Large Magnitude Research Articles

Substantial Increase in Sub–Daily Precipitation Extremes of Flooding Season Over China

AbstractUnderstanding sub‐daily precipitation extremes (SPEs) can provide scientific insights for taking effective measures to mitigate climate risks. Leveraging gauge observations at hourly precipitation in 2,312 meteorological stations and extreme sub‐daily precipitation indices (ESPIs), we investigate the changes of SPEs in flooding season of 1971–2022 in China. On country scale, the occurrences and intensity of SPEs have significantly increased and even accelerated since the 21st century, suggesting increases in 2010s by 15%–38% compared with that in 1970s. The SPE risks for 20‐year and 50‐year return‐period increased by 2–4 and 8–20 times in 2001–2022 compared with that in 1971–2000, respectively. Over 80% stations are found to have positive trends in all ESPIs. On regional scale, seven sub‐regions experienced significant increases in ESPIs with larger magnitudes in the East China. The enlarged 500‐hPa geopotential height, 700‐hPa pseudoequivalent potential temperature, 700‐hPa specific humidity, saturated vapor pressure and urbanization ratio may be bonded to more SPEs.

High–Field EPR Studies on Three Binuclear μ–Oxo–Bridged Iron(III) Complexes: Na4[Fe(edta)]2O ⋅ 3H2O, [Fe(phen)2(H2O)]2O(NO3)4 ⋅ 5H2O and [Fe(salen)]2O

AbstractA High–Field, High–Frequency Electron Paramagnetic Resonance (HFEPR) study was performed on the binuclear μ–oxo bridged complexes Na4[Fe(edta)]2O ⋅ 3H2O, [Fe(phen)2(H2O)]2O(NO3)4 ⋅ 5H2O and [Fe(salen)]2O, where edtaH4 = ethylenediaminetetraacetic acid, phen=1,10–phenanthroline and salenH2 is NN′–ethylenebis(salicylideneimine). The spin Hamiltonian parameters were determined for the thermally excited spin states with spin S=1, 2 and 3. The contributions to the zero–field splitting due to the local zero field splitting on individual iron ions and to the anisotropic metal–metal interactions were evaluated. Surprisingly large magnitudes of the anisotropic exchange interactions were found.

Force Field Limitations of All-Atom Continuous Constant pH Molecular Dynamics.

All-atom constant pH molecular dynamics simulations offer a powerful tool for understanding pH-mediated and proton-coupled biological processes. As the protonation equilibria of protein side chains are shifted by electrostatic interactions and desolvation energies, pKa values calculated from the constant pH simulations may be sensitive to the underlying protein force field and water model. Here we investigated the force field dependence of the all-atom particle mesh Ewald (PME) continuous constant pH (PME-CpHMD) simulations of a mini-protein BBL. The replica-exchange titration simulations based on the Amber ff19sb and ff14sb force fields with the respective water models showed significantly overestimated pKa downshifts for a buried histidine (His166) and for two glutamic acids (Glu141 and Glu161) that are involved in salt-bridge interactions. These errors (due to undersolvation of neutral histidines and overstabilization of salt bridges) are consistent with the previously reported pKa's based on the CHARMM c22/CMAP force field, albeit in larger magnitudes. The pKa calculations also demonstrated that ff19sb with OPC water is significantly more accurate than ff14sb with TIP3P water, and the salt-bridge related pKa downshifts can be partially alleviated by the atom-pair specific Lennard-Jones corrections (NBFIX). Together, these data suggest that the accuracies of the protonation equilibria of proteins from constant pH simulations can significantly benefit from improvements of force fields.

Abstract 4120290: Sex-specific Impact of Early to Mid-gestational Testosterone Excess on Sheep Fetal and Adult Offspring Lungs

Using the translationally relevant sheep model of prenatal testosterone (T) excess, we previously reported intrauterine growth retardation (IUGR) in both sexes, adverse sex specific programming of fetal heart and cardiometabolic dysfunction in adult female offspring. Because of the intricate reciprocal relationship between the heart and lungs, we hypothesized that gestational T excess will have detrimental sex-specific effects on offspring lungs beginning as early as fetal life and extending into adulthood. Pregnant ewes were intramuscularly injected with 100 mg of testosterone propionate twice weekly from gestational days (GD) 30-90 (term 147 days) and offspring lungs were harvested at GD120, 30 days after cessation of T treatment; (n=4-7/group) and in adulthood (n=4-6/group) and processed for molecular and histological analyses. Data was analyzed by student T test within each sex and Cohen (d) effect size was calculated (Cohens d>0.8 represents large effect size. Lung collagen was significantly increased in T-male fetuses (TM) vs control males (CM) (p=0.01, d=1.99) that persisted into adulthood (TM vs CM: p=0.01, d=1.83). The effects of gestational T excess was evidenced as an increase in collagen only in the lungs of adult T-female fetuses (TF) relative to control females (CF) (p=0.003, d=2.38), but not during fetal life. Gestational T excess induced significant parallel increases in TUNEL positive nuclei/frame in TM fetuses relative to CM (n=3/group, p=0.01, d=3.35) persisting as a large magnitude increase of TUNEL positive nuclei/frame in adult TM (p=0.12, d=0.96). In TF females, apoptotic changes were not noted in fetal lungs but an increase of TUNEL positive nuclei/frame was evidenced in adult TF (p=0.08, d=1.14). At the molecular level prenatal T excess induced an increase in histone deacetylase 1 (HDAC1) expression in fetal TM vs CM (p=0.04, d=1.50), and decrease in HDAC1 in TF vs CF (p=0.10, d=1.09) suggestive of T-induced epigenetic alteration. Transcriptomic analysis of fetal lungs revealed upregulation of pathways associated with estrogen signaling and neuroactive ligand receptor interaction, and downregulation of pathways associated with protein processing in endoplasmic reticulum and antigen processing&presentation (unadjusted p< 0.05, log FC>1.5) in both sexes. Overall, early to mid-gestational exposure to testosterone adversely reprograms the lungs in sex specific fashion as early as fetal life extending into postnatal adult life.

Investigation of co-seismic stress and aftershock distribution along the Sumatra–Andaman subduction zone

AbstractThis study aimed to investigate co-seismic stress and aftershock distribution along the Sumatra–Andaman subduction zone (SASZ). The fault parameters of six major earthquakes with an M ≥ 7 that occurred during 2010–2022 along the SASZ, were utilized to determine the Coulomb stress change using numerical modeling techniques calculated on the receiver faults with similar focal mechanisms of the mainshock, strike-slip, thrust, and normal faulting, respectively. The earthquake events were then classified to analyze the aftershocks of major earthquakes in the area. These aftershocks were mapped in order to determine the relationship between the aftershock distribution and the areas of increased or decreased stress. The relationship between the co-seismic stress and distribution of aftershocks in the SASZ was found to mainly depend on the focal mechanism of major earthquakes and the type of receiver fault used for calculation. After a major earthquake in the SASZ, there are two possible patterns that most aftershocks will be generated from in the areas of increased stress. First, a major earthquake is a type of thrust fault calculated on the receiver fault using the focal mechanism of the mainshock. Second, a major earthquake is a type of strike-slip fault calculated on the receiver fault with an optimum-oriented strike-slip fault. This relationship is likely to represent the specific pattern of the seismotectonic stress in the SASZ that can be used to evaluate the risk areas of aftershocks after a major earthquake has occurred. Furthermore, two earthquake events with large magnitudes were generated following the respective major earthquake in the SASZ that were located around the areas of increased stress, indicating that these two earthquake events were likely triggered in areas of increased stress following the respective major earthquake. Therefore, this study concluded that after a major earthquake occurrence in the SASZ, the areas of increased stress have a higher risk of generating both a large number of aftershocks and a new large-magnitude mainshock event. The investigation of co-seismic stress is very important to estimate areas of increased stress after a major earthquake, as this can be useful for monitoring both earthquake and tsunami hazards in the area.

How Do Surgical Interventions for Neurogenic Lower Urinary Tract Dysfunction Impact Quality of Life?

Adult patients with neurogenic lower urinary tract dysfunction (NLUTD) often have urinary symptoms that impact their quality of life (QOL). Our objective is to identify and summarize studies evaluating QOL changes across different NLUTD surgical interventions. A systematic rapid evidence review was carried using EMBASE and MEDLINE. We included adult patients (> 18 years old) with NLUTD who underwent a relevant surgery and had a measurement of QOL. We included pre-post study designs (primary focus) and cross-sectional studies (secondary focus). Studies were reviewed and data extracted by multiple assessors. Standardized data extraction tables were used, and qualitative synthesis was performed. Of the 1074 screened articles 26 were included. There were 3/15 studies that evaluated reconstructive surgery (augmentation and/or catheterisable channel) pre-post intervention (n = 94 patients); there was a 7%-28% relative improvement in bladder related and overall QOL using validated questionnaires, and a large magnitude of improvement in studies using unvalidated questionnaires. There were 3/7 studies that looked at urinary diversion pre-post intervention (n = 153 patients) and showed an approximately 20%-60% improvement in validated questionnaires assessing bladder specific quality of life, and 0%-25% improvement in overall quality of life. Finally, 3/4 studies were pre-post stress incontinence surgeries (n = 67 patients) and they found an improvement in the ICIQ questionnaire scores and study-specific questionnaires. The literature supporting a change in QOL in adult NLUTD patients undergoing surgical interventions is extremely limited due to a lack of pre-post studies, and the frequent use of unvalidated outcome measures.

Horizontal QRS Axis Predicts Response to Cardiac Resynchronization Therapy in Heart Failure Patients with Left Bundle Branch Block

Electrocardiogram criteria for left bundle branch block (LBBB) inadequately predict left ventricular electrical dyssynchrony, complicating cardiac resynchronization therapy (CRT) candidate selection. To investigate the predictive value of the horizontal QRS axis for CRT response in heart failure (HF) patients with LBBB patterns. The direction and magnitude of the horizontal QRS axis were calculated using the net amplitudes in leads V2 and V6. CRT response was defined as a ≥10% increase in left ventricular ejection fraction (LVEF) and at least one New York Heart Association (NYHA) class reduction one-year post-CRT implantation. The composite endpoint included HF hospitalization or all-cause mortality. Among 244 consecutive CRT recipients, 156 (63.9%) responded favorably, while 88 (36.1%) were non-responders. The horizontal QRS axis demonstrated significant backward deviation [-75.5° (-79.7°, -69.0°) vs. -65.0° (-73.0°, -46.5°), P <0.001] and larger magnitude (35.5±10.9 mm vs. 25.5±10.5 mm, P <0.001) in CRT responders compared to non-responders. The direction and magnitude independently predicted CRT response with an area under the curve (AUC) of 0.778 (95% CI: 0.717, 0.839) and 0.749 (95% CI: 0.685, 0.814), respectively. Combining both parameters increased the AUC to 0.814 (95% CI: 0.760, 0.868). Moreover, the direction and magnitude of the horizontal QRS axis, or their combination, predicted the composite endpoint of HF hospitalization or all-cause mortality, with hazard ratios (HR) of 0.36 (95% CI: 0.22, 0.60), 0.41 (95% CI: 0.25, 0.67), and 0.25 (95% CI: 0.15, 0.41), respectively. Horizontal QRS axis accurately predicts CRT response and prognosis in HF patients with LBBB.

Evaluation of the Multidimensional Personality Questionnaire (MPQ) Unlikely Virtues Scale in the detection of underreporting.

The current investigation was designed to examine the impact of underreporting response bias on the Multidimensional Personality Questionnaire (MPQ) and the utility of the Unlikely Virtues scale in detecting such responding. Study participants were randomly assigned to either the underreporting (n = 100) or standard instruction (n = 224) conditions. All participants first completed a series of extratest measures under standard instruction prior to the MPQ administration. The results showed that individuals in the underreporting condition scored significantly higher on MPQ scales that reflect positive emotionality and self-control and lower on scales that indicate negative emotionality compared to those in the standard instruction. Moreover, the psychometric validity of MPQ scale scores against extratest measures was substantially attenuated in the underreporting condition compared to the standard instruction condition. The Unlikely Virtues scale differentiated between the conditions at a large effect size magnitude (Hedges' g = 1.21) and showed promising classification accuracy though lower cut scores than those reported in the MPQ manual performed substantially better with respect to sensitivity. Future research needs to replicate these findings in more naturalistic settings with other research designs. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Micronutrients and Major Depression: A Mendelian Randomisation Study.

Various vitamins and minerals have been implicated in the aetiology of depression. To estimate the effects of micronutrient exposures on major depressive disorder (MDD) and recurrent depression (rMDD) using Mendelian randomisation (MR), a method using genetic data to estimate causal effects given certain assumptions. We undertook a comprehensive bidirectional MR study of multiple micronutrient exposures on MDD and rMDD. Summary statistics were obtained from the Psychiatric Genomics Consortium (PGC) genome-wide association studies (GWASs) of MDD (cases = 116,209; controls = 314,566) and rMDD (cases = 17,451; controls = 62,482). None of the micronutrients with available genetic instruments were strongly associated with MDD or rMDD using traditional MR methods. However, using methods to increase analytical power by accounting for genetically correlated variants (e.g., cIVW) highlighted five micronutrients with possible causal effects. Point estimates for rMDD were the largest magnitude, with three micronutrients suggestive of a protective effect: serum iron (ORcIVW 0.90 per SD increase; 95% CI 0.85-0.95; p = 0.0003); erythrocyte copper (ORcIVW 0.97; 95% CI 0.95-0.99; p = 0.0004); and 25(OH) vitamin D (ORcIVW 0.81; 0.66-0.99; p = 0.04). Apparent adverse effects of increased selenium on the risk of MDD (ORcIVW 1.03; 95% CI 1.02-1.05; p = 0.0003) and rMDD (ORcIVW 1.08; 95% CI 1.00-1.08; p = 0.06), and serum magnesium on rMDD (ORcIVW 1.21; 1.01-1.44; p = 0.04); were less consistent between methods and may be driven by pleiotropy. Our results suggest weak evidence for a protective effect of iron, copper and 25(OH)D on major depressive outcomes, with mixed evidence for selenium and magnesium. There was no evidence to support a causal effect of any other micronutrients on MDD or rMDD, although genetic instruments were lacking, with insufficient power to detect small but important effects. Future micronutrient supplementation trials should ensure ample statistical power given modest causal effect estimates and consider potential risks of supplementation, as some micronutrient effect estimates suggested potential harm in excess.

Activation of Ms 6.9 Milin Earthquake on Sedongpu Disaster Chain, China with Multi-Temporal Optical Images

In recent years, disaster chains caused by glacier movements have occurred frequently in the lower Yarlung Tsangpo River in southwest China. However, it is still unclear whether earthquakes significantly contribute to glacier movements and disaster chains. In addition, it is difficult to measure the high-frequency and large gradient displacement time series with optical remote sensing images due to cloud coverage. To this end, we take the Sedongpu disaster chain as an example, where the Milin earthquake, with an epicenter 11 km away, occurred on 18 November 2017. Firstly, to deal with the cloud coverage problem for single optical remote sensing analysis, we employed multiple platform optical images and conducted a cross-platform correlation technique to invert the two-dimensional displacement rate and the cumulative displacement time series of the Sedongpu glacier. To reveal the correlation between earthquakes and disaster chains, we divided the optical images into three classes according to the Milin earthquake event. Lastly, to increase the accuracy and reliability, we propose two strategies for displacement monitoring, that is, a four-quadrant block registration strategy and a multi-window fusion strategy. Results show that the RMSE reduction percentage of the proposed registration method reaches 80%, and the fusion method can retrieve the large magnitude displacements and complete displacement field. Secondly, the Milin earthquake accelerated the Sedongpu glacier movement, where the pre-seismic velocities were less than 0.5 m/day, the co-seismic velocities increased to 1 to 6 m/day, and the post-seismic velocities decreased to 0.5 to 3 m/day. Lastly, the earthquake had a triggering effect around 33 days on the Sedongpu disaster chain event on 21 December 2017. The failure pattern can be summarized as ice and rock collapse in the source area, large magnitude glacier displacement in the moraine area, and a large volume of sediment in the deposition area, causing a river blockage.

Investigation of local soil properties of Erzurum province (Eastern Türkiye) by Horizontal/Vertical Spectral ratio method

Erzurum province is a basin developed under the effect of strike-slip faults in the Eastern Anatolia region. Erzurum province is generally influenced by the left strike-slip Erzurum Fault Zone, the left- strike-slip Aşkale fault, and the Başköy-Kandilli reverse fault. It is also located approximately 80 km from the Karlıova joint, which is the intersection of the North Anatolian and East Anatolian Faults. When the earthquakes of the instrumental and historical periods are analyzed, it is seen that many damaging earthquakes of medium to large magnitude have occurred in Erzurum province. Erzurum basin is generally covered with old alluvium at the edges of the plains, while the flat areas in the central parts are covered with new alluvium. Determination of local soil properties in regions with high earthquake hazard plays an important role in reducing earthquake risks. For this purpose, single station microtremor measurements were applied at 25 sites in Palandöken and Yakutiye districts of Erzurum province. The measurements were taken for at least 30 minutes and evaluated according to the Horizontal/Vertical Spectral Ratio method. As a result of the analysis, the dominant period, H/V ratio and vulnerability index (Kg) values of the measurement points were calculated. The period values obtained vary between 0.15 s and 3.7 s, while the H/V ratios vary between 2.2 and 8.5. The Kg value obtained using these parameters is defined as the vulnerability of the soil. It is concluded that high period, high H/V and high Kg values are obtained in areas with recent alluvium and multidisciplinary analyses should be performed in soil investigations in these regions.

Intensification of submesoscale frontogenesis and forward energy cascade driven by upper-ocean convergent flows

Upper-ocean fronts are an important component of the global climate system, regulating both the oceanic energy cycle and material transports. In the common paradigm, upper-ocean fronts are generated by frontogenesis at the mesoscale (20–300 km), driven predominantly by confluent horizontal flows initiated by a background straining field. However, the mechanisms by which this frontogenesis extends down to and influences the submesoscale (0.2–20 km), which dominates vertical transports in the ocean, are still understudied. Here, we provide direct observational evidence that submesoscale frontogenesis, defined as the rate at which submesoscale buoyancy gradients intensify, is closely linked to convergent flows. Analysis of year-long measurements by a mooring array in the North Atlantic indicates that both the upper-ocean frontogenetic rate and the horizontal convergence exhibit strong seasonality and scale dependence, with larger magnitudes in winter and at smaller horizontal scales (down to at least 2 km). The frontogenetic rate is found to correlate more strongly with horizontal convergence as the scale decreases, suggesting that convergent flows are the main driver of submesoscale frontogenesis. Crucially, a rapid forward cascade of kinetic energy and enhanced vertical velocities preferentially occur during periods of submesoscale frontogenesis. Our findings highlight a mechanism underpinning the key role of submesoscale fronts in the oceanic kinetic energy cascade and as a focus of vertical transports, and call for a parameterization of such effects in climate-scale ocean models.

Maternal Glycemic Status and Longitudinal Fetal Body Composition and Organ Volumes Based on Three-Dimensional Ultrasonography.

Gestational diabetes mellitus (GDM) increases the risk of fetal overgrowth as measured by two-dimensional ultrasonography. Whether fetal three-dimensional (3D) soft tissue and organ volumes provide additional insight into fetal overgrowth is unknown. We prospectively evaluated longitudinal 3D fetal body composition and organ volumes in a diverse US singleton pregnancy cohort (2015-2019). Women were diagnosed with GDM, impaired glucose tolerance (IGT), or normal glucose tolerance (NGT). Up to five 3D ultrasound scans measured fetal body composition and organ volumes; trajectories were modeled using linear mixed models. Overall and weekly mean differences in fetal 3D trajectories were tested across glycemic status, adjusted for covariates. In this sample (n = 2,427), 5.2% of women had GDM, and 3.0% had IGT. Fetuses of women who developed GDM compared with NGT had larger fractional arm and fractional fat arm volumes from 26 to 35 weeks, smaller fractional lean arm volume from 17 to 22 weeks, and larger abdominal area from 24 to 40 weeks. Fetuses of women with IGT had similar growth patterns, which manifested later in gestation and with larger magnitudes, and had larger fractional lean arm volume. No overall differences were observed among thigh or organ volumes across glycemic status. Body composition differed in fetuses of GDM-complicated pregnancies, including larger arm and abdominal measures across the second and third trimesters. Patterns were similar in IGT-complicated pregnancies except that they occurred later in gestation and with larger magnitudes. Future research should explore how lifestyle and medication may alter fetal fat accumulation trajectories among hyperglycemic pregnancies.

Scale-dependent inflation algorithms for ensemble Kalman filters

Abstract Ensemble-based data assimilation methods often suffer sampling errors due to limited ensemble sizes and model errors, which can result in filter divergence. One method to avoid filter divergence is inflation, which inflates ensemble perturbations to increase ensemble spread and account for model errors. The commonly applied inflation methods, including the multiplicative inflation, relax to prior spread (RTPS), and additive inflation, often use a constant inflation parameter. To capture different error growths at different scales, a scale-dependent inflation is proposed here, which applies different inflation magnitudes for variables associated with different scales. Results from the two-scale Lorenz05 model III show that for the ensemble square-root filter (EnSRF) and integrated hybrid ensemble Kalman filter with ensemble mean updated by hybrid background error covariances (IHEnKF-Mean), scale-dependent inflation is superior to constant inflation. Constant inflation overinflates small-scale variables and results in increased small-scale errors, which then propagate to large-scale variables through the coupling between large- and small-scale variables and lead to increased large-scale errors. Scale-dependent inflation applies larger inflation for large-scale variables and imposes no inflation for small-scale variables, since large-scale errors have larger magnitudes than small-scale ones, and small-scale errors grow faster than large-scale ones. But IHEnKF-Ensemble that updates both the ensemble mean and perturbations with hybrid background error covariances is much less sensitive to scale-dependent inflation, compared to EnSRF and IHEnKF-Mean, because updating ensemble perturbations with hybrid background error covariances can play a role similar to the scale-dependent inflation.

Spin relaxation dynamics with a continuous spin environment: The dissipaton equation of motion approach.

We investigate the quantum dynamics of a spin coupling to a bath of independent spins via the dissipaton equation of motion (DEOM) approach. The bath, characterized by a continuous spectral density function, is composed of spins that are independent level systems described by the su(2) Lie algebra, representing an environment with a large magnitude of anharmonicity. Based on the previous work by Suarez and Silbey [J. Chem. Phys. 95, 9115 (1991)] and by Makri [J. Chem. Phys. 111, 6164 (1999)] that the spin bath can be mapped to a Gaussian environment under its linear response limit, we use the time-domain Prony fitting decomposition scheme to the bare-bath time correlation function (TCF) given by the bosonic fluctuation-dissipation theorem to generate the exponential decay basis (or pseudo modes) for DEOM construction. The accuracy and efficiency of this strategy have been explored by a variety of numerical results. We envision that this work provides new insights into extending the hierarchical equations of motion and DEOM approach to certain types of anharmonic environments with arbitrary TCF or spectral density.

Nonlinear model predictive dynamic positioning of a remotely operated vehicle with wave disturbance preview

Exploiting preview information of disturbances within robot control is an effective method of handling state perturbations. For underwater vehicles operating in wave-dominated environments, disturbances significantly influence vehicle response and pose a threat to operational safety. In consideration of this, a complete end-to-end control architecture is developed in this work for disturbance rejection during station keeping tasks under wave perturbations, encompassing a nonlinear model predictive controller (NMPC) combined with a deterministic sea wave predictor (DSWP). The wave predictor exploits a continuous measurement of the wave elevation at a location upstream of the vehicle to form a forecast of the temporal evolution of the wave elevation at the vehicle location. The predicted wave parameters are then used to estimate the impending wave-induced hydrodynamic loading, enabling explicit consideration of accurate short-term disturbance forecasts within the controller, ensuring this preview is incorporated in the optimised control sequence. Experimental testing confirms the validity of the wave predictor, producing RMSE as low as 0.017 m. The proposed strategy is then simulated under various wave conditions, optimising control actions inclusive of the preview information. The NMPC outperforms a similar disturbance mitigating feed-forward controller, with average improvements of up to 52% and is found to perform best even with noisy, lower accuracy wave predictions, as well as with communication time delays, providing a high degree of robustness. This demonstrates the potential of the proposed control framework to effectively tackle disturbance mitigation of underwater vehicles subject to large magnitude wave disturbances, expanding the operational envelop of autonomous systems towards forbidding ocean environments.

Deconstructing the frame effect.

The perception of an object's location is profoundly influenced by the surrounding dynamics. This is dramatically demonstrated by the frame effect, where a moving frame induces substantial shifts in the perceived location of objects that flash within it. In this study, we examined the elements contributing to the large magnitude of this effect. Across three experiments, we manipulated the number of probes, the dynamics of the frame, and the spatiotemporal relationships between probes and the frame. We found that the presence of multiple probes amplified the position shift, whereas the accumulation of the frame effect over repeated motion cycles was minimal. Notably, an oscillating frame generated more pronounced effects compared to a unidirectional moving frame. Furthermore, the spatiotemporal distance between the frame and the probe played pivotal roles, with larger shifts observed near the leading edge of the frame. Interestingly, although larger frames produced stronger position shifts, the maximum shift occurred almost at the same distance relative to the frame's center across all tested sizes. Our findings suggest that the number of probes, frame size, relative probe-frame distance, and frame dynamics collectively contribute to the magnitude of the position shift.

AT2023vto: An Exceptionally Luminous Helium Tidal Disruption Event from a Massive Star

We present optical/UV observations and the spectroscopic classification of the transient AT2023vto as a tidal disruption event (TDE) at z = 0.4846. The spectrum is dominated by a broad blueshifted He ii λ4686 emission line, classifying it as a member of the TDE-He class. The light curve exhibits a persistent blue color of g − r ≈ −0.4 mag, long rise, and decline timescale, with a large peak absolute magnitude of M g ≈ −23.2, making it the most luminous of the classical optical TDEs (H, H+He, He) discovered to date by about 1.5 mag. We identify the host galaxy of AT2023vto in archival Pan-STARRS images and find that the transient is located at the galaxy center. Modeling the light curves of AT2023vto, we find that it resulted from the disruption of a ≈8 M ⊙ star by a ≈107 M ⊙ supermassive black hole. The star mass is about 5 times larger than the highest star masses previously inferred in TDEs, and the black hole mass is at the high end of the distribution. AT2023vto is comparable in luminosity and timescale to some putative TDEs (blue featureless continuum), as well as to the mean of a recently identified population of ambiguous nuclear transients (ANTs). ANTs have been speculated to arise from tidal disruptions of massive stars, perhaps in active galactic nuclei, and AT2023vto may represent a similar case to ANTs but in a dormant black hole, thereby bridging the TDE and ANT populations. We anticipate that the Rubin Observatory/LSST will uncover similar luminous TDEs to z ∼ 3.

Can we rely on EUV emission to identify coronal waveguides?

Context. Traditional models of coronal oscillations rely on a modelling of the coronal structures that support them as compact cylindrical waveguides. An alternative model of the structure of the corona has recently been proposed, in which the thin strand-like coronal loops, that are observed in the extreme-UV (EUV) emission are the result of the line-of-sight integration of warps in more complex coronal structures. This is referred to as the coronal veil model. Aims. We extend the implications of the coronal veil model of the solar corona to models of coronal oscillations. Methods. Using convection-zone-to-corona simulations with the radiation-magnetohydrodynamics (rMHD) code Bifrost, we analysed the structure of the self-consistently formed simulated corona. We focused on the spatial variability of the volumetric emissivity of the Fe IX 171.073 Å EUV line and on the variability of the Alfvén speed, which captures the density and magnetic structuring of the simulated corona. We traced features associated with large magnitudes of the Alfvén speed gradient, which trap MHD waves and act as coronal waveguides. We searched for the correspondence with emitting regions, which appear as strand-like loops in the line-of-sight-integrated EUV emission. Results. We find that the cross sections of the waveguides bounded by large Alfvén speed gradients become less circular and more distorted with increasing height in the solar atmosphere. The waveguide filling factors corresponding to the fraction of the waveguides filled with plasma that emits in the given EUV wavelength range from 0.09–0.44. This suggests that we can only observe a small fraction of the waveguide. Similarly, the projected waveguide widths in the plane of the sky are several times larger than the widths of the apparent loops that are observed in the EUV. Conclusions. We conclude that the coronal veil structure is independent of the model. As a result, we find a lack of straightforward correspondence between peaks in the integrated emission profile that constitute apparent coronal loops and regions of plasma bound by a large Alfvén speed gradient that act as waveguides. Coronal waveguides cannot be reliably identified based on emission in a single EUV wavelength is not reliable in the simulated corona formed in convection-zone-to-corona models.

Local adaptation can cause both peaks and troughs in nucleotide diversity within populations.

The amount of standing variation present within populations is a fundamental quantity of interest in population genetics, commonly represented by calculating the average number of differences between pairs of nucleotide sequences (nucleotide diversity, π). It is well understood that both background and positive selection can cause reductions in nucleotide diversity, but less clear how local adaptation affects it. Depending on the assumptions and parameters, some theoretical studies have emphasized how local adaptation can reduce nucleotide diversity, while others have shown that it can increase it. Here, we explore how local adaptation shapes genome-wide patterns in within-population nucleotide diversity, extending previous work to study the effects of polygenic adaptation, genotypic redundancy, and population structure. We show that local adaptation produces two very different patterns depending on the relative strengths of migration and selection, either markedly decreasing or increasing within-population diversity at linked sites at equilibrium. At low migration, regions of depleted diversity can extend large distances from the causal locus, with substantially more diversity eroded than expected with background selection. With higher migration, peaks occur over much smaller genomic distances but with much larger magnitude changes in diversity. Across spatially extended environmental gradients, both patterns can be found within a single species, with increases in diversity at the center of the range and decreases towards the periphery. Our results demonstrate that there is no universal diagnostic signature of local adaptation based on within-population nucleotide diversity, so it will not be broadly useful for explaining increased FST. However, given that neither background nor positive selection inflate diversity, when peaks are found they suggest local adaptation may be acting on a causal allele in the region.