Search for vector-like leptons at a Muon Collider

A feasibility study is performed for searching vector-like leptons at a muon collider, in the context of the "4321 model", an ultraviolet-complete model with rich collider phenomenology together with potential to explain recent existing some B physics measurements or anomalies. In this paper, we perform a Monte Carlo study with various machine learning techniques, and examine the projected sensitivity on vector-like leptons over a wide mass range at a TeV-scale muon collider. We find that a 3 TeV muon collider with only 10/fb of data can already be sensitive to cover the mass range of a vector-like lepton up to 1450 GeV.Comment: CPC Published Versio

Stochastic evolutionary game analysis of food cooperation among countries along the Belt and Road from the perspective of food security

IntroductionIn recent years, the combination of the public health crisis and the climate crisis has greatly weakened the resilience of food systems. The Belt and Road food cooperation will make outstanding contributions to consolidate food security and reduce global poverty in countries along the Belt and Road.MethodsThis paper constructs a three-party stochastic evolutionary game model from the perspective of food security, distinguishes the difference between large and small countries by calculating the cereal self-sufficiency rate, which studies the cooperation strategy with the Belt and Road cereal large countries, cereal small countries and regulatory committees as the object. In addition, we introduce the Gaussian white noise characteristics to characterize the stochastic disturbance of the game system. Then we combine the mathematical derivation of the stochastic evolutionary game analysis with the simulation method, examine the effect of the stochastic disturbance factors on the cooperation, and find out the factors that affect the cooperation. And finally verifies the model and proves the reasonableness and practicability of the model.ResultsThe stochastic evolutionary game model analyzes the interaction of stochastic disturbance and influencing factors from a dynamic perspective, and the stability of evolution is related to the strength of Gaussian white noise. The level of effort of large cereal countries and the incentives of regulatory committees can have a positive impact, but high income in small cereal countries can lead to instability in the strategic choices of other players.DiscussionTaking the countries along the Belt and Road as the research object, Gaussian white noise is introduced to describe the stochastic external environment, discriminate the stability of the game system through stochastic differential equations, and analyze the influencing factors of the dynamic behavioral strategies of the parties in combination with simulation methods. To improve the capacity of national food security governance and help improve the resilience of the world food system

Characterization of the Interaction between the Cohesin Subunits Rad21 and SA1/2

The cohesin complex is responsible for the fidelity of chromosomal segregation during mitosis. It consists of four core subunits, namely Rad21/Mcd1/Scc1, Smc1, Smc3, and one of the yeast Scc3 orthologs SA1 or SA2. Sister chromatid cohesion is generated during DNA replication and maintained until the onset of anaphase. Among the many proposed models of the cohesin complex, the ﾒcoreﾒ cohesin subunits Smc1, Smc3, and Rad21 are almost universally displayed as tripartite ring. However, other than its supportive role in the cohesin ring, little is known about the fourth core subunit SA1/SA2. To gain deeper insight into the function of SA1/SA2 in the cohesin complex, we have mapped the interactive regions of SA2 and Rad21 in vitro and ex vivo. Whereas SA2 interacts with Rad21 through a broad region (301ﾖ750 aa), Rad21 binds to SA proteins through two SA-binding motifs on Rad21, namely N-terminal (NT) and middle part (MP) SA-binding motif, located At 60-81 aa of the N-terminus and 383ﾖ392 aa of the MP of Rad21, respectively. The MP SA-binding motif is a 10 amino acid, a-helical motif. Deletion of these 10 amino acids or mutation of three conserved amino acids (L385, F389, and T390) in this ahelical motif significantly hinders Rad21 from physically interacting with SA1/2. Besides the MP SA-binding motif, the NT SAbinding motif is also important for SA1/2 interaction. Although mutations on both SA-binding motifs disrupt Rad21-SA1/2 interaction, they had no apparent effect on the Smc1-Smc3-Rad21 interaction. However, the Rad21-Rad21 dimerization was reduced by the mutations, indicating potential involvement of the two SA-binding motifs in the formation of the two-ring handcuff for chromosomal cohesion. Furthermore, mutant Rad21 proteins failed to significantly rescue precocious chromosome separation caused by depletion of endogenous Rad21 in mitotic cells, further indicating the physiological significance of the two SA-binding motifs of Rad21

Heat treatment of small heat shock proteins α-crystallin and Hsp16.3: structural changes vs. chaperone-like activity

Both α-crystallin from bovine eye lens and Hsp16.3 from Mycobacterium tuberculosis are members of the small heat shock protein family. They were preincubated at 100°C for 15 min and then cooled on ice immediately. The chaperone-like activities of preheated proteins were measured at 37° using DTT-treated insulin B chains as substrates. Both preheated proteins exhibited greatly enhanced chaperone-like activities, accompanied with almost unchanged secondary structures and surface hydrophobicity but with a minor change in tertiary structures. The dramatically enhanced chaperone-like activities of preheated a-crystallin and Hsp16.3 may have resulted from the irreversible change in the tertiary structure as detected by near-UV CD spectra

Calpain-1 Cleaves Rad21 To Promote Sister Chromatid Separation ▿

Defining the mechanisms of chromosomal cohesion and dissolution of the cohesin complex from chromatids is important for understanding the chromosomal missegregation seen in many tumor cells. Here we report the identification of a novel cohesin-resolving protease and describe its role in chromosomal segregation. Sister chromatids are held together by cohesin, a multiprotein ring-like complex comprised of Rad21, Smc1, Smc3, and SA2 (or SA1). Cohesin is known to be removed from vertebrate chromosomes by two distinct mechanisms, namely, the prophase and anaphase pathways. First, PLK1-mediated phosphorylation of SA2 in prophase leads to release of cohesin from chromosome arms, leaving behind centromeric cohesins that continue to hold the sisters together. Then, at the onset of anaphase, activated separase cleaves the centromeric cohesin Rad21, thereby opening the cohesin ring and allowing the sister chromatids to separate. We report here that the calcium-dependent cysteine endopeptidase calpain-1 is a Rad21 peptidase and normally localizes to the interphase nuclei and chromatin. Calpain-1 cleaves Rad21 at L192, in a calcium-dependent manner. We further show that Rad21 cleavage by calpain-1 promotes separation of chromosome arms, which coincides with a calcium-induced partial loss of cohesin at several chromosomal loci. Engineered cleavage of Rad21 at the calpain-cleavable site without activation of calpain-1 can lead to a loss of sister chromatid cohesion. Collectively, our work reveals a novel function of calpain-1 and describes an additional pathway for sister chromatid separation in humans

Crystallization and X-ray diffraction analysis of the β-ketoacyl-acyl carrier protein reductase FabG from Aquifex aeolicus VF5

FabG from A. aeolicus, a putative component of fatty-acid synthase II, has been overexpressed, purified and crystallized. Diffraction data have been collected to 1.8 Å resolution

Analysis on Spatial Characteristics of Supply–Demand Relationship of Amenities in Expanding Central Urban Areas—A Case Study of Huai’an, China

Supply and demand for amenities in expanding urban areas undergo continuous adjustment. In this study, we explored the relationship between supply of and demand for amenities in expanding urban areas to evaluate the rationality and effectiveness of amenity distribution, improve urban governance, and promote urban accessibility and justice, thereby facilitating sustainable urban development. We selected the central urban area of Huai’an City, China as the research area. We used point-of-interest data, Baidu population heatmap data, and residential housing prices to develop supply and demand indices for amenities and analyze the spatial characteristics of the supply of and demand for amenities in expanding urban areas. The results revealed that (1) the supply–demand relationship in the study area was mainly balanced, followed by relationships in which supply was lower than demand, and the relationships of supply exceeding demand is less, accounting for 68.35%, 26.06%, and 5.59%, respectively. (2) The core of the old urban area and the areas surrounding the old urban area had high supply–demand balance, the transitional and new urban areas had less supply than demand, and the developing urban areas had low supply–demand balance; the supply–demand relationship of amenities followed a clear circular distribution pattern. (3) The Chinese government’s continuous renewal of old urban areas has made the quantitative proportion of supply and demand components be positively correlated with the oldness of urban development, which has enlightening effects on the construction of other cities. Finally, we developed suggestions for adjusting the distribution of amenities in the central urban area of Huai’an to facilitate high-quality development in this area