Radiative and non-radiative effects of a substrate on localized plasmon resonance of particles

Experiments have shown strong effects of some substrates on the localized plasmons of metallic nano particles but they are inconclusive on the affecting parameters. Here we have used Discrete Dipole Approximation in conjunction with Sommerfeld integral relations to explain the effect of the substrates as a function of the parameters of incident radiation. The radiative coupling can both quench and enhance the resonance and its dependence on the angle and polarization of incident radiation with respect to the surface is shown. Non-radiative interaction with the substrate enhances the plasmon resonance of the particles and can shift the resonances from their free-space energies significantly. The non-radiative interaction of the substrate is sensitive to the shape of particles and polarization of incident radiation with respect to substrate. Our results show that plasmon resonances in coupled and single particles can be significantly altered from their free-space resonances and are quenched or enhanced by the choice of substrate and polarization of incident radiation.Comment: 14 pages, 4 figure

Defence Expenditure and Economic Growth: Evidence from India

This thesis work presents both mathematical models and a simulation approach to get more insight to the R&D Project Portfolio Execution problem. It gives special care to finding the optimal number of projects to run simultaneously in a portfolio in order to get the maximum monetary gain, and give the factors that affect the most this number. This report tries as well to give the best simulation of resources behaviour inside an R&D department, and takes a stage-gate model for the projects. The proposed mathematical model is a Non-Linear Mixed Integer Program that is hard to solve. A simplification lead to a less complicated Mixed Integer Program that is easier to solve. But in order to have an insight of the whole complexity of the problem, a simulation platform has been implemented. Thanks to its low computation cost, it allowed to have a big number of simulations and draw some conclusions about the initial question. The simulation platform also allows to see the influence of different factors on the number of projects that should be executed in parallel in R &D departments, which was hard to do using the mathematical models.  Detta examensarbete presenterar både matematiska modeller och en simuleringsplattform för att få mer insikt i R & D Project Portfolio Execution problem. Målet är att beräkna det optimala antalet projekt att köra samtidigt i en portfölj och hitta de faktorer som har störst påverkan på detta. Rapporten försöker också att ge den bästa simuleringen av resursersbeteende i R & D avdelningar. Den föreslagna matematiska modellen är ett icke-linjärt Mixed Integer Program som är svårt att lösa. En simplifiering leder till en mindre komplicerad Mixed Integer Program som är lättare att lösa, men för att få en inblick i hela problemets komplexitet har en simuleringsplattform implementerats. Tack vare dess låga beräkningskostnad, är det möjligt att köra ett stort antal simuleringar och dra vissa slutsatser om den inledande frågan. Användandet av en simuleringsplattform gör det också möjligt att se påverkan av olika faktorer på antalet projekt som ska köras parallellt i R & D -avdelningar, som hade varit svårt att göra med matematisk modellering

Many-body approach to low-lying collective excitations in a BEC approaching collapse

An approximate many-body theory incorporating two-body correlations has been employed to calculate low-lying collective multipole frequencies in a Bose-Einstein condensate containing $A$ bosons, for different values of the interaction parameter $\lambda=\frac{Aa_{s}}{a_{ho}}$. Significant difference from the variational estimate of the Gross-Pitaevskii equation has been found near the collapse region. This is attributed to two-body correlations and finite range attraction of the realistic interatomic interaction. A large deviation from the hydrodynamic model is also seen for the second monopole breathing mode and the quadrupole mode for large positive $\lambda$.Comment: 8 pages, 2 figure

Antiviral medicinal plants of India as a potential tool against COVID-19: A review with ethno scientific evidence

Indian traditional medicinal systems are one of the oldest therapeutic systems in the world. Medicinal and aromatic plants play a dominant role in Indian traditional medicinal systems. Traditionally, many medicinal plants are used in India for their therapeutic relevance so much so that they have acquired a significant role in Indian religion as well. Many of these plants have proven antiviral effects. This review documents up-to-date information about many such medicinal herbs used in India which have got pharmacological significance in fighting viral infections. These plants surely have the potential to provide protection against Covid-19. The review presents a list of such plants along with their chemical ingredients and possible modes of action against the respective viral diseases. All information has been obtained by consulting the databases of Scopus, PubMed, Science Direct, Elsevier, Springer and relevant research papers and reports on COVID-19. The cited medicinal plants are used extensively in India as herbal remedies. The use of these plants is validated in light of research papers citing their ethnobotanical uses, important active principles and modes of action of the of medicinally important natural products. The plants listed have great potential to fight COVID-19 and other viral infections. Many of these are immunity boosters providing strength to the body to control the onset of diseases

Post kidney transplant infections with special reference to cytomegalovirus

Background: The burden of infectious disease is high among kidney transplant recipients because of concomitant immunosuppression. Methods: Study was a retrospective and prospective cohort study. The study was conducted for a period of 12 months and 30 transplant recipients were included. Results: Males comprised 86.66% of the study population. The mean age of the recipients was 37.96 years. UTI was the most common post-transplant infection observed in 15 patients (50%) of 30 patients. E. Coli infection was most predominant (50%) causing UTI. 5 patients (16.66%) in this study developed tuberculosis after renal transplantation. Two patients (6.66%) developed CMV infection in the study. Two patients (6.66%) developed COVID-19 infection in the study. Two patients (6.66%) developed herpes infection post-transplant. One patient (3.33%) in the study developed cryptococcal meningitis. One patient (3.33%) developed hepatitis C after 18 years of transplant. One patient (3.33%) developed hepatitis B after 10 years of transplant. Three patients (10%) developed lower respiratory tract infection and developed acute respiratory distress. Three patients (10%) had developed acute graft rejection within first year after transplantation. There are total of 13 deaths (43.33%) among 30 patients all of which were secondary to infections. Total of 4 patients among the 13 deaths had chronic graft rejection. Most common cause of death was tuberculosis (38.46%) followed by UTI (23%) and Lower respiratory tract infection (23%). Conclusions: The incidence of infections is relatively higher in kidney transplant recipients when compared to general populations due to immunosuppression

The underpinning factors affecting the classroom air quality, thermal comfort and ventilation in 30 classrooms of primary schools in London

The health and academic performance of children are significantly impacted by air quality in classrooms. However, there is a lack of understanding of the relationship between classroom air pollutants and contextual factors such as physical characteristics of the classroom, ventilation and occupancy. We monitored concentrations of particulate matter (PM), CO2 and thermal comfort (relative humidity and temperature) across five schools in London. Results were compared between occupied and unoccupied hours to assess the impact of occupants and their activities, different floor coverings and the locations of the classrooms. In-classroom CO2 concentrations varied between 500 and 1500 ppm during occupancy; average CO2 (955 ± 365 ppm) during occupancy was ∼150% higher than non-occupancy. Average PM10 (23 ± 15 μgm-3), PM2.5 (10 ± 4 μgm-3) and PM1 (6 ± 3 μg m-3) during the occupancy were 230, 125 and 120% higher than non-occupancy. Average RH (29 ± 6%) was below the 40–60% comfort range in all classrooms. Average temperature (24 ± 2 °C) was >23 °C in 60% of classrooms. Reduction in PM10 concentration (50%) by dual ventilation (mechanical + natural) was higher than for PM2.5 (40%) and PM1 (33%) compared with natural ventilation (door + window). PM10 was higher in classrooms with wooden (33 ± 19 μg m-3) and vinyl (25 ± 20 μgm-3) floors compared with carpet (17 ± 12 μgm-3). Air change rate (ACH) and CO2 did not vary appreciably between the different floor levels and types. PM2.5/PM10 was influenced by different occupancy periods; highest value (∼0.87) was during non-occupancy compared with occupancy (∼0.56). Classrooms located on the ground floor had PM2.5/PM10 > 0.5, indicating an outdoor PM2.5 ingress compared with those located on the first and third floors (300 m3) classroom showed ∼33% lower ACH compared with small-volume (100–200 m3). These findings provide guidance for taking appropriate measures to improve classroom air quality

Removal of hexavalent chromium using chitosan prepared from shrimp shells

Contamination of the aqueous environment by heavy metals and due to the discharge of metal containing effluents into the water bodies is one of the environmental issues of the century. Thus, in this work, the main concern has been the preparation of chitin and chitosan from the raw materials of shrimp shells and the characterization of the prepared chitosan by field emission scanning electron microscopy (FESEM) and Fourier transform infrared spectroscopy (FTIR). The work was then shifted to investigate the potentiality of Cr+6 adsorption with the prepared chitosan. The controlled parameters of adsorption process were studied. The percentage of Cr+6 removal using the shrimp chitosan was 64.29%.Keywords: Shrimp shells, chitosan, adsorption, chiti

On the flare induced seismicity in the active region NOAA 10930 and related enhancement of global waves in the sun

A major flare (of class X3.4) occurred on 13 December 2006 in the active region NOAA 10930. The energy released during flares is also known to induce acoustic oscillations in the Sun. Here, we analyze the line-of-sight velocity patterns in this active region during the X3.4 flare using the Dopplergrams obtained by GONG instrument. We have also analyzed the disk-integrated velocity observations of the Sun obtained by GOLF instrument onboard SOHO spacecraft as well as full-disk collapsed velocity signals from GONG observations during this flare to study any possible connection between the flare related changes seen in the local and global velocity oscillations in the Sun. We apply wavelet transform to the time series of the localized velocity oscillations as well as the global velocity oscillations in the Sun spanning the flare event. The line-of-sight velocity shows significant enhancement in some localized regions of the penumbra of this active region during the flare. The affected region is seen to be away from the locations of the flare ribbons and the hard X-ray footpoints. The sudden enhancement in this velocity seems to be caused by the Lorentz force driven by the "magnetic jerk" in the localized penumbral region. Application of wavelet analysis to these flare induced localized seismic signals show significant enhancement in the high-frequency domain (5-8 mHz) and a feeble enhancement in the p-mode oscillations (2-5 mHz) during the flare. On the other hand, the wavelet analysis of GOLF velocity data and the full-disk collapsed GONG velocity data spanning the flare event indicate significant post-flare enhancements in the high-frequency global velocity oscillations in the Sun. We find indications of a connection between flare induced localized seismic signals and the excitation of global high-frequency oscillations in the Sun.Comment: 29 pages, 7 figures, To appear in The Astrophysical Journa