Structural and Functional Alterations of Subcutaneous Small Resistance Arteries in Severe Human Obesity

Obese persons are at increased cardiovascular risk and exhibit increased arterial stiffness and impaired endothelial function of large‐ and medium‐size arteries. We hypothesized that normotensive subjects suffering from severe obesity would also present remodeling and endothelial dysfunction of small resistance arteries. A total of 16 lean (age: 49.6 ± 2.9 years, BMI: 22.9 ± 0.3 kg/m², mean ± s.e.m.) and 17 age‐matched severely obese (BMI: 41.1 ± 2.3 kg/m²) normotensive subjects were investigated. None had glucose or lipid metabolic abnormalities except for insulin resistance. Resistance arteries, dissected from abdominal subcutaneous tissue, were assessed on a pressurized myograph. For superimposable blood pressure, the media thickness, media cross‐sectional area (CSA), and media‐to‐lumen ratio values of resistance arteries were markedly and significantly greater in obese compared to lean subjects (media thickness 26.3 ± 0.6 vs. 16.2 ± 0.6 µm, CSA 22,272 ± 1,339 vs. 15,183 ± 1,186 µm², and media‐to‐lumen ratio 0.113 ± 0.006 vs. 0.059 ± 0.001, respectively, P < 0.01). Acetylcholine‐induced relaxation was impaired in vessels from obese subjects compared to the lean individuals (?40.4 ± 1.3%, P < 0.01), whereas endothelium‐independent vasorelaxation was similar in all groups. Stiffness of small arteries as assessed by the stress/strain relationship was similar in lean and severely obese subjects. We conclude that severe human obesity is associated with profound alterations in structural and functional characteristics of small arteries, which may be responsible for the presence of elevated cardiovascular risk and increased incidence of coronary, cerebrovascular and renal events reported in obesity.     

Masting uncoupling: mast seeding does not follow all mast flowering episodes in a dioecious juniper tree

Evolutionary selective forces, like predator satiation and pollination efficiency, are acknowledged to be major causes of masting (the variable, periodic and synchronic production of seeds in a population). However, a number of recent studies indicate that resources might also play an important role on shaping masting patterns. Dioecious masting species offer a privileged framework to study the role of resources on masting variation, since male and female plants often experience different reproductive costs and selective pressures. We followed masting and reproductive investment (RI) of the dioecious tree Juniperus thurifera in two populations along 10 years and studied the different response of males and females to experimentally increased water and nutrient availability in a third population. Juniperus thurifera females invested in reproduction three times more resources than males. Such disparity generated different resource‐use strategies in male and female trees. Tree‐ring growth and water use efficiency (WUE) confirmed that sexes differed in their resource investment temporal pattern, with males using current resources for reproduction and females using resources accumulated during longer periods. Watered and fertilized female trees presented significantly higher flowering reproductive investments than males and experienced an extraordinary mast‐flowering event. However, seeding RI and mast seeding were not affected by the treatment. This suggests that although resource availability affects the reproductive output of this species, there are other major forces regulating masting on J. thurifera. During 10 years, J. thurifera male and female trees presented high and low flowering years more or less synchronously. However, not all mast flowering episodes resulted in mast seeding, leading to masting uncoupling between flowering and seeding. Since flowering costs represent only 1% of females’ total reproductive investments, masting uncoupling could be a beneficial bet‐hedging strategy to maximize reproductive output in spite of unpredictable catastrophic events.     

Social effects on fruit fly courtship song

Courtship behavior in Drosophila has often been described as a classic innate behavioral repertoire, but more recently extensive plasticity has been described. In particular, prior exposure to acoustic signals of con‐ or heterspecific males can change courtship traits in both sexes that are liable to be important in reproductive isolation. However, it is unknown whether male courtship song itself is socially plastic. We examined courtship song plasticity of two species in the Drosophila melanogaster subgroup. Sexual isolation between the species is influenced by two male song traits, the interpulse interval (IPI) and sinesong frequency (SSF). Neither of these showed plasticity when males had prior experience of con‐ and heterospecific social partners. However, males of both species produced longer bursts of song during courtship when they were exposed to social partners (either con‐ or heterospecific) than when they were reared in isolation. D. melanogaster carrying mutations affecting short‐ or medium‐term memory showed a similar response to the social environment, not supporting a role for learning. Our results demonstrate that the amount of song a male produces during courtship is plastic depending on the social environment, which might reflect the advantage of being able to respond to variation in intrasexual competition, but that song structure itself is relatively inflexible, perhaps due to strong selection against hybridization.     

Untangling associations between chironomid taxa in Neotropical streams using local and landscape filters

1. Analyses of species association have major implications for selecting indicators for freshwater biomonitoring and conservation, because they allow for the elimination of redundant information and focus on taxa that can be easily handled and identified. These analyses are particularly relevant in the debate about using speciose groups (such as the Chironomidae) as indicators in the tropics, because they require difficult and time‐consuming analysis, and their responses to environmental gradients, including anthropogenic stressors, are poorly known. 2. Our objective was to show whether chironomid assemblages in Neotropical streams include clear associations of taxa and, if so, how well these associations could be explained by a set of models containing information from different spatial scales. For this, we formulated a priori models that allowed for the influence of local, landscape and spatial factors on chironomid taxon associations (CTA). These models represented biological hypotheses capable of explaining associations between chironomid taxa. For instance, CTA could be best explained by local variables (e.g. pH, conductivity and water temperature) or by processes acting at wider landscape scales (e.g. percentage of forest cover). 3. Biological data were taken from 61 streams in Southeastern Brazil, 47 of which were in well‐preserved regions, and 14 of which drained areas severely affected by anthropogenic activities. We adopted a model selection procedure using Akaike’s information criterion to determine the most parsimonious models for explaining CTA. 4. Applying Kendall’s coefficient of concordance, seven genera (Tanytarsus/Caladomyia, Ablabesmyia, Parametriocnemus, Pentaneura, Nanocladius, Polypedilum and Rheotanytarsus) were identified as associated taxa. The best‐supported model explained 42.6% of the total variance in the abundance of associated taxa. This model combined local and landscape environmental filters and spatial variables (which were derived from eigenfunction analysis). However, the model with local filters and spatial variables also had a good chance of being selected as the best model. 5. Standardised partial regression coefficients of local and landscape filters, including spatial variables, derived from model averaging allowed an estimation of which variables were best correlated with the abundance of associated taxa. In general, the abundance of the associated genera tended to be lower in streams characterised by a high percentage of forest cover (landscape scale), lower proportion of muddy substrata and high values of pH and conductivity (local scale). 6. Overall, our main result adds to the increasing number of studies that have indicated the importance of local and landscape variables, as well as the spatial relationships among sampling sites, for explaining aquatic insect community patterns in streams. Furthermore, our findings open new possibilities for the elimination of redundant data in the assessment of anthropogenic impacts on tropical streams.     

An Ultralong Lifespan and Low‐Temperature Workable Sodium‐Ion Full Battery for Stationary Energy Storage

Presently, commercialization of sodium‐ion batteries (SIBs) is still hindered by the relatively poor energy‐storage performance. In addition, low‐temperature (low‐T) Na storage is another principal concern for the wide application of SIBs. Unfortunately, the Na‐transfer kinetics is extremely sluggish at low‐T, as a result, there are few reports on low‐T SIBs. Here, an advanced low‐T sodium‐ion full battery (SIFB) assembled by an anode of 3D Se/graphene composite and a high‐voltage cathode (Na₃V₂(PO₄)₂O₂F) is developed, exhibiting ultralong lifespan (over even 15 000 cycles, the capacity retention is still up to 86.3% at 1 A g^?1), outstanding low‐T energy storage performance (e.g., all values of capacity retention are >75% after 1000 cycles at temperatures from 25 to ?25 °C at 0.4 A g^?1), and high‐energy/power properties. Such ultralong lifespan signifies that the developed sodium‐ion full battery can be used for longer than 60 years, if batteries charge/discharge once a day and 80% capacity retention is the standard of battery life. As a result, the present study not only promotes the practicability and commercialization of SIBs but also points out the new developing directions of next‐generation energy storage for wider range applications.     

Ecomorphological convergence in Eleutherodactylus frogs: a case of replicate radiations in the Caribbean

Replicate radiations, the repeated multiplication of species associated with ecological divergence, have attracted much attention and generated as much debate. Due to the few well‐studied cases, it remains unclear whether replicate radiations are an exceptional result of evolution or a relatively common example of the power of adaptation by natural selection. We examined the case of Eleutherodactylus frogs, which radiated in the Caribbean islands resulting in more than 160 species that occupy very diverse habitats. A time‐calibrated phylogeny revealed that these frogs independently diversified on all larger islands producing species that occupy a broad range of microhabitats in different islands. Using phylogenetic comparative methods, we found an association between morphological traits and particular microhabitats, and for most microhabitats detected significant morphological convergence. Our results indicate Caribbean Eleutherodactylus are a novel example of replicate radiations, and highlight the predictability of evolutionary processes, as similar ecological opportunities can lead to similar outcomes.     

Seventy years of changes in the abundance of Danish charophytes

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Methylphenidate decreased the amount of glucose needed by the brain to perform a cognitive task

The use of stimulants (methylphenidate and amphetamine) as cognitive enhancers by the general public is increasing and is controversial. It is still unclear how they work or why they improve performance in some individuals but impair it in others. To test the hypothesis that stimulants enhance signal to noise ratio of neuronal activity and thereby reduce cerebral activity by increasing efficiency, we measured the effects of methylphenidate on brain glucose utilization in healthy adults. We measured brain glucose metabolism (using Positron Emission Tomography and 2-deoxy-2[18F]fluoro-D-glucose) in 23 healthy adults who were tested at baseline and while performing an accuracy-controlled cognitive task (numerical calculations) given with and without methylphenidate (20 mg, oral). Sixteen subjects underwent a fourth scan with methylphenidate but without cognitive stimulation. Compared to placebo methylphenidate significantly reduced the amount of glucose utilized by the brain when performing the cognitive task but methylphenidate did not affect brain metabolism when given without cognitive stimulation. Whole brain metabolism when the cognitive task was given with placebo increased 21% whereas with methylphenidate it increased 11% (50% less). This reflected both a decrease in magnitude of activation and in the regions activated by the task. Methylphenidate's reduction of the metabolic increases in regions from the default network (implicated in mind-wandering) was associated with improvement in performance only in subjects who activated these regions when the cognitive task was given with placebo. These results corroborate prior findings that stimulant medications reduced the magnitude of regional activation to a task and in addition document a "focusing" of the activation. This effect may be beneficial when neuronal resources are diverted (i.e., mind-wandering) or impaired (i.e., attention deficit hyperactivity disorder), but it could be detrimental when brain activity is already optimally focused. This would explain why methylphenidate has beneficial effects in some individuals and contexts and detrimental effects in others.     

Indoor Thin‐Film Photovoltaics: Progress and Challenges

Energy generation and consumption have always been an important component of social development. Interests in this field are beginning to shift to indoor photovoltaics (IPV) which can serve as power sources under low light conditions to meet the energy needs of rapidly growing fields, such as intelligence gathering and information processing which usually operate via the Internet‐of‐things (IoT). Since the power requirements for this purpose continue to decrease, IPV systems under low light may facilitate the realization of self‐powered high‐tech electronic devices connected through the IoT. This review discusses and compares the characteristics of different types of IPV devices such as those based on silicon, dye, III‐V semiconductors, organic compounds, and halide perovskites. Among them, specific attention is paid to perovskite photovoltaics which may potentially become a high performing IPV system due to the fascinating photophysics of the halide perovskite active layer. The limitations of such indoor application as they relate to the toxicity, stability, and electronic structure of halide perovskites are also discussed. Finally, strategies which could produce highly functional, nontoxic, and stable perovskite photovoltaics devices for indoor applications are proposed.