Detection of ultra-high resonance contrast in vapor cell atomic clocks

We propose and demonstrate a novel detection scheme of clock signals and obtain an ultra-high resonance contrast above 90%. The precision of the signal's detection and the signal-to-noise ratio (SNR) of atomic clock signal is improved remarkably. The frequency stability in terms of Allan deviation has been improved by an order for the new detection under the equivalent conditions. We also investigate density effect which produces the splitting of the transmission peak and consequently a narrower linewidth of Ramsey fringes.Comment: 5 pages, 4 figure

Annealing tunable charge density wave order in a magnetic kagome material FeGe

In the magnetic kagome metal FeGe, a charge density wave (CDW) order emerges inside the antiferromagnetic phase, providing a fertile playground to investigate the interplay between charge and magnetic orders. Here, we demonstrate that the CDW order, as well as magnetic properties, can be reversibly tuned on a large scale through post-growth annealing treatments. The antiferromagnetic and CDW transitions vary systematically as functions of both the temperature and the time period of annealing. Long-range CDW order with a maximum $T_{\mathrm{CDW}}$ and a minimum $T_{\mathrm{N}}$ can be realized in crystals annealed at \SI{320}{\degreeCelsius} for over 48 h. Using magnetization and magnetostrictive coefficient measurements, it is found that the CDW transition is rather stable against an external magnetic field and spin-flop transition. On the other hand, the critical field for spin-flop transition is significantly reduced in the long-range ordered CDW phase. Our results indicate that the CDW in FeGe is immune to variations in magnetic orders, while the magnetocrystalline anisotropy energy and the corresponding magnetic ground state can be altered significantly by the charge order. These findings provide crucial clues for further investigation and a better understanding of the nature of the CDW order in FeGe.Comment: 8 pages, 4 figure

Wind Power, Hydropower and Thermal Power Combined Low-Carbon Maintenance Optimization Based on Continuous Hidden Markov Model

[Introduction] In the context of the new power system, low-carbon maintenance of wind turbines and coordinated maintenance with conventional wind turbine generator systems (WTGS) need to be solved urgently. In this paper, taking into account the impact of multi-attribute meteorological factors and low carbon and economic needs, an optimization model for wind power, hydropower and thermal power combined low-carbon maintenance based on continuous hidden Markov model is established. [Method] Firstly, dynamic tracking of wind farm maintenance capacity was realized by taking rainfall, wind speed and lightning hazard degree as the observation sequence, taking maintenance capacity as hidden state sequence, and using continuous hidden Markov model (CHMM) process. Then, an optimization model for wind power, hydropower and thermal power combined low-carbon maintenance was constructed by taking the optimal maintenance capacity as the decision-making basis, taking the minimum total cost as the optimization objective, and taking the maintenance constraints and system control constraints into consideration. Finally, took the IEEE30-node system as an example. [Result] The results show that the proposed model has more significant economic benefits and low carbon characteristics. [Conclusion] The research in this paper has high theoretical value for the operation and maintenance of WTGS, and has strong engineering applicability

Clinical characteristics of tracheobronchomalacia complicated with pulmonary infection in children and the significance of electronic fiberoptic bronchoscopy in diagnosis and treatment

Objective To analyze the clinical features of children with tracheobronchomalacia （TBM） complicated with pulmonary infection，and to explore the significance of fiberoptic bronchoscopy in the diagnosis and treatment of this disease. Methods Clinical data of 236 children admitted to our hospital due to recurrent pulmonary infection were collected. Among them， 37 children were diagnosed with TBM by fiberoptic bronchoscopy. Clinical features of TBM and fiberoptic bronchoscopy results were analyzed. The differences between TBM and non-TBM children were statistically compared. Results The proportion of TBM children aged<1 year was high （30/37）. The average age of TBM children was significantly younger than that of non-TBM counterparts， and the average length of hospital stay of TBM children was significantly longer than that of non-TBM counterparts， and the differences were statistically significant （both P < 0.05）. The main manifestations of TBM and non-TBM children were cough， wheezing and recurrent respiratory tract infection， and there were no statistical differences in the male-to-female ratio （all P > 0.05）. Fiberoptic bronchoscopy found mild and moderate TBM at a single site in TBM children， and favorable outcomes were obtained. Conclusion TBM is one of the important factors of recurrent pulmonary infection and wheezing in young children. It is challenging to identify the symptoms of TBM. Bronchoscopy is beneficial to timely diagnosis and treatment

Anti-inflammatory Effect of Heat-sensitive Moxibustion via the NF-κB Signaling Pathway on Cerebral Ischemia/Reperfusion Injury in Rats

Ischemic stroke is universally acknowledged as a common cause of long-term disability or even death. Suspended moxibustion, an indirect form of moxibustion, is when moxibustion is placed superfcially over the skin without being in contact with it. Some researchers have used this method to treat stroke patients, but strong evidence of its therapeutic effectiveness is lacking.However, the effect of traditional suspended moxibustion has recently been improved with the development of heat-sensitive suspended moxibustion. Our previous studies showed that moxibustion for 35 min provided a more effective treatment strategy than moxibustion for 15 min, and moxibustion by 35 min with tail temperature increase had a better outcome than that without, however,the mechanism underlying the effect is not clear. In this study, we treated the stroke rats with moxibustion by 35min and divided them into non-heat sensitive moxibustion(NHSM) group and heat sensitive moxibustion (HSM) group according to difference in the tail temperature increase, then we compared the effect and investigated the mechanisms between NHSM and HSM. We found that HSM signifcantly decreased tail-flick latency, increased neurological function score, decreased infarct volume, reduced inflammatory cells,decreased the expression of inflammatory factor ICAM-1 and reduced the expression of NF-κB p65 and p-IKKα/β in rats with focal cerebral ischemia/reperfusion injury. Our experimental fndings revealed that HSM exerted its anti-inflammatory and neuroprotective effects from MCAO-induced injury by decreasing the expression of the NF-κB signaling pathway

Multiband effects in thermoelectric and electrical transport properties of kagome superconductors AAV3_3Sb5_5 (AA = K, Rb, Cs)

We studied the effects of multiband electronic structure on the thermoelectric and electrical transport properties in the normal state of kagome superconductors $A$V$_3$Sb$_5$ ($A$ = K, Rb, Cs). In all three members, the multiband nature is manifested by sign changes in the temperature dependence of the Seebeck and Hall resistivity, together with sublinear response of the isothermal Nernst and Hall effects to external magnetic fields in the charge ordered state. Moreover, ambipolar transport effects appear ubiquitously in all three systems, giving rise to sizable Nernst signal. Finally, possible origins of the sign reversal in the temperature dependence of the Hall effect are discussed.Comment: 8 pages, 5 figures. To appear in New Journal of Physic