Seafloor primary production in a changing Arctic Ocean.

Phytoplankton and sea ice algae are traditionally considered to be the main primary producers in the Arctic Ocean. In this Perspective, we explore the importance of benthic primary producers (BPPs) encompassing microalgae, macroalgae, and seagrasses, which represent a poorly quantified source of Arctic marine primary production. Despite scarce observations, models predict that BPPs are widespread, colonizing ~3 million km2 of the extensive Arctic coastal and shelf seas. Using a synthesis of published data and a novel model, we estimate that BPPs currently contribute ~77 Tg C y-1 of primary production to the Arctic, equivalent to ~20 to 35% of annual phytoplankton production. Macroalgae contribute ~43 Tg C y-1, seagrasses contribute ~23 Tg C y-1, and microalgae-dominated shelf habitats contribute ~11 to 16 Tg C y-1. Since 2003, the Arctic seafloor area exposed to sunlight has increased by ~47,000 km2 y-1, expanding the realm of BPPs in a warming Arctic. Increased macrophyte abundance and productivity is expected along Arctic coastlines with continued ocean warming and sea ice loss. However, microalgal benthic primary production has increased in only a few shelf regions despite substantial sea ice loss over the past 20 y, as higher solar irradiance in the ice-free ocean is counterbalanced by reduced water transparency. This suggests complex impacts of climate change on Arctic light availability and marine primary production. Despite significant knowledge gaps on Arctic BPPs, their widespread presence and obvious contribution to coastal and shelf ecosystem production call for further investigation and for their inclusion in Arctic ecosystem models and carbon budgets.

Practical Guide to Measuring Wetland Carbon Pools and Fluxes.

Wetlands cover a small portion of the world, but have disproportionate influence on global carbon (C) sequestration, carbon dioxide and methane emissions, and aquatic C fluxes. However, the underlying biogeochemical processes that affect wetland C pools and fluxes are complex and dynamic, making measurements of wetland C challenging. Over decades of research, many observational, experimental, and analytical approaches have been developed to understand and quantify pools and fluxes of wetland C. Sampling approaches range in their representation of wetland C from short to long timeframes and local to landscape spatial scales. This review summarizes common and cutting-edge methodological approaches for quantifying wetland C pools and fluxes. We first define each of the major C pools and fluxes and provide rationale for their importance to wetland C dynamics. For each approach, we clarify what component of wetland C is measured and its spatial and temporal representativeness and constraints. We describe practical considerations for each approach, such as where and when an approach is typically used, who can conduct the measurements (expertise, training requirements), and how approaches are conducted, including considerations on equipment complexity and costs. Finally, we review key covariates and ancillary measurements that enhance the interpretation of findings and facilitate model development. The protocols that we describe to measure soil, water, vegetation, and gases are also relevant for related disciplines such as ecology. Improved quality and consistency of data collection and reporting across studies will help reduce global uncertainties and develop management strategies to use wetlands as nature-based climate solutions. Supplementary Information: The online version contains supplementary material available at 10.1007/s13157-023-01722-2.

MAKING WAVES: Effluent to estuary: Does sunshine or shade reduce downstream footprints of cities?

Riparian tree canopies are key components of river systems, and influence the provision of many essential ecosystem services. Their management provides the potential for substantial control of the downstream persistence of pollutants. The recent advent of new advances in mass spectrometry to detect a large suite of emerging contaminants, high-frequency observations of water quality and gas exchange (e.g., aquatic eddy covariance), and improved spatial resolution in remote sensing (e.g., hyperspectral measurements and high-resolution imagery), presents new opportunities to understand and more comprehensively quantify the role of riparian canopies as Nature-based Solutions. The paper outlines how we may now couple these advances in observational technologies with developments in water quality modelling to integrate simulation of eutrophication impacts with organic matter dynamics and fate of synthetic toxic compounds. In particular regarding solar radiation drivers, this enables us to scale-up new knowledge of canopy-mediated photodegradation processes at a basin level, and integrate it with ongoing improvements in understanding of thermal control, eutrophication, and ecosystem metabolism.

Preventing the next fragility fracture: a cross-sectional survey of secondary fragility fracture prevention services worldwide.

BACKGROUND: There has been an increasing awareness of the public health impact of fragility fractures due to osteoporosis and the imperative of addressing this health burden with well-designed secondary fragility fracture prevention services (SFFPS). The objectives of this survey, conducted within the international membership of the Fragility Fracture Network (FFN), were to identify gaps in services and identify the needs for further training and mentorship to improve the quality of SFFPS provided to patients who sustain fragility fractures. METHODS: We conducted an electronic cross-sectional survey of FFN Secondary Fracture Prevention Special Interest Group (SIG) members from April 2021 to June 2021 using SurveyMonkey. The survey questions were developed by four SIG members from New Zealand, Australia, Canada and the Netherlands, who have experience in developing, implementing and evaluating SFFPS. The sampling framework was convenience sampling of all 1162 registered FFN Secondary Fracture Prevention SIG members. Descriptive analyses were performed for all variables and presented as frequencies and percentages. RESULTS: 69 individuals participated in the survey, from 34 different countries over six continents, with a response rate of 6% (69/1162). Almost one-third of respondents (22/69) were from 15 countries within the European continent. Key findings included: (1) 25% of SFFPS only included patients with hip fracture; (2) less than 5% of SFFPS had any mandatory core competencies for training; (3) 38.7% of SFFPS were required to collect key performance indicators; and (4) 9% were collecting patient-reported outcome measures. CONCLUSIONS: This survey identified key areas for improving SFFPS, including: expanding the reach of SFFPS to more patients with fragility fracture, developing international core competencies for health provider training, using key performance indicators to improve SFFPS and including the patient voice in SFFPS development. These findings will be used by the FFN to support SFFPS development internationally.

Comment on "Breakdown of electroneutrality in nanopores".

Levy et al. [1] reported the breakdown of electroneutrality in confined nanopores embedded in a dielectric medium. A Robin boundary condition was derived which eliminates the need to include the dielectric medium explicitly when solving for the electric field within the nanopore. In this comment, we point out issues related to the approximations made during the derivation of the boundary condition. The errors caused by the use of this boundary condition can be significant even for nanochannels of large aspect (length to radius) ratio, a condition on which the approximations in Levy et al. [1] are based.

The nanofluidic capacitor: Differential capacitance in the absence of reservoirs.

Within the framework of the classical, mean-field Poisson-Boltzmann (PB) theory, we carry out direct numerical simulations to determine the differential capacitance of a closed nanochannel of a circular cross section, embedded in a polymeric host with charged walls and sealed at both ends by metal electrodes under an external potential bias. Our approach employs the modified PB equation, which accounts for the finite size of ions and the dependency of the electrolyte's relative permittivity on the local electric field. In view of the absence of reservoirs, the modified PB equation becomes subject to global algebraic constraints, without prior knowledge of a bulk electrolyte concentration. Equilibrium ion distributions and differential capacitance curves are investigated as functions of electrolyte properties and the surface charge density modulation. This modulation leads to asymmetric differential capacitance curves that can be tuned. More generally, our approach provides a transparent numerical framework for accurately simulating confined nanofluidic systems with new physical properties that may be exploited in novel iontronic circuit elements.

Forest edge effects on moss growth are amplified by drought.

Forest fragmentation increases the amount of edges in the landscape. Differences in wind, radiation, and vegetation structure create edge-to-interior gradients in forest microclimate, and these gradients are likely to be more pronounced during droughts and heatwaves. Although the effects of climate extremes on edge influences have potentially strong and long-lasting impacts on forest understory biodiversity, they are not well understood and are not often considered in management and landscape planning. Here we used a novel method of retrospectively quantifying growth to assess biologically relevant edge influences likely caused by microclimate using Hylocomium splendens, a moss with annual segments. We examined how spatio-temporal variation in drought across 3 years and 46 sites in central Sweden, affected the depth and magnitude of edge influences. We also investigated whether edge effects during drought were influenced by differences in forest structure. Edge effects were almost twice as strong in the drought year compared to the non-drought years, but we did not find clear evidence that they penetrated deeper into the forest in the drought year. Edge influences were also greater in areas that had fewer days with rain during the drought year. Higher levels of forest canopy cover and tree height buffered the magnitude of edge influence in times of drought. Our results demonstrate that edge effects are amplified by drought, suggesting that fragmentation effects are aggravated when droughts become more frequent and severe. Our results suggest that dense edges and buffer zones with high canopy cover can be important ways to mitigate negative drought impacts in forest edges.

Interactive effects of drought and edge exposure on old-growth forest understory species.

Context: Both climatic extremes and land-use change constitute severe threats to biodiversity, but their interactive effects remain poorly understood. In forest ecosystems, the effects of climatic extremes can be exacerbated at forest edges. Objectives: We explored the hypothesis that an extreme summer drought reduced the richness and coverage of old-growth forest species, particularly in forest patches with high edge exposure. Methods: Using a high-resolution spatially explicit precipitation dataset, we could detect variability in drought intensity during the summer drought of 2018. We selected 60 old-growth boreal forest patches in central Sweden that differed in their level of drought intensity and amount of edge exposure. The year after the drought, we surveyed red-listed and old-growth forest indicator species of vascular plants, lichens and bryophytes. We assessed if species richness, composition, and coverage were related to drought intensity, edge exposure, and their interaction. Results: Species richness was negatively related to drought intensity in forest patches with a high edge exposure, but not in patches with less edge exposure. Patterns differed among organism groups and were strongest for cyanolichens, epiphytes associated with high-pH bark, and species occurring on convex substrates such as trees and logs. Conclusions: Our results show that the effects of an extreme climatic event on forest species can vary strongly across a landscape. Edge exposed old-growth forest patches are more at risk under extreme climatic events than those in continuous forests. This suggest that maintaining buffer zones around forest patches with high conservation values should be an important conservation measure. Supplementary information: The online version contains supplementary material available at 10.1007/s10980-022-01441-9.

Room temperature synthesis of perylene diimides facilitated by high amic acid solubility.

A novel protocol for the synthesis of perylene diimides (PDIs), by reacting perylene dianhydride (PDA) with aliphatic amines is reported. Full conversions were obtained at temperatures between 20 and 60 °C, using DBU as the base in DMF or DMSO. A "green" synthesis of PDIs, that runs at higher temperatures, was developed using K2CO3 in DMSO. The reaction sequence for the imidization process, via perylene amic acid intermediates (PAAs), has been confirmed experimentally aided by the synthesis and full characterization of stable model amic acid salts and amic esters. Kinetic studies, using absorption spectroscopy, have established that PDI formation proceeds via fast amic acid formation, followed by a slow conversion to imides. Solubility of the intermediate PAA salts is found to be low and rate-limiting. Based on this finding, quantitative PDI synthesis at room temperature was achieved by diluting the reaction mixture with water, the solvent in which PAA salts have better solubility. Thus, the otherwise harsh synthesis of PDIs has been transformed into an extremely convenient functional group tolerant and highly efficient reaction that runs at room temperature.

Aquatic Eddy Covariance: The Method and Its Contributions to Defining Oxygen and Carbon Fluxes in Marine Environments.

Aquatic eddy covariance (AEC) is increasingly being used to study benthic oxygen (O2) flux dynamics, organic carbon cycling, and ecosystem health in marine and freshwater environments. Because it is a noninvasive technique, has a high temporal resolution (∼15 min), and integrates over a large area of the seafloor (typically 10-100 m2), it has provided new insights on the functioning of aquatic ecosystems under naturally varying in situ conditions and has given us more accurate assessments of their metabolism. In this review, we summarize biogeochemical, ecological, and biological insightsgained from AEC studies of marine ecosystems. A general finding for all substrates is that benthic O2 exchange is far more dynamic than earlier recognized, and thus accurate mean values can only be obtained from measurements that integrate over all timescales that affect the local O2 exchange. Finally, we highlight new developments of the technique, including measurements of air-water gas exchange and long-term deployments.

Covid-19 given opportunity to use ultrasound in the plaster room to continue secondary fracture prevention care: A retrospective Fracture Liaison Service study.

INTRODUCTION: Fracture Liaison Service (FLS) managed secondary fracture prevention services have been hampered during the COVID-19 pandemic. A challenging opportunity is to use pulse-echo ultrasound (P-EU) in the plaster room. The study had two objectives: can P-EU help our decision to justly avoid DXA/VFA scans in plaster treated women (50-70 years) after fracture and whether its use can encourage or nudge all plaster treated patients (>50 years) who need DXA/VFA scans. PATIENTS AND METHODS: 1307 patients (cohort: pre-COVID-19) and 1056 patients (cohort: peri-COVID-19), each of them ≥ 50 years after recent fracture, were studied. Only in women aged 50-70 years, we used a P-EU decision threshold (DI) >= 0.896 g/cm2 to rule out further analysis by means of DXA/VFA. All other plaster patients received P-EU as part of patient information. Peri-Covid-19, all performed DXA/VFA scans were counted until three months post-study closure. By then each patient still waiting for a DXA/VFA had received a scan. RESULTS: Peri-COVID-19, 69 out of 191 plaster-treated women aged 50-70 years were ruled out (36%), for plaster and not in-plaster treated women aged 50-70 years, it was 27%. Comparing all peri-to pre-COVID-19 plaster-treated women and men, a significant P-EU nudging effect was found (difference in proportions: 8.8%) P = .001. CONCLUSION: The combination of patient information and P-EU in the plaster room is effective to reduce DXA/VFA scans and allow extra patients to undergo DXA/VFA. After all, more than a quarter of 50-70 years old women in plaster did not need to be scanned.

Multi-loop atomic Sagnac interferometry.

The sensitivity of light and matter-wave interferometers to rotations is based on the Sagnac effect and increases with the area enclosed by the interferometer. In the case of light, the latter can be enlarged by forming multiple fibre loops, whereas the equivalent for matter-wave interferometers remains an experimental challenge. We present a concept for a multi-loop atom interferometer with a scalable area formed by light pulses. Our method will offer sensitivities as high as [Formula: see text] rad/s at 1 s in combination with the respective long-term stability as required for Earth rotation monitoring.

Random pore-network model for polymer electrolyte membranes.

A random pore-network model for polymer electrolyte membranes (PEM) is presented that couples the flow of protons and water through cylindrical channels to the swelling of the membrane. While the flows are determined by closed-form solutions of the Poisson-Nernst-Planck-Stokes equations, the fluid-structure interaction is described by a pressure balance at the channel walls. Macroscopic membrane properties, such as the conductivity, permeability and electro-osmotic coefficient, are computed and compared to experimental data in the literature. In light of the model simplifications, the results compare favourably to data but they also point to the importance of describing proton diffusion in PEM nanopores accurately.

Towards advancing scientific knowledge of climate change impacts on short-duration rainfall extremes.

A large number of recent studies have aimed at understanding short-duration rainfall extremes, due to their impacts on flash floods, landslides and debris flows and potential for these to worsen with global warming. This has been led in a concerted international effort by the INTENSE Crosscutting Project of the GEWEX (Global Energy and Water Exchanges) Hydroclimatology Panel. Here, we summarize the main findings so far and suggest future directions for research, including: the benefits of convection-permitting climate modelling; towards understanding mechanisms of change; the usefulness of temperature-scaling relations; towards detecting and attributing extreme rainfall change; and the need for international coordination and collaboration. Evidence suggests that the intensity of long-duration (1 day+) heavy precipitation increases with climate warming close to the Clausius-Clapeyron (CC) rate (6-7% K-1), although large-scale circulation changes affect this response regionally. However, rare events can scale at higher rates, and localized heavy short-duration (hourly and sub-hourly) intensities can respond more strongly (e.g. 2 × CC instead of CC). Day-to-day scaling of short-duration intensities supports a higher scaling, with mechanisms proposed for this related to local-scale dynamics of convective storms, but its relevance to climate change is not clear. Uncertainty in changes to precipitation extremes remains and is influenced by many factors, including large-scale circulation, convective storm dynamics andstratification. Despite this, recent research has increased confidence in both the detectability and understanding of changes in various aspects of intense short-duration rainfall. To make further progress, the international coordination of datasets, model experiments and evaluations will be required, with consistent and standardized comparison methods and metrics, and recommendations are made for these frameworks. This article is part of a discussion meeting issue 'Intensification of short-duration rainfall extremes and implications for flash flood risks'.

Osteoporosis care during the COVID-19 pandemic in the Netherlands: A national survey.

This is a survey study concerning osteoporosis care during the COVID-19 pandemic in the Netherlands. Respondents reported that osteoporosis care stagnated and lower quality of care was provided. This leads to the conclusion that standardization of osteoporosis care delivery in situations of crisis is needed. PURPOSE: During the initial phase of the COVID-19 pandemic, there was no guidance of professional societies or guidelines on the organization of osteoporosis care in case of such a crisis, and treatment relied on local ad hoc strategies. Experiences from the current pandemic need to be taken into account for the near future, and therefore, a national multidisciplinary survey was carried out in the Netherlands. METHODS: A survey of 17 questions concerning the continuation of bone mineral density measurements by Dual Energy X-ray absorptiometry (DXA), outpatient clinic visits, and prescription of medication was sent to physicians, nurses, nurse practitioners, and physician assistants working in the field of osteoporosis. RESULTS: 77 respondents finished the questionnaire, of whom 39 (50.6%) reported a decline in DXA-scanning and 36 (46.8%) no scanning at all during the pandemic. There was an increase in remote consultations for both new and control patient visits (n = 48, 62.3%; n = 62, 81.7% respectively). Lower quality of care regarding fracture prevention was reported by more than half of the respondents (n = 44, 57.1%). Treatment with intravenous bisphosphonates and denosumab was delayed according to 35 (45.4%) and 6 (6.3%) of the respondents, respectively. CONCLUSION: During the COVID-19 pandemic, osteoporosis care almost completely arrested, especially because of the discontinuation of DXA-scanning and closing of outpatient clinics. More than half of the respondents reported a substantial lower quality of osteoporosis care during the COVID pandemic. To prevent an increase in fracture rates and a decrease in patient motivation, adherence and satisfaction, standardization of osteoporosis care delivery in situations of crisis is needed.

The greenhouse gas offset potential from seagrass restoration.

Awarding CO2 offset credits may incentivize seagrass restoration projects and help reverse greenhouse gas (GHG) emissions from global seagrass loss. However, no study has quantified net GHG removal from the atmosphere from a seagrass restoration project, which would require coupled Corg stock and GHG flux enhancement measurements, or determined whether the creditable offset benefit can finance the restoration. We measured all of the necessary GHG accounting parameters in the 7-km2 Zostera marina (eelgrass) meadow in Virginia, U.S.A., part of the largest, most cost-effective meadow restoration to date, to provide the first seagrass offset finance test-of-concept. Restoring seagrass removed 9,600 tCO2 from the atmosphere over 15 years but also enhanced both CH4 and N2O production, releasing 950 tCO2e. Despite tripling the N2O flux to 0.06 g m-2 yr-1 and increasing CH4 8-fold to 0.8 g m-2 yr-1, the meadow now offsets 0.42 tCO2e ha-1 yr-1, which is roughly equivalent to the seagrass sequestration rate for GHG inventory accounting but lower than the rates for temperate and tropical forests. The financial benefit for this highly successful project, $87 K at $10 MtCO2e-1, defrays ~10% of the restoration cost. Managers should also consider seagrass co-benefits, which provide additional incentives for seagrass restoration.

The use of pulse-echo ultrasound in women with a recent non-vertebral fracture to identify those without osteoporosis and/or a subclinical vertebral fracture: a pilot study.

A pilot study on the use of P-EU to identify patients without osteoporosis and/or a subclinical vertebral fracture after a recently sustained non-vertebral fracture (NVF). INTRODUCTION: Screening with portable devices at emergency departments or plaster rooms could be of interest to limit referrals for dual X-ray absorptiometry (DXA) and vertebral fracture assessment (VFA). We calculated the number of negative tests for osteoporosis and/or subclinical vertebral fractures (VFs) using pulse-echo ultrasonometry (P-UE) at different thresholds. PATIENTS AND METHODS: In this cross-sectional study, 209 consecutive women of 50-70 years with a recent non-vertebral fracture (NVF) were studied at the Fracture Liaison Service (FLS) of one hospital. All women received DXA/VFA and P-EU (Bindex®) assessments. Various P-EU thresholds (based on the density index (DI, g/cm2)) were analyzed to calculate the best balance between true negative (indeed no osteoporosis and/or subclinical VF) and false negative tests (osteoporosis and/or subclinical VF according to DXA/VFA). RESULTS: Eighty-three women had osteoporosis (40%) and 17 women at least one VF (8%). Applying the manufacturer's recommended P-EU threshold (DI 0.844 g/cm2) being their proposed cut-off for not having hip osteoporosis resulted in 77 negative tests (37%, 31% true negative and 6% false negative tests). A DI of 0.896 g/cm2 resulted in 40 negative tests (19.3%) (38 true negative (18.3%) and 2 false negative tests (1.0%)). CONCLUSION: The application of P-EU enables the identification of a substantial proportion of women with recent non-vertebral fractures at the FLS who would not need a DXA/VFA referral because they had no osteoporosis and/or subclinical vertebral fractures. The most conservative P-EU threshold resulted in 18.3% true negative tests verified by DXA/VFA against 1% false negative test results.

Asymmetric double-layer charging in a cylindrical nanopore under closed confinement.

This article presents a physical-mathematical treatment and numerical simulations of electric double layer charging in a closed, finite, and cylindrical nanopore of circular cross section, embedded in a polymeric host with charged walls and sealed at both ends by metal electrodes under an external voltage bias. Modified Poisson-Nernst-Planck equations were used to account for finite ion sizes, subject to an electroneutrality condition. The time evolution of the formation and relaxation of the double layers was explored. Moreover, equilibrium ion distributions and differential capacitance curves were investigated as functions of the pore surface charge density, electrolyte concentration, ion sizes, and pore size. Asymmetric properties of the differential capacitance curves reveal that the structure of the double layer near each electrode is controlled by the charge concentration along the pore surface and by charge asymmetry in the electrolyte. These results carry implications for accurately simulating cylindrical capacitors and electroactuators.

Ultrasonic Synthetic-Aperture Interface Imaging.

Synthetic-aperture (SA) imaging is a popular method to visualize the reflectivity of an object from ultrasonic reflections. The method yields an image of the (volume) contrast in acoustic impedance with respect to the embedding. Typically, constant mass density is assumed in the underlying derivation. Due to the band-limited nature of the recorded data, the image is blurred in space, which is quantified by the associated point spread function. SA volume imaging is valid under the Born approximation, where it is assumed that the contrast is weak. When objects are large with respect to the wavelength, it is questionable whether SA volume imaging should be the method-of-choice. Herein, we propose an alternative solution that we refer to as SA interface imaging. This approach yields a vector image of the discontinuities of acoustic impedance at the tissue interfaces. Constant wave speed is assumed in the underlying derivation. The image is blurred in space by a tensor, which we refer to as the interface spread function. SA interface imaging is valid under the Kirchhoff approximation, where it is assumed that the wavelength is small compared to the spatial dimensions of the interfaces. We compare the performance of volume and interface imaging on synthetic data and on experimental data of a gelatin cylinder with a radius of 75 wavelengths, submerged in water. As expected, the interface image peaks at the gelatin-water interface, while the volume image exposes a peak and trough on opposing sides of the interface.

Drone retinopathy.

PURPOSE: To report a case of solar retinopathy due to inadvertent exposure to the sun while piloting a drone without protective eyewear. METHODS: A 29-year-old male underwent a complete eye exam including optical coherence tomography (OCT) of the macula. RESULTS: Bilateral juxtafoveal outer retinal microcystic cavities present on OCT consistent with solar retinopathy. CONCLUSION: With the increasing popularity of unmanned aircrafts, eye protection awareness during drone use is essential.