The Analysis of Biomimetic Caudal Fin Propulsion Mechanism with CFD

In nature, fish not only have extraordinary ability of underwater movement but also have high mobility and flexibility. The low energy consumption and high efficiency of fish propulsive method provide a new idea for the research of bionic underwater robot and bionic propulsive technology. In this paper, the swordfish was taken as the research object, and the mechanism of the caudal fin propulsion was preliminarily explored by analyzing the flow field structure generated by the swing of caudal fin. Subsequently, the influence of the phase difference of the heaving and pitching movement, the swing amplitude of caudal fin, and Strouhal number (St number) on the propulsion performance of fish was discussed. The results demonstrated that the fish can obtain a greater propulsion force by optimizing the motion parameters of the caudal fin in a certain range. Lastly, through the mathematical model analysis of the tail of the swordfish, the producing propulsive force principle of the caudal fin and the caudal peduncle was obtained. Hence, the proposed method provided a theoretical basis for the design of a high-efficiency bionic propulsion system.

Mechanisms influencing the efficiency of aquatic locomotion

The optimal aquatic locomotion has previously been associated with a narrow St(= fA/u) number range of 0.2–0.4. We present how animals tune their Strouhal (St) number to this range to reveal the mechanisms influencing efficiency. The self-propelled swimming of a 2D swimmer is simulated using an immersed boundary method. The locomotion kinematics is controlled by two variables, [Formula: see text] and frequency f. We show that only when animals constrain their [Formula: see text] = 0.125–0.25, their St number can fall into the optimal St range. When [Formula: see text] Hz, the St number is independent with frequency. Although different combinations of f and [Formula: see text] can achieve a same cruising velocity, high-f and low-[Formula: see text] motions are more efficient. This can be linked to its larger lateral velocity component in the proto-vortex region and the transition of the tail vortices into small eddies.

Second Malignancy Risk in Patients with Bronchopulmonary Carcinoids: Epidemiological Results from Italian Network of Cancer Registries

Purpose This epidemiological study aimed to determine the prevalence and characteristics of second tumors (STs) in patients with bronchopulmonary carcinoids (BCs). Methods Data on neuroendocrine carcinomas (NECs) from the AIRTUM registry (1975-2011) were used for the analysis. Among 32,325 NECs, we focused our analysis on 3,205 patients (9.9%) affected by BCs. The overall ST number and incidence were calculated. The number of STs was compared with the expected cancer number in the healthy Italian population, and the standardized incidence ratio (SIR) and 95% confidence intervals were calculated. Results The male/female ratio was 1.5:1 and the mean age 61.7 years (range: 7-94). A total of 640 STs were observed (overall incidence: 20%): 198 tumors were metachronous, 23 synchronous, and 419 occurred before the diagnosis of BC. The most common STs were bladder tumors (12.2%) followed by breast tumors (11.1%). We observed a large number of thyroid tumors (SIR = 3.88), with a remarkably higher frequency of thyroid tumors being synchronously detected with BC in female patients (SIR = 61.39). In male patients there was an increased frequency of urinary system tumors, in particular metachronous tumors of the kidney and renal pelvis (SIR = 3.34) and synchronous tumors of the urinary bladder (SIR = 11.48). Conclusions A high frequency of STs is predictable in patients with BCs, with synchronous thyroid tumors being observed in women and kidney and urinary bladder tumors in men. However, these data should be interpreted with caution, considering that the diagnosis of such tumors often occurs as an incidental finding during investigations for other malignancies.

Do patients with better neuro-cognition have better theory of mind?

IntroductionTheory of mind (ToM) has repeatedly been shown to be compromised in many patients with schizophrenia (SCZ). By contrast, the association between ToM deficits and neuro-cognitive functioning (NF) remains uncertain.ObjectivesTo investigate the association between ToM functioning and neuro-cognitive functioning in SCZ.MethodsFifty-eight outpatients with stable SCZ completed the intention-inferencing task (IIT), in which the ability to infer a character's intentions from 28 short comic strip stories is assessed. They also completed a neuro-cognitive battery comprising the following tests: the Hopkins Verbal Learning Test–Revised (HVLT-R), the Letter Digit Substitution Test (LDST), the Stroop Test (ST), the “Double Barrage” of Zazzo (DBZ), the Modified Card Sorting Test (MCST), Verbal Fluency (VF), the Trail Making Test-Part A (TMT-A) and the Digit Span (DS).ResultsThe performance in the IIT significantly correlated with performance in some neuro-cognitive tests including efficiency in DBZ, number of uncorrected mistakes in ST, number of correct categories in MCST and the time needed to succeed the TMT-A. No correlations were found between performance in the ITT and in memory tasks (HVLT-R and DS).ConclusionsToM may rely on some neuro-cognitive functions (mainly attention and executive functioning). Elucidating the exact relationship between ToM and NF may be useful as both are targeted in specific psychotherapeutic interventions.Disclosure of interestThe authors have not supplied their declaration of competing interest.

Asymptotic results for silent elimination

International audience Following the model of Bondesson, Nilsson, and Wikstrand, we consider randomly filled urns, where the probability of falling into urn i is the geometric probability (1-q)qi-1. Assuming n independent random entries, and a fixed parameter k, the interest is in the following parameters: Let T be the smallest index, such that urn T is non-empty, but the following k are empty, then: XT= number of balls in urn T, ST= number of balls in urns with index larger than T, and finally T itself..

Influence of weight bearing on the adaptations of rat plantaris to ablation of its synergists

The present study was designed to determine the contribution of weight bearing to the adaptations of the plantaris (PL) to synergist removal. PL from female rats were exposed to 28 days of a simultaneous condition of synergist ablation and hindlimb suspension. At 28 days, contractile responses and morphological measures were obtained and compared with muscles that either had synergists intact or were weight bearing or a combination of both. Synergist ablation prolonged PL maximum isometric twitch tension (Pt), time to peak tension (12%), and one-half relaxation time (12%); increased Pt (26%), maximum isometric tetanic tension (Po, 44%), fatigue resistance (FI, 42%), and fast fiber cross-sectional area (FT CSA, 20%); and decreased Pt/Po (13%) over nonablation counterparts. Suspension decreased PL Pt (26%), Po (26%), rest length (16%), FT CSA (31%), and slow-twitch fiber (ST) number (24%) but increased FI (75%) over weight-bearing counterparts. PL from weight-bearing animals were heavier than from suspended animals, and the extent of this response was greatest after synergist removal. Whole muscle and ST CSA and ST area contribution were greater only in weight-bearing synergist ablation muscles. Daily weight bearing (4 h) in synergist ablation hindlimb suspension groups caused PL weights and ST expressions to be halfway between 24-h suspension and 24-h weight-bearing groups. Our results suggest that weight bearing is not essential to the induction of several adaptations associated with synergist ablation but is required to cause the large muscle mass and ST expression characteristic of this model.