A special class of random walks, so-called Lévy walks, has been observed in a variety of organisms ranging from cells, insects, fishes, and birds to mammals, including humans. Although their ...prevalence is considered to be a consequence of natural selection for higher search efficiency, some findings suggest that Lévy walks might also be epiphenomena that arise from interactions with the environment. Therefore, why they are common in biological movements remains an open question. Based on some evidence that Lévy walks are spontaneously generated in the brain and the fact that power-law distributions in Lévy walks can emerge at a critical point, we hypothesized that the advantages of Lévy walks might be enhanced by criticality. However, the functional advantages of Lévy walks are poorly understood. Here, we modeled nonlinear systems for the generation of locomotion and showed that Lévy walks emerging near a critical point had optimal dynamic ranges for coding information. This discovery suggested that Lévy walks could change movement trajectories based on the magnitude of environmental stimuli. We then showed that the high flexibility of Lévy walks enabled switching exploitation/exploration based on the nature of external cues. Finally, we analyzed the movement trajectories of freely moving Drosophila larvae and showed empirically that the Lévy walks may emerge near a critical point and have large dynamic range and high flexibility. Our results suggest that the commonly observed Lévy walks emerge near a critical point and could be explained on the basis of these functional advantages.
We conducted a systematic review and meta‐analysis of population‐based cohort studies of maternal body mass index (BMI) and risk of adverse birth and health outcomes in low‐ and middle‐income ...countries. PubMed, Embase, CINAHL and the British Nursing Index were searched from inception to February 2014. Forty‐two studies were included. Our study found that maternal underweight was significantly associated with higher risk of preterm birth (odds ratio OR, 1.13; 95% confidence interval CI, 1.01–1.27), low birthweight (OR, 1.66; 95% CI, 1.50–1.84) and small for gestational age (OR, 1.85; 95% CI, 1.69–2.02). Compared with mothers with normal BMI, overweight or obese mothers were at increased odds of gestational diabetes, pregnancy‐induced hypertension, pre‐eclampsia, caesarean delivery and post‐partum haemorrhage. The population‐attributable risk (PAR) indicated that if women were entirely unexposed to overweight or obesity during the pre‐pregnancy or early pregnancy period, 14% to 35% fewer women would develop gestational diabetes, pre‐eclampsia or pregnancy‐induced hypertension in Brazil, China, India, Iran or Thailand. The highest PAR of low birthweight attributable to maternal underweight was found in Iran (20%), followed by India (18%), Thailand (10%) and China (8%). Treatment and prevention of maternal underweight, overweight or obesity may help reduce the burden on maternal and child health in developing countries.
Language is a result of brain function; thus, impairment in cognitive function can result in language disorders. Understanding the aging of brain functions in terms of language processing is crucial ...for modern aging societies. Previous studies have shown that language characteristics, such as verbal fluency, are associated with cognitive functions. However, the scaling laws in language in elderly people remain poorly understood. In the current study, we recorded large-scale data of one million words from group conversations among healthy elderly people and analyzed the relationship between spoken language and cognitive functions in terms of scaling laws, namely, Zipf's law and Heaps' law. We found that word patterns followed these scaling laws irrespective of cognitive function, and that the variations in Heaps' exponents were associated with cognitive function. Moreover, variations in Heaps' exponents were associated with the ratio of new words taken from the other participants' speech. These results indicate that the exponents of scaling laws in language are related to cognitive processes.
Endoscopic submucosal dissection (ESD) has evolved into a viable treatment modality for superficial esophageal cancer. ESD offers a distinct advantage given the ability to perform en bloc resection ...enabling accurate histopathologic assessment. Data from published literature has established ESD as the preferred option in the treatment of superficial squamous cell carcinoma with complete resection rates of 78-100%, and a low rate recurrence of 0-2.6%. En bloc resection for esophageal SCC is curative for tumors with M1 (intrapethelial) or M2 (invasion into the lamina propria) involvement with no lymphovascular invasion. Tumors that contain lymphovascular invasion or submucosal invasion greater than 200 μm should be treated as advanced carcinomas due to the increased risk of lymph node metastasis. In contrast, the role of ESD in Barrett's esophagus is more limited due to the high rate of efficacy of EMR. A randomized control trial comparing EMR and ESD strategies found a higher R0 resection rate for ESD, but no significant difference in complete remission from neoplasia at 3 month follow up. Endoscopic ultrasound (EUS) has a limited role in the evaluation of superficial esophageal cancer. Alternatively, detailed endoscopic assessment along with magnification endoscopy or narrow band imaging, may provide greater utility than EUS. The most common adverse events of ESD in the esophagus include perforation and stricture. Perforation can often be managed by defect closure along with non-operative conservative management. Steroid administration with either topical or local injection can be effective management in stricture prevention. Continued refinement of ESD technique and innovation will overcome some of the current limitations of ESD and enable curative resection of superficial esophageal cancer as an alternative to invasive surgery.
We examined the friction and wear properties of nanostripe-inducing structures (NISs), namely, a multilayer film consisting of layers of a soft metal (Ag) and a hard metal (Cr) applied on a periodic ...slope array on a Si substrate. The friction coefficients of the different samples of the Cr-Ag NISs were measured by rubbing four different types of sliders against the samples using a reciprocating friction tester under dry conditions. The wear depths were examined using a confocal microscope. It was found that, when the rubbing was done under vacuum conditions of 2 × 10−4 Pa, the friction coefficient decreased with increasing number of oscillations, and its values ranged between 0.2 and 0.3 at the end of the test. In addition, the wear resistances of the different NIS samples were observed to be one order of magnitude higher than that of a single Cr layer on a periodic slope array.
•Nanostripe-Inducing Structures (NISs) realize self-repairing solid lubricating film.•The NISs generate an Ag transfer thin film on the Cr surface by rubbing.•The NISs reduced friction coefficient to 0.2–0.3, irrespective to the slider material and to its curvature radius.
Tracking animal movements such as walking is an essential task for understanding how and why animals move in an environment and respond to external stimuli. Different methods that implemented image ...analysis and a data logger such as GPS have been used in laboratory experiments and in field studies, respectively. Recently, animal movement patterns without stimuli have attracted an increasing attention in search for common innate characteristics underlying all of their movements. However, it is difficult to track the movements in a vast and homogeneous environment without stimuli because of space constraints in laboratories or environmental heterogeneity in the field, hindering our understanding of inherent movement patterns. Here, we applied an omnidirectional treadmill mechanism, or a servosphere, as a tool for tracking two-dimensional movements of small animals that can provide both a homogenous environment and a virtual infinite space for walking. To validate the use of our tracking system for assessment of the free-walking behavior, we compared walking patterns of individual pillbugs (Armadillidium vulgare) on the servosphere with that in two types of experimental flat arenas. Our results revealed that the walking patterns on the servosphere showed similar diffusive characteristics to those observed in the large arena simulating an open space, and we demonstrated that our mechanism provides more robust measurements of diffusive properties compared to a small arena with enclosure. Moreover, we showed that anomalous diffusion properties, including Lévy walk, can be detected from the free-walking behavior on our tracking system. Thus, our novel tracking system is useful to measure inherent movement patterns, which will contribute to the studies of movement ecology, ethology, and behavioral sciences.
•Word production patterns can be quantified using Heaps’ law.•The exponent β of Heaps’ law was estimated from conversational data.•β was positively correlated with the left anterior middle temporal ...gyrus volume.•β was negatively correlated with the rsFC between this region and the precuneus.•Different word usage was related to its structural and functional characteristics.
Vocabulary is based on semantic knowledge. The anterior temporal lobe (ATL) has been considered an essential region for processing semantic knowledge; nonetheless, the association between word production patterns and the structural and functional characteristics of the ATL remains unclear. To examine this, we analyzed over one million words from group conversations among community-dwelling older adults and their multimodal magnetic resonance imaging data. A quantitative index for the word production patterns, namely the exponent β of Heaps’ law, positively correlated with the left anterior middle temporal gyrus volume. Moreover, β negatively correlated with its resting-state functional connectivity with the precuneus. There was no significant correlation with the diffusion tensor imaging metrics in any fiber. These findings suggest that the vocabulary richness in spoken language depends on the brain status characterized by the semantic knowledge-related brain structure and its activation dissimilarity with the precuneus, a core region of the default mode network.
Summary Awake bruxism is defined as the awareness of jaw clenching. Its prevalence is reported to be 20% among the adult population. Awake bruxism is mainly associated with nervous tic and reactions ...to stress. The physiology and pathology of awake bruxism is unknown, although stress and anxiety are considered to be risk factors. During sleep, awareness of tooth grinding (as noted by sleep partner or family members) is reported by 8% of the population. Sleep bruxism is a behaviour that was recently classified as a ‘sleep‐related movement disorder’. There is limited evidence to support the role of occlusal factors in the aetiology of sleep bruxism. Recent publications suggest that sleep bruxism is secondary to sleep‐related micro‐arousals (defined by a rise in autonomic cardiac and respiratory activity that tends to be repeated 8–14 times per hour of sleep). The putative roles of hereditary (genetic) factors and of upper airway resistance in the genesis of rhythmic masticatory muscle activity and of sleep bruxism are under investigation. Moreover, rhythmic masticatory muscle activity in sleep bruxism peaks in the minutes before rapid eye movement sleep, which suggests that some mechanism related to sleep stage transitions exerts an influence on the motor neurons that facilitate the onset of sleep bruxism. Finally, it remains to be clarified when bruxism, as a behaviour found in an otherwise healthy population, becomes a disorder, i.e. associated with consequences (e.g. tooth damage, pain and social/marital conflict) requires intervention by a clinician.
In this study, characterization was conducted on resistant starch, isolated from different cultivars of V. unguiculata (Bechuana White, Fahari, PAN 311, TVU 11424 and DT 129-4). The fraction of ...resistant starch obtained was found in the range of 9.42–13.74%, with DT 129-4 yielding the highest fraction. Amylose content of the starches varied between 18.72 and 19.67%. Swelling power, solubility index and syneresis was directly proportional to the different temperatures. A correlation between amylose content and swelling power was observed as swelling power was indirectly proportional to amylose content. Water and oil absorption capacity was 31.93–88.06% and 10.29–27.71% respectively. Foaming, emulsion capacity, and stability were done, however, due to the lack of protein in the resistant starch samples, results obtained were relatively low, ranging between 0.00 and 22.41%. The degree of whiteness during colour analysis ranged between 80.81 and 84.61%. The FTIR-spectra displayed no distinctive difference amongst the vibration bands on the hydroxyl, methine and carbonyl frequency stretches and confirmed the polysaccharide nature of the resistant starch. The XRD spectra displayed a Ca-type crystalline structure for all 5 cultivars. Overall, this study shows that resistant starch has the potential to be used in many food applications and as a microencapsulation membrane.
•Vigna unguiculata cultivars contain approximately 9–14% resistant starch.•Swelling power of resistant starch is indirectly proportional to amylose content.•Resistant starch displayed a Ca-type crystalline structure.•Resistant starch has the potential to be used in various food applications.
One of the most important survival strategies of organisms is to avoid predators. Studying one of such strategies, namely, death‐feigning behavior, has recently become more common. The success or ...failure of this antipredator strategy will be affected by the circadian rhythms of both prey and predator because death feigning sometimes has a diurnal rhythm. However, few studies have analyzed the effects of differences in circadian rhythms on predator‐avoidance behavior at the genetic level. Recently, the relationship between genes relating to circadian rhythm and death‐feigning behavior, an antipredator behavior, has been established at the molecular level. Therefore, in this study, we compared three circadian rhythm‐related traits, the free‐running period of rhythms, amplitude of circadian rhythms, and total activity of strains of three Tribolium species that were artificially selected for the death‐feigning duration: short (S‐strains) and long (L‐strains) durations. As a result, the amplitude of circadian rhythms and total activity were significantly different between S‐ and L‐strains, but there was no difference in the free‐running periods of the rhythm between the strains in T. castaneum, T. confusum, and T. freemani. Although the relationship between death‐feigning behavior and activity has been reported for all three species, a genetic relationship between the duration of death feigning and the amplitude of circadian rhythms has been newly found in the present study. It is important to investigate the relationship between antipredator strategies and circadian rhythms at the molecular level in the future.
We compared three circadian rhythm‐related traits, the free‐running period of rhythms, amplitude of circadian rhythms, and total activity of the strains of three Tribolium species that were artificially selected for the death‐feigning duration: short (S‐strains) and long (L‐strains) durations. As a result, the amplitude of circadian rhythms and total activity significantly differed between S‐ and L‐strains, but there was no difference in the free‐running periods of the rhythm between the strains, in T. castaneum, T. confusum, and T. freemani. Although the relationship between death‐feigning behavior and activity has been reported for all three species, a genetic relationship between the duration of death feigning and the amplitude of circadian rhythms has been newly found in the present study.
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