Terahertz Logic Gate Operations in a Toroidal Metasurface

The applications of terahertz metamaterials are being actively explored in recent times for applications in high-speed communication devices, miniature photonic circuits, and bio-chemical devices because of their wide advantages. The toroidal resonance, a new type of metasurface resonance, has been examined with great interest to utilize its properties in terahertz metasurface applications. The study reports a proof of concept design of a toroidal metasurface that experimentally demonstrates logic gate operations in the terahertz frequency regime by passive tuning of the split ring resonators compromising the meta-atom design. The amplitude modulation is utilized as a method of determining the Boolean logic output of the system. The proposed metasurface could be further optimized for high amplitude modulations, as well as for active logic gate operations using tunable materials including graphene and ITO. The proposed metasurface consists of three split-ring resonators, and the near-field coupling between the adjacent resonators dictates the logic gate operations. The toroidal excitation in the metasurface is determined by a multipole analysis of the scattered powers of terahertz radiation. The proposed metasurfaces experimentally define AND Boolean logic gate at 0.89 terahertz, and OR Boolean logic gate at 0.97 terahertz. Numerical simulations support the experimentally obtained results. Additionally, we numerically report the excitation of NAND gate at 0.87 THz. Such toroidal logic-gate metasurfaces in the terahertz region could find applications in digitized terahertz circuits for photonic device applications

Road Rage Menace: A Cross-sectional Study to Assess Driver Anger Level in Public Motor Vehicle Drivers in a City in Central India

Introduction: Road rage and aggressive driving is a prevalent condition in today’s society due to motorists’ frustrations during heavy traffic volumes. Objective: This study was done to assess the level of anger amongst the drivers of public transport vehicles in Indore, using Driving Anger Scale (DAS by Deffenbacher et. al.) and various factors affecting it. Material and Methods: A cross-sectional study was conducted among 135 drivers of Public transport vehicle drivers (Star bus, City-van and star cab drivers) in Indore to assess their anger level using Driving Anger Scale. The participants were required to record the amount of anger they would experience in response to each item in the scale (1=not at all angry, 2=a little angry, 3=some anger, 4=much anger, 5=very much angry). Results: The mean DAS score in Indore was found to be 3.013 and in the three organizations namely Star bus drivers, City van drivers and Star cab drivers was 2.92, 3.08 and 3.04 respectively. The DAS score of drivers with respect to the 6 sub-scales were: hostile gestures (Star bus -3.42,City van -3.67,Star cab -3.38), slow driving (Star bus -2.73,City van driv-2.78,Star cab-3.17), traffic obstructions (Star bus-2.85,City van -3.25,Star cab-3.18), discourtesy (Star bus -3.23,City van-3.33,Star cab -3.25)and police presence (Star bus -2.15,City van -1.99,Star cab -2.78), illegal driving (Star bus -3.04,City van -3.14,Star cab -2.89). The DAS scores of the drivers did not vary significantly with age group, experience, and educational qualification. Conclusion: Though DAS scores did not vary between the three groups of drivers, however average level anger for various given circumstances commonly found in the Indian traffic scenario was on the higher side

Polarization independent lattice-coupled terahertz toroidal excitations

The toroidal dipole excitation is an important field for metamaterial research because of their low-loss attribute. In this study, we demonstrate numerically and experimentally, a unique polarization independent terahertz metamaterial that modulates a broad resonance into a sharp mode by coupling the inherent toroidal dipole excitation to the lattice mode of the metasurface. The advantage of polarization independence in the metasurface enables the excitation of lattice-coupled toroidal mode for both the transverse electric and transverse magnetic modes of the incident terahertz radiation. The interaction of the two dark low-loss modes results in the significant enhancement of the quality factor of the metasurface at the point of resonance matching. Such a polarization independent lattice-matched toroidal excitation-based device has the potential to impact the development of low loss terahertz component for ultrasensitive sensors, low loss equipment, and slow light devices for enhanced light matter interaction.Comment: 6 figures, 4 page