Spacelike Singularities and Hidden Symmetries of Gravity

We review the intimate connection between (super-)gravity close to a spacelike singularity (the "BKL-limit") and the theory of Lorentzian Kac-Moody algebras. We show that in this limit the gravitational theory can be reformulated in terms of billiard motion in a region of hyperbolic space, revealing that the dynamics is completely determined by a (possibly infinite) sequence of reflections, which are elements of a Lorentzian Coxeter group. Such Coxeter groups are the Weyl groups of infinite-dimensional Kac-Moody algebras, suggesting that these algebras yield symmetries of gravitational theories. Our presentation is aimed to be a self-contained and comprehensive treatment of the subject, with all the relevant mathematical background material introduced and explained in detail. We also review attempts at making the infinite-dimensional symmetries manifest, through the construction of a geodesic sigma model based on a Lorentzian Kac-Moody algebra. An explicit example is provided for the case of the hyperbolic algebra E10, which is conjectured to be an underlying symmetry of M-theory. Illustrations of this conjecture are also discussed in the context of cosmological solutions to eleven-dimensional supergravity.Comment: 228 pages. Typos corrected. References added. Subject index added. Published versio

Body composition markers are associated with changes in inflammatory markers but not vice versa: A bi-directional longitudinal analysis in a population-based sample

Background and aim Growing body of evidence consistently link obesity and inflammation, Although the direction of the association is still unclear. We aimed to investigate longitudinal associations of body anthropometric, composition and fat distribution parameters with inflammatory markers and vice versa. Method and results We used data from 2464 individuals of the SHIP-TREND cohort with a median follow-up of 7 years. Linear regression models adjusted for confounders were used to analyze associations of standardized body composition markers derived from classic anthropometry, bioelectrical impedance analysis (BIA) and magnetic resonance imaging (MRI) at baseline with changes in inflammatory markers (C-reactive protein (CRP), white blood cell (WBC), fibrinogen) and vice versa. Higher level of anthropometric markers at baseline were associated with an increase in the change of inflammatory markers. A 13.5 cm higher waist circumference (WC), 16.0 kg body weight and 7.76 % relative fat mass (FM) at baseline was associated with a change in CRP of 0.52 mg/L (95 % confidence interval [CI]: 0.29 to 0.74), 0.51 mg/L (95 % CI: 0.29; 0.74) and 0.58 mg/L (95 % CI: 0.34; 0.82) respectively. Absolute FM showed the strongest association with changes in serum fibrinogen levels (β for 8.69 kg higher FM: 0.07 g/L; 95 % CI: 0.05; 0.09). Baseline inflammatory markers were only associated with changes in hip circumference. Conclusion Our study indicates the importance of anthropometric, body composition and fat distribution markers as a risk factor for the development of inflammation. To prevent inflammatory-related complications, important is to take measures against the development of obesity

Body surface scan anthropometrics are associated with grip strength in the general population

Background and aim Body shape and anthropometrics are well-known risk factors for cardiovascular diseases (CVD) and mortality. Hand-grip strength (HGS) is also a meaningful marker of health and a promising predictor of CVD and mortality. There is a lack of studies that have systematically investigated associations between body shape and anthropometrics with HGS. In a population-based study, we investigated if anthropometric markers derived from 3D body scanning are related to HGS. Methods and results We used the data of 1,599 individuals aged 36 to 93 years, who participated in the Study of Health in Pomerania. A total of 87 anthropometric markers, determined by a 3D body scanner, were included in the analysis. Anthropometric measurements were standardized and used as exposure variables. HGS was measured with a hand dynamometer and used as outcome. Sex-stratified linear regression models adjusted for age and height were used to relate standardized anthropometrics and HGS. Anthropometric markers were ranked according to -log-p-values. In men, left and right forearm circumference, left arm length to neck (C7), left forearm length, and forearm-fingertip length were most strongly related to HGS. In women, right forearm circumference, forearm-fingertip length, shoulder breadth, left forearm circumference, and right wrist circumference showed the most significant associations with HGS. The final prediction models contained 13 anthropometric markers in males (R2=0.54) and eight anthropometric markers in females (R2=0.37). Conclusions The identified parameters may help estimate HGS in the clinical setting. However, studies in clinical settings are essential to validating our findings

The Association Between C24:0/C16:0 Ceramide Ratio and Cardiorespiratory Fitness is Robust to Effect Modifications by Age and Sex

Ceramides and cardiorespiratory (CR) fitness are both related to cardiovascular diseases. The associations of three blood plasma ceramides (C16:0, C22:0, and C24:0) with CR fitness in the population‐based Study of Health in Pomerania (SHIP‐START‐1; n = 1,102; mean age 50.3 years, 51.5% women) are investigated. In addition, subgroup analysis according to age (</≥54 years) and sex (female/male) is performed. Ceramides are quantified by liquid chromatography/mass spectrometry (LC/MS). CR fitness is assessed by a cardiopulmonary exercise test. Sex and age independent associations are found for higher levels of C24:0 and C24:0/C16:0 ratio with higher maximal oxygen consumption (VO2peak) kg−1 and oxygen consumption at the anaerobic threshold (VO2@AT1) as well as for the relation of C24:0/C16:0 with maximum workload (Wattmax kg−1). In contrast, age/sex subgroup specific inverse associations with Wattmax kg−1 are found in women <54 years for C22:0, while a positive association in men ≥54 years. Higher levels of C24:0 are associated with higher Wattmax kg−1, except for women <54 years, where no significant association can be found. The findings suggest that the use of single ceramides as cardiovascular biomarkers may be inferior, compared to ceramide ratio C24:0/C16:0. Therefore C24:0/C16:0 ratio may be a more suitable and robust cardiovascular biomarker and should be preferred over single ceramides

Low-Circulating Homoarginine is Associated with Dilatation and Decreased Function of the Left Ventricle in the General Population

Low homoarginine is an independent marker of mortality in heart failure patients and incident cardiovascular events. Whether homoarginine is related with healthier cardiac structure and function is currently unclear. We used data of the population-based Study of Health in Pomerania (SHIP-Trend) to assess this relation. Homoarginine was measured in serum using liquid chromatography-tandem mass spectrometry. Linear regression models assessed the relation between homoarginine and several structural as well as functional parameters and N-terminal pro B-type natriuretic peptide (NTproBNP). All models were adjusted for age, sex, body mass index, and renal function. A total of 3113 subjects (median age 48 (25th percentile 37 to 75th percentile 60) years, 46% male) were included. A standard deviation decrease in homoarginine was associated with a larger left ventricular diastolic diameter (0.3;95%-confidence interval (CI): 0.2 to 0.5 mm;p < 0.001), left ventricular systolic diameter (0.38;95%-CI: -0.22 to 0.54 mm;p < 0.001) as well as a less relative wall thickness (-0.003 95%-CI: -0.006 to -0.0008;p = 0.01), left ventricular ejection fraction (-0.47;95%-CI: -0.79 to -0.15%;p < 0.01) and fractional shortening (-0.35;95%-CI: -0.62 to 0.07%;p = 0.01). Low homoarginine was also related to higher NTproBNP (-0.02 95%-CI: -0.034 to -0.009 log pg/mL;p < 0.01). Lower serum homoarginine is associated with dilatation of the heart and decreased function. Prospective clinical studies should assess if homoarginine supplementation improves cardiac health in subjects with low serum concentrations

Progression of conventional cardiovascular risk factors and vascular disease risk in individuals: insights from the PROG-IMT consortium

Aims Averaged measurements, but not the progression based on multiple assessments of carotid intima-media thickness, (cIMT) are predictive of cardiovascular disease (CVD) events in individuals. Whether this is true for conventional risk factors is unclear. Methods and results An individual participant meta-analysis was used to associate the annualised progression of systolic blood pressure, total cholesterol, low-density lipoprotein cholesterol and high-density lipoprotein cholesterol with future cardiovascular disease risk in 13 prospective cohort studies of the PROG-IMT collaboration (n = 34,072). Follow-up data included information on a combined cardiovascular disease endpoint of myocardial infarction, stroke, or vascular death. In secondary analyses, annualised progression was replaced with average. Log hazard ratios per standard deviation difference were pooled across studies by a random effects meta-analysis. In primary analysis, the annualised progression of total cholesterol was marginally related to a higher cardiovascular disease risk (hazard ratio (HR) 1.04, 95% confidence interval (CI) 1.00 to 1.07). The annualised progression of systolic blood pressure, low-density lipoprotein cholesterol and high-density lipoprotein cholesterol was not associated with future cardiovascular disease risk. In secondary analysis, average systolic blood pressure (HR 1.20 95% CI 1.11 to 1.29) and low-density lipoprotein cholesterol (HR 1.09, 95% CI 1.02 to 1.16) were related to a greater, while high-density lipoprotein cholesterol (HR 0.92, 95% CI 0.88 to 0.97) was related to a lower risk of future cardiovascular disease events. Conclusion Averaged measurements of systolic blood pressure, low-density lipoprotein cholesterol and high-density lipoprotein cholesterol displayed significant linear relationships with the risk of future cardiovascular disease events. However, there was no clear association between the annualised progression of these conventional risk factors in individuals with the risk of future clinical endpoints

Corrigendum to “Should workers be physically active after work? Associations of leisure-time physical activity with cardiovascular and all-cause mortality across occupational physical activity levels—An individual participant data meta-analysis” (J Sport Health Sci 14 [2025] 100987) (Journal of Sport and Health Science (2025) 14, (S2095254624001431), (10.1016/j.jshs.2024.100987))

This is a corrigendum to the published paper entitled “Should workers be physically active after work? Associations of leisure-time physical activity with cardiovascular and all-cause mortality across occupational physical activity levels–An individual participant data meta-analysis”.1 In Table 1 (Page 5) and Supplementary Material 1, the citation for the HUNT Study data was incorrectly attributed to “Moe et al.”. After further review, we have corrected this error by replacing “Moe et al.” with the correct citation “Krokstad et al.” in the revised Table 1 (revisions shown in red). We can further confirm that this error in citation does not affect the statistical analyses or the data interpretation presented in the paper. The correction pertains solely to the proper citation of the HUNT Study data.</p

Should workers be physically active after work? Associations of leisure-time physical activity with cardiovascular and all-cause mortality across occupational physical activity levels

Background: There is insufficient evidence to provide recommendations for leisure-time physical activity among workers across various occupational physical activity levels. This study aimed to assess the association of leisure-time physical activity with cardiovascular and all-cause mortality across occupational physical activity levels. Methods: This study utilized individual participant data from 21 cohort studies, comprising both published and unpublished data. Eligibility criteria included individual-level data on leisure-time and occupational physical activity (categorized as sedentary, low, moderate, and high) along with data on all-cause and/or cardiovascular mortality. A 2-stage individual participant data meta-analysis was conducted, with separate analysis of each study using Cox proportional hazards models (Stage 1). These results were combined using random-effects models (Stage 2). Results: Higher leisure-time physical activity levels were associated with lower all-cause and cardiovascular mortality risk across most occupational physical activity levels, for both males and females. Among males with sedentary work, high compared to sedentary leisure-time physical activity was associated with lower all-cause (hazard ratios (HR) = 0.77, 95% confidence interval (95%CI): 0.70-0.85) and cardiovascular mortality (HR = 0.76, 95%CI: 0.66-0.87) risk. Among males with high levels of occupational physical activity, high compared to sedentary leisure-time physical activity was associated with lower all-cause (HR = 0.84, 95%CI: 0.74-0.97) and cardiovascular mortality (HR = 0.79, 95%CI: 0.60-1.04) risk, while HRs for low and moderate levels of leisure-time physical activity ranged between 0.87 and 0.97 and were not statistically significant. Among females, most effects were similar but more imprecise, especially in the higher occupational physical activity levels. Conclusion: Higher levels of leisure-time physical activity were generally associated with lower mortality risks. However, results for workers with moderate and high occupational physical activity levels, especially women, were more imprecise. Our findings suggests that workers may benefit from engaging in high levels of leisure-time physical activity, irrespective of their level of occupational physical activity