The Sediment Green-Blue Color Ratio as a Proxy for Biogenic Silica Productivity Along the Chilean Margin

Sediment cores recently collected from the Chilean Margin during D/V JOIDES Resolution Expedition 379T (JR100) document variability in shipboard-generated records of the green/blue (G/B) ratio. These changes show a strong coherence with benthic foraminiferal δ18O, Antarctic ice core records, and sediment lithology (e.g., higher diatom abundances in greener sediment intervals), suggesting a climate-related control on the G/B. Here, we test the utility of G/B as a proxy for diatom productivity at Sites J1002 and J1007 by calibrating G/B to measured biogenic opal. Strong exponential correlations between measured opal% and the G/B were found at both sites. We use the empirical regressions to generate high-resolution records of opal contents (opal%) on the Chilean Margin. Higher productivity tends to result in more reducing sedimentary conditions. Redox-sensitive sedimentary U/Th generally co-varies with the reconstructed opal% at both sites, supporting the association between sediment color, sedimentary U/Th, and productivity. Lastly, we calculated opal mass accumulation rate (MAR) at Site J1007 over the last ∼150,000 years. The G/B-derived opal MAR record from Site J1007 largely tracks existing records derived from traditional wet-alkaline digestion from the south and eastern equatorial Pacific (EEP) Ocean, with a common opal flux peak at ∼50 ka suggesting that increased diatom productivity in the EEP was likely driven by enhanced nutrient supply from the Southern Ocean rather than dust inputs as previously suggested. Collectively, our results identify the G/B ratio as a useful tool with the potential to generate reliable, high-resolution paleoceanographic records that circumvent the traditionally laborious methodology.publishedVersio

Deep submarine infiltration of altered geothermal groundwater on the south Chilean Margin

Submarine groundwater discharge is increasingly recognized as an important component of the oceanic geochemical budget, but knowledge of the distribution of this phenomenon is limited. To date, reports of meteoric inputs to marine sediments are typically limited to shallow shelf and coastal environments, whereas contributions of freshwater along deeper sections of tectonically active margins have generally been attributed to silicate diagenesis, mineral dehydration, or methane hydrate dissociation. Here, using geochemical fingerprinting of pore water data from Site J1003 recovered from the Chilean Margin during D/V JOIDES Resolution Expedition 379 T, we show that substantial offshore freshening reflects deep and focused contributions of meteorically modified geothermal groundwater, which is likely sourced from a reservoir ~2.8 km deep in the Aysén region of Patagonia and infiltrated marine sediments during or shortly after the last glacial period. Emplacement of fossil groundwaters reflects an apparently ubiquitous phenomenon in margin sediments globally, but our results now identify an unappreciated locus of deep submarine groundwater discharge along active margins with potential implications for coastal biogeochemical processes and tectonic instability.publishedVersio

A Near-Peer Educational Model for Online, Interactive Learning in Emergency Medicine

Introduction: The COVID-19 pandemic led to a large disruption in the clinical education of medical students, particularly in-person clinical activities. To address the resulting challenges faced by students interested in emergency medicine (EM), we proposed and held a peer-led, online learning course for rising fourth-year medical students.Methods: A total of 61 medical students participated in an eight-lecture EM course. Students were evaluated through pre- and post-course assessments designed to ascertain perceived comfort with learning objectives and overall course feedback. Pre- and post-lecture assignments were also used to increase student learning.Results: Mean confidence improved in every learning objective after the course. Favored participation methods were three-person call-outs, polling, and using the “chat” function. Resident participation was valued for “real-life” examples and clinical pearls.Conclusion: This interactive model for online EM education can be an effective format for dissemination when in-person education may not be available.

A Near-Peer Educational Model for Online, Interactive Learning in Emergency Medicine

Introduction: The COVID-19 pandemic led to a large disruption in the clinical education of medical students, particularly in-person clinical activities. To address the resulting challenges faced by students interested in emergency medicine (EM), we proposed and held a peer-led, online learning course for rising fourth-year medical students.Methods: A total of 61 medical students participated in an eight-lecture EM course. Students were evaluated through pre- and post-course assessments designed to ascertain perceived comfort with learning objectives and overall course feedback. Pre- and post-lecture assignments were also used to increase student learning.Results: Mean confidence improved in every learning objective after the course. Favored participation methods were three-person call-outs, polling, and using the “chat” function. Resident participation was valued for “real-life” examples and clinical pearls.Conclusion: This interactive model for online EM education can be an effective format for dissemination when in-person education may not be available.

Microvascular Reconstruction of Osteonecrosis: Assessment of Long-term Quality of Life

Objective Review long-term clinical and quality-of-life outcomes following free flap reconstruction for osteonecrosis. Study Design Retrospective multi-institutional review. Setting Tertiary care centers. Methods Patients included those undergoing free flap reconstructions for osteonecrosis of the head and neck (N = 232). Data included demographics, defect, donor site, radiation history, perioperative management, diet status, recurrence rates, and long-term quality-of-life outcomes. Quality-of-life outcomes were measured using the University of Washington Quality of Life (UW-QOL) survey. Results Overall flap success rate was 91% (n = 212). Relative to preoperative diet, 15% reported improved diet function at 3 months following reconstruction and 26% at 5 years. Osteonecrosis recurred in 14% of patients (32/232); median time to onset was 11 months. Cancer recurrence occurred in 13% of patients (29/232); median time to onset was 34 months. Results from the UW-QOL questionnaire were as follows: no pain (45%), minor or no change in appearance (69%), return to baseline endurance level (37%), no limitations in recreation (40%), no changes in swallowing following reconstruction (28%), minor or no limitations in mastication (29%), minor or no speech difficulties (93%), no changes in shoulder function (84%), normal taste function (19%), normal saliva production (27%), generally excellent mood (44%), and no or minimal anxiety about cancer (94%). Conclusion The majority of patients maintained or had advancement in diet following reconstruction, with low rates of osteonecrosis or cancer recurrence and above-average scores on UW-QOL survey suggesting good return of function and quality of life

Imaging glial activation in patients with post-treatment Lyme disease symptoms: a pilot study using [11C]DPA-713 PET

Abstract The pathophysiology of post-treatment Lyme disease syndrome (PTLDS) may be linked to overactive immunity including aberrant activity of the brain’s resident immune cells, microglia. Here we used [11C]DPA-713 and positron emission tomography to quantify the 18 kDa translocator protein, a marker of activated microglia or reactive astrocytes, in the brains of patients with post-treatment Lyme disease symptoms of any duration compared to healthy controls. Genotyping for the TSPO rs6971 polymorphism was completed, and individuals with the rare, low affinity binding genotype were excluded. Data from eight brain regions demonstrated higher [11C]DPA-713 binding in 12 patients relative to 19 controls. [11C]DPA-713 PET is a promising tool to study cerebral glial activation in PTLDS and its link to cognitive symptoms