Biological motion stimuli are attractive to medaka fish.

In many social fish species, visual cues play an important role in inducing shoaling behaviour. The present study is the first to examine whether and how "biological motion" depicting a moving creature by means of only a small number of isolated points induces shoaling behaviour in fish. Medaka (Oryzias latipes) were used because they are known to have high visual acuity and exhibit a strong tendency to form shoals. In experiment 1, we found that the presentation of medaka biological motion resulted in heightened shoaling behaviour when compared with that of non-biological motion (depicted by a small number of points placed at fixed distances that moved at a constant speed in a constant direction). In experiment 2, it was indicated that medaka biological motion was more effective at inducing shoaling behaviour when compared with human biological motion. In experiment 3, it was demonstrated that shoaling behaviour was largely dependent on the smoothness of the biological motion. In experiment 4, we revealed that shoaling behaviour was maximised in normal speed group and decreased in faster- and slower-than-normal speed groups. In experiment 5, it was shown that shoaling behaviour was slightly reduced when a reversed movie was presented. These results suggest that motion information extracted from conspecifics was sufficient to induce shoaling behaviour in medaka and that deviation from normal and familiar motion impeded shoaling behaviour. The naturalness of motion may be responsible for the induction of shoaling behaviour.

NMR Studies of Thermo-responsive Behavior of an Amphiphilic Poly(asparagine) Derivative in Water.

The thermo-responsive behavior of a unique biocompatible polymer, poly(N-substituted α/ß-asparagine) derivative (PAD), has been studied with several NMR methods. The 1H and 13C solution NMR measurements of the PAD in DMSO-d6 were used to investigate the isolated polymer and perform spectral assignments. By systematic addition of D2O we have tracked structural changes due to aggregation and observed contraction of hydrophilic side chains. Solution and cross polarization / magic angle spinning (CP/MAS) 13C NMR approaches were implemented to investigate the aggregates of the PAD aqueous solution during the liquid to gel transition as the temperature was increased. At temperatures near 20 °C, all of the peaks from the PAD were observed in the 13C CP/MAS and 13C solution NMR spectra, indicating the presence of polymer chain nodes. Increasing the temperature to 40 °C resulted in a partial disentanglement of the nodes due to thermal agitation and further heating resulted in little to no additional structural changes. Deuterium T1-T2 and T2-T2 two-dimensional relaxation spectroscopies using an inverse Laplace transform, were also implemented to monitor the water-PAD interaction during the phase transition. At temperatures near 20 °C the dynamical characteristics of water were manifested into one peak in the deuterium T1-T2 map. Increasing the temperature to 40 °C resulted in several distinguishable reservoirs of water with different dynamical characteristics. The observation of several reservoirs of water at the temperature of gel formation at 40 °C is consistent with a physical picture of a gel involving a network of interconnected polymer chains trapping a fluid. Further increase in temperature to 70 °C resulted in two non-exchanging water reservoirs probed by deuterium T2-T2 measurements.

Multi-scale dynamics by adjusting the leaking rate to enhance the performance of deep echo state networks.

Introduction: The deep echo state network (Deep-ESN) architecture, which comprises a multi-layered reservoir layer, exhibits superior performance compared to conventional echo state networks (ESNs) owing to the divergent layer-specific time-scale responses in the Deep-ESN. Although researchers have attempted to use experimental trial-and-error grid searches and Bayesian optimization methods to adjust the hyperparameters, suitable guidelines for setting hyperparameters to adjust the time scale of the dynamics in each layer from the perspective of dynamical characteristics have not been established. In this context, we hypothesized that evaluating the dependence of the multi-time-scale dynamical response on the leaking rate as a typical hyperparameter of the time scale in each neuron would help to achieve a guideline for optimizing the hyperparameters of the Deep-ESN. Method: First, we set several leaking rates for each layer of the Deep-ESN and performed multi-scale entropy (MSCE) analysis to analyze the impact of the leaking rate on the dynamics in each layer. Second, we performed layer-by-layer cross-correlation analysis between adjacent layers to elucidate the structural mechanisms to enhance the performance. Results: As a result, an optimum task-specific leaking rate value for producing layer-specific multi-time-scale responses and a queue structure with layer-to-layer signal transmission delays for retaining past applied input enhance the Deep-ESN prediction performance. Discussion: These findings can help to establish ideal design guidelines for setting the hyperparameters of Deep-ESNs.

Does Arctic sea ice reduction foster shelf-basin exchange?

The recent shift in Arctic ice conditions from prevailing multi-year ice to first-year ice will presumably intensify fall-winter sea ice freezing and the associated salt flux to the underlying water column. Here, we conduct a dual modeling study whose results suggest that the predicted catastrophic consequences for the global thermohaline circulation (THC), as a result of the disappearance of Arctic sea ice, may not necessarily occur. In a warmer climate, the substantial fraction of dense water feeding the Greenland-Scotland overflow may form on Arctic shelves and cascade to the deep basin, thus replenishing dense water, which currently forms through open ocean convection in the sub-Arctic seas. We have used a simplified model for estimating how increased ice production influences shelf-basin exchange associated with dense water cascading. We have carried out case studies in two regions of the Arctic Ocean where cascading was observed in the past. The baseline range of buoyancy-forcing derived from the columnar ice formation was calculated as part of a 30-year experiment of the pan-Arctic coupled ice-ocean general circulation model (GCM). The GCM results indicate that mechanical sea ice divergence associated with lateral advection accounts for a significant part of the interannual variations in sea ice thermal production in the coastal polynya regions. This forcing was then rectified by taking into account sub-grid processes and used in a regional model with analytically prescribed bottom topography and vertical stratification in order to examine specific cascading conditions in the Pacific and Atlantic sectors of the Arctic Ocean. Our results demonstrate that the consequences of enhanced ice formation depend on geographical location and shelf-basin bathymetry. In the Pacific sector, strong density stratification in slope waters impedes noticeable deepening of shelf-origin water, even for the strongest forcing applied. In the Atlantic sector, a 1.5x increase of salt flux leads to a threefold increase of shelf-slope volume flux below the warm core of Atlantic water. This threefold increase would be a sufficient substitute for a similar amount of dense water that currently forms in the Greenland, Iceland, and Norwegian (GIN) seas but is expected to decrease in a warming climate.

Integration of motion information in illusory motion perceived in stationary patterns.

Illusory motion is a phenomenon in which stationary images with repeating luminance gradient patterns appear to be moving. In this study, we conducted experiments focusing on illusory motion to verify the hypothetical rule that velocity information, extracted from local luminance patterns, is integrated by summation in visual information processing. This rule is based on the hypothesis of velocity integration, and could estimate perceived velocity of stimulus. The summation rule was evaluated by a psychophysical experiment. Our results showed that the summation rule unbiasedly predicted perceived velocity, suggesting that an algorithm for integrating velocity information in illusory motion is based on the summation rule. These results would contribute to understanding of the spatial integration of local motion signals in visual information processing.

The Characteristics of Badminton-Related Pain in Pre-Adolescent and Adolescent Badminton Players.

Body pain, often considered as an early sign of injury in young players, warrants thorough study. This study aimed to examine the distribution of badminton-related pain and prevalence in pre-adolescent and adolescent badminton players. Profiles of badminton-related pain were surveyed using a questionnaire among 366 pre-adolescent and adolescent badminton players aged 7-12 years. The distribution of badminton-related pain was described, and the pain incidence was calculated. Proportions of pain per 1000-training-hour exposures were the main outcome measures. The analysis considered various age groups (7-8, 9-10, and 11-12 years) and years of badminton experience (≤2, 2-3, and > 3 years). In total, 554 cases of badminton-related pain were reported. The ankle was the most common site, followed by knee, plantar, shoulder, and lower back. The overall pain rate per 1000-training-hour exposure was 3.06. The 11-12-year-old group showed the highest pain rate, significantly greater than the 7-8-year-old group and the 9-10-year-old group. Additionally, the prevalence of pain exhibited an increasing trend with age. Finally, regardless of the age groups, participants with 2-3 years of badminton experience had the highest pain rate. These findings might help inform targeted interventions to reduce the high prevalence of pain in various body regions across pre-adolescent and adolescent badminton players.

Horizontal distribution of surface microplastic concentrations and water-column microplastic inventories in the Chukchi Sea, western Arctic Ocean.

The recent influx of microplastics into the Arctic Ocean may increase environmental stress on the western Arctic marine ecosystem, which is experiencing significant sea-ice loss due to global warming. Quantitative data on microplastics in the western Arctic Ocean are very limited, and the microplastic budget of the water column is completely unknown. To fill in gaps in our knowledge of Arctic microplastics, we observed surface concentrations (number of particles per unit volume of seawater) of meso- and microplastics using a neuston net, and we observed wind speeds and significant wave heights in the Chukchi Sea, Bering Strait, and Bering Sea. From these observations, we estimated the total number (particle inventory) and mass (mass inventory) of microplastics in the entire water column by taking into account the effect of vertical mixing. The particle inventory of microplastics in the Chukchi Sea ranged from 0 to 18,815 pieces km-2 with a mean and standard deviation of 5236 ± 6127 pieces km-2. The mass inventory ranged from 0 to 445 g km-2 with a mean and standard deviation of 124 ± 145 g km-2. Mean particle inventories for the Chukchi Sea were one-thirtieth of those for the Arctic Ocean on the Atlantic side and less than one-tenth of the average for the global ocean, suggesting that the Chukchi Sea is less polluted. However, the annual flux of microplastics from the Pacific Ocean into the Chukchi Sea, estimated from microplastic concentrations in the Bering Strait, was about 5.5 times greater than the total amount of microplastic in the entire Chukchi Sea water. This suggests that microplastic inflows from the Pacific Ocean are accumulating in large amounts in reservoirs other than the Chukchi Sea water (e.g., sea ice and seafloor sediments) or in the downstream regions of the Pacific-origin water.

Atlantic-origin water extension into the Pacific Arctic induced an anomalous biogeochemical event.

The Arctic Ocean is facing dramatic environmental and ecosystem changes. In this context, an international multiship survey project was undertaken in 2020 to obtain current baseline data. During the survey, unusually low dissolved oxygen and acidified water were found in a high-seas fishable area of the western (Pacific-side) Arctic Ocean. Herein, we show that the Beaufort Gyre shrinks to the east of an ocean ridge and forms a front between the water within the gyre and the water from the eastern (Atlantic-side) Arctic. That phenomenon triggers a frontal northward flow along the ocean ridge. This flow likely transports the low oxygen and acidified water toward the high-seas fishable area; similar biogeochemical properties had previously been observed only on the shelf-slope north of the East Siberian Sea.

Evolutionary differentiation of androgen receptor is responsible for sexual characteristic development in a teleost fish.

Teleost fishes exhibit complex sexual characteristics in response to androgens, such as fin enlargement and courtship display. However, the molecular mechanisms underlying their evolutionary acquisition remain largely unknown. To address this question, we analyse medaka (Oryzias latipes) mutants deficient in teleost-specific androgen receptor ohnologs (ara and arb). We discovered that neither ar ohnolog was required for spermatogenesis, whilst they appear to be functionally redundant for the courtship display in males. However, both were required for reproductive success: ara for tooth enlargement and the reproductive behaviour eliciting female receptivity, arb for male-specific fin morphogenesis and sexual motivation. We further showed that differences between the two ar ohnologs in their transcription, cellular localisation of their encoded proteins, and their downstream genetic programmes could be responsible for the phenotypic diversity between the ara and arb mutants. These findings suggest that the ar ohnologs have diverged in two ways: first, through the loss of their roles in spermatogenesis and second, through gene duplication followed by functional differentiation that has likely resolved the pleiotropic roles derived from their ancestral gene. Thus, our results provide insights into how genome duplication impacts the massive diversification of sexual characteristics in the teleost lineage.

Origin of the ease of association of color names: Comparison between humans and AI.

Rapid evolution of artificial intelligence (AI) based on deep neural networks has resulted in artificial systems such as generative pre-trained transformer 3 (GPT-3), which can generate human-like language. Such a system may provide a novel platform for studying how human perception is related to knowledge and the ability of language generation. We compared the frequency distribution of basic color terms in the answers of human subjects and GPT-3 when both were asked similar questions regarding color names associated with the letters of the alphabet. We found that GPT-3 generated basic color terms at a frequency very similar to that of human non-synaesthetes. A similar frequency was observed when color names associated with numerals were tested indicating that simple co-occurrence of alphabet and color word in the trained dataset cannot explain the results. We suggest that the proposed experimental framework using the latest AI models has the potential to explore the mechanisms of human perception.

Influence of Ankle Injury on Subsequent Ankle, Knee, and Shoulder Injuries in Competitive Badminton Players Younger Than 13 Years.

Background: In recent years, there has been a trend in badminton toward more specialized training at an earlier age. Accompanying this trend is the increased frequency of injuries in young players. Ankle injury is the most common injury in pediatric sports; however, its influence on subsequent injuries is rarely considered. Purposes: To evaluate the incidence of ankle, knee, and shoulder injuries in youth badminton and to investigate the influence of ankle injuries on subsequent ankle, knee, and shoulder injuries. Study Design: Descriptive epidemiology study; Level of evidence, 3. Methods: A custom-designed questionnaire was used to survey Japanese players 7 to 12 years of age who attended national elementary school-level badminton tournaments between May and September 2019. Information including the players' characteristics, training history, injuries in the previous 12 months, and ankle injury histories were collected. Logistic regression was used for analysis. Results: A total of 478 players were included in the study, with 71 ankle injuries, 74 knee injuries, and 48 shoulder injuries reported. The injury incidence rates (per 1000 hours of play) were 0.23 (95% CI, 0.18-0.29) for the ankle, 0.24 (95% CI, 0.19-0.30) for the knee, and 0.16 (95% CI, 0.11-0.20) for the shoulder; 90.1% of ankle injuries, 25.7% of knee injuries, and 33.3% of shoulder injuries were acute. Previous ankle injury was significantly associated with subsequent ankle injury (adjusted Odds Ratio (OR), 3.05; 95% CI, 1.54-6.07; P < .05), knee injury (adjusted OR, 2.03; 95% CI, 1.12-3.69; P < .05), and shoulder injury (adjusted OR, 2.46; 95% CI, 1.26-4.83; P < .05). Conclusion: The study results indicated that previous injury to the ankle significantly increased the occurrence of subsequent ankle, knee, and shoulder injuries. Emphasizing protection and prevention of ankle injuries may help lower future injury risk in young badminton players.

Motion illusion-like patterns extracted from photo and art images using predictive deep neural networks.

In our previous study, we successfully reproduced the illusory motion perceived in the rotating snakes illusion using deep neural networks incorporating predictive coding theory. In the present study, we further examined the properties of the network using a set of 1500 images, including ordinary static images of paintings and photographs and images of various types of motion illusions. Results showed that the networks clearly classified a group of illusory images and others and reproduced illusory motions against various types of illusions similar to human perception. Notably, the networks occasionally detected anomalous motion vectors, even in ordinally static images where humans were unable to perceive any illusory motion. Additionally, illusion-like designs with repeating patterns were generated using areas where anomalous vectors were detected, and psychophysical experiments were conducted, in which illusory motion perception in the generated designs was detected. The observed inaccuracy of the networks will provide useful information for further understanding information processing associated with human vision.

Laterally biased diffusion of males of the water flea Daphnia magna.

The water flea, Daphnia magna, is a representative zooplankton that lives in freshwater environments. It primarily propagates via asexual reproduction in normal and healthy environmental conditions. Unsuitable environmental conditions induce D. magna to change its mode of reproduction from asexual to sexual reproduction. During sexual reproduction, D. magna produces special tough eggs (resting eggs) that can survive severe environmental conditions. Despite an increase in our understanding of their mating behavior, the sex-specific characteristics of swimming behavior among daphnid species are poorly understood. In this study, we analysed the swimming patterns and dynamics of female and male adult D. magna using computer modeling. Males displayed laterally biased diffusion in contrast to the homogeneous, nondirectional diffusion of females. Computer modeling analysis using a discrete-time Markov chain simulation, in which the frequencies of turning behavior were evaluated as probability distributions, explained the greater diffusion of males in the horizontal direction. We presumed that high diffusion in the horizontal direction would increase the probability of encountering a distant mate. Our findings suggest that male D. magna increases genotypic heterogeneity by effectively selecting certain motion parameters.

Massive transformation in FeNi nanopowders with nanotwin-assisted nitridation.

L10-ordered FeNi alloy (tetrataenite), a promising candidate for rare-earth-free and low-cost permanent magnet applications, is attracting increasing attention from academic and industrial communities. Highly ordered single-phase L10-FeNi is difficult to synthesis efficiently because of its low chemical order-disorder transition temperature (200-320 °C). A non-equilibrium synthetic route utilizing a nitrogen topotactic reaction has been considered a valid approach, although the phase transformation mechanism is currently unknown. Herein, we investigated the basis of this reaction, namely the formation mechanism of the tetragonal FeNiN precursor phase during the nitridation of FeNi nanopowders. Detailed microstructure analysis revealed that the FeNiN precursor phase could preferentially nucleate at the nanotwinned region during nitridation and subsequently grow following a massive transformation, with high-index irrational orientation relationships and ledgewise growth motion detected at the migrating phase interface. This is the first report of a massive phase transformation detected in an Fe-Ni-N system and provides new insights into the phase transformation during the nitriding process. This work is expected to promote the synthetic optimization of fully ordered FeNi alloys for various magnetic applications.

Glial Nax channels control lactate signaling to neurons for brain [Na+] sensing.

Sodium (Na) homeostasis is crucial for life, and Na levels in body fluids are constantly monitored in the brain. The subfornical organ (SFO) is the center of the sensing responsible for the control of salt-intake behavior, where Na(x) channels are expressed in specific glial cells as the Na-level sensor. Here, we show direct interaction between Na(x) channels and alpha subunits of Na(+)/K(+)-ATPase, which brings about Na-dependent activation of the metabolic state of the glial cells. The metabolic enhancement leading to extensive lactate production was observed in the SFO of wild-type mice, but not of the Na(x)-knockout mice. Furthermore, lactate, as well as Na, stimulated the activity of GABAergic neurons in the SFO. These results suggest that the information on a physiological increase of the Na level in body fluids sensed by Na(x) in glial cells is transmitted to neurons by lactate as a mediator to regulate neural activities of the SFO.

Epidemiology and pain in elementary school-aged players: a survey of Japanese badminton players participating in the national tournament.

Pain is common in athletes which should be well managed. To identify risk factors for shoulder pain, and the association between shoulder pain, lower back pain and knee pain among elementary school-aged badminton players, we conducted a cross-sectional study to collect data of the past year among 611 elementary school age (7-12 years old) badminton players belonging to the Japan Schoolchildren Badminton Federation using a questionnaire. Odds ratio (OR) and 95% confidence interval (CI) were estimated by multivariate logistic regression analysis. The overall incidence rate of shoulder injuries, lower back injuries and knee injuries was 0.38 injuries per 1000 h of badminton training. Players with training time per day > 2.5 h were 2.64 times (95% CI 1.03-6.78, p = 0.043) more likely to sustain shoulder pain than those with training time per day ≤ 2.5 h. A significant association was revealed between shoulder pain and knee pain as well as between lower back pain and knee pain as training hours per day > 2.5 h. Moreover, lower back pain was significantly associated with shoulder pain independent of training hours per day (≤ 2.5 h: p = 0.001; > 2.5 h: p < 0.001). These findings indicate that training time per day is risk factor, and shoulder pain, lower back pain and knee pain were associated with each other in elementary school-aged badminton players.

A new assignment technique of 2D-NMR spectra by spin-lock sequence to a tripeptide containing tryptophan in water.

We developed a new assignment technique of tryptophan residues using pulsed field gradient TOCSY-ROESY (PFG-TORO) and pulsed field gradient TOCSY-ROESY-TOCSY (PFG-TOROTO) techniques in water. Connectivity from betaH to zeta2H (H-7) via epsilon1H (H-1) and delta1H (H-2) in the TORO spectrum and from betaH to zeta3H (H-5) and eta2H (H-6) via epsilon1H (H-1) and delta1H (H-2) in the TOROTO spectrum could be able to assign each of the protons of the indole rings.

Increasing riverine heat influx triggers Arctic sea ice decline and oceanic and atmospheric warming.

Arctic river discharge increased over the last several decades, conveying heat and freshwater into the Arctic Ocean and likely affecting regional sea ice and the ocean heat budget. However, until now, there have been only limited assessments of riverine heat impacts. Here, we adopted a synthesis of a pan-Arctic sea ice-ocean model and a land surface model to quantify impacts of river heat on the Arctic sea ice and ocean heat budget. We show that river heat contributed up to 10% of the regional sea ice reduction over the Arctic shelves from 1980 to 2015. Particularly notable, this effect occurs as earlier sea ice breakup in late spring and early summer. The increasing ice-free area in the shelf seas results in a warmer ocean in summer, enhancing ocean-atmosphere energy exchange and atmospheric warming. Our findings suggest that a positive river heat-sea ice feedback nearly doubles the river heat effect.

Habitual physical activity and physical fitness in older Japanese adults: the Nakanojo Study.

BACKGROUND: Optimal patterns of habitual physical activity to ensure healthy aging remain unclear because of measurement limitations; most investigators have used either subjective questionnaires, or accelerometer or pedometer measurements limited to a single week, despite evidence of both the limited reliability/validity of questionnaires and seasonal changes in activity patterns. OBJECTIVE: This study explored possible associations between indicators of physical fitness (walking ability, upper- and lower-extremity isometric strength, and static and dynamic balance) and yearlong pedometer/accelerometer assessments of the quantity and quality of habitual physical activity in ostensibly healthy older adults. METHODS: Subjects were 76 male and 94 female Japanese aged 65-84 years. Each participant wore a pedometer/accelerometer for 1 year; measurements included the average number of steps taken each day and the duration of activity at an intensity of >3 metabolic equivalents (METs). Compliance was good, the instrument being removed for intervals of >3 h on <5% of days; data for such intervals were excluded from analysis. At the year's end, traditional laboratory techniques assessed preferred and maximal walking speeds, peak handgrip force, peak knee extension torque, total body sway, and maximal functional reach. RESULTS: After controlling data for age and/or sex, lower-extremity function (walking speeds and knee extension torque) showed significant positive relationships with the daily step count and daily duration of activity at >3 METs, especially in individuals > or = 75 years of age. On the other hand, handgrip force and body sway were unrelated to pedometer/accelerometer measurements. Linear and exponential regressions showed positive associations between walking speeds and pedometer/accelerometer scores up to the observed maxima of 13,700 steps/day and 62 min/day at >3 METs. However, when data were categorized into quartiles, walking speeds were not significantly greater in persons exceeding 7,000-8,000 steps/day and/or 15-20 min/day at >3 METs. With a few exceptions, subjects meeting these levels of habitual activity had walking speeds above the threshold predicting the development of functional dependence. CONCLUSION: The present data suggest that fitness is well maintained in elderly people who take >7,000-8,000 steps/day and/or spend >15-20 min/day at >3 METs. Nevertheless, the direction of this association merits exploration by longitudinal prospective studies and/or randomized controlled trials.

Year-long physical activity and metabolic syndrome in older Japanese adults: cross-sectional data from the Nakanojo Study.

BACKGROUND: We determined associations between habitual physical activity and metabolic syndrome in elderly persons. METHODS: Pedometer/accelerometers measured step count and activity intensity on a 24-hour basis in 220 free-living Japanese persons 65-84 years old throughout an entire year. At year end, participants were screened for metabolic syndrome (modified criteria of National Cholesterol Education Program Adult Treatment Panel III [NCEP-ATP III]). RESULTS: Most individuals 65-74 years old who took > 10,000 steps/d and/or spent > 30 min/d of activity > 3 metabolic equivalents (METs) had < or = 2 metabolic syndrome diagnostic markers, as did those 75-84 years old with > 8000 steps/d and/or > 20 min/d at > 3 METs. Multivariate-adjusted logistic regression analyses showed that the risk of metabolic syndrome was 4.3 (1.6-11.7) and 3.3 (1.3-8.8) times greater in the least active quartiles of participants (taking < 4700 steps/d and spending < 9 min/d at > 3 METs, respectively) relative to the most active quartiles (taking > 8500 steps/d and spending > 24 min/d at > 3 METs, respectively). CONCLUSIONS: The metabolic syndrome is less likely in elderly people taking > 8000-10,000 steps/d, and reaching an intensity > 3 METs for > 20-30 min/d, relative to their sedentary peers.