We simulate the multiphase interstellar medium (ISM) randomly heated and stirred by supernovae (SNe), with gravity, differential rotation and other parameters of the solar neighbourhood. Here we ...describe in detail both numerical and physical aspects of the model, including injection of thermal and kinetic energy by SN explosions, radiative cooling, photoelectric heating and various transport processes. With a three-dimensional domain extending 1 × 1 kpc2 horizontally and 2 kpc vertically (symmetric about the galactic mid-plane), the model routinely spans gas number densities 10−5-102 cm−3, temperatures 10-108 K and local velocities up to 103 km s−1 (with Mach number up to 25). The working numerical resolution of 4 pc has been selected via simulations of a single expanding SN remnant, where we closely reproduce, at this resolution, analytical solutions for the adiabatic and snowplough regimes. The feedback of the halo on the disc cannot be captured in our model where the domain only extends to the height of 1 kpc above the mid-plane. We argue that to reliably model the disc-halo connections would require extending the domain horizontally as well as vertically due to the increasing horizontal scale of the gas flows with height.
The thermal structure of the modelled ISM is classified by inspection of the joint probability density of the gas number density and temperature. We confirm that most of the complexity can be captured in terms of just three phases, separated by temperature borderlines at about 103 and 5 × 105 K. The probability distribution of gas density within each phase is approximately lognormal. We clarify the connection between the fractional volume of a phase and its various proxies, and derive an exact relation between the fractional volume and the filling factors defined in terms of the volume and probabilistic averages. These results are discussed in both observational and computational contexts. The correlation scale of the random flows is calculated from the velocity autocorrelation function; it is of the order of 100 pc and tends to grow with distance from the mid-plane. We use two distinct parametrizations of radiative cooling to show that the multiphase structure of the gas is robust, as it does not depend significantly on this choice.
Vortex motions are frequently observed on the solar photosphere. These motions may play a key role in the transport of energy and momentum from the lower atmosphere into the upper solar atmosphere, ...contributing to coronal heating. The lower solar atmosphere also consists of complex networks of flux tubes that expand and merge throughout the chromosphere and upper atmosphere. We perform numerical simulations to investigate the behavior of vortex-driven waves propagating in a pair of such flux tubes in a non-force-free equilibrium with a realistically modeled solar atmosphere. The two flux tubes are independently perturbed at their footpoints by counter-rotating vortex motions. When the flux tubes merge, the vortex motions interact both linearly and nonlinearly. The linear interactions generate many small-scale transient magnetic substructures due to the magnetic stress imposed by the vortex motions. Thus, an initially monolithic tube is separated into a complex multithreaded tube due to the photospheric vortex motions. The wave interactions also drive a superposition that increases in amplitude until it exceeds the local Mach number and produces shocks that propagate upward with speeds of approximately 50 km s−1. The shocks act as conduits transporting momentum and energy upward, and heating the local plasma by more than an order of magnitude, with a peak temperature of approximately 60,000 K. Therefore, we present a new mechanism for the generation of magnetic waveguides from the lower solar atmosphere to the solar corona. This wave guide appears as the result of interacting perturbations in neighboring flux tubes. Thus, the interactions of photospheric vortex motions is a potentially significant mechanism for energy transfer from the lower to upper solar atmosphere.
Although CD4+ T cells are known to contribute to the pathology of atopic dermatitis (AD) and psoriasis, the role of CD8+ T cells in these diseases remains poorly characterized. The aim of this study ...was to characterize the cytokine production of T cells from AD and psoriasis skin. We found that CD4+ T cells isolated from AD skin were largely Th2 (T helper type 2) biased, in agreement with prior reports. However, we also observed large numbers of CD8+ T cells producing IL-13, IFN-γ, and IL-22. We observed increased numbers of CD8+ T cells isolated from AD skin, and immunohistochemistry studies confirmed the presence of CD8+ T cells in the dermis and epidermis of AD skin lesions. Surprisingly, T-cell cytokine production was similar in the lesional and nonlesional skin of patients with AD. T cells from psoriatic lesional skin predominantly produced IFN-γ, IL-17, and IL-22, in agreement with prior studies. However, in addition to Th17 cells, we observed high percentages of CD8+ T cells that produced both IL-22 and IL-17 in psoriatic skin lesions. Our findings demonstrate that CD8+ T cells are a significant and previously unappreciated source of inflammatory cytokine production in both AD and psoriasis.
The origin and structure of the magnetic fields in the interstellar medium of spiral galaxies is investigated with 3D, non-ideal, compressible magnetohydrodynamic simulations, including ...stratification in the galactic gravity field, differential rotation and radiative cooling. A rectangular domain, 1 × 1 × 2 kpc3 in size, spans both sides of the galactic mid-plane. Supernova explosions drive transonic turbulence. A seed magnetic field grows exponentially to reach a statistically steady state within 1.6 Gyr. Following Germano (1992), we use volume averaging with a Gaussian kernel to separate magnetic field into a mean field and fluctuations. Such averaging does not satisfy all Reynolds rules, yet allows a formulation of mean-field theory. The mean field thus obtained varies in both space and time. Growth rates differ for the mean-field and fluctuating field and there is clear scale separation between the two elements, whose integral scales are about 0.7 and 0.3 kpc, respectively.
The value of serum human epididymis protein 4 (HE4) in guiding referral decisions in patients with an ovarian mass remains unclear, because the majority of studies investigating HE4 were performed in ...oncology hospitals. However, the decision to refer is made at general hospitals with a low ovarian cancer prevalence. We assessed accuracies of HE4 in differentiating benign or borderline from malignant tumors in patients presenting with an ovarian mass at general hospitals.
Patients with an ovarian mass were prospectively included between 2017 and 2021 in nine general hospitals. HE4 and CA125 were preoperatively measured and the risk of malignancy index (RMI) was calculated. Histological diagnosis was the reference standard.
We included 316 patients, of whom 195 had a benign, 39 had a borderline and 82 had a malignant ovarian mass. HE4 had the highest AUC of 0.80 (95%CI 0.74–0.86), followed by RMI (0.71, 95%CI 0.64–0.78) and CA125 (0.69, 95%CI 0.62–0.75). Clinical setting significantly influenced biomarker performances. Applying age-dependent cut-off values for HE4 resulted in a better performance than one cut-off. Addition of HE4 to RMI resulted in a 32% decrease of unnecessary referred patients, while the number of correctly referred patients remained the same.
HE4 is superior to RMI in predicting malignancy in patients with an ovarian mass from general hospitals. The addition of HE4 to the RMI improved HE4 alone. Although, there is still room for improvement, HE4 can guide referral decisions in patients with an ovarian mass to an oncology hospital.
•HE4 was superior to RMI in predicting malignancy in patients with an ovarian mass from general hospitals•The addition of HE4 to RMI improved the performance of HE4 alone•Combined HE4 and RMI had a 32% higher specificity than RMI while sensitivities were similar•Clinical setting significantly influences biomarker performances in predicting malignancy in patients with an ovarian mass
A single open magnetic flux tube spanning the solar photosphere (solar radius R) and the lower corona (R + 10 Mm) is modelled in magnetohydrostatic equilibrium within a realistic stratified ...atmosphere subject to solar gravity. Such flux tubes are observed to remain relatively stable for up to a day or more, and it is our aim to apply the model as the background condition for numerical studies of energy transport mechanisms from the surface to the corona. We solve analytically an axially symmetric 3D structure for the model, with magnetic field strength, plasma density, pressure and temperature all consistent with observational and theoretical estimates. The self-similar construction ensures the magnetic field is divergence free. The equation of pressure balance for this particular set of flux tubes can be integrated analytically to find the pressure and density corrections required to preserve the magnetohydrostatic equilibrium. The model includes a number of free parameters, which makes the solution applicable to a variety of other physical problems and it may therefore be of more general interest.
We apply correlation analysis to random fields in numerical simulations of the supernova-driven interstellar medium (ISM) with the magnetic field produced by dynamo action. We solve the ...magnetohydrodynamic (MHD) equations in a shearing Cartesian box representing a local region of the ISM, subject to thermal and kinetic energy injection by supernova explosions, and parameterized, optically thin radiative cooling. We consider the cold, warm, and hot phases of the ISM separately; the analysis mostly considers the warm gas, which occupies the bulk of the domain. Various physical variables have different correlation lengths in the warm phase: 40 , 50 , and 60 pc for the random magnetic field, density, and velocity, respectively, in the midplane. The correlation time of the random velocity is comparable to the eddy turnover time, about 10 7 year , although it may be shorter in regions with a higher star formation rate. The random magnetic field is anisotropic, with the standard deviations of its components b x b y b z having approximate ratios 0.5 0.6 0.6 in the midplane. The anisotropy is attributed to the global velocity shear from galactic differential rotation and locally inhomogeneous outflow to the galactic halo. The correlation length of Faraday depth along the z axis, 120 pc , is greater than for electron density, 60 - 90 pc , and the vertical magnetic field, 60 pc . Such comparisons may be sensitive to the orientation of the line of sight. Uncertainties of the structure functions of synchrotron intensity rapidly increase with the scale. This feature is hidden in a power spectrum analysis, which can undermine the usefulness of power spectra for detailed studies of interstellar turbulence.
ABSTRACT
We explore the effect of magnetic fields on the vertical distribution and multiphase structure of the supernova-driven interstellar medium in simulations that admit dynamo action. As the ...magnetic field is amplified to become dynamically significant, gas becomes cooler and its distribution in the disc becomes more homogeneous. We attribute this to magnetic quenching of vertical velocity, which leads to a decrease in the cooling length of hot gas. A non-monotonic vertical distribution of the large-scale magnetic field strength, with the maximum at |z| ≈ 300 pc causes a downward pressure gradient below the maximum which acts against outflow driven by SN explosions, while it provides pressure support above the maximum.
We present high-resolution (1024 3) simulations of super-/hypersonic isothermal hydrodynamic turbulence inside an interstellar molecular cloud (resolving scales of typically 20-100 au), including a ...multidisperse population of dust grains, i.e. a range of grain sizes is considered. Due to inertia, large grains (typical radius a ≳ 1.0μm) will decouple from the gas flow, while small grains (al∼ 0.1μm) will tend to better trace the motions of the gas. We note that simulations with purely solenoidal forcing show somewhat more pronounced decoupling and less clustering compared to simulations with purely compressive forcing. Overall, small and large grains tend to cluster, while intermediate-size grains show essentially a random isotropic distribution. As a consequence of increased clustering, the grain-grain interaction rate is locally elevated; but since small and large grains are often not spatially correlated, it is unclear what effect this clustering would have on the coagulation rate. Due to spatial separation of dust and gas, a diffuse upper limit to the grain sizes obtained by condensational growth is also expected, since large (decoupled) grains are not necessarily located where the growth species in the molecular gas is.
We test the sensitivity of hydrodynamic and magnetohydrodynamic turbulent convection simulations with respect to Mach number, thermal and magnetic boundary conditions, and the centrifugal force. We ...find that varying the luminosity, which also controls the Mach number, has only a minor effect on the large-scale dynamics. A similar conclusion can also be drawn from the comparison of two formulations of the lower magnetic boundary condition with either vanishing electric field or current density. The centrifugal force has an effect on the solutions, but only if its magnitude with respect to acceleration due to gravity is by two orders of magnitude greater than in the Sun. Finally, we find that the parameterisation of the photospheric physics, either by an explicit cooling term or enhanced radiative diffusion, is more important than the thermal boundary condition. In particular, runs with cooling tend to lead to more anisotropic convection and stronger deviations from the Taylor-Proudman state. In summary, the fully compressible approach taken here with the Pencil Code is found to be valid, while still allowing the disparate timescales to be taken into account.
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