Determination of the chromospheric quiet network element area index and its variation during 2008-2011

Generally it has been considered that the plages and sunspots are the main contributors to the solar irradiance. There are small scale structures on the sun with intermediate magnetic fields that could also contribute to the solar irradiance. It has not yet been quantified how much of these small scale structures contribute to the solar irradiance and how much it varies over the solar cycle. In this paper, we used Ca II K images obtained from the telescope installed at Kodaikanal observatory. We report a method to separate the network elements from the background structure and plage regions. We compute the changes in the network element area index during the minimum phase of solar cycle and part of the ascending phase of cycle 24. The measured area occupied by the network elements is about 30% and plages less than 1% of the solar disk during the observation period from February 2008-2011. During the extended period of minimum activity it is observed that the network element area index decreases by about 7% compared to the area occupied by the network elements in 2008. A long term study of network element area index is required to understand the variations over the solar cycle.Comment: 12 pages, 9 Figures, Accepted for publication in RA

Mitigating the source-side channel vulnerability by characterization of photon statistics

Quantum key distribution (QKD) theoretically offers unconditional security. Unfortunately, the gap between theory and practice threatens side-channel attacks on practical QKD systems. Many well-known QKD protocols use weak coherent laser pulses to encode the quantum information. These sources differ from ideal single photon sources and follow Poisson statistics. Many protocols, such as decoy state and coincidence detection protocols, rely on monitoring the photon statistics to detect any information leakage. The accurate measurement and characterization of photon statistics enable the detection of adversarial attacks and the estimation of secure key rates, strengthening the overall security of the QKD system. We have rigorously characterized our source to estimate the mean photon number employing multiple detectors for comparison against measurements made with a single detector. Furthermore, we have also studied intensity fluctuations to help identify and mitigate any potential information leakage due to state preparation flaws. We aim to bridge the gap between theory and practice to achieve information-theoretic security.Comment: Comments and suggestions are welcome

Indian Journal of Animal Science: a scientometric assessment and application of Lotka's Law (2015-2020)

This paper analyse the scientometric attributes of the publications that appeared in the Indian Journal of Animal Science, a scientific journal in animal breeding, physiology, nutrition, dairying, animal production and fisheries, etc. from 2015 to 2020. The bibliographic records of publications were retrieved from the Web of Science database and retrieved 1720 research papers. The collected data were analysed by using Web of Science and biblioshiny software. The results revealed that the maximum number of research papers were published during the year 2020 and also received maximum citations in the same year. The research contribution also followed the Lotka’s Law and found that the maximum contribution was given by the researchers of ICAR - Indian Veterinary Research Institute, Bareilly and the highest research publications were from India

Quantum key distribution with multiphoton pulses: An advantage

In this article, we introduce a quantum key distribution protocol for the line of sight channels based on coincidence measurements. We present a proof-of-concept implementation of our protocol. We show that using coincidence measurements to monitor multi-photon pulses results in a higher secure key rate over longer distances for such channels. This key rate is higher than popular implementations of quantum key distribution protocol based on BB84, for example, the GLLP analysis [Quant. Info. Comput. \textbf{4}, 325 (2004)]. In the experiment, we could generate around $74 \%$ more key bits per signal pulse as compared to the GLLP analysis of BB84 protocol with similar parameters and equal value of mean photon number.Comment: 12 pages, 4 figures and 3 tables. Final accepted version (Accepted for publication in OSA Continuum

COVID-19 lockdown induced changes in NO2 levels across India observed by multi-satellite and surface observations

© Author(s) 2021. This work is distributed under the Creative Commons Attribution 4.0 License.We have estimated the spatial changes in NO 2levels over different regions of India during the COVID-19 lockdown (25 March-3 May 2020) using the satellite-based tropospheric column NO 2observed by the Ozone Monitoring Instrument (OMI) and the Tropospheric Monitoring Instrument (TROPOMI), as well as surface NO 2concentrations obtained from the Central Pollution Control Board (CPCB) monitoring network. A substantial reduction in NO 2levels was observed across India during the lockdown compared to the same period during previous business-as-usual years, except for some regions that were influenced by anomalous fires in 2020. The reduction (negative change) over the urban agglomerations was substantial (~20 %-40 %) and directly proportional to the urban size and population density. Rural regions across India also experienced lower NO 2values by ~15 %-25 %. Localised enhancements in NO 2associated with isolated emission increase scattered across India were also detected. Observed percentage changes in satellite and surface observations were consistent across most regions and cities, but the surface observations were subject to larger variability depending on their proximity to the local emission sources. Observations also indicate NO 2enhancements of up to~25%during the lockdown associated with fire emissions over the north-east of India and some parts of the central regions. In addition, the cities located near the large fire emission sources show much smaller NO 2reduction than other urban areas as the decrease at the surface was masked by enhancement in NO 2due to the transport of the fire emissions.Peer reviewedFinal Published versio

MENGGUNAKAN METODE DISKUSI UNTUK MENINGKATKAN KEMAMPUAN MENULIS PADA SISWA KELAS IV SD NEGERI NEUHEUN KABUPATEN ACEH BESAR

Banda Ace