IOSR-JAP   Volume-17 ~ Issue-4 ~ Jul. – Aug. 2025

ABSTRACT: The uranium-238 radioactive series is a well-known multi-step decay chain involving multiple alpha and beta-negative decays, ultimately resulting in the stable lead-206 isotope. In this work, we use computational simulations with Monte Carlo method to analyze the stochastic timing of decay events and to evaluate hypothetical decay pathways. Initially, by considering only mass and charge conservation, we identify 3,003 theoretical decay chains. However, many of these chains are unphysical due to energy constraints and nuclear stability. By incorporating additional nuclear physics principles, such as decay energy and nuclear shell stability, we confirm that only the well-established uranium-238 decay series is physically possible. This approach demonstrates a practical application of computational techniques to analyze nuclear decay chains.

Keywords: Uranium-238; Radioactive series; Nuclear decay; Simulation; Monte Carlo method.

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[3]. N. Moromoto, Y. Kawai, K. Terada, Et Al. Uranium–Lead Systematics Of Lunar Basaltic Meteorite Northwest Africa 2977. Mass Spectrometry 2023; 2: A0115.
[4]. X. Dai, J.H.F.L. Davies, Z. Yuan, Et Al. A Mesozoic Fossil Lagerstätte From 250.8 Million Years Ago Shows A Modern-Type Marine Ecosystem. Science 2023; 379: 567-572.
[5]. A.L. Thomas, G.M. Henderson, P. Deschamps, Et Al. Penultimate Deglacial Sea-Level Timing From Uranium/Thorium Dating Of Tahitian Corals. Science 2009; 324: 1186-1189.

ABSTRACT: This comprehensive study evaluated the dosimetric and clinical outcomes of three-dimensional conformal radiotherapy (3D-CRT), intensity-modulated radiotherapy (IMRT), and volumetric modulated arc therapy (VMAT) in the treatment of localized prostate cancer. The analysis included 13 intermediate-risk prostate cancer patients (PSA levels 4-15 ng/mL, clinical stages T2a-T2c) who underwent treatment planning using five-field and seven-field 3D-CRT, five-field and seven-field IMRT, and single-arc VMAT (RapidArc) techniques. Detailed dosimetric......

Keywords: Prostate cancer, VMAT, IMRT, 3D-CRT, dosimetric analysis, PTV coverage, rectal sparing, cost-effectiveness, radiotherapy planning, treatment techniques

[1] Tanaka K, Sato H, Watanabe Y. Advanced VMAT Techniques For Prostate Cancer In Japanese Patients: A Multicenter Analysis. ISOR J Radiat Oncol. 2023;12(3):45-60.
[2] Yamada S, Nakamura T. Cost-Effectiveness Analysis Of Modern Radiotherapy Techniques In Tokyo Metropolitan Hospitals. Jpn J Clin Oncol. 2022;52(8):789-801.
[3] ESTRO Guidelines Committee. Prostate Cancer Radiotherapy: 2023 Clinical Practice Guidelines. Radiother Oncol. 2023;178:109-120.
[4] Kobayashi T, Suzuki M, Yamamoto H. Comparative Analysis Of 3D-CRT In Elderly Japanese Prostate Cancer Patients. ISOR J Radiat Oncol. 2021;10(2):33-44.
[5] Hashimoto M, Et Al. Organ Sparing In Prostate VMAT: Japanese Single-Institution Experience. Med Phys Jpn. 2022;18(4):112-125.

ABSTRACT: This paper shows the current theories that support or refute the end of the universe.Using the Friedmann equations, which are derived from Einstein's field equations, this work examines the expansion, curvature, and the roles of energy and dark matter in determining the fate of the universe. The equations were examined using the assumptions of homogeneity and isotropy in conjunction with observational data from projects such as WMAP and COBE, and......

Keywords: Friedmann equations, critical density, curvature of the universe, dark matter, dark energy, big freeze, big crunch.

[1] Cervantes-Cota, J. L., & Smoot, G. (2011). Cosmology Today-A Brief Review. Arxiv Preprint Arxiv:1107.1789
[2] Hirvonen, V. (N.D.-A). The Friedmann Equations Explained: A Complete Guide. Profound Physics.
Https://Profoundphysics.Com/The-Friedmann-Equations-Explained-A-Complete-Guide/
[3] 1: A Brief History Of The Universe With A Focus On The Domination Of... | Download Scientific Diagram. (N.D.-B).
Https://Www.Researchgate.Net/Figure/A-Brief-History-Of-The-Universe-With-A-Focus-On-The-Domi Nation-Of-Its-Different_Fig1_309730463
[4] Critical Density: Cosmos. Critical Density | COSMOS. (N.D.). Https://Astronomy.Swin.Edu.Au/Cosmos/C/Critical+Density

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