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We present the first joint spectral and imaging analysis of hard X-ray (HXR) emission from three microflares observed by the Nuclear Spectroscopic Telescope ARray (NuSTAR) and Solar Orbiter/Spectrometer/Telescope for Imaging X-rays (STIX). We studied 5 joint spectra from GOES A7, B1, and B6 class microflares from active region AR12765 on 2020 June 6 and 7. As these events are very bright for NuSTAR, resulting in extremely low (<1 per cent) livetime, we introduce a pile-up correction method. All five joint spectra were fitted with an isothermal model finding temperatures in the 9–11 MK range. Furthermore, three joint spectra required an additional non-thermal thick-target model finding non-thermal powers of |$10^{25}$| – |$10^{26}$| erg s |$^{-1}$|⁠. All the fit parameters were within the ranges expected for HXR microflares. The fit results give a relative scaling of STIX and NuSTAR mostly between 6 and 28 per cent (one outlier at 52 per cent) suggesting each instrument are well calibrated. In addition to spectral analysis, we performed joint HXR imaging of the June 6 and one of the June 7 microflares. In NuSTAR's field of view (FOV), we observed two separate non-thermal sources connected by an elongated thermal source during the June 6 microflares. In STIX's FOV (44 |$^{\circ }$| W with respect to NuSTAR), we imaged thermal emission from the hot flare loops which when reprojected to an Earth viewpoint matches the thermal sources seen with NuSTAR and in the hotter EUV channels with the Solar Dynamic Observatory's Atmospheric Imaging Assembly. [ABSTRACT FROM AUTHOR]

The retrosplenial cortex (RSC) is a key component of the brain's memory systems, with anatomical connections to the hippocampus, anterior thalamus, and entorhinal cortex. This circuit has been implicated in episodic memory and many of these structures have been shown to encode temporal information, which is critical for episodic memory. For example, hippocampal time cells reliably fire during specific segments of time during a delay period. Although RSC lesions are known to disrupt temporal memory, time cells have not been observed there. In this study, we reanalyzed archival RSC neuronal firing data during the intertrial delay period from two previous experiments involving different behavioral tasks, a blocked alternation task and a cued T‐maze task. For the blocked alternation task, rats were required to approach the east or west arm of a plus maze for reward during different blocks of trials. Because the reward locations were not cued, the rat had to remember the goal location for each trial. In the cued T‐maze task, the reward location was explicitly cued with a light and the rats simply had to approach the light for reward, so there was no requirement to hold a memory during the intertrial delay. Time cells were prevalent in the blocked alternation task, and most time cells clearly differentiated the east and west trials. We also found that RSC neurons could exhibit off‐response time fields, periods of reliably inhibited firing. Time cells were also observed in the cued T‐maze, but they were less prevalent and they did not differentiate left and right trials as well as in the blocked alternation task, suggesting that RSC time cells are sensitive to the memory demands of the task. These results suggest that temporal coding is a prominent feature of RSC firing patterns, consistent with an RSC role in episodic memory. [ABSTRACT FROM AUTHOR]

The hippocampus (HPC) and retrosplenial cortex (RSC) are key components of the brain's memory and navigation systems. Lesions of either region produce profound deficits in spatial cognition and HPC neurons exhibit well‐known spatial firing patterns (place fields). Recent studies have also identified an array of navigation‐related firing patterns in the RSC. However, there has been little work comparing the response properties and information coding mechanisms of these two brain regions. In the present study, we examined the firing patterns of HPC and RSC neurons in two tasks which are commonly used to study spatial cognition in rodents, open field foraging with an environmental context manipulation and continuous T‐maze alternation. We found striking similarities in the kinds of spatial and contextual information encoded by these two brain regions. Neurons in both regions carried information about the rat's current spatial location, trajectories and goal locations, and both regions reliably differentiated the contexts. However, we also found several key differences. For example, information about head direction was a prominent component of RSC representations but was only weakly encoded in the HPC. The two regions also used different coding schemes, even when they encoded the same kind of information. As expected, the HPC employed a sparse coding scheme characterized by compact, high contrast place fields, and information about spatial location was the dominant component of HPC representations. RSC firing patterns were more consistent with a distributed coding scheme. Instead of compact place fields, RSC neurons exhibited broad, but reliable, spatial and directional tuning, and they typically carried information about multiple navigational variables. The observed similarities highlight the closely related functions of the HPC and RSC, whereas the differences in information types and coding schemes suggest that these two regions likely make somewhat different contributions to spatial cognition. [ABSTRACT FROM AUTHOR]

Background Respiratory syncytial virus (RSV) is a major cause of morbidity and mortality among US infants. A child's calendar birth month determines their age at first exposure(s) to RSV. We estimated birth month-specific risk of medically attended (MA) RSV lower respiratory tract infection (LRTI) among infants during their first RSV season and first year of life (FYOL). Methods We analyzed infants born in the USA between July 2016 and February 2020 using three insurance claims databases (two commercial, one Medicaid). We classified infants' first MA RSV LRTI episode by the highest level of care incurred (outpatient, emergency department, or inpatient), employing specific and sensitive diagnostic coding algorithms to define index RSV diagnoses. In our main analysis, we focused on infants' first RSV season. In our secondary analysis, we compared the risk of MA RSV LRTI during infants' first RSV season to that of their FYOL. Results Infants born from May through September generally had the highest risk of first-season MA RSV LRTI—approximately 6–10% under the specific RSV index diagnosis definition and 16–26% under the sensitive. Infants born between October and December had the highest risk of RSV-related hospitalization during their first season. The proportion of MA RSV LRTI events classified as inpatient ranged from 9% to 54% (specific) and 5% to 33% (sensitive) across birth month and comorbidity group. Through the FYOL, the overall risk of MA RSV LRTI is comparable across birth months within each claims database (6–11% under the specific definition, 17–30% under the sensitive), with additional cases progressing to care at outpatient or ED settings. Conclusions Our data support recent national recommendations for the use of nirsevimab in the USA. For infants born at the tail end of an RSV season who do not receive nirsevimab, a dose administered prior to the onset of their second RSV season could reduce the incidence of outpatient- and ED-related events. [ABSTRACT FROM AUTHOR]

During the 2022 New Mexico monsoon season, we deployed two X‐ray scintillation detectors, coupled with a 180 MHz data acquisition system to detect X‐rays from natural lightning at the Langmuir Lab mountain‐top facility, located at 3.3 km above mean sea level. Data acquisition was triggered by an electric field antenna calibrated to pick up lightning within a few km of the X‐ray detectors. We report the energies of over 240 individual photons, ranging between 13 keV and 3.8 MeV, as registered by the LaBr3(Ce) scintillation detector. These detections were associated with four lightning flashes. Particularly, four‐stepped leaders and seven dart leaders produced energetic radiation. The reported photon energies allowed us to confirm that the X‐ray energy distribution of natural stepped and dart leaders follows a power‐law distribution with an exponent ranging between 1.09 and 1.96, with stepped leaders having a harder spectrum. Characterization of the associated leaders and return strokes was done with four different electric field sensing antennas, which can measure a wide range of time scales, from the static storm field to the fast change associated with dart leaders. Plain Language Summary: During the 2022 monsoon season in New Mexico, Langmuir Lab scientists used special X‐ray detectors to study natural lightning over a mountain‐top facility. The team detected X‐ray emissions from 4 natural lightning flashes. The X‐rays are produced by the lightning precursor stage, called leader. Leaders travel long distances in the atmosphere and carve the way for lightning to transfer charge from the cloud to ground. After careful inspection of the energy content of the X‐ray photons, the team concluded that leaders traveling in virgin air, known as stepped leaders, emit more energetic X‐rays than leaders retracing previously established lightning channels, called dart leaders. Key Points: 5‐ns resolution allowed for the measurement of individual X‐ray photon energies from natural lightning and to confirm its power‐law spectrumStepped leader X‐rays come in a train of bursts lasting milliseconds, while dart leader X‐rays come effectively in a single burstStepped leaders have a harder energy spectrum than dart leaders, with a larger population of >1 MeV photons [ABSTRACT FROM AUTHOR]

As part of the final year of their undergraduate degree programmes, some chemistry students at the University of Bristol spend time in local primary or secondary schools working on chemistry or chemical education problems. All partners gain from this programme. The students develop many of the transferable skills required by employers in all sectors. The scheme also provides them with the chance to gain some experience of working in schools, at the same time as acquiring credit as part of their degree programme. Many of the participating students go on to postgraduate teacher training courses and become committed and effective teachers. The schools benefit from having young enthusiastic science role models, assistance in the classroom and an opportunity to develop and run new projects. The scheme also helps the university department develop better links with neighbouring schools.

We present analysis on two X-ray bright points observed over several hours during the recent solar minimum (2020 February 21 and 2020 September 12–13) with the Nuclear Spectroscopic Telescope Array (NuSTAR), a sensitive hard X-ray imaging spectrometer. This is so far the most detailed study of bright points in hard X-rays, emission which can be used to search for faint hot and/or non-thermal sources. We investigate the bright points' time evolution with NuSTAR, and in extreme ultraviolet (EUV) and soft X-rays with Solar Dynamic Observatory/Atmospheric Imaging Assembly (SDO/AIA) and Hinode/X-Ray Telescope. The variability in the X-ray and EUV time profiles is generally not well matched, with NuSTAR detecting spikes that do not appear in EUV. We find that, for the 2020 February bright point, the increased X-ray emission during these spikes is due to material heated to ∼ 4.2–4.4 MK (found from fitting the X-ray spectrum). The 2020 September bright point also shows spikes in the NuSTAR data with no corresponding EUV signature seen by SDO/AIA, though in this case, it was due to an increase in emission measure of material at ∼ 2.6 MK and not a significant temperature change. So, in both cases, the discrepancy is likely due to the different temperature sensitivity of the instruments, with the X-ray variability difficult to detect in EUV due to cooler ambient bright point emission dominating. No non-thermal emission is detected, so we determine upper limits finding that only a steep non-thermal component between 3 and 4 keV could provide the required heating whilst being consistent with a null detection in NuSTAR. [ABSTRACT FROM AUTHOR]

Established model theories, developed to capture the mechanical behavior of soft, complex materials composed of semiflexible polymers, assume that entropic interactions between filaments are primarily responsible for determining the mechanical response. In recent studies, the generally accepted tube model has been challenged in terms of this basic assumption about filament–filament interactions, but also because of its predictions regarding the frequency dependence of the elastic modulus in the intermediate frequency regime. A central question is how molecular interactions and friction between network constituents influence the rheological response of isotropic entangled networks of semiflexible polymers. It has been previously shown that friction forces between aligned pairs of actin filaments are not negligible. Here, the influence of friction forces and attractive interactions on network rheology is systematically investigated by means of targeted surface modification. It is shown that these forces have a qualitative and quantitative influence on the viscoelastic properties of semiflexible polymer networks and contribute to their response to nonlinear deformations. By comparing two polymer model systems with respect to their surface compositions, a possible explanation is given about the origin of acting forces on a molecular level. [ABSTRACT FROM AUTHOR]

We report on the mountain top observation of three terrestrial gamma‐ray flashes (TGFs) that occurred during the summer storm season of 2021. To our knowledge, these are the first TGFs observed in a mountaintop environment and the first published European TGFs observed from the ground. A gamma‐ray sensitive detector was located at the base of the Säntis Tower in Switzerland and observed three unique TGF events with coincident radio sferic data characteristic of TGFs seen from space. We will show an example of a "slow pulse" radio signature (Cummer et al., 2011, https://doi.org/10.1029/2011GL048099; Lu et al., 2011, https://doi.org/10.1029/2010JA016141; Pu et al., 2019, https://doi.org/10.1029/2019GL082743; Pu et al., 2020, https://doi.org/10.1029/2020GL089427), a −EIP (Lyu et al., 2016, https://doi.org/10.1002/2016GL070154; Lyu et al., 2021, https://doi.org/10.1029/2021GL093627; Wada et al., 2020, https://doi.org/10.1029/2019JD031730), and a double peak TGF associated with an extraordinarily powerful and complicated positive‐polarity sferic, where each TGF peak is possibly preceded by a short burst of stepped leader emission. Plain Language Summary: We present the first report of mountain top observations of terrestrial gamma‐ray flashes (TGFs) that occurred during the summer storm season of 2021. A gamma‐ray sensitive detector was placed at the base of the Säntis Tower in Switzerland and detected three distinct TGF events. Each event is associated with a coincident lightning flash. We analyze the radio emission of the associated lightning flash and make comparisons with previously published associations between TGFs and certain radio sferics. Additionally, one of the observed TGFs is likely a two‐pulse event where each gamma‐ray peak may be preceded in time by a brief burst of X‐ray stepped leader emission. Key Points: First terrestrial gamma ray flashe (TGF) observations from a mountaintopFirst ground observation of a TGF associated with a "slow pulse" radio sfericPossible stepped leader X‐rays preceding a double pulsed TGF [ABSTRACT FROM AUTHOR]

We observed two Terrestrial Gamma‐ray Flashes (TGFs) in Uchinada, Japan associated with negative cloud‐to‐ground lightning strokes exactly 1 year apart on 18 December 2020 and 2021. The events were remarkable for their lateral distance from the associated strokes—each about 5 km away from the detector site. Not only was that lateral distance remarkable on its own for a ground based detection, but the low‐altitude profile of winter thunderstorms in Japan would suggest the detections occurred at unprecedented nadir angles—73.3° off axis for the 2020 event with the standard assumption of a vertically oriented TGF. Unsurprisingly, Monte Carlo simulations of the straightforward interpretation of these events yield fluences 2 orders of magnitude lower than observed data. We investigate a variety of ways to attempt to resolve the contradiction between expected and observed behavior. Plain Language Summary: We observed two terrestrial gamma‐ray flashes at a distance and angle from which we should have seen nothing given our current understanding of how bright and wide these events can be. We investigate what must have been different about these events to make them visible to our detectors. Key Points: We detected two downward TGFs in Uchinada, Japan, approximately 5 km away laterally from the associated lightning flash's ground strike pointEstimates of the altitude of the tops of the associated leader channels from radio, optical, and climate data suggest we were, remarkably, up to 73.3° off of the vertical axes of the TGFsMonte Carlo simulations show our observations were 1–2 orders of magnitude brighter than what would be expected from a standard TGF at that geometry [ABSTRACT FROM AUTHOR]

To assist in the speed and accuracy of designing brick-based DNA nanostructures, we introduce a lightweight software suite 3DNA that can be used to generate complex structures. Currently, implementation of this fabrication strategy involves working with generalized, typically commercial CAD software, ad-hoc sequence-generating scripts, and visualization software, which must often be integrated together with an experimental lab setup for handling the hundreds or thousands of constituent DNA sequences. 3DNA encapsulates the solutions to these challenges in one package by providing a customized, easy-to-use molecular canvas and back-end functionality to assist in both visualization and sequence design. The primary motivation behind this software is enabling broader use of the brick-based method for constructing rigid, 3D DNA-based nanostructures, first introduced in 2012. 3DNA is developed to provide a streamlined, real-time workflow for designing and implementing this type of 3D nanostructure by integrating different visualization and design modules. Due to its cross-platform nature, it can be used on the most popular desktop environments, i.e., Windows, Mac OS X, and various flavors of Linux. 3DNA utilizes toolbar-based navigation to create a user-friendly GUI and includes a customized feature to analyze the constituent DNA sequences. Finally, the oligonucleotide sequences themselves can either be created on the fly by a random sequence generator, or selected from a pre-existing set of sequences making up a larger molecular canvas. [ABSTRACT FROM AUTHOR]