708 research outputs found
Eigenstate Structure in Graphs and Disordered Lattices
We study wave function structure for quantum graphs in the chaotic and
disordered regime, using measures such as the wave function intensity
distribution and the inverse participation ratio. The result is much less
ergodicity than expected from random matrix theory, even though the spectral
statistics are in agreement with random matrix predictions. Instead, analytical
calculations based on short-time semiclassical behavior correctly describe the
eigenstate structure.Comment: 4 pages, including 2 figure
Semiclassical Construction of Random Wave Functions for Confined Systems
We develop a statistical description of chaotic wavefunctions in closed
systems obeying arbitrary boundary conditions by combining a semiclassical
expression for the spatial two-point correlation function with a treatment of
eigenfunctions as Gaussian random fields. Thereby we generalize Berry's
isotropic random wave model by incorporating confinement effects through
classical paths reflected at the boundaries. Our approach allows to explicitly
calculate highly non-trivial statistics, such as intensity distributions, in
terms of usually few short orbits, depending on the energy window considered.
We compare with numerical quantum results for the Africa billiard and derive
non-isotropic random wave models for other prominent confinement geometries.Comment: To be submitted to Physical Review Letter
Localization of Eigenfunctions in the Stadium Billiard
We present a systematic survey of scarring and symmetry effects in the
stadium billiard. The localization of individual eigenfunctions in Husimi phase
space is studied first, and it is demonstrated that on average there is more
localization than can be accounted for on the basis of random-matrix theory,
even after removal of bouncing-ball states and visible scars. A major point of
the paper is that symmetry considerations, including parity and time-reversal
symmetries, enter to influence the total amount of localization. The properties
of the local density of states spectrum are also investigated, as a function of
phase space location. Aside from the bouncing-ball region of phase space,
excess localization of the spectrum is found on short periodic orbits and along
certain symmetry-related lines; the origin of all these sources of localization
is discussed quantitatively and comparison is made with analytical predictions.
Scarring is observed to be present in all the energy ranges considered. In
light of these results the excess localization in individual eigenstates is
interpreted as being primarily due to symmetry effects; another source of
excess localization, scarring by multiple unstable periodic orbits, is smaller
by a factor of .Comment: 31 pages, including 10 figure
Scarring Effects on Tunneling in Chaotic Double-Well Potentials
The connection between scarring and tunneling in chaotic double-well
potentials is studied in detail through the distribution of level splittings.
The mean level splitting is found to have oscillations as a function of energy,
as expected if scarring plays a role in determining the size of the splittings,
and the spacing between peaks is observed to be periodic of period
{} in action. Moreover, the size of the oscillations is directly
correlated with the strength of scarring. These results are interpreted within
the theoretical framework of Creagh and Whelan. The semiclassical limit and
finite-{} effects are discussed, and connections are made with reaction
rates and resonance widths in metastable wells.Comment: 22 pages, including 11 figure
A realistic example of chaotic tunneling: The hydrogen atom in parallel static electric and magnetic fields
Statistics of tunneling rates in the presence of chaotic classical dynamics
is discussed on a realistic example: a hydrogen atom placed in parallel uniform
static electric and magnetic fields, where tunneling is followed by ionization
along the fields direction. Depending on the magnetic quantum number, one may
observe either a standard Porter-Thomas distribution of tunneling rates or, for
strong scarring by a periodic orbit parallel to the external fields, strong
deviations from it. For the latter case, a simple model based on random matrix
theory gives the correct distribution.Comment: Submitted to Phys. Rev.
Using self-definition to predict the influence of procedural justice on organizational, interpersonal, and job/task-oriented citizenship behaviors
An integrative self-definition model is proposed to improve our understanding of how procedural justice affects different outcome modalities in organizational behavior. Specifically, it is examined whether the strength of different levels of self-definition (collective, relational, and individual) each uniquely interact with procedural justice to predict organizational, interpersonal, and job/task-oriented citizenship behaviors, respectively. Results from experimental and (both single and multisource) field data consistently revealed stronger procedural justice effects (1) on organizational-oriented citizenship behavior among those who define themselves strongly in terms of organizational characteristics, (2) on interpersonal-oriented citizenship behavior among those who define themselves strongly in terms of their interpersonal relationships, and (3) on job/task-oriented citizenship behavior among those who define themselves weakly in terms of their distinctiveness or uniqueness. We discuss the relevance of these results with respect to how employees can be motivated most effectively in organizational settings
Biomarkers for Diagnosis and Prognosis of Sinusoidal Obstruction Syndrome after Hematopoietic Cell Transplantation.
Reliable, non-invasive methods for diagnosing and prognosing sinusoidal obstruction syndrome (SOS) early after hematopoietic cell transplantation (HCT) are needed. We used a quantitative mass spectrometry-based proteomics approach to identify candidate biomarkers of SOS by comparing plasma pooled from 20 patients with and 20 patients without SOS. Of 494 proteins quantified, we selected six proteins [L-Ficolin, vascular-cell-adhesion-molecule-1 (VCAM1), tissue-inhibitor of metalloproteinase-1, von Willebrand factor, intercellular-adhesion-molecule-1, and CD97] based on a differential heavy/light isotope ratio of at least 2 fold, information from the literature, and immunoassay availability. Next, we evaluated the diagnostic potential of these six proteins and five selected from the literature [suppression of tumorigenicity-2 (ST2), angiopoietin-2 (ANG2), hyaluronic acid (HA), thrombomodulin, and plasminogen activator inhibitor-1] in samples from 80 patients. The results demonstrate that together ST2, ANG2
Strategies Outside the Formal Classroom: Nonprofit Management Education in Transparency and Accountability
A demand for nonprofit management training and organizational capacity building exists in Latin America. However, few nonprofit management education (NME) programs in Latin America exist, and there is limited content related to ethics, transparency, and accountability. Using the case of Ecuador, we identify three strategies implemented by nonprofit leaders to cope with limited NME. We find that first, organizations engage in a process of collectivity that seeks to explore and give meaning to civil society in Ecuador. Second, this process leads to the production of knowledge about civil society in Ecuador. And third, based on both the process of collectivity and knowledge production, nonprofit leaders in Ecuador take ownership in the training of nonprofit leaders through several pilot courses related to transparency and accountability. The case of Ecuador reminds public affairs educators that organizations themselves can be successful producers of knowledge that can and should create and inform curricular content
Justice and feelings: Toward a new era in justice research
In this special issue, the relationship between feelings and justice and its consequences are highlighted. Five articles discuss the role that affect, feelings, and emotions play in justice processes across a variety of social settings. In the present introductory article, the position of past and present justice research in relationship to these topics is briefly reviewed. In addition, reasons are outlined to show why a focus on these issues may be pivotal for a better understanding of social justice and how this may pave the way for a new, more process-oriented era in social justice research, focusing more on “hot” cognitive aspects as they pertain to social justice concerns
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