Prognostic advantage of optimal medical therapy is not cancelled in hospitalized heart failure patients receiving regular hemodialysis

Background

As the first-line medications, renin-angiotensin-aldosterone system inhibitor (RAASi) and β-blocker provide prognostic benefits in patients with heart failure (HF) and reduced left ventricular ejection fraction (LVEF). However, the negative inotropic effect of these drugs may destabilize the hemodynamics during hemodialysis (HD) and become prognostically controversial in patients receiving regular HD. Indeed, prior studies have reported the cancellation of the favorable prognostic effects of RAASi and β-blocker in patients with HD. However, it is totally unknown whether the guideline-directed medical therapy affects the prognosis in HF patients receiving regular HD.

Purpose

We aimed to evaluate the prognostic impact of RAASi and β-blocker on the cardiovascular (CV) events in HF patients on regular HD.

Methods

This observational study initially included 1,930 consecutive patients who were hospitalized due to HF and discharged alive. Of these, 151 patients who received regular HD were ultimately analyzed. They were classified into 3 groups depending on the prescribing medications at discharge; patients who received none of RAASi or β-blocker (None group: N=19), either RAASi or β-blocker (Either group: N=56), and both RAASi and β-blocker (Both group: N=76). The primary endpoint was a composite of CV death and readmission due to HF.

Results

During the observation period of median 501 (interquartile range: 197–954) days, the primary endpoint occurred in 61 patients (40%). Kaplan-Meier analysis showed the highest rate of composite endpoint in the None group (log-rank for trend: p<0.001, Figure). After adjusting for covariates of age, sex, LVEF, and systolic blood pressure and heart rate at discharge, the hazard ratio (HR) for a composite endpoint was significantly lower in the Either group or Both group than that in the None group [HR: 0.19, 95% confidence interval (CI): 0.08–0.45; HR: 0.16, 95% CI: 0.06–0.42, respectively].

Conclusions

The prescription of RAASi or β-blocker at discharge was associated with lower adverse CV event rates in patients on regular HD who were hospitalized for HF. In order to improve long-term prognosis of HF patients on HD, we should consider the prescription of RAASi or β-blocker for them if hemodynamics during HD is affordable.

Funding Acknowledgement

Type of funding sources: None. Figure 1

Heart failure re-hospitalization differently affects the following mortality in patients with reduced, mid-range and preserved LVEF

Introduction

The recent advances in the treatment for heart failure with reduced ejection fraction (HFrEF) have been remarkable, while no therapy has convincingly improved the prognosis in HF patients with preserved (HFpEF) and mid-range (HFmrEF) ejection fraction. Frequent decompensations of HF lead to progressive deterioration of cardiac and renal function, and quality of life. Hence, prior studies have reported that the mortality of HFrEF patients increases as hospitalization for HF repeats. However, it is still unclear whether this trend applies for HFpEF and HFmrEF patients.

Purpose

We aimed to compare the prognostic impact of re-hospitalization due to HF on cardiovascular death (CVD) among HFrEF, HFmrEF and HFpEF patients.

Methods

This observational study included 1,930 consecutive patients who were hospitalized for worsening of HF and discharged alive. Of them, patients who have never or have not been hospitalized for HF at least last 2 years, were finally analyzed. Patients were consisted of the population with HFrEF (EF<40%, n=421), HFmrEF (EF 40–49%, n=202) and HFpEF (EF>50%, n=291). Patients in each EF-classified population were divide into 2 subgroups based on whether patients were re-hospitalized for HF during the observational period, respectively. The primary endpoint of this study was CVD.

Results

During the observation period, Kaplan-Meier analysis showed that patients who were re-hospitalized for HF had higher event rate of CVD in HFrEF group (Log-rank p=0.008, Figure). Even after adjusting with multivariate covariates including age, sex, EF, brain natriuretic peptide and estimated glomerular filtration rate, re-hospitalization for HF was an independent predictor for CVD in HFrEF group (HR: 1.95, 95% CI: 1.11–2.86, p=0.029). However, in HFmrEF group and HFpEF group, there was no significant difference in the rates of CVD between 2 subgroups divided whether patients were re-hospitalized for HF or not (p=0.91, p=0.34, respectively).

Conclusion

Re-hospitalization for HF affected the CVD rate in HFrEF group, but not in HFmrEF and HFpEF groups. The prevention of re-hospitalization for HF is important particularly in HFrEF patients in order to improve cardiovascular mortality.

Funding Acknowledgement

Type of funding sources: None.

Influence of renal dysfunction on clinical outcomes in elderly patients with atrial fibrillation: a subanalysis of the phase 3, randomized, placebo-controlled ELDERCARE-AF trial

Background

Renal dysfunction is common in elderly patients with atrial fibrillation (AF) and is thought to be associated with increased risk of thromboembolic and bleeding events. Once-daily low-dose (15 mg) edoxaban was superior to placebo in preventing stroke or systemic embolic events (S/SEE) without significantly increasing major bleeding events in very elderly (≥80 years) non-valvular AF (NVAF) patients in whom standard oral anticoagulant therapy at approved doses was inappropriate (ELDERCARE-AF trial). Little is known about how renal dysfunction affects the effects of low-dose edoxaban in these patients.

Purpose

We used prespecified subgroup analysis to investigate the relation between renal function (assessed by creatinine clearance, CrCl) and the efficacy and safety of edoxaban in elderly NVAF patients.

Methods

ELDERCARE-AF patients were divided into 3 subgroups according to baseline CrCl: normal renal function/mild dysfunction (CrCl >50 mL/min), moderate renal dysfunction (CrCl ≥30 to ≤50 [“30–50”] mL/min) and severe renal dysfunction (CrCl ≥15 to <30 [“15–30”] mL/min). Primary efficacy and safety endpoints were annualized incidence of S/SEE and ISTH-defined major bleeding, respectively.

Results

Of 984 patients randomized to edoxaban 15 mg or placebo (each group N=492), 681 completed the trial. The 303 discontinuations were due to withdrawal of consent (n=158), death (n=135), or other causes (n=10). Discontinuation rate was the same in the edoxaban and placebo groups. S/SEE incidence in patients with CrCl >50, 30–50 and 15–30 mL/min was 2.0%, 1.3% and 3.5%, respectively, in edoxaban, and 4.4%, 4.6% and 9.7%, respectively, in placebo. In those with CrCl 30–50 and 15–30 mL/min, it was significantly lower in edoxaban than in placebo (adjusted hazard ratio [HR], 0.30 [95% CI, 0.10–0.91], p=0.03; and 0.33 [95% CI, 0.16–0.71], p<0.01, respectively). Incidence of major bleeding in patients with CrCl >50, 30–50 and 15–30 mL/min was 1.0%, 1.8% and 6.2%, respectively, in edoxaban, and 0.9%, 1.5% and 2.4%, respectively, in placebo. Incidence of major bleeding in those with CrCl 15–30 mL/min was higher in edoxaban but not significantly (adjusted HR, 2.53 [95% CI, 0.96–6.72], p=0.062). Incidence of gastrointestinal bleeding in patients with CrCl 15–30 mL/min was 4.3% in edoxaban and 1.6% in placebo (adjusted HR, 2.61 [95% CI, 0.79–8.68], p=0.12). Incidence of all-cause death in patients with CrCl >50, 30–50 and 15–30 mL/min was 5.8%, 6.8% and 15.2%, respectively, in edoxaban, and 7.0%, 6.3% and 15.5%, respectively, in placebo (no significant intergroup differences).

Conclusions

Incidence of S/SEE, major bleeding and all-cause death increased with declining renal function in elderly NVAF patients. Edoxaban 15 mg remained superior to placebo in preventing S/SEE, even in those with moderate to severe renal dysfunction. Incidence of major bleeding in patients with severe renal dysfunction was higher (non-significantly) with edoxaban than with placebo.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): Daiichi-Sankyo Co., Ltd.

Gastric epithelial neoplasm of fundic-gland mucosa lineage: proposal for a new classification in association with gastric adenocarcinoma of fundic-gland type

BACKGROUND

Gastric adenocarcinoma of fundic-gland type (GA-FG) is a rare variant of gastric neoplasia. However, the etiology, classification, and clinicopathological features of gastric epithelial neoplasm of fundic-gland mucosa lineage (GEN-FGML; generic term of GA-FG related neoplasm) are not fully elucidated. We performed a large, multicenter, retrospective study to establish a new classification and clarify the clinicopathological features of GEN-FGML.

METHODS

One hundred GEN-FGML lesions in 94 patients were collected from 35 institutions between 2008 and 2019. We designed a new histopathological classification of GEN-FGML using immunohistochemical analysis and analyzed via clinicopathological, immunohistochemical, and genetic evaluation.

RESULTS

GEN-FGML was classified into 3 major types; oxyntic gland adenoma (OGA), GA-FG, and gastric adenocarcinoma of fundic-gland mucosa type (GA-FGM). In addition, GA-FGM was classified into 3 subtypes; Type 1 (organized with exposure type), Type 2 (disorganized with exposure type), and Type 3 (disorganized with non-exposure type). OGA and GA-FG demonstrated low-grade epithelial neoplasm, and GA-FGM should be categorized as an aggressive variant of GEN-FGML that demonstrated high-grade epithelial neoplasm (Type 2 > 1, 3). The frequent presence of GNAS mutation was a characteristic genetic feature of GEN-FGML (7/34, 20.6%; OGA 1/3, 33.3%; GA-FG 3/24, 12.5%; GA-FGM 3/7, 42.9%) in mutation analysis using next-generation sequencing.

CONCLUSIONS

We have established a new histopathological classification of GEN-FGML and propose a new lineage of gastric epithelial neoplasm that harbors recurrent GNAS mutation. This classification will be useful to estimate the malignant potential of GEN-FGML and establish an appropriate standard therapeutic approach.

P–131 Significance of the phenomenon of blastomere exclusion from compaction: Its relation to irregular cleavage, blastocyst development rate, and pregnancy rate

Study question

When does blastomere exclusion from compaction increase and what effect does it have on the embryo?

Summary answer

More blastomere were excluded from compaction in embryos with irregular cleavage, resulting in lower blastocyst development rates, but no decrease in pregnancy rates at transfer.

What is known already

It has been reported that many of the chromosome analysis results of blastomere excluded from compaction were aneuploid, and pointed out that this exclusion may be related to the repair of blastocyst euploidy, but the effect of the number of excluded blastomere has not been reported.

Study design, size, duration

This is a retrospective study of 578 embryos that developed into morula with time-lapse monitoring by EmbryoScope (Vitrolife) in 2018–2019.

Participants/materials, setting, methods

The target embryos were classified into two groups: embryos with normal first and second cleavage (normal cleavage group) and embryos with irregular cleavage (dynamics of one cell dividing into three or more cells), called “direct cleavage”, at either cleavage (DC group), and the number of blastomere excluded from compaction during morula formation was recorded and compared. The blastocyst development rate and single blastocyst transfer pregnancy rates of the two groups were compared.

Main results and the role of chance

There are 286 in the normal cleavage group and 292 in the DC group. The mean number of excluded blastomere was 0.76 and 3.55, respectively, which was significantly higher in the DC group (P < 0.01). Good blastocyst (Gardner classification 4 or higher) development rate was 84.5% (239/283) and 65.8% (181/275), respectively, and high grade blastocyst (Gardner classification BB or higher) development rate was 43.9% (105/239) and 14.9% (27/181) of them, both significantly higher in the normal cleavage group (P < 0.01). The single blastocyst transfer pregnancy rates were 31.6% (25/79) and 32.4% (11/34), and the miscarriage rates were 24.0% (6/25) and 27.3% (3/11), respectively, neither was there a significant difference between the two groups. So, direct cleavage increased the number of blastomere excluded from compaction, decreased the rate of morula to good blastocyst development and reduced blastocyst grade, but did not affect blastocyst transfer pregnancy rate and miscarriage rate.

Limitations, reasons for caution

Please note that all target embryos must have developed into morula or larger (embryos that did not develop into morula will not be included in the study).

Wider implications of the findings: Severe chromosomal aberrant blastomeres formed by direct cleavage were excluded from compaction, and the blastocyst development rate decreased due to a decrease in the amount of viable cells, but it is suggested that this blastomere exclusion mechanism is not related to euploidy after blastocyst development.

Trial registration number

Not applicable

Deexcitation Dynamics of Muonic Atoms Revealed by High-Precision Spectroscopy of Electronic K X Rays

We observed electronic K x rays emitted from muonic iron atoms using superconducting transition-edge sensor microcalorimeters. The energy resolution of 5.2 eV in FWHM allowed us to observe the asymmetric broad profile of the electronic characteristic Kα and Kβ x rays together with the hypersatellite K^{h}α x rays around 6 keV. This signature reflects the time-dependent screening of the nuclear charge by the negative muon and the L-shell electrons, accompanied by electron side feeding. Assisted by a simulation, these data clearly reveal the electronic K- and L-shell hole production and their temporal evolution on the 10-20 fs scale during the muon cascade process.

Evidence-based clinical practice guidelines for peptic ulcer disease 2020

The Japanese Society of Gastroenterology (JSGE) revised the third edition of evidence-based clinical practice guidelines for peptic ulcer disease in 2020 and created an English version. The revised guidelines consist of nine items: epidemiology, hemorrhagic gastric and duodenal ulcers, Helicobacter pylori (H. pylori) eradication therapy, non-eradication therapy, drug-induced ulcers, non-H. pylori, and nonsteroidal anti-inflammatory drug (NSAID) ulcers, remnant gastric ulcers, surgical treatment, and conservative therapy for perforation and stenosis. Therapeutic algorithms for the treatment of peptic ulcers differ based on ulcer complications. In patients with NSAID-induced ulcers, NSAIDs are discontinued and anti-ulcer therapy is administered. If NSAIDs cannot be discontinued, the ulcer is treated with proton pump inhibitors (PPIs). Vonoprazan (VPZ) with antibiotics is recommended as the first-line treatment for H. pylori eradication, and PPIs or VPZ with antibiotics is recommended as a second-line therapy. Patients who do not use NSAIDs and are H. pylori negative are considered to have idiopathic peptic ulcers. Algorithms for the prevention of NSAID- and low-dose aspirin (LDA)-related ulcers are presented in this guideline. These algorithms differ based on the concomitant use of LDA or NSAIDs and ulcer history or hemorrhagic ulcer history. In patients with a history of ulcers receiving NSAID therapy, PPIs with or without celecoxib are recommended and the administration of VPZ is suggested for the prevention of ulcer recurrence. In patients with a history of ulcers receiving LDA therapy, PPIs or VPZ are recommended and the administration of a histamine 2-receptor antagonist is suggested for the prevention of ulcer recurrence.

Hepatocellular carcinoma development in diabetic patients: a nationwide survey in Japan

BACKGROUND

Although type 2 diabetes mellitus (T2DM) is a known risk factor for hepatocellular carcinoma (HCC) development, the annual incidence in diabetes patients is far below the threshold of efficient surveillance. This study aimed to elucidate the risk factors for HCC in diabetic patients and to determine the best criteria to identify surveillance candidates.

METHODS

The study included 239 patients with T2DM who were diagnosed with non-viral HCC between 2010 and 2015, with ≥ 5 years of follow-up at diabetes clinics of 81 teaching hospitals in Japan before HCC diagnosis, and 3277 non-HCC T2DM patients from a prospective cohort study, as controls. Clinical data at the time of and 5 years before HCC diagnosis were collected.

RESULTS

The mean patient age at HCC diagnosis was approximately 73 years, and 80% of the patients were male. The proportion of patients with insulin use increased, whereas the body mass index (BMI), proportion of patients with fatty liver, fasting glucose levels, and hemoglobin A1c (HbA1c) levels decreased significantly in 5 years. In the cohort study, 18 patients developed HCC during the mean follow-up period of 4.7 years with an annual incidence of 0.11%. Multivariate logistic regression analyses showed that the FIB-4 index was an outstanding predictor of HCC development along with male sex, presence of hypertension, lower HbA1c and albumin levels, and higher BMI and gamma-glutamyl transpeptidase levels. Receiver-operating characteristic analyses showed that a FIB-4 cut-off value of 3.61 could help identify high-risk patients, with a corresponding annual HCC incidence rate of 1.1%.

CONCLUSION

A simple calculation of the FIB-4 index in diabetes clinics can be the first step toward surveillance of HCC with a non-viral etiology.

Strongly correlated superconductivity in a copper-based metal-organic framework with a perfect kagome lattice

Metal-organic frameworks (MOFs), which are self-assemblies of metal ions and organic ligands, provide a tunable platform to search a new state of matter. A two-dimensional (2D) perfect kagome lattice, whose geometrical frustration is a key to realizing quantum spin liquids, has been formed in the π - d conjugated 2D MOF [Cu₃(C₆S₆)] _n (Cu-BHT). The recent discovery of its superconductivity with a critical temperature T _c of 0.25 kelvin raises fundamental questions about the nature of electron pairing. Here, we show that Cu-BHT is a strongly correlated unconventional superconductor with extremely low superfluid density. A nonexponential temperature dependence of superfluid density is observed, indicating the possible presence of superconducting gap nodes. The magnitude of superfluid density is much smaller than those in conventional superconductors and follows the Uemura's relation of strongly correlated superconductors. These results imply that the unconventional superconductivity in Cu-BHT originates from electron correlations related to spin fluctuations of kagome lattice.

The utility of a novel approach to quantify dyssynchrony by multidetector computed tomography

Funding Acknowledgements

Type of funding sources: None.

Background

Quantification of left ventricular (LV) dyssynchrony is of great interest for resynchronization therapy (CRT). Recently, cardiac computed tomography (CCT) is feasible for evaluation of dyssynchrony. Our aim was to assess a novel simplified approach using CCT to quantify LV dyssynchrony.

Methods

We studied 346 consecutive patients with a wide range of QRS width and ejection fractions (EF). Electrocardiogram-gated contrast-enhanced 256-slice multidetector CT (Brilliance 256 iCT, Philips Medical Systems) was performed before CRT. After CCT scan, the LV endocardial boundaries from short-axis images reconstructed at 5% increments of cardiac cycle were automatically detected, and a time from R-wave to maximal wall motion was calculated for each of the 16 standardized segments for all slices using software "Myocardial Contraction Map" (Argus, Inc Ehime, Japan). The standard deviation of all segments modified by mean heart rate (%SD) was respectively calculated as the global parameter of dyssynchrony. LVEF was also measured using MDCT.

Results

%SD was feasible in all patients, respectably. %SD was significantly different between the different QRS duration groups; narrow QRS (<120ms): 9 ± 5%, relatively wide QRS (120-150 ms): 11 ± 6%, and significantly wide QRS (>150 ms): 14 ± 7% (p <0.001). Moreover, there was significantly difference in %SD between the different morphology groups; normal: 9 ± 7%, Non-left bundle branch block (Non-LBBB): 10 ± 6%, LBBB: 17 ± 7% (p <0.001).

Conclusion

This novel simplified approach by CCT can quantify dyssynchrony in different QRS duration and morphology groups. This method has promise for clinical applications to the evaluation of patients for CRT.

Abstract Figure.

A case of neonate effectively treated with everolimus for giant hepatic hemangioma complicated with congenital duodenal atresia and Kasabach-Merritt syndrome

BACKGROUND

Disseminated intravascular coagulation (DIC) with Kasabach-Merrit syndrome from a large hepatic hemangioma is life-threatening. We report a case of giant hepatic hemangioma of the newborn with KMS.

RESULTS

The patient was born at 37 gestational weeks and 2 days via cesarean section; weight at birth was 2952 g. Congenital duodenal atresia was noted during the fetal period. DIC developed after delivery and a giant liver hemangioma was diagnosed via abdominal CT. The cause of DIC was Kasabach-Merritt syndrome owing to a giant hepatic hemangioma. First, combination therapy of 2 mg/kg/day of prednisolone and 0.2 mg/kg/day of propranolol was initiated form enterostomy. However, the size of the hepatic hemangioma did not alter, as observed via image evaluation. Therefore, 0.3 mg/kg/day of everolimus was administered frorm enterostomy. Subsequently, the size of the hepatic hemangioma was assessed via image evaluation. Although it did not alter, blood flow to the hepatic hemangioma decreased and thrombocytopenia was also suppressed. We performed hepatic lateral segmentectomy, radical operation for duodenal atresia. The pathological diagnosis of the removed tumor was infantile hemangioma.

CONCLUSION

We report everolimus may be useful when PSL and propranolol are ineffective.

Brightness modulations of our nearest terrestrial planet Venus reveal atmospheric super-rotation rather than surface features

Terrestrial exoplanets orbiting within or near their host stars’ habitable zone are potentially apt for life. It has been proposed that time-series measurements of reflected starlight from such planets will reveal their rotational period, main surface features and some atmospheric information. From imagery obtained with the Akatsuki spacecraft, here we show that Venus’ brightness at 283, 365, and 2020 nm is modulated by one or both of two periods of 3.7 and 4.6 days, and typical amplitudes  <10% but occasional events of 20–40%. The modulations are unrelated to the solid-body rotation; they are caused by planetary-scale waves superimposed on the super-rotating winds. Here we propose that two modulation periods whose ratio of large-to-small values is not an integer number imply the existence of an atmosphere if detected at an exoplanet, but it remains ambiguous whether the atmosphere is optically thin or thick, as for Earth or Venus respectively. Multi-wavelength and long temporal baseline observations may be required to decide between these scenarios. Ultimately, Venus represents a false positive for interpretations of brightness modulations of terrestrial exoplanets in terms of surface features.

Establishing diagnostics for terrestrial exoplanets are crucial for their characterization. Here, the authors show brightness modulations of Venus are caused by planetary-scale waves superimposed on the super-rotating winds can be used to detect existence of an atmosphere if detected at an exoplanet.

Quantitative analysis of dyssynchrony assessed by multidetector computed tomography can predict clinical outcome after cardiac resynchronization therapy

Background

The degree of mechanical dyssynchrony has been suggested as a predictor for long-term survival after cardiac resynchronization therapy (CRT). There have been little reports of dyssynchrony assessment with the use of cardiac computed tomography (CCT).

Methods

We studied 35 heart failure (HF) patients (average age 67±10 years) referred for CRT with NYHA III-IV heart failure, left ventricular (LV) ejection fraction (EF) 20±10% (all ≤35%), and QRS duration 156±22 ms (all ≥120ms). Electrocardiogram-gated contrast-enhanced 256-slice multidetector CT was performed before CRT. Based on CCT, the LV endocardial boundaries from short-axis images reconstructed at 5% increments of cardiac cycle were automatically detected, and the time from R-wave to maximal wall motion was calculated for each of the 16 standardized segments for all slices using software “Myocardial Contraction Map”. The standard deviation modified by mean heart rate (%SD) was respectively calculated as the global parameter of dyssynchrony. LVEF was also measured using MDCT. The predefined primary end-point was the first HF hospitalization or death over 2 years.

Results

%SD was feasible in all patients, respectably. There were 16 events over 2 years; 11 HF hospitalizations and 5 deaths. Patients with %SD ≥22% (optimal cutoff for outcome by ROC curve analysis) had a better clinical outcome than patients with %SD &lt;22% (p=0.01, Figure).

Conclusion

Patients who had %SD ≥22% assessed by MDCT had a particularly favorable event-free survival following CRT, and this appears to be an important prognostic marker.

Funding Acknowledgement

Type of funding source: None

Magnon Modes of Microstates and Microwave-Induced Avalanche in Kagome Artificial Spin Ice with Topological Defects

We investigate spin dynamics of microstates in artificial spin ice (ASI) in Ni_{81}Fe_{19} nanomagnets arranged in an interconnected kagome lattice using microfocus Brillouin light scattering, broadband ferromagnetic resonance, magnetic force microscopy, x-ray photoemission electron microscopy, and simulations. We experimentally reconfigure microstates in ASI using a 2D vector field protocol and apply microwave-assisted switching to intentionally trigger reversal. Our work is key for the creation of avalanches inside the kagome ASI and reprogrammable magnonics based on ASIs.

Daytime Dynamo Electrodynamics With Spiral Currents Driven by Strong Winds Revealed by Vapor Trails and Sounding Rocket Probes

We investigate the forces and atmosphere-ionosphere coupling that create atmospheric dynamo currents using two rockets launched nearly simultaneously on 4 July 2013 from Wallops Island (USA), during daytime Sq conditions with ΔH of -30 nT. One rocket released a vapor trail observed from an airplane which showed peak velocities of >160 m/s near 108 km and turbulence coincident with strong unstable shear. Electric and magnetic fields and plasma density were measured on a second rocket. The current density peaked near 110 km exhibiting a spiral pattern with altitude that mirrored that of the winds, suggesting the dynamo is driven by tidal forcing. Such stratified currents are obscured in integrated ground measurements. Large electric fields produced a current opposite to that driven by the wind, believed created to minimize the current divergence. Using the observations, we solve the dynamo equation versus altitude, providing a new perspective on the complex nature of the atmospheric dynamo.

Collisional formation of top-shaped asteroids and implications for the origins of Ryugu and Bennu

Asteroid shapes and hydration levels can serve as tracers of their history and origin. For instance, the asteroids (162173) Ryugu and (101955) Bennu have an oblate spheroidal shape with a pronounced equator, but contain different surface hydration levels. Here we show, through numerical simulations of large asteroid disruptions, that oblate spheroids, some of which have a pronounced equator defining a spinning top shape, can form directly through gravitational reaccumulation. We further show that rubble piles formed in a single disruption can have similar porosities but variable degrees of hydration. The direct formation of top shapes from single disruption alone can explain the relatively old crater-retention ages of the equatorial features of Ryugu and Bennu. Two separate parent-body disruptions are not necessarily required to explain their different hydration levels.