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Supply of iron (Fe) to the surface ocean supports primary productivity, and while hydrothermal input of Fe to the deep ocean is known to be extensive it remains poorly constrained. Global estimates of hydrothermal Fe supply rely on using dissolved Fe (dFe) to excess He (xs3He) ratios to upscale fluxes, but observational constraints on dFe/xs3He may be sensitive to assumptions linked to sampling and interpolation. We examined the variability in dFe/xs3He using two methods of estimation, for four vent sites with different geochemistry along the Mid-Atlantic Ridge. At both Rainbow and TAG, the plume was sampled repeatedly and the range of dFe/xs3He was 4 to 63 and 4 to 87 nmol:fmol, respectively, primarily due to differences in plume age. To account for background xs3He and shifting plume position, we calibrated He values using contemporaneous dissolved Mn (dMn). Applying this approach more widely, we found dFe/xs3He ratios of 12, 4–8, 4–44, and 4–86 nmol fmol−1 for the Menez Gwen, Lucky Strike, Rainbow, and TAG hydrothermal vent sites, respectively. Differences in plume dFe/xs3He across sites were not simply related to the vent endmember Fe and He fluxes. Within 40 km of the vents, the dFe/xs3He ratios decreased to 3–38 nmol fmol−1, due to the precipitation and subsequent settling of particulates. The ratio of colloidal Fe to dFe was consistently higher (0.67–0.97) than the deep N. Atlantic (0.5) throughout both the TAG and Rainbow plumes, indicative of Fe exchange between dissolved and particulate phases. Our comparison of TAG and Rainbow shows there is a limit to the amount of hydrothermal Fe released from vents that can form colloids in the rising plume. Higher particle loading will enhance the longevity of the Rainbow hydrothermal plume within the deep ocean assuming particles undergo continual dissolution/disaggregation. Future studies examining the length of plume pathways required to escape the ridge valley will be important in determining Fe supply from slow spreading mid-ocean ridges to the deep ocean, along with the frequency of ultramafic sites such as Rainbow. Resolving the ridge valley bathymetry and accounting for variability in vent sources in global biogeochemical models will be key to further constraining the hydrothermal Fe flux.

Objective: Our primary aim was to identify a low-risk subgroup of older adults (aged 65 and older) presenting to ED with minor head trauma which can be safely managed without a cranial CT (cCT)., Methods: This was a single-site, prospective, observational, cohort study conducted at a major-referral ED. Alert, haemodynamically stable, older adults with suspected head trauma were eligible. This included both community dwellers and residential aged care facility (RACF) residents. Primary outcome was the proportion of patients who had a clinically important traumatic brain injury (ciTBI) within 42 days of index ED presentation. Secondary outcomes included proportion investigated with a cCT, and proportion needing neurosurgical intervention., Results: Two hundred seventy-six patients (mean age 80.5 years; 53.6% female) were enrolled. The most common mechanism of injury was ground-level fall (93.8%). One in four patients was from RACFs, 30.1% had dementia and 52.2% were on blood thinners. 80.8% had a cCT during the index ED visit. Seven (2.5%) patients had ciTBI within 42 days of index ED presentation. Patients with ciTBI had either external signs of head injury or abnormal neurological exam. All patients with ciTBI were treated conservatively after shared decision-making., Conclusions: Alert, haemodynamically stable, older ED adults with suspected head trauma had a low incidence of ciTBI in the present study. Abnormal physical examination findings were consistently present in patients with ciTBI. Shared decision-making prior to cCT may be the pragmatic way ahead in the management of this patient cohort, especially among those from RACFs., (© 2024 Australasian College for Emergency Medicine.)

Phytoplankton growth in large parts of the world ocean is limited by low availability of dissolved iron (dFe), restricting oceanic uptake of atmospheric CO 2 . The bioavailability of dFe in seawater is however difficult to appraise since it is bound by a variety of poorly characterized organic ligands. Here, we propose a new approach for evaluating seawater dFe bioavailability based on its uptake rate constant by Fe-limited cultured phytoplankton. We utilized seven phytoplankton species of diverse classes, sizes, and provenances to probe for dFe bioavailability in 12 seawater samples from several ocean basins and depths. All tested phytoplankton acquired organically bound Fe in any given sample at similar rates (after normalizing to cellular surface area), confirming that multiple, Fe-limited phytoplankton species can be used to probe dFe bioavailability in seawater. These phytoplankton-based uptake rate constants allowed us to compare water types, and obtain a grand average estimate of seawater dFe bioavailability. Among water types, dFe bioavailability varied by approximately four-fold, and did not clearly correlate with Fe concentrations or any of the measured Fe speciation parameters. Compared with well-studied Fe complexes, seawater dFe is more available than model siderophore Fe, but less available than inorganic Fe. Exposure of seawater to sunlight, however, significantly enhanced dFe bioavailability. The rate constants established in this work, not only facilitate comparison between water types, but also allow calculation of Fe uptake rates by phytoplankton in the ocean based on measured dFe concentrations. The approach established and verified in this study, opens a new way for determining dFe bioavailability in samples across the ocean, and enables modeling of in situ Fe uptake rates by phytoplankton using dFe concentrations from GEOTRACES datasets.

Introduction: The literature suggests that there is variation in various features of the written radiology report for a range of body areas and imaging modalities. The retrospective study presented here aims to determine if similar variation is demonstrated in a group of 5 reporting radiographers in a UK NHS Trust., Methods: Full reports for 1530 knee radiographic examinations performed from accident and emergency referrals were extracted for a 12-month period from a Radiology Information System (RIS) into Excel. Copied into Word, the word count function was used for each report and the number of words and characters (without spaces) was returned into Excel. Average word count and word length per report, by radiographer, were calculated for the following sections of the report: report title, main body and signature. SPSS was used to perform inferential statistical analysis., Results: A wide range in the maximum and minimum average report lengths (60.88 v 17.83 words) was demonstrated. Statistically significant differences (p < 0.05) were seen between all but one pair-wise comparison (Rad 2 v Rad 4; p = 0.98) for the overall report length; for the length of the findings section, four pair-wise comparisons did not reach significance. Average word length demonstrated less variation. 4 out of 5 radiographers always included a report title; 3 out of 5 never included a report signature. There was a strong negative correlation between experience and report length., Conclusion: Variation in report structure and length, as well as word length, was seen, comparable to studies of radiologist reports. Further research is required to investigate the drivers of this variation, and determine if there is any clinical significance., (Copyright © 2018 The College of Radiographers. Published by Elsevier Ltd. All rights reserved.)

Grasslands throughout the world are responding in diverse ways to changing climate and environmental conditions. In this study we analyze indicators of phosphorus limitation including phosphorus concentrations, phosphorus to nitrogen, and carbon ratios, oxygen isotope ratios of phosphate in vegetation, and phosphatase enzyme activity in soil to shed light on potential effects of climate change on phosphorus availability to grassland vegetation. The study was conducted at the Jasper Ridge Global Change Experiment (JRGCE), California where manipulations mimicking increases in temperature, water, nitrogen and carbon-dioxide have been maintained for over 15 years. We compare our results to an earlier study conducted 3 years after the start of the experiment, in order to assess any change in the response of phosphorus over time. Our results suggest that a decade later the measured indicators show similar or only slightly stronger responses. Specifically, addition of nitrogen, the principle parameter controlling biomass growth, increased phosphorus demand but thresholds that suggest P limitation were not reached. A study documenting changes in net primary productivity (NPP) over time at the JRGCE also could not identify a progressive effect of the manipulations on NPP. Combined these results indicate that the vegetation in these grassland systems is not very sensitive to the range of climate parameters tested.

Objective: To describe current practice of EDUS by ACEM Trainees and Fellows; to describe potential barriers to US use in the Australasian setting; to determine compliance with current college guidelines regarding US credentialing., Methods: Data were collected by a cross-sectional online survey. Respondents were Trainees and Fellows of the ACEM. Outcome measures included the percentage of respondents currently undergoing or that had completed US credentialing for Focused Assessment with Sonography for Trauma (FAST) and assessment of abdominal aortic aneurysm (AAA) scans. The perceived barriers to use of emergency US were explored., Results: There were 512 survey respondents, giving an overall response rate of 15%. Fellows were more likely to be credentialed compared with Trainees. There were 61% of respondents not credentialed for FAST and assessment of AAA scans. However, a significant proportion performed these scans regularly, and did not routinely seek independent confirmation of their findings. Barriers to credentialing included limited time and no credentialing programme at the individual's hospital., Conclusions: The present study showed that only a minority of ACEM Trainees and Fellows are credentialed to perform routine ED scans. Many non-credentialed ACEM Trainees and Fellows are performing scans, many without independent confirmation of their findings., (© 2014 Australasian College for Emergency Medicine and Australasian Society for Emergency Medicine.)