A Reanalysis of the Two Swimmers Problem, as Frequent Model of Michelson’s Interferometric Experiment Demonstrating that Transversal Path Is Not an Isosceles but a Right Triangle and the Race Will End in a Tie

The article initially reviews various works describing the physical model (PM) of Michelson’s interferometric experiment (ME), represented by the race between two swimmers Sw1, Sw2 (or boats, or planes, or sound signals, etc.). The two swimmers must each swim the same distance, but Sw1 will swim along the river flow, and Sw2 will swim perpendicularly to this direction. In all such works, it is considered that Sw2’s path will require less time and that it will reach the start point first. However, in this work, it has been determined that in order to make this possible, Sw2 must not observe the orthogonality rule of his start direction. This action would be deceitful to the arbiters and thus considered as non-fair-play towards Sw1. The article proves by swimming times calculus, that if the fair-play rules are observed, then the correct crosswise path (in water reference frame) is a right triangle instead of the isosceles triangle considered by Michelson. Consequently, the two times shall be perfectly equal and the race ends in a tie, and the myth of Sw2 as the race winner shall be debunked. Note that the same result shall also be applicable to Michelson’s interferometric experiment (ME) as well as to any similar experiment. Therefore, utilising the isosceles triangle as the transversal path in PM and also in ME is an erroneous act.

Prospects for Chinese Swimmers at the Atlanta Olympics

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World Class Elite Breaststrokers Downward Kick EMG Muscle Activity of the Gluteus Maximus, Quadriceps Femoris, Hamstring, Gastrocnemius Medialis, Rectus Abdominal, and Erector Spinae

This study analyzed the difference between using a downward breaststroke kick and a horizontal breaststroke kick in a sample of world class elite swimmers.We compared average muscle activity of the gluteus maximus,quadriceps femoris(vastus medialis and rectus femoris),hamstring/long head of the biceps femoris,gastrocnemius medialis,rectus abdominal,and erector spinae when using the downward breaststroke kick technique.We find that when this sample of swimmers utilized the downward breaststroke kick,max speed and velocity per stroke increased,measured by 12,788 EMG samples,where the results are highly correlated to duration of the aerodynamic buoyant force in breaststroke kick technique.The increases in performance observed from measuring the world class elite swimmers is highly correlated to the duration of the kick aerodynamic buoyant force.Among this sample of elite swimmers,the longer a swimmer demonstrates a buoyant force breaststroke kick,the lower the time in a 100 breaststroke.

The Influence of Swimming Athletes’ Burnout on Their Sports Participation Motivation in Hunan, China

Objective:This study aims to explore the effect of swimming athletes’burnout on their sports motivation in Hunan University,China.It seeks to understand how burnout influences various motivational factors,providing insights for optimizing swimming sports courses and enhancing student participation.Method:Employing random sampling,the study surveyed 260 swimming athletes from Hunan University.The research utilized a questionnaire divided into three parts:demographic information,the Athlete Burnout Questionnaire(ABQ),and the Intrinsic Motivation Inventory(IMI).Pearson’s r correlation analysis was conducted using SPSS to examine the relationships between burnout dimensions and motivational factors.Results:The study found significant correlations between a reduced sense of accomplishment and various motivational dimensions,including“interest/enjoyment,”“perceived competence,”“perceived choice,”and particularly“perceived tension.”Physical exhaustion showed a significant correlation only with“perceived tension,”indicating a strong link between psychological stress and physical fatigue.Sports devaluation was significantly correlated with“perceived tension,”suggesting that psychological stress impacts athletes’valuation of their sport.Conclusion:The findings highlight the complex interplay between burnout and motivation in swimming athletes.Psychological stress,as indicated by“perceived tension,”emerges as a key factor influencing both the physical and emotional aspects of burnout.The study underscores the need for holistic training approaches that balance physical training with psychological well-being,personalized coaching,and supportive environments to enhance intrinsic motivation and manage stress effectively.

抗生素作用下奇异变形菌生存方式的体内、体外实验研究

目的 观察在抗生素作用下 ,奇异变形菌 (Proteusmirabilis,PM)的体内、体外生存方式 ,并对其形成机制进行探讨。方法 通过观察PM在不同抗生素浓度区域中存在形式 ,测定最低抑菌浓度(MIC)、β 内酰胺酶活性、外膜通透性 ,观察上尿路PM感染动物模型尿液细菌涂片及肾脏病理切片 ,探讨PM在抗生素作用下的生存方式及其机制。结果 体外实验显示 ,PM在高抗生素浓度区域主要以swarmer细胞的形式存在 ,在低抗生素浓度区域则以swimmer细胞形式存在 ;多种抗生素对swarmer细胞MIC值显著高于swimmer细胞 (P <0 .0 5) ;Swarmer细胞与swimmer细胞间 β 内酰胺酶活性无显著差异 (P >0 .0 5) ;Swarmer细胞外膜对抗菌药物的通透率显著低于swimmer细胞 ;体内实验显示 ,应用了抗生素的大鼠上尿路感染模型 ,其尿液及肾脏病理切片中查见的细菌均为swarmer细胞。结论 Swarmer细胞是PM在逆境中一种重要的生存方式 ,外膜通透性降低是PMswarmer细胞耐药程度提高的主要原因 ,在PM感染的诊断和治疗过程中 ,可以考虑把swarmer细胞的检出与否及swarmer细胞耐药性检验作为诊断、制定治疗策略和判断预后的指标之一。

Validation of VO_2Peakand performance using a SciFit^TMArm Ergometer

For individuals with lower extremity injury or disability, upper body exercise provides a mechanism of functional mobility training, car-diovascular fitness, as well as a means for clinical fitness assessment. However, the validity of fitness assessment relies on the efficacy of di-agnostic tools and measures in order to provide meaningful data to clinicians. The purpose of this investigation was to determine if the SciFitTMPro II Arm Ergometer, a widely available upper body ergometer (UBE), is a reliable device for the determination of VO2Peak in fit able-bodied swimmers. Eight trained male swimmers (28 ± 9 yrs) performed two incremental protocols VO2Peak consisting of a 4-min warm-up at 15 W followed by 2 min at 50 W and progressing 10 W every 2 min until volitional exhaustion. There was a linear relationship between workload and VO2 in all trials (R = 0.96;p ≤ 0.01) while Cronbach’s alpha for test-retest reliability for VO2 was 0.98. In conclusion, the UBE is an accurate and reliable device for determination of VO2Peak in trained swimmers, and further may be a viable alternative trainingVO2Peak injured athlete.

Salivary Cortisol in an Extreme Non-Competitive Sport Exercise:Winter Swimming

Salivary cortisol role in response to strong stressors implied in extreme exercises and in sport practice was investigated with the aim to verify the claimed benefits that steers winter swimmers to self-prescribe the trials. Specific biochemical data allow to study a variety of stressors in sports and physical exercises, including extreme ones as winter swimming. Salivary cortisol behavior was examined in winter swimmers trials and canoe, canoe-polo competitions and comparisons of results between days with and without performances were reported. Cortisol circadian rhythm in sedentary subjects was collected as control. All the subjects were selected after anamnestic-clinical checks to evaluate their physiological conditions. The circadian cortisol behavior was reported in days with competitions and trials as well as between these events. Abrupt cortisol concentration changes were detected at the time of the trials and competitions: surprisingly, large increasing and decreasing concentrations were detected in both groups. Moreover, in winter swimmers, cortisol concentration remained fairly elevated in the evening of the trial days. In days without competitions, the usual cortisol circadian rhythm was recovered in sportsmen whereas cortisol concentrations persisted at high levels up to the evening in winter swimmers. The view that an extreme sport-like exercise as the winter swimming may well pose some treats ranging from subclinical aspects up to dismetabolic pathologies and even cardiovascular risks is strengthened by results of cortisol trends, suggesting to check physiological conditions. Results demonstrate that well-being feeling can be in contrast to the claimed improvements of health.

Objective response rate assessment in oncology: Current situation and future expectations

The tumor objective response rate(ORR)is an important parameter to demonstrate the efficacy of a treatment in oncology.The ORR is valuable for clinical decision making in routine practice and a significant end-point for reporting the results of clinical trials.World Health Organization and Response Evaluation Criteria in Solid Tumors(RECIST)are anatomic response criteria developed mainly for cytotoxic chemotherapy.These criteria are based on the visual assessment of tumor size in morphological images provided by computed tomography(CT)or magnetic resonance imaging.Anatomic response criteria may not be optimal for biologic agents,some disease sites,and some regional therapies.Consequently,modifications of RECIST,Choi criteria and Morphologic response criteria were developed based on the concept of the evaluation of viable tumors.Despite its limitations,RECIST v1.1 is validated in prospective studies,is widely accepted by regulatory agencies and has recently shown good performance for targeted cancer agents.Finally,some alternatives of RECIST were developed as immune-specific response criteria for checkpoint inhibitors.Immune RECIST criteria are based essentially on defining true progressive disease after a confirmatory imaging.Some graphical methods may be useful to show longitudinal change in the tumor burden over time.Tumor tissue is a tridimensional heterogenous mass,and tumor shrinkage is not always symmetrical;thus,metabolic response assessments using positron emission tomography(PET)or PET/CT may reflect the viability of cancer cells or functional changes evolving after anticancer treatments.The metabolic response can show the benefit of a treatment earlier than anatomic shrinkage,possibly preventing delays in drug approval.Computer-assisted automated volumetric assessments,quantitative multimodality imaging in radiology,new tracers in nuclear medicine and finally artificial intelligence have great potential in future evaluations.

Swimmer simulation using robot manipulator dynamics under steady water

To help swimmers improve, we have developed a computational swimming model using underwater manipulator dynamics. We formulate the equations of the underwater manipulator dynamics using the fluid drag, which is proportional to the square of the velocity. We construct a swimming model consisting of several links based on these equations. The distance traveled by the optimal swimming motion is derived using the model. The input parameters are the joint torques. The arm and leg positions in the model are determined from the joint torques. The force transmitted from the water to the manipulator is defined to be the action force, and the force transmitted from the manipulator to the water is defined to be the reaction force. This reaction force is defined to be the propulsion force. By combining the propulsion force generated by the arms and legs and the frictional drag with respect to the body we can calculate the distance traveled. To optimize the propulsion, which depends on the swimmer’s motion, a variational approach using the Lagrange function is applied. We can use the model to simulate 2D pseudo-backstroke motion. Our model has a lower cost than other techniques in the literature, because it does not require computational fluid dynamics (CFD). The swimmer velocity calculated by our model agrees quite closely with the results in the literature. The model qualitatively captures the movement of an actual swimmer.

Heavy metal stress induced hyperglycemia in blue swimmer crab, Portunus pelagicus

The study was to find out the effect of cadmium and mercury on levels of hemolymph glucose, crustacean hyperglycemic hormone（CHH） and hepatopancreas glycogen in the blue swimmer crab Portunus pelagicus. The experiments were performed in both intact and eyestalk ablated crabs. Quantification of CHH was done by the indirect ELISA with the aid of primary anti-Carcinus maenas-CHH antibody. Higher glucose concentration was observed on exposure to 8×10^–6 of cadmium（（825.6±5.42） μg/m L） and 6×10^–6 of mercury（（90.5±6.25） μg/m L）after 48 h and 24 h respectively. Higher level of hemolymph glucose was observed in eyestalk intact crabs on exposure to cadmium and mercury than eyestalk ablated crabs. Decrease in the levels of CHH was observed in both eyestalk intact and ablated crabs on heavy metal exposure. Decline of the hepatopancreas glycogen level was also witnessed with the exposure to heavy metal, which validated its utilization in the production of glucose. Thus this study brings to light, the variations in hemolymph glucose, CHH and hepatopancreas glycogen on heavy metal stress. These carbohydrate metabolites can be used as biomarkers in assessing heavy metal contamination in water bodies.

The Escaping and Returning of“The Swimmer”from the Symbolic Point of View

"The Swimmer"is the representative of John Cheever and it is one of the most famous short stories in present America.The story is simple and it is not long, but it has profound meaning because many imageries are been used in the story. It tries to analyze the escaping and returning from the symbolic point of view, for escaping is an important motif in modern society and in the end, only returning can realize self-redemption.

Swimmer with submerged SiO_(2)/Al/LiNbO_(3) surface acoustic wave propulsion system

Acoustic propulsion system presents a novel underwater propulsion approach in small scale swimmer.This study introduces a submerged surface acoustic wave(SAW)propulsion system based on the SiO_(2)/Al/LiNbO_(3) structure.At 19.25 MHz,the SAW propulsion system is proposed and investigated by the propulsion force calculation,PIV measurements and propulsion measurements.3.3 mN propulsion force is measured at 27.6 V_(pp).To evaluate the miniature swimmer,the SAW propulsion systems with multiple frequencies are studied.At 2.2 W,the submerged SAW propulsion system at 38.45 MHz demonstrates 0.83 mN/mm^(2) propulsion characteristics.At 96.13 MHz and 24 V_(pp),the movements of miniature swimmer with a fully submerged SAW propulsion system are recorded and analyzed to a maximum of 177 mm/s.Because of miniaturization,high power density,and simple structure,the SAW propulsion system can be expected for some microrobot applications,such as underwater drone,pipelinerobotand intravascularrobot.

The energy-saving advantages of burst-and-glide mode for thunniform swimming

This paper explores the energy-saving advantages of the burst-and-glide swimming and compares it with the normal self-swimming for a thunniform swimmer. The virtual swimmer allows us to perform controlled numerical experiments by varying the swinging tail number and the duty cycle while keeping the other parameters fixed. 3-D Navier-Stokes equations are used to compute the viscous flow over the swimmer. The user-defined functions and the dynamic mesh technology are used to simulate the burst-and-glide swimming. The results show that with the increase of the swinging tail number or the duty cycle, the swimming velocity, the power and the efficiency all increase, but the velocity-power ratio decreases somewhat. Therefore, choosing smaller swinging tail number and duty cycle is beneficial in reducing the power and increasing the velocity-power ratio, and thus to obtain the same velocity, less power is consumed. And to swim the same distance, the energy can significantly be saved. The power consumption, the efficiency and the velocity-power ratio in the burst-and-glide case are 43.9%, 40.6% and 1.15 times of those in the normal swimming case, respectively. The flow structures clearly show the evolution process around the fish in the burst-and-glide swimming. The findings can be used to reasonably plan the swimming action and to take the advantage of the external flow field energy for the fishlike robot, to be more efficient and energy-saving.

Purcell's Swimmer Revisited

Purcell’s swimmer was proposed by E. M. Purcell to explain bacterial swimming motions. It has been proved experimentally that a swimmer of this kind is possible under inertial-less and high viscous environment. But we could not investigate all the aspects of this mechanism through experiments due to practical difficulties. The computational fluid dynamics (CFD) provides complementary methods to experimental fluid dynamics. In particular, these methods offer the means of testing theoretical advances for conditions unavailable experimentally. Using such methodology, we have investigated the fluid dynamics of force production associated with the Purcell’s swimmer. By employing dynamic mesh and user-defined functions, we have computed the transient flow around the swimmer for various stroke angles. Our simulations capture the bidirectional swimming property successfully and are in agreement with existing theoretical and experimental results. To our knowledge, this is the first CFD study which shows the fact that swimming direction depends on stroke angle. We also prove that for small flapping frequencies, swimming direction can also be altered by changing frequency-showing breakdown of Stokes law with inertia.