Hyperbolic metamaterial interfaces: Hawking radiation from Rindler horizons and the "end of time"

Extraordinary rays in a hyperbolic metamaterial behave as particle world lines in a three dimensional (2+1) Minkowski spacetime. We analyze electromagnetic field behavior at the boundaries of this effective spacetime depending on the boundary orientation. If the boundary is perpendicular to the space-like direction in the metamaterial, an effective Rindler horizon may be observed which produces Hawking radiation. On the other hand, if the boundary is perpendicular to the time-like direction an unusual physics situation is created, which can be called "the end of time". It appears that in the lossless approximation electromagnetic field diverges at the interface in both situations. Experimental observations of the "end of time" using plasmonic metamaterials confirm this conclusion.Comment: 21 pages, 4 figure

Factor market oligopsony and the location decision of free entry oligopoly

This paper examines the impact of oligopsony power on the location decision of undifferentiated oligopolistic firms with free entry. In the case where the distance of an oligopolistic firm from the output market is held constant, it shows that the optimum location moves away from the oligopsonistic input market if the demand function and the labor supply function are linear. In the case where the distance of an oligopolistic firm from the output market is a decision variable, it shows that the optimum location may not move toward the output market as demand increases if the demand function is convex. These results are significantly different from the conventional results based on the perfectly competitive factor market. It indicates that the presence of oligopsony power has important influence on the location decision of oligopolistic firms.Free entry oligopoly

A general BRST approach to string theories with zeta function regularizations

We propose a new general BRST approach to string and string-like theories which have a wider range of applicability than e g the conventional conformal field theory method. The method involves a simple general regularization of all basic commutators which makes all divergent sums to be expressible in terms of zeta functions from which finite values then may be extracted in a rigorous manner. The method is particular useful in order to investigate possible state space representations to a given model. The method is applied to three string models: The ordinary bosonic string, the tensionless string and the conformal tensionless string. We also investigate different state spaces for these models. The tensionless string models are treated in details. Although we mostly rederive known results they appear in a new fashion which deepens our understanding of these models. Furthermore, we believe that our treatment is more rigorous than most of the previous ones. In the case of the conformal tensionless string we find a new solution for d=4.Comment: 21 pages,Latexfile,revised presentation, previous title:"Critical dimensions and zeta regularizations in string theories

Universality of Sea Wave Growth and Its Physical Roots

Modern day studies of wind-driven sea waves are usually focused on wind forcing rather than on the effect of resonant nonlinear wave interactions. The authors assume that these effects are dominating and propose a simple relationship between instant wave steepness and time or fetch of wave development expressed in wave periods or lengths. This law does not contain wind speed explicitly and relies upon this asymptotic theory. The validity of this law is illustrated by results of numerical simulations, in situ measurements of growing wind seas and wind wave tank experiments. The impact of the new vision of sea wave physics is discussed in the context of conventional approaches to wave modeling and forecasting.Comment: submitted to Journal of Fluid Mechanics 24-Sep-2014, 34 pages, 10 figure

Diquaternary Ammonium Compounds in Zeolite Synthesis: Cyclic and Polycyclic N-Heterocycles Connected by Methylene Chains

An additional dimension has been added to our long-standing studies in high silica zeolite synthesis via a guest/host synergism. We have created and studied the impact of making symmetric diquaternary ammonium compounds, by varying the chain length between nitrogen charge centers, and the heterocycle size and geometry containing the nitrogen. This allows the introduction of a second spatial parameter in the use of the charged organo-cation guest in the zeolite synthesis. The series of 15 diquaternary ammonium compounds (5 heterocycles synthesized onto chain lengths of C4−C6) were tested in a total of 135 zeolite syntheses reactions. Nine screening reactions were employed for each guest molecule, and the conditions built upon past successes in finding novel high silica zeolites via introduction of boron, aluminum, or germanium as substituting tetrahedral framework atoms for silicon. Eighteen different zeolite structures emerged from the studies. The use of specific chain lengths for derivatives of the pyrrolidine ring system produced novel zeolite materials SSZ-74 and 75

Relativistic Hydrodynamic Cosmological Perturbations

Relativistic cosmological perturbation analyses can be made based on several different fundamental gauge conditions. In the pressureless limit the variables in certain gauge conditions show the correct Newtonian behaviors. Considering the general curvature ($K$) and the cosmological constant ($\Lambda$) in the background medium, the perturbed density in the comoving gauge, and the perturbed velocity and the perturbed potential in the zero-shear gauge show the same behavior as the Newtonian ones in general scales. In the first part, we elaborate these Newtonian correspondences. In the second part, using the identified gauge-invariant variables with correct Newtonian correspondences, we present the relativistic results with general pressures in the background and perturbation. We present the general super-sound-horizon scale solutions of the above mentioned variables valid for general $K$, $\Lambda$, and generally evolving equation of state. We show that, for vanishing $K$, the super-sound-horizon scale evolution is characterised by a conserved variable which is the perturbed three-space curvature in the comoving gauge. We also present equations for the multi-component hydrodynamic situation and for the rotation and gravitational wave.Comment: 16 pages, no figure, To appear in Gen. Rel. Gra

A strategic study of energy efficient and hybrid energy system options for a multi-family building in Korea

This study is to identify performance of energy efficiency measures and to match low-carbon and renewable energy (RE) systems supplies to demands in the context of multi-family residential buildings in Korea. An approach to the evaluation of the hybrid energy systems was investigated, including consideration of heat and power demand profiles, energy system combinations, building design options and strategies for matching supply to demand. The approach is encapsulated within an integrated software environment. Building energy simulation technology was exploited to make virtual energy use data. Low-carbon and RE system modelling techniques were used to predict energy supply profiles. A series of demand/supply matching-based analyses were made to identify the effect of energy efficient demand measures (e.g. roof-top gardens, innovative underfloor heating system) and evaluate the capacity utilisation factor from the hybrid energy systems. On the basis of performance information obtained at the conceptual design stage, the design team can pinpoint the most energy efficient demand/supply combination, and consequently, maximise the impact of hybrid energy systems adoption

Relationship between Teamwork and Team Performance: Experiences from an ERPsim Competition

Much interest exists in using Enterprise Resource Planning simulation (ERPsim) games to help students learn complex concepts involved in Enterprise Resource Planning (ERP) systems. However, little research has explored factors that contribute to team performance duringan ERPsim game. The current study investigated teamwork as a contributor to team performance in the context of a competition. The research measured teamwork in five dimensions: contributing to the team’s work, interacting with teammates, keeping the teamon track, expecting quality, and having relevant knowledge, skills, and abilities (KSA). Net income was the measure for team performance. Participants also rated their satisfaction with their team. Data from 62 student teams showedthat all five teamwork dimensions had a positive correlation with net income. Moreover, all correlations were statistically significant except the relationship between keeping the team on track and net income. Teams with relevant KSA were more likely to generate higher net income. Expecting quality was the second most significant dimension, followed by interacting with teammates and contributing to the team’s work. All five teamwork dimensions had a significant positive correlation with team satisfaction.This research suggests that students will likely engage in good teamwork during a game if it is set up as a high-stakes competition. Additionally, good teamwork will likely result in higher team performance and satisfaction. The evidence should encourage more widespread adoption of ERPsim gamesas a means for teaching and assessing teamwork in addition to learning ERP concepts