Neutrinos interact only very weakly, so they are extremely penetrating. The theoretical neutrino-nucleon interaction cross-section, however, increases with increasing neutrino energy, and neutrinos with energies above 40 teraelectronvolts (TeV) are expected to be absorbed as they pass through the Earth. Experimentally, the cross-section has been determined only at the relatively low energies (below 0.4 TeV) that are available at neutrino beams from accelerators. Here we report a measurement of neutrino absorption by the Earth using a sample of 10,784 energetic upward-going neutrino-induced muons. The flux of high-energy neutrinos transiting long paths through the Earth is attenuated compared to a reference sample that follows shorter trajectories. Using a fit to the two-dimensional distribution of muon energy and zenith angle, we determine the neutrino-nucleon interaction cross-section for neutrino energies 6.3-980 TeV, more than an order of magnitude higher than previous measurements. The measured cross-section is about 1.3 times the prediction of the standard model, consistent with the expectations for charged- and neutral-current interactions. We do not observe a large increase in the cross-section with neutrino energy, in contrast with the predictions of some theoretical models, including those invoking more compact spatial dimensions or the production of leptoquarks. This cross-section measurement can be used to set limits on the existence of some hypothesized beyond-standard-model particles, including leptoquarks.

Older adults often show declines in memory performance relative to younger adults. One potential path for helping older adults with memory is compensatory memory training programs. Ecologically Oriented Neurorehabilitation of Memory (EON-Mem) is a method for teaching memory strategies that may generalize for use in everyday contexts. We performed a feasibility study to determine the value of pursuing a group-based version of EON-Mem with older adults in a future randomized controlled trial. The current feasibility study took place with two separate samples: healthy young adults (n=39) and older adults (n=26). We collected data on recruitment, treatment adherence, memory improvement, drop-out rate, cost, time spent, and participant-report data on barriers to successful implementation of EON-Mem treatment. Participants first performed a baseline assessment (e.g., memory, cognition, and emotional functioning), followed by weekly treatment sessions for seven weeks. We prematurely ended older adult group treatment sessions due to the COVID-19 pandemic. All participants performed a post-intervention assessment using alternate versions when available. Attendance rates were low for the young adult sample (51% completed the treatment) and as expected for the older adult sample when accounting for COVID-related changes (77% eligible for completer status prior to cancelling sessions). Only 20% of each sample reliably improved on the RBANS delayed memory index. Costs were higher than expected. Costs were $345 and 18.6 research hours for each young adult participant, $319 and 16.9 research hours for each older adult participant. Although a randomized controlled trial of group-format EON-Mem in older adults is feasible, such a study may not be cost-effective.

In studies of event-related brain potentials (ERPs), difference scores between conditions in a task are frequently used to isolate neural activity for use as a dependent or independent variable. Adequate score reliability is a prerequisite for studies examining relationships between ERPs and external correlates, but there is a widely held view that difference scores are inherently unreliable and unsuitable for studies of individual differences. This view fails to consider the nuances of difference score reliability that are relevant to ERP research. In the present study, we provide formulas from classical test theory and generalizability theory for estimating the internal consistency of subtraction-based and residualized difference scores. These formulas are then applied to error-related negativity (ERN) and reward positivity (RewP) difference scores from the same sample of 117 participants. Analyses demonstrate that ERN difference scores can be reliable, which supports their use in studies of individual differences. However, RewP difference scores yielded poor reliability due to the high correlation between the constituent reward and non-reward ERPs. Findings emphasize that difference score reliability largely depends on the internal consistency of constituent scores and the correlation between those scores. Furthermore, generalizability theory estimates yielded higher internal consistency estimates for subtraction-based difference scores than classical test theory estimates did. Despite some beliefs that difference scores are inherently unreliable, ERP difference scores can show adequate reliability and be useful for isolating neural activity in studies of individual differences.