ABSTRACT
Non-thermal emission from relativistic cosmic ray (CR) electrons gives insight into the strength and morphology of intra-cluster magnetic fields, as well as providing powerful tracers of ...structure formation shocks. Emission caused by CR protons on the other hand still challenges current observations and is therefore testing models of proton acceleration at intra-cluster shocks. Large-scale simulations including the effects of CRs have been difficult to achieve and have been mainly reduced to simulating an overall energy budget, or tracing CR populations in post-processing of simulation output and has often been done for either protons or electrons. We introduce crescendo: Cosmic Ray Evolution with SpeCtral Electrons aND prOtons, an efficient on-the-fly Fokker–Planck solver to evolve distributions of CR protons and electrons within every resolution element of our simulation. The solver accounts for CR (re-)acceleration at intra-cluster shocks, based on results of recent particle-in-cell simulations, adiabatic changes, and radiative losses of electrons. We show its performance in test cases as well as idealized galaxy cluster (GC) simulations. We apply the model to an idealized GC merger following best-fitting parameters for CIZA J2242.4 + 5301-1 and study CR injection, radio relic morphology, spectral steepening, and synchrotron emission.
Spectral variable selection is an important step in spectroscopic data analysis, as it tends to parsimonious data representation and can result in multivariate models with greater predictive ability. ...In this study, we used VIS-NIR (visible to near-infrared) diffuse reflectance and DRIFT (diffuse reflectance infrared Fourier transform in the mid-infrared range, MIR) spectroscopy to determine a series of chemical and biological soil properties. Multivariate calibrations were performed with partial least squares regression (PLSR) using the full absorbance spectra (VIS-NIR: 400–2500nm with 5-nm intervals; MIR: 4000–800cm−1 with 4-cm−1 intervals) and with a combination of PLSR and CARS (competitive adaptive reweighted sampling) to integrate only the most informative key variables. The CARS procedure has as yet not been applied in the field of soil spectroscopy. As set heterogeneity is crucial for an optimal calibration, we tested these approaches to a sample set of 60 agricultural samples covering a broad range of different parent materials, soil textures, organic matter contents and soil pH values. Soil samples were taken from the Ap horizon (0–10cm depth), air-dried and pulverised before the lab spectroscopic measurements were performed. In a cross-validation approach, the CARS–PLSR method was markedly more accurate than full spectrum-PLSR for all investigated soil variables and both spectral regions. With MIR data and CARS–PLSR, excellent results (indicated by a residual prediction deviation (RPD) greater than 3.0) were obtained for organic carbon (OC), nitrogen (N), microbial biomass-C (Cmic) and pH values; for hot water extractable C (Chwe), RPD was 2.60. The accuracies obtained with VIS-NIR data were considerably lower than those with the MIR spectra; best results were retrieved for pH and Cmic (approximately quantitative as indicated by RPD values between 2.0 and 2.5). The information content of the MIR data was substantially different from the VIS-NIR information, as indicated by 2D correlation analysis. We found an overall blurred 2D correlation pattern between both spectral regions with moderate to low correlation coefficients, which suggested that the heterogeneity of the studied soil sample population had led to a very complex blurring of overtones and combination bands in the NIR region.
Statistical CARS selections were physically reasonable. MIR key wavenumbers for the studied C fractions were inter alia identified at the bands at 2920cm−1 and 2850cm−1 (both aliphatic CH-groups) and the region between 1740 and 1600cm−1 (CO-groups) and represent hydrophobic and hydrophilic compounds of soil organic matter. Important VIS-NIR wavelengths for assessing C fractions and N were located nearby the prominent water absorption band at 1915nm and the hydroxyl band at 2200nm.
The simplicity of the approach, parsimony of the multivariate models, accuracy levels in the cross-validation and physically reasonable selections indicated a successful operation of the CARS procedure. It should be further examined with a larger number of samples using separate calibration and validation sets.
•Informative key spectral variables were effectively selected with the CARS method.•CARS–PLSR improved cross-validated accuracies compared to full spectrum-PLSR.•Statistically selected MIR wavenumbers matched with bands of relevant functional groups.•2D-correlations did not reflect physical couplings between MIR and NIR regions.
Abstract
We investigate shock structures driven by merger events in high-resolution simulations that result in a galaxy with a virial mass
M
≈ 10
12
M
⊙
. We find that the sizes and morphologies of ...the internal shocks resemble remarkably well those of the newly detected class of odd radio circles (ORCs). This would highlight a so-far overlooked mechanism to form radio rings, shells, and even more complex structures around elliptical galaxies. Mach numbers of
= 2–3 for such internal shocks are in agreement with the spectral indices of the observed ORCs. We estimate that ∼5% of galaxies could undergo merger events, which occasionally lead to such prominent structures within the galactic halo during their lifetime, explaining the low number of observed ORCs. At the time when the shock structures are matching the physical sizes of the observed ORCs, the central galaxies are typically classified as early-type galaxies, with no ongoing star formation, in agreement with observational findings. Although the energy released by such mergers could potentially power the observed radio luminosity already in Milky Way–like halos, our predicted luminosity from a simple, direct shock acceleration model is much smaller than the observed one. Considering the estimated number of candidates from our cosmological simulations and the higher observed energies, we suggest that the proposed scenario is more likely for halo masses around 10
13
M
⊙
in agreement with the observed stellar masses of the galaxies at the center of ORCs. Such shocks might be detectable with next-generation X-ray instruments like the Line Emission Mapper (LEM).
Abstract
Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has spread rapidly worldwide. Given scarce resources, nonlaboratory diagnostics ...are crucial. In this cross-sectional study, two-thirds of European patients with confirmed COVID-19 reported olfactory and gustatory dysfunction, indicating the significance of these symptoms in early diagnostics.
Abstract
Radio relics are typically found to be arc-like regions of synchrotron emission in the outskirts of merging galaxy clusters, bowing out from the cluster center. In most cases they show ...synchrotron spectra that steepen toward the cluster center, indicating that they are caused by relativistic electrons being accelerated at outward traveling merger shocks. A number of radio relics break with this ideal picture and show morphologies that are bent the opposite way and show spectral index distributions that do not follow expectations from the ideal picture. We propose that these “wrong way” relics can form when an outward traveling shock wave is bent inward by an infalling galaxy cluster or group. We test this in an ultra-high-resolution zoom-in simulation of a massive galaxy cluster with an on-the-fly spectral cosmic-ray model. This allows us to study not only the synchrotron emission at colliding shocks, but also their synchrotron spectra to address the open question of relics with strongly varying spectral indices over the relic surface.
Abstract
We present non-radiative, cosmological zoom-in simulations of galaxy-cluster formation with magnetic fields and (anisotropic) thermal conduction of one massive galaxy cluster with
M
vir
∼ 2 ...× 10
15
M
⊙
at
z
∼ 0. We run the cluster on three resolution levels (1×, 10×, 25×), starting with an effective mass resolution of 2 × 10
8
M
⊙
, subsequently increasing the particle number to reach 4 × 10
6
M
⊙
. The maximum spatial resolution obtained in the simulations is limited by the gravitational softening reaching
ϵ
= 1.0 kpc at the highest resolution level, allowing one to resolve the hierarchical assembly of the structures in fine detail. All simulations presented are carried out with the SPMHD code
gadget3
with an updated SPMHD prescription. The primary focus of this paper is to investigate magnetic field amplification in the intracluster medium. We show that the main amplification mechanism is the small-scale turbulent dynamo in the limit of reconnection diffusion. In our two highest resolution models we start to resolve the magnetic field amplification driven by the dynamo and we explicitly quantify this with the magnetic power spectra and the curvature of the magnetic field lines, consistent with dynamo theory. Furthermore, we investigate the ∇ ·
B
= 0 constraint within our simulations and show that we achieve comparable results to state-of-the-art AMR or moving-mesh techniques, used in codes such as
enzo
and
arepo
. Our results show for the first time in a cosmological simulation of a galaxy cluster that dynamo action can be resolved with modern numerical Lagrangian magnetohydrodynamic methods, a study that is currently missing in the literature.
Abstract We present the first results of one extremely high-resolution, nonradiative magnetohydrodynamical cosmological zoom-in simulation of a massive cluster with a virial mass of M vir = 2.0 × 10 ...15 solar masses. We adopt a mass resolution of 4 × 10 5 M ⊙ with a maximum spatial resolution of around 250 pc in the central regions of the cluster. We follow the detailed amplification process in a resolved small-scale turbulent dynamo in the intracluster medium (ICM) with strong exponential growth until redshift 4, after which the field grows weakly in the adiabatic compression limit until redshift 2. The energy in the field is slightly reduced as the system approaches redshift zero in agreement with adiabatic decompression. The field structure is highly turbulent in the center and shows field reversals on a length scale of a few tens of kiloparsecs and an anticorrelation between the radial and angular field components in the central region that is ordered by small-scale turbulent dynamo action. The large-scale field on megaparsec scales is almost isotropic, indicating that the structure formation process in massive galaxy cluster formation suppresses any memory of both the initial field configuration and the amplified morphology via the turbulent dynamo. We demonstrate that extremely high-resolution simulations of the magnetized ICM are within reach that can simultaneously resolve the small-scale magnetic field structure, which is of major importance for the injection of and transport of cosmic rays in the ICM. This work is a major cornerstone for follow-up studies with an on-the-fly treatment of cosmic rays to model in detail electron-synchrotron and gamma-ray emissions.
Hip fracture is a common, morbid, and costly event among older adults. Data are inconclusive as to whether epidural or spinal (regional) anesthesia improves outcomes after hip fracture surgery.
The ...authors examined a retrospective cohort of patients undergoing surgery for hip fracture in 126 hospitals in New York in 2007 and 2008. They tested the association of a record indicating receipt of regional versus general anesthesia with a primary outcome of inpatient mortality and with secondary outcomes of pulmonary and cardiovascular complications using hospital fixed-effects logistic regressions. Subgroup analyses tested the association of anesthesia type and outcomes according to fracture anatomy.
Of 18,158 patients, 5,254 (29%) received regional anesthesia. In-hospital mortality occurred in 435 (2.4%). Unadjusted rates of mortality and cardiovascular complications did not differ by anesthesia type. Patients receiving regional anesthesia experienced fewer pulmonary complications (359 6.8% vs. 1,040 8.1%, P < 0.005). Regional anesthesia was associated with a lower adjusted odds of mortality (odds ratio: 0.710, 95% CI 0.541, 0.932, P = 0.014) and pulmonary complications (odds ratio: 0.752, 95% CI 0.637, 0.887, P < 0.0001) relative to general anesthesia. In subgroup analyses, regional anesthesia was associated with improved survival and fewer pulmonary complications among patients with intertrochanteric fractures but not among patients with femoral neck fractures.
Regional anesthesia is associated with a lower odds of inpatient mortality and pulmonary complications among all hip fracture patients compared with general anesthesia; this finding may be driven by a trend toward improved outcomes with regional anesthesia among patients with intertrochanteric fractures.
The objective of using supplementary cementitious materials (SCMs) in cement is to reduce costs and the overall CO2 output of the cement production. Against the background of an increasing demand for ...cement and a decreasing availability of common SCMs, calcined clays serve as alternative material for the industrial-scale manufacture of composite cements. In the presented study, a raw bentonite clay of high volume capacity and small exploitation options was selected to check its pozzolanic activity after suitable thermal treatment and the consequent effects on the concrete performance. The results show that, at high cement substitution rates of 30%, the properties of the concrete were not changed to a significant extent. In certain durability issues namely sulphate resistance, inhibition of alkali silica reaction (ASR) and chloride migration, the mixture with calcined clay even performed better than the reference. Other properties like final strength and frost and de-icing salt resistance were changed in an uncritical way. Negative effects were observed on the early strengths and on the carbonation velocity. However, giving careful consideration to these aspects during concrete projecting, the calcined clay would be a suitable material for the majority of concrete applications.
•Calcined clay production features low costs and low CO2 output.•Bentonites serve as excellent raw materials for production of pozzolanic SCMs.•Up to 30% of clinker can be substituted without quality loss of cement.•With careful choice of calcining temperature, no impairment of workability occurs.•Concrete porosity is refined so that most durability properties are improved.
PDF
