Core Site Research Articles

MERIDIONAL MIGRATIONS OF THE INTERTROPICAL CONVERGENCE ZONE DURING THE LAST DEGLACIATION IN THE TIMOR SEA DETECTED BY EXTENSIVE RADIOCARBON DATING

ABSTRACT At the Intertropical Convergence Zone (ITCZ), the northern and southern Tradewinds converge, and this region is characterized by low atmospheric pressure and high precipitation. The climate in the Timor Sea is characterized by seasonal precipitation changes driven by meridional migrations of the ITCZ and the monsoonal front. The ITCZ shifts in response to changes in the thermal balance between the northern and southern hemispheres. Thus, reconstruction of paleo-precipitation in the Timor Sea is expected to reveal past changes in both regional and global climate, the latter through inference of the ITCZ position. To reconstruct paleo-precipitation in the Timor Sea, we performed extensive radiocarbon analysis on both planktonic foraminifera and total organic carbon (TOC), which is derived from terrestrial and marine sources. Increased precipitation enhances the fraction of relatively old, terrestrial carbon to the core site, which in turn increases the difference between the ages of TOC and planktonic foraminifera. Variations in radiocarbon ages reveal that during northern hemisphere cooling intervals such as Heinrich Stadial 1 and the Younger Dryas, the ITCZ was in a southern position, thus increasing precipitation in the Timor Sea. However, the Timor Sea was dryer during the Bølling–Allerød warming as the ITCZ shifted northward.

Synchronous retreat of Thwaites and Pine Island glaciers in response to external forcings in the presatellite era

Today, relatively warm Circumpolar Deep Water is melting Thwaites Glacier at the base of its ice shelf and at the grounding zone, contributing to significant ice retreat. Accelerating ice loss has been observed since the 1970s; however, it is unclear when this phase of significant melting initiated. We analyzed the marine sedimentary record to reconstruct Thwaites Glacier's history from the early Holocene to present. Marine geophysical surveys were carried out along the floating ice-shelf margin to identify core locations from various geomorphic settings. We use sedimentological data and physical properties to define sedimentary facies at seven core sites. Glaciomarine sediment deposits reveal that the grounded ice in the Amundsen Sea Embayment had already retreated to within ~45 km of the modern grounding zone prior to ca. 9,400 y ago. Sediments deposited within the past 100+ y record abrupt changes in environmental conditions. On seafloor highs, these shifts document ice-shelf thinning initiating at least as early as the 1940s. Sediments recovered from deep basins reflect a transition from ice proximal to slightly more distal conditions, suggesting ongoing grounding-zone retreat since the 1950s. The timing of ice-shelf unpinning from the seafloor for Thwaites Glacier coincides with similar records from neighboring Pine Island Glacier. Our work provides robust new evidence that glacier retreat in the Amundsen Sea was initiated in the mid-twentieth century, likely associated with climate variability.

Switching Electrocatalytic Hydrogen Evolution Pathways through Electronic Tuning of Copper Porphyrins

AbstractThe electronic structure of metal complexes plays key roles in determining their catalytic features. However, controlling electronic structures to regulate reaction mechanisms is of fundamental interest but has been rarely presented. Herein, we report electronic tuning of Cu porphyrins to switch pathways of the hydrogen evolution reaction (HER). Through controllable and regioselective β‐oxidation of Cu porphyrin 1, we synthesized analogues 2–4 with one or two β‐lactone groups in either a cis or trans configuration. Complexes 1–4 have the same Cu‐N4 core site but different electronic structures. Although β‐oxidation led to large anodic shifts of reductions, 1–4 displayed similar HER activities in terms of close overpotentials. With electrochemical, chemical and theoretical results, we show that the catalytically active species switches from a CuI species for 1 to a Cu0 species for 4. This work is thus significant to present mechanism‐controllable HER via electronic tuning of catalysts.

PEGylated AIEgens for dual sensing of ATP and H2S and cancer cells photodynamic therapy

Fluorescent sensors have been widely applied for biosensing, but probes for both multiple analytes sensing and photodynamic therapy (PDT) effect are less reported. In this article, we reported three AIE-based probes anchored with different mass-weight polyethylene glycol (PEG) tails, i.e., TPE-PEG160, TPE-PEG350, and TPE-PEG750, for both adenosine-5′-triphosphate (ATP) and hydrogen sulfide (H2S) detection and also cancer cells photodynamic therapy. TPE-PEGns (n = 160, 350 and 750) contain the tetraphenylethylene-based fluorophore core, the pyridinium and amide anion binding sites, the H2S cleavable disulfide bond, and the hydrophilic PEG chain. They exhibit a good amphiphilic property and can self-assemble nona-aggregation with a moderated red emission in an aqueous solution. Importantly, the size of aggregation, photophysical property, sensing ability and photosensitivity of these amphiphilic probes can be controlled by tuning the PEG chain length. Moreover, the selected probe TPE-PEG160 has been successfully used to detect environmental H2S and image ATP levels in living cells, and TPE-PEG750 has been used for photodynamic therapy of tumor cells under light irradiation.

The influence of fluvial and glacial watershed dynamics on Holocene sediment accumulation in Cariboo Lake, Columbia Mountains, British Columbia, Canada

Records of sedimentation collected from Cariboo Lake, situated in the northern Columbia Mountains, British Columbia, Canada, are analyzed to assess Holocene fluvial and glacial watershed dynamics. The aim of this study is to provide a proxy record of Holocene hydroclimate and glacier change from sediment archives at a higher temporal resolution compared to available records for the Interior Ranges of British Columbia. Deglacial and Holocene sediment accumulation is observed to reach a maximum thickness of 35 m in deep parts of the lake, using sub-bottom acoustic soundings. A transition from massive to well-stratified sediments is observed in the sub-bottom acoustic record during final phases of valley deglaciation in the region (~10.5–9 cal ka BP). Laminae couplets are interpreted to be deposited annually according to two 14C dates and a varve counting chronology. Two long cores, 2.9 and 3.8 m in length, were selected for analysis with estimated basal dates of 2 cal ka BP. Trends in downcore sediment characteristics were linked to environmental changes in the glaciated catchment headwaters at a temporal resolution of ~100 years. Upstream lake filtering of river floodplains and lakes prevented finding a higher temporal resolution linkage between the sediment characteristics and headwater fluvial and glacial activity. Despite some upstream filtering, the Cariboo River was found to be the primary source of sediment to the long core sites. Observed grain size and varve thickness from two long cores show above average trends, which are coincident with cooler temperatures and the primary glacier advances over the last 2 ka.

Millennial‐Scale Changes in Atmospheric Nitrous Oxide During the Holocene

AbstractNitrous oxide (N2O) is an important greenhouse gas which destroys the ozone in the stratosphere. Primary sources of atmospheric N2O are nitrification and denitrification in terrestrial soils and the ocean, and the main sink is photolysis in the stratosphere. Studies have mostly focused on the climate‐related response of N2O during glacial‐interglacial periods. However, its mechanism of variation during the Holocene remains unclear. We present a high‐resolution N2O record from the South Pole Ice (SPICE) core covering the Holocene epoch. The millennial‐scale N2O trend agrees with existing records. We constructed a Holocene composite consisting of the new N2O measurements in SPICE and existing records from other ice core sites. The N2O composite reveals four distinct periods of N2O variation during 11.5–10.0 ka, 10.0–6.2 ka, 6.2–2.2 ka, and 2.2–1.4 ka, including two maxima in 11.0–10.0 ka and 3.0–2.2 ka and minima in 8.8–6.2 ka and approximately 1.4 ka. Apart from these, our new high‐resolution record from SPICE shows a short‐term N2O decrease around 2.8 ka which is not observed in other records possibly due to lower sample resolution and/or higher age smoothing. Comparison of our new Holocene N2O composite with the paleo‐proxy records suggests the plausible linkage of major monsoon (Asian, North African, South and North American, and Australian‐Indonesian monsoon) and upwelling (Arabian Sea and Eastern Tropical South Pacific) regions in regulating the atmospheric N2O during the Holocene.

Influence of flooding variability on the development of an Amazonian peatland

ABSTRACTPeat in the Pastaza–Marañón Foreland Basin (PMFB), northern Peru, forms beneath open wetlands, palm swamps, pole forests and seasonally flooded forests. These vegetation communities may represent different successional stages of peatlands, but the spatiotemporal patterns of peatland development in Amazonia are still poorly understood. We present a new geochemical and palaeoecological record spanning the last c. 4330 years from an open peatland (San Roque, core SAR_T3_03_B). Our results suggest the persistence of predominantly herbaceous vegetation communities at the core site since the start of peat accumulation (c. 3180 cal a bp). Micro‐X‐ray fluorescence core scanning provides evidence for episodes of fluvially derived minerogenic input and simultaneous increases in flood‐tolerant taxa relating to intervals of increased frequency and depth of riverine flooding. The establishment of Mauritia flexuosa palms from around 440 cal a bp coincided with a shift to lower flooding depth and frequency which continues to the present day. This study reveals the role of flooding variability in shaping peatland development and influencing vegetation succession in the PMFB, underlining the need to understand natural environmental variability for the conservation of these ecosystems due to their vital contributions to ecosystem services and carbon storage.

Mean Field Study of a Cylindrical Ferrimagnetic Nanotube with Different Anisotropies

In this paper, the ferrimagnetic mixed spins (1, 5/2) Blume-Capel model is proposed to investigate the phase diagrams and hysteresis behaviors of a magnetic cylindrical nanotube with a core-shell structure using the mean-field approximation based on the Bogoliubov inequality for the Gibbs free energy. The core sites are occupied by σ= ±1, 0 spins, whereas the shell sites are filled by S= ±5/2, ±3/2, ±1/2 spins. The effects of exchange couplings (Jin, JS) and single-ion anisotropies (DC, DS) on core, shell, and total magnetizations are investigated, as well as hysteresis behaviors. The entropy, free energy, and specific heat are analyzed to establish the stability of the solutions. The presentation and discussion of phase diagrams is detailed. The system shows a first-order and second-order phase transitions, as well as tricritical and critical end- points. In addition, the system shows compensation and reentrant behaviors. Various multiple hysteresis loop behaviors are seen according on the Hamiltonian parameters, such as the presence of triple, quintuple, and septuple hysteresis loops.

Conserving localized endemic butterflies through demographic and ecological studies: Polyommatus humedasae

1.Polyommatus humedasae is an endemic species narrowly distributed in a few sites in the Aosta Valley (NW Italy). Similarly to other alpine butterflies, the survival of the species is closely linked to the conservation of semi-natural grasslands.2.Despite the species being known since 1976, this is the first comprehensive data collection and analysis on this species, firstly to understand its distribution. At Pont d'Ael, the species core site, we applied the mark-release-recapture (MRR) method to estimate population size and density. To understand the species ecology, we collected data on preimaginal stages (eggs and larvae), host plants, and vegetation composition.3.The new data on species distribution (with 5 new sites and 2 subpopulations already extinct) permitted to update the extinction risk through IUCN assessment to Critically Endangered (CR). The estimated size (881 individuals) and density (73 N/ha) of the studied population are higher than those of other endemic Polyommatus species. Data suggest the species is monophagous on Onobrychis arenaria and prefers to lay eggs where the host plant is abundant, in ecotonal areas with some shrub cover (average 8 %), high herbaceous cover (average 68 %) and on plants in better physiological conditions.4.For species such as P. humedasae, which are threaten by woody encroachment, climate change, fires and collection, we propose the application of a management plan that includes: 1) mechanical cut of wood species; 2) small herds on a rotational basis to reduce woody encroachment and maintain shrub patches; 3) dissemination events to highlight the population importance.

Living on the edge: urban fireflies (Coleoptera, Lampyridae) in Morelia, Michoacán, Mexico.

Fireflies (Coleoptera, Lampyridae) are a globally threatened group of insects due to habitat loss and fragmentation, light pollution, climate change and pesticides. However, against all odds, some firefly populations persist in urbanized environments where all four of these factors are present simultaneously. In this work, we compiled several data sources to document the diversity of fireflies in the urbanized area of Morelia, characterize their current habitats, and determine the main stressors affecting these bioluminescent insects. We found seven genera and 26 species of fireflies (19 nocturnal, seven diurnal) associated with 32 urban, peri-urban and extra-urban areas; at least, 14 are new records for Michoacán, and the list for the state now includes nine genera and 41 species. Five additional sites were documented as extinction sites. We compared the characteristics of these five sites with those of the sites with extant populations. We found that in Morelia, fireflies are mainly associated with areas that have high to moderate proportions of vegetation cover, are near water bodies, have very gentle to moderate slopes, and are exposed to low levels of light pollution. In contrast, the extinction sites showed high proportions of artificial surfaces and high levels of light pollution. Because some fireflies are considered bioindicators of ecosystem integrity as they are associated to specific habitats, are highly diverse and due to their sensitivity to environmental changes, we consider that sites from Morelia's urban core and extinction sites show the highest levels of environmental degradation, threatening most fireflies and other insects living in the urban core with local extinction. At the same time, our results also suggest that implementing conservation strategies and sustainable planning for the urban development of Morelia in the short term could allow fireflies and other vital elements of the city's insect communities to persist for future generations. Restoration and conservation of green areas and nighttime environments are essential for biodiversity and human health, especially in intra-urban zones.

Identifying atmospheric processes favouring the formation of bubble-free layers in the Law Dome ice core, East Antarctica

Abstract. Physical features preserved in ice cores may provide unique records about past atmospheric variability. Linking the formation and preservation of these features and the atmospheric processes causing them is key to their interpretation as palaeoclimate proxies. We imaged ice cores from Law Dome, East Antarctica, using an intermediate layer core scanner (ILCS) and found that thin bubble-free layers (BFLs) occur multiple times per year at this site. The origin of these features is unknown. We used a previously developed age–depth scale in conjunction with regional accumulation estimated from atmospheric reanalysis data (ERA5) to estimate the year and month that the BFLs occurred, and then we performed seasonal and annual analysis to reduce the overall dating errors. We then investigated measurements of snow surface height from a co-located automatic weather station to determine snow surface features co-occurring with BFLs, as well as their estimated occurrence date. We also used ERA5 to investigate potentially relevant local/regional atmospheric processes (temperature inversions, wind scour, accumulation hiatuses and extreme precipitation) associated with BFL occurrence. Finally, we used a synoptic typing dataset of the southern Indian and southwest Pacific oceans to investigate the relationship between large-scale atmospheric patterns and BFL occurrence. Our results show that BFLs occur (1) primarily in autumn and winter, (2) in conjunction with accumulation hiatuses > 4 d, and (3) during synoptic patterns characterised by meridional atmospheric flow related to the episodic blocking and channelling of maritime moisture to the ice core site. Thus, BFLs may act as a seasonal marker (autumn/winter) and may indicate episodic changes in accumulation (such as hiatuses) associated with large-scale circulation. This study provides a pathway to the development of a new proxy for past climate in the Law Dome ice cores, specifically past snowfall conditions relating to synoptic variability over the southern Indian Ocean.

Large shift in the upper water column characteristics of the west-central Bay of Bengal during the last glacial-interglacial transition

The upper water column structure in the Bay of Bengal is strongly influenced by the monsoon and associated processes. However, the records of variation in water column stratification during different monsoon phases, are scarce from this region. Here, we have reconstructed the variation in monsoon induced upwelling, mixed layer and thermocline during the last glacial-interglacial transition, by using the relative abundance of mixed layer and thermocline dwelling planktic foraminifera, relative abundance of Globigerina bulloides and the stable oxygen isotopic ratio (δ18O) of surface dwelling Globigerinoides ruber. We report a weaker upwelling during the last glacial interval and late Greenlandian-Northgrippian Age, and strong upwelling during the deglaciation and Meghalayan Age. The intense upwelling shoaled the thermocline during the early glacial interval, last glacial maximum, late deglaciation and the Meghalayan Age. The mixed layer depth increased during the early deglaciation and Late Greenlandian-Northgrippian due to the reduced upwelling and stronger winter monsoon. The shift in the position of the core site with respect to the low salinity coastal currents, due to the rising sea level, also influenced the upper water column structure in the west-central Bay of Bengal. Therefore, the reorganization of the upper water column structure in the west-central Bay of Bengal, on the glacial-interglacial time scale, was mainly influenced by a combination of the upwelling, fresh water influx, sea level and winter monsoon.

Confronting algorithmic management using subject access requests: Insights using the case of food deliveries

AbstractGig work is defined by a (mostly) automated management, operating remotely through an app. Without human interaction, workers are left with only guesses about the functioning of the algorithms they are subjected to. To better position themselves in their competition for tasks, they try to influence the data profile that platform build about them. Made of performance indicators, personal information, and sensor data, these profiles are an essential part of algorithmic management. This paper will identify data profiles as core sites of the struggle in the gig economy. It will discuss the benefits and limitations of bringing data at the centre stage through a workers’ inquiry of food delivery platforms. The analysis will distinguish three actors in this inquiry and discuss their uses of data profiles: the couriers themselves, as they attempt to make sense of algorithmic management; the researcher, and how they can use personal data in order to reconstitute this field of struggle; and the trade unions, which can provide a way to collectivise data governance and gain better information in building their case in favour of gig workers’ rights.

Investigating the spatial representativeness of East Antarctic ice cores: a comparison of ice core and radar-derived surface mass balance over coastal ice rises and Dome Fuji

Abstract. Surface mass balance (SMB) of the Antarctic Ice Sheet must be better understood to document the current Antarctic contribution to sea-level rise. In situ point data using snow stakes and ice cores are often used to evaluate the state of the ice sheet's mass balance, as well as to assess SMB derived from regional climate models, which are then used to produce future climate projections. However, spatial representativeness of individual point data remains largely unknown, particularly in the coastal regions of Antarctica with highly variable terrain. Here, we compare ice core data collected at the summit of eight ice rises along the coast of Dronning Maud Land, as well as at the Dome Fuji site, and shallow ice-penetrating radar data over these regions. Shallow radar data have the advantage of being spatially extensive, with a temporal resolution that varies between a yearly and multi-year resolution, from which we can derive a SMB record over the entire radar survey. This comparison therefore allows us to evaluate the spatial variability of SMB and the spatial representativeness of ice-core-derived SMB. We found that ice core mean SMB is very local, and the difference with radar-derived SMB increases in a logarithmic fashion as the surface covered by the radar data increases, with a plateau ∼ 1–2 km away from the ice crest for most ice rises, where there are strong wind–topography interactions, and ∼ 10 km where the ice shelves begin. The relative uncertainty in measuring SMB also increases rapidly as we move away from the ice core sites. Five of our ice rise sites show a strong spatial representativeness in terms of temporal variability, while the other three sites show that it is limited to a surface area between 20–120 km2. The Dome Fuji site, on the other hand, shows a small difference between pointwise and area mean SMB, as well as a strong spatial representativeness in terms of temporal variability. We found no simple parameterization that could represent the spatial variability observed at all the sites. However, these data clearly indicate that local spatial SMB variability must be considered when assessing mass balance, as well as comparing modeled SMB values to point field data, and therefore must be included in the estimate of the uncertainty of the observations.

The late Quaternary palynological record of the northern Yangtze Delta: Implication for palaeoclimate change in East Asia

Marine Isotope Stage (MIS) 3 is the latest interstadial period with unstable climate regimes that provides an indispensable key to better predict future climate change. However, paleoclimate reconstruction in the Yangtze Delta covering MIS 3 remains elusive due to limited archives with reliable age. Here, we derived a 53,000–year–long paleoclimate record from the northern Yangtze Delta, using luminescence age–based palynological data of a coastal sediment core (YZ07). The results show that the climate was relatively warm and wet during ∼53.0–37.5 ka, followed by a slightly cool but wetter condition between ∼37.5 ka and ∼33.2 ka. Afterwards, a cool and dry climate prevailed from ∼33.2 ka to ∼30.7 ka. Three cold events were identified around 48.0 ka, 39.0 ka and 31.0 ka, corresponding to the timings of Heinrich Event (HE 5), HE 4 and HE 3, respectively. From ∼30.7 ka to ∼11.5 ka, broadleaved forests and wetland herbs obviously contracted in the Yangtze Delta region, indicating cold and dry climate conditions. From the late Pleistocene to Holocene, the pollen variations in this core site were linked to coastal geomorphology under climate–induced sea–level changes. Besides, our findings suggest that the percentages of emergent vegetation in this work were negatively correlated with El Niño–Southern Oscillation (ENSO)–linked flood events during the Holocene. Overall, from mid–MIS 3 to MIS 2, the climate exhibits a ‘warm–cool–cold’ pattern in the Yangtze Delta, broadly concordant with other climate proxies in East Asian monsoon domain and beyond on suborbital or millennial timescales. We argue that the northern hemisphere summer insolation may be responsible for the paleoclimate variability and paleovegetation successions in the Yangtze Delta. However, the variability of precipitation in MIS 3 might be governed by interhemispheric insolation forcing, which accounts for a wetter climate phase occurring during late MIS 3 rather than mid–MIS 3.

Glacial expansion of carbon-rich deep waters into the Southwestern Indian Ocean over the last 630 kyr

Oceanic carbon storage is one of the main sinks for atmospheric CO2, and thought to be the major contributing factor for CO2 drawdown during past glacial periods. Both physical and biogeochemical processes control the capacity of carbon storage in the ocean. During glacial periods of the Pleistocene the larger volume of deep-water masses of Southern Hemisphere origin in the Atlantic has been shown to promote carbon storage in the Southern Ocean. However, the latitudinal extension of this water mass in the Indian Ocean has been scarcely studied. In this study, we combine foraminiferal εNd and benthic δ13C of two sediment cores in the southwest Indian Ocean (MD96–2077, 33°S, 3781 m water depth; MD96–2052, 19°S, 2627 m water depth), to reconstruct the spatial and temporal evolution of glacial carbon-rich deep waters in the SW Indian over the last 630 kyr. The combined use of foraminiferal εNd and benthic δ13C allows to distinguish δ13C changes related to water mass mixing and from respired carbon accumulation within the water masses. Nutrient-rich deep waters, which cannot be explained by the enhanced proportion of southern-sourced waters, were present at core sites deeper than 2700 m during glacial periods and extended at least until 33°S into the SW Indian Ocean. From Marine Isotope Stage (MIS) 14 to MIS 10, glacial carbon storage increased gradually until reaching its highest capacity during the extreme glacial periods MIS 12 and 10. Orbital forcing (100-kyr eccentricity, 41-kyr obliquity), restricted air-sea exchange and enhanced ocean stratification, fostered higher carbon storage during periods of relatively lower eccentricity and obliquity. Furthermore, after MIS 10, a progressive transition was observed from 100-kyr eccentricity to 41-kyr obliquity cycles in benthic δ13C and δ18O records of core MD96–2077 and sea-ice cover changes derived from ice-rafted debris of the Agulhas Plateau composite core site.

A Novel Shipyard Production State Monitoring Method Based on Satellite Remote Sensing Images

Monitoring the shipyard production state is of great significance to shipbuilding industry development and coastal resource utilization. In this article, it is the first time that satellite remote sensing (RS) data is utilized to monitor the shipyard production state dynamically and efficiently, which can make up for the traditional production state data collection mode. According to the imaging characteristics of optical remote sensing images in shipyards with a different production state, the characteristics are analyzed to establish reliable production state evidence. Firstly, in order to obtain the characteristics of the production state of optical remote sensing data, the high-level semantic information in the shipyard is extracted by transfer learning convolutional neural networks (CNNs). Secondly, in the evidence fusion, for the conflict evidence from the core sites of the shipyard, an improved DS evidence fusion method is proposed, which constructs the correlation metric to measure the degree of conflict in evidence and designs the similarity metric to measure the credibility of evidence. Thirdly, the weight of all the evidence is calculated according to the similarity metric to correct the conflict evidence. The introduction of the iterative idea is motivated by the fact that the fusion result aligns more closely with the desired result, the iterative idea is introduced to correct the fusion result. This method can effectively solve the conflict of evidence and effectively improve the monitoring accuracy of the shipyard production state. In the experiments, the Yangtze River Delta and the Bohai Rim are selected to verify that the proposed method can accurately recognize the shipyard production state, which reveals the potential of satellite RS images in shipyard production state monitoring, and also provides a new research thought perspective for other industrial production state monitoring.

Working conditions at the workplaces of core sections of foundries

The working conditions at the workplaces of foundry workers when performing work on core sites, production factors determining them are considered. The results of studies of the parameters of the working conditions of the considered professions of foundry workers in comparison with the standard values are presented. It is established that in a comprehensive assessment of the working conditions of workers in the core sections of foundries, it is necessary to take into account the duration of stay at the working equipment, the equipment and hand tools used, the type of alloy being smelted (steel, cast iron, non‑ferrous metals) and the nature of the production.

Plasma phosphorylated tau181 as a biomarker of mild traumatic brain injury: findings from THINC and NCAA-DoD CARE Consortium prospective cohorts.

The aim of this study was to investigate phosphorylated tau (p-tau181) protein in plasma in a cohort of mild traumatic brain injury (mTBI) patients and a cohort of concussed athletes. This pilot study comprised two independent cohorts. The first cohort-part of a Traumatic Head Injury Neuroimaging Classification (THINC) study-with a mean age of 46 years was composed of uninjured controls (UIC, n = 30) and mTBI patients (n = 288) recruited from the emergency department with clinical computed tomography (CT) and research magnetic resonance imaging (MRI) findings. The second cohort-with a mean age of 19 years-comprised 133 collegiate athletes with (n = 112) and without (n = 21) concussions. The participants enrolled in the second cohort were a part of a multicenter, prospective, case-control study conducted by the NCAA-DoD Concussion Assessment, Research and Education (CARE) Consortium at six CARE Advanced Research Core (ARC) sites between 2015 and 2019. Blood was collected within 48 h of injury for both cohorts. Plasma concentration (pg/ml) of p-tau181 was measured using the Single Molecule Array ultrasensitive assay. Concentrations of plasma p-tau181 in both cohorts were significantly elevated compared to controls within 48 h of injury, with the highest concentrations of p-tau181 within 18 h of injury, with an area under the curve (AUC) of 0.690-0.748, respectively, in distinguishing mTBI patients and concussed athletes from controls. Among the mTBI patients, the levels of plasma p-tau181 were significantly higher in patients with positive neuroimaging (either CT+/MRI+, n = 74 or CT-/MRI+, n = 89) compared to mTBI patients with negative neuroimaging (CT-/MRI-, n = 111) findings and UIC (P-values < 0.05). These findings indicate that plasma p-tau181 concentrations likely relate to brain injury, with the highest levels in patients with neuroimaging evidence of injury. Future research is needed to replicate and validate this protein assay's performance as a possible early diagnostic biomarker for mTBI/concussions.

Climatology of the Mount Brown South ice core site in East Antarctica: implications for the interpretation of a water isotope record

Abstract. Water stable isotope records from ice cores (δ18O and δD) are a critical tool for constraining long-term temperature variability at high latitudes. However, precipitation in Antarctica consists of semi-continuous small events and intermittent extreme events. In regions of high accumulation, this can bias ice core records towards recording the synoptic climate conditions present during extreme precipitation events. In this study we utilise a combination of ice core data, reanalysis products, and models to understand how precipitation intermittency impacts the temperature records preserved in an ice core from Mount Brown South in East Antarctica. Extreme precipitation events represent only the largest 10 % of all precipitation events, but they account for 52 % of the total annual snowfall at this site, leading to an overrepresentation of these events in the ice core record. Extreme precipitation events are associated with high-pressure systems in the mid-latitudes that cause increased transport of warm and moist air from the southern Indian Ocean to the ice core site. Warm temperatures associated with these events result in a +4.8 ∘C warm bias in the mean annual temperature when weighted by daily precipitation, and water isotopes in the Mount Brown South ice core are shown to be significantly correlated with local temperature when this precipitation-induced temperature bias is included. The Mount Brown South water isotope record spans more than 1000 years and will provide a valuable regional reconstruction of long-term temperature and hydroclimate variability in the data-sparse southern Indian Ocean region.