Internal Heating of Old Neutron Stars: Contrasting Different Mechanisms

Context: The standard cooling models of neutron stars predict temperatures $T10^{7}$ yr. However, the likely thermal emission detected from the millisecond pulsar J0437-4715, of spin-down age $t_s \sim 7\times10^9$ yr, implies a temperature $T\sim 10^5$ K. Thus, a heating mechanism needs to be added to the cooling models in order to obtain agreement between theory and observation. Aims: Several internal heating mechanisms could be operating in neutron stars, such as magnetic field decay, dark matter accretion, crust cracking, superfluid vortex creep, and non-equilibrium reactions ("rotochemical heating"). We study these mechanisms in order to establish which could be the dominant source of thermal emission from old pulsars. Methods: We show by simple estimates that magnetic field decay, dark matter accretion, and crust cracking mechanism are unlikely to have a significant effect on old neutron stars. The thermal evolution for the other mechanisms is computed using the code of Fern\'andez and Reisenegger. Given the dependence of the heating mechanisms on the spin-down parameters, we study the thermal evolution for two types of pulsars: young, slowly rotating "classical" pulsars and old, fast rotating millisecond pulsars. Results: We find that magnetic field decay, dark matter accretion, and crust cracking do not produce detectable heating of old pulsars. Rotochemical heating and vortex creep can be important both for classical pulsars and millisecond pulsars. More restrictive upper limits on the surface temperatures of classical pulsars could rule out vortex creep as the main source of thermal emission. Rotochemical heating in classical pulsars is driven by the chemical imbalance built up during their early spin-down, and therefore strongly sensitive to their initial rotation period.Comment: 7 pages, 5 figures, accepted version to be published in A&

Sex-specific efficacy and safety of cryoballoon versus radiofrequency ablation for atrial fibrillation: An individual patient data meta-analysis

BACKGROUND: Atrial fibrillation (AF) is a growing health burden, and pulmonary vein isolation (PVI) using cryoballoon (CB) or radiofrequency (RF) represents an attractive therapeutic option. Sex-specific differences in the epidemiology, pathophysiology, and clinical presentation of AF and PVI are recognized. OBJECTIVE: We aimed at comparing the efficacy, safety, and procedural characteristics of CB and RF in women and men undergoing a first PVI procedure. METHODS: We searched for randomized controlled trials and prospective observational studies comparing CB and RF ablation with at least 1 year of follow-up. After merging individual patient data from 18 data sets, we investigated the sex-specific (procedure failure defined as recurrence of atrial arrhythmia, reablation, and reinitiation of antiarrhythmic medication), safety (periprocedural complications), and procedural characteristics of CB vs RF using Kaplan-Meier and multilevel models. RESULTS: From the 18 studies, 4840 men and 1979 women were analyzed. An analysis stratified by sex correcting for several covariates showed a better efficacy of CB in men (hazard ratio for recurrence 0.88; 95% confidence interval 0.78-0.98, P = .02) but not in women (hazard ratio 0.98; 95% confidence interval 0.83-1.16; P = .82). For women and men, the energy source had no influence on the occurrence of at least 1 complication. For both sexes, the procedure time was significantly shorter with CB (-22.5 minutes for women and -27.1 minutes for men). CONCLUSION: CB is associated with less long-term failures in men. A better understanding of AF-causal sex-specific mechanisms and refinements in CB technologies could lead to higher success rates in women

Prognostic Value of H2FPEF Score in COVID-19

Study objective: This study sought to assess the predictive value of H2FPEF score in patients with COVID-19. Design: Retrospective study. Setting: Rush University Medical Center. Participants: A total of 1682 patients had an echocardiogram in the year preceding their COVID-19 admission with a preserved ejection fraction (≥50%). A total of 156 patients met inclusion criteria. Interventions: Patients were divided into H2FPEF into low (0–2), intermediate (3–5), and high (6–9) score H2FPEF groups and outcomes were compared. Main outcome measures: Adjusted multivariable logistic regression models evaluated the association between H2FPEF score group and a composite outcome for severe COVID-19 infection consisting of (1) 60-day mortality or illness requiring (2) intensive care unit, (3) intubation, or (4) non-invasive positive pressure ventilation. Results: High H2FPEF scores were at increased risk for severe COVID-19 infection when compared intermediate to H2FPEF score groups (OR 2.18 [CI: 1.01–4.80]; p = 0.049) and low H2FPEF score groups (OR 2.99 [CI: 1.22–7.61]; p \u3c 0.05). There was no difference in outcome between intermediate H2FPEF scores (OR 1.34 [CI: 0.59–3.16]; p = 0.489) and low H2FPEF score. Conclusions: Patients with a high H2FPEF score were at increased risk for severe COVID-19 infection when compared to patients with an intermediate or low H2FPEF score regardless of regardless of coronary artery disease and chronic kidney disease

Hyperdynamic Left Ventricular Ejection Fraction Is Associated With Higher Mortality in COVID-19 Patients

Study objective: To compare the characteristics and outcomes of COVID-19 patients with a hyperdynamic LVEF (HDLVEF) to those with a normal or reduced LVEF. Design: Retrospective study. Setting: Rush University Medical Center. Participants: Of the 1682 adult patients hospitalized with COVID-19, 419 had a transthoracic echocardiogram (TTE) during admission and met study inclusion criteria. Interventions: Participants were divided into reduced (LVEF \u3c 50%), normal (≥50% and \u3c70%), and hyper- dynamic (≥70%) LVEF groups. Main outcome measures: LVEF was assessed as a predictor of 60-day mortality. Logistic regression was used to adjust for age and BMI. Results: There was no difference in 60-day mortality between patients in the reduced LVEF and normal LVEF groups (adjusted odds ratio [aOR] 0.87, p = 0.68). However, patients with an HDLVEF were more likely to die by 60 days compared to patients in the normal LVEF group (aOR 2.63 [CI: 1.36–5.05]; p \u3c 0.01). The HDLVEF group was also at higher risk for 60-day mortality than the reduced LVEF group (aOR 3.34 [CI: 1.39–8.42]; p \u3c 0.01). Conclusion: The presence of hyperdynamic LVEF during a COVID-19 hospitalization was associated with an increased risk of 60-day mortality, the requirement for mechanical ventilation, vasopressors, and intensive care unit

Dynamical Boson Stars

The idea of stable, localized bundles of energy has strong appeal as a model for particles. In the 1950s John Wheeler envisioned such bundles as smooth configurations of electromagnetic energy that he called {\em geons}, but none were found. Instead, particle-like solutions were found in the late 1960s with the addition of a scalar field, and these were given the name {\em boson stars}. Since then, boson stars find use in a wide variety of models as sources of dark matter, as black hole mimickers, in simple models of binary systems, and as a tool in finding black holes in higher dimensions with only a single killing vector. We discuss important varieties of boson stars, their dynamic properties, and some of their uses, concentrating on recent efforts.Comment: 79 pages, 25 figures, invited review for Living Reviews in Relativity; major revision in 201

Comparison of high-sensitivity cardiac troponin I and T for the prediction of cardiac complications after non-cardiac surgery

We aimed to directly compare preoperative high-sensitivity cardiac troponin (hs-cTn) I and T concentration for the prediction of major cardiac complications after non-cardiac surgery.; We measured hs-cTnI and hs-cTnT preoperatively in a blinded fashion in 1022 patients undergoing non-cardiac surgery. The primary endpoint was a composite of major cardiac complications including cardiac death, cardiac arrest, myocardial infarction, clinically relevant arrhythmias, and acute heart failure within 30 days. We hypothesized that the type of surgery may impact on the predictive accuracy of hs-cTnI/T and stratified all analyses according to the type of surgery.; Major cardiac complications occurred in 108 (11%) patients, 58/243 (24%) patients undergoing vascular surgery and 50/779 (6%, P < .001) patients undergoing non-vascular surgery. Using regulatory-approved 99th percentile cut-off concentrations, preoperative hs-cTnI elevations were less than one-fifth as common as preoperative hs-cTnT elevations (P < .001). Among patients undergoing vascular surgery, preoperative hs-cTnI concentrations, but not hs-cTnT, was an independent predictor of cardiac complications (adjusted odds ratio (aOR) 1.5, 95% confidence interval (95% CI) 1.0-2.1). The area under the receiver-operating characteristics curve (AUC) was 0.67 (95% CI, 0.59-0.75) for hs-cTnI versus 0.59 (95% CI 0.51-0.67, P = .012) for hs-cTnT. In contrast, among patients undergoing non-vascular surgery both preoperative hs-cTnI and hs-cTnT were independent predictors of the primary endpoint (aOR 1.6, 95% CI 1.3-2.0, and aOR 3.0, 95% CI 2.0-4.6, respectively) and showed higher predictive accuracy (AUC 0.77, 95% CI, 0.71-0.83, and 0.79, 95% CI 0.73-0.85, P = ns).; Preoperative hs-cTnI and hs-cTnT concentrations predict major cardiac complications after non-vascular surgery, while, in patients undergoing vascular surgery, hs-cTnI may have better accuracy

Soluble Urokinase Plasminogen Activator Receptor and Venous Thromboembolism in COVID-19

BACKGROUND: Venous thromboembolism (VTE) contributes significantly to COVID-19 morbidity and mortality. The urokinase receptor system is involved in the regulation of coagulation. Levels of soluble urokinase plasminogen activator receptor (suPAR) reflect hyperinflammation and are strongly predictive of outcomes in COVID-19. Whether suPAR levels identify patients with COVID-19 at risk for VTE is unclear. METHODS AND RESULTS: We leveraged a multinational observational study of patients hospitalized for COVID-19 with suPAR and D-dimer levels measured on admission. In 1960 patients (mean age, 58 years; 57% men; 20% Black race), we assessed the association between suPAR and incident VTE (defined as pulmonary embolism or deep vein thrombosis) using logistic regression and Fine-Gray modeling, accounting for the competing risk of death. VTE occurred in 163 (8%) patients and was associated with higher suPAR and D-dimer levels. There was a positive association between suPAR and D-dimer (β=7.34; P=0.002). Adjusted for clinical covariables, including D-dimer, the odds of VTE were 168% higher comparing the third with first suPAR tertiles (adjusted odds ratio, 2.68 [95% CI, 1.51– 4.75]; P<0.001). Findings were consistent when stratified by D-dimer levels and in survival analysis accounting for death as a competing risk. On the basis of predicted probabilities from random forest, a decision tree found the combined D-dimer <1 mg/L and suPAR <11 ng/mL cutoffs, identifying 41% of patients with only 3.6% VTE probability. CONCLUSIONS: Higher suPAR was associated with incident VTE independently of D-dimer in patients hospitalized for COVID-19. Combining suPAR and D-dimer identified patients at low VTE risk. © 2022 The Authors

Reheating neutron stars with the annihilation of self-interacting dark matter

[[abstract]]Compact stellar objects such as neutron stars (NS) are ideal places for capturing dark matter (DM) particles. We study the effect of self-interacting DM (SIDM) captured by nearby NS that can reheat it to an appreciated surface temperature through absorbing the energy released due to DM annihilation. When DM-nucleon cross section σχn is small enough, DM self-interaction will take over the capture process and make the number of captured DM particles increased as well as the DM annihilation rate. The corresponding NS surface temperature resulted from DM self-interaction is about hundreds of Kelvin and is potentially detectable by the future infrared telescopes. Such observations could act as the complementary probe on DM properties to the current DM direct searches.[[notice]]補正完

Soluble Urokinase Plasminogen Activator Receptor and Venous Thromboembolism in COVID‐19

Background Venous thromboembolism (VTE) contributes significantly to COVID‐19 morbidity and mortality. The urokinase receptor system is involved in the regulation of coagulation. Levels of soluble urokinase plasminogen activator receptor (suPAR) reflect hyperinflammation and are strongly predictive of outcomes in COVID‐19. Whether suPAR levels identify patients with COVID‐19 at risk for VTE is unclear. Methods and Results We leveraged a multinational observational study of patients hospitalized for COVID‐19 with suPAR and D‐dimer levels measured on admission. In 1960 patients (mean age, 58 years; 57% men; 20% Black race), we assessed the association between suPAR and incident VTE (defined as pulmonary embolism or deep vein thrombosis) using logistic regression and Fine‐Gray modeling, accounting for the competing risk of death. VTE occurred in 163 (8%) patients and was associated with higher suPAR and D‐dimer levels. There was a positive association between suPAR and D‐dimer (β=7.34; P=0.002). Adjusted for clinical covariables, including D‐dimer, the odds of VTE were 168% higher comparing the third with first suPAR tertiles (adjusted odds ratio, 2.68 [95% CI, 1.51–4.75]; P<0.001). Findings were consistent when stratified by D‐dimer levels and in survival analysis accounting for death as a competing risk. On the basis of predicted probabilities from random forest, a decision tree found the combined D‐dimer <1 mg/L and suPAR <11 ng/mL cutoffs, identifying 41% of patients with only 3.6% VTE probability. Conclusions Higher suPAR was associated with incident VTE independently of D‐dimer in patients hospitalized for COVID‐19. Combining suPAR and D‐dimer identified patients at low VTE risk. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT04818866