Br J Dermatol 2004; 150:1013-7. [PMID: 15149519 DOI: 10.1111/j.1365-2133.2004.05970.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The involvement of superantigens in the pathology of cutaneous T-cell lymphomas (CTCL) has been suggested before, but without unequivocal evidence for superantigen activity in the patients. Seeking evidence for superantigen activity we analysed clones and microdissected single cells isolated from the epidermis of early-stage lesions of a CTCL patient for their T-cell receptor (TCR) V beta expression and TCR V gamma gene rearrangements. The vast majority of these T cells expressed the TCR V beta family type of the tumour. From their TCR gamma gene rearrangements, however, these cells were polyclonal. The tumour cell clone accounted for about 60% of these cells, about 40% were of heterogeneous origin. This dominance of a single V beta family in the polyclonally expanded dermal T-cell populations implies superantigen activity in the CTCL lesions.
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Flow equations for Hamiltonians: contrasting different approaches by using a numerically solvable model. ACTA ACUST UNITED AC 2003. [DOI: 10.1088/0305-4470/36/11/305] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Evolution of Rate-Independent Inelasticity with Microstructure using Relaxation and Young Measures. IUTAM SYMPOSIUM ON COMPUTATIONAL MECHANICS OF SOLID MATERIALS AT LARGE STRAINS 2003. [DOI: 10.1007/978-94-017-0297-3_3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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A new identity for the surface–impedance matrix and its application to the determination of surface-wave speeds. Proc Math Phys Eng Sci 2002. [DOI: 10.1098/rspa.2002.1000] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Effective rate equations for the overdamped motion in fluctuating potentials. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2001; 64:021106. [PMID: 11497561 DOI: 10.1103/physreve.64.021106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2000] [Indexed: 05/23/2023]
Abstract
We discuss physical and mathematical aspects of the overdamped motion of a Brownian particle in fluctuating potentials. It is shown that such a system can be described quantitatively by fluctuating rates if the potential fluctuations are slow compared to relaxation within the minima of the potential, and if the position of the minima does not fluctuate. Effective rates can be calculated; they describe the long-time dynamics of the system. Furthermore, we show the existence of a stationary solution of the Fokker-Planck equation that describes the motion within the fluctuating potential under some general conditions. We also show that a stationary solution of the rate equations with fluctuating rates exists.
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Noise-induced transport of two coupled particles. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2001; 63:031914. [PMID: 11308685 DOI: 10.1103/physreve.63.031914] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2000] [Revised: 08/17/2000] [Indexed: 05/23/2023]
Abstract
We study the motion of two harmonically coupled particles in a sawtooth potential. The particles are subject to temporally correlated multiplicative noise. The stationary current is calculated in an expansion about the limit of rigid coupling. For two coupled particles a driving mechanism occurs which is different from the one occurring in the case of a single particle. In particular this mechanism does not need diffusion. Depending on the equilibrium distance of the particles and the coupling constant, a current reversal occurs. Possible relevance as a model for motor proteins is discussed.
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Noise induced stability in fluctuating, bistable potentials. PHYSICAL REVIEW LETTERS 2000; 84:818-821. [PMID: 11017381 DOI: 10.1103/physrevlett.84.818] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/1999] [Indexed: 05/23/2023]
Abstract
The overdamped motion of a Brownian particle in an asymmetric, bistable, fluctuating potential shows noise induced stability: For intermediate fluctuation rates the mean occupancy of minima with an energy above the absolute minimum is enhanced. The model works as a detector for potential fluctuations being not too fast and not too slow. This effect occurs due to the different time scales in the problem. We present a detailed analysis of this effect using the exact solution of the Fokker-Planck equation for a simple model. Further we show that for not too fast fluctuations the system can be well described by effective rate equations. The results of the rate equations agree quantitatively with the exact results.
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Identification of epitopes for CTCL-specific cytotoxic T lymphocytes. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1999; 451:231-5. [PMID: 10026877 DOI: 10.1007/978-1-4615-5357-1_36] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
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Transition from superconductivity to heavy-fermion behavior in U-doped Lu2Fe3Si5. PHYSICAL REVIEW. B, CONDENSED MATTER 1994; 50:16522-16527. [PMID: 9976039 DOI: 10.1103/physrevb.50.16522] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Important role of coherence for the heavy-fermion state in CeCu2Si2. PHYSICAL REVIEW. B, CONDENSED MATTER 1994; 49:10051-10053. [PMID: 10009823 DOI: 10.1103/physrevb.49.10051] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Influence of hybridization and actinide spacing in U2Ptx(Os,Ir)1-xC2 systems. PHYSICAL REVIEW. B, CONDENSED MATTER 1994; 49:1188-1191. [PMID: 10010425 DOI: 10.1103/physrevb.49.1188] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Specific heat of CePtSi in a high magnetic field. PHYSICAL REVIEW. B, CONDENSED MATTER 1993; 48:13985-13986. [PMID: 10007802 DOI: 10.1103/physrevb.48.13985] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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