Distance-regular Cayley graphs over (pseudo-) semi-dihedral groups

Distance-regular graphs are a class of regualr graphs with pretty combinatorial symmetry. In 2007, Miklavi\v{c} and Poto\v{c}nik proposed the problem of charaterizing distance-regular Cayley graphs, which can be viewed as a natural extension of the problem of characterizing strongly-regular Cayley graphs (or equivalently, regular partial difference sets). In this paper, we provide a partial characterization for distance-regular Cayley graphs over semi-dihedral groups and pseudo-semi-dihedral groups, both of which are $2$-groups with a cyclic subgroup of index $2$.Comment: 21 page

Global hybrid simulations of soft X-ray emissions in the Earth’s magnetosheath

Earth’s magnetopause is a thin boundary separating the shocked solar wind plasma from the magnetospheric plasmas, and it is also the boundary of the solar wind energy transport to the magnetosphere. Soft X-ray imaging allows investigation of the large-scale magnetopause by providing a two-dimensional (2-D) global view from a satellite. By performing 3-D global hybrid-particle-in-cell (hybrid-PIC) simulations, we obtain soft X-ray images of Earth’s magnetopause under different solar wind conditions, such as different plasma densities and directions of the southward interplanetary magnetic field. In all cases, magnetic reconnection occurs at low latitude magnetopause. The soft X-ray images observed by a hypothetical satellite are shown, with all of the following identified: the boundary of the magnetopause, the cusps, and the magnetosheath. Local X-ray emissivity in the magnetosheath is characterized by large amplitude fluctuations (up to 160%); however, the maximum line-of-sight-integrated X-ray intensity matches the tangent directions of the magnetopause well, indicating that these fluctuations have limited impact on identifying the magnetopause boundary in the X-ray images. Moreover, the magnetopause boundary can be identified using multiple viewing geometries. We also find that solar wind conditions have little effect on the magnetopause identification. The Solar wind Magnetosphere Ionosphere Link Explorer (SMILE) mission will provide X-ray images of the magnetopause for the first time, and our global hybrid-PIC simulation results can help better understand the 2-D X-ray images of the magnetopause from a 3-D perspective, with particle kinetic effects considered

Effect of night shift work on metabolic syndrome in adults who suffered from earthquake stress in early life

ObjectiveTo examine the role of night shift work on the risk of metabolic syndrome (MetS) in adults suffered from earthquakes prenatally or as infants and to analyse the effect of stress on factors that influence MetS in this population.MethodsWe included 870 subjects from 2014 to 2015. All subjects work as miners for the Kailuan Mining Group and were born were living in Tangshan. Participants were classified into two groups on basis of their work schedules: day shift and night shift. They were further classified into the prenatal exposure group, the infancy exposure group, and the control group based on their age during the Tangshan earthquake. This study was conducted 38 years after the earthquake. Participants’ general demographic data, smoking and drinking habits, as well as work schedules were collected. All participants’ sleep status was assessed with the Pittsburgh Sleep Quality Index. The measurement of all subjects’ waist circumference and blood pressure was made, and triglycerides, fasting blood glucose, high-density lipoproteins, and low-density lipoproteins were measured by collecting blood samples. The definition of MetS was made after the guidelines for preventing and controlling type 2 diabetes in China (2017 Edition).ResultsA total of 187 (21.5%) workers were determined to have MetS. The incidence of MetS was greatly higher in night shift workers who were exposed to an earthquake during infancy than in day shift workers (χ2 = 8.053, p = 0.005). A multivariate logistic regression analysis displayed male participants had a higher risk develop MetS than female participants (p = 0.042, OR = 0.368, 95% CI = 0.140, 0.965). Current smokers (p = 0.030, OR = 1.520, 95%CI = 1.042, 2.218) and participants who sleep fewer than 7 h per night (p = 0.015, OR = 1.638, 95%CI = 1.101, 2.437) had a higher risk of MetS. Prenatal earthquake stress was also a risk element for MetS (p = 0.012, OR = 1.644, 95%CI = 1.115, 2.423).ConclusionThe risk of MetS is significantly higher in night shift workers exposed to earthquake stress during infancy than day shift workers. Earthquake exposure during pregnancy is an independent risk factor for MetS. Smoking and sleeping less than 7 h have a higher risk of MetS than the control group