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The impact of Strouhal number St (= 0.1–1.0), Reynolds number Re (= 50–2000) and dimensionless wavelength λ (= 0.5–2.0) on the hydrodynamic performance of a travelling wavy foil of a constant length is extensively investigated. The relationship of time-mean thrust with St, Re and λ is presented, suggesting that the propulsive force increases with increasing St, Re and λ. As such, the drag–thrust boundary advances as these parameters increase. A shorter λ makes the thrust steadier while a longer λ enhances the maximum instantaneous thrust. The latter is beneficial for prey to escape from a predator. The fluid added mass caused by the foil oscillation increases with St and λ but declines with Re (<500). Seven types of wake structures produced by the foil are identified, discussed and connected to thrust generation, showing how St, Re and λ affect the fluid dynamics, wake transition, vortex strength, wake jet, velocity, added mass, added damping, power input, efficiency and pressure profiles. The outcome of this work renders a physical basis for understanding the swimming of aquatic animals.

Recent studies have shown that superimposing rhythmic perturbations to oscillating tailbeats could simultaneously enhance both the thrust and efficiency (Lehn et al., Phys. Rev. Fluids, vol. 2, 2017, p. 023101; Chao et al., PNAS Nexus, vol. 3, 2024, p. 073). However, these investigations were conducted with a tethered flapping foil, overlooking the self-propulsion intrinsic to real swimming fish. Here, we investigate how the high-frequency, low-amplitude superimposed rhythmic perturbations impact the self-propelled pitching and heaving swimming of a rigid foil. The swimming-speed-based Reynolds number ranges from 1400 to 2700 in our study, depending on superimposed perturbations and swimming modes. Numerical results reveal that perturbations significantly increase swimming speeds in both pitching and heaving motions, while enhancing efficiency exclusively in the heaving motion. Further derived scaling laws elucidate the relationships of perturbations with speeds, power costs and efficiency, respectively. These findings not only hypothesise the potential advantages of perturbations in biological systems, but also inspire designs and controls in biomimetic propulsion and manoeuvring within aquatic environments.

The hydrodynamics of a self-propelling swimmer undergoing intermittent S-start swimming are investigated extensively with varying duty cycle $DC$, swimming period $T$, and tailbeat amplitude $A$. We find that the steady time-averaged swimming speed $\\bar {U}_x$ increases directly with $A$, but varies inversely with $DC$ and $T$, where there is a maximal improvement of $541.29\\,\\%$ over continuous cruising swimming. Our results reveal two scaling laws, in the form of input versus output relations, that relate the swimmer's kinematics to its hydrodynamic performance: swimming speed and efficiency. A smaller $DC$ causes increased fluctuations in the swimmer's velocity generation. A larger $A$, on the other hand, allows the swimmer to reach steady swimming more quickly. Although we set out to determine scaling laws for intermittent S-start swimming, these scaling laws extend naturally to burst-and-coast and continuous modes of swimming. Additionally, we have identified, categorized and linked the wake structures produced by intermittent S-start swimmers with their velocity generation.

We performed this meta-analysis to evaluate the predictive value of different parameters in the sperm retrieval rate （SRR） of microdissection testicular sperm extraction （TESE） in patients with nonobstructive azoospermia （NOA）. All relevant studies were searched in PubMed, Web of Science, EMBASE, Cochrane Library, and EBSCO. We chose three parameters to perform the meta-analysis： follicle-stimulating hormone （FSH）, testicular volume, and testicular histopathological findings which included three patterns： hypospermatogenesis （HS）, maturation arrest （MA）, and Sertoli-cell-only syndrome （SCOS）. If there was a threshold effect, only the area under the summary receiver operating characteristic curve （AUSROC） was calculated. Otherwise, the pooled sensitivity, specificity, positive likelihood ratio （PLR）, negative likelihood ratio （NLR）, and the diagnostic odds ratio （DOR） were also calculated. Twenty-one articles were included in our study finally. There was a threshold effect among studies investigating FSH and SCOS. The AUSROCs of FSH, testicular volume, HS, MA, and SCOS were 0.6119, 0.6389, 0.6758, 0.5535, and 0.2763, respectively. The DORs of testicular volume, HS, and MA were 1.98, 16.49, and 1.26, respectively. The sensitivities of them were 0.80, 0.30, and 0.27, while the specificities of them were 0.35, 0.98, and 0.76, respectively. The PLRs of them were 1.49, 10.63, and 1.15, respectively. And NLRs were 0.73, 0.72, and 0.95, respectively. All the investigated factors in our study had limited predictive value. However, the histopathological findings were helpful to some extent. Most patients with HS could get sperm by microdissection TESE.

The artificial lateral line system, composed of velocity and pressure sensors, is the sensing system for fish-like robots by mimicking the lateral line system of aquatic organisms. However, accurately estimating the self-motion of the fish-like robot remains challenging due to the complex flow field generated by its movement. In this study, we employ the mode decomposition method to estimate the motion states based on artificial lateral lines for the fish-like robot. We find that primary decomposed modes are strongly correlated with the velocity components and can be interpreted through Lighthill’s theoretical pressure model. Moreover, our decomposition analysis indicates the redundancy of the sensor array design, which is verified by further synthetic analysis and explained by flow visualization. Finally, we demonstrate the generalizability of our method by accurately estimating the self-states of the fish-like robot under varying oscillation parameters, analyzing three-dimensional pressure data from the computational fluid dynamics simulations of boxfish ( Ostracion cubicus ) and eel-like ( Anguilla anguilla ) models, and robustly estimating the self-velocity in complex flows with vortices caused by a neighboring robot. Our interpretable and generalizable data-driven pipeline could be beneficial in generating hydrodynamic sensing hypotheses in biofluids and enhancing artificial-lateral-line-based perception in autonomous underwater robotics. Accurately estimating the self-motion of fish-like robots in complex environments remains a challenge for current sensing systems based on artificial lateral lines. Here, authors employ a mode decomposition method to estimate the motion states of the robot, enhancing the sensing capabilities of fish-like robotic systems.

Chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS), also known as National Institutes of Health (NIH) type III prostatitis, is a common disorder with an unclear etiology and no known curative treatments. Based on the presence or absence of leukocytes in expressed prostatic secretion (EPS), CP/CPPS is classified further into IIIa (inflammatory) and IIIb (noninflammatory) subtypes. However, the severity of symptoms is not entirely consistent with the white blood cell (WBC) count. Following the preliminary finding of a link between inflammatory cytokines and CP/CPPS, we performed this clinical study with the aim of identifying cytokines that are differentially expressed according to whether the prostatitis subtype is IIIa or IIIb. We found that granulocyte colony-stimulating factor (G-CSF), interleukin-18 (IL-18), and monocyte chemoattractant protein-1 (MCP-1) levels were significantly elevated and interferon-inducible protein-10 (IP-10) and platelet-derived growth factor-BB (PDGF-BB) levels were downregulated in the EPS of patients with type IIIa prostatitis. In a word, it is a meaningful study in which we investigate the levels of various cytokines in EPS according to whether prostatitis is the IIIa or IIIb subtype. The combination of G-CSF, IL-18, MCP-1, IP-10, and PDGF-BB expression levels could form a basis for classification, diagnosis, and therapeutic targets in clinical CP/CPPS.

Background This study aimed to compare the predictive value of two diagnostic criteria for bronchopulmonary dysplasia (BPD) in preterm infants with gestational age (GA) < 32 weeks for death or severe respiratory morbidity at corrected age of 18–24 months. Methods In this retrospective cohort study, clinical data from July 2019 to September 2021 were classified by 2018 National Institute of Child Health and Human Development (NICHD) and 2019 Jensen definitions of BPD. Based on the follow-up results, the enrolled population was divided into adverse outcome group and normal outcome group. Logistic regression and receiver operating characteristic (ROC) curve analyses were conducted to explore the risk factors of adverse outcomes and evaluate the predictive value of both diagnostic criteria. Results Of 451 infants, 141 (31.3%) had adverse outcomes, which increased with increasing severity of BPD. Logistic regression analysis showed only BPD was an independent risk factor for adverse outcomes in preterm infants. ROC analysis revealed that both diagnostic criteria showed similar predictive values (2018 NICHD definition AUC = 0.771 vs. 2019 Jensen definition AUC = 0.770), with specificities of 93.5% and 96.8%, respectively; however, combining them separately with GA or birth weight did not improve their predictive values. Conclusions The two novel definitions of BPD demonstrate similar predictive values in predicting death or severe respiratory morbidity at corrected age of 18–24 months, with higher specificity observed in both.

Pulsar wind nebula (PWN) Boomerang and the associated supernova remnant (SNR) G106.3+2.7 are among candidates for the ultra-high-energy (UHE) gamma-ray counterparts published by LHAASO. Although the centroid of the extended source, LHAASO J2226+6057, deviates from the pulsar’s position by about 0.3∘, the source partially covers the PWN. Therefore, we cannot totally exclude the possibility that part of the UHE emission comes from the PWN. Previous studies mainly focus on whether the SNR is a PeVatron, while neglecting the energetic PWN. Here, we explore the possibility of the Boomerang Nebula being a PeVatron candidate by studying its X-ray radiation. By modeling the diffusion of relativistic electrons injected in the PWN, we fit the radial profiles of X-ray surface brightness and photon index. The solution with a magnetic field B=140μG can well reproduce the observed profiles and implies a severe suppression of IC scattering of electrons. Hence, if future observations reveal part of the UHE emission originating from the PWN, we propose to introduce a proton component to account for the UHE emission in light of the recent LHAASO measurement on Crab Nebula. In this sense, Boomerang Nebula would be a hadronic PeVatron.

Abstract Understanding how animals swim efficiently and generate high thrust in complex fluid environments is of considerable interest to researchers in various fields, including biology, physics, and engineering. However, the influence of often-overlooked perturbations on swimming fish remains largely unexplored. Here, we investigate the propulsion generated by oscillating tailbeats with superimposed rhythmic perturbations of high frequency and low amplitude. We reveal, using a combination of experiments in a biomimetic fish-like robotic platform, computational fluid dynamics simulations, and theoretical analysis, that rhythmic perturbations can significantly increase both swimming efficiency and thrust production. The introduction of perturbations increases pressure-induced thrust, while reduced phase lag between body motion and the subsequent fluid dynamics response improves swimming efficiency. Moreover, our findings suggest that beneficial perturbations are sensitive to kinematic parameters, resolving previous conflicts regarding the effects of such perturbations. Our results highlight the potential benefits of introducing perturbations in propulsion generators, providing potential hypotheses for living systems and inspiring the design of artificial flapping-based propulsion systems.

To examine the bactericidal effects of three different states of medical ozone (liquid, gas, and oil) against drug-resistant strains of common bacteria on burn wounds, which could as a clinical reference. Three multidrug-resistant strains of methicillin-resistant , pan-resistant , and ESBLs were identified from burn wounds. The colonies of the three varieties of bacteria were each carried out using the pour plate method prior to the start of the experiment. Then, depending on the state of ozone, different treatment procedures are applied. Group of ozone gas: in a closed glass jar, the bacterial liquid was injected into a single layer of sterile gauze, and the ozone gas concentration was held at 50 g/mL. The bacterial liquid was diluted and combined directly with ozone water in the ozone water group. Ozone is a type of oil: after the emulsifier was added to the oil group. The gas, water, and oil groups were rapidly neutralized and counted again after 5, 10, and 30 minutes. Ozone gas and oil groups totally eliminated multidrug resistant bacteria in the above study within 30 minutes. (2) At 5 and 10 minutes, the difference in bactericidal effect between ozone gas group and ozone water and oil group was statistically significant (P<0.05), and there was no significant difference between ozone water and oil groups (P>0.05); at the time of 30 minutes, the effects of bactericidal effect between ozone water group and ozone gas and oil had no significance (P> 0.05). Ozone has the ability to kill bacteria, depending on the treatment time, different ozone types should be chosen for sterilization and disinfection in clinical application.