Negative Effective Mass Density of Acoustic Metamaterial using Dual-Resonator Spring-Mass Model

In this paper, we propose an acoustic metamaterial with a microstructure consisting of two internal resonators. The performance of this dual-resonator metamaterial is compared to the original singleresonator metamaterial. Analytical findings show that the dual-resonator metamaterial exhibits its negative effective mass density over a larger frequency spectrum, particularly at two distinctively asymptotic regions. The wave propagation phenomenon in the metamaterial is investigated using finite element simulation. Computational results reveal that the dual-resonator metamaterial is capable of attenuating wave propagation in a larger operating frequency. Practical applications like vibration control and blast mitigation are demonstrated and discussed

Effective Prevention of Adolescent Substance Abuse – Educational versus Deterrent Approaches

Substance abuse, especially among adolescents, has long been an important issue in society. In light of the adverse impact of substance abuse, scholars, educators, and policy-makers have proposed different approaches to prevent and reduce such abuse. This paper investigates the effectiveness of the two prominent approaches—educational and deterrent—in preventing and reducing adolescent substance abuse. The educational approach (e.g., school-based prevention programming) tends to be more comprehensive and better grounded in theories than the deterrent approach (e.g., drug testing). The educational approach not only targets multiple psychosocial factors contributing to substance abuse, but it is also supported by empirical studies showing that school-based prevention programming is effective in preventing substance abuse and has long-lasting positive influences on adolescent development. Practical implications of implementing school-based prevention programming are also discussed. L'abus d'alcool ou d'autres drogues, surtout chez les adolescents, constitue depuis longtemps une préoccupation importante de la société. À la lumière de l'impact défavorable de cet abus, les chercheurs, enseignants et décideurs ont proposé différentes approches pour le prévenir et le limiter. Cet article porte sur l'efficacité de deux approches importantes, l'une pédagogique, l'autre dissuasive, visant la prévention et la réduction de l'abus d'alcool ou d'autres drogues chez les adolescents. L'approche pédagogique (par ex. les programmes de prévention en milieu scolaire) est, de façon générale, plus globale et mieux fondée sur les théories que l'approche dissuasive (par ex. dépistage des drogues). Non seulement l'approche pédagogique cible-t-elle les divers facteurs psychosociaux qui contribuent à cet abus, elle est de plus appuyée par des études empiriques indiquant que les programmes de prévention en milieu scolaire sont des outils efficaces dans la prévention de l'abus d'alcool ou d'autres drogues et qu'ils ont un impact positif à long terme sur le développement des adolescents. Nous discutons des répercussions pratiques de la mise en œuvre des programmes de prévention en milieu scolaire

Room Temperature Light-Mediated Long-Range Coupling of Excitons in Perovskites

Perovskites have been the focus of attention due to their multitude of outstanding optoelectronic properties and structural versatility. Two-dimensional halide perovskite such as (C_6H_5C_2H_4NH_3)_2PbI_4, or simply PEPI, forms natural multiple quantum wells with enhanced light-matter interactions, making them attractive systems for further investigation. This work reports tunable splitting of exciton modes in PEPI resulting from strong light-matter interactions, manifested as multiple dips (modes) in the reflection spectra. While the origin of the redder mode is well understood, that for the bluer dip at room temperature is still lacking. Here, it is revealed that the presence of the multiple modes originates from an indirect coupling between excitons in different quantum wells. The long-range characteristic of the mediated coupling between excitons in distant quantum wells is also demonstrated in a structure design along with its tunability. Moreover, a device architecture involving an end silver layer enhances the two excitonic modes and provides further tunability. Importantly, this work will motivate the possibility of coupling of the excitonic modes with a confined light mode in a microcavity to produce multiple exciton-polariton modes.Comment: 12 pages, 11 figure

The Split-Algebras and Non-compact Hopf Maps

We develop a noncompact version of the Hopf maps based on the split algebras. The split algebras consist of three species: split-complex numbers, split quaternions, and split octonions. They correspond to three noncompact Hopf maps that represent topological maps between hyperboloids in different dimensions with hyperboloid bundle. We realize such noncompact Hopf maps in two ways: one is to utilize the split-imaginary unit, and the other is to utilize the ordinary imaginary unit. Topological structures of the hyperboloid bundles are explored, and the canonical connections are naturally regarded as noncompact gauge field of monopoles.Comment: 40 pages, no figures, + 8 pages, discussions and references added, published versio

Smooth Paths on Three Dimensional Lattice

A particular class of random walks with a spin factor on a three dimensional cubic lattice is studied. This three dimensional random walk model is a simple generalization of random walk for the two dimensional Ising model. All critical diffusion constants and associated critical exponents are calculated. Continuum field theories such as Klein-Gordon, Dirac and massive Chern-Simons theories are constructed near several critical points.Comment: 7 pages,NUP-A-94-

Detailed balance has a counterpart in non-equilibrium steady states

When modelling driven steady states of matter, it is common practice either to choose transition rates arbitrarily, or to assume that the principle of detailed balance remains valid away from equilibrium. Neither of those practices is theoretically well founded. Hypothesising ergodicity constrains the transition rates in driven steady states to respect relations analogous to, but different from the equilibrium principle of detailed balance. The constraints arise from demanding that the design of any model system contains no information extraneous to the microscopic laws of motion and the macroscopic observables. This prevents over-description of the non-equilibrium reservoir, and implies that not all stochastic equations of motion are equally valid. The resulting recipe for transition rates has many features in common with equilibrium statistical mechanics.Comment: Replaced with minor revisions to introduction and conclusions. Accepted for publication in Journal of Physics

Perturbing Topological Field Theories

The abelian Chern-Simons theory is perturbed by introducing local gauge-invariant interaction terms depending on the curvature. The computation of the correlation function of two Wilson lines for two smooth closed nonintersecting curves is reported up to four loops and is shown to be unaffected by radiative corrections. This result ensures the stability of the linking number of the two curves with respect to the local perturbations which may be added to the Chern-Simons action.Comment: 13 pages, 5 figures, corrected some typo

Comparative study of line voltage stability indices for voltage collapse forecasting in power transmission system

At present, the evaluation of voltage stability assessment experiences sizeable anxiety in the safe operation of power systems. This is due to the complications of a strain power system. With the snowballing of power demand by the consumers and also the restricted amount of power sources, therefore, the system has to perform at its maximum proficiency. Consequently, the noteworthy to discover the maximum ability boundary prior to voltage collapse should be undertaken. A preliminary warning can be perceived to evade the interruption of power system’s capacity. The effectiveness of line voltage stability indices (LVSI) is differentiated in this paper. The main purpose of the indices used is to predict the proximity of voltage instability of the electric power system. On the other hand, the indices are also able to decide the weakest load buses which are close to voltage collapse in the power system. The line stability indices are assessed using the IEEE 14 bus test system to validate its practicability. Results demonstrated that the implemented indices are practically relevant in predicting the manifestation of voltage collapse in the system. Therefore, essential actions can be taken to dodge the incident from arising

Tracking disease resistance deployment in potato breeding by enrichment sequencing

Following the molecular characterisation of functional disease resistance genes in recent years, methods to track and verify the integrity of multiple genes in varieties are needed for crop improvement through resistance stacking. Diagnostic resistance gene enrichment sequencing (dRenSeq) enables the highconfidence identification and complete sequence validation of known functional resistance genes in crops. As demonstrated for tetraploid potato varieties, the methodology is more robust and cost-effective in monitoring resistances than whole-genome sequencing and can be used to appraise (trans)gene integrity efficiently. All currently known NB-LRRs effective against viruses, nematodes and the late blight pathogen Phytophthora infestans can be tracked with dRenSeq in potato and hitherto unknown polymorphisms have been identified. The methodology provides a means to improve the speed and efficiency of future disease resistance breeding in crops by directing parental and progeny selection towards effective combinations of resistance genes

Thermodynamics of an Anyon System

We examine the thermal behavior of a relativistic anyon system, dynamically realized by coupling a charged massive spin-1 field to a Chern-Simons gauge field. We calculate the free energy (to the next leading order), from which all thermodynamic quantities can be determined. As examples, the dependence of particle density on the anyon statistics and the anyon anti-anyon interference in the ideal gas are exhibited. We also calculate two and three-point correlation functions, and uncover certain physical features of the system in thermal equilibrium.Comment: 18 pages; in latex; to be published in Phys. Rev.