Discrete Dynamical Systems: A Brief Survey

Dynamical system is a mathematical formalization for any fixed rule that is described in time dependent fashion. The time can be measured by either of the number systems - integers, real numbers, complex numbers. A discrete dynamical system is a dynamical system whose state evolves over a state space in discrete time steps according to a fixed rule. This brief survey paper is concerned with the part of the work done by José Sousa Ramos [2] and some of his research students. We present the general theory of discrete dynamical systems and present results from applications to geometry, graph theory and synchronization

First principles design of divacancy defected graphene nanoribbon based rectifying and negative differential resistance device

We have elaborately studied the electronic structure of 555-777 divacancy (DV) defected armchair edged graphene nanoribbon (AGNR) and transport properties of AGNR based two-terminal device constructed with one defected electrode and one N doped electrode, by using density functional theory and non-equilibrium Green's function based approach. The introduction of 555-777 DV defect into AGNRs, results in a shifting of the {\pi} and {\pi}* bands towards the higher energy value which indicates a shifting of the Fermi level towards the lower energy. Formation of a potential barrier, very similar to that of conventional p-n junction, has been observed across the junction of defected and N doped AGNR. The prominent asymmetric feature of the current in the positive and negative bias indicates the diode like property of the device with high rectifying efficiency within wide range of bias voltages. The device also shows robust negative differential resistance (NDR) with very high peak-to-valley ratio. The analysis of the shifting of the energy states of the electrodes and the modification of the transmission function with applied bias provides an insight into the nonlinearity and asymmetry observed in the I-V characteristics. Variation of the transport properties on the width of the ribbon has also been discussed.Comment: 28 Pages, 12 Figures and 1 tabl

Technical Efficiency of Freshwater Aquaculture and its Determinants in Tripura, India

Freshwater aquaculture is an important and promising sector of the economy of Tripura State. The biophysical potential for growth in freshwater aquaculture in the state is still far from exhaustion and a faster development is required to meet the growth in demand for fish. This paper has assessed the level of technical efficiency and its determinants of small-scale fish production in the West Tripura district of the state of Tripura, India. The study is based on the cross-sectional primary data collected from 101 fish farmers through a multi-stage random sampling method. The paper has employed stochastic production frontier approach, and has followed both one-stage and two-stage procedures to analyze the determinants of TE. The TE ranges between 0.21 and 0.96 with mean of 0.66 and median of 0.71. The study has revealed the Cobb-Douglas form of stochastic frontier production function is more dependable than that of translog form under the farming conditions in the West Tripura district of Tripura state. One-stage procedure with technical inefficiency model gives reliable estimates of coefficients of stochastic frontier production function than that of two-stage procedure. Seed quality has been found as an important determinant of TE. The study has suggested that the state government needs to play a role to ascertain the supply of quality fish fingerlings at adequate time and quantity to the farmers in the study area.Agricultural and Food Policy,

Study of Phytochemical, Antioxidant and Antimicrobial Activity of Artocarpus heterophyllus

In today’s world, search for natural medicines is increasing as a result of drug resistance of pathogens and also due to negative consequences of antibiotic. Presence of phytochemicals, antioxidant potential and antimicrobial activity of Artocarpus heterophyllus was carried out in this study. Leaf of this plant was subjected to warm extraction with three different solvents namely methanol, aqueous methanol and ethyl acetate. Leaf extract showed the presence of coumarin, alkaloid, terpenoid in methanol solvent; tannin, coumarin, saponin in aqueous methanol extract and coumarin, terpenoids in ethyl acetate solvent. Further, antimicrobial activity was assessed through disc diffusion method with six pathological bacteria and two fungi strains in four different concentrations of plant extract. Largest ZOI of 16mm was obtained against B. subtilis in 200mg/ml concentration for ethyl acetate extract. Antioxidant potential was measured by DPPH (Diphenyl-2-picrylhydrazyl) assay. DPPH free radical Scavenging Activity was expressed in % inhibition with L Ascorbic acid as standard and leaf extract in methanol showed the best activity

Enhanced bone marrow derived mesenchymal stem cell differentiation when isolated and expanded with human platelet rich plasma and differentiation media is supplemented with vitamin D

Vitamin D3 is well known to be involved in bone formation during foetal development and has been shown to be actively involved from gestational day 13 during foetal rat development [1]. Vitamin D3 and its associated enzyme 1-alpha-hydroxylase a member of the cytochrome P450 super family and encoded for by the gene CYP27B1. In this study we supplemented osteogenic media with vitamin D at a concentration of 10-4M and differentiated for 21 days with samples analysed by means of quantitative alizarin red assay and qPCR for the bone markers RUNX2, ALPL and HPRT

Non-timber forestry products on marginal lands

Non-timber forestry products on marginal land

Investigating Electronic, Optical, and Phononic Properties of Bulk γ-M<inf>2</inf>ON<inf>2</inf>and β-M<inf>7</inf>O<inf>8</inf>N<inf>4</inf>(M = Hf and Zr) Insulators Using Density Functional Theory

Hafnium and zirconium oxynitrides have similar properties, yet a consolidated investigation of their intrinsic properties has not been carried out. In this paper, we perform first-principles density functional theory calculations of γ- and β-phase hafnium and zirconium oxynitrides, which show that the γ-M2ON2(M = Hf and Zr) is an indirect band-gap (Eg) insulator, while the β-M7O8N4has a "pseudo-direct" type of Eg. β-phase has higher Egthan γ-phase, with concomitant disappearance of the conduction band tail. Optical properties in γ-M2ON2show that the anisotropy is negligible, and the optical constant values are in the range of other superhard materials. Phonon calculations present peculiar characteristics such as a small phonon band gap in γ-Hf2ON2and imaginary phonon frequencies in β-phases relating to lattice instability. The phononic properties are unfavorable for their potential use as an absorber material of the hot carrier solar cell-an emerging photovoltaic concept

Reactive arthritis post-SARS-CoV-2

Reactive arthritis (ReA) following bacterial infection from the urogenital and gastrointestinal tract is widely described but is not typical post-viral infections. This report presents the second case of ReA after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in the United States. A 45-year-old black male with chronic low back pain was hospitalized for 45 days with coronavirus disease 2019 (COVID-19), complicated due to the development of multiorgan failure managed with intubation, extracorporeal membrane oxygenation, and hemodialysis. He was subsequently discharged to an acute rehabilitation facility where he complained of new-onset pain in his shoulders, left elbow, and left knee three weeks after a negative SARS-CoV-2 test. He was readmitted from his acute rehabilitation facility due to recurrent fever and the development of a swollen, warm left knee. Laboratory studies at readmission showed elevated inflammatory markers, negative extensive infectious disease workup, and aseptic inflammatory left knee synovial fluid without crystals. Testing returned negative for most common antibodies seen in immune-mediated arthritides (e.g., rheumatoid arthritis, systemic lupus erythematosus), as well as for common respiratory and gastrointestinal tract pathogens responsible for viral arthritis. The multidisciplinary inpatient medical team deemed the clinical presentation and laboratory findings most consistent with ReA. The patient received a course of oral corticosteroids, followed by a second course due to the recurrence of symptoms weeks after initial treatment and recovery. The current body of medical literature on SARS-CoV-2 pathophysiology supports plausible mechanisms on how this infection may induce ReA. Such a scenario should be considered in the differential of COVID-19-recovered patients presenting with polyarthritis as prompt steroid treatment may help patient recovery