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Purpose: This study collected measures of auditory-perceptual and oral somatosensory acuity in typically developing children and adolescents aged 9–15 years. We aimed to establish reference data that can be used as a point of comparison for individuals with residual speech sound disorder (RSSD), especially for RSSD affecting American English rhotics. We examined concurrent validity between tasks and hypothesized that performance on at least some tasks would show a significant association with age, reflecting ongoing refinement of sensory function in later childhood. We also tested for an inverse relationship between performance on auditory and somatosensory tasks, which would support the hypothesis of a trade-off between sensory domains. Method: Ninety-eight children completed three auditory-perceptual tasks (identification and discrimination of stimuli from a “rake”–“wake” continuum and category goodness judgment for naturally produced words containing rhotics) and three oral somatosensory tasks (bite block with auditory masking, oral stereognosis, and articulatory awareness, which involved explicit judgments of relative tongue position for different speech sounds). Pairwise associations were examined between tasks within each domain and between task performance and age. Composite measures of auditory-perceptual and somatosensory functions were used to investigate the possibility of a sensory trade-off. Results: Statistically significant associations were observed between the identification and discrimination tasks and the bite block and articulatory awareness tasks. In addition, significant associations with age were found for the category goodness and bite block tasks. There was no statistically significant evidence of a trade-off between auditory-perceptual and somatosensory domains. Conclusions: This study provided a multidimensional characterization of speech-related sensory function in older children/adolescents. Complete materials to administer all experimental tasks have been shared, along with measures of central tendency and dispersion for scores in two subgroups of age. Ultimately, we hope to apply this information to make customized treatment recommendations for children with RSSD based on sensory profiles.

Studies examining sensorimotor adaptation of speech to changing sensory conditions have demonstrated a central role for both auditory and somatosensory feedback in speech motor learning. The potential influence of visual feedback of oral articulators, which is not typically available during speech production but may nonetheless enhance oral motor control, remains poorly understood. The present study explores the influence of ultrasound visual feedback of the tongue on adaptation of speech production (focusing on the sound /s/) to a physical perturbation of the oral articulators (prosthesis altering the shape of the hard palate). Two visual feedback groups were tested that differed in the two-dimensional plane being imaged (coronal or sagittal) during practice producing /s/ words, along with a no-visual-feedback control group. Participants in the coronal condition were found to adapt their speech production across a broader range of acoustic spectral moments and syllable contexts than the no-feedback controls. In contrast, the sagittal group showed reduced adaptation compared to no-feedback controls. The results indicate that real-time visual feedback of the tongue is spontaneously integrated during speech motor adaptation, with effects that can enhance or interfere with oral motor learning depending on compatibility of the visual articulatory information with requirements of the speaking task.

Current models of second language (L2) acquisition focus on interactions with a first language (L1) at the level of speech sound targets. In multilinguals, the degree of interaction between the articulatory plans that guide speech in each language remains unclear. Here, we directly address this question in bilingual speakers. We use a sensorimotor adaptation paradigm to drive the acquisition of novel articulatory plans for speech in one language and then measure the extent to which these new motor plans influence articulatory plans in the speaker's other language. Twenty L1-French, L2-English bilinguals adapted their speech production to a real-time alteration of vowel sounds. In one session, the adaptation was acquired during French sentence production; in a second session, the adaptation was acquired during English sentence production. In each session, cross-language transfer of these novel articulatory plans for speech was assessed using a transfer task that involved the production of French and English words with heavily noise-masked auditory feedback. Sensorimotor adaptation that countered the vowel sound alteration was observed in both French and English. Regardless of the linguistic context in which the adaptation was acquired, the adaptation transferred to the production of words in both languages. The amount of transfer did not depend on whether the adaptation was acquired in the participant's L1 or L2. In a second experiment, the result was replicated with twenty L1-English, L2-French speakers. The experiments support the idea that, in bilinguals, the interaction between L1 and L2 articulatory motor plans is rapid and bidirectional.

Perceiving the sensory consequences of our actions with a delay alters the interpretation of these afferent signals and impacts motor learning. For reaching movements, delayed visual feedback of hand position reduces the rate and extent of visuomotor adaptation, but substantial adaptation still occurs. Moreover, the detrimental effect of visual feedback delay on reach motor learning—selectively affecting its implicit component—can be mitigated by prior habituation to the delay. Auditory-motor learning for speech has been reported to be more sensitive to feedback delay, and it remains unknown whether habituation to auditory delay reduces its negative impact on learning. We investigated whether 30 minutes of exposure to auditory delay during speaking (a) affects the subjective perception of delay, and (b) mitigates its disruptive effect on speech auditory-motor learning. During a speech adaptation task with real-time perturbation of vowel spectral properties, participants heard this frequency-shifted feedback with no delay, 75 ms delay, or 115 ms delay. In the delay groups, 50% of participants had been exposed to the delay throughout a preceding 30-minute block of speaking whereas the remaining participants completed this block without delay. Although habituation minimized awareness of the delay, no improvement in adaptation to the spectral perturbation was observed. Thus, short-term habituation to auditory feedback delays is not effective in reducing the negative impact of delay on speech auditory-motor adaptation. Combined with previous findings, the strong negative effect of delay and the absence of an influence of delay awareness suggest the involvement of predominantly implicit learning mechanisms in speech.HIGHLIGHTSSpeech auditory-motor adaptation to a spectral perturbation was reduced by ~50% when feedback was delayed by 75 or 115 ms.Thirty minutes of prior delay exposure without perturbation effectively reduced participants’ awareness of the delay.However, habituation was ineffective in remediating the detrimental effect of delay on speech auditory-motor adaptation.The dissociation of delay awareness and adaptation suggests that speech auditory-motor learning is mostly implicit.

Processes controlling dissolved barium (dBa) were investigated along the GEOTRACES GA03 North Atlantic and GP16 Eastern Tropical Pacific transects, which traversed similar physical and biogeochemical provinces. Dissolved Ba concentrations are lowest in surface waters (∼35–50 nmol kg⁻¹) and increase to 70–80 and 140–150 nmol kg⁻¹ in deep waters of the Atlantic and Pacific transects, respectively. Using water mass mixing models, we estimate conservative mixing that accounts for most of dBa variability in both transects. To examine nonconservative processes, particulate excess Ba (pBa_(xs)) formation and dissolution rates were tracked by normalizing particulate excess ²³⁰Th activities. Th-normalized pBa_(xs) fluxes, with barite as the likely phase, have subsurface maxima in the top 1,000 m (∼100–200 μmol m⁻² year⁻¹ average) in both basins. Barite precipitation depletes dBa within oxygen minimum zones from concentrations predicted by water mass mixing, whereas inputs from continental margins, particle dissolution in the water column, and benthic diffusive flux raise dBa above predications. Average pBa_(xs) burial efficiencies along GA03 and GP16 are ∼37% and 17%–100%, respectively, and do not seem to be predicated on barite saturation indices in the overlying water column. Using published values, we reevaluate the global freshwater dBa river input as 6.6 ± 3.9 Gmol year⁻¹. Estuarine mixing processes may add another 3–13 Gmol year⁻¹. Dissolved Ba inputs from broad shallow continental margins, previously unaccounted for in global marine summaries, are substantial (∼17 Gmol year⁻¹), exceeding terrestrial freshwater inputs. Revising river and shelf dBa inputs may help bring the marine Ba isotope budget more into balance.

Early studies revealed relationships between barium (Ba), particulate organic carbon and silicate, suggesting applications for Ba as a paleoproductivity tracer and as a tracer of modern ocean circulation. But, what controls the distribution of barium (Ba) in the oceans? Herein, we investigated the Arctic Ocean Ba cycle through a one-of-a-kind data set containing dissolved (dBa), particulate (pBa), and stable isotope Ba ratio (δ138Ba) data from four Arctic GEOTRACES expeditions conducted in 2015. We hypothesized that margins would be a substantial source of Ba to the Arctic Ocean water column. The dBa, pBa, and δ138Ba distributions all suggest significant modification of inflowing Pacific seawater over the shelves, and the dBa mass balance implies that ∼50% of the dBa inventory (upper 500 m of the Arctic water column) was supplied by nonconservative inputs. Calculated areal dBa fluxes are up to 10 µmol m-2 d-1 on the margin, which is comparable to fluxes described in other regions. Applying this approach to dBa data from the 1994 Arctic Ocean Survey yields similar results. The Canadian Arctic Archipelago did not appear to have a similar margin source; rather, the dBa distribution in this section is consistent with mixing of Arctic Ocean-derived waters and Baffin Bay-derived waters. Although we lack enough information to identify the specifics of the shelf sediment Ba source, we suspect that a sedimentary remineralization and terrigenous sources (e.g., submarine groundwater discharge or fluvial particles) are contributors. Plain Language Summary We investigated the barium cycle in the Arctic Ocean. The oceanic barium cycle is supported by the interplay of seawater mixing, river inputs, sediment inputs, and particle formation and export from the water column. We determined that the distribution of dissolved barium in the upper 500 m of the Arctic Ocean is largely set by a shelf sediment source; this is newly described, as previous literature assumed rivers and seawater mixing were the predominant contributors to the distribution. This discovery fits in with recent findings that the shelf sediments are a major source of radium and other trace metals to the surface Arctic Ocean. This is important to consider as the warming climate continues to erode Arctic ice cover (sea ice or glacial). Monitoring the relative sources of Ba to the water column can help define how warming impacts Arctic Ocean biogeochemistry.

While recent research suggests that visual biofeedback can facilitate speech production training in clinical populations and second language (L2) learners, individual learners' responsiveness to biofeedback is highly variable. This study investigated the hypothesis that the type of biofeedback provided, visual-acoustic versus ultrasound, could interact with individuals' acuity in auditory and somatosensory domains. Specifically, it was hypothesized that learners with lower acuity in a sensory domain would show greater learning in response to biofeedback targeting that domain. Production variability and phonological awareness were also investigated as predictors. Sixty female native speakers of English received 30 min of training, randomly assigned to feature visual-acoustic or ultrasound biofeedback, for each of two Mandarin vowels. On average, participants showed a moderate magnitude of improvement (decrease in Euclidean distance from a native-speaker target) across both vowels and biofeedback conditions. The hypothesis of an interaction between sensory acuity and biofeedback type was not supported, but phonological awareness and production variability were predictive of learning gains, consistent with previous research. Specifically, high phonological awareness and low production variability post-training were associated with better outcomes, although these effects were mediated by vowel target. This line of research could have implications for personalized learning in both L2 pedagogy and clinical practice.

Purpose Previous work has found that both young and older adults exhibit a lexical bias in categorizing speech stimuli. In young adults, this has been argued to be an automatic influence of the lexicon on perceptual category boundaries. Older adults exhibit more top-down biases than younger adults, including an increased lexical bias. We investigated the nature of the increased lexical bias using a sensorimotor adaptation task designed to evaluate whether automatic processes drive this bias in older adults. Method A group of older adults ( n = 27) and younger adults ( n = 35) participated in an altered auditory feedback production task. Participants produced target words and nonwords under altered feedback that affected the 1st formant of the vowel. There were 2 feedback conditions that affected the lexical status of the target, such that target words were shifted to sound more like nonwords (e.g., less-liss ) and target nonwords to sound more like words (e.g., kess-kiss ). Results A mixed-effects linear regression was used to investigate the magnitude of compensation to altered auditory feedback between age groups and lexical conditions. Over the course of the experiment, older adults compensated (by shifting their production of 1st formant) more to altered auditory feedback when producing words that were shifted toward nonwords ( less-liss ) than when producing nonwords that were shifted toward words ( kess-kiss ). This is in contrast to younger adults who compensated more to nonwords that were shifted toward words compared to words that were shifted toward nonwords. Conclusion We found no evidence that the increased lexical bias previously observed in older adults is driven by a greater sensitivity to top-down lexical influence on perceptual category boundaries. We suggest the increased lexical bias in older adults is driven by postperceptual processes that arise as a result of age-related cognitive and sensory changes.

Introduction/Objective Advances in precision medicine necessitate a closer integration across pathologists, genetic counselors, and other members of the multidisciplinary cancer care team (MDT). Recognizing that physical distancing and fragmented communication may hinder care delivery, the Association of Community Cancer Centers (ACCC) ran a multi-year initiative to explore ways to improve MDT care coordination. Methods/Case Report ACCC held a multistakeholder leadership summit to identify and discuss critical issues regarding biomarker and hereditary genetic testing and the ways in which pathology and genetic counseling professionals interface with the cancer MDT. Through a consensus-driven process, participants identified key opportunities for achieving optimal integration. ACCC also conducted a national survey to explore barriers around biomarker and hereditary genetic testing. Building off these insights, ACCC conducted virtual workshops at three community cancer programs to improve processes around biomarker testing and targeted treatment planning. Results (if a Case Study enter NA) The pathology leadership summit identified the following priorities: 1) streamline and standardize the biomarker test ordering process; 2) improve tissue handling to optimize timely biomarker testing; 3) strengthen communication between pathologists and genetic counselors; 4) empower pathologists with leadership opportunities. In the ACCC survey (n=659), 57% indicated that some or most of their pathologists were generalists. 21% only held one general tumor board. 6% indicated that pathologists often do not attend tumor boards or cancer committee meetings. 64% indicated that pathologists can directly access some or all medical oncology patient records. 67% sent some or most biopsy samples out for biomarker testing. In the ACCC workshops, cancer programs in KS, NC, and NV identified ways to improve the timeliness of genetic counseling referrals and coordinate biomarker testing. Following the workshops, 64% indicated they planned to make moderate or significant changes in their processes. Conclusion Improving collaboration across pathologists, genetic counselors, and the rest of the cancer MDT may lead to more timely and comprehensive biomarker and hereditary genetic testing. These findings may help cancer programs refine processes of care.

International audience; The Mississippi Bight, east of the Mississippi River, is a complex coastal ecosystem that, like the better-known Louisiana Shelf to the west, experiences seasonal bottom water hypoxia. However, input of allochthonous nutrients from the Mississippi River to the Mississippi Bight appears to be limited, begging the question of what drives seasonal hypoxia in this system. Prior research has suggested submarine groundwater discharge (SGD) could be an overlooked component of the Mississippi Bight biogeochemical system. We thus examined the hypothesis that SGD provides a "bottom up" driver for seasonal hypoxia in this area. We used a multi-tracer approach based on known SGD indicators (dissolved Ra, Ba, Si, methane) to: i) demonstrate the presence of SGD as a constituent contributor to Bight bottom waters, ii) constrain the SGD flux of macronutrients, and, iii) investigate the hypoxia-SGD linkage. We found excess SGD tracers in saline bottom waters relative to surface waters, suggesting a bottom source. Examination of other sources for the constituent enrichments besides SGD (e. g., rivers, produced waters from oil wells) appear inadequate to close the bottom water chemical mass balances. Additionally, inverse correlations between DO and SGD indicators in bottom waters support a common mechanism supplying dissolved Ra, Ba, and Si, and decreasing DO concentrations in these waters. Two different approaches to modeling the bottom water Ra distribution both suggest a seepage rate of ~0.055 m 3 m − 2 d − 1 , in line with previous estimates in similar systems. Our more complex model, involving four mass balances, suggests that as much as 10-20% of the bottom water in the Bight circulates through the underlying permeable sediments on a time scale of ~10 days. This circulated water emerges as SGD with completely altered chemistry. More specifically, SGD appears in some cases to be the dominant contributor of nutrients to Bight bottom waters. Additionally, the potential oxygen demand of reduced species within SGD likely contributes significantly to the development of seasonal hypoxia in Bight bottom waters. Further work is needed to better resolve sources of nutrients and additional reduced species within the Mississippi Bight SGD as well as the variability and pathways of this supply. Nonetheless, the bottom-up influence of SGD on the Mississippi Bight appears to be a significant and overlooked aspect of this system. We suggest that such a bottom-up influence may be a generally important feature of coastal ecosystems.

25 pages, 11 figures, supporting information https://doi.org/10.1029/2020GB006769.-- Data Availability Statement: The new and compiled data reported here are available at the NOAA Paleoclimatology database (https://www.ncdc.noaa.gov/paleo/study/30512), Quantitative knowledge about the burial of sedimentary components at the seafloor has wide‐ranging implications in ocean science, from global climate to continental weathering. The use of 230Th‐normalized fluxes reduces uncertainties that many prior studies faced by accounting for the effects of sediment redistribution by bottom currents and minimizing the impact of age model uncertainty. Here we employ a recently compiled global data set of 230Th‐normalized fluxes with an updated database of seafloor surface sediment composition to derive atlases of the deep‐sea burial flux of calcium carbonate, biogenic opal, total organic carbon (TOC), nonbiogenic material, iron, mercury, and excess barium (Baxs). The spatial patterns of major component burial are mainly consistent with prior work, but the new quantitative estimates allow evaluations of deep‐sea budgets. Our integrated deep‐sea burial fluxes are 136 Tg C/yr CaCO3, 153 Tg Si/yr opal, 20Tg C/yr TOC, 220 Mg Hg/yr, and 2.6 Tg Baxs/yr. This opal flux is roughly a factor of 2 increase over previous estimates, with important implications for the global Si cycle. Sedimentary Fe fluxes reflect a mixture of sources including lithogenic material, hydrothermal inputs and authigenic phases. The fluxes of some commonly used paleo‐productivity proxies (TOC, biogenic opal, and Baxs) are not well‐correlated geographically with satellite‐based productivity estimates. Our new compilation of sedimentary fluxes provides detailed regional and global information, which will help refine the understanding of sediment preservation, This study was supported by the Past Global Changes (PAGES) project, which in turn received support from the Swiss Academy of Sciences and the US‐NSF. The work grew out of a 2018 workshop in Aix‐Marseille, France, funded by PAGES, GEOTRACES, SCOR, US‐NSF, Aix Marseille Université, and John Cantle Scientific, and the authors would like to acknowledge all attendees of this meeting. [...]. Christopher T. Hayes acknowledges support from US‐NSF awards 1658445 and 1737023. Some data compilation on Arctic shelf seas was supported by the Russian Science Foundation, grant number 20‐17‐00157. This work was also supported through project CRESCENDO (grant no. 641816, European Commission). Zanna Chase acknowledges support from the Australian Research Council’s Discovery Projects funding scheme (project DP180102357). Christopher R. German acknowledges US‐NSF awards 1235248 and 1234827, With the funding support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S), of the Spanish Research Agency (AEI)

A multi-year (2007–2011) chemical time series of eight stations in the western Mississippi Sound and northwestern Mississippi Bight was undertaken to examine the factors affecting chemical distributions in this dynamic region. Parameters measured include nutrients and selected dissolved trace elements (Ba, Cr, Cs, Fe, Mn, Mo, Re, U, and V). Key findings include the frequent development of bottom water hypoxia in this part of the Bight during late spring and summer, the likely contribution of submarine groundwater discharge (SGD) to the material flows (i.e., Ba, V and nutrients), and the effects of episodic events (i.e., tropical storms, cold fronts, the opening of the Bonnet Carre Spillway) on trace element distributions. In hypoxic bottom waters, enriched nutrients, Mn, and Ba as well as depleted V and Cr were commonly observed. Although dissolved Mn was often enriched to micromolar levels in hypoxic bottom waters, Fe (both dissolved and colloidal) was rarely over 100 nM, likely due to its rapid oxidation and removal. Similar to previous observations in Louisiana Shelf waters, the signal of bottom depletion of V and Cr during hypoxia is at times mixed upwards into surface waters. Consideration of the mass balances of dissolved Ba and V, in particular, supports the conclusion that SGD can be a significant contributor to the chemical mass balance in this region, not just for certain trace elements, but for nutrients, too. Interestingly, a seasonal change in the direction of the V flux from the sediments suggests that the chemical conditions (i.e., pH, EH, and/or DOC) of the groundwater are changing. During the study period, the Bonnet Carre Spillway was opened in April 2008 and May 2011. The spillway discharges Mississippi River to Lake Pontchartrain and ultimately to our study area, which is supported by the observation of an extended freshwater signal and low Cs across the Mississippi Sound and Bight during these two spillway openings. It is plausible that Mississippi Bight hypoxia was more severe due to increased nutrients and intense stratification induced by Mississippi River input following the opening of Bonnet Carre Spillway. Other episodic events included tropical storms, which can push Mississippi River water northward and make this material source potentially more important at those times. Important remaining questions from this study include the extent to which SGD and/or Mississippi River water are necessary for establishment and maintenance of hypoxia in the Mississippi Bight and the reasons for the seasonal change in the direction of the sedimentary V flux.

Data collected during the US Arctic GEOTRACES expedition in 2015 are used to estimate the mean residence time of dissolved trace elements (Fe, Mn, Ni, Cd, Zn, Cu, Pb, V) in surface water with respect to atmospheric deposition . The calculations utilize mixed layer trace element (TE) inventories, aerosol solubility determinations, and estimates of the atmospheric trace element flux into the upper ocean. The trace element flux is estimated by the product of the 7Be flux (determined by the ocean 7Be inventory) and the TE/7Be ratio of aerosols. This method has been established elsewhere and is tested here by comparing 7Be-derived TE flux to the measured TE accumulation in recently deposited snow. Given the variability in snow and aerosol TE concentration observed over the expedition, and the limited timescale of the observations, agreement between the two methods is reasonable. While there are assumptions in these calculations, the distribution of residence times with respect to atmospheric input across the expedition track informs us of additional sources or sinks for each element. The residence time of dissolved Fe was ~ 20–40 y for most stations. However, several stations that display a longer, oceanographically inconsistent apparent Fe residence time of ~300–500 years are likely influenced by additional input from the Transpolar Drift (TPD), which has been shown to convey shelf water properties to the central Arctic. This was seen for Cu, Ni and Zn as well. The flux of Fe delivered by the TPD was ~ 10 nmol/m2 /d for these stations, an order of magnitude greater than the soluble atmospheric input. On the other hand, V and Pb show a decrease in the apparent residence times within TPD water, suggesting removal of these elements from the source region of the TPD. For Mn, there is no obvious trend in residence time among the stations; however the apparent residence time (400–1400 y) is significantly greater than the ~20 y calculated for atmospheric input elsewhere, signifying appreciable input from other sources. It has been suggested that about 90% of Mn input to the Arctic Ocean originates from Arctic rivers, shelf sediments , and coastal erosion. Results here suggest a flux from these sources of ~30 nmol/m 2/d which is significantly greater than the atmospheric input of Mn in the Arctic.

Melt ponds are a prominent feature of Arctic sea ice during the summer and play a role in the complex interface between the atmosphere, cryosphere and surface ocean. During melt pond formation and development, micronutrient and contaminant trace elements (TEs) from seasonally accumulated atmospheric deposition are mixed with entrained sedimentary and marine-derived material before being released to the surface ocean during sea ice melting. Here we present particulate and size-fractionated dissolved (truly soluble and colloidal) TE data from five melt ponds sampled in late summer 2015, during the US Arctic GEOTRACES (GN01) cruise. Analyses of salinity, δ18O, and 7Be indicate variable contributions to the melt ponds from snowmelt, melting sea ice, and surface seawater. Our data highlight the complex TE biogeochemistry of late summer Arctic melt ponds and the variable importance of different sources for specific TEs. Dissolved TE concentrations indicate a strong influence from seawater intrusion for V, Ni, Cu, Cd, and Ba. Ultrafiltration methods reveal dissolved Fe, Zn, and Pb to be mostly colloidal (0.003–0.2 μm), while Mn, Co, Ni, Cu, and Cd are dominated by a truly soluble (

Salt marsh sediments generally undergo steady accumulation over time and thus are widely used to reconstruct the depositional histories of various anthropogenic contaminants derived from atmospheric and fluvial sources. Major hurricanes can significantly affect coastal landscapes by eroding and re-distributing sediment. Thus, each major hurricane can leave distinct signals in coastal wetland sediments. On the other hand, early-diagenetic remobilization of Fe and Mn in organic rich marsh sediment is a common phenomenon. However, remobilization of Fe and Mn across the redox boundary can induce remobilization of other trace elements and thus can disturb their depositional histories. Four short (~1m) sediment cores were collected from the fringing marshes of St. Louis Bay, Mississippi (located ~30km east of Hurricane Katrina's track) during 2010-2011 to investigate possible impacts of Hurricane Katrina (2005), and early-diagenetic remobilization of Fe and Mn, on trace metal and dioxin depositional histories in these sediments. Results from 210Pb, 137Cs, stable Cs, particulate organic carbon (POC), sediment bulk density and grain size indicate significant impact of hurricane event layers on anthropogenic stable Cs, while deposition profiles of V, Ni and Cr are impacted by Fe and Mn remobilization to a limited extent.

Estuarine-shelf exchange can drive strong gradients in physical and biogeochemical properties in the coastal zone and exert a significant influence on biological processes and patterns. Physical, biogeochemical, and plankton data from an across-shelf transect extending south of Mobile Bay, Alabama, in conjunction with regional time series data, were used to determine the relative importance of estuarine-shelf interactions on the physical-biological structuring of the shelf environment during fall conditions (i.e., well-mixed, low discharge). This period was also characterized by a relatively unique weather event associated with the remnants of Hurricane Patricia, which drove a meteorological flushing of estuarine water onto the shelf. Survey data indicated generally low N:P ratios across the shelf, with slightly elevated dissolved inorganic nitrogen in the Region of Freshwater Influence (ROFI) that extended approximately 30 km offshore. The ROFI had higher values of chlorophyll-a, diatom-specific production, marine snow, and primary productivity, with notable contributions from the larger size cells (>5 µm). Furthermore, stratification provided a niche opportunity for Trichodesmium sp. aggregates , a typically oligotrophic cyanobacteria, at the offshore edge of the ROFI. The lens of estuarine water may have limited the vertical extent to which this population was mixed, providing enhanced light availability relative to the well-mixed offshore conditions. Following the biogeochemical trend, the highest zooplankton abundances were also located within the estuarine outflow. While limited in spatial extent, the distinct geochemical and biological characteristics within the ROFI demonstrate the ecological impacts that estuarine-sourced waters can have during periods of generally low productivity in the Mississippi Bight.

Data from GEOTRACES cruises GN01 (HLY1502) and GN04 (PS94) have been archived at the Biological & Chemical Oceanography Data Management Office (BCO-DMO; https://www.bco-dmo.org/deployment/638807) and PANGAEA (https://www.pangaea.de/?q=PS94&f.campaign%5B%5D=PS94) websites, respectively. The inorganic carbon data are available at the NOAA Ocean Carbon Data System (OCADS ; doi :10.3334/CDIAC/OTG.CLIVAR_ARC01_33HQ20150809). In addition to these national data archives, the data used in this paper is available as a supplementary downloadable excel file; International audience; A major surface circulation feature of the Arctic Ocean is the Transpolar Drift (TPD), a current that transports river‐influenced shelf water from the Laptev and East Siberian Seas toward the center of the basin and Fram Strait. In 2015, the international GEOTRACES program included a high‐resolution pan‐Arctic survey of carbon, nutrients, and a suite of trace elements and isotopes (TEIs). The cruises bisected the TPD at two locations in the central basin, which were defined by maxima in meteoric water and dissolved organic carbon concentrations that spanned 600 km horizontally and ~25‐50 m vertically. Dissolved TEIs such as Fe, Co, Ni, Cu, Hg, Nd, and Th, which are generally particle‐reactive but can be complexed by organic matter, were observed at concentrations much higher than expected for the open ocean setting. Other trace element concentrations such as Al, V, Ga, and Pb were lower than expected due to scavenging over the productive East Siberian and Laptev shelf seas. Using a combination of radionuclide tracers and ice drift modeling, the transport rate for the core of the TPD was estimated at 0.9 ± 0.4 Sv (106 m3 s‐1). This rate was used to derive the mass flux for TEIs that were enriched in the TPD, revealing the importance of lateral transport in supplying materials beneath the ice to the central Arctic Ocean and potentially to the North Atlantic Ocean via Fram Strait. Continued intensification of the Arctic hydrologic cycle and permafrost degradation will likely lead to an increase in the flux of TEIs into the Arctic Ocean.

International audience; The northern Gulf of Mexico is a complex and very productive coastal river-dominated system that receives freshwater from numerous rivers including the Mississippi River. The dynamics of coastal ecosystems in the northern Gulf of Mexico are greatly influenced by the freshwater discharge but also by the high nutrient loads carried by the Mississippi River that lead to the seasonal development of one of the largest coastal hypoxic areas. Constraining the origin and fate of the freshwater inputs in the northern Gulf of Mexico will help increase understanding the physical and biogeochemical processes occurring in this region. Here, we focus on investigating the extent of the Mississippi River plume on both sides of the Mississippi River Delta: to the east in the Mississippi Bight, and to the west over the Louisiana Shelf. We determined the water isotopic signature (δ 18 O and δD) along with salinity of the different river plumes and performed a river mixing model on the coastal waters. Our findings provide useful information to better understand the functioning of the northern Gulf of Mexico ecosystem. In particular, the development of hypoxia is often attributed to the nutrient load of the Mississippi River, yet the Mississippi River seemed to have a limited influence on the Mississippi Bight. That is, the dominant source of freshwater in the Bight was supplied by local Mississippi/Alabama rivers. Furthermore, the water isotope mixing model showed that the source of freshwater to the Louisiana Shelf was dominated by the Atchafalaya River in summer, and by the Mississippi River during non-summer seasons. This pattern is consistent with the general shelf circulation that reverses in summer, but could not have been shown solely by the use of salinity.

Stuttering is a disorder that impacts the smooth flow of speech production and is associated with a deficit in sensorimotor integration. In a previous experiment, individuals who stutter were able to vocally compensate for pitch shifts in their auditory feedback, but they exhibited more variability in the timing of their corrective responses. In the current study, we focused on the neural correlates of the task using functional MRI. Participants produced a vowel sound in the scanner while hearing their own voice in real time through headphones. On some trials, the audio was shifted up or down in pitch, eliciting a corrective vocal response. Contrasting pitch-shifted vs. unshifted trials revealed bilateral superior temporal activation over all the participants. However, the groups differed in the activation of middle temporal gyrus and superior frontal gyrus [Brodmann area 10 (BA 10)], with individuals who stutter displaying deactivation while controls displayed activation. In addition to the standard univariate general linear modeling approach, we employed a data-driven technique (independent component analysis, or ICA) to separate task activity into functional networks. Among the networks most correlated with the experimental time course, there was a combined auditory-motor network in controls, but the two networks remained separable for individuals who stuttered. The decoupling of these networks may account for temporal variability in pitch compensation reported in our previous work, and supports the idea that neural network coherence is disturbed in the stuttering brain.

The margin of the western North Pacific Ocean releases redox-active elements like Mn, Co, and Ce into the water column to undergo further transformation through oxide formation, scavenging, and reductive dissolution. Near the margin, the upper ocean waters enriched in these elements are characterized by high dissolved oxygen, low salinity, and low temperature, and are a source of the North Pacific Intermediate Water. High dissolved concentrations are observed across the Western Subarctic Gyre, with a rapid decrease in concentrations away from the margin and across the subarctic-subtropical front. The particulate concentrations of Mn, Co, and Ce are also high in the subarctic surface ocean and enriched relative to Ti and trivalent rare earth elements. Furthermore, the particles enriched in Mn, Co, and Ce coincide at the same depth range, suggesting that these elemental cycles are coupled through microbial oxidation in the subarctic gyre as the waters travel along the margin before being subducted at the subarctic-subtropical front. Away from the margin, the Mn, Co, and Ce cycles decouple, as Mn and Ce settle out as particles while dissolved Co is preserved and transported within the North Pacific Intermediate Water into the central North Pacific Ocean.

Speech timing deficits have been proposed as a causal factor in the disorder of stuttering. The question of whether individuals who stutter have deficits in nonspeech timing is one that has been revisited often, with conflicting results. Here, we uncover subtle differences in a manual metronome synchronization task that included tempo changes with adults who stutter and fluent speakers. We used sensitive circular statistics to examine both asynchrony and consistency in motor production. While both groups displayed a classic negative mean asynchrony (tapping before the beat), individuals who stutter anticipated the beat even more than their fluent peers, and their consistency was particularly affected at slow tempi. Surprisingly, individuals who stutter did not have problems with interval correction at tempo changes. We also examined the influence of music experience on synchronization behavior in both groups. While music perception and training were related to synchronization behavior in fluent participants, these correlations were not present for the stuttering group; however, one measure of stuttering severity (self-rated severity) was negatively correlated with music training. Overall, we found subtle differences in paced auditory–motor synchronization in individuals who stutter, consistent with a timing problem extending to nonspeech.

With our marine ecosystems under threat from climate change, there is an urgent need to continuously monitor marine conditions. One key indicator is the dissolved oxygen level, but existing sensors are limited by size and costs that preclude widespread non-intrusive monitoring. This work reports a new dual-gate design based on organic electrochemical transistors (OECTs) to track dissolved oxygen concentration in seawater, a highly challenging matrix owing to its high ionic strength and multitude of chemical interferents. We present the novel operating principle, by deriving the channel conductance with respect to potentials on the two gates. The sensor achieved a detection limit of 0.5 ppm dissolved oxygen concentration in seawater. The device demonstrated reliable operation over five days and was capable of monitoring oxygenation changes arising from the photosynthesis cycles of saltwater macro-algae.

Substantial work suggests that floodplain wetlands could play a role in modifying fluvial fluxes of dissolved and colloidal trace elements. Yet, few studies have directly addressed this issue. We examined trace elements in the East Pearl River (Mississippi/Louisiana, USA), which is surrounded by wetlands that are temporally more or less connected to the river depending on river stage. Dissolved and colloidal trace element samples, along with ancillary data, including dissolved organic carbon (DOC) and nutrients, were collected during eight surveys of this system at different flow stages from November 2007 to September 2008. Hydrology of the system is complex due to seasonal changes in water sources as well as potential inputs from the floodplain wetlands and the hyporheic zone. We therefore considered effects including non-conservative mixing of water sources, saltwater intrusion, and floodplain wetland flux requirements needed to support observed downstream concentration changes. During moderately high discharge, fluxes of many elements (e.g., Cd, Fe, Mn, Zn) increased downstream by 20% or more, with inputs from the floodplain wetlands as the apparent source. At the highest discharge, however, wetland inputs to the river may have been rate-limited (i.e., the wetland source was flushed faster than biogeochemical processes could regenerate dissolved/colloidal material). At low discharge, other effects, including saltwater intrusion and hyporheic zone interactions, are important. Both redox processes and organic ligands (or DOC), along with the supply of wetland inputs (or removal) relative to river fluxes, appear to be key factors determining floodplain wetland effects. While the behavior of some elements suggests they were dominantly affected by redox processes (Mn and V) or by organic complexation (dissolved Fe and light rare earths), other elements were affected by more than one process in ways that remain obscure (Cu). Overall our results are broadly consistent with previous field, laboratory and modeling studies and suggest that a better understanding of the sources and transformations of Fe is a key area for future research. This article is protected by copyright. All rights reserved.

The Banff Working Group on Liver Allograft Pathology reviewed and discussed literature evidence regarding antibody-mediated liver allograft rejection at the 11th (Paris, France, June 5-10, 2011), 12th (Comandatuba, Brazil, August 19-23, 2013), and 13th (Vancouver, British Columbia, Canada, October 5-10, 2015) meetings of the Banff Conference on Allograft Pathology. Discussion continued online. The primary goal was to introduce guidelines and consensus criteria for the diagnosis of liver allograft antibody-mediated rejection and provide a comprehensive update of all Banff Schema recommendations. Included are new recommendations for complement component 4d tissue staining and interpretation, staging liver allograft fibrosis, and findings related to immunosuppression minimization. In an effort to create a single reference document, previous unchanged criteria are also included.

To investigate the floodplain influence on carbon speciation and export to the northern Gulf of Mexico, water samples were collected monthly from two sites in the East Pearl River (EPR) basin during 2006–2008. Additionally, four spatial surveys in the river basin between those two sites were also conducted. Compared with the upstream sampling site at Bogalusa, MS, dissolved inorganic carbon (DIC) and particulate organic carbon (POC) concentrations were 36% and 55% lower, respectively, and dissolved organic carbon (DOC) concentration was 49% higher at the downstream Stennis Space Center (SSC) site. In addition, the bulk DOC pool at SSC had a higher colloidal fraction than at Bogalusa (75% vs. 68%). Detailed spatial surveys revealed the differences between the upstream and downstream stations resulted both from input from Hobolochitto Creek, a tributary of the EPR, and from influence of the swamp-rich floodplain. The contributions from Hobolochitto Creek to the carbon pool in the EPR basin were lowest during a high flow event and reached a maximum during the dry season. Meanwhile, the floodplain in the EPR basin acted as a significant sink for DOC, POC and particulate nitrogen during summer and for suspended sediment during a high flow event. However, the floodplain was converted into a source of suspended sediment, DOC, and POC to the EPR during winter, revealing a dynamic nature and seasonality in the floodplain influence. Consistent with its dominant forest coverage, abundant wetlands along the river corridor, and mild anthropogenic disturbance, the Pearl River basin above Bogalusa generally had higher yields of DOC and POC (1903 and 1386 kg-C km −2 yr −1 , respectively), but a lower yield of DIC (2126 kg-C km −2 yr −1 ) compared to other North American rivers. An estimation based on a mass balance approach suggests the interactions between floodplain and the main river stem could reduce the annual DIC and POC export fluxes from downstream of the EPR by 24% and 40%, respectively, but enhance the annual riverine DOC export by 25%. Similar scenarios likely occur in other wetland-rich coastal rivers and are capable of significantly altering the current estimation of riverine carbon export.

Flow field-flow fractionation (FlFFF) coupled on-line with UV absorbance and fluorescence detectors was used to examine the colloidal composition and size distribution of optically active dissolved organic matter (DOM) in the lower Mississippi River (MR), the East Pearl River (EPR), the St. Louis Bay (SLB) estuary, and coastal waters of the northern Gulf of Mexico. In addition to field studies, laboratory mixing experiments using river and seawater end-members were carried out to study the processes controlling the estuarine mixing behavior and size partitioning of colloids with different sizes and composition. The colloidal size spectra of chromophoric DOM and humic-like DOM showed one dominant peak in the 0.5–4 nm size range, representing >75% of the total FlFFF-recoverable colloids. In contrast, protein-like DOM showed a bi-modal distribution with peaks at 0.5–4 nm and 4–8 nm, as well as a major portion (from ∼41% in the EPR to ∼72% in the Mississippi Bight) partitioned to the >20 nm size fraction. Bulk DOM was lower in abundance and molecular-weight in the MR compared with the EPR, while the proportion of colloidal protein-like DOM in the >20 nm size range was slightly larger in the MR compared with the EPR. These features are consistent with differences in land use, hydrological conditions, and water residence time between the two river basins, with more autochthonous DOM in MR waters. In the SLB estuary, different DOM components demonstrated different mixing behaviors. The abundance of colloidal chromophoric DOM decreased with increasing salinity and showed evident removal during estuarine mixing even though the bulk DOM appeared to be conservative. In contrast, colloidal humic-like DOM behaved conservatively inside SLB and during laboratory mixing experiments. The ratio of colloidal protein-like to humic-like DOM generally increased with increasing salinity, consistent with increasing autochthonous protein-like DOM and removal of terrestrially-derived humic-like DOM in estuarine and coastal waters. Similar mixing behavior for the bulk DOM and colloids was observed in short-term laboratory mixing experiments, suggesting that physicochemical processes are the major controlling factor for colloidal removal in the estuary. For the first time, this study showed direct evidence of contrasting estuarine mixing behavior for different size fractions of optically active colloidal DOM.

Selected trace elements (TEs), dissolved organic carbon and nutrients were studied in Louisiana Shelf waters including the low salinity Mississippi (MR) and Atchafalaya (AR) River plumes during periods of high, intermediate and low river discharge in 2008–2009. The dissolved phase (