Numerical simulations are employed to study the hydrodynamics of self-propelled thunniform swimming. The swimmer is modeled as a tuna-like flexible body undulating with kinematics of thunniform type. The wake evolution follows the vortex structures arranged nearly vertical to the forward direction, vortex dipole formation resulting in the propulsion motion, and finally a reverse Kármán vortex street. We also carry out a systematic parametric study of various aspects of the fluid dynamics behind the freely swimming behavior, including the swimming speed, hydrodynamic forces, power requirement and wake vortices. The present results show that the fin thrust as well as swimming velocity is an increasing function of both tail undulating amplitude Ap and oscillating amplitude of the caudal fin θm. Whereas change on the propulsive performance with Ap is associated with the strength of wake vortices and the area of suction region on the fin, the swimming performance improves with θm due to the favorable tilting of the fin that make the pressure difference force more oriented toward the thrust direction. Moreover, the energy loss in the transverse direction and the power requirement increase with Ap but decrease with θm, and this indicates that for achieving a desired swimming speed increasing θm seems more efficiently than increasing Ap. Furthermore, we have compared the current simulations with the published experimental studies on undulatory swimming. Comparisons show that our work tackles the flow regime of natural thunniform swimmers and follows the principal scaling law of undulatory locomotion reported. Finally, this study enables a detailed quantitative analysis, which is difficult to obtain by experiments, of the force production of the thunniform mode as well as its connection to the self-propelled swimming kinematics and vortex wake structure. The current findings help provide insights into the swimming performance and mechanisms of self-propelled thunniform locomotion.

BackgroundCatgut implantation at acupoints has been used in China to treat allergic rhinitis (AR) for a long time. However, its efficacy and safety in the treatment of AR is controversial due to the poor quality of the clinical trial of this therapy. This study aims to identify whether catgut implantation at acupoints is indeed an effective and safe treatment for patients with persistent or intermittent allergic rhinitis (PER or IAR) by comparing with sham catgut implantation treatment.Methods and designThis study compares real versus sham catgut implantation at acupoints in 242 patients with a history of PER or IAR and with a positive skin prick test (SPT). The trial will be conducted in the Teaching Hospital of Chengdu University of Traditional Chinese Medicine. In the study, patients will be randomly assigned by computer-generated randomization list into two groups and assessed prior to treatment. Then, they will receive two sessions of treatments (once per 2 weeks) for 4 consecutive weeks and have a follow-up phase of 12 weeks. The administration of catgut implantation (or sham-control) at acupoints follows the guidelines for clinical research on acupuncture (WHO Regional Publication, Western Pacific Series No.15, 1995), and is performed double-blindly by a well-trained physician in acupuncture. The main outcome measures include the primary and secondary indicators. Primary indicators are subjective symptoms scores evaluated by visual analogue scales (VAS) and Rhinoconjunctivitis Quality of Life Questionnaires (RQLQ). The secondary indicators are the results of laboratory examinations, such as serum allergen-specific IgE, nasal inflammatory cells counts (mast cells, eosinophils, and T cells) and nitric oxide concentration in nasal excretion. The use of anti-allergic medication will also be recorded as one of the secondary indicators. Furthermore, adverse events will be recorded and analyzed. If any participants withdraw from the trial, intention-to-treat analysis (ITT) and per-protocol (PP) analysis will be performed.DiscussionThe important features of this trial include the randomization procedures, large sample, and a standardized protocol of catgut implantation at acupoints. This trial will be the first study with a high evidence level in China in order to assess the efficacy and safety of catgut implantation at acupoints in treatment of AR following a randomized, double-blind sham-controlled method.Trial registrationChinese Clinical Trial Registry: ChiCTR-TRC-12002191

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Based on the data of listed construction companies in the jewelry manufacturing industry in 1994 from 2014 to 2017, this article uses the generalized least squares method to analyze the relationship between green energy technology innovation, construction enterprises’ growth performance and R&D investment intensity, and explores the impact of green energy technology innovation on construction enterprises’ growth performance and analyzes the moderating effect of R&D investment intensity. The empirical results show that green energy technological innovation has a significant positive impact on construction enterprises’ growth performance. The intensity of R&D investment has a significant negative regulatory effect on the relationship between green energy technological innovation and construction enterprises’ growth performance.

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