分类: 天文学 >> 天文学 提交时间: 2023-02-19
摘要: Dark matter has been a long-standing and important issue in physics, but direct evidence of its existence is lacking. This work aims to elucidate the mystery and show that the dark matter hypothesis is unnecessary. We can nicely reproduce the observed rotation curves using only conventional Newtonian dynamics based on experimental surface brightness profiles of several galaxies. Our success is based on realizing that the mass radial distribution follows a stretched exponential decay with a small exponent over a few hundred kiloparsecs. Our quantitative analysis indicates that for these four example galaxies, there is no need to invoke the hypothetical dark matter presently unknown to humans or the modified Newtonian dynamics (MOND) paradigm.
分类: 天文学 >> 天文学 提交时间: 2023-02-19
摘要: Dark matter has been a long-standing and important issue in physics, but direct evidence of its existence is lacking. This work aims to elucidate the mystery and show that the dark matter hypothesis is unnecessary. We can nicely reproduce the observed rotation curves using only conventional Newtonian dynamics based on experimental surface brightness profiles of several galaxies. Our success is based on realizing that the mass radial distribution follows a stretched exponential decay with a small exponent over a few hundred kiloparsecs. Our quantitative analysis indicates that for these four example galaxies, there is no need to invoke the hypothetical dark matter presently unknown to humans or the modified Newtonian dynamics (MOND) paradigm.
分类: 天文学 >> 天文学 提交时间: 2023-02-19
摘要: The physics potential of detecting $^8$B solar neutrinos is exploited at the Jiangmen Underground Neutrino Observatory (JUNO), in a model independent manner by using three distinct channels of the charged-current (CC), neutral-current (NC) and elastic scattering (ES) interactions. Due to the largest-ever mass of $^{13}$C nuclei in the liquid-scintillator detectors and the potential low background level, $^8$B solar neutrinos would be observable in the CC and NC interactions on $^{13}$C for the first time. By virtue of optimized event selections and muon veto strategies, backgrounds from the accidental coincidence, muon-induced isotopes, and external backgrounds can be greatly suppressed. Excellent signal-to-background ratios can be achieved in the CC, NC and ES channels to guarantee the $^8$B solar neutrino observation. From the sensitivity studies performed in this work, we show that one can reach the precision levels of 5%, 8% and 20% for the $^8$B neutrino flux, $\sin^2\theta_{12}$, and $\Delta m^2_{21}$, respectively, using ten years of JUNO data. It would be unique and helpful to probe the details of both solar physics and neutrino physics. In addition, when combined with SNO, the world-best precision of 3% is expected for the $^8$B neutrino flux measurement.
分类: 工程与技术科学 >> 工程与技术科学其他学科 提交时间: 2023-01-03 合作期刊: 《2022年第三届艺术设计、传播与工程科学研讨会》
摘要: Buildings carry people's emotional thoughts. Paper Bamboo House establishes an emotional connection between space and people through characteristic ecological materials, pays attention to people's true perception of buildings, and emphasizes the rhythm of architectural form and rhythm. The architectural design needs to explore the possibility of space existence from the regional culture, rebuild the relationship between the building and the surrounding environment, strive to create a harmonious building that coexists with nature, and practice the regional practice of low-carbon architecture. Advocate to use the comprehensive thinking of reason and art to explore the meaning of space and form.
分类: 医学、药学 >> 临床医学 分类: 生物学 >> 生物工程 分类: 物理学 >> 电磁学、光学、声学、传热、经典力学和流体动力学 提交时间: 2019-01-15
摘要: [Objective] Evaluate on the treatment efficacy and safety for transcranial magnetoelectric encephalopathy treatment instrument (brand name: AOBO Parkinson’s Treatment Instrument) treatmenting parkinson's disease. [Methods] Use methods of double center,randomized, double blind, self crossover, 22 Parkinson’s patients who met the inclusion criteria were randomly divided into A group and B group, then were carried on the curative effect analysis, and were observed therapeutic effect. [Results] The treatment group of 22 cases, basically cured in 0 cases, markedly effective in 9 cases, effective in 8 cases, ineffective in 5 cases. The total efficiency rate and total effective rate were 40.91% (9/22) or 77.27% (17/22) respectively. The control group of 22 cases, basically cured in 0 cases, markedly effective in 2 cases, effective in 3 cases, ineffective in 17 cases. The total efficiency rate and total effective rate were 9.09% (2/22) or 22.73% (5/22) respectively, the total effective rate and total effective rate in the treatment group were higher than those in the control group, the difference was statistically significant (P0.05); There was significant difference between the treatment group and the control group (p<0.05). [Conclusions] Transcranial magnetoelectric stimulation can significantly improve resting tremor, muscle rigidity, bradykinesia in patients with Parkinson’s disease and other symptoms, and the use of safety. "