The breakdown of both strange metal and superconducting states at a pressure-induced quantum critical point in iron-pnictide superconductors.

Here we report the first observation of the concurrent breakdown of the strange metal (SM) normal state and superconductivity at a pressure-induced quantum critical point in Ca10(Pt4As8)((Fe0.97Pt0.03)2As2)5 superconductor. We find that, upon suppressing the superconducting state, the power exponent (α) changes from 1 to 2, and the slope of the temperature-linear resistivity per FeAs layer (A□) gradually diminishes. At a critical pressure, A□ and superconducting transition temperature (Tc) go to zero concurrently, where a quantum phase transition from a superconducting state with a SM normal state to a non-superconducting Fermi liquid state occurs. Scaling analysis reveals that the change of A□ with Tc obeys the relation of Tc ~ (A□)0.5, similar to what is seen in other chemically doped unconventional superconductors. These results suggest that there is a simple but powerful organizational principle of connecting the SM normal state with the high-Tc superconductivity.

An analysis of escalator-related injuries in metro stations in China, 2013-2015.

In order to reduce the probability and severity of escalator-related injuries and enhance the safety of passengers, this study analyzed 950 escalator-related injuries in Guangzhou metro stations to identify the characteristics and the risk factors associated with escalator-related injuries in China. The data extracted from Management Information System of Guangzhou Metro covers the site and time of the accident, age and gender of the victims, escalator condition and injury information. The results from the statistical analysis indicated that the majority of the escalator-related injuries was caused by failing to stand firm (287 cases, 30.2%), passengers carrying out other tasks (214 cases, 22.5%), not holding the handrail (168 cases, 17.7%) and unhealthy passengers (18 cases, 9.3%). Age was associated with all factors except for need for an ambulance and the distribution law of these factors differed with age groups. Elderly passengers (aged 66 years and above) accounted for the highest proportion of all injuries (49.1%), and failing to stand firm (18.63%) was the main cause of escalator-related injuries of elderly passengers. The most common mechanism of injury for all age groups was a fall, accounting for (51.0%) injuries. Proportion of injuries caused by a fall increased with age, whereas injuries attributed to entrapment decreased. Female passengers (65.9%) were more likely to be involved escalator-related injuries than male passengers (34.1%), while male passengers were more likely to have accidents caused by unhealthy physical condition than female passengers. These results based on the analysis of current accident data can be used to help metro operation corporation develop effective injury prevention measures and document the need for continued improvement of escalator safety in metro stations.