Miracle-dz/UniFAR-FTUs huggingface dataset:
The innocuousness of adiabatic instabilities in coupled scalar field‐dark matter models

Non‐minimally coupled scalar field models suffer of unstable growing modes at the linear perturbation level. The nature of these instabilities depends on the dynamical state of the scalar field. In particular in systems which admit adiabatic solutions, large scale instabilities are suppressed by the slow‐roll dynamics of the field. Here we review these results and present a preliminary likelihood data analysis suggesting that along adiabatic solutions coupled models with coupling of order of gravitational strength can provide viable cosmological scenarios satisfying constraints from SN Ia, CMB and large scale structure data.
Interpolatory Methods for Model Reduction of Large-Scale Dynamical Systems

In this thesis, we study interpolation-based model order reduction techniques for large-scale linear, bilinear and quadratic-bilinear control systems. A particular focus lies on the H2-optimal model reduction problem. Based on existing theory for linear H2-optimal model reduction, we derive several new results that find application in the approximate solution of large-scale linear matrix equations. This includes a new connection between the topic of Riemannian optimization on matrix manifolds and the concept of rational interpolation. We further propose a method for locally minimizing the residual of the Lyapunov equation for a given rank n̂. As is shown, the idea can be interpreted as a special case of the H2-optimal model order reduction problem for bilinear control systems. Moreover, for this special class of nonlinear control systems, we derive an abstract interpolation-based model reduction technique that aims at minimizing the bilinear H2-norm. New optimality conditions are computed and compared with existing ones that are based on generalized Lyapunov equations arising in the context of bilinear control theory. These matrix equations so far constituted a bottleneck within the method of balanced truncation for bilinear systems. Based on results from linear control theory, we show that under certain assumptions a fast exponential singular value decay of the solution matrix allows to approximately solve these equations via appropriate low rank methods. By means of numerical examples ranging up to dimensions n = 562 500, we demonstrate the efficiency of several new approaches. Finally, we investigate a recently introduced framework for model reduction of more general nonlinear control systems. This leads to the analysis of so-called quadratic-bilinear control systems. We show how tools and results from tensor theory can be used to improve the existing method with regard to computational efficiency as well as approximation accuracy. Again, numerical examples resulting from the spatial discretization of nonlinear partial differential equations are used to compare our method with current state-of-the-art techniques.
Oblique Wave Scattering by a Vertical Flexible Porous Plate

In the present study, oblique surface wave scattering by a submerged vertical flexible porous plate is investigated in both the cases of water of finite and infinite depths. Using Green's function technique, the boundary value problem is converted into a system of three Fredholm type integral equations. Various integrals associated with the integral equations are evaluated using appropriate Gauss quadrature formulae and the system of integral equations are converted into a system of algebraic equations. Further, using Green's second identity, expressions for the reflection and transmission coefficients are obtained in terms of the velocity potential and its normal derivative. Energy balance relations for wave scattering by flexible porous plates and permeable membrane barriers are derived using Green's identity and used to check the correctness of the computational results. From the general formulation of the submerged plate, wave scattering by partial plates such as (i) surface‐piercing and (ii) bottom‐standing plates are studied as special cases. Further, oblique wave scattering by bottom‐standing and surface‐piercing porous membrane barriers are studied in finite water depth as particular cases of the flexible plate problem. Various numerical results are presented to study the effect of structural rigidity, angle of incidence, membrane tension, structural length, porosity and water depth on wave scattering. It is found that wave reflection is more for a surface‐piercing flexible porous plate in infinite water depth compared to finite water depth and opposite trend is observed for a submerged flexible porous plate. For a surface‐piercing nonpermeable membrane, zeros in transmission coefficient are observed for waves of intermediate water depth which disappear with the inclusion of porosity. The study reveals that porosity has small influence on the wave‐induced excitation of the structure with higher flexibility but it tends to reduce the deflection of a stiffer structure. In case of partial flexible plates and membrane barriers, irrespective of the gap length, full transmission occurs due to wave diffraction through the gap in the very long wave regime while, full reflection occurs by complete flexible impermeable barriers for similar wave condition.
An observationally-driven kinetic approach to coronal heating

Coronal heating through the explosive release of magnetic energy remains an open problem in solar physics. Recent hydrodynamical models attempt an investigation by placing swarms of 'nanoflares' at random sites and times in modeled one-dimensional coronal loops. We investigate the problem in three dimensions, using extrapolated coronal magnetic fields of observed solar active regions. We apply a nonlinear force-free field extrapolation above an observed photospheric magnetogram of NOAA active region (AR) 11158. We then determine the locations, energy contents, and volumes of 'unstable' areas, namely areas prone to releasing magnetic energy due to locally accumulated electric current density. Statistical distributions of these volumes and their fractal dimension are inferred, investigating also their dependence on spatial resolution. Further adopting a simple resistivity model, we infer the properties of the fractally distributed electric fields in these volumes. Next, we monitor the evolution of 10^5 particles (electrons and ions) obeying an initial Maxwellian distribution with a temperature of 10 eV, by following their trajectories and energization when subjected to the resulting electric fields. For computational convenience, the length element of the magnetic-field extrapolation is 1 arcsec, much coarser than the particles collisional mean free path in the low corona. The presence of collisions traps the bulk of the plasma around the unstable volumes, or current sheets (UCS), with only a tail of the distribution gaining substantial energy. Assuming that the distance between UCS is similar to the collisional mean free path we find that the low active-region corona is heated to 100-200 eV, corresponding to temperatures exceeding 2 MK, within tens of seconds for electrons and thousands of seconds for ions. Fractally distributed, nanoflare-triggening fragmented UCS .
The formation of multiple populations in the globular cluster 47 Tuc

We use the combination of photometric and spectroscopic data of 47 Tuc stars to reconstruct the possible formation of a second generation of stars in the central regions of the cluster, from matter ejected from massive Asymptotic Giant Branch stars, diluted with pristine gas. The yields from massive AGB stars with the appropriate metallicity (Z=0.004, i.e. [Fe/H]=-0.75) are compatible with the observations, in terms of extension and slope of the patterns observed, involving oxygen, nitrogen, sodium and aluminium. Based on the constraints on the maximum helium of 47 Tuc stars provided by photometric investigations, and on the helium content of the ejecta, we estimate that the gas out of which second generation stars formed was composed of about one-third of gas from intermediate mass stars, with M>= 5Mo and about two-thirds of pristine gas. We tentatively identify the few stars whose Na, Al and O abundances resemble the undiluted AGB yields with the small fraction of 47 Tuc stars populating the faint subgiant branch. From the relative fraction of first and second generation stars currently observed, we estimate that the initial FG population in 47 Tuc was about 7.5 times more massive than the cluster current total mass.
Entanglement entropy in quantum impurity systems and systems with boundaries

We review research on a number of situations where a quantum impurity or a physical boundary has an interesting effect on entanglement entropy. Our focus is mainly on impurity entanglement as it occurs in one-dimensional systems with a single impurity or a boundary, in particular quantum spin models, but generalizations to higher dimensions are also reviewed. Recent advances in the understanding of impurity entanglement as it occurs in the spin-boson and Kondo impurity models are discussed along with the influence of boundaries. Particular attention is paid to (1 + 1)-dimensional models where analytical results can be obtained for the case of conformally invariant boundary conditions and a connection to topological entanglement entropy is made. New results for the entanglement in systems with mixed boundary conditions are presented. Analytical results for the entanglement entropy obtained from Fermi liquid theory are also discussed as well as several different recent definitions of the impurity contribution to the entanglement entropy.
THE COSMOGRID SIMULATION: STATISTICAL PROPERTIES OF SMALL DARK MATTER HALOS

We present the results of the “Cosmogrid” cosmological N-body simulation suites based on the concordance LCDM model. The Cosmogrid simulation was performed in a 30 Mpc box with 20483 particles. The mass of each particle is 1.28 × 105 M☉, which is sufficient to resolve ultra-faint dwarfs. We found that the halo mass function shows good agreement with the Sheth & Tormen fitting function down to ∼107 M☉. We have analyzed the spherically averaged density profiles of the three most massive halos which are of galaxy group size and contain at least 170 million particles. The slopes of these density profiles become shallower than −1 at the innermost radius. We also find a clear correlation of halo concentration with mass. The mass dependence of the concentration parameter cannot be expressed by a single power law, however a simple model based on the Press–Schechter theory proposed by Navarro et al. gives reasonable agreement with this dependence. The spin parameter does not show a correlation with the halo mass. The probability distribution functions for both concentration and spin are well fitted by the log-normal distribution for halos with the masses larger than ∼108 M☉. The subhalo abundance depends on the halo mass. Galaxy-sized halos have 50% more subhalos than ∼1011 M☉ halos have.
AN N-BODY INTEGRATOR FOR GRAVITATING PLANETARY RINGS, AND THE OUTER EDGE OF SATURN'S B RING

A new symplectic N-body integrator is introduced, one designed to calculate the global 360° evolution of a self-gravitating planetary ring that is in orbit about an oblate planet. This freely available code is called epi_int, and it is distinct from other such codes in its use of streamlines to calculate the effects of ring self-gravity. The great advantage of this approach is that the perturbing forces arise from smooth wires of ring matter rather than discreet particles, so there is very little gravitational scattering and so only a modest number of particles are needed to simulate, say, the scalloped edge of a resonantly confined ring or the propagation of spiral density waves. The code is applied to the outer edge of Saturn's B ring, and a comparison of Cassini measurements of the ring's forced response to simulations of Mimas's resonant perturbations reveals that the B ring's surface density at its outer edge is σ0 = 195 ± 60 g cm−2, which, if the same everywhere across the ring, would mean that the B ring's mass is about 90% of Mimas's mass. Cassini observations show that the B ring-edge has several free normal modes, which are long-lived disturbances of the ring-edge that are not driven by any known satellite resonances. Although the mechanism that excites or sustains these normal modes is unknown, we can plant such a disturbance at a simulated ring's edge and find that these modes persist without any damping for more than ∼105 orbits or ∼100 yr despite the simulated ring's viscosity νs = 100 cm2 s−1. These simulations also indicate that impulsive disturbances at a ring can excite long-lived normal modes, which suggests that an impact in the recent past by perhaps a cloud of cometary debris might have excited these disturbances, which are quite common to many of Saturn's sharp-edged rings.
Exact solvability of the quantum Rabi model using Bogoliubov operators

The quantum Rabi model can be solved exactly by the Bargmann transformation from real coordinate to complex variable recently [Phys. Rev. Lett. \textbf{107}, 100401 (2011)]. By the extended coherent states, we recover this solution in an alternative simpler and perhaps more physical way without uses of any extra conditions, like Bargmann conditions. In the same framework, the two-photon Rabi model are solved exactly by extended squeeze states. Transcendental functions have been derived with the similar form as those in one-photon model. Both extended coherent states and squeeze states are essentially Fock states in the space of the corresponding Bogoliubov operators. The present approach could be easily extended to study the exact solvability or integrability of various spin-boson systems with multi-level, even multi-mode.
Reward-related activation of fronto-striatal regions scaled negatively with C-reactive protein but showed no association with anhedonia in depression.

Depression is characterized by divergent changes in positive and negative affect. Emerging roles of inflammation in depression portend avenues for novel immunomodulator-based monotherapy, targeting mechanistically distinct symptoms such as anhedonia and pessimism. To investigate fundamental links between these divergent affective components and inflammation, we used a probabilistic reinforcement-learning fMRI paradigm, testing for evidence of hyposensitivity to reward, and hypersensitivity to punishment in low-inflammation depression cases (loCRP depression; CRP [≤] 3mg/L; N=48), high-inflammation depression cases (hiCRP depression; CRP > 3mg/L; N=31), and healthy controls (HC; CRP [≤] 3mg/L; N=45). We aimed to (i) determine whether depression cases with high and low inflammation showed aberrant neural activation to monetary gains and losses compared to controls; (ii) examine if these alterations correlated with a continuous measure of C-reactive protein (CRP) in depression, (iii) test if neuroimaging responses to rewards and punishments scaled with indices of anhedonia and pessimism derived from behavioral instruments in depression. Voxel-wise activation was observed in key brain regions sensitive to monetary reward (ventromedial prefrontal cortex, vmPFC; nucleus accumbens, NAc) and punishment (insula) outcomes across all three groups. However, there was no significant difference in activation between groups. Within depression cases, increasing CRP scaled negatively with activation in the right vmPFC and left NAc but not insula cortex. However, there was no significant association between regional activation and severity of anhedonia or pessimism. Our results support the previously reported association between CRP and striatal reward reactivity in depression but do not extend this to processing of negatively valenced information.
Attained body mass index among children attending outdoor or conventional kindergartens

BACKGROUND: Studies have shown that outdoor activities are inversely associated with adiposity, but little is known about outdoor kindergartens as a potential intervention for healthy weight development. METHODS: We included 1544 children from outdoor kindergartens and 1640 from conventional kindergartens. Anthropometry was measured by school health nurses when the children were 6 to 8 years old. The first available measure of attained body mass index z-score (BMIz) after school entrance was included as the primary outcome, while risk of attaining overweight (including obesity) was included as a secondary outcome. Register-based information was available on potential confounding factors. Regression models were constructed to examine differences in study outcomes between children attending outdoor and conventional kindergartens. RESULTS: Our basic models, with information on outcome, kindergarten type and birth weight, showed a borderline statistically significantly lower attained BMIz (-0.07 [95% CI: -0.14, 0.00], P=0.060) and a lower risk of overweight (adjusted risk ratio: 0.83 [95% CI: 0.72, 0.97], P=0.016) among children attending outdoor kindergartens compared to conventional kindergartens. When additionally adjusting for sociodemographic factors, there was no evidence of differences in attained BMIz (P=0.153) or overweight (P=0.967). CONCLUSION: Our results do not support outdoor kindergartens as an intervention for healthy weight development.
Excitation-inhibition imbalance in Alzheimer's disease using multiscale neural model inversion of resting-state fMRI

Alzheimer's disease (AD) is a serious neurodegenerative disorder without a clear understanding of the etiology and pathophysiology. Recent experimental data has suggested excitation-inhibition (E-I) imbalance as an essential element and critical regulator of AD pathology, but E-I imbalance has not been systematically mapped out in both local and large-scale neuronal circuits in AD. Using a multiscale neural model inversion framework, we identified disrupted E-I balance as well as impaired excitatory and inhibitory connections in a large network during AD progression based on resting-state functional MRI data from the Alzheimer's Disease Neuroimaging Initiative (ADNI) database. We observed that E-I balance is progressively disrupted from mild cognitive impairment (MCI) to AD and alteration of E-I balance is bidirectional varying from region to region. Also, we found that inhibitory connections are more significantly impaired than excitatory connections and the strength of the majority of excitatory and inhibitory connections reduces in MCI and AD, leading to gradual decoupling of neural populations. Moreover, we revealed a core AD network comprising mainly of limbic and cingulate regions including the hippocampus, pallidum, putamen, nucleus accumbens, inferior temporal cortex and caudal anterior cingulate cortex. These brain regions exhibit consistent and stable E-I alteration across MCI and AD, which may represent a stable AD biomarker and an important therapeutic target. Overall, our study constitutes the first attempt to delineate E-I imbalance in large-scale neuronal circuits during AD progression, which facilitates the development of new treatment paradigms to restore pathological E-I balance in AD.
Effect of platelet-rich plasma scaffolding combined with osteochondral autograft transfer for full-thickness articular cartilage defects of the femoral condyle

We aimed to investigate the local application methods of platelet-rich plasma (PRP) and the effect and safety of PRP scaffolding combined with osteochondral autograft transfer (OAT) in the treatment of full-thickness articular cartilage defects of the femoral condyle. Patients with cartilage defects of the femoral condyle were treated with OAT combined with PRP scaffolding between July 2017 and December 2020. Preoperative magnetic resonance imaging (MRI) and computed tomography were utilized to assess the size, location, and severity of the osteochondral defects. X-ray and MRI images of the knee were obtained at the final follow-up to assess the osseointegration and integrity of the implanted articular cartilage. Osteoarthritic changes in the knee joint were evaluated using the Kellgren–Lawrence grading system. Clinical status was assessed using the visual analog scale (VAS), International Knee Documentation Committee (IKDC), and Lysholm scores before the treatment and at the final follow-up. Complications and patient satisfaction were recorded to assess the safety of this combination therapy. Twenty-one patients were recruited, with a mean follow-up duration of 18.23 ± 6.84 months. The mean lesion size was 2.3 ± 0.59 cm2. The mean platelet concentration in PRP at baseline was 6.27 ± 0.63 times greater than that in the peripheral blood. The VAS, IKDC, and Lysholm scores had improved significantly at the final follow-up (P < 0.001). No serious complications such as joint infection, deep venous thrombosis, or hematoma were observed. Eighteen patients (85.72%) were satisfied with their knee function and quality of life at the final follow-up. Three patients (14.28%) complained of mild anterior knee pain, which was relieved by oral administration of nonsteroidal anti-inflammatory drugs. MRI examinations of all patients showed bony consolidation and the defect surface was covered with cartilage-like tissue. X-ray evaluations indicated that osteoarthritis in two knees (9.5%) had progressed from grade 1 to grade 2 at the final follow-up. The preliminary results showed that OAT combined with PRP may be a safe and effective technique for the treatment of full-thickness articular cartilage defects in the knee.
RESONANT ABSORPTION OF TRANSVERSE OSCILLATIONS AND ASSOCIATED HEATING IN A SOLAR PROMINENCE. II. NUMERICAL ASPECTS

Transverse magnetohydrodynamic (MHD) waves are ubiquitous in the solar atmosphere and may be responsible for generating the Sun’s million-degree outer atmosphere. However, direct evidence of the dissipation process and heating from these waves remains elusive. Through advanced numerical simulations combined with appropriate forward modeling of a prominence flux tube, we provide the observational signatures of transverse MHD waves in prominence plasmas. We show that these signatures are characterized by a thread-like substructure, strong transverse dynamical coherence, an out-of-phase difference between plane-of-the-sky motions and line-of-sight velocities, and enhanced line broadening and heating around most of the flux tube. A complex combination between resonant absorption and Kelvin–Helmholtz instabilities (KHIs) takes place in which the KHI extracts the energy from the resonant layer and dissipates it through vortices and current sheets, which rapidly degenerate into turbulence. An inward enlargement of the boundary is produced in which the turbulent flows conserve the characteristic dynamics from the resonance, therefore guaranteeing detectability of the resonance imprints. We show that the features described in the accompanying paper through coordinated Hinode and Interface Region Imaging Spectrograph observations match the numerical results well.