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Intracortical microelectrode arrays (MEAs) are currently limited in their chronic functionality due partially to the foreign body response (FBR) that develops in regions immediately surrounding the implant (typically within 50–100 µm). Mechanically flexible, polymer-based substrates have recently been explored for MEAs as a way of minimizing the FBR caused by the chronic implantation. Nonetheless, the FBR degrades the ability of the device to record neural activity. We are motivated to develop approaches to deploy multiple recording sites away from the initial site of implantation into regions of tissue outside the FBR zone. Liquid Crystal Elastomers (LCEs) are responsive materials capable of programmable and reversible shape change. These hydrophobic materials are also non-cytotoxic and compatible with photolithography. As such, these responsive materials may be well suited to serve as substrates for smart, implantable electronics. This study explores the feasibility of LCE-based deployable intracortical MEAs. LCE intracortical probes are fabricated on a planar substrate and adopt a 3D shape after being released from the substrate. The LCE probes are then fixed in a planar configuration using polyethylene glycol (PEG). The PEG layer dissolves in physiological conditions, allowing the LCE probe to deploy post-implantation. Critically, we show that LCE intracortical probes will deploy within a brain-like agarose tissue phantom. We also show that deployment distance increases with MEA width. A finite element model was then developed to predict the deformed shape of the deployed probe when embedded in an elastic medium. Finally, LCE-based deployable intracortical MEAs were capable of maintaining electrochemical stability, recording extracellular signals from cortical neurons in vivo , and deploying recording sites greater than 100 µm from the insertion site in vivo. Taken together, these results suggest the feasibility of using LCEs to develop deployable intracortical MEAs. Deployable MEAs are a recently developed class of neural interfaces that aim to shift the recording sites away from the region of insertion to minimize the negative effects of FBR on the recording performance of MEAs. In this study, we explore LCEs as a potential substrate for deployable MEAs. The novelty of this study lies in the systematic and programmable deployment offered by LCE-based intracortical MEAs. These results illustrate the feasibility and potential application of LCEs as a substrate for deployable intracortical MEAs. Image, graphical abstract [ABSTRACT FROM AUTHOR]

We have characterized the in vitro and in vivo extracellular neural recording and stimulation properties of ruthenium oxide (RuOx) based microelectrodes. Cytotoxicity and functional neurotoxicity assays were carried out to confirm the in vitro biocompatibility of RuOx. Material extract assays, in accordance to ISO protocol "10993-5: Biological evaluation of medical devices", revealed no significant effect on neuronal cell viability or the functional activity of cortical networks. In vitro microelectrode arrays (MEAs), with indium tin oxide (ITO) sites modified with sputtered iridium oxide (IrOx) and RuOx in a single array, were developed for a direct comparison of electrochemical and recording performance of RuOx to ITO and IrOx deposited microelectrode sites. The impedance of the RuOx-coated electrodes measured by electrochemical impedance spectroscopy was notably lower than that of ITO electrodes, resulting in robust extracellular recordings from cortical networks in vitro. We found comparable signal-to-noise ratios (SNRs) for RuOx and IrOx, both significantly higher than the SNR for ITO. RuOx-based MEAs were also fabricated and implanted in the rat motor cortex to demonstrate manufacturability of the RuOx processing and acute recording capabilities in vivo. We observed single-unit extracellular action potentials with a SNR >22, representing a first step for neurophysiological recordings in vivo with RuOx based microelectrodes. A critical challenge in neural interface technology is the development of microelectrodes that have recording and electrical stimulation capabilities suitable for bidirectional communication between the external electronic device and the nervous system. The present study explores the feasibility and functional capabilities of ruthenium oxide microelectrodes as a neural interface. Significant improvement in electrochemical properties and neuronal recordings are reported when compared to commercially available indium tin oxide and was similar to that of iridium oxide electrodes. The data demonstrate the potential for future development of chronic neural interfaces using ruthenium oxide based microelectrodes for recording and stimulation. Image, graphical abstract [ABSTRACT FROM AUTHOR]

The northeastern Chukchi Sea is a shallow subarctic shelf ecosystem that supports a substantial benthic infaunal community of which bivalves are a major component. We assessed the patterns in population abundance, biomass, and caloric content of ten dominant bivalve taxa in relation to the distribution of the upper trophic level consumer Pacific walrus ( Odobenus rosmarus divergens ). Bivalves were collected over four cruises in the northeastern Chukchi Sea (2009, 2010, 2012, 2013). Our samples were largely dominated by calorie-dense, deposit-feeding species, including Macoma spp., Ennucula tenuis , Nuculana spp. and Yoldia spp. Weight-frequency distributions were strongly right-skewed for most taxa, though some showed evidence of a bimodal distribution. Caloric densities as measured through bomb calorimetry significantly differed among taxa (ANOVA F = 32.57, df = 9, p-value<0.001), and whole animal wet weight was found to be a reliable predictor of whole animal caloric content. Bivalve populations and peak caloric densities were centered on and to the southeast of Hanna Shoal, which coincided with peak Pacific walrus relative density (walruses per km surveyed) from July through October. Significant differences in mean caloric values were found between areas with and without walruses present (student's t-test, t=−2.9088, df = 252.24, p-value = 0.003952), as well as between areas with low and high walrus relative densities in the pooled annual dataset and in each individual month except October (ANOVA, p-value<0.05). The high-calorie deposit feeders that dominate these bivalve communities preferentially consume food sources, such as sea ice algae, that are likely to be affected by shifting sea ice dynamics. As such, continued warming has the potential to alter bivalve communities in the northeastern Chukchi Sea, which may have profound implications for upper trophic levels. [ABSTRACT FROM AUTHOR]

We evaluated the potential of Glycymeris pilosa as an environmental indicator for the Mediterranean region by applying sclerochronological techniques on a sample set collected from Pašman Channel in the middle Adriatic Sea. Maximal longevity of analyzed shells was 69 years. Growth increments in acetate peels of the hinge region had clear boundaries, and there was a strongly synchronous signal in growth-increment width among individuals. The final, replicated chronology spanned 1969 to 2013. Shell growth negatively correlated with local summer sea temperatures and positively with November precipitation. High correlation between shell growth and circulation patterns in the northern Ionian was also observed, with slower growth occurring during cyclonic regimes. Given its broad distribution in the region and the ability to crossdate, generate annually-resolved chronologies, and of a length that substantially overlaps with observational records, G. pilosa has considerable potential to test hypotheses relating to environmental variability and biological response in the Mediterranean. [ABSTRACT FROM AUTHOR]

Abstract: Tree-ring analysis was applied to assess the impacts of the fungal disease Swiss needle cast on the radial growth of mature Douglas-fir (Pseudotsuga menziesii) forests in the western Oregon Coast Range. Although considered endemic to the Pacific Northwest, Swiss needle cast has significantly lowered productivity in Douglas-fir forests only in the past 20–30 years. To date, studies on Swiss needle cast impacts have almost exclusively involved young (<30 years) plantation trees. To better describe the history of Swiss needle cast and its impacts on older (>80 years) trees, we extracted tree cores from dominant and codominant Douglas-fir and western hemlock (Tsuga heterophylla) in three even-aged stands in western Oregon. In the least affected stand growth rates of both species did not significantly differ, while at the most severely diseased site Douglas-fir radial growth was reduced by as much as 85%. Growth reductions likely associated with Swiss needle cast were dated to as early as 1950, though the most severe impacts occurred after 1984. An index of Swiss needle cast severity significantly (p <0.01) related to instrumental records of air temperatures such that warm conditions from March through August were associated with reduced radial growth at the most severely affected site. Overall, this study demonstrates that even mature forests of natural origin are susceptible to severe growth reductions by Swiss needle cast, that warmer spring and summer temperatures are associated with Swiss needle cast impacts, and that the disease appears to be increasing in severity. [Copyright &y& Elsevier]

Abstract: The objective of this project was to identify the timing of growth release events detected from tree ring widths and compare whether two cores taken from the same tree reconstructed the same disturbance history. This research question is important because current dendroecological reconstructions of canopy disturbance rely on sampling one core per tree; however, the variation of releases from different cores from the same tree has never been evaluated. We sampled two increment cores from 20 jack pine, 17 white oak, and 19 American beech and identified release events with two commonly employed methods: radial growth averaging technique and boundary line criteria. In jack pine, 85% of the paired cores showed identical releases with the radial growth averaging technique, but 15% of the paired cores varied in reconstructed growth releases. In the jack pine, no releases were identified with the boundary line criteria for any of the paired cores. In the white oak, 65% had identical releases identified with the radial growth averaging technique and 35% of the pairs showed differences. The boundary line criteria for white oak had agreement between releases for 76% of the pairs and different release histories for 24% of the pairs. In the American beech, we were only able to use the radial growth averaging technique and this method showed identical release timing for 79% of the paired cores and differences in 21% of the paired cores. This level of within-tree growth variation is unlikely to influence identification of stand-wide disturbances; however, for reconstructions of small-scale disturbances it is likely to under-represent disturbance events. Therefore, for small-scale disturbance reconstructions, we recommend dendroecologists consider sampling two cores per tree instead of the standard sample of one core per tree. [Copyright &y& Elsevier]

Abstract: Identifying releases from suppression represents one of the most fundamental dendroecological procedures for quantifying forest disturbance histories. In this study we evaluate boundary-line release criteria, which incorporates the effects of growth history on release response. In eastern hemlock (Tsuga canadensis L.) the maximum possible value of a pulse in percent-growth change is dependent on growth decline immediately prior to the pulse. Maximum values of percent-growth-change decline exponentially as prior growth rate increases. This negative exponential rate is quantified as a boundary line, which is used to scale each percent-growth change pulse by the maximum possible value predicted by prior growth rate. The consistency of the relationship between radial growth prior to a release and the magnitude of the release is evaluated in multiple eastern hemlock data sets. Trees from diverse sites show large releases that approach the maximum value predicted by the prior-growth rates. These sites tend to have a history of disturbance, suggesting that disturbance is the most influential variable determining the magnitude of release response. Possible exceptions are sites on the northern and western borders of eastern hemlock''s range, which consistently fall short of the boundary line and may be exhibiting unique relationships between prior growth and percent-growth change. Yet overall the relationship between prior growth and percent-growth change appears to be consistent across much of eastern hemlock''s range. Furthermore, we demonstrate that similar boundary lines occur in Pinus ponderosa (Laws.), Pinus echinata (Mill.), Quercus alba (L.), and Quercus macrocarpa (Michx.). This suggests that prior growth could form the basis of a more unified set of release criteria better able to standardize release responses within and among species. Standardized release criteria would allow more accurate comparisons of disturbance histories among sites, species, and even across landscapes. [Copyright &y& Elsevier]

Crossdating is the defining technique of dendrochronology, ensuring that all measurements in a dataset are annually resolved and absolutely dated. This level of accuracy allows for the development of high-resolution environmental reconstructions of climate, disturbance, and productivity not only in trees, but also in other ring-forming organisms including fish, corals, and bivalves. However, crossdating is a laborious process and can be a significant bottleneck in the development of new chronologies, especially when attempting to find matches among undated, dead-collected material. Several software packages have been developed to aid in crossdating, yet efficiently identifying matches among large numbers of dead-collected samples of unknown antiquity remains a gap in functionality. To address this issue we present RingdateR, a new stand-alone and web-based application for statistical and graphical crossdating that shares many key features with established crossdating applications, but has been optimised for crossdating large collections of dead-collected material. The workflow allows users to load undated measurement time series in common file types (e.g. pos, lps, csv, and xlsx) to be matched against one another (i.e. pairwise analyses) or against an existing chronology. RingdateR provides graphical tools to help identify false or missed rings remaining in the matched measurement time series and to evaluate the impact of the newly crossdated measurement time series on chronology statistics. Whilst the decision as to whether a sample is correctly crossdated ultimately lies with careful visual inspection and discretion of the investigator, guidance from RingdateR can greatly expedite the process, especially when building chronologies that involve dead-collected samples. [ABSTRACT FROM AUTHOR]

Abstract: Growth increment widths from hard structures of marine and freshwater fish and bivalve species are increasingly used to model growth and elucidate relationships with environmental variability. Fully characterizing the intrinsic age-related growth variation among individuals within and between populations, while estimating the extrinsic environmental effects simultaneously, can be challenging. Using the long-lived bivalve Pacific geoduck (Panopea generosa), we develop an integrated approach to analyze the relationship between growth increment data and climate indices using Bayesian hierarchical methods. Fitting models to growth increment data from multiple individuals over two sites, we examined different covariance structures related to random individual effects, long- and short-term environmental effects and unexplained errors. The best fitting hierarchical model accounted for a site-specific mean growth response, individual growth variability through random parameter effects, and site-specific error variances. Extrinsic environmental effects on growth were also significant and included a random year effect and the Pacific Decadal Oscillation (PDO) as a predictor of mean growth across both individuals and sites. Once intrinsic age-related growth was accounted for, PDO accounted for 18% to total variability in growth increment data; geoduck shell size was predicted to increase as a function of larger PDO anomalies. However, the greatest variability in growth increment data was explained by random year effects (∼60–70%), and while largely unexplained, sea surface temperature (SST) is a likely determinant on geoduck growth rates showing a positive growth–SST response. [Copyright &y& Elsevier]

Abstract: The bivalve Pacific geoduck (Panopea generosa) has been used in the eastern North Pacific Ocean to create proxies for environmental factors such as temperature and oceanographic conditions. This type of research depends upon accurate age determination of Pacific geoducks, which historically was based on shell growth-increment counts. A recent study comparing age estimates generated by the dendrochronology (tree-ring science) procedure of crossdating to those estimated from growth-increment counts found a significant difference between the methods for geoduck older than 30years. Compared to the traditional age determination method of counting growth increments, the crossdating method estimates a greater longevity in this species, with some individuals living in excess of 150years. In the present study, the accuracy of each method was independently assessed using bomb-produced radiocarbon (14C) techniques. Specimens whose birth years were estimated to be within the era of the bomb-produced marine 14C increase and where the differences between ages estimated by the two methods were greatest were selected for 14C analysis. The difference between age estimates from traditional growth-increment counts and those from crossdating was evaluated using their respective 14C chronologies in comparisons to a reference chronology as a standard. The comparisons relied on Bayesian nonlinear models using Markov Chain Monte Carlo simulation. This method of analysis showed that with a 50% probability geoducks were aged correctly when using the crossdating method, compared to the growth increment counts which had a 50% probability of underestimating the age by 4years. Therefore, the crossdated age estimates were found to be more accurate than increment counts. Furthermore, these results provide new confidence in using Pacific geoduck biochronologies for paleoclimate and paleoenvironmental reconstruction. [Copyright &y& Elsevier]

• A robust version of Z'-factor was developed for assay quality interpretation for primary DRG neuron-based assay for screening analgesics. • Log-transformed well-wide electrophysiological recordings satisfied normality assumptions. • Robust Z'-factor revealed a value of > 0.5 ("excellent assay"), compared to standard Z'-factor used in HTS assays. • Putative hits were accurately detected in the assay under spontaneous and thermally evoked formats. Cell-based assays comprising primary sensory neurons cultured in vitro are an emerging tool for the screening and identification of potential analgesic compounds and chronic pain treatments. High-content screening (HCS) platforms for drug screening are characterized by a measure of assay quality indicator, such as the Z'-factor, which considers the signal dynamic range and data variation using control compounds only. Although widely accepted as a quality metric in high throughput screening (HTS), standard Z'-factor are not well-suited to indicate the quality of complex cell-based assays. The present study describes a method to assess assay quality in the context of extracellular recordings from dorsal root ganglion (DRG) sensory neurons cultured on multi-well microelectrode arrays. Data transformations are applied to electrophysiological parameters, such as electrode and well spike rates, for valid normality assumptions and suitability for use as a sample signal. Importantly, using transformed well-wide metrics, a robust version of the Z'-factor was applied, based on the median and median absolute deviation, to indicate assay quality and assess hit identification of putative pharmacological compounds. Application of appropriately scaled data and robust statistics ensured insensitivity to data variation and approximation of normal distribution. The use median and median absolute deviation of log transformed well spike rates in computing the Z'-factor revealed a value of 0.61, which is accepted as an "excellent assay." Known antagonists of nociceptor-specific voltage-gated sodium ion channels were identified as true hits in the present assay format under both spontaneous and thermally stimulated conditions. The present approach demonstrated a large signal dynamic range and reduced sensitivity to data variation compared to standard Z'-factor used widely in HTS. Overall, the present study provides a statistical basis for the implementation of a HCS platform utilizing adult DRG neurons on microelectrode arrays. [ABSTRACT FROM AUTHOR]

Reconstructing past environmental variability at short (annual-decadal) time scales is critical for understanding ecosystem change and ecological drivers of evolution. One promising approach to reconstructing that variability is through the use of stable isotope geochemistry and sclerochronology, the study of growth banding in organisms that undergo accretionary growth. We used a combination of sclerochronology, conventional stable isotope ratios and clumped isotope paleotemperatures to improve our understanding of past seasonality and climate variability in the Turkana Basin (Kenya, Ethiopia), which experiences a highly seasonal (tropical semi-desert) climate. In this case study, we apply these approaches to both Early Pleistocene and Holocene bivalve shells (Etheria and Pseudobovaria) to develop a model using various proxies of seasonal-interannual temporal variability in lake temperature and isotope chemistry. We leverage this model to better understand how lakes in the Turkana Basin have changed over short time-scales in the past. One modern (1979) river oyster has exclusively negative δ18O values through ∼1.5 yrs of growth and clumped isotope temperature reconstructions (30.1–31.5 °C) consistent with a river delta provenance. Late Holocene shells show a wider range of isotopic variability within each shell's growth history than the modern sample (∼2‰ for the modern sample vs. 5–7‰ for the Late Holocene samples) and near modern paleotemperatures, suggesting growth under both seasonal Omo flood pulse and lacustrine conditions. Middle Holocene shells exhibit less δ18O variability, consistent with growth in fresher Lake Turkana water at the end of the African Humid Period (12-5 ka), and with both surface water temperatures and water column temperature range similar to the Late Holocene. The Early Pleistocene shells have large seasonal δ18O cycles (4–7‰), with δ18O values comparable to modern and Holocene deltaic shells, and a large range of paleotemperatures (21.8–31.3 °C, including temperatures notably cooler than those measured in the modern lake: 25–31 °C), reflecting growth under significant seasonality in paleo-Omo River runoff. Oxygen isotope cycles suggest high degrees of seasonality of the paleo-Omo River runoff (or that of other major influents) into paleolake Lorenyang at ∼1.6 Ma, which may be similar to modern hydroclimate conditions. Comparison to prior datasets from nearby outcrops in the same basin suggests an increase in hydroclimate seasonality between 1.9 and 1.6 Ma. The combination of clumped isotope paleotemperature estimates from shallow water species such as E. elliptica with TEX 86 measurements (derived here from previously published, contemporaneous sediment core studies from the south basin of Lake Turkana), which record temperatures near the oxycline, may provide a new approach to estimating past temperature variability along a vertical profile in lakes, thereby providing information on water column mixing regimes. Our approach greatly expands our toolkit for understanding coupled climate seasonality and variability in the Turkana Basin. • Stable isotope sclerochronology combined with clumped stable isotopes on bivalve shells from the Turkana Basin (Africa) show changes in catchment precipitation and runoff seasonality during the Quaternary • Oxygen isotopic records from Late Holocene bivalve shells are more variable than those in a modern bivalve, however reconstructed lake water temperatures are comparable to modern lake water. • Records from Middle Holocene shells suggest reduced lake water physicochemical seasonality, with fresher water than modern. • Early Pleistocene bivalve fossil isotope geochemistry indicates enhanced seasonality in riverine runoff in a deltaic setting, and cooler than modern water temperatures. • Methods developed in this study combining clumped isotopes from littoral carbonates with TEX86 measurements from contemporaneous sediments deposited in deeper waters provide a model for future reconstructions of variations in vertical temperature profiles in paleolakes. [ABSTRACT FROM AUTHOR]

Abstract The California Current System (CCS) has two independent seasonal modes of upwelling variability, summer and winter, driven by different atmospheric processes. The variability of upwelling winds during winter is particularly important as strong, episodic events, driven by atmospheric teleconnections with the equatorial Pacific that are active in this season, impact ecological systems along the west coast of North America. Given the importance of upwelling seasonality to ecosystem function, we hypothesize that the Benguela Current System (BCS) shows similar independent seasonal modes of upwelling variability. To test this hypothesis, compare modes of variability between systems, and investigate potential drivers, we use an upwelling index derived from NCEP2 wind data (1979–2014) for the northern, southern, and Agulhas Bank areas of the BCS. In the northern and southern BCS, only one mode of upwelling variability is observed: year-round in the north and during the austral spring and summer (October through April) in the south. The Agulhas Bank region shows two modes of seasonal variability. Based on this 35-year dataset, summer upwelling modes in both the CCS and BCS appear to have similar decadal-scale variability. The other modes of variability (winter mode in the CCS and the non-seasonal second mode in the BCS) are correlated with year-to-year variability in the positioning of regional oceanic high-pressure systems. The leading mode of upwelling variability in the Agulhas Bank region, in the austral summer/fall, is highly correlated with sea level pressure as well as sea surface temperature in the equatorial Pacific, in a spatial and seasonal pattern (boreal winter) resembling the El Niño-Southern Oscillation. Across the CCS, modes of upwelling variability are similar to one another, while modes differ between regions in the BCS. This difference could lead to regional mismatches in favorable ecological conditions. In contrast with the spatially synchronous winter variability influencing the entire CCS ecosystem, substantial regional variation in the BCS may have strong effects on ecosystem functions, especially for species (e.g., small pelagic fish) that migrate between the Agulhas Bank and other areas of the BCS. Highlights • One dominant mode of upwelling variability in the BCS, two in Agulhas Bank and CCS • BCS modes show regional differences in seasonality, CCS modes are similar regionally. • CCS winter mode and Agulhas Bank first mode relate to high-pressure system latitude. • Agulhas Bank first mode is correlated to variability in the equatorial Pacific. • Summer upwelling modes in both systems show similar decadal variability. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to analyze and predict the thermal deformation of the through silicon via (TSV) interposer package during the manufacturing process and to perform a parametric study to minimize the warpage and thermal stress. Samples were selected during different stages of the assembly to observe the thermal behavior change. The Digital Image Correlation (DIC) technique was employed to measure the real-time deformation of the samples under thermal loading. To make a finite element analysis (FEA) model, material properties were characterized by DIC and Dynamic Mechanical Analysis (DMA). Based on the material properties and deformation data determined by experiments, a validated FEA model was established. To reduce the modeling complexity and the computing time in the simulation, the C4/underfill layer, micro bump/underfill layer, and TSV interposer were assumed to be isotropic. The most effective material properties for the isotropic layers were calculated by the composite theory. Also, the simulation followed the sequential manufacturing processes to investigate the thermal deformation change of each step and to obtain a more accurate prediction result. The thermal behavior from simulation showed a good agreement with the experimental result and this verified simulation model was implemented for the parametric study. A series of simulations were carried out to minimize the package warpage. To avoid any delamination failures, the stresses at the interface between the interposer and underfill were also evaluated. The effect of the interposer underfill material property, substrate material property, substrate thickness, and TSV density (Cu volume fraction) in the interposer were studied. It has been shown that low modulus, low coefficient of thermal expansion (CTE), and high glass transition temperature ( T g ) underfill, as well as a low modulus and low CTE substrate can mitigate the package warpage and stress development at the interface between interposer and underfill. Also, a larger Cu volume TSV interposer and thick substrate can lessen the warpage of the package and stress at the interface. [ABSTRACT FROM AUTHOR]

• Growth rings in two Pacific Arctic marine bivalves are annual and robustly delineated. • Growth rings were crossdated to form multi-decadal length chronologies. • Bivalves grew faster in warmer years with less sea ice. • These bivalves can generate long-term ecological baselines in the Pacific Arctic. The Pacific Arctic region has experienced, and is projected to continue experiencing, rapid climate change. Large uncertainties exist in our understanding of the impact these physical changes have on the region's ecology. This is, in part, due to the lack of long-term data. Here we investigate bivalve mollusc growth increment width chronologies (sclerochronologies) to develop a long-term biological data series in an Arctic species and address the hypothesis that benthic production in the Pacific Arctic region is in decline with implications for predators (e.g., walrus, whales, seals, and sea ducks). Growth increments formed in the shells of two bivalve mollusc species, Astarte borealis and Liocyma fluctuosa, were examined using conventional sclerochronological techniques. The A. borealis and L. fluctuosa samples exhibited measured longevities of >148 and >18 years, respectively, in the coastal waters of Alaska's Chukchi Sea. Dendrochronology crossdating techniques facilitated the development of two robust (expressed population signal > 0.85) independent growth increment width chronologies. These chronologies provide evidence of the growth conditions through time for each species (1985–2015 for A. borealis and 1997–2014 for L. fluctuosa). Linear regression analyses identified that both species grew more rapidly in years with warmer sea surface temperature and lower sea ice concentration. The results provide evidence that benthic ecosystems are benefiting from the warmer conditions and reduced sea ice that have accompanied recent Arctic climate trends. This result is encouraging for benthic predators in the eastern Chukchi Sea as it alleviates the concern that their benthic prey has already become food limited by weakened pelagic-benthic coupling. More broadly, this initial A. borealis chronology is among the longest biological data series for any Arctic species and highlights the feasibility of multicentennial biological data for the Arctic. [ABSTRACT FROM AUTHOR]

Abstract: Upwelling in eastern boundary current systems is a primary driver of ecosystem productivity. Typically, peak upwelling occurs during spring and summer, but winter upwelling may also be important to ecosystem functions. In this study, we investigated the hypothesis that winter and spring/summer upwelling, operating through indirect trophic interactions, are important to a suite of top predators in the California Current. To test this hypothesis, we collated information on upwelling, chlorophyll-a concentrations, zooplankton and forage fish, and related these to predator responses including rockfish growth, salmon abundance, seabird productivity and phenology (timing of egg-laying), and whale abundance. Seabird diets served in part as food web indicators. We modeled pathways of response using path analysis and tested for significance of the dominant paths with multiple regression. We found support for the hypothesis that relationships between upwelling and top predator variables were mediated primarily by intermediate trophic levels. Both winter and summer upwelling were important in path models, as were intermediate lower and mid trophic level functional groups represented by chlorophyll-a, zooplankton, and forage fish. Significant pathways of response explained from 50% to 80% of the variation of seabird (Cassin’s auklet (Ptychoramphus aleuticus) and common murre (Uria aalge)), humpback whale (Megaptera novaeangliae) and Chinook salmon (Oncorhynchus tshawytscha) dependent variables, whereas splitnose rockfish (Sebastes diploproa) showed no significant response pathways. Upwelling and trophic responses for salmon were established for both the year of ocean entry and the year of return, with zooplankton important in the year of ocean entry and forage fish important in the year of return. This study provides one of the first comparative investigations between upwelling and predators, from fish to marine mammals and birds within a geographically restricted area, demonstrates often difficult to establish “bottom-up” trophic interactions, and establishes the importance of seasonality of upwelling to various trophic connections and predator demographic traits. Understanding change in the seasonality of upwelling is therefore required to assess dynamics of commercially and recreationally important upper trophic level species in eastern boundary current ecosystems. [Copyright &y& Elsevier]

Polymer toughness is preserved at chronic timepoints in a new class of modulus-changing bioelectronics, which hold promise for commercial chronic implant components such as spinal cord stimulation leads. The underlying ester-free chemical network of the polymer substrate enables device rigidity during implantation, soft, compliant, conforming structures during acute phases in vivo, and gradual stabilization of materials properties chronically, maintaining materials toughness as device stiffness changes. In the past, bioelectronics device designs generally avoided modulus-changing and materials due to the difficulty in demonstrating consistent, predictable performance over time in the body. Here, the acute, and chronic mechanical and chemical properties of a new class of ester-free bioelectronic substrates are described and characterized via accelerated aging at elevated temperatures, with an assessment of their underlying cytotoxicity. Furthermore, spinal cord stimulation leads consisting of photolithographically-defined gold traces and titanium nitride (TiN) electrodes are fabricated on ester-free polymer substrates. Electrochemical properties of the fabricated devices are determined in vitro before implantation in the cervical spinal cord of rat models and subsequent quantification of device stimulation capabilities. Preliminary in vivo evidence demonstrates that this new generation of ester-free, softening bioelectronics holds promise to realize stable, scalable, chronically viable components for bioelectronic medicines of the future. [ABSTRACT FROM AUTHOR]