Engineering bound states in continuum via nonlinearity induced extra dimension

Bound states in continuum (BICs) are localized states of a system possessing significantly large life times with applications across various branches of science. In this work, we propose an expedient protocol to engineer BICs which involves the use of Kerr nonlinearities in the system. The generation of BICs is a direct artifact of the nonlinearity and the associated expansion in the dimensionality of the system. In particular, we consider single and two mode anharmonic systems and provide a number of solutions apposite for the creation of BICs. In close vicinity to the BIC, the steady state response of the system is immensely sensitive to perturbations in natural frequencies of the system and we illustrate its propitious sensing potential in the context of experimentally realizable setups for both optical and magnetic nonlinearities.Comment: 7 pages, 4 figure

Impact of Seasonal Changes on Water Characterstics at Palakkad in 2021-2022

Geometric increase in population coupled with rapid urbanization, industrialization and agricultural development has resulted in high impact on quality and quantity of water in India. Hence, the availability and the quality of the freshwater resources are the most pressing of the many environmental challenges in India (CPCB 2011). The quality of water is of vital concern for mankind, since it is directly linked with human welfare. Poor quality of water adversely affects the plant growth and human health (WHO 1984; Hem 1985). A number of studies on water quality have been carried out in different parts of India All these studies reveal that both rivers and groundwater in India are facing water quality issues. The state of Kerala, located in the south-western corner of India, is blessed with 44 rivers and heavy rainfall of ~ 3000 mm/year. However, most of the water in the rivers is quickly drained into the Arabian Sea due to the steep seaward sloping of the state. Hence, in addition to rivers, the groundwater is also utilized to meet the water requirements of the state. The increase in population, development activities, urbanization, change in land-use pattern, etc. has created a concern among the people of Kerala regarding both the river water and groundwater quality of various river basins

Quantum amplification of spin currents in cavity magnonics by a parametric drive induced long-lived mode

Cavity-mediated magnon-magnon coupling can lead to a transfer of spin-wave excitations between two spatially separated magnetic samples. We enunciate how the application of a two-photon parametric drive to the cavity can lead to stark amplification in this transfer efficiency. The recurrent multiphoton absorption by the cavity opens up an infinite ladder of accessible energy levels, which can induce higher-order transitions within the magnon Fock space. This is reflected in a heightened spin-current response from one of the magnetic samples when the neighboring sample is coherently pumped. The enhancement induced by the parametric drive can be considerably high within the stable dynamical region. Specifically, near the periphery of the stability boundary, the spin current is amplified by several orders of magnitude. Such striking enhancement factors are attributed to the emergence of parametrically induced strong coherences precipitated by a long-lived mode. While contextualized in magnonics, the generality of the principle would allow applications to energy transfer between systems contained in parametric cavities

A Metamaterial Backed Dipole Antenna for High Gain Directional Communications

The enhanced radiation performance of a dipole antenna backed by the split ring resonator-continuous wire pair array working in the H┴ excitation scenario is presented in this paper.  The H┴ excitation scenario of the metamaterial is used to get zero reflection phase resulting in enhanced gain performance. The two layer meta-structure along with the dipole is fabricated on a low cost substrate of dielectric constant 4.4 and height 1mm. The reflection properties of the metamaterial structure and its effect on the radiation performance of the dipole antenna are presented in this paper

Topological transitions in dissipatively coupled Su-Schrieffer-Heeger models

Non-Hermitian topological phenomena have gained much interest among physicists in recent years. In this paper, we expound on the physics of dissipatively coupled Su-Schrieffer-Heeger (SSH) lattices, specifically in systems with bosonic and electrical constituents. In the context of electrical circuits, we demonstrate that a series of resistively coupled LCR circuits mimics the topology of a dissipatively coupled SSH model. In addition, we foreground a scheme to construct dissipatively coupled SSH lattices involving a set of non-interacting bosonic oscillators weakly coupled to engineered reservoirs of modes possessing substantially small lifetimes when compared to other system timescales. Further, by activating the coherent coupling between bosonic oscillators, we elucidate the emergence of non-reciprocal dissipative coupling which can be controlled by the phase of the coherent interaction strength precipitating in phase-dependent topological transitions and skin effect. Our analyses are generic, apropos of a large class of systems involving, for instance, optical and microwave settings, while the circuit implementation represents the most straightforward of them.Comment: 10 pages, 9 figure

A Metamaterial Backed Dipole Antenna for High Gain Directional Communications

The enhanced radiation performance of a dipole antenna backed by the split ring resonator-continuous wire pair array working in the H┴ excitation scenario is presented in this paper.  The H┴ excitation scenario of the metamaterial is used to get zero reflection phase resulting in enhanced gain performance. The two layer meta-structure along with the dipole is fabricated on a low cost substrate of dielectric constant 4.4 and height 1mm. The reflection properties of the metamaterial structure and its effect on the radiation performance of the dipole antenna are presented in this paper

KvLQT1 and KCNE1 K+ channel gene polymorphisms in long QT syndrome

Long QT Syndrome (LQTS), a disorder of the cardiac repolarization process with prolongation of the QT interval (QTc ≥0.46 seconds), is an ion-channelopathy. Mutations in either KCNQ1 or KCNE1 genes are susceptible to LQTS. Hence, screening of KCNQ1 and KCNE1 genes is taken up to evaluate the genetic correlation of these genes in Long QT patients of Indian origin. A total of 33 Long QT Syndrome patients and 100 healthy subjects were enrolled for the present study. PCR-SSCP protocol was utilised for screening of KCNQ1 and KCNE1 genes followed by In-silico and statistical analysis. The clinical profile of the Long QT syndrome patients in our study revealed a higher percentage of females with the mean age also being higher in females when compared to males. The two variations (S546S and IVS13+36A>G) in KCNQ1 and the S38G polymorphism in KCNE1 gene were identified and their association with Long QT syndrome is being reported for the first time in Indian population. S546S is located in the KCNQ1 C terminus close to this domain and IVS13+36A>G is located in the intronic region in close proximity to the coding region for C-terminal domain; these may therefore affect the functional protein through non-assembly. S38G leads to a substitution of serine to glycine at 38th amino acid position (S38G) in the transmembrane domain of KCNE1. Our study reports compound heterozygosity/genetic compound ofS546S and IVS13+36A>G of KCNQ1 gene. Haplotype frequencies and linkage disequilibrium analysis revealed a significant association between the three biomarkers. Compound heterozygosity of the polymorphisms influence downstream signalling and KCNQ1-KCNE1 interactions

Grating-based Dipole Antenna Configuration for High Gain Directional Radiation characteristics

The experimental and simulation studies of the radiation performance enhancement of a dipole antenna using metal strip grating are presented in this paper. The subwavelength imaging configuration of the metal strip grating is utilized for enhancing the radiation performance of a dipole antenna working in the S-band. The resultant design shows a gain of 9 dBi and front to back ratio of the design is found to be -23 dB at resonance. The coupling between electric and magnetic resonances provides the necessary impedance matching performance when the antenna is brought in the vicinity of the grating

Grating-based Dipole Antenna Configuration for High Gain Directional Radiation characteristics

The experimental and simulation studies of the radiation performance enhancement of a dipole antenna using metal strip grating are presented in this paper. The subwavelength imaging configuration of the metal strip grating is utilized for enhancing the radiation performance of a dipole antenna working in the S-band. The resultant design shows a gain of 9 dBi and front to back ratio of the design is found to be -23 dB at resonance. The coupling between electric and magnetic resonances provides the necessary impedance matching performance when the antenna is brought in the vicinity of the grating