Age‐Related Differences in Daily Attention Patterns in Preschool,Kindergarten, First‐Grade,and Fifth‐Grade Pupils

The purpose of this study was to examine age‐related differences in the daily attention patterns of preschool, kindergarten, first‐grade, and fifth‐grade pupils by means of a cross‐sectional sample of 4–11‐year‐old French students. The importance of this study comes from the need to understand attention and apply the information it provides in educational settings. The first study conducted in a school setting with three age groups (4–5‐, 6–7‐, and 10–11‐year‐olds) demonstrated a rapid rhythmicity (60 minute period) for preschoolers (4–5 years old), with higher performance at the beginning of a teaching session. This pattern evolved until the fifth grade (10–11‐year‐olds), after which the temporal variation in attention was comparable to that of working adults, with fluctuations occurring on a half‐day basis. The children's scores on crossing‐out tests rose during the morning, declined in the early afternoon, and then rose again later during the afternoon. The second study enhanced our understanding of the change of the rhythm in attention of 4–7‐year‐old pupils. The rapid daily rhythmicity, linked to a session effect, seems to gradually disappear as children move from preschool 2 to kindergarten (4–5‐ to 5–6‐year‐olds) and then on to first grade (6–7‐year‐olds), where the daily attention patterns are closer to the standard pattern found by chronopsychology studies. The evolving patterns obtained from group means were confirmed by analysis of individual patterns. Exploratory statistical analysis of the data provided greater detail on the observed interindividual patterns, indicating that within each school grade, the attention patterns of some children are similar to the standard pattern while the attention patterns of others are more atypical. Deviations were mainly found in the 5–6‐year‐old age range (kindergarteners). The greatest ‘mixture’ of patterns was observed in the kindergartners (5–6‐year‐olds). Age plays a role not only in modifying daily changes but also in the distribution of interindividual differences in daily fluctuations, which occur most when children are of kindergarten age (5–6 years of age).     

Origins of Balance Disorders during a Daily Living Movement in Obese: Can Biomechanical Factors Explain Everything?

Obese people suffer from postural deficits and are more subject to falls than their lean counterpart. To improve prevention and post-fall rehabilitation programs, it seems important to better understand the posturo-kinetic disorders in daily life situations by determining the contribution of some key factors, mainly morphological characteristics and physical activity level, in the apparition of these disorders.Twelve severe android obese and eight healthy non obese adults performed a reaching task mobilizing the whole body. To further determine the origin of the postural and motor behavior differences, non obese individuals also performed an experimental session with additional constraints which simulated some of the obese morphological characteristics. Impact of the sedentary lifestyle was also studied by dissociation of the obese in two subgroups: physically « active » and physically « inactive ». Movement kinetics and kinematics were characterized with an optoelectronic system synchronized to a force platform. The mechanical equilibrium pattern was evaluated through the displacements of the Centre of Mass (CoM) and the centre of foot pressure within the Base of Support (BoS).Results showed that obesity decreased movement speed (≈−23%, p<0.01), strongly increased CoM displacement (≈+30%, p<0.05) and induced an important spatio-temporal desynchronization (≈+40%, p<0.05) of the focal and postural components of the movement during the transition between the descending and ascending movements.The role of some morphological characteristics and of physical activity on obese patients'' postural control disorder is discussed and set back in the more general context of overall factors contributing to postural deficits with obesity.     

Perovskite Solar Cells: Can We Go Organic‐Free,Lead‐Free,and Dopant‐Free?

Having demonstrated incredibly fast progress in power conversion efficiency, rising to a level comparable with that of crystalline silicon cells, lead‐based organic–inorganic hybrid perovskite solar cells are now facing the stability tests needed for industrialization. Poor thermal stability (<150 °C) owing to organic constituents and interlayer diffusion of materials (dopants), and environmental incompatibility due to Pb has surged the development of organic‐free, Pb‐free perovskites and dopant‐free hole transport materials (HTMs). The recent rapid increase in efficiency of cells based on inorganic perovskites, crossing 18%, demonstrates the great potential of inorganic perovskites as thermally stable and high‐efficiency cells. Although all kinds of Pb‐free perovskites lag in efficiency in comparison to the hybrid and inorganic perovskites, they also demonstrate better structural and environmental stability. The performance of dopant‐free HTMs matching/surpassing dopant‐containing HTMs makes the former a better choice for stability. Even though the efforts to enhance the stability of Pb‐based hybrid perovskites should continue by different techniques, organic‐free and lead‐free perovskites, and dopant‐free HTMs must be pursued with greater interest for the future. This review describes the present issues and possible strategies to address them, and thus will help to improve the overall performance of robust organic‐free, Pb‐free, and dopant‐free perovskite solar cells.     

Circadian Rhythms in Heart Rate,Motility, and Body Temperature of Wild‐type C57 and eNOS Knock‐out Mice Under Light‐dark,Free‐run,and After Time Zone Transition

The nitric oxide (NO) system is involved in the regulation of the cardiovascular system in controlling central and peripheral vascular tone and cardiac functions. It was the aim of this study to investigate in wild‐type C57BL/6 and endothelial nitric oxide synthase (eNOS) knock‐out mice (eNOS‐/‐) the contribution of NO on the circadian rhythms in heart rate (HR), motility (motor activity [MA]), and body temperature (BT) under various environmental conditions. Experiments were performed in 12∶12 h of a light:dark cycle (LD), under free‐run in total darkness (DD), and after a phase delay shift of the LD cycle by ?6 h (i.e., under simulation of a westward time zone transition). All parameters were monitored by radiotelemetry in freely moving mice. In LD, no significant differences in the rhythms of HR and MA were observed between the two strains of mice. BT, however, was significantly lower during the light phase in eNOS‐/‐ mice, resulting in a significantly greater amplitude. The period of the free‐running rhythm in DD was slightly shorter for all variables, though not significant. In general, rhythmicity was greater in eNOS‐/‐ than in C57 mice both in LD and DD. After a delay shift of the LD cycle, HR and BT were resynchronized to the new LD schedule within 5–6 days, and resynchronization of MA occurred within 2–3 days. The results in telemetrically instrumented mice show that complete knock‐out of the endothelial NO system—though expressed in the suprachiasmatic nuclei and in peripheral tissues—did not affect the circadian organization of heart rate and motility. The circadian regulation of the body temperature was slightly affected in eNOS‐/‐ mice.     

Tidal,Daily, and Lunar‐Day Activity Cycles in the Marine Polychaete Nereis virens

The burrow emergence activity of the wild caught ragworm Nereis virens Sars associated with food prospecting was investigated under various photoperiodic (LD) and simulated tidal cycles (STC) using a laboratory based actograph. Just over half (57%) of the animals under LD with STC displayed significant tidal (～12.4 h) and/or lunar‐day (～24.8 h) activity patterns. Under constant light (LL) plus a STC, 25% of all animals were tidal, while one animal responded with a circadian (24.2 h) activity rhythm suggestive of cross‐modal entrainment where the environmental stimulus of one period entrains rhythmic behavior of a different period. All peaks of activity under a STC, apart from that of the individual cross‐modal entrainment case, coincided with the period of tank flooding. Under only LD without a STC, 49% of the animals showed nocturnal (～24 h) activity. When animals were maintained under free‐running LL conditions, 15% displayed significant rhythmicity with circatidal and circadian/circalunidian periodicities. Although activity cycles in N. virens at the population level are robust, at the individual level they are particularly labile, suggesting complex biological clock‐control with multiple clock output pathways.     

The Potential Distribution of Invading Helicoverpa armigera in North America: Is It Just a Matter of Time?

Helicoverpa armigera has recently invaded South and Central America, and appears to be spreading rapidly. We update a previously developed potential distribution model to highlight the global invasion threat, with emphasis on the risks to the United States. The continued range expansion of H. armigera in Central America is likely to change the invasion threat it poses to North America qualitatively, making natural dispersal from either the Caribbean islands or Mexico feasible. To characterise the threat posed by H. armigera, we collated the value of the major host crops in the United States growing within its modelled potential range, including that area where it could expand its range during favourable seasons. We found that the annual value of crops that would be exposed to H. armigera totalled approximately US$78 billion p.a., with US$843 million p.a. worth growing in climates that are optimal for the pest. Elsewhere, H. armigera has developed broad-spectrum pesticide resistance; meaning that if it invades the United States, protecting these crops from significant production impacts could be challenging. It may be cost-effective to undertake pre-emptive biosecurity activities such as slowing the spread of H. armigera throughout the Americas, improving the system for detecting H. armigera, and methods for rapid identification, especially distinguishing between H. armigera, H. zea and potential H. armigera x H. zea hybrids. Developing biological control programs, especially using inundative techniques with entomopathogens and parasitoids could slow the spread of H. armigera, and reduce selective pressure for pesticide resistance. The rapid spread of H. armigera through South America into Central America suggests that its spread into North America is a matter of time. The likely natural dispersal routes preclude aggressive incursion responses, emphasizing the value of preparatory communication with agricultural producers in areas suitable for invasion by H. armigera.     

Sex Difference in Sleep‐Time Preference and Sleep Need: A Cross‐Sectional Survey among Italian Pre‐Adolescents,Adolescents, and Adults

The aim of this study was to examine sex differences in sleep‐time preference by age among Italian pre‐adolescents, adolescents, and adults. The final sample consisted of 8,972 participants (5,367 females and 3,605 males) from 10 to 87 yrs of age. To assess preferred sleep habits, we considered the answers to the open‐ended questions of the Morningness‐Eveningness Questionnaire (MEQ). In agreement with previous studies, we found that sleep‐time preference started to shift toward eveningness from the age of 13 yrs. Females reached their peak in eveningness earlier (about 17 yrs of age) than males (about 21 yrs of age). Thereafter, the ideal sleep‐time preference advanced in men and women with increasing age. Females presented a more significant advanced sleep phase than males only during the years when sexual hormones are typically active. Moreover, females reported a longer ideal sleep duration than males across all age groups examined, except in over 55 yrs one. (Author correspondence: vincenzo.natale@unibo.it)     

Potential role of α-synuclein in neurodegeneration: studies in a rat animal model

Neuronal protein α-synuclein (α-syn) is an essential player in the development of neurodegenerative diseases called synucleinopathies. A spontaneous autosomal recessive rat model for neurodegeneration was developed in our laboratory. These rats demonstrate progressive increases in α-syn in the brain mesencephalon followed by loss of dopaminergic terminals in the basal ganglia (BG) and motor impairments. The severity of pathology is directly related to the overexpression of α-syn and parallel decrease in dopamine (DA) level in the striatum (ST) of affected rats. The neurodegeneration in this model is characterized by the presence of perikarya and neurites Lewis bodies (LB) and diffuse marked accumulation of perikaryal α-syn in the substantia nigra (SN), brain stem (BS), and striatum (ST) along with neuronal loss. Light and ultrastructural analyses revealed that the process of neuronal degeneration is a 'dying back' type. The disease process is accompanied by gliosis and release of inflammatory cytokines. This neurodegeneration is a multisystemic disease and implicate α-syn as a major factor in the pathogenesis of this inherited autosomal recessive animal model. Decrease dopamine (DA) and overexpression of α-syn in the brain mesencephalon may provide a naturally occurring animal model for Parkinson's disease (PD) and other synucleinopathies that reproduces significant pathological, neurochemical, and behavioral features of the human disease.     

Quantitative mRNA Analysis of Eight Bovine 5‐HT Receptor Subtypes in Brain,Abomasum, and Intestine by Real‐Time RT‐PCR

Abstract

Serotoninergic pathways are involved in economically important bovine gastrointestinal (GI) motility disorders such as displaced abomasum and cecal dilatation/dislocation. The existing research tools to investigate the role of serotoninergic pathways in such disorders in ruminants comprise functional pharmacological methods, e.g., in vitro contractility studies in tissue baths, and electromyographical recordings in vivo. However, no tools for quantification of bovine serotonin receptor [5‐hydroxytryptamine receptor (5‐HTR)] expression were available so far. This study aimed to develop real‐time RT‐PCR assays for quantitative mRNA analysis of bovine 5‐HTR subtypes. Because the bovine 5‐HTR coding sequences (CDSs) were completely unknown, multiple species (human, mouse, and rat) alignment of complete CDS was used for primer design in highly homologous regions. LightCycler real‐time RT‐PCR assays (partial CDS) for the following bovine 5‐HTR subtypes were developed and validated: 5‐HTR_1A, 5‐HTR_1B, 5‐HTR_1D, 5‐HTR_1F, 5‐HTR_2A, 5‐HTR_2B, 5‐HTR_2C, and 5‐HTR₄. Intra‐ and inter‐assay coefficients of variation (CV) for the eight established assays were small, ranging from 0.49% to 2.46%. As a first physiological application, 5‐HTR mRNA expression levels were measured in brain, abomasum, and intestine of 10 healthy, lactating dairy cows. The 5‐HTR expression was quantified by normalization to the housekeeping gene glyceraldehyde‐phosphate‐dehydrogenase (GAPDH). The 5‐HTR subtype expression levels ranged from 0.001% (5‐HTR_2C in intestine) to 1% 5‐HTR/GAPDH (5‐HTR_1B and 5‐HTR₄ in intestine). There were high variations of 5‐HTR subtype mRNA expression within tissues across receptor subtypes and within receptor subtypes across tissues. In conclusion, accurate real‐time RT‐PCR assays for quantitative analysis of bovine 5‐HTR subtype gene expression were developed and validated.     

Measuring Phase Shifts in Humans Following a Simulated Time‐Zone Transition: Agreement Between Constant Routine and Purification Methods

Twelve healthy participants were studied in an Isolation Unit. For the first 7 (control) days, subjects lived on UK time. Then the clock was advanced by 8 h, mimicking an eastward time‐zone transition, and for days 8 to 12, participants lived on this new local time. Two constant routines (participants were not allowed to sleep, were restricted in movement, and ate regular, identical snacks) were undertaken, during the control days (days 3 to 4) and at the end of the experiment (days 11 to 12). Rectal temperature and activity were measured throughout, with activity used to correct the measured temperatures for the direct (masking) effects of the sleep‐wake cycle. Phase changes of the temperature rhythm between the constant routines were assessed by cross‐correlation and cosinor analysis. During days 8 to 10, the measured temperatures and those that had been corrected (purified) for masking were assessed by the same two methods, and the shifts were extrapolated to predict the values expected during the second constant routine. Individuals differed widely in the phase shifts of the temperature rhythm, but the correlations between the changes measured by constant routines and those estimated by the purification methods were high (r=0.771 to 0.903), and the differences between them were not significantly different from zero (p>0.24). Phase shifts of the measured (masked) temperature rhythm were poorer predictors of the shift obtained from the constant routines (r≤0.605; mean±SD of differences >3±4.5 h). Limitations of the methods due to the variability of results are discussed, but we conclude that the mean phase shifts obtained from purified, but not raw, temperature data show acceptable agreement with those found using our version of the constant routine.     

Artificial ponds: a substitute for natural Beaver ponds in a Central European Highland (Eifel,Germany)?

Stormwater ponds are increasingly common aquatic habitats whose biotic communities are largely unexplored. As anthropogenic development continues to alter the landscape, watershed land use is gaining recognition for its potential to predict species compositions in aquatic systems. This study reports species composition of five aquatic hemipteran families (Notonectidae, Corixidae, Belostomatidae, Nepidae, Pleidae) in 28 permanent, artificial stormwater ponds in watersheds with different land covers and associated contaminant input. We hypothesized that land cover variables would be significant drivers of aquatic hemipteran community structure in ponds, and that ponds with a high percentage of agricultural and lawn cover in the watershed would be characterized by the absence of species intolerant of the chemical, physical, and ultimately biotic changes associated with these watersheds. Non-metric multi-dimensional scaling (NMS) was used to identify dominant gradients of species composition and environmental variables. Pond morphology variables, watershed lawn, watershed agriculture, and predatory fish abundance were each found to have statistically significant correlations with hemipteran community structure. The abundance of Notonecta undulata, the species responsible for creating the largest (ranked) distance in species structure among ponds, was positively correlated with shallow, fishless ponds and independent of land use variables. The abundances of four species of corixids were negatively correlated with watershed agriculture, and hemipteran richness was positively correlated with watershed lawn and negatively correlated with pond surface area. Heirarchical cluster analysis revealed non-random hemipteran species assemblages in which congeneric corixid species tended to co-occur, contradicting traditional niche theory. Since artificial stormwater ponds are chemically different from natural-pond habitat and rapidly increasing in number, knowledge of which insect species are capable of thriving in this environment and their relationship to land use in the watershed is of both environmental and evolutionary interest. Handling editor: D. Dudgeon     

The Free Caesareans Policy in Low-Income Settings: An Interrupted Time Series Analysis in Mali (2003–2012)

Introduction

Several countries have instituted fee exemptions for caesareans to reduce maternal and newborn mortality.

Objectives

To evaluate the effect of fee exemptions for caesareans on population caesarean rates taking into account different levels of accessibility.

Methods

The observation period was from January 2003 to May 2012 in one Region and covered 11.7 million person-years. Exemption fees for caesareans were adopted on June 26, 2005. Data were obtained from a registration system implemented in 2003 that tracks all obstetrical emergencies and interventions including caesareans. The pre-intervention period was 30 months and the post-intervention period was 83 months. We used an interrupted time series to evaluate the trend before and after the policy adoption and the overall tendency.

Findings

During the study period, the caesarean rate increased from 0.25 to 1.5% for the entire population. For women living in cities with district hospitals that provided caesareans, the rate increased from 1.7% before the policy was enforced to 5.7% 83 months later. No significant change in trends was observed among women living in villages with a healthcare centre or those in villages with no healthcare facility. For the latter, the caesarean rate increased from 0.4 to 1%.

Conclusions

After nine years of implementation policy in Mali, the caesarean rate achieved in cities with a district hospital reached the full beneficial effect of this measure, whereas for women living elsewhere this policy did not increase the caesarean rate to a level that could contribute effectively to reduce their risk of maternal death. Only universal access to this essential intervention could reduce the inequities and increase the effectiveness of this policy.     

Sleep Length as a Function of Morning Shift‐Start Time in Irregular Shift Schedules for Train Drivers: Self‐Rated Health and Individual Differences

Forty‐six male train drivers (mean age=46.5, SD=5.1) were recruited to participate in a diary study for 14 consecutive days with questions about their sleep and working hours. A polynomial mixed‐effect regression model showed a curvilinear relation (p <. 001) between shift‐start time and sleep duration for shifts starting at 03∶00–12∶00 h and with a near linear increase for ones starting between 04∶30 and 09∶00 h of approximately 0.7 h for every 1 h the shift was delayed. The longest sleeps were estimated at ～8 h before shifts that started at ～10∶00 h. The shortest sleeps were found for shifts that started before 04∶30 h and were estimated at ～5 h. Individual differences were estimated with a random-effect standard deviation of 0.51 h, independent of shift‐start time (p =.005). One‐half of the between‐subject variance was explained by subjective health. A one‐step decrease in health was associated with a 26 min increase in sleep length. The results have practical implications for constructing shift schedules. Early morning shifts reduced sleep length substantially and should be mixed with later start hours to avoid the accumulation of sleep dept. Delaying the shift‐start past 10∶00 h had little effect on sleep opportunity; however, delaying shift‐start to between 04∶30 and 9∶00 h had a strong impact on sleep length, with 70% of the extra time used for sleep, suggesting large positive effects for this range of shift‐start times.     

The mitochondrial‐derived peptide MOTS‐c: a player in exceptional longevity?

Mitochondrial‐derived peptides (MDP) are encoded by functional short open reading frames in the mitochondrial DNA (mtDNA). These include humanin, and the recently discovered mitochondrial open reading frame of the 12S rRNA‐c (MOTS‐c). Although more research is needed, we suggest that the m.1382A>C polymorphism located in the MOTS‐c encoding mtDNA, which is specific for the Northeast Asian population, may be among the putative biological mechanisms explaining the high longevity of Japanese people.     

Frequency‐dependent selection: a diversifying force in microbial populations

The benefits of “bet‐hedging” strategies have been assumed to be the main cause of phenotypic diversity in biological populations. However, in their recent work, Healey et al ( 2016 ) provide experimental support for negative frequency‐dependent selection (NFDS) as an alternative driving force of diversity. NFDS favors rare phenotypes over common ones, resulting in an evolutionarily stable mixture of phenotypes that is not necessarily optimal for population growth.