Publications by authors named "A K Paul"

2,734 Publications

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Emergence of universality in the transmission dynamics of COVID-19.

Sci Rep 2021 09 23;11(1):18891. Epub 2021 Sep 23.

Department of Physics, Indian Institute of Technology Kanpur, Kanpur, Uttar Pradesh, 208016, India.

The complexities involved in modelling the transmission dynamics of COVID-19 has been a roadblock in achieving predictability in the spread and containment of the disease. In addition to understanding the modes of transmission, the effectiveness of the mitigation methods also needs to be built into any effective model for making such predictions. We show that such complexities can be circumvented by appealing to scaling principles which lead to the emergence of universality in the transmission dynamics of the disease. The ensuing data collapse renders the transmission dynamics largely independent of geopolitical variations, the effectiveness of various mitigation strategies, population demographics, etc. We propose a simple two-parameter model-the Blue Sky model-and show that one class of transmission dynamics can be explained by a solution that lives at the edge of a blue sky bifurcation. In addition, the data collapse leads to an enhanced degree of predictability in the disease spread for several geographical scales which can also be realized in a model-independent manner as we show using a deep neural network. The methodology adopted in this work can potentially be applied to the transmission of other infectious diseases and new universality classes may be found. The predictability in transmission dynamics and the simplicity of our methodology can help in building policies for exit strategies and mitigation methods during a pandemic.
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http://dx.doi.org/10.1038/s41598-021-98302-3DOI Listing
September 2021

How severe acute respiratory syndrome coronavirus-2 aerosol propagates through the age-specific upper airways.

Phys Fluids (1994) 2021 Aug 19;33(8):081911. Epub 2021 Aug 19.

School of Mechanical, Medical and Process Engineering, Faculty of Engineering, Queensland University of Technology, Brisbane 4000, Australia.

The recent outbreak of the COVID-19 causes significant respirational health problems, including high mortality rates worldwide. The deadly corona virus-containing aerosol enters the atmospheric air through sneezing, exhalation, or talking, assembling with the particulate matter, and subsequently transferring to the respiratory system. This recent outbreak illustrates that the severe acute respiratory syndrome (SARS) coronavirus-2 is deadlier for aged people than for other age groups. It is evident that the airway diameter reduces with age, and an accurate understanding of SARS aerosol transport through different elderly people's airways could potentially help the overall respiratory health assessment, which is currently lacking in the literature. This first-ever study investigates SARS COVID-2 aerosol transport in age-specific airway systems. A highly asymmetric age-specific airway model and fluent solver (ANSYS 19.2) are used for the investigation. The computational fluid dynamics measurement predicts higher SARS COVID-2 aerosol concentration in the airway wall for older adults than for younger people. The numerical study reports that the smaller SARS coronavirus-2 aerosol deposition rate in the right lung is higher than that in the left lung, and the opposite scenario occurs for the larger SARS coronavirus-2 aerosol rate. The numerical results show a fluctuating trend of pressure at different generations of the age-specific model. The findings of this study would improve the knowledge of SARS coronavirus-2 aerosol transportation to the upper airways which would thus ameliorate the targeted aerosol drug delivery system.
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http://dx.doi.org/10.1063/5.0061627DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8450910PMC
August 2021

Evolution of transition metal charge states in correlation with the structural and magnetic properties in disordered double perovskites CaLaFeRuO (0.5 ≤ ≤ 2).

Phys Chem Chem Phys 2021 Sep 22. Epub 2021 Sep 22.

Department of Chemistry, National Institute of Technology Kurukshetra, Kurukshetra-136119, India.

A series of disordered CaLaFeRuO, CaLaFeRuO and LaFeRuO double perovskites were prepared by the solid-state reaction method and investigated by neutron powder diffraction, X-ray absorption near-edge structure (XANES) analysis at the Ru-K edge, Mössbauer spectroscopy, DC magnetization and resistivity measurements. All compounds crystallize in the orthorhombic crystal structure with the space group down to 3 K, showing a random distribution of Fe and Ru at the B site. Thermogravimetric analysis indicates oxygen deficiency in the Ca-rich and formal oxygen hyperstoichiometry in the La-rich members of the present series. While Mössbauer spectra verify the Fe state for all compositions, the XANES study reveals a variable Ru oxidation state which decreases with increasing La content. The end member actually is a Ru/Ru compound with possibly some cation vacancies. From magnetic susceptibility and neutron diffraction measurements, the presence of a G-type antiferromagnetic ordering was observed with a drastic increase in transition temperature from 275 K (CaLaFeRuO) to 570 K (LaFeRuO). Mössbauer spectroscopy confirms the presence of long-range ordering but, due to local variations in the exchange interactions, the magnetic states are microscopically inhomogeneous. All the samples are variable range hopping semiconductors. A complex interplay between structural features, charge states, anion or cation defects, and atomic disorder determines the magnetic properties of the present disordered 3d/4d double perovskite series.
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http://dx.doi.org/10.1039/d1cp02318gDOI Listing
September 2021

Real-time observation of nucleation and growth of Au on CdSe quantum dot templates.

Sci Rep 2021 Sep 21;11(1):18777. Epub 2021 Sep 21.

Guangdong Technion-Israel Institute of Technology, Shantou, 515063, Guangdong, China.

Semiconductor quantum dot (QD) arrays can be useful for optical devices such as lasers, solar cells and light-emitting diodes. As the size distribution influences the band-gap, it is worthwhile to investigate QDs prepared using different solvents because each of them could influence the overall morphology differently, depending on the ligand network around individual QDs. Here, we follow the nucleation and growth of gold (Au) on CdSe QD arrays to investigate the influence of surface ligands and thereby realized interparticle distance between QDs on Au growth behaviour. We particularly emphasize on the monolayer stage as the Au decoration on individual QDs is expected at this stage. Therefore, we sputter-deposit Au on each QD array to investigate the morphological evolution in real-time using time-resolved grazing-incidence small-angle X-ray scattering (GISAXS). The growth kinetics - independent of the template - signifies that the observed template-mediated nucleation is limited only to the very first few monolayers. Delicate changes in the Au growth morphology are seen in the immediate steps following the initial replicated decoration of the QD arrays. This is followed by a subsequent clustering and finally a complete Au coverage of the QD arrays.
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http://dx.doi.org/10.1038/s41598-021-97485-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8455570PMC
September 2021

Influence of Single Bouts of Aerobic Exercise on Dual-Tasking Performance in Healthy Adults.

J Mot Behav 2021 Sep 21:1-10. Epub 2021 Sep 21.

Department of Physical Therapy, Radford University Carilion, Roanoke, Virginia, USA.

Dual-tasking performance (DTP) is critical for most real-life activities. Interventions to improve DTP would be clinically valuable. This study investigated effects of single-bouts of two different aerobic exercises on the performance of Extended cognitive Timed-Up and Go (ETUGcog), a dual-task test involving concurrent performance of a physical (ETUG) and cognitive (counting backwards serial 7 s) task. Twenty-two adults performed single bouts of high-intensity interval training (HIIT) and moderate-intensity exercise (MIE), separately. ETUGcog was performed before, immediately following, and 24 hours after each exercise. Number and rates of correct serial 7 s were significantly higher 24 hours after HIIT, with no difference in times to complete ETUGcog. No such effects were found for MIE. Single bouts of HIIT could provide delayed improvements in DTP.
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http://dx.doi.org/10.1080/00222895.2021.1980366DOI Listing
September 2021
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