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318 results on '"Aryal B"'

6. Spatial Orientation of Spin Vectors of Blue-shifted Galaxies

Author

Yadav, S. N., Aryal, B., and Saurer, W.

Subjects
Astrophysics - Astrophysics of Galaxies
Abstract

We present the analysis of the spin vector orientation of 5$\,$987 SDSS galaxies having negative redshift from $-$87.6 to $-$0.3 km$\,$s$^{-1}$. Two dimensional observed parameters are used to compute three dimensional galaxy rotation axes by applying `position angle--inclination' method. We aim to examine the non-random effects in the spatial orientation of blue-shifted galaxies. We generate 5$\times$10$^6$ virtual galaxies to find expected isotropic distributions by performing numerical simulations. We have written MATLAB program to facilitate the simulation process and eliminate the manual errors in the process. Chi-square, auto-correlation, and the Fourier tests are used to examine non-random effects in the polar and azimuthal angle distributions of the galaxy rotation axes. In general, blue-shifted galaxies show no preferred alignments of galaxy rotation axes. Our results support Hierarchy model, which suggests a random orientation of angular momentum vectors of galaxies. However, local effects are noted suggesting gravitational tidal interaction between neighboring galaxies., Comment: 7 pages, 17 figures, submitted to Ap&SS

Published
2016

7. An Interdisciplinary Approach to Connecting Quantitative and Science Curricula and Pedagogy in an Undergraduate Program

Author

Dame, L., Aryal, B., Huq, A., and Prat-Resina, X.

Abstract

Students entering health sciences programs may face challenges on their road to successful completion and possible entry to medical school in the area of preparedness in quantitative skills. At our institution, faculty analyzed evidence of these challenges including performance on the ACT Math Test, an in-house math placement test and quantitative tasks for physics and chemistry courses. The authors have used the ARCS (Attention, Relevance, Confidence, Satisfaction) conceptual framework developed by John M. Keller to examine a collaborative effort by our faculty from mathematics, chemistry and physics to design and deliver an interdisciplinary quantitative curriculum in the first 2 years. Preliminary results show high levels of attention, an improvement in student perceptions regarding the relevance of math to science, significant improvements to student confidence in their ability to learn and apply algebra, and reasons for student satisfaction. Faculty reflections indicate that this was a significant and rewarding effort.

Published
2019
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9. A Study of chiral property of field galaxies

Author

Aryal, B., Pandey, R., and Saurer, W.

Subjects
Astrophysics - Galaxy Astrophysics, Astrophysics - Cosmology and Extragalactic Astrophysics
Abstract

We present an analysis of the chiral property of 1,621 field galaxies having radial velocity 3,000 km/s to 5,000 km/s . A correlation between the chiral symmetry breaking and the preferred alignment of galaxies in the leading and trailing structural modes is studied using chi-square, auto-correlation and the Fourier tests. We noticed a good agreement between the random alignment of the position angle (PA) distribution and the existence of chirality in both the leading and trailing arm galaxies. Chirality is found stronger for the late-type spirals (Sc, Scd, Sd and Sm) than that of the early-types (Sa, Sab, Sb and Sbc). A significant dominance (17% $\pm$ 8.5%) of trailing modes is noticed in the barred spirals. In addition, chirality of field galaxies is found to remain invariant under the global expansion. The PA-distribution of the total trailing arm galaxies is found to be random, whereas preferred alignment is noticed for the total leading arm galaxies. It is found that the rotation axes of leading arm galaxies tend to be oriented perpendicular the equatorial plane. A random alignment is noticed in the PA-distribution of leading and trailing spirals., Comment: arXiv admin note: substantial text overlap with arXiv:1010.5585

Published
2013

10. Estimation of mass and cosmological constant of nearby spiral galaxies using galaxy rotation curve

Author

Aryal, B., Pandey, R., Baral, N., Khanal, U., and Saurer, W.

Subjects
Astrophysics - Cosmology and Extragalactic Astrophysics
Abstract

An expression for rotational velocity of a test particle around the central mass in the invariant plane is derived. For this, a line element of Schwarzschild de-Sitter space-time is used to study the effect of cosmological constant ($\Lambda$) on the motion of both massive and massless particles. Using rotation curve data of 15 nearby spiral and barred spiral galaxies, we estimated the mass and $\Lambda$ of the galaxy. The mass of the galaxies are found to lie in the range 0.13-7.60 $\times$ 10$^{40}$ kg. The cosmological constant ($\Lambda$) is found to be negative ($-$0.03 to $-$0.10 $\times$ 10$^{-40}$ km$^{-2}$), suggesting the importance of anti-de Sitter space in the local bubble. Possible explanation of the results will be discussed., Comment: 11 pages, 20 figures, submitted to BASI

Published
2013

12. Winding sense of galaxies around the Local Supercluster

Author

Aryal, B.

Subjects
Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

We present an analysis of the winding sense (S and Z-shaped) of 1\,621 field galaxies that have radial velocity between 3\,000 km s$^{-1}$ to 5\,000 km s$^{-1}$. The preferred alignments of S- and Z-shaped galaxies are studied using chi-square, auto-correlation and the Fourier tests. We classified total galaxies into 32 subsamples and noticed a good agreement between the position angle (PA) distribution of S- and Z-shaped galaxies. The homogeneous distribution of the S- and Z-shaped galaxies is noticed for the late-type spirals (Sc, Scd, Sd and Sm) than that of the early-types (Sa, Sab, Sb and Sbc). A significant dominance of S-mode galaxies is noticed in the barred spirals. A random alignment is noticed in the PA-distribution of Z- and S-mode spirals. In addition, homogeneous distribution of the S- and Z-shaped galaxies is found to be invariant under the global expansion. The PA-distribution of the total S-mode galaxies is found to be random, whereas preferred alignment is noticed for the total Z-mode galaxies. It is found that the galactic planes of Z-mode galaxies tend to lie in the equatorial plane., Comment: 16 pages, 8 figures, accepted on 22 Oct 2010 by RAA

Published
2010
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22. Age and Gender Differences in COVID 19 Morbidity and Mortality in Nepal

Author

Dhimal, M. L., Rana, N., Aryal, B., Adhikari, S. K., Shrestha, R., Gyanwali, P., and Dhimal, M.

Subjects
General Medicine
Abstract

Background The global health community has emphasized the importance of reporting epidemiological data by age and sex groups in the COVID-19 pandemic. However, age and sex disaggregated data of COVID-19 cases and deaths are rarely reported. Such data are very crucial for public to make truly informed choices about their own diseases risk and also for governments for public policy response. Objective To assess age and gender difference among COVID-19 cases and deaths in Nepal. Method This is a retrospective study which uses public data on COVID-19 cases and deaths released by Ministry of Health and Population, Government of Nepal from January to November, 2020. The data analysis was carried out using SPPS software version 26. Result Nepal reported 233,452 confirmed cases and 1,566 deaths of COVID-19 from 23 January 2020 to 30 November 2020. We found statistically significant differences on COVID-19 cases by age and gender in Nepal with higher number of cases among males of economically active age groups (20-60 years). Similarly, we found significant difference in COVID-19 mortality with more death occurred among male group compared to female group and with highest number of deaths among the people of above 60 years. Furthermore, we found differences in cases and deaths among provinces. Conclusion The age and gender differences in COVID cases and deaths in Nepal indicates needs of considering age and sex groups seriously while planning for testing, case management and vaccination against COVID-19 infections in Nepal.

Published
2020

23. Nitrous oxide emission in altered nitrogen cycle and implications for climate change.

Author

Aryal, B, Gurung, R, Camargo, AF, Fongaro, G, Treichel, H, Mainali, B, Angove, MJ, Ngo, HH, Guo, W, Puadel, SR, Aryal, B, Gurung, R, Camargo, AF, Fongaro, G, Treichel, H, Mainali, B, Angove, MJ, Ngo, HH, Guo, W, and Puadel, SR

Abstract

Natural processes and human activities play a crucial role in changing the nitrogen cycle and increasing nitrous oxide (N2O) emissions, which are accelerating at an unprecedented rate. N2O has serious global warming potential (GWP), about 310 times higher than that of carbon dioxide. The food production, transportation, and energy required to sustain a world population of seven billion have required dramatic increases in the consumption of synthetic nitrogen (N) fertilizers and fossil fuels, leading to increased N2O in air and water. These changes have radically disturbed the nitrogen cycle and reactive nitrogen species, such as nitrous oxide (N2O), and have impacted the climatic system. Yet, systematic and comprehensive studies on various underlying processes and parameters in the altered nitrogen cycle, and their implications for the climatic system are still lacking. This paper reviews how the nitrogen cycle has been disturbed and altered by anthropogenic activities, with a central focus on potential pathways of N2O generation. The authors also estimate the N2O-N emission mainly due to anthropogenic activities will be around 8.316 Tg N2O-N yr-1 in 2050. In order to minimize and tackle the N2O emissions and its consequences on the global ecosystem and climate change, holistic mitigation strategies and diverse adaptations, policy reforms, and public awareness are suggested as vital considerations. This study concludes that rapidly increasing anthropogenic perturbations, the identification of new microbial communities, and their role in mediating biogeochemical processes now shape the modern nitrogen cycle.

Published
2022

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