On the evaluation of the Gottfried sum and d̄−ū asymmetry with the use of the TMM method

In this paper, we obtain the integrated flavor asymmetry of the sea quarks in the proton, [Formula: see text], with the help of the truncated moments approach elaborated in our previous papers. We use the difference between the light sea-quark distributions [Formula: see text] extracted from Drell–Yan (DY) NuSea/E866 measurements of the cross-section ratio [Formula: see text] and from the recent global analysis of deep inelastic scattering (DIS) [Formula: see text] data incorporating the reanalyzed neutron structure function. In our analysis, we also include the most recent DY data from the Fermilab SeaQuest/E906 experiment.

Study on the linear absent section ratio (L-ASR) of earthen sites and anthropogenic influence from the perspective of population density

Having extremely high artistic, scientific and social values, earthen sites are widely distributed in China and are important human cultural relic resources. Due to accumulated natural erosions (from rain and wind) and human activities (destructive activities of human beings in history and modern times), however, earthen sites have been greatly damaged, and many sections have even been absent, so that they are seriously threatened by extinction. Under these circumstances, acquiring the conservation status of earthen sites is a vital prerequisite for the subsequent targeted protection. In this paper, as a world-renowned heritage site, the castles of the Ming Great Wall located in Qinghai Province were selected as the research object. A novel indicator, namely the linear absent section ratio (L-ASR), was proposed, and its value was classified into five levels to quantitatively characterize the specific conservation status of such sites, including excellent (E) (0–10%), good (G) (10–25%), fair (F) (25–50%), poor (P) (50–75%), and very poor (VP) (75–100%). Based on the assessment results, the castles with excellent status constituted the minimum proportion, while the castles with very poor status represented the largest percentage, reflecting the grave situation of earthen sites. Furthermore, by applying population distribution models to the linear fitting combined with the population density (PD), a positive correlation between PD and L-ASR was obtained to reveal the anthropogenic influence on the destruction of earthen sites. Principal component analysis (PCA) was utilized to provide a far richer understanding of which factors correlate most strongly with deterioration. This study provides a new thought to quantitatively characterize the preservation conditions of earthen sites and also indicates the effect of human activities on the damage of earthen sites from a population density perspective, which is potentially used for the analysis of more various types of architecture with different construction techniques. Hence, this approach is beneficial to the overall damage assessment of earthen sites, and also meaningful to their further preservation and protective planning.

The great Chinese fireball of December 22, 2020

On December 22, 2020, at about 23h 23m 33s UTC a very bright fireball was seen in the sky of southeastern China. The fireball lasted for several seconds and ended with an atmospheric explosion that was detected by US surveillance satellites. According to CNEOS’s data, the fireball moved with a mean speed of 13.6 km/s and exploded at an altitude of about 35.5 km (Lat. $$31.9^{\circ }$$ 31 . 9 ∘ N; Long. $$96.2^{\circ } $$ 96 . 2 ∘ E). In this paper we estimate the atmospheric trajectory, the heliocentric orbit and the strewn fields for different mass/section ratio of the fragments. The trajectory was about from north to south and with low inclination ($$5^{\circ } \pm 2^{\circ }$$ 5 ∘ ± 2 ∘ ) with respect to the local surface. The explosion height appears consistent with a fragmented rocky body, and the heliocentric orbit supports an asteroidal origin. The probable strewn field extends between two points with coordinates ($$+31.3^\circ $$ + 31 . 3 ∘ N; $$96.3^\circ $$ 96 . 3 ∘ E) and ($$+30.3^\circ $$ + 30 . 3 ∘ N; $$96.5^\circ $$ 96 . 5 ∘ E), for a total area of about 4000 $$\text {km}^2$$ km 2 . This large extension is a direct consequence of the low inclination of the trajectory. Given the unknown uncertainty of the CNEOS’s data, these results should be taken with caution.

Study on the Linear Vanishing Section Ratio of Earthen Sites and Anthropogenic Influence from the Perspective of Population Density

Having extremely high artistic, scientific and social values, earthen sites are widely distributed in China, which are important cultural relic resources of mankind. Due to accumulated natural erosions and human activities, however, earthen sites have been greatly damaged and have even vanished many sections, so that they are seriously threatened by extinction. In the circumstances, acquiring the conservation status of earthen sites is a vital prerequisite for the subsequent targeted protection. In this paper, as a world-renowned heritage site, the castles of the Ming Great Wall located in Qinghai Province were selected as the research object. A novel indicator namely the linear vanishing section ratio (L-VSR) was proposed and its value was classified as five levels to quantitatively characterize the specific conservation status of such sites. Based on the assessment results, the castles at the excellent status constituted the minimum proportion, while the castles at the very poor status represented the largest percentage, reflecting the grave situation of earthen sites. Furthermore, applying population distribution models into the linear fitting combined with the population density (PD), the positive correlation between PD and L-VSR was obtained to reveal the anthropogenic influence on the destruction of earthen sites. This study provides a new thought to quantitatively characterize the preservation conditions of earthen sites and also indicates the effect of human activities on the damage of earthen sites from the population perspective. Hence, it is beneficial to the overall damage assessment of earthen sites, and also meaningful to their further preservation and protective planning.