Relaxation of isolated quantum systems beyond chaos

In classical statistical mechanics there is a clear correlation between relaxation to equilibrium and chaos. In contrast, for isolated quantum systems this relation is -- to say the least -- fuzzy. In this work we try to unveil the intricate relation between the relaxation process and the transition from integrability to chaos. We study the approach to equilibrium in two different many body quantum systems that can be parametrically tuned from regular to chaotic. We show that a universal relation between relaxation and delocalization of the initial state in the perturbed basis can be established regardless of the chaotic nature of system.Comment: 4+ pages, 4 figs. Closest to published versio

Multifractality of quantum wave packets

We study a version of the mathematical Ruijsenaars-Schneider model, and reinterpret it physically in order to describe the spreading with time of quantum wave packets in a system where multifractality can be tuned by varying a parameter. We compare different methods to measure the multifractality of wave packets, and identify the best one. We find the multifractality to decrease with time until it reaches an asymptotic limit, different from the mulifractality of eigenvectors, but related to it, as is the rate of the decrease. Our results could guide the study of experimental situations where multifractality is present in quantum systems.Comment: 6 pages, 4 figures, final version including a new figure (figure 1

Lyapunov decay in quantum irreversibility

The Loschmidt echo -- also known as fidelity -- is a very useful tool to study irreversibility in quantum mechanics due to perturbations or imperfections. Many different regimes, as a function of time and strength of the perturbation, have been identified. For chaotic systems, there is a range of perturbation strengths where the decay of the Loschmidt echo is perturbation independent, and given by the classical Lyapunov exponent. But observation of the Lyapunov decay depends strongly on the type of initial state upon which an average is done. This dependence can be removed by averaging the fidelity over the Haar measure, and the Lyapunov regime is recovered, as it was shown for quantum maps. In this work we introduce an analogous quantity for systems with infinite dimensional Hilbert space, in particular the quantum stadium billiard, and we show clearly the universality of the Lyapunov regime.Comment: 8 pages, 6 figures. Accepted in Phil. Trans. R. Soc.

Translation Factors Specify Cellular Metabolic State

In this issue of $\small \textit{Cell Reports}$, Shah et al. present evidence that a subcomplex of the eIF3 translation initiation factor regulates translation of mRNAs encoding components of the mitochondrial electron transport chain and glycolytic enzymes, thus linking translational control with energy metabolism

Mobile Paving System (MPS): A New Large Scale Freeform Fabrication Method

In the last decade, significant opportunities for automation have been identified in the area of construction. Soaring labor and material costs have driven multiple research efforts in construction automation. In this paper, we present a novel means for construction automation that involves the fusion of the rapid prototyping, controls and mechatronics technologies. The resultant autonomous construction mechanism has been designed for commercial applications. Mobile Paving System (MPS) is a new freeform fabrication process which is capable of rapidly producing variable profiles such as curbs and sidewalks out of materials like cement and asphalt. Path generation and guidance of the construction operation is controlled by a mobile robot. This article presents an overview of research and development efforts that are aimed at establishing the feasibility and the potential of the process.Mechanical Engineerin

Weyl law for fat fractals

It has been conjectured that for a class of piecewise linear maps the closure of the set of images of the discontinuity has the structure of a fat fractal, that is, a fractal with positive measure. An example of such maps is the sawtooth map in the elliptic regime. In this work we analyze this problem quantum mechanically in the semiclassical regime. We find that the fraction of states localized on the unstable set satisfies a modified fractal Weyl law, where the exponent is given by the exterior dimension of the fat fractal.Comment: 8 pages, 4 figures, IOP forma

In Pursuit of the Ed.D.: A Study of East Tennessee State University\u27s Doctors of Education: Who They are and Why They Persisted.

According to Kerlin (1995a), first-generation students are not expected to survive to doctorate degree attainment because of vulnerability to negative affects associated with their status; yet persist they do at East Tennessee State University. The desire to study the first-generation East Tennessee State University\u27s Doctors of Education and the limited number of first-generation graduate studies available, especially in the academic field of education, promoted developing this study. It was the intent of this study to offer additional empirical research toward understanding variables associated with first-generation persistence as encountered by East Tennessee State University\u27s Doctors of education. Quantitative analysis derived through survey research served as an explanatory framework to investigate major variables of first-generation persistence. The survey targeted East Tennessee State University\u27s Doctors of Education who received degrees prior to June 2004. Investigation of empirical evidence revealed that unlike previous first-generation studies (Hayes, 1997; Hurley, 2002; Inman and Mayes, 1999; Khanh, 2002; NCES, 1998; Terenzini, Springer, Yaeger, Pascarella, and Nora, 1996) the bulk (73.7%) of East Tennessee State University Doctors of Education were first-generation. Moreover, although previous studies suggested the presence of unique barriers attributed to first-generation status, no significant differences resulted in either identification or ranking of barriers or facilitators to degree attainment between first-generation East Tennessee State University\u27s Doctors of Education and their non-first-generation counterparts. The Survey of ETSU Doctors of Education requested respondents prioritize identified barriers and facilitators. After plotting significant bivariate coordinate pairs among ranked barriers and facilitators, flat line (zero sloped) clusters depicted the presence of six weak monotone associations among variables. Facilitator rankings were associated with a respondent\u27s age, parental college attendance, and education specialist degree, while barrier rankings were associated with a respondent\u27s marital status at the time of degree attainment, secondary support source, and post doctorate employment