Fronts Propagation at the Onset of Plastic Yielding

The existence of a finite threshold, the yield stress, for the onset of plastic yielding is a universal feature of plasticity. This jamming-unjamming transition is naturally accounted for by the dynamics of a bistable internal state field. We show, within the athermal Shear Transformation Zones (STZ) theory of amorphous plasticity, that the transition is accompanied by the propagation of plastic fronts. We further show that the mean-field theory cannot select the velocity of these fronts and go beyond the mean-field description to include fluctuations and correlations effects, resulting in new nonlocal terms in the equations. Finally, we demonstrate that the new terms, with an associated intrinsic lengthscale, provide a velocity selection mechanism for the plastic fronts.Comment: 6 pages, 1 figure; reorganized paper, friction part omitte

Modeling an Electrically Driven Graphene-Nanoribbon Laser for Optical Interconnects

Graphene has two very important optical properties of population inversion of electrons, and broadband optical gain. As a result, graphene has potential for use in lasers and amplifiers. In this work, we presented a quantum master model and analyzed the properties for the electrically pumped single-AGNR vertical-cavity surface-emitting lasers (VCSELs) to investigate the lasing action and laser properties for realistic experimental parameters. A semiclassical approximation for the output power and laser linewidth is also derived. The laser threshold power was several orders of magnitude lower than that currently achievable with semiconductor microlasers. Our results have demonstrated that a single-AGNR VCSEL can serve as a nanolaser with ultralow lasing threshold. Implementation of such a GNR-based VCSEL is especially promising for optical interconnection systems since VCSELs emit low optical power and single longitudinal mode over a wide wavelength spectral range through tailoring GNRs.Comment: 5 pages, 4 figures, http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=6458072&tag=

The Influence of Parental Control and Parent-Child Relational Qualities on Adolescent Internet Addiction: A 3-Year Longitudinal Study in Hong Kong

This study investigated how parental behavioral control, parental psychological control, and parent-child relational qualities predicted the initial level and rate of change in adolescent internet addiction (IA) across the junior high school years. The study also investigated the concurrent and longitudinal effects of different parenting factors on adolescent IA. Starting from the 2009/2010 academic year, 3,328 Grade 7 students (Mage = 12.59 ± 0.74 years) from 28 randomly selected secondary schools in Hong Kong responded on a yearly basis to a questionnaire measuring multiple constructs including socio-demographic characteristics, perceived parenting characteristics, and IA. Individual growth curve (IGC) analyses showed that adolescent IA slightly decreased during junior high school years. While behavioral control of both parents was negatively related to the initial level of adolescent IA, only paternal behavioral control showed a significant positive relationship with the rate of linear change in IA, suggesting that higher paternal behavioral control predicted a slower decrease in IA. In addition, fathers\u27 and mothers\u27 psychological control was positively associated with the initial level of adolescent IA, but increase in maternal psychological control predicted a faster drop in IA. Finally, parent-child relational qualities negatively and positively predicted the initial level and the rate of change in IA, respectively. When all parenting factors were considered simultaneously, multiple regression analyses revealed that paternal behavioral control and psychological control as well as maternal psychological control and mother-child relational quality were significant concurrent predictors of adolescent IA at Wave 2 and Wave 3. Regarding the longitudinal predicting effects, paternal psychological control and mother-child relational quality at Wave 1 were the two most robust predictors of later adolescent IA at Wave 2 and Wave 3. The above findings underscore the importance of the parent-child subsystem qualities in influencing adolescent IA in the junior high school years. In particular, these findings shed light on the different impacts of fathering and mothering which are neglected in the scientific literature. While the findings based on the levels of IA are consistent with the existing theoretical models, findings on the rate of change are novel

The US/Canada Difference in Postsecondary Educational Choice

This paper attempts to tackle the puzzle of why more Canadians choose community colleges over universities than their American counterparts, when previous research has suggested that the return to community college education is low in Canada. Using data from the Survey of Labour and Income Dynamics for Canada and the National Longitudinal Survey of Youth 79 for the US, I estimate returns to education with a trinomial selection correction using various instruments. I simulate the educational choices of Canadians who face American returns to education, and vice versa. I found that Canadians have a relatively strong incentive to choose community colleges if occupational choices are controlled for. The second finding is that Canadian universities and colleges specialize in different types of human capital. Also, my analysis confirms that the elasticity of educational attainment to tuition and fees is low. Finally, the self-selection processes in the two countries are different. More able Americans have higher educational attainment while more productive Canadians prefer going to universities but not community colleges.Returns to Education; Educational Choices; Post-secondary Education.

VLSI architecture for a Reed-Solomon decoder

A basic single-chip building block for a Reed-Solomon (RS) decoder system is partitioned into a plurality of sections, the first of which consists of a plurality of syndrome subcells each of which contains identical standard-basis finite-field multipliers that are programmable between 10 and 8 bit operation. A desired number of basic building blocks may be assembled to provide a RS decoder of any syndrome subcell size that is programmable between 10 and 8 bit operation