Energetic Input Research Articles

Key components of mechanical work predict outcomes in robotic stroke therapy

BackgroundClinical practice typically emphasizes active involvement during therapy. However, traditional approaches can offer only general guidance on the form of involvement that would be most helpful to recovery. Beyond assisting movement, robots allow comprehensive methods for measuring practice behaviors, including the energetic input of the learner. Using data from our previous study of robot-assisted therapy, we examined how separate components of mechanical work contribute to predicting training outcomes.MethodsStroke survivors (n = 11) completed six sessions in two-weeks of upper extremity motor exploration (self-directed movement practice) training with customized forces, while a control group (n = 11) trained without assistance. We employed multiple regression analysis to predict patient outcomes with computed mechanical work as independent variables, including separate features for elbow versus shoulder joints, positive (concentric) and negative (eccentric), flexion and extension.ResultsOur analysis showed that increases in total mechanical work during therapy were positively correlated with our final outcome metric, velocity range. Further analysis revealed that greater amounts of negative work at the shoulder and positive work at the elbow as the most important predictors of recovery (using cross-validated regression, R2 = 52%). However, the work features were likely mutually correlated, suggesting a prediction model that first removed shared variance (using PCA, R2 = 65–85%).ConclusionsThese results support robotic training for stroke survivors that increases energetic activity in eccentric shoulder and concentric elbow actions.Trial registrationClinicalTrials.gov, Identifier: NCT02570256. Registered 7 October 2015 – Retrospectively registered,

Caracterización del valor nutricional de los residuos agroindustriales para la alimentación de ganado vacuno en la región de San Martín, Perú

Se realizó una caracterización nutricional de 10 residuos agroindustriales disponibles en San Martín, Perú. Se colectaron 19 muestras de residuos provenientes de 11 plantas agroindustriales dedicadas a la producción de aceite de palma, arroz, cacao, café, coco y chontaduro. Se determinó la materia seca (MS), proteína cruda (PC), extracto etéreo (EE), fibra cruda (FC), extracto libre de nitrógeno (ELN), ceniza, digestibilidad aparente in vitro de la materia seca (DIVMS), fibra detergente neutro (FDN), fraccionamiento de proteína, proteína cruda utilizable (uCP), nutrientes digestibles totales (NDT) y energía neta de lactación (ENL). Se encontraron diferencias significativas entre subproductos con respecto a su potencial nutricional (p < 0,05), siendo el nielen, arrocillo y polvillo de arroz, insumos energéticos con valores altos de ENL (2,1 ± 0,02, 2,1 ± 0,02 y 1,7 ± 0,02 Mcal/kg en base seca, respectivamente) y alta DIVMS (99,3 ± 0,25 %, 90,5 ± 0,42 % y 99,0 ± 0,68 %, respectivamente). Insumos con mayor aporte proteico fueron torta de coco y cascarilla de cacao (21,9 % y 21,8 ± 1,34 % de pc, respectivamente). La fibra de palma y cascarilla de arroz fueron residuos fibrosos con menor potencial de uso por su baja DIVMS (27,8 ± 2,45 % y 27,7 ± 5,02 %, respectivamente) y alto contenido de FDN (69,8 ± 4,17 % y 72,6 ± 6,45 %, respectivamente). La cáscara de palmito tuvo regular DIVMS (57,2 %) y alto FDN (60,4 %). Los residuos agroindustriales de San Martín tienen un variado potencial energético y proteico de utilidad en la alimentación de ganado vacuno.

Formation of complex molecules in translucent clouds: acetaldehyde, vinyl alcohol, ketene, and ethanol via “nonenergetic” processing of C2H2ice

Context.Complex organic molecules (COMs) have been identified toward high- and low-mass protostars as well as molecular clouds, suggesting that these interstellar species originate from the early stage(s) of starformation. The reaction pathways resulting in COMs described by the formula C2HnO, such as acetaldehyde (CH3CHO), vinyl alcohol (CH2CHOH), ketene (CH2CO), and ethanol (CH3CH2OH), are still under debate. Several of these species have been detected in both translucent and dense clouds, where chemical processes are dominated by (ground-state) atom and radical surface reactions. Therefore, efficient formation pathways are needed to account for their appearance well before the so-called catastrophic CO freeze-out stage starts.Aims.In this work, we investigate the laboratory possible solid-state reactions that involve simple hydrocarbons and OH-radicals along with H2O ice under translucent cloud conditions (1 ≤AV≤ 5 andnH~ 103cm−3). We focus on the interactions of C2H2with H-atoms and OH-radicals, which are produced along the H2O formation sequence on grain surfaces at 10 K.Methods.Ultra-high vacuum experiments were performed to study the surface chemistry observed during C2H2+ O2+ H codeposition, where O2was used for the in situ generation of OH-radicals. These C2H2experiments were extended by a set of similar experiments involving acetaldehyde (CH3CHO) – an abundant product of C2H2+ O2+ H codeposition. Reflection absorption infrared spectroscopy was applied to in situ monitor the initial and newly formed species. After that, a temperature-programmed desorption experiment combined with a quadrupole mass spectrometer was used as a complementary analytical tool. The IR and QMS spectral assignments were further confirmed in isotope labeling experiments using18O2.Results.The investigated 10 K surface chemistry of C2H2with H-atoms and OH-radicals not only results in semi and fully saturated hydrocarbons, such as ethylene (C2H4) and ethane (C2H6), but it also leads to the formation of COMs, such as vinyl alcohol, acetaldehyde, ketene, ethanol, and possibly acetic acid. It is concluded that OH-radical addition reactions to C2H2, acting as a molecular backbone, followed by isomerization (i.e., keto-enol tautomerization) via an intermolecular pathway and successive hydrogenation provides so far an experimentally unreported solid-state route for the formation of these species without the need of energetic input. The kinetics of acetaldehyde reacting with impacting H-atoms leading to ketene and ethanol is found to have a preference for the saturated product. The astronomical relevance of the reaction network introduced here is discussed.

Space-independent community and hub structure of functional brain networks

Coordinated brain activity reflects underlying cognitive processes and can be modeled as a network of inter-regional functional connections. The most costly connections in the network are long-distance correlations that, in the absence of underlying structural connections, are maintained by sustained energetic inputs. Here, we present a spatial modeling approach that amplifies contributions made by long-distance functional connections to whole-brain network architecture, while simultaneously suppressing contributions made by short-range connections. We use this method to characterize the long-distance architecture of functional networks and to identify aspects of community and hub structure that are driven by long-distance correlations and that, we argue, are of greater functional significance. We find that based only on patterns of long-distance connectivity, primary sensory cortices occupy increasingly central positions and appear more “hub-like”. Additionally, we show that the community structure of long-distance connections spans multiple topological levels and differs from the community structure detected in networks that include both short-range and long-distance connections. In summary, these findings highlight the complex relationship between the brain’s physical layout and its functional architecture. The results presented here inform future analyses of community structure and network hubs in health, across development, and in the case of neuropsychiatric disorders.

Revisiting energy efficiency, renewability, and sustainability indicators in biofuels life cycle: Analysis and standardization proposal

Abstract Life Cycle Energy Analysis (LCEA) has been widely used for net energy balance and energy ratio calculation, expressing the overall efficiency, renewability, and sustainability of biofuels production. However, over 27 methodologies have been found in the literature, representing a barrier for the comparison between different studies. The aim of this research is to discuss the main LCEA indicators methodologies and to propose a more comprehensive and user-friendly system of standard equations for the calculation of energy efficiency indicators, considering allocation criteria and renewability of energetic inputs. The standardized equations were evaluated via their application in two case studies related to sugarcane ethanol and biodiesel production and the results were compared to evaluate the influence of allocation criteria and inputs characteristics (renewable and non-renewable) in both attributional and consequential LCEA. As a result, 10 methodologies were proposed in order to standardize those 27 energy indicators. It was observed a significant variation in energy values depending on the use of allocation criteria, which were 114–468% for attributional LCEA and 114–387% for consequential LCEA in ethanol production, and between a range of 106–147% for attributional LCEA and 159–212% for consequential LCEA, in biodiesel production. The consideration of renewable energy inputs resulted in energy variations between 99 and 428% (attributional LCEA) and 61–268% (consequential LCEA) in ethanol production and between 47 and 76% (attributional LCEA) and 78–114% (consequential LCEA) in biodiesel production. Also, results showed that allocation criteria, input characteristics, and LCEA approach have a significant influence on the energy balance. Standardized methodologies proposed for energy balance equations in a biofuel production system make easier the application, understanding, and comparison among results of an LCEA.

Cosmic rays or turbulence can suppress cooling flows (where thermal heating or momentum injection fail)

ABSTRACT The quenching ‘maintenance’ and ‘cooling flow’ problems are important from the Milky Way through massive cluster elliptical galaxies. Previous work has shown that some source of energy beyond that from stars and pure magnetohydrodynamic processes is required, perhaps from active galactic nuclei, but even the qualitative form of this energetic input remains uncertain. Different scenarios include thermal ‘heating’, direct wind or momentum injection, cosmic ray heating or pressure support, or turbulent ‘stirring’ of the intracluster medium (ICM). We investigate these in $10^{12}\!-\!10^{14}\, {\rm M}_{\odot }$ haloes using high-resolution non-cosmological simulations with the FIRE-2 (Feedback In Realistic Environments) stellar feedback model, including simplified toy energy injection models, where we arbitrarily vary the strength, injection scale, and physical form of the energy. We explore which scenarios can quench without violating observational constraints on energetics or ICM gas. We show that turbulent stirring in the central $\sim 100\,$ kpc, or cosmic ray injection, can both maintain a stable low-star formation rate halo for >Gyr time-scales with modest energy input, by providing a non-thermal pressure that stably lowers the core density and cooling rates. In both cases, associated thermal-heating processes are negligible. Turbulent stirring preserves cool-core features while mixing condensed core gas into the hotter halo and is by far the most energy efficient model. Pure thermal heating or nuclear isotropic momentum injection require vastly larger energy, are less efficient in lower mass haloes, easily overheat cores, and require fine tuning to avoid driving unphysical temperature gradients or gas expulsion from the halo centre.

Macroevolutionary evidence suggests trait-dependent coevolution between behavior and life-history.

Species with fast life-histories typically prioritize current over future reproductive events, compared to species with slow life-histories. These species therefore require greater energetic input into reproduction, and also likely have less time to realize their reproductive potential. Hence, behaviors that increase access to both resources and mating opportunities, at a cost of increased mortality risk, could coevolve with the pace of life-history. However, whether this prediction holds across species, remains untested under standardized conditions. Here, we test how risky behaviors, which facilitate access to resources and mating opportunities (i.e., activity, boldness, and aggression), along with metabolic rate, coevolve with the pace of life-history across 20 species of killifish that present remarkable divergences in the pace of life-history.We found a positive association between the pace of life-history and aggression, but interestingly not with other behavioral traits or metabolic rate. Aggression is linked to interference competition, and in killifishes is often employed to secure mates, while activity and boldness are more relevant for exploiting energetic resources. Our results suggest that the trade-off between current and future reproduction plays a more prominent role in shaping mating behavior, while behaviors related to energy acquisition may be influenced by ecological factors.

Biodiversity Improves Life Cycle Sustainability Metrics in Algal Biofuel Production.

Algal biofuel has yet to realize its potential as a commercial and sustainable bioenergy source, largely due to the challenge of maximizing and sustaining biomass production with respect to energetic and material inputs in large-scale cultivation. Experimental studies have shown that multispecies algal polycultures can be designed to enhance biomass production, stability, and nutrient recycling compared to monocultures. Yet, it remains unclear whether these impacts of biodiversity make polycultures more sustainable than monocultures. Here, we present results of a comparative life cycle assessment (LCA) for algal biorefineries to compare the sustainability metrics of monocultures and polycultures of six fresh-water algal species. Our results showed that when algae were grown in outdoor experimental ponds, certain bicultures improved the energy return on investment (EROI) and greenhouse gas emissions (GHGs) by 20% and 16%, respectively, compared to the best monoculture. Bicultures outperformed monocultures by performing multiple functions simultaneously (e.g., improved stability, nutrient efficiency, biocrude characteristics), which outweighed the higher productivity attainable by a monoculture. Our results demonstrate that algal polycultures with optimized multifunctionality lead to enhanced life cycle metrics, highlighting the significant potential of ecological engineering for enabling future environmentally sustainable algal biorefineries.

On the Conversion Efficiency of CO2 Electroreduction on Gold

Benjamin A. Zhang is a PhD student at Harvard University. His research focus is on the control of mass transport and concentration gradients in electrochemical reactions, in particular CO2 reduction, through nano- and mesostructuring of electrodes. Cyrille Costentin is Professor at Universite Paris Diderot. He received his undergraduate education at Ecole Normale Superieure de Cachan and his PhD at Universite Paris Diderot. He is currently a Visiting Scientist in the group of D.G. Nocera at Harvard University. His interests include mechanisms and reactivity in electron transfer chemistry with particular emphasis on proton-coupled electron transfer and catalysis of electrochemical reactions. Daniel G. Nocera is the Patterson Rockwood Professor of Energy at Harvard University. His group studies mechanisms of biological and chemical energy conversion.

Influence of pulsed and continuous wave emission on melting efficiency in selective laser melting

A wide proportion of the industrial Selective Laser Melting (SLM) systems are operated with high brilliance fiber laser sources. These sources are most commonly operated in continuous wave (CW). A smaller fraction of these systems employs pulsed wave (PW) emission by power modulation, resulting in pulses with μs level durations, kHz level repetition rates and comparable peak powers to CW emission. Clearly, the laser temporal emission mode can have an impact over temperature fields, which in return control the melt pool size, stability and densification behaviour. The aim of this paper is to investigate the effect of laser emission regime on the melting efficiency in SLM. In particular, an analytical model was developed to investigate the process efficiency in single track formation at fixed energy input when employing different emission modes. A single mode fiber laser installed on an in-house developed prototype powder bed fusion system was used as the experimental setup with AISI 316 L metallic powders. The effect of duty cycle was evaluated starting from CW (i.e. 100% duty) moving towards PW, at fixed energy density levels. Results show that at constant energetic input, CW increases process melting efficiency up to 3 times whilst the deposition stability is reduced with lower duty in PW regime. Although less efficient, at stable conditions the use of modulated emission produces narrower tracks providing higher process resolution.

Snapping of bistable, prestressed cylindrical shells

Bistable shells can reversibly change between two stable configurations with very little energetic input. Understanding what governs the shape and snap-through criteria of these structures is crucial for designing devices that utilize instability for functionality. Bistable cylindrical shells fabricated by stretching and bonding multiple layers of elastic plates will contain residual stress that will impact the shell's shape and the magnitude of stimulus necessary to induce snapping. Using the framework of incompatible elasticity, we first predict the mean curvature of a nearly cylindrical shell formed by arbitrarily prestretching one layer of a bilayer plate with respect to another. Then, beginning with a residually stressed cylinder, we determine the amount of the stimuli needed to trigger the snapping between two configurations through a combination of numerical simulations and theory. We demonstrate the role of prestress on the snap-through criteria, and highlight the important role that the Gaussian curvature in the boundary layer of the shell plays in dictating shell stability.

Entropy and the conceit of biodiversity management

AbstractMany conservation biologists and ecologists consider invasive species to be one of the greatest threats to biodiversity because their spread across biogeographical boundaries may endanger unique and localized expressions of biodiversity (whether species or communities). Consequently, they imagine a future, the ‘Homogocene’, in which a small set of species dominates ecosystems around the world, and they promote policies and practices to lessen the spread of these species. Here, we consider some thermodynamic dimensions of the efforts to maintain current biogeographical boundaries. We wish to explore an important conceptual analogy between thermodynamically‐closed systems and isolated biogeographical regions in ecology. The conceptual tools developed in the context of thermodynamic systems can be shown to have relevance in a wide variety of systems contexts. The ‘Maxwell's demon’ thought experiment suggests that entropy is best thought of as information‐relative rather than a ‘law of nature’. Adopting this Maxwellian thermodynamic approach to managing complexity can shed new light on the challenges of biodiversity management. To prevent the dispersion of invasive species, people must invest energy on a scale to counteract global trade and concomitant dispersal of species. We show that removing barriers to species interaction through globalization is akin to allowing a previously isolated thermal system to interact with its environment; in both cases, the system will tend towards mixing or ‘equilibrium’, and fighting this tendency is costly. Unless social and economic integration declines, the energetic input required to lessen the spread of invasive species will continue to grow.

Diffusion-advection within dynamic biological gaps driven by structural motion.

To study the significance of advection in the transport of solutes, or particles, within thin biological gaps (channels), we examine theoretically the process driven by stochastic fluid flow caused by random thermal structural motion, and we compare it with transport via diffusion. The model geometry chosen resembles the synaptic cleft; this choice is motivated by the cleft's readily modeled structure, which allows for well-defined mechanical and physical features that control the advection process. Our analysis defines a Péclet-like number, A^{D}, that quantifies the ratio of time scales of advection versus diffusion. Another parameter, A^{M}, is also defined by the analysis that quantifies the full potential extent of advection in the absence of diffusion. These parameters provide a clear and compact description of the interplay among the well-defined structural, geometric, and physical properties vis-a[over ̀]-vis the advection versus diffusion process. For example, it is found that A^{D}∼1/R^{2}, where R is the cleft diameter and hence diffusion distance. This curious, and perhaps unexpected, result follows from the dependence of structural motion that drives fluid flow on R. A^{M}, on the other hand, is directly related (essentially proportional to) the energetic input into structural motion, and thereby to fluid flow, as well as to the mechanical stiffness of the cleftlike structure. Our model analysis thus provides unambiguous insight into the prospect of competition of advection versus diffusion within biological gaplike structures. The importance of the random, versus a regular, nature of structural motion and of the resulting transient nature of advection under random motion is made clear in our analysis. Further, by quantifying the effects of geometric and physical properties on the competition between advection and diffusion, our results clearly demonstrate the important role that metabolic energy (ATP) plays in this competitive process.

Calculation and analysis of efficiencies and annual performances of Power-to-Gas systems

This paper describes a generic and systematic method to calculate the efficiency and the annual performance for Power-to-Gas (PtG) systems. This approach gives the basis to analytically compare different PtG systems using different technologies under different boundary conditions. To have a comparable basis for efficiency calculations, a structured break down of the PtG system is done. Until now, there has not been a universal approach for efficiency calculations. This has resulted in a wide variety of efficiency calculations used in feasibility studies and for business-case calculations. For this, the PtG system is divided in two sub-systems: the electrolysis and the methanation. Each of the two sub-systems consists of several subsystem boundary levels. Staring from the main unit, i.e. the electrolysis stack and/or methanation reactor, further units that are required to operate complete PtG system are considered with their respective subsystem boundary conditions.The paper provides formulas how the efficiency of each level can be calculated and how efficiency deviations can be integrated which are caused by the extended energy flow calculations to and from energy users and thermal losses. By this, a sensitivity analysis of the sub-systems can be gained and comprehensive goal functions for optimizations can be defined.In a second step the annual performance of the system is calculated as the ratio of useable output and energetic input over one year. The input is the integral of the annual need of electrical and thermal energy of a PtG system, depending on the different operation states of the plant. The output is the higher heating value of the produced gas and – if applicable – heat flows that are used externally.The annual performance not only evaluates the steady-state operating efficiency under full load, but also other states of the system such as cold standby or service intervals. It is shown that for a full system operation assessment and further system concept development, the annual performance is of much higher importance than the steady-state system efficiency which is usually referred to.In a final step load profiles are defined and the annual performance is calculated for a specific system configuration. Using this example, different operation strategies are compared.

Control over multiple molecular states with directional changes driven by molecular recognition

Recently, ligand–metal coordination, stimuli-responsive covalent bonds, and mechanically interlinked molecular constructs have been used to create systems with a large number of accessible structural states. However, accessing a multiplicity of states in sequence from more than one direction and doing so without the need for external energetic inputs remain as unmet challenges, as does the use of relatively weak noncovalent interactions to stabilize the underlying forms. Here we report a system based on a bispyridine-substituted calix[4]pyrrole that allows access to six different discrete states with directional control via the combined use of metal-based self-assembly and molecular recognition. Switching can be induced by the selective addition or removal of appropriately chosen ionic guests. No light or redox changes are required. The tunable nature of the system has been established through a combination of spectroscopic techniques and single crystal X-ray diffraction analyses. The findings illustrate a new approach to creating information-rich functional materials.

How temperature influences the viscosity of hornworm hemolymph.

Hemolymph is responsible for the transport of nutrients and metabolic waste within the insect circulatory system. Circulation of hemolymph is governed by viscosity, a physical property, which is well known to be influenced by temperature. However, the effect of temperature on hemolymph viscosity is unknown. We used Manduca sexta larvae to measure hemolymph viscosity across a range of physiologically relevant temperatures. Measurements were taken from 0 to 45°C using a cone and plate viscometer in a sealed environmental chamber. Hemolymph viscosity decreased with increasing temperature, showing a 6.4-fold change (11.08 to 1.74 cP) across the temperature range. Viscosity values exhibited two behaviors, changing rapidly from 0 to 15°C and slowly from 17.5 to 45°C. To test the effects of large particulates (e.g. cells) on viscosity, we also tested hemolymph plasma alone. Plasma viscosity also decreased as temperature increased, but did not exhibit two slope regimes, suggesting that particulates strongly influence low-temperature shifts in viscosity values. These results suggest that as environmental temperatures decrease, insects experience dramatic changes in hemolymph viscosity, leading to altered circulatory flows or increased energetic input to maintain similar flows. Such physical effects represent a previously unrecognized factor in the thermal biology of insects.

In vitro prediction of polycyclic aromatic hydrocarbon bioavailability of 14 different incidentally ingested soils in juvenile swine

Predicting mammalian bioavailability of PAH mixtures from in vitro bioaccessibility results has proven to be an elusive goal. In an attempt to improve in vitro predictions of PAH soil bioavailability we investigated how energetic input influences PAH bioaccessibility by using a high and low energetic shaking method. Co-inertia analysis (COIA), and Structural Equation Modeling (SEM) were also used to examine PAH-PAH interactions during ingestion. PAH bioaccessibility was determined from 14 historically contaminated soils using the fed organic estimation of the human simulation test (FOREhST) with inclusion of a silicone rod as a sorption sink and compared to bioavailability estimates from the juvenile swine model. Shaking method significantly affected PAH bioaccessibility in the FOREhST model, with PAH desorption from the high energy FOREhST almost an order of magnitude greater compared to the low energy FOREhST. PAH-PAH interactions significantly influenced PAH bioavailability and when these interactions were used in a linear model, the model predicted benzo(a)anthracene bioavailability with an slope of 1 and r2 of 0.66 and for benzo(a)pyrene bioavailability has a slope of 1 and r2 of 0.65. Lastly, to confirm the effects as determined by COIA and SEM, we spiked low levels of benzo(a)anthracene into historically contaminated soils, and observed a significant increase in benzo(a)pyrene bioaccessibility. By accounting for PAH interactions, and reducing the energetics of in vitro extractions, we were able to use bioaccessibility to predict bioavailability across 14 historically contaminated soils. Our work suggests that future work on PAH bioavailability and bioaccessibility should focus on the dynamics of how the matrix of PAHs present in the soil interact with mammalian systems. Such interactions should not only include the chemical interactions discussed here but also the interactions of PAH mixtures with mammalian uptake systems.

Energy performance of a new biomass harvester for recovery of orchard wood wastes as alternative to mulching

Abstract Woody crops such as orchards and olive groves require annual pruning operations, which leave abundant residues on the ground. These must be removed both for disease control and for facilitating the following tending activities. The resulting biomass can be managed as a waste or a by-product, in both cases incurring in a cost for farmers. A harvester prototype for collecting and comminuting apple pruning residues was tested and compared to a traditional mulcher. In particular, the study aimed at: 1) quantifying productivity and costs of the two systems, 2) evaluating the possible influence of apple variety, tree age and machine type on the productivity per hectare, and 3) estimating and comparing the energy balance of the two working options. The mulcher achieved a productivity of 0.41 ha SMH−1 against an average 0.27 ha SMH−1 of the harvester. Age of trees significantly influenced the productivity of both machines, with operative speed 42% higher in younger plantations. The cost of the operation added up to 137.5 € ha−1 and 275.2 € ha−1, respectively for the mulcher and the harvester. But the latter also produced 0.77 t dry matter ha−1 of biomass fuel suitable for in-farm use, whose value can cover most or the total of harvest costs. Accordingly, the energetic inputs amounted to 0.59 GJ ha−1 and 1.06 GJ ha−1 respectively for the mulcher and the harvester, while the recovered biomass provided an output of 6.30 GJ ha−1 for the latter system, resulting in a positive energy ratio (5:1).

Global rainfall erosivity assessment based on high-temporal resolution rainfall records

The exposure of the Earth’s surface to the energetic input of rainfall is one of the key factors controlling water erosion. While water erosion is identified as the most serious cause of soil degradation globally, global patterns of rainfall erosivity remain poorly quantified and estimates have large uncertainties. This hampers the implementation of effective soil degradation mitigation and restoration strategies. Quantifying rainfall erosivity is challenging as it requires high temporal resolution(<30 min) and high fidelity rainfall recordings. We present the results of an extensive global data collection effort whereby we estimated rainfall erosivity for 3,625 stations covering 63 countries. This first ever Global Rainfall Erosivity Database was used to develop a global erosivity map at 30 arc-seconds(~1 km) based on a Gaussian Process Regression(GPR). Globally, the mean rainfall erosivity was estimated to be 2,190 MJ mm ha−1 h−1 yr−1, with the highest values in South America and the Caribbean countries, Central east Africa and South east Asia. The lowest values are mainly found in Canada, the Russian Federation, Northern Europe, Northern Africa and the Middle East. The tropical climate zone has the highest mean rainfall erosivity followed by the temperate whereas the lowest mean was estimated in the cold climate zone.

Contributions of feather microstructure to eider down insulation properties

Insulation is an essential component of nest structure that helps provide incubation requirements for birds. Many species of waterfowl breed in high latitudes where rapid heat loss can necessitate a high energetic input from parents and use down feathers to line their nests. Common eider Somateria mollissima nest down has exceptional insulating properties but the microstructural mechanisms behind the feather properties have not been thoroughly examined.Here, we hypothesized that insulating properties of nest down are correlated to down feather (plumule) microstructure. We tested the thermal efficiency (fill power) and cohesion of plumules from nests of two Icelandic colonies of wild common eiders and compared them to properties of plumules of wild greylag goose Anser anser. We then used electron microscopy to examine the morphological basis of feather insulating properties. We found that greylag goose down has higher fill power (i.e. traps more air) but much lower cohesion (i.e. less prone to stick together) compared to common eider down. These differences were related to interspecific variation in feather microstructure. Down cohesion increased with the number of barbule microstructures (prongs) that create strong points of contact among feathers. Eider down feathers also had longer barbules than greylag goose down feathers, likely increasing their air‐trapping capacity. Feather properties of these two species might reflect the demands of their contrasting evolutionary history. In greylag goose, a temperate, terrestrial species, plumule microstructure may optimize heat trapping. In common eiders, a diving duck that nests in arctic and subarctic waters, plumule structure may have evolved to maximize cohesion over thermal insulation, which would both reduce buoyancy during their foraging dives and enable nest down to withstand strong arctic winds.