Probing Operator Spreading via Floquet Engineering in a Superconducting Circuit.

Operator spreading, often characterized by out-of-time-order correlators (OTOCs), is one of the central concepts in quantum many-body physics. However, measuring OTOCs is experimentally challenging due to the requirement of reversing the time evolution of systems. Here we apply Floquet engineering to investigate operator spreading in a superconducting 10-qubit chain. Floquet engineering provides an effective way to tune the coupling strength between nearby qubits, which is used to demonstrate quantum walks with tunable couplings, reversed time evolution, and the measurement of OTOCs. A clear light-cone-like operator propagation is observed in the system with multiple excitations, and has a nearly equal velocity as the single-particle quantum walk. For the butterfly operator that is nonlocal (local) under the Jordan-Wigner transformation, the OTOCs show distinct behaviors with (without) a signature of information scrambling in the near integrable system.

Blending control method of lower limb exoskeleton toward tripping-free stair climbing.

Tripping frequently occurs when an individual climbs the stairs with improper foot clearance. Among older adults, falling down the stairs accounts for over 10% of accidental deaths. This paper proposes an exoskeleton control method that blends human-dominant and exoskeleton-dominant control to prevent tripping. The blending controller not only allows the exoskeleton to track the pilot's movements and provide power assistance during regular walking, but also allows the exoskeleton to help the pilot avoid dangers in some cases. An online path planning method is used to generate a safe trajectory in the exoskeleton-dominant mode to help the pilot correct their running trajectory. The controller provides the pilot with adjustment spaces to adapt to sudden changes in the motion mode and enable active self-regulation. The simulations verified the effectiveness of the proposed blending method. Experiments showed that the robot should be involved in the pilot's movements when the foot clearance exceed the safety threshold to prevent tripping.

[Features and advances of Morse taper connection in oral implant].

Dental implants have been widely accepted as a predictable and reliable tool for dental reconstruction with the development of the economy. The design of implant-abutment connections has influence on mechanical properties and biological characteristics of implants. There are two types of implant-abutment connections, the external and the internal connections. Morse taper connection is one of the internal connections and its conical shape creates significant friction via the high propensity of parallelism between the two structures within the joint space. Several studies showed that Morse taper connection performed well in terms of survival rate, stability, bacterial seal and marginal bone loss. Recently, clinical studies indicate implants combining Morse taper connection with platform switching are helpful in reducing marginal bone absorption. This review aims at analyzing the features and advantages of Morse taper connection.

Chronic periodontitis and the risk of erectile dysfunction: a systematic review and meta-analysis.

The objective of this study is to evaluate the association between chronic periodontitis (CP) and the risk of erectile dysfunction (ED). Electronic search using PubMed, Embase and the Cochrane Library was carried out for observational studies, longitudinal, cohort, case-control and epidemiological studies on humans, published up to December 2015. Manual searches were also performed. Odds ratios (ORs) and corresponding 95% confidence intervals (CIs) were used to estimate the association between CP and the risk of ED. Methodological quality assessment was carried out using the Newcastle-Ottawa Quality Assessment Scale. Four case-control studies and one cross-sectional studies involving 213, 006 participants were included. Based on the random-effects model, analyses of all studies showed that CP was associated with an increased risk of ED (OR=2.28, 95% CI: 1.50-3.48). There was heterogeneity among the studies (P<0.001, I2=97.8%). Estimates of total effects were generally consistent with the sensitivity and subgroup analyses. In conclusion, our meta-analysis suggested that there was a significant association between CP and the risk of ED. Further epidemiological studies are needed to better estimate the key risk factors for periodontitis and their interaction effects.

Vasectomy and risk of prostate cancer: a systematic review and meta-analysis of cohort studies.

The results of published literature focusing on the association between vasectomy and the incidence of prostate cancer are often inconsistent. We conducted a meta-analysis to provide a quantitative assessment of the association between vasectomy and the risk of prostate cancer. We identified all cohort studies by searching the PubMed, Embase, and Cochrane Library before August 2014. The quality of the studies was evaluated using the Newcastle-Ottawa Scale checklist. Summary effect estimates with 95% confidence intervals (CI) were derived using a fixed or random effects model, depending on the heterogeneity of the included studies. Nine cohort studies that spanned across two continents involving 1 127 096 participants (ages 20-75) with 7539 cases of prostate cancer cases were included in the meta-analysis. The overall combined relative risks for men with the reference group were 1.08 (95% CI: 0.87-1.34) in a random effects, however, the association was not statistically significant (p = 0.48). Estimates of total effects were generally consistent in the sensitivity and subgroup analyses. No evidence of publication bias was observed. This meta-analysis indicated that vasectomy may not contribute to the risk of prostate cancer. The conclusion might have a far-reaching significance for the public health, especially in countries with high prevalence rates of vasectomy.