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Background: Seafarers are at an increased risk of developing cardiovascular diseases (CVDs), potentially due to a stressful working environment and behavioral risk factors. To develop better prevention strategies, it is important to elucidate the extent of this risk. Therefore, we conducted a systematic literature review on CVD in seafarers. Method: We conducted systematic searches in five databases. All studies investigating CVDs among occupational seafarers, published in articles or conference papers, were eligible for inclusion. The identified records were screened and reviewed by two independent researchers, who also evaluated the methodological quality of the included studies. Results: Three thousand nine hundred and seventeen records qualified for screening, and 55 were eligible for inclusion. Most of the studies were observational, including cohort, frequency, incidence or prevalence studies, and review of case records. Around half were assessed at risk of biased findings. Participants in the studies were primarily from North America or the European continent and work onboard transportation vessels. Many studies investigated CVDs as a cause of death, focusing on conditions such as CVD, ischemic heart disease, and myocardial infarction. Frequency of CVD conditions varied but indicate that seafarers face a greater risk compared to the reference populations or control groups. Environmental factors were mainly investigated as risk factors. Conclusion: Our results indicate a higher risk of CVDs among seafarers compared to reference or control groups. However, due to the variable quality of the evidence, well‐designed studies are needed to establish the causes of cardiovascular mortality and morbidity in seafarers and to investigate behavioral aspects of cardiovascular risk. [ABSTRACT FROM AUTHOR]

In situ measurements of particulate inherent optical properties (IOPs) – absorption (ap(λ)), scattering (bp(λ)), and beam attenuation (cp(λ)) – are crucial for development of optical algorithms that retrieve biogeochemical quantities such as Chlorophyll a , particulate organic carbon (POC) and total suspended matter (TSM). Here we present a compilation of particulate absorption-attenuation spectrophotometric data measured underway on nine Atlantic Meridional Transect (AMT) cruises between 50° north to 50° south from 2009–2019. The compilation includes co-incident high performance liquid chromatography (HPLC) phytoplankton pigment concentrations, which are used to calibrate transects of Total Chlorophyll a (Tot_Chl_a) concentrations derived from the ap(λ) line-height method. The IOP data are processed using a consistent methodology, and include propagated uncertainties for each IOP variable, uncertainty quantification for the Tot_Chl_a concentrations based on HPLC match-ups, application of consistent set of quality-control filters, and standardisation of output data fields and formats. The total IOP dataset consists of ~310,000 measurements at a 1 minute binning (~270,000 hyper-spectral) and > 700 co-incident HPLC pigment surface samples (~600 of which are coincident with hyper-spectral IOPs). We present geographic variation in the IOPs, HPLC phytoplankton pigments, and the ap -derived Tot_Chl_a concentrations, which are shown to have uncertainties between 8–20 %. Additionally, to stimulate further investigation of accessory pigment extraction from ap(λ) , we quantify pigment correlation matrices and identify spectral characteristics of end-member ap(λ) spectra where accessory pigment groupings are present in higher concentrations relative to Tot_Chl_a. All data are made publicly available in SeaBASS and NetCDF formats via the following links: https://seabass.gsfc.nasa.gov/archive/PML/AMT , and https://doi.org/10.5281/zenodo.12527954. [ABSTRACT FROM AUTHOR]

Introduction: The use of patient-reported outcomes (PROs) has been shown to enhance the accuracy of symptom collection and improve overall survival and quality of life. This is the first study comparing concordance and patient preference for two PRO tools: Patient-Reported Outcomes version of the Common Terminology Criteria for Adverse Events (PRO-CTCAE®) and the adapted-REQUITE Lung Questionnaire. Materials and Methods: Patients with lung cancer were recruited to the study while attending outpatient clinics at a tertiary cancer centre. Clinician-reported outcomes were generated through initial patient assessment with CTCAE v4.03. Participants then completed the PRO-CTCAE® and adapted-REQUITE questionnaires. Concordance between the 2 questionnaires was assessed by calculating Pearson correlation coefficient. PRO-CTCAE® and CTCAE concordance was demonstrated by calculating Pearson correlation coefficient from the linear predictors of an ordinal logistic regression. P-values were also calculated. Results: Out of 74 patients approached, 65 provided written informed consent to participate in the study. 63 (96.9%) patients completed both PRO-CTCAE® and adapted-REQUITE questionnaires. Pearson correlation coefficient between PRO tools was 0.8-0.83 (p <.001). Correlation between CTCAE and PRO-CTCAE® ranged between 0.66-0.82 (p <.001). Adapted-REQUITE and CTCAE correlation was higher for all symptoms ranging between 0.79-0.91 (p <.001). Acceptable discrepancies within one grade were present in 96.8%-100% of symptom domains for REQUITE and in 92.1%-96.8%for all domains in the PRO-CTCAE®. 54% of the total participant cohort favored the adapted-REQUITE questionnaire due to reduced subjectivity in the questions and ease of use. Conclusion: The adapted-REQUITE questionnaire has shown a superior correlation to clinician-reported outcomes and higher patient preference than the PRO-CTCAE®. The results of this study suggest the use of the REQUITE questionnaire for patients with lung cancer in routine clinical practice. [ABSTRACT FROM AUTHOR]

Copyright of Chemie Ingenieur Technik (CIT) is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chemie Ingenieur Technik (CIT) is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chemie Ingenieur Technik (CIT) is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

British systematics was distinctly marked by a raft of vituperative controversies around the turn of the 1830s. After the local collapse of broad consensus in the Linnaean system by 1820, the emergence of new schemes of classification—most notably, the "quinarian" system of William Sharp Macleay—brought with it an unprecedented register of public debate among zoologists in Britain, one which a young Charles Darwin would bitterly describe to his friend John Stevens Henslow in October 1836 as possessing a "mean quarrelsome spirit," conducted in "a manner anything but like that of gentlemen." This article aims to provide a social and conceptual account of the remarkable tenor of zoological discourse in Britain in the late 1820s and early 1830s, with joint attention to the philosophical and interpersonal commitments at play. In doing so, it analyzes the three of the period's most striking public controversies, each of which counted key advocates of the quinarian system as central participants. [ABSTRACT FROM AUTHOR]

The alignment of anisotropic nanoparticles in flow has been used for a range of applications such as the preparation of strong fibres and the assembly of in‐plane aligned 1D‐nanoobjects that are used for electronic devices, sensors, energy and biological application. Important is also the flow behaviour of nanoparticles that were designed for nanomedical applications such as drug delivery. It is widely observed that non‐spherical nanoparticles have longer circulation times and a more favourable biodistribution. To be able to understand this behaviour, researchers have turned to analyzing the flow of non‐spherical nanoparticles in the blood stream. In this review, an overview of microfluidic techniques that are used to monitor the alignment of anisotropic nanoparticles in solution will be provided, which includes analysis by small angle X‐ray scattering (SAXS) and polarized light microscopy. The flow of these nanoparticles in blood is then discussed as the presence of red blood cells causes margination of some nanoparticles. Using fluorescence microscopy, the extent of margination can be identified, which coincides with the ability of nanoparticles to adhere to the cells grown along the wall. While these studies are mainly carried out in vitro using blood, initial investigations in vivo were able to confirm the unusual flow of anisotropic nanoparticles. [ABSTRACT FROM AUTHOR]

Methane explosions are among the main hazards in coal mines. Shock waves from methane explosions can cause damage near the explosion site, and combustion products can spread along the tunnel to locations far from the explosion source and endanger the lives and health of personnel. Therefore, the study of the propagation patterns of methane explosion shock waves and the distribution of high-temperature combustion products in tunnels. has significance for emergency decision-making in the event of methane explosions in a mine. This study uses the 3D Computational Fluid Dynamics (CFD) program GASFLOW-MPI, which models the one-step methane combustion mechanism with the addition of a heat transfer model. The methane explosion process is simulated and reproduced at the Lake Lynn Experimental Mine (LLEM) to analyze the process of gas deflagration. The results reveal that the overpressure in the tunnel after the methane explosion oscillates and decays with time. Gaseous products of the explosion "expand and compress" and flow back and forth in accordance with the oscillation of overpressure. The maximum expansion ratio of the CO2 concentration isosurfaces of 0.5% in the heat transfer simulation is 6.21, whereas the volume expansion ratio is 3.78 once the flow field stabilizes. The distribution of combustion products along the alleyway exhibits a Gaussian decay trend. The range of gaseous product distribution and temperature fields in the adiabatic tunnel is significantly higher than that in the heat transfer simulations, thus indicating that heat loss significantly influences the temperature characteristics and distribution pattern of combustion products in the full-scale tunnel. [ABSTRACT FROM AUTHOR]

In situ hyperspectral remote-sensing reflectance ( R r s (λ) ) is used to derive water quality products and perform autonomous monitoring of aquatic ecosystems. Conventionally, above-water R r s (λ) is estimated from three spectroradiometers which measure downwelling planar irradiance ( E d (λ) ), sky radiance ( L s (λ) ), and total upwelling radiance ( L t (λ) ), with a scaling of L s (λ) / E d (λ) used to correct for surface-reflected radiance. Here, we incorporate direct and diffuse irradiance, ( E d d (λ) ) and E d s (λ) ), from a hyperspectral pyranometer (HSP) in an R r s (λ) processing algorithm from a solar-tracking radiometry platform (So-Rad). HSP measurements of sun and sky glint (scaled E d d (λ) / E d (λ) and E d s (λ) / E d (λ) ) replace model-optimized terms in the 3C (three-glint component) R r s (λ) algorithm, which estimates R r s (λ) via spectral optimization of modelled atmospheric and water properties with respect to measured radiometric quantities. We refer to the HSP-enabled method as DD (direct-diffuse) and compare differences in R r s (λ) and R r s (λ) variability (assessed over 20 min measurement cycles) between 3C and DD as a function of atmospheric optical state using data from three ports in the Western Channel. The greatest divergence between the algorithms occurs in the blue part of the spectrum where DD has significantly lower R r s (λ) variability than 3C in clearer sky conditions. We also consider R r s (λ ) processing from a hypothetical two-sensor configuration (using only the L t (λ) spectroradiometer and the HSP and referred to as DD2) as a potential lower-cost measurement solution, which is shown to have comparable R r s (λ ) and R r s (λ ) variability to DD in clearer sky conditions. Our results support that the HSP sensor can fulfil a dual role in aquatic ecosystem monitoring by improving precision in R r s (λ) alongside its primary function to characterize aerosols. [ABSTRACT FROM AUTHOR]

The main purpose of this article is to emphasize the importance of clarifying the probabilistic framework adopted for volcanic hazard and eruption forecasting. Eruption forecasting and volcanic hazard analysis seek to quantify the deep uncertainties that pervade the modeling of pre-, sin-, and post-eruptive processes. These uncertainties can be differentiated into three fundamental types: (1) the natural variability of volcanic systems, usually represented as stochastic processes with parameterized distributions (aleatory variability); (2) the uncertainty in our knowledge of how volcanic systems operate and evolve, often represented as subjective probabilities based on expert opinion (epistemic uncertainty); and (3) the possibility that our forecasts are wrong owing to behaviors of volcanic processes about which we are completely ignorant and, hence, cannot quantify in terms of probabilities (ontological error). Here we put forward a probabilistic framework for hazard analysis recently proposed by Marzocchi and Jordan (2014), which unifies the treatment of all three types of uncertainty. Within this framework, an eruption forecasting or a volcanic hazard model is said to be complete only if it (a) fully characterizes the epistemic uncertainties in the model's representation of aleatory variability and (b) can be unconditionally tested (in principle) against observations to identify ontological errors. Unconditional testability, which is the key to model validation, hinges on an experimental concept that characterizes hazard events in terms of exchangeable data sequences with well-defined frequencies. We illustrate the application of this unified probabilistic framework by describing experimental concepts for the forecasting of tephra fall from Campi Flegrei. Eventually, this example may serve as a guide for the application of the same probabilistic framework to other natural hazards. [ABSTRACT FROM AUTHOR]

The Amundsen Sea Embayment of the West Antarctic Ice Sheet contains Thwaites and Pine Island Glaciers, two of the most rapidly changing glaciers in Antarctica. To date, Pine Island and Thwaites Glaciers have only been observed by independent airborne radar sounding surveys, but a combined cross‐basin analysis that investigates the basal conditions across the Pine Island‐Thwaites Glaciers boundary has not been performed. Here, we combine two radar surveys and correct for their differences in system parameters to produce unified englacial attenuation and basal relative reflectivity maps spanning both Pine Island and Thwaites Glaciers. Relative reflectivities range from −24.8 to +37.4 dB with the highest values beneath fast‐flowing ice at the ice sheet margin. By comparing our reflectivity results with previously derived radar specularity and trailing bed echoes at Thwaites Glacier, we find a highly diverse subglacial landscape and hydrologic conditions that evolve along‐flow. Together, these findings highlight the potential for joint airborne radar analysis with ground‐based seismic and geomorphological observations to understand variations in the bed properties and cross‐catchment interactions of ice streams and outlet glaciers. Plain Language Summary: Pine Island Glacier (PIG) and Thwaites Glacier (TG) are the fastest‐changing outlet glaciers in West Antarctica. To understand how these glaciers move and evolve in the future, we need to understand processes that occur at the ice‐bed interface that control glacial motion. Here, we investigate the basal conditions of PIG and TG using radar sounding observations from two independent airborne surveys. By estimating the brightness and shape of radar power returns from the ice bed, we characterize the distribution of subglacial meltwater and how the subglacial landscape evolves along with ice flow. We also extend our radar interpretations using existing ground‐based seismic and geomorphology observations. These results show that PIG has a greater area of wet bed that extends far inland into the head of its ice tributaries. Meanwhile, TG has a patchier wet and locally frozen bed. Along the boundary of the two glaciers, we find that the presence of deformable sediments or subglacial meltwater, in addition to topography, also plays a role in explaining the present‐day configuration of ice flow. Future studies of ice sheet basal processes should more frequently combine airborne radar and ground‐based seismic and geomorphological observations to provide a unified interpretation. Key Points: We analyze two simultaneous 2004/2005 airborne radar surveys of Pine Island and Thwaites Glaciers conducted using different soundersWe produce catchment‐wide englacial attenuation and basal reflectivity maps for Pine Island and Thwaites GlaciersRadar analysis reveals a critical frozen basal patch that currently separates the two neighboring glaciers [ABSTRACT FROM AUTHOR]

Earthquake ruptures and seismic sequences can be very complex, involving slip in various directions on surfaces of variable orientation. How is this geometrical complexity in seismic energy release, here called mechanism complexity, governed by tectonic stress? We address this question using a probabilistic model for the distribution of double couples that is consistent with three assumptions commonly used in regional stress inversions: the tectonic stress is constant, slip vectors are aligned with the maximum shear traction in the plane of slip, and higher shear traction promotes more seismic energy release. We characterize the moment-tensor field of a stress-aligned source process in terms of an ordered set of principal-stress directions, a stress shape factor R , and a strain-sensitivity parameter |$\kappa $|⁠. The latter governs the dependence of the seismic moment density on the shear-traction magnitude and therefore parametrizes the seismic strain response to the driving stress. These stress–strain characterization (SSC) parameters can be determined from moment measures of mechanism complexity observed in large earthquakes and seismic sequences. The moment measures considered here are the ratio of the Aki moment to the total seismic moment and the five fractions of the total-moment defined by linear mappings of the moment-tensor field onto an orthonormal basis of five deviatoric mechanisms. We construct this basis to be stress-oriented by choosing its leading member to be the centroid moment tensor (CMT) mechanism and three others representing orthogonal rotations of the CMT mechanism. From the projections of the stress-aligned field onto this stress-oriented basis, we derive explicit expressions for the expected values of the moment-fraction integrals as functions of R and |$\kappa $|⁠. We apply the SSC methodology to a 39-yr focal mechanism catalogue of the San Jacinto Fault (SJF) zone and to realizations from the Graves–Pitarka stochastic rupture model. The SJF data are consistent with the SSC model, and the recovered parameters, |$R = {\rm{ }}0.45 \pm 0.050$| and |$\kappa = {\rm{ }}5.7 \pm 1.75$|⁠ , indicate moderate mechanism complexity. The parameters from the Graves–Pitarka realizations, |$R = {\rm{\ }}0.49 \pm 0.005,{\rm{\ \ }}\kappa = {\rm{\ }}9.5 \pm 0.375,$| imply lower mechanism complexity than the SJF catalogue, and their moment measures show inconsistencies with the SSC model that can be explained by differences in the modelling assumptions. [ABSTRACT FROM AUTHOR]

Englacial layer velocity can provide insights on the vertical-velocity structure of the ice sheets. We present a repeat-pass interferometric approach that allows the estimation of the vertical englacial layer velocity using the radar sounder data. In contrast to the ground-based sensors, the airborne radar sounder data can potentially be used to estimate the layer velocity on a continental scale. When merged with the horizontal surface velocity and the numerical models, layer velocity can support the 3-D analysis of the ice flow and structure. Our aim is to provide the proof-of-concept demonstration that, similar to the side-looking synthetic aperture radar for imaging, the airborne radar sounder data can be used to estimate the subwavelength displacement of the englacial radio-stratigraphic layers. To achieve this, we use the phase and magnitude acquired repeatedly over the same region of interest. After the extraction of the crossing points, two acquisitions are finely registered. Then, we compute the interferometric phase for the englacial layers (which are shown to behave as PSs in the nadir sounding geometry), to estimate a vertical displacement and a velocity profile. We present the results over East Antarctica using data from the high-capability radar sounder (HiCARS) system. We show two scenarios that demonstrate the feasibility, limitations, and requirements of this approach. [ABSTRACT FROM AUTHOR]

The main purpose of this article is to emphasize the importance of clarifying the probabilistic framework adopted for volcanic hazard and eruption forecasting. Eruption forecasting and volcanic hazard analysis seeks to quantify the deep uncertainties that pervade the modeling of pre-, sin- and post-eruptive processes. These uncertainties can be differentiated into three fundamental types: (1) the natural variability of volcanic systems, usually represented as stochastic processes with parameterized distributions (aleatory variability); (2) the uncertainty in our knowledge of how volcanic systems operate and evolve, often represented as subjective probabilities based on expert opinion (epistemic uncertainty); and (3) the possibility that our forecasts are wrong owing to behaviors of volcanic processes about which we are completely ignorant and, hence, cannot quantify in terms of probabilities (ontological error). Here we put forward a probabilistic framework for hazard analysis recently proposed by Marzocchi & Jordan (2014), which unifies the treatment of all three types of uncertainty. Within this framework, an eruption forecasting or a volcanic hazard model is said to be complete only if it (a) fully characterizes the epistemic uncertainties in the model's representation of aleatory variability and (b) can be unconditionally tested (in principle) against observations to identify ontological errors. Unconditional testability, which is the key to model validation, hinges on an experimental concept that characterizes hazard events in terms of exchangeable data sequences with well-defined frequencies. We illustrate the application of this unified probabilistic framework by describing experimental concepts for the forecasting of tephra fall from Campi Flegrei. Eventually, this example may serve as a guide for the application of the same probabilistic framework to other natural hazards. [ABSTRACT FROM AUTHOR]

Radar‐sounding surveys associated with the discovery of a large impact crater beneath Hiawatha Glacier, Greenland, revealed bright, flat subglacial reflections hypothesized to originate from a subglacial groundwater table. We test this hypothesis using radiometric and hydrologic analysis of those radar data. The dielectric loss between the reflection from the top of the basal layer and subglacial reflection and their reflectivity difference represent dual constraints upon the complex permittivity of the basal material. Either ice‐cemented debris or fractured, well‐drained bedrock explain the basal layer's radiometric properties. The subglacial reflector's geometry is parallel to isopotential hydraulic head contours, located 7.5–15.3 m below the interface, and 11 ± 7 dB brighter than the ice–basal layer reflection. We conclude that this subglacial reflection is a groundwater table and that its detection was enabled by the wide bandwidth of the radar system and unusual geologic setting, suggesting a path for future direct radar detection of subglacial groundwater elsewhere. Plain Language Summary: Recent radar sounding of the Hiawatha Glacier, which overlies a large impact crater, also found an unusually flat, bright surface about 10 meters beneath the bottom of the ice. This surface was suspected to be the groundwater table, which has never been directly detected by radar beneath an ice sheet, but was not studied in detail. We used two three‐layer geologic models to test this hypothesis using the strength of the radar returns. We found that the layer between the ice bottom and this lower surface is likely either debris‐laden ice or fractured, well‐drained bedrock. This surface's shape and brightness are also consistent with a groundwater table and follow expected patterns of water pressure. Our results confirm the detection of a groundwater table beneath Hiawatha Glacier and show the potential for future radar surveys to further probe subglacial groundwater systems. Key Points: Radiometric and hydrologic analysis of radar‐sounding data is consistent with a reflection from a subglacial groundwater tableDual radiometric constraints indicate a layer of either debris‐laden ice or fractured bedrock above the subglacial groundwater tableThis first detection of a subglacial groundwater table was enabled by favorable local geology, thin ice and the wide bandwidth radar system [ABSTRACT FROM AUTHOR]

Working on strongly irreducible planar self-affine sets satisfying the strong open set condition, we calculate the Birkhoff spectrum of continuous potentials and the Lyapunov spectrum. [ABSTRACT FROM AUTHOR]

For self‐similar sets on R satisfying the exponential separation condition we show that the dimension of natural projections of shift invariant ergodic measures is equal to min{1,h−χ}, where h and χ are the entropy and Lyapunov exponent, respectively. The proof relies on Shmerkin's recent result on the Lq dimension of self‐similar measures. We also use the same method to give results on convolutions and orthogonal projections of ergodic measures projected onto self‐similar sets. [ABSTRACT FROM AUTHOR]

Drawing on the historical importance of visual interpretation for image understanding and knowledge discovery, emerging technologies in geovisualization are incorporated into research, education and outreach at the Center for Geospatial Research (CGR) in the Department of Geography at the University of Georgia (UGA), USA. This study aimed to develop the 3D Immersion and Geovisualization (3DIG) system consisting of uncrewed aerial systems (UAS) for data acquisition, augmented and virtual reality headsets and mobile devices, an augmented reality digital sandbox, and a video wall. We were working together integrated data products from the UAS imagery, including digital image mosaics and 3D models, and readily available gaming engine software to create augmented and virtual reality immersive visualizations. The use of 3DIG in research is demonstrated in a case study documenting the seasonal growth of vegetables in small gardens with a time series of 3D crop models generated from UAS imagery and Structure from Motion photogrammetry. Demonstrations of 3DIG in geography and geology courses, as well as public events, also indicate the benefits of emerging geospatial technologies for creating active learning environments and fostering participatory community engagement. [ABSTRACT FROM AUTHOR]

Stream water quality data are essential for understanding watershed processes and managing water pollution, but the effort and expense of stream monitoring limit how many watersheds can be studied. For 59 small watersheds in the Chesapeake Bay drainage, we compared water quality measurements from inexpensive spot sampling to data from costly automated monitoring that used 1–3 yr of continuous flow measurement and weekly, temporally composited water sampling. Mean nitrogen (N) levels ranged from 0.01 to 16 mg N/L among streams. There were important temporal variations in N concentrations at each site, but the differences among sites were much greater. Spot samples were very effective at accurately and precisely placing average stream N levels within the N gradient among streams draining N‐enriched watersheds. Among watersheds, nitrate (NO3) and total N concentrations from spot samples were very strongly correlated with means from weekly composite sampling (R2 > 97%). We confirmed this result for independent data for 85 larger watersheds in the Chesapeake Bay Non‐tidal Network. NO3 concentration from a single March spot sample was highly correlated (R2 > 92%) with flow‐weighted average total N concentration synthesized from five years of monitoring. Spot sampling effectively quantifies average N status across N‐enriched watersheds because most N moves as dissolved NO3 in subsurface flow and that flux is much less variable than the episodic surface transport of particulate materials. For questions answered by quantifying average N levels, spot sampling can assess more watersheds at much lower cost than automated sampling, so it should be more widely used to support cost‐effective N research and management. For materials that are mainly bound to particulates, such as phosphorus, spot sampling is much less effective. [ABSTRACT FROM AUTHOR]

Here we use polarimetric measurements from an Autonomous phase-sensitive Radio-Echo Sounder (ApRES) to investigate ice fabric within Whillans Ice Stream, West Antarctica. The survey traverse is bounded at one end by the suture zone with the Mercer Ice Stream and at the other end by a basal 'sticky spot'. Our data analysis employs a phase-based polarimetric coherence method to estimate horizontal ice fabric properties: the fabric orientation and the magnitude of the horizontal fabric asymmetry. We infer an azimuthal rotation in the prevailing horizontal c-axis between the near-surface (z ≈ 10–50 m) and deeper ice (z ≈ 170–360 m), with the near-surface orientated closer to perpendicular to flow and deeper ice closer to parallel. In the near-surface, the fabric asymmetry increases toward the center of Whillans Ice Stream which is consistent with the surface compression direction. By contrast, the fabric orientation in deeper ice is not aligned with the surface compression direction but is consistent with englacial ice reacting to longitudinal compression associated with basal resistance from the nearby sticky spot. [ABSTRACT FROM AUTHOR]

We study equilibrium measures (Käenmäki measures) supported on self-affine sets generated by a finite collection of diagonal and anti-diagonal matrices acting on the plane and satisfying the strong separation property. Our main result is that such measures are exact dimensional and the dimension satisfies the Ledrappier-Young formula, which gives an explicit expression for the dimension in terms of the entropy and Lyapunov exponents as well as the dimension of a coordinate projection of the measure. In particular, we do this by showing that the Käenmäki measure is equal to the sum of (the pushforwards) of two Gibbs measures on an associated subshift of finite type. [ABSTRACT FROM AUTHOR]

We map crustal regions in Southern California that have similar depth variations in seismic velocities by applying cluster analysis to 1.5 million P and S velocity profiles from the three‐dimensional tomographic model CVM‐S4.26. We use a K‐means algorithm to partition the profiles into K sets that minimize the inter‐cluster variance. The regionalizations for K ≤ 10 generate a coherent sequence of structural refinements: each increment of K introduces a new region typically by partitioning a larger region into two smaller regions or by occupying a transition zone between two regions. The results for K ≤ 7 are insensitive to initialization and trimming of the model periphery; nearly identical results are obtained if the P and S velocity profiles are treated separately or jointly. The regions for K = 7 can be associated with major physiographic provinces and geologic areas with recognized tectonic affinities, including the Continental Borderland, Great Valley, Salton Trough, and Mojave Desert. The regionalization splits the Sierra Nevada and Peninsular Range batholiths into the western and eastern zones consistent with geological, geochemical, and potential‐field mapping. Three of the regions define a geographic domain comprising almost all of the upper crust derived from continental lithosphere. Well‐resolved regional boundaries coincide with major faults, topographic fronts, and/or geochemical transitions mapped at the surface. The consistent alignment of these surface features with deeper transitions in the crustal velocity profiles indicates that regional boundaries are typically narrow, high‐angle structures separating regions with characteristic crustal columns that reflect different compositions and tectonic histories. Key Points: Crustal regions in Southern California with similar seismic velocity profiles are mapped by applying cluster analysis to a tomographic modelRegions correspond to major physiographic provinces and geologic areas with known tectonic affinitiesRegion boundaries are typically narrow, high‐angle structures that separate regions with different crustal compositions and tectonic histories [ABSTRACT FROM AUTHOR]

Ice crystal orientation fabric (COF) records information about past ice-sheet deformation and influences the present-day flow of ice. Polarimetric radar sounding provides a means to infer anisotropic COF patterns due to the associated birefringence of polar ice. Here, we develop a polarimetric coherence (phase-based) method to determine horizontal properties of the COF. The method utilizes the azimuth and depth dependence of the vertical gradient of the hhvv coherence phase to infer the dielectric principal axes and birefringence, which are then related to the second-order fabric orientation tensor. Specifically, under the assumption that one of the orientational eigenvectors is vertical, we can determine the horizontal eigenvectors and the difference between the horizontal eigenvalues (a measure of horizontal fabric asymmetry). The method exploits single-polarized data acquired with varying antenna orientation. It applies to ground-based “multi-polarization” surveys and is demonstrated using data acquired by Center for Remote Sensing of Ice Sheets (CReSIS) using Multi-Channel Coherent Radar Depth Sounder (MCRDS) from the North Greenland Eemian Ice Drilling (NEEM) ice core region in Greenland. The analysis is validated using a combination of polarimetric matrix backscatter simulations and comparison with COF data from the NEEM ice core. The results are consistent with a conventional model of ice deformation at an ice divide where a lateral tension component is present, with minor horizontal COF asymmetry and the greatest horizontal concentration of crystallographic axes orientated near parallel to the ice divide. [ABSTRACT FROM AUTHOR]

The subglacial environment of the Greenland Ice Sheet (GrIS) is poorly constrained both in its bulk properties, for example geology, the presence of sediment, and the presence of water, and interfacial conditions, such as roughness and bed rheology. There is, therefore, limited understanding of how spatially heterogeneous subglacial properties relate to ice-sheet motion. Here, via analysis of 2 decades of radio-echo sounding data, we present a new systematic analysis of subglacial roughness beneath the GrIS. We use two independent methods to quantify subglacial roughness: first, the variability in along-track topography – enabling an assessment of roughness anisotropy from pairs of orthogonal transects aligned perpendicular and parallel to ice flow and, second, from bed-echo scattering – enabling assessment of fine-scale bed characteristics. We establish the spatial distribution of subglacial roughness and quantify its relationship with ice flow speed and direction. Overall, the beds of fast-flowing regions are observed to be rougher than the slow-flowing interior. Topographic roughness exhibits an exponential scaling relationship with ice surface velocity parallel, but not perpendicular, to flow direction in fast-flowing regions, and the degree of anisotropy is correlated with ice surface speed. In many slow-flowing regions both roughness methods indicate spatially coherent regions of smooth beds, which, through combination with analyses of underlying geology, we conclude is likely due to the presence of a hard flat bed. Consequently, the study provides scope for a spatially variable hard- or soft-bed boundary constraint for ice-sheet models. [ABSTRACT FROM AUTHOR]

To control invasive species and prioritize limited resources, managers need information about population size to evaluate the current state of the problem, the trend in population growth through time, and to understand the potential magnitude of the problem in the absence of management actions. This information is critical for informing management actions and allocating resources. We used two national-scale data sets to estimate historical, current, and future potential population size of invasive wild pigs (Sus scrofa; hereafter wild pigs) in the United States. Between 1982 to present, the Southeastern Cooperative Wildlife Disease Study mapped the distribution of wild pigs in the United States. In addition, recent research has predicted potential population density of wild pigs across the United States by evaluating broad-scale landscape characteristics. We intersected these two data sets to estimate the population size of wild pigs in 1982, 1988, 2004, 2010, 2013, and 2016. In addition, we estimated potential population size if wild pigs were present at equilibrium conditions in all available habitat in each state. We demonstrate which states have experienced recent population growth of wild pigs and are predicted to experience the greatest population increase in the future without sufficient management actions and policy implementation. Regions in the western, northern, and northeastern United States contain no or few wild pig populations, but could potentially support large numbers of these animals if their populations become established. This information is useful in identifying regions at greatest risk if wild pigs become established, which can assist in prioritizing management actions aimed at controlling or eliminating this invasive species across broad to local scales. [ABSTRACT FROM AUTHOR]

Saltwater intrusion is the leading edge of sea-level rise, preceding tidal inundation, but leaving its salty signature far inland. With climate change, saltwater is shifting landward into regions that previously have not experienced or adapted to salinity, leading to novel transitions in biogeochemistry, ecology, and human land uses. We explore these changes and their implications for climate adaptation in coastal ecosystems. Biogeochemical changes, including increases in ionic strength, sulfidation, and alkalinization, have cascading ecological consequences such as upland forest retreat, conversion of freshwater wetlands, nutrient mobilization, and declines in agricultural productivity. We explore the trade-offs among land management decisions in response to these changes and how public policy should shape socioecological transitions in the coastal zone. Understanding transitions resulting from saltwater intrusion—and how to manage them—is vital for promoting coastal resilience. [ABSTRACT FROM AUTHOR]

Seismic radiation from indigenous sources can be represented by the excess of model stress over actual stress, a second-order tensor field that Backus & Mulcahy named the stress glut. We prove a new representation theorem that exactly and uniquely decomposes any stress-glut (or strain-glut) density into a set of orthogonal tensor fields of increasing degree α, up to six in number, ordered by their first non-zero polynomial moments. The zeroth-degree field (⁠|$\alpha = 0$|⁠) is the projection of the stress-glut density onto its zeroth polynomial moment, which defines the seismic moment tensor, Aki seismic moment |${M_0}$|⁠, and centroid-moment tensor (CMT) point source. The higher-degree fields describe mechanism complexity—source variability that arises from the space-time variations in the orientation of the stress glut, which is the main subject of this theoretical study. The representation theorem generalizes the point-source approximation to a sum of multipoles that features the CMT monopole as its leading term. The first-degree field contributes a dipole tensor with an mechanism orthogonal to the CMT, the second-degree field contributes a quadrupole tensor, and so on, up to six orthogonal fields in all. We define the total scalar moment |${M_{\rm{T}}}$| to be the integral of the scalar moment density, and we use the representation theorem to partition this total moment into a sum of fractional moments for each degree α. If the faulting is simple enough, |${M_{\rm{T}}} \approx {M_0}$|⁠, and the higher-degree terms will be small. When the faulting is more complex, however, |${M_{\rm{T}}} > {M_0}$|⁠ ; the higher-degree fields will contribute more to the radiation, and this contribution will increase with frequency. Application to simple planar faulting shows that out-of-plane variations in slip-vector orientation reduce |${M_0}/{M_{\rm{T}}}$| more than in-plane variations of similar magnitude, consistent with Kagan's early study of mechanism complexity. We decompose stress-glut realizations from the Graves & Pitarka rupture simulator; typical values of |${M_0}/{M_{\rm{T}}}$| are 0.82–0.92, consistent with analytical results. The higher-degree fields of the Graves–Pitarka sources typically radiate up to |$\alpha = 4$|⁠ ; only the isotropic term is zero. We compute synthetic seismograms to illustrate the radiation patterns of the higher-degree fields and their frequency dependence. Decomposition of the Duputel & Rivera source model for the 2016 Kaikōura earthquake (M w 7.8) indicates that the radiation from the higher-degree fields was large enough (⁠|${M_0}/{M_{\rm{T}}}\ = 0.82$|⁠) that it may be possible to invert global datasets for low-degree multipoles. Other applications of the stress-glut representation theorem are discussed. [ABSTRACT FROM AUTHOR]

As global sea-levels rise, low-lying coastal lands are subject to shallow coastal flooding and saltwater intrusion, affecting the productivity of farmlands worldwide. Soil biogeochemistry can be dramatically altered as saltwater intrudes agricultural fields. We selected three farm fields in Somerset Co., Maryland affected by saltwater intrusion and established transects from the ditch bank to the center of the cropped field and collected soils (to ~ 140 cm) at five points along this transect. The three fields in this study have different soil types, are located along different tributaries in the county, and receive different fertilizer rates, yet they all showed similar biogeochemical responses to saltwater intrusion. We found an increase in electrical conductivity and concentrations of chloride, sulfate, and forms of phosphorus (P) from the center of the field (low) to the ditch banks (high). As inundation increased, the structure of iron (Fe) changed from crystalline to non-crystalline forms, possibly due to dissolution under saturated conditions. Near the edges of the fields, the formation of organometallic complexes was positively associated with increases in soil carbon and organic soil P concentrations. Compared to areas of the fields where crops were actively growing, soil P concentrations are 2-3 higher on field edges, suggesting that saltwater intrusion may be transporting P to the edges of agricultural fields. These field edges are frequently saturated, thus reduction of Fe could lead to P release into solution potentially harming water quality. As climate change pushes saltwater further inland, it is important to understand the biogeochemical consequences for ecosystems up- and downstream. Understanding the how fractions of P move and change across fields affected by saltwater intrusion will be crucial for planning current and future management of coastal agricultural lands. [ABSTRACT FROM AUTHOR]

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The attenuation of solar radiation controls many processes and characteristics of aquatic ecosystems and is a sentinel of larger‐scale environmental change. While light attenuation is often characterized with a single broadband diffuse attenuation coefficient of photosynthetically active radiation (Kd PAR), attenuation can exhibit substantial variability across the solar spectrum and through time and space. Understanding this variability and its proximate causes may provide information to characterize large‐scale environmental change. We implemented a semi‐analytical Kd model in four segments of the Rhode River sub‐estuary of the Chesapeake Bay to examine spectral, spatial, and temporal variability in Kd across the ultraviolet (UV) to PAR wavelengths (290–710 nm) over the period 1986–2014. We used this model to identify wavelengths most sensitive to long‐term change, the seasonal phenology of long‐term change, and the optical constituents driving changes. The model included contributions by phytoplankton, non‐algal particulates, chromophoric dissolved organic matter (CDOM), and water. Over the period of record, Kd increased (water transparency decreased) in both UV and PAR wavelengths, with the largest increases at the most upstream site, during summer months, and at short UV wavelengths. These increases were due primarily to an increase in non‐algal particulates, and particularly since year 2005, however there was substantial seasonality in Kd. The model reveals how different changes in water quality have a differential effect on UV and PAR attenuation, and enables insight into what types of long‐term change in transparency have occurred over the long period of human impacts in the Chesapeake Bay watershed. [ABSTRACT FROM AUTHOR]

To account for the randomness (aleatory variability) and limited knowledge (epistemic uncertainty) of earthquake processes, we must formulate and test seismic hazard models using the concepts of probability. Probabilistic seismic hazard analysis (PSHA) gives the chance that a specified seismic intensity will be exceeded at a particular site during some future time window. Because knowledge of that chance is uncertain, a complete PSHA estimate of probabilities must itself be expressed as a probability distribution, often quantified using expert opinion. The conceptual objections to PSHA stem primarily from the unsatisfactory treatment of the aleatory-epistemic duality in probabilistic inference and questions regarding the inherent testability of subjective models. We have proposed an augmented probabilistic framework that resolves these issues by adding a third level of uncertainty, which we term 'ontological error' (PNAS, 111, 11973, 2014). A complete probabilistic model is sufficient to pose an ontological null hypothesis, which states that the aleatory representation of future earthquake activity—the seismic behaviour of the real Earth—samples the probability distribution of aleatory representations that describe the model's epistemic uncertainty. We can test, and possibly reject, the ontological null hypothesis by employing an 'experimental concept' that identifies collections of data, observed and not yet observed, judged to be exchangeable (i.e. with joint probability distributions invariant to data ordering) when conditioned on a set of explanatory variables. These conditional exchangeability judgments specify data sequences with well-defined frequencies. Bayesian models that predict such long-run frequencies can thus be tested for ontological error by frequentist methods, for example using P -values. We describe examples of experimental concepts pertinent to the ontological testing of complete probabilistic earthquake forecasting models. The examples, which include both simple and compound exceedance testing, illustrate how test distributions can be derived from the de Finetti representation and its generalizations, the use of hierarchical statistical models to express the various layers of aleatory variability, and the importance of the 'Principle of Complete Ignorance' in characterizing ontological errors. We also show how differing experimental concepts can probe different model features and explore how experimental concepts can themselves be tested. [ABSTRACT FROM AUTHOR]

The nearshore land-water interface is an important ecological zone that faces anthropogenic pressure from development in coastal regions throughout the world. Coastal waters and estuaries like Chesapeake Bay receive and process land discharges loaded with anthropogenic nutrients and other pollutants that cause eutrophication, hypoxia, and other damage to shallow-water ecosystems. In addition, shorelines are increasingly armored with bulkhead (seawall), riprap, and other structures to protect human infrastructure against the threats of sea-level rise, storm surge, and erosion. Armoring can further influence estuarine and nearshore marine ecosystem functions by degrading water quality, spreading invasive species, and destroying ecologically valuable habitat. These detrimental effects on ecosystem function have ramifications for ecologically and economically important flora and fauna. This special issue of Estuaries and Coasts explores the interacting effects of coastal land use and shoreline armoring on estuarine and coastal marine ecosystems. The majority of papers focus on the Chesapeake Bay region, USA, where 50 major tributaries and an extensive watershed (~ 167,000 km2), provide an ideal model to examine the impacts of human activities at scales ranging from the local shoreline to the entire watershed. The papers consider the influence of watershed land use and natural versus armored shorelines on ecosystem properties and processes as well as on key natural resources. [ABSTRACT FROM AUTHOR]

Nutrient inputs have degraded estuaries worldwide. We investigated the sources and effects of nutrient inputs by comparing water quality at shallow (< 2m deep) nearshore (within 200 m) locations in a total of 49 Chesapeake subestuaries and Mid-Atlantic coastal bays with differing local watershed land use. During July-October, concentrations of total nitrogen (TN), dissolved ammonium, dissolved inorganic N (DIN), and chlorophyll a were positively correlated with the percentages of cropland and developed land in the local watersheds. TN, DIN, and nitrate were positively correlated with the ratio of watershed area to subestuary area. Total phosphorus (TP) and dissolved phosphate increased with cropland but were not affected by developed land. The relationships among N, P, chlorophyll a, and land use suggest N limitation of chlorophyll a production from July-October. We compared our measurements inside the subestuaries to measurements by the Chesapeake Bay Program in adjacent estuarine waters outside the subestuaries. TP and dissolved inorganic P concentrations inside the subestuaries correlated with concentrations outside the subestuaries. However, water quality inside the subestuaries generally differed from that in adjacent estuarine waters. The concentration of nitrate was lower inside the subestuaries, while the concentrations of other forms of N, TP, and chlorophyll a were higher. This suggests that shallow nearshore waters inside the subestuaries import nitrate while exporting other forms of N as well as TP and chlorophyll a. The importance of local land use and the distinct biogeochemistry of shallow waters should be considered in managing coastal systems. [ABSTRACT FROM AUTHOR]

We provide an example of how one estuarine research project engaged regional managers to help guide the research towards the needs of managers and policymakers dealing with shoreline management in the Mid-Atlantic region of the USA. Elements of the approach that contributed to success included a well-targeted initial request for proposals, a review process that included management input both as a review criterion and on the review panel, a careful process in choosing advisory members at the appropriate level in the agencies, regular opportunities for interactions between the management advisory group and the science team, and active involvement of a program manager as liaison throughout the life of the project. Engagement of a management advisory group changed some of the scientific approaches, helped to communicate results, and formed a foundation for incorporation into regional management and initiatives. [ABSTRACT FROM AUTHOR]

There is widespread, but often indirect, evidence that a significant fraction of the bed beneath the Greenland Ice Sheet is thawed (at or above the pressure melting point for ice). This includes the beds of major outlet glaciers and their tributaries and a large area around the NorthGRIP borehole in the ice-sheet interior. The ice-sheet-scale distribution of basal water is, however, poorly constrained by existing observations. In principle, airborne radio-echo sounding (RES) enables the detection of basal water from bed-echo reflectivity, but unambiguous mapping is limited by uncertainty in signal attenuation within the ice. Here we introduce a new, RES diagnostic for basal water that is associated with wet-dry transitions in bed material: bed-echo reflectivity variability. This technique acts as a form of edge detector and is a sufficient, but not necessary, criteria for basal water. However, the technique has the advantage of being attenuation insensitive and suited to combined analysis of over a decade of Operation IceBridge survey data. The basal water predictions are compared with existing analyses of the basal thermal state (frozen and thawed beds) and geothermal heat flux. In addition to the outlet glaciers, we demonstrate widespread water storage in the northern and eastern interior. Notably, we observe a quasilinear "corridor" of basal water extending from NorthGRIP to Petermann Glacier that spatially correlates with elevated heat flux predicted by a recent magnetic model. Finally, with a general aim to stimulate regional- and process-specific investigations, the basal water predictions are compared with bed topography, subglacial flow paths and ice-sheet motion. The basal water distribution, and its relationship with the thermal state, provides a new constraint for numerical models. [ABSTRACT FROM AUTHOR]

Abstract: Curie depths beneath Greenland are revealed by spectral analysis of data from the World Digital Magnetic Anomaly Map 2. A thermal model of the lithosphere then provides a corresponding geothermal heat flux map. This new map exhibits significantly higher frequency but lower amplitude variation than earlier heat flux maps and provides an important boundary condition for numerical ice‐sheet models and interpretation of borehole temperature profiles. In addition, it reveals new geologically significant features. Notably, we identify a prominent quasi‐linear elevated geothermal heat flux anomaly running northwest–southeast across Greenland. We interpret this feature to be the relic of the passage of the Iceland hotspot from 80 to 50 Ma. The expected partial melting of the lithosphere and magmatic underplating or intrusion into the lower crust is compatible with models of observed satellite gravity data and recent seismic observations. Our geological interpretation has potentially significant implications for the geodynamic evolution of Greenland. [ABSTRACT FROM AUTHOR]

Abstract: Accurate models of crustal attenuation structure are important for simulating seismic wavefields at high frequencies (f > 1 Hz). In this study, we collected P and S waveforms from 160 regional earthquakes (3.3 ≤ M ≤ 5.7) recorded at 218 broadband stations of Southern California Seismic Network and measured spectral amplitudes of P and S waves in the 1‐ to 10‐Hz band using integrals over wavelet transforms. We accounted for source structure and geometrical spreading by referencing the spectral amplitudes to values computed from 1‐D synthetic seismograms. We inverted the spectral amplitude ratios for a 1‐D, frequency‐dependent crustal attenuation model. When plotted against wavenumber, the depth averages of both QP and QS are described by the same function, Q(k) = (240 ± 20) k0.40 ± 0.05 (1 km−1 ≤ k ≤ 17 km−1). Our results are consistent with attenuation dominated by first‐order Born scattering from an isotropic, self‐affine distribution of elastic heterogeneities with an outer scale of ~10 km, a root‐mean‐square relative amplitude of ~8% and a fractal dimension of ~3.8. The inversions accounted for frequency‐dependent variations in the source spectra and site response. The source spectra roll off at an average rate of about 2 for both wave types. The station residuals, which reflect unresolved lateral structure, show stronger attenuation in the Los Angeles region and weaker attenuation in the batholithic terrains to the north and south, as well as in the Proterozoic terrains on the eastern side of the study region. [ABSTRACT FROM AUTHOR]

Abstract: Body‐wave and normal‐mode observations of Earth's inner core show cylindrical anisotropy consistent with an alignment of hexagonal close‐packed iron (hcp‐Fe) crystals along the rotation axis. We quantify the degree of alignment by comparing seismic observations longitudinally averaged over the outer 600 km of the inner core with stochastic rotation models based on ab initio calculations of hcp‐Fe stiffness tensors. Likelihood functions are constructed for the Woodhouse anisotropy ratios from an ensemble of normal‐mode models and for the Backus ray‐angle parameters from the Irving‐Deuss traveltime data set. The tensor at each inner‐core location is modeled as a random rotation of the hcp‐Fe stiffness tensor, and the rotations are assumed to have transversely isotropic statistics with correlation lengths that are small compared to the seismic wavelengths. Two stochastic rotation models are used, one based on Fisher statistics (F model) with concentration parameter κ and one by Jordan (J model) with orientation ratio ξ. The first‐order estimates, obtained by Voigt averaging, imply that hcp‐Fe tensors by Martorell and others considering premelting softening can account for the seismic data if the hcp‐Fe axes are moderately aligned with Earth's rotation axis ( κ = 2.1 − 0.6 + 1.9, ξ = 0.6 0 − 0.15 + 0.13). The J model is extended to include second‐order Born scattering, which in the low‐frequency limit depends on the aspect ratio η of the transversely isotropic correlation tensor. Although η is not usefully constrained by the existing data, we show that second‐order scattering acts to increase the required bipolar concentration of hcp‐Fe axes. Integrating over η yields the marginal estimate ξ = 0 . 52 − 0.12 + 0.19, corresponding to a 50% dispersion angle of 42 ° − 7 ° + 9 °. [ABSTRACT FROM AUTHOR]