The data volumes generated by theWidefield ASKAP L-band Legacy All-sky Blind surveY atomic hydrogen (Hi) survey using the Australian Square Kilometre Array Pathfinder (ASKAP) necessitate greater automation and reliable automation in the task of source finding and cataloguing. To this end, we introduce and explore a novel deep learning framework for detecting low signal-to-noise ratio (SNR) Hi sources in an automated fashion. Specifically, our proposed method provides an automated process for separating true Hi detections from false positives when used in combination with the source finding application output candidate catalogues. Leveraging the spatial and depth capabilities of 3D convolutional neural networks, our method is specifically designed to recognize patterns and features in three-dimensional space, making it uniquely suited for rejecting false-positive sources in low SNR scenarios generated by conventional linear methods. As a result, our approach is significantly more accurate in source detection and results in considerably fewer false detections compared to previous linear statistics-based source finding algorithms. Performance tests using mock galaxies injected into real ASKAP data cubes reveal our method’s capability to achieve near-100% completeness and reliability at a relatively low integrated SNR $\sim3-5$. An at-scale version of this tool will greatly maximise the science output from the upcoming widefield Hi surveys.

Electron microscopy is uniquely suited for atomic-resolution imaging of heterogeneous and complex materials, where composition, physical, and electronic structure need to be analyzed simultaneously. Historically, the technique has demonstrated optimal performance at room temperature, since practical aspects such as vibration, drift, and contamination limit exploration at extreme temperature regimes. Conversely, quantum materials that exhibit exotic physical properties directly tied to the quantum mechanical nature of electrons are best studied (and often only exist) at extremely low temperatures. As a result, emergent phenomena, such as superconductivity, are typically studied using scanning probe-based techniques that can provide exquisite structural and electronic characterization, but are necessarily limited to surfaces. In this article, we focus not on the various methods that have been used to examine quantum materials at extremely low temperatures, but on what could be accomplished in the field of quantum materials if the power of electron microscopy to provide structural analysis at the atomic scale was extended to extremely low temperatures.

For over 120 years, the shell middens of western Scotland and the series of open-air sites on Oronsay have been the focus of debate in European Mesolithic studies. This paper challenges the significance of Oronsay in light of results from the geophysical survey and test-excavation of a new limpet and periwinkle shell midden dated to the late 5th or start of the 4th millennium cal bc at Port Lobh, Colonsay that offers fresh evidence to re-evaluate critically the role of Oronsay and coastal resources in island settlement models ahead of the Mesolithic–Neolithic transition. Test excavations recovered a marine molluscan assemblage dominated by limpet and periwinkle shells together with crab, sea urchin, a fishbone assemblage composed mainly of Gadidae, some identifiable bird and mammal bone, carbonised macroplant remains, and pumice as well as a bipolar lithic assemblage and coarse stone implements. Novel seasonality studies of saithe otolith thin-sections suggest wintertime tidal fishing practices. At least two activity events may be discerned, dating from the late 5th millennium cal bc. The midden could represent a small number of rapidly deposited assemblages or maybe the result of stocastic events within a more extended timeframe. We argue that alternative research questions are needed to advance long-standing debates about seasonal inter-island mobility versus island sedentism that look beyond Oronsay to better understand later Mesolithic occupation patterns and the formation and date of Oronsay middens. We propose alternative methodological strategies to aid identification of contemporaneous sites using geophysical techniques and lithic technological signatures.