Miracle-dz/UniFAR-FTUs huggingface dataset:
Asymptotic stability for viscous conservation law on the half line and its application (Mathematical Analysis in Fluid and Gas Dynamics)

Abstract In this talk, we consider two different topics about viscous conservation law. In the first half, we consider the way of analysis for viscous conservation law on the self-similar line, and in the second half, we present the topic of radial symmetric solution of Burgers equation. The first part of this research is a joint work with Professor Heinrich Freist\"uhler in Konstanz university.
Decoding X-ray observations from centres of galaxy clusters using MCMC

Traditionally the thermodynamic profiles (gas density, temperature, etc.) of galaxy clusters are obtained by assuming spherical symmetry and modelling projected X-ray spectra in each annulus. The outer annuli contribute to the inner ones and their contribution needs to be subtracted to obtain the temperature and density of spherical shells. The usual deprojection methods lead to propagation of errors from outside to in and typically do not model the covariance of parameters in different radial shells. In this paper we describe a method based on a free-form model of clusters with cluster parameters (density, temperature) given in spherical shells, which we jointly forward fit to the X-ray data by constructing a Bayesian posterior probability distribution that we sample using the MCMC technique. By systematically marginalizing over the nuisance outer shells, we estimate the inner entropy profiles of clusters and fit them to various models for a sample of Chandra X-ray observations of 17 clusters. We show that the entropy profiles in almost all of our clusters are best described as cored power laws. A small subsample is found to be either consistent with a power law, or alternatively their cores are not fully resolved (smaller than, or about few kpc). We find marginal evidence for bimodality in the central values of entropy (and cooling time) corresponding to cool-core and non cool-core clusters. The minimum value of the ratio of the cooling time and the free-fall time (mint(cool)/t(ff)]; correlation is much weaker with core entropy) is anti-correlated with H alpha and radio luminosity. H alpha emitting cold gas is absent in our clusters with min(t(cool)/t(ff)) a parts per thousand(3) 10. Our lowest core entropies are systematically and substantially lower than the values quoted by the ACCEPT sample.
Imaging a boson star at the Galactic center

Millimeter very long baseline interferometry will soon produce accurate images of the closest surroundings of the supermassive compact object at the center of the Galaxy, Sgr A*. These images may reveal the existence of a central faint region, the so-called shadow, which is often interpreted as the observable consequence of the event horizon of a black hole. In this paper, we compute images of an accretion torus around Sgr A* assuming this compact object is a boson star, i.e. an alternative to black holes within general relativity, with no event horizon and no hard surface. We show that very relativistic rotating boson stars produce images extremely similar to Kerr black holes, showing in particular shadow-like and photon-ring-like structures. This result highlights the extreme difficulty of unambiguously telling the existence of an event horizon from strong-field images.
Pan evaporation is increased by submerged macrophytes

Abstract. The topic of evaporation estimates is fundamental to land-surface hydrology. In this study, FAO-56 Penman–Monteith equation (FAO56–PM), multiple stepwise regression (MLR), and Kohonen self-organising map (K–SOM) techniques were used for the estimation of daily pan evaporation (Ep) in three treatments, where C was the standard class A pan with top water, S was a pan with sediment covered bottom, and SM was class A pan containing submerged macrophytes (Myriophyllum spicatum, Potamogeton perfoliatus, and Najas marina), at Keszthely, Hungary, in a six-season experiment, between 2015 and 2020. The modelling approach included six measured meteorological variables. Average Ep varied from 0.6 to 6.9 mm d−1 for C, 0.7 to 7.9 mm d−1 for S, and from 0.9 to 8.2 mm d−1 for SM during the growing seasons studied. Correlation analysis and K–SOM visual representation revealed that air temperature and global radiation had positive correlation, while relative humidity had a negative correlation with the Ep of C, S, and SM. The results showed that the MLR method provided close compliance (R2=0.58–0.62) with the observed pan evaporation values, but the K–SOM method (R2=0.97–0.98) yielded by far the closest match to observed evaporation estimates for all three pans. To our best knowledge, no similar work has been published previously using the three modelling methods for seeded pan evaporation estimation. The current study differs from previous evaporation estimates by using neural networks even with those pans containing sediments and submerged macrophytes. Their evaporation will be treated directly by K–SOM, in which the modelling is more than the simple Ep of a class A pan filled with clean tap water.
DETECTION OF FLUX EMERGENCE, SPLITTING, MERGING, AND CANCELLATION OF NETWORK FIELD. I. SPLITTING AND MERGING

Frequencies of magnetic patch processes on the supergranule boundary, namely, flux emergence, splitting, merging, and cancellation, are investigated through automatic detection. We use a set of line-of-sight magnetograms taken by the Solar Optical Telescope (SOT) on board the Hinode satellite. We found 1636 positive patches and 1637 negative patches in the data set, whose time duration is 3.5 hr and field of view is 112″ × 112″. The total numbers of magnetic processes are as follows: 493 positive and 482 negative splittings, 536 positive and 535 negative mergings, 86 cancellations, and 3 emergences. The total numbers of emergence and cancellation are significantly smaller than those of splitting and merging. Further, the frequency dependence of the merging and splitting processes on the flux content are investigated. Merging has a weak dependence on the flux content with a power-law index of only 0.28. The timescale for splitting is found to be independent of the parent flux content before splitting, which corresponds to ∼33 minutes. It is also found that patches split into any flux contents with the same probability. This splitting has a power-law distribution of the flux content with an index of −2 as a time-independent solution. These results support that the frequency distribution of the flux content in the analyzed flux range is rapidly maintained by merging and splitting, namely, surface processes. We suggest a model for frequency distributions of cancellation and emergence based on this idea.
SYSTEMATIC CENTER-TO-LIMB VARIATION IN MEASURED HELIOSEISMIC TRAVEL TIMES AND ITS EFFECT ON INFERENCES OF SOLAR INTERIOR MERIDIONAL FLOWS

We report on a systematic center-to-limb variation in measured helioseismic travel times, which must be taken into account for an accurate determination of solar interior meridional flows. The systematic variation, found in time–distance helioseismology analysis using SDO/HMI and SDO/AIA observations, is different in both travel-time magnitude and variation trend for different observables. It is not clear what causes this systematic effect. Subtracting the longitude-dependent east–west travel times, obtained along the equatorial area, from the latitude-dependent north–south travel times, obtained along the central meridian area, gives remarkably similar results for different observables. We suggest this as an effective procedure for removing the systematic center-to-limb variation. The subsurface meridional flows obtained from inversion of the corrected travel times are approximately 10 m s−1 slower than those obtained without removing the systematic effect. The detected center-to-limb variation may have important implications in the derivation of meridional flows in the deep interior and needs to be better understood.
Characteristics of solar-like oscillations of secondary red-clump stars

We calculated the populations of core-helium-burning (CHeB) stars and found that secondary red-clump (SRC) stars can form a SRC peak in the distributions of the frequency of maximum seismic amplitude (νmax) and mean large-frequency separation (Δν) of CHeB stars when metallicity Z≥ 0.02. The νmax and Δν of CHeB stars are dependent not only on He-core mass but also on H-shell burning. The SRC peak is composed of CHeB stars with mass roughly between the critical mass MHeF and MHeF+ 0.2, while He-core mass is between about 0.33 and 0.36 M⊙. The location of the SRC peak can be affected by the mixing-length parameter α, metallicity Z and overshooting parameter δov. A decrease in α or increase in Z or δov leads to a movement of the SRC peak towards a lower frequency. The change in Z and α only slightly affects the value of MHeF, but the variation in δov can affect the value of MHeF significantly. Thus the SRC peak might aid in determining the value of MHeF and calibrating δov. In addition, the effects of convective acceleration of SRC stars and the decrease in the νmax of ‘semidegenerate’ stars with mass result in the appearance of a shoulder between about 40 and 50 μHz in the νmax distribution. However, the convective acceleration of stars with M MHeF is obviously larger than that for populations with M < MHeF.
KINEMATICS OF PLANETARY NEBULAE IN THE OUTSKIRTS OF THE ELLIPTICAL GALAXY NGC 4697

We describe the implementation of slitless radial velocity measurements of extragalactic planetary nebulae (PNs) with the 8.2 m Subaru telescope and its Cassegrain imaging spectrograph, Faint Object Camera and Spectrograph (FOCAS). As a first application, we have extended a previous search for PNs in NGC 4697 to larger angular distances from its center. A total of 218 PNs were detected, and their radial velocities were measured. We have added 56 new PN detections to the existing sample of 535, observed previously with the ESO VLT + FORS imaging spectrograph; 36 of these new 56 PNs are located at angular distances larger than 230 arcsec from the center of NGC 4697. We compare the new FOCAS velocities with the earlier FORS velocities, for 158 of the 162 reobserved sources, finding good agreement. We now have kinematic information extending out to five effective radii from the center. The outer line-of-sight velocity dispersion is a bit lower than estimated earlier. This result is compatible with the existence of a dark matter halo plus some degree of radial anisotropy, but the dark matter halo is rather inconspicuous, and it is still unclear how massive it can be. A more detailed global dynamical study of the whole set of PN velocities will be required to decide if they permit to narrow down the range of possible dark matter distributions in NGC 4697. The new radial velocities reveal no evidence of rotation at five effective radii.
Resistance matrix of a weighted graph

In contrast to the classical notion of distance as the length of a shortest path between two vertices, the concept of resistance distance, introduced by Klein and Randic, arises naturally from several different considerations and is more amenable, to mathematical treatment. For a connected graph with n vertices, the resistance matrix of the graph is defined to be the n × n matrix with its (i, j)-entry equal to the resistance distance between the i-th and the j-th vertices. We obtain a formula for the inverse and the determinant of the resistance matrix of a weighted graph, thereby generalizing some earlier work, including that of Graham, Pollack, Lova'sz, Xiao and Gutman.
Performance analysis of professional U-23 portuguese players in small-sided games

The aim of this study was to examine the influence of different small-sided games (SSGs) format on external, internal load and technical actions of professional U-23 portuguese soccer players. Eight players (20.1±0.8 years, 180.4±7.2 cm, 75.9±4.9 kg) performed three different 4 vs. 4 ball possession SSGs (3x3 min play/rest) in different pitch dimensions, SSG1 16x24 m, SSG2 20x30 m and SSG3 24x36 m. All SSGs were video recorded for technical actions analysis. WIMU PROTM (RealTrack Systems, Almeria, Spain) inertial devices were used for internal and external load data collection. The distribution normality was determined with the Shapiro-Wilk test. Parametric and nonparametric statistics were selected accordingly. Statistical Package for the Social Sciences (SPSS™ 25.0 version) was used for data analysis. No significant differences were observed comparing the different SSGs in total distance covered, acceleration/deceleration distance, as well as in maximal and mean heart rate. Regarding the technical actions, no significant differences were observed in successful passes, contrary to the observed from SSG1 to SSG3 in duels (7.00±2.13; 4.38±2.44; 4.25±1.98), number of balls lost (2.63±1.30; 1.00±0.53; 0.88±1.12) and in between SSGs in high-speed running (p<0.05, ES=0.37). In senior and professional soccer players, the modification of the pitch size between 16x24 m and 24x36 m during 4 vs. 4 ball possession SSGs with 3x3 min play/rest promotes modifications in the dynamic of technical actions and internal and external training load variables Keywords: Small-sided games, Professional soccer, Technical actions, External and internal load, Performance.
Variance of the Time to Recruitment in an Organization with Two Grades

In this paper, a two grade organization subjected to random exit of personal due to policy decisions taken by the organization is considered. There is an associated loss of manpower if a person quits. As the exit of personnel is unpredictable, a new recruitment policy involving two thresholds for each grade-one is optional and the other mandatory is suggested to enable the organization to plan its decision on recruitment. Based on shock model approach two mathematical models are constructed using an appropriate univariate policy of recruitment. Performance measures namely mean and variance of the time to recruitment are obtained for both the models when (i) the loss of manhours process forms a sequence of independent and identically distributed exponential random variables (ii) the inter-decision times are independent and identically distributed exponential random variables and (iii) the optional and mandatory thresholds are exponential random variables. The analytical results are substantiated by numerical illustrations and the influence of nodal parameters on the performance measures is also analyzed.
Effect of Black Cumin Cake Addition on the Chemical Composition, Glycemic Index, Antioxidant Activity, and Cooking Quality of Durum Wheat Pasta

Pasta is a good carrier for plant enrichment substances due to its popularity among consumers. The purpose of the study was to investigate the functional potential and optimize the recipe of pasta made from durum semolina with the addition of black cumin cake at the level of 5, 10, 15, 20, and 25%. The use of black cumin cake resulted in a statistically significant (p ≤ 0.05) increase in the content of protein, fat, ash, and fiber, including both the insoluble and soluble fractions. A reduction in the digestible carbohydrate content, in vitro starch hydrolysis index (HI), was observed. Pasta with a reduced glycemic index (GI) compared to the semolina control was obtained. The content of polyphenols, including flavonoids, in the cake-enriched pasta increased significantly (p ≤ 0.05), which resulted in higher antioxidant activity against DPPH. The increase in the iron content was over 2.5 times higher in the sample with the 25% addition of black cumin cake than in the control sample. The functional addition significantly (p ≤ 0.05) increased the loss of dry matter and influenced the cooking time of pasta.
Effect of Al2O3 on Nanostructure and Ion Transport Properties of PVA/PEG/SSA Polymer Electrolyte Membrane

Polymer electrolyte membrane (PEM) fuel cells have the potential to reduce our energy consumption, pollutant emissions, and dependence on fossil fuels. To achieve a wide range of commercial PEMs, many efforts have been made to create novel polymer-based materials that can transport protons under anhydrous conditions. In this study, cross-linked poly(vinyl) alcohol (PVA)/poly(ethylene) glycol (PEG) membranes with varying alumina (Al2O3) content were synthesized using the solvent solution method. Wide-angle X-ray diffraction (XRD), water uptake, ion exchange capacity (IEC), and proton conductivity were then used to characterize the membranes. XRD results showed that the concentration of Al2O3 affected the degree of crystallinity of the membranes, with 0.7 wt. % Al2O3 providing the lowest crystallinity. Water uptake was discovered to be dependent not only on the Al2O3 group concentration (SSA content) but also on SSA, which influenced the hole volume size in the membranes. The ionic conductivity measurements provided that the samples were increased by SSA to a high value (0.13 S/m) at 0.7 wt. % Al2O3. Furthermore, the ionic conductivity of polymers devoid of SSA tended to increase as the Al2O3 concentration increased. The positron annihilation lifetimes revealed that as the Al2O3 concentration increased, the hole volume content of the polymer without SSA also increased. However, it was densified with SSA for the membrane. According to the findings of the study, PVA/PEG/SSA/0.7 wt. % Al2O3 might be employed as a PEM with high proton conductivity for fuel cell applications.
Gravitational microlensing as a probe for dark matter clumps

Extended dark matter (DM) substructures may play the role of microlenses in the Milky Way and in extragalactic gravitational lens systems (GLSs). We compare microlensing effects caused by point masses (Schwarzschild lenses) and extended clumps of matter using a simple model for the lens mapping. A superposition of the point mass and the extended clump is also considered. For special choices of the parameters, this model may represent a cusped clump of cold DM, a cored clump of self-interacting dark matter (SIDM) or an ultra compact minihalo of DM surrounding a massive point-like object. We built the resulting micro-amplification curves for various parameters of one clump moving with respect to the source in order to estimate differences between the light curves caused by clumps and by point lenses. The results show that it may be difficult to distinguish between these models. However, some region of the clump parameters can be restricted by considering the high amplification events at the present level of photometric accuracy. Then we estimate the statistical properties of the amplification curves in extragalactic GLSs. For this purpose, an ensemble of amplification curves is generated yielding the autocorrelation functions (ACFs) of the curves for different choices of the system parameters. We find that there can be a significant difference between these ACFs if the clump size is comparable with typical Einstein radii; as a rule, the contribution of clumps makes the ACFs less steep.
Maintaining Ecosystem and Economic Structure in a Three-Species Dynamical System in Chesapeake Bay

We consider a three-species fish dynamical system in Chesapeake Bay consisting of the Atlantic menhaden as the prey and its two competing predators, the striped bass and the catfish. Building on our previous work in this system, we consider the issue of balancing economic harvesting goals (financial gain for fishermen) with ecological harvesting goals (non-extinction of species). In particular, we investigate the bionomic equilibria, maximum sustainable yield, and the maximum economic yield. Analytical computations and numerical simulations are employed to provide some mathematical guidance on fisheries management policies.
Morphogenetic Response of Assorted Rice Genotypes to Salinity in Tanzania

Salinity, where salts concentrate on the soil surface causing severe decline of crop yields, is a worldwide problem. In Tanzania salinity is one of the major soil degradation challenges affecting over 3.5 million hectares limiting agriculture productivity of various crops including rice. Most of the varieties grown are sensitive to salts and inadequate tolerant cultivars available in the country. A hydroponics mass screening technique using Yoshinda Solution was used to test the 102 genotypes in NaCl- saline treated and non-treated solution at Tanzania Agricultural Research Institute (TARI-Dakawa Centre). Different salt concentrations (4 dSm-1, 6 dSm-1, 8 dSm-1 and 10 dSm) were used and the experiment was done in three replications. The genotypic variability for salinity tolerance was observed as less salt injury symptoms, low Na+ accumulation and Na+/K+ ratio in plant tissues and high biomass accumulation (fresh weight and dry weight). Results revealed further those 28 genotypes (28.45%) out of 102 showed tolerance to salinity, at high salinity level of 10dSm-1. Lines namely SR35266-2-18-2-1, SR35250-1-19-1-1, SR23364-128-1762-1-HV-1-1, SR35230-1-12-1-1, SR23364-128-1986-1-HV-1-1, SR34590-HB3433-4-1-1, SR35266-2-7-1-1, PBR1000922-1 and SR34053 (#5-52)-1-4-2-10-3-3 showed high performance under high salt conditions. Others includes SR35266-3-1-5-1, SR34574-2-10-3-1-2-1, SR35278-2-10-1-1, SR35250-2-3-1-1, SR35266-3-2-3-1, SR35266-3-2-4-1, SR23364-133-184-1-HV-1-1, SR34592-HB-1-HV-1, and SR34042F3-22-1-1-5-3 indicated tolerance to salt and had high dry matter as well. All the genotypes had increased levels of Na+ and differential performance was observed in some genotypes under saline and non-saline conditions. Among these three lines namely SR35266-2-7-1-1, SR23364-128-1762-1-HV-1-1, and SR34590- HB3433-4-1-1expressed high dilution ability as the K+ and Na+ concentrations were lower compared to other genotypes. The study, therefore, suggests that the lines can be used in breeding programs to develop varieties with potential to salt tolerance and other traits.
Scrape-off layer turbulence in TCV: evidence in support of stochastic modelling

Intermittent fluctuations in the TCV scrape-off layer have been investigated by analysing long Langmuir probe data time series under stationary conditions, allowing calculation of fluctuation statistics with high accuracy. The ion saturation current signal is dominated by the frequent occurrence of large-amplitude bursts attributed to filament structures moving through the scrape-off layer. The average burst shape is well described by a double-exponential wave-form with constant duration, while the waiting times and peak amplitudes of the bursts both have an exponential distribution. Associated with bursts in the ion saturation current is a dipole-shaped floating potential structure and radially outwards directed electric drift velocity and particle flux, with average peak values increasing with the saturation current burst amplitude. The floating potential fluctuations have a normal probability density function while the distributions for the ion saturation current and estimated radial velocity have exponential tails for large fluctuations. These findings are discussed in the light of prevailing theories for filament motion and a stochastic model for intermittent scrape-off layer plasma fluctuations.
Dynamical Evolution of Outer-Halo Globular Clusters

Abstract Outer-halo globular clusters show large half-light radii and flat stellar mass functions, depleted in low-mass stars. Using N-body simulations of globular clusters on eccentric orbits within a Milky Way-like potential, we show how a cluster’s half-mass radius and its mass function develop over time. The slope of the central mass function flattens proportionally to the amount of mass a cluster has lost, and the half-mass radius grows to a size proportional to the average strength of the tidal field. The main driver of these processes is mass segregation of dark remnants. We conclude that the extended, depleted clusters observed in the Milky Way must have had small half-mass radii in the past, and that they expanded due to the weak tidal field they spend most of their lifetime in. Moreover, their mass functions must have been steeper in the past but flattened significantly as a cause of mass segregation and tidal mass loss.