The beam energy measurement system for the Beijing electron-positron collider

The beam energy measurement system (BEMS) for the upgraded Beijing electron-positron collider BEPC-II is described. The system is based on measuring the energies of Compton back-scattered photons. The relative systematic uncertainty of the electron and positron beam energy determination is estimated as 2 \cdot 10^{-5}. The relative uncertainty of the beam's energy spread is about 6 %

Precision Measurement of the Proton Flux in Primary Cosmic Rays from Rigidity 1 GV to 1.8 TV with the Alpha Magnetic Spectrometer on the International Space Station

A precise measurement of the proton flux in primary cosmic rays with rigidity (momentum/charge) from 1 GV to 1.8 TV is presented based on 300 million events. Knowledge of the rigidity dependence of the proton flux is important in understanding the origin, acceleration, and propagation of cosmic rays. We present the detailed variation with rigidity of the flux spectral index for the first time. The spectral index progressively hardens at high rigidities.</p

Periodicities in the Daily Proton Fluxes from 2011 to 2019 Measured by the Alpha Magnetic Spectrometer on the International Space Station from 1 to 100 GV

We present the precision measurement of the daily proton fluxes in cosmic rays from May 20, 2011 to October 29, 2019 (a total of 2824 days or 114 Bartels rotations) in the rigidity interval from 1 to 100 GV based on 5.5×109 protons collected with the Alpha Magnetic Spectrometer aboard the International Space Station. The proton fluxes exhibit variations on multiple timescales. From 2014 to 2018, we observed recurrent flux variations with a period of 27 days. Shorter periods of 9 days and 13.5 days are observed in 2016. The strength of all three periodicities changes with time and rigidity. The rigidity dependence of the 27-day periodicity is different from the rigidity dependences of 9-day and 13.5-day periods. Unexpectedly, the strength of 9-day and 13.5-day periodicities increases with increasing rigidities up to ∼10 GV and ∼20 GV, respectively. Then the strength of the periodicities decreases with increasing rigidity up to 100 GV.</p

DMP1 Processing is Essential to Dentin and Jaw Formation

Dentin matrix protein 1 (DMP1), an acidic protein that is essential to the mineralization of bone and dentin, exists as proteolytically processed fragments in the mineralized tissues. In this study, we characterized the tooth and jaw phenotypes in transgenic mice containing no wild-type DMP1, but expressing a mutant DMP1 in which Asp213, a residue at one cleavage site, was replaced by Ala213 (named “Dmp1-KO/D213A-Tg” mice). The teeth and mandible of Dmp1-KO/D213A-Tg mice were compared with those of wild-type, Dmp1-knockout (Dmp1-KO), and Dmp1-KO mice expressing the normal Dmp1 transgene. The results showed that D213A-DMP1 was not cleaved in dentin, and the expression of D213A-DMP1 failed to rescue the defects in the dentin, cementum, and alveolar bones in the Dmp1-KO mice. These findings indicate that the proteolytic processing of DMP1 is essential to the formation and mineralization of dentin, cementum, and jaw bones