Radiative Forcing by Dust and Black Carbon on the Juneau Icefield, Alaska

Here we present the first known data set on black carbon (BC) and mineral dust concentrations in snow from the Juneau Icefield (JIF) in southeastern Alaska, where glacier melt rates are among the highest on Earth. In May 2016, concentrations of BC (0.4–3.1 μg/L) and dust (0.2–34 mg/L) were relatively low and decreased toward the interior of the JIF. The associated radiative forcing (RF) averaged 4 W/m2. In July, after 10 weeks of exposure, the aged snow surface had substantially higher concentrations of BC (2.1–14.8 μg/L) and dust (11–72 mg/L) that were not spatially distributed by elevation or distance from the coast. RF by dust and BC ranged from 70 to 130 W/m2 (87 W/m2 average) across the JIF in July, and RF was dominated by dust. The associated median snow water equivalent reduction in the July samples is estimated at 10–18 mm/day, potentially advancing melt on the scale of days to weeks. Aging of the snow surface in summer likely resulted in a positive feedback of melt consolidation, enhanced solar absorption and melting, and further concentration of surface particles. Regional projections of warming temperatures and increased rain at the expense of snow make it likely that summer season darkening will become a more important contributor to the high melt rates on the JIF. Further studies are needed to elucidate the spatiotemporal occurrence of various light‐absorbing particles on the JIF, and models of ice field wastage should incorporate their associated RF

Characterisation of strip silicon detectors for the ATLAS Phase-II Upgrade with a micro-focused X-ray beam

The planned HL-LHC (High Luminosity LHC) in 2025 is being designed to maximise the physics potential through a sizable increase in the luminosity up to 6 · 1034 cm−2 s −1 . A consequence of this increased luminosity is the expected radiation damage at 3000 fb−1 after ten years of operation, requiring the tracking detectors to withstand fluences to over 1 · 1016 1 MeV neq/cm2 . In order to cope with the consequent increased readout rates, a complete re-design of the current ATLAS Inner Detector (ID) is being developed as the Inner Tracker (ITk). Two proposed detectors for the ATLAS strip tracker region of the ITk were characterized at the Diamond Light Source with a 3 µm FWHM 15 keV micro focused X-ray beam. The devices under test were a 320 µm thick silicon stereo (Barrel) ATLAS12 strip mini sensor wire bonded to a 130 nm CMOS binary readout chip (ABC130) and a 320 µm thick full size radial (end-cap) strip sensor - utilizing bi-metal readout layers - wire bonded to 250 nm CMOS binary readout chips (ABCN-25). A resolution better than the inter strip pitch of the 74.5 µm strips was achieved for both detectors. The effect of the p-stop diffusion layers between strips was investigated in detail for the wire bond pad regions. Inter strip charge collection measurements indicate that the effective width of the strip on the silicon sensors is determined by p-stop regions between the strips rather than the strip pitch

Crowdsourced estimation of cognitive decline and resilience in Alzheimer's disease

Identifying accurate biomarkers of cognitive decline is essential for advancing early diagnosis and prevention therapies in Alzheimer's disease. The Alzheimer's disease DREAM Challenge was designed as a computational crowdsourced project to benchmark the current state-of-the-art in predicting cognitive outcomes in Alzheimer's disease based on high dimensional, publicly available genetic and structural imaging data. This meta-analysis failed to identify a meaningful predictor developed from either data modality, suggesting that alternate approaches should be considered for prediction of cognitive performance

Hydrology: Chemistry of fresh water; 1860 Hydrology: Runoff and streamflow; 1871 Hydrology: Surface water quality; 1803 Hydrology: Anthropogenic effects; 1065 Geochemistry: Trace elements (3670)

[1] Seasonal variations in stream inorganic geochemistry are not well documented or understood. We sampled two mining-impacted and two relatively pristine streams in western Montana over a 12-month period, collecting samples every 4 weeks, with supplemental sampling (at least weekly) during spring runoff. We analyzed all samples for dissolved (operationally defined as <0.2 mm) and total recoverable concentrations. Generally, the trace elements (Al, As, Cu, Fe, Mn, and Zn) did not correlate linearly with streamflow, while the major elements (e.g., Ca, K, and Mg) did. Suspended sediment, total recoverable metals, and H + followed clockwise hysteresis rotations, driven by short-term flushing events during the very early stages of spring runoff. Mining-impacted sites had higher concentrations of many trace elements than did relatively pristine sites. One of the mining impacted sites exhibited strong geochemical responses to spring rain events in the basin. The results underscore the need to sample streams frequently during changing hydrologic and climatic conditions in order to accurately monitor surface water quality and to determine solute and particulate loads (both contaminant and noncontaminant)