Long-range Energy Transfer and Ionization in Extended Quantum Systems Driven by Ultrashort Spatially Shaped Laser Pulses

The processes of ionization and energy transfer in a quantum system composed of two distant H atoms with an initial internuclear separation of 100 atomic units (5.29 nm) have been studied by the numerical solution of the time-dependent Schr\"odinger equation beyond the Born-Oppenheimer approximation. Thereby it has been assumed that only one of the two H atoms was excited by temporally and spatially shaped laser pulses at various laser carrier frequencies. The quantum dynamics of the extended H-H system, which was taken to be initially either in an unentangled or an entangled ground state, has been explored within a linear three-dimensional model, including two z coordinates of the electrons and the internuclear distance R. An efficient energy transfer from the laser-excited H atom (atom A) to the other H atom (atom B) and the ionization of the latter have been found. It has been shown that the physical mechanisms of the energy transfer as well as of the ionization of atom B are the Coulomb attraction of the laser driven electron of atom A by the proton of atom B and a short-range Coulomb repulsion of the two electrons when their wave functions strongly overlap in the domain of atom B.Comment: 11 pages, 7 figure

A new regime of anomalous penetration of relativistically strong laser radiation into an overdense plasma

It is shown that penetration of relativistically intense laser light into an overdense plasma, accessible by self-induced transparency, occurs over a finite length only. The penetration length depends crucially on the overdense plasma parameter and increases with increasing incident intensity after exceeding the threshold for self-induced transparency. Exact analytical solutions describing the plasma-field distributions are presented.Comment: 6 pages, 2 figures in 2 separate eps files; submitted to JETP Letter

Multi-filament structures in relativistic self-focusing

A simple model is derived to prove the multi-filament structure of relativistic self-focusing with ultra-intense lasers. Exact analytical solutions describing the transverse structure of waveguide channels with electron cavitation, for which both the relativistic and ponderomotive nonlinearities are taken into account, are presented.Comment: 21 pages, 12 figures, submitted to Physical Review

Bilateral symmetry breaking in a nonlinear Fabry-Perot cavity exhibiting optical tristability

We show the existence of a region in the parameter space that defines the field dynamics in a Fabry-Perot cylindrical cavity, where three output stable stationary states of the light are possible for a given localized incident field. Two of these states do not preserve the bilateral (i.e. left-right) symmetry of the entire system. These broken-symmetry states are the high-transmission nonlinear modes of the system. We also discuss how to excite these states.Comment: 5 pages, 5 figure

Stability of narrow beams in bulk Kerr-type nonlinear media

We consider (2+1)-dimensional beams, whose transverse size may be comparable to or smaller than the carrier wavelength, on the basis of an extended version of the nonlinear Schr\"{o}dinger equation derived from the Maxwell`s equations. As this equation is very cumbersome, we also study, in parallel to it, its simplified version which keeps the most essential term: the term which accounts for the {\it nonlinear diffraction}. The full equation additionally includes terms generated by a deviation from the paraxial approximation and by a longitudinal electric-field component in the beam. Solitary-wave stationary solutions to both the full and simplified equations are found, treating the terms which modify the nonlinear Schr\"{o}dinger equation as perturbations. Within the framework of the perturbative approach, a conserved power of the beam is obtained in an explicit form. It is found that the nonlinear diffraction affects stationary beams much stronger than nonparaxiality and longitudinal field. Stability of the beams is directly tested by simulating the simplified equation, with initial configurations taken as predicted by the perturbation theory. The numerically generated solitary beams are always stable and never start to collapse, although they display periodic internal vibrations, whose amplitude decreases with the increase of the beam power.Comment: 7 pages, 6 figures Accepted for publication in PR

A comparison of arbitration procedures for risk averse disputants

We propose an arbitration model framework that generalizes many previous quantitative models of final offer arbitration, conventional arbitration, and some proposed alternatives to them. Our model allows the two disputants to be risk averse and assumes that the issue(s) in dispute can be summarized by a single quantifiable value. We compare the performance of the different arbitration procedures by analyzing the gap between the disputants' equilibrium offers and the width of the contract zone that these offers imply. Our results suggest that final offer arbitration should give results superior to those of conventional arbitration.Natural Sciences & Engineering Research Council (NSERC) Discovery Gran

Electromagnetic energy penetration in the self-induced transparency regime of relativistic laser-plasma interactions

Two scenarios for the penetration of relativistically intense laser radiation into an overdense plasma, accessible by self-induced transparency, are presented. For supercritical densities less than 1.5 times the critical one, penetration of laser energy occurs by soliton-like structures moving into the plasma. At higher background densities laser light penetrates over a finite length only, that increases with the incident intensity. In this regime plasma-field structures represent alternating electron layers separated by about half a wavelength by depleted regions.Comment: 9 pages, 4 figures, submitted for publication to PR

Academic Performance and Behavioral Patterns

Identifying the factors that influence academic performance is an essential part of educational research. Previous studies have documented the importance of personality traits, class attendance, and social network structure. Because most of these analyses were based on a single behavioral aspect and/or small sample sizes, there is currently no quantification of the interplay of these factors. Here, we study the academic performance among a cohort of 538 undergraduate students forming a single, densely connected social network. Our work is based on data collected using smartphones, which the students used as their primary phones for two years. The availability of multi-channel data from a single population allows us to directly compare the explanatory power of individual and social characteristics. We find that the most informative indicators of performance are based on social ties and that network indicators result in better model performance than individual characteristics (including both personality and class attendance). We confirm earlier findings that class attendance is the most important predictor among individual characteristics. Finally, our results suggest the presence of strong homophily and/or peer effects among university students

Intensive Wheat Management for Yield and Quality: The Role of Variety, Environment, and Management Practices

Management (M), variety (V), and environment (E) greatly influence wheat yield and quality. With the objective of determining the partial influence of V, E, and M, we conducted a field experiment where we imposed four management intensities to five wheat varieties during six site-years in Kansas and Oklahoma. Management intensities were 1) low-input (N fertility for a yield goal of 60 bu/a); 2) high-input (foliar fungi­cide, sulfur and chloride fertilizers, growth regulator, and nitrogen (N) fertility for a yield goal of 100 bu/a); 3) high-input minus fungicide; and 4) high-input minus addi­tional N. We selected commonly grown wheat varieties with contrasting yield potential and quality characteristics. We used a split-plot design with M as whole-plots (estab­lished in randomized complete block design), and V as sub-plot (completely random­ized within whole-plot). Variance component analyses suggested that E accounted for 63% of the variability in wheat yield and 55% of the variability in grain test weight; G accounted for 1 and 23% of the variability in yield and test weight, and M accounted for 1% of the variability of both. The interactions V × G and E × M accounted for 4 and 9% of the variability in yield, and 10 and 1% of the variability in test weight, respectively. Analysis of variance pooled across the entire dataset considering V and M fixed and E random suggested a significant G × M interaction on yield, which ranged from 49–61 bu/a. Meanwhile, both V and M affected test weight, which ranged from 52–58 lb/bu for the different V and from 55–57 lb/bu for the different M. These results suggest that E has the greatest impact in yield and quality, but there is room for yield improvement through V-specific M, and for quality improvement through V and M separately