Constraining warm dark matter with cosmic shear power spectra

We investigate potential constraints from cosmic shear on the dark matter particle mass, assuming all dark matter is made up of light thermal relic particles. Given the theoretical uncertainties involved in making cosmological predictions in such warm dark matter scenarios we use analytical fits to linear warm dark matter power spectra and compare (i) the halo model using a mass function evaluated from these linear power spectra and (ii) an analytical fit to the non-linear evolution of the linear power spectra. We optimistically ignore the competing effect of baryons for this work. We find approach (ii) to be conservative compared to approach (i). We evaluate cosmological constraints using these methods, marginalising over four other cosmological parameters. Using the more conservative method we find that a Euclid-like weak lensing survey together with constraints from the Planck cosmic microwave background mission primary anisotropies could achieve a lower limit on the particle mass of 2.5 keV.Comment: 26 pages, 9 figures, minor changes to match the version accepted for publication in JCA

Non-minimally coupled dark matter: effective pressure and structure formation

We propose a phenomenological model in which a non-minimal coupling between gravity and dark matter is present in order to address some of the apparent small scales issues of \lcdm model. When described in a frame in which gravity dynamics is given by the standard Einstein-Hilbert action, the non-minimal coupling translates into an effective pressure for the dark matter component. We consider some phenomenological examples and describe both background and linear perturbations. We show that the presence of an effective pressure may lead these scenarios to differ from \lcdm at the scales where the non-minimal coupling (and therefore the pressure) is active. In particular two effects are present: a pressure term for the dark matter component that is able to reduce the growth of structures at galactic scales, possibly reconciling simulations and observations; an effective interaction term between dark matter and baryons that could explain observed correlations between the two components of the cosmic fluid within Tully-Fisher analysis.Comment: 18 pages, 6 figures, references added. Published in JCA

Active Brownian Particles. From Individual to Collective Stochastic Dynamics

We review theoretical models of individual motility as well as collective dynamics and pattern formation of active particles. We focus on simple models of active dynamics with a particular emphasis on nonlinear and stochastic dynamics of such self-propelled entities in the framework of statistical mechanics. Examples of such active units in complex physico-chemical and biological systems are chemically powered nano-rods, localized patterns in reaction-diffusion system, motile cells or macroscopic animals. Based on the description of individual motion of point-like active particles by stochastic differential equations, we discuss different velocity-dependent friction functions, the impact of various types of fluctuations and calculate characteristic observables such as stationary velocity distributions or diffusion coefficients. Finally, we consider not only the free and confined individual active dynamics but also different types of interaction between active particles. The resulting collective dynamical behavior of large assemblies and aggregates of active units is discussed and an overview over some recent results on spatiotemporal pattern formation in such systems is given.Comment: 161 pages, Review, Eur Phys J Special-Topics, accepte

The MeerKAT Galaxy Cluster Legacy Survey: I. Survey overview and highlights

Please abstract in the article.The South African Radio Astronomy Observatory (SARAO), the National Research Foundation (NRF), the National Radio Astronomy Observatory, US National Science Foundation, the South African Research Chairs Initiative of the DSI/NRF, the SARAO HCD programme, the South African Research Chairs Initiative of the Department of Science and Innovation.http://www.aanda.orghj2022Physic

Effect of SGLT-1/2 inhibition on mitochondrial dysfunction in left atrial remodeling during HFpEF

Abstract Background In the DAPA-HF trial, SGLT inhibition reduces cardiovascular mortality in heart failure. However, the mechanism and a potential positive effect in HfpEF remain elusive. Introduction LA remodeling is a hallmark feature of HFpEF and commonly associated with LA enlargement and dysfunction. Previous studies of SGLT-2 inhibitor Empagliflozin suggest a utilization of alternative metabolites for energy consumption (i.e. ketone bodies). Additionally, alterations of sodium and calcium ion hemostasis have been reported. We investigated the effect of SGLT inhibition on mitochondrial (dys)function during atrial remodeling in HFpEF. Methods Rats (WT: Wistar Kyoto, HFpEF: ZFS-1 Obese (metabolic syndrome)) were obtained at ∼10w and fed Purina 5008 diet. At 17w, animals were randomized to treatment with either vehicle or Sota (30mg/kg/d) for 5w until primary adult cardiomyocytes were isolated for final experiments. Structural information of mitochondria was obtained with Mitotracker Red in either a glucose starved (1h incubation with mannitol) or saturated state. ROS production was assessed with H2-DCF in a starved and saturated condition. Mitochondrial calcium buffer capacity was imaged with Rhod-2 following perforation of the cellular membrane with saponin. Glycolytic dependency of calcium cycling was assessed upon glycolytic inhibition with 2-deoxyglucose during imaging of cytosolic calcium transients with Fura-2. Results In a glucose saturated state, LA cardiomyocytes in HFpEF showed increased mitochondrial density, which was ameliorated with Sota. Sota increased mitochondrial calcium buffer capacity in HFpEF, indicating a decrease in mitochondrial resting calcium. Differences in mitochondrial fission could not be detected. However, during glucose starvation cardiomyocytes showed a decrease in mitochondrial fission and ROS production with Sota. A difference in ROS production was not visible when cells were abruptly challenged with high glucose concentrations, but Sota decreased mitochondrial fission, indicating long term protective properties towards ROS. Glycolytic inhibition led to an increase of cytosolic diastolic calcium and calcium transient peak height in HFpEF vs. WT, indicating an increased glucose dependency of cytosolic calcium cycling, which was mitigated with Sota. Additionally, Sota negated an increase in diastolic calcium, when cardiomyocytes where challenged with high concentrations of glucose after starvation. Conclusion SGLT1/2 inhibition alters mitochondrial calcium uptake in HFpEF and positively affects mitochondrial structure with subsequent decreases of ROS production and enhanced calcium homeostasis. Funding Acknowledgement Type of funding source: Public grant(s) – National budget only. Main funding source(s): Else-Kröner-Fresenius-Stiftung, Deutsches Zentrum für Herz-Kreislaufforschung </jats:sec

The association between visual impairment and fatigue: a systematic review and meta-analysis of observational studies

Purpose: The aim was to compare fatigue levels between patients with visual impairment and controls with normal sight and to examine the association between fatigue and vision loss severity. Methods: A systematic literature search was performed using databases of PubMed, Embase, PsycINFO and Cochrane to identify observational studies with outcomes related to fatigue (e.g. vitality subscale of the Short-Form 36, Fatigue Assessment Scale). A meta-analysis was performed using standardised mean differences (SMDs) and odds ratios (OR) to quantitatively summarise the association between visual impairment and fatigue. Sources of heterogeneity were explored by subgroup and sensitivity analyses. Study quality was assessed with the Newcastle-Ottawa scale. Results: After reviewing 4477 studies, 22 studies with a total of 40 004 participants were included, of which 18 contributed to meta-analysis. Among these, eight were assessed as moderate quality studies and 10 as high quality studies. Pooled analysis involving 2500 patients and 8395 controls showed higher fatigue severity levels (S.M.D. = −0.36, 95% CI −0.50 to −0.22, 14 studies) among visually impaired patients compared to normally sighted controls. This effect size was small and persisted in sensitivity analyses that involved study quality, fatigue assessment tools and visual acuity data. Furthermore, pooled analysis of four studies including 2615 patients and 5438 controls showed a significant association between visual impairment and fatigue (OR = 2.61, 95% CI 1.69 to 4.04). Secondary meta-analysis of four studies showed no significant difference in fatigue severity (S.M.D. = 0.01, 95% CI −0.37 to 0.39) between patients with moderate visual impairment and patients with severe visual impairment or blindness. Conclusions: Current moderate to high quality evidence suggest that patients with visual impairment experience more severe fatigue symptoms than persons with normal sight. However, a limited number of available studies indicates that fatigue is not associated with severity of vision loss. Future studies are required to determine which factors and underlying mechanisms may explain the association between visual impairment and fatigue. Discussing fatigue at an early stage and developing intervention options for vision-related fatigue should be considered within the field of low vision rehabilitation