Estimation of the Hydrodynamic Parameters of Soils Subjected to Water Scarcity: Application of BEST and Introduction of a Specific Methodology

Propose a specific method (Junction Between Arya and Heitman and Haverkamp - JAHH), similar to BEST, to obtain the hydrodynamic parameters of soils in Pernambuco, Brazil. Sample: Department of Civil Engineering, Polytechnic School of Pernambuco – POLI, between March 2019 and February 2021. For this, BEST and JAHH were used to obtain the hydrodynamic characteristics of the collected materials, and the results of both methods were compared with simulations performed in Hydrus-1D. Sorptivity and Ks, acquired using both methods, presented differences reached 68.38% regarding Ks. The characteristic radius of the pores (λm) and capillary length (λc) obtained with BEST are not coherent, and this can be explained because during the evaluation of one sandy soil, λm values were the highest and λc were the lowest, when the opposite was expected. The use of JAHH to estimate soil parameters could generate more coherent estimates than BEST-slope, even though both of them have presented results of the same proportion, such as sorptivity and saturated hydraulic conductivity, for exemple. Therefore, the proposed method presented more pertinent results when compared to BEST regarding the studied soils.

The statistical properties of protostellar discs and their dependence on metallicity

We present the analysis of the properties of large samples of protostellar discs formed in four radiation hydrodynamical simulations of star cluster formation. The four calculations have metallicities of 0.01, 0.1, 1 and 3 times solar metallicity. The calculations treat dust and gas temperatures separately and include a thermochemical model of the diffuse interstellar medium. We find the radii of discs of bound protostellar systems tend to decrease with decreasing metallicity, with the median characteristic radius of discs in the 0.01 and 3 times solar metallicity calculations being ≈20 and ≈65 au, respectively. Disc masses and radii of isolated protostars also tend to decrease with decreasing metallicity. We find that the circumstellar discs and orbits of bound protostellar pairs, and the two spins of the two protostars are all less well aligned with each other with lower metallicity than with higher metallicity. These variations with metallicity are due to increased small scale fragmentation due to lower opacities and greater cooling rates with lower metallicity, which increase the stellar multiplicity and increase dynamical interactions. We compare the disc masses and radii of protostellar systems from the solar metallicity calculation with recent surveys of discs around Class 0 and I objects in the Orion and Perseus star-forming regions. The masses and radii of the simulated discs have similar distributions to the observed Class 0 and I discs.

The swampland at large number of space-time dimensions

We discuss some aspects of swampland constraints — especially the swamp-land distance conjecture — in a large number of space-time dimensions D. We analyze Kaluza-Klein (KK) states at large D and find that some KK spectra possess an interesting dependence on D. On the basis of these observations we propose a new large dimension conjecture. We apply it to KK states of compactifications to anti-de Sitter backgrounds where it predicts an upper bound on the dimension of space-time as a function of its characteristic radius. We also apply our conjecture to black hole spacetimes, whose entropies have a D-dependence very similar to that of the KK spectrum.

The Umov effect in cosmic dust analogue fluffy aggregates

ABSTRACT We investigate the effect of porosity in the Umov effect for the first time using the aggregate dust model. The Umov effect is an inverse correlation between the reflectivity (or geometric albedo) of an object and the degree of linear polarization of light scattered by it. Three different types of fractal aggregates: ballistic agglomeration (BA), ballistic agglomeration with one migration (BAM1), and ballistic agglomeration with two migrations (BAM2) having porosities 0.87, 0.74, and 0.64, respectively (which have the same characteristic radius ∼1 μm), are considered in our simulations. Using the multisphere T-matrix (mstm) code, maximum positive polarization (Pmax) and geometric albedo (A) are calculated for three different fractal aggregated structures considering amorphous silicate composition. Then Pmax and A are plotted against each other in logarithmic scale that shows a linear inverse correlation and a strong porosity dependence. This study shows that the porosity of the aggregates plays a crucial role in the Umov-law diagram. Further, we explore the effect of aggregate size parameter and the effect of composition in the Umov diagram for particles larger than the wavelength of incident radiation. A systematic study is presented in this paper.

Mathematical modeling diffusion of admixture particles in a strip with randomly located spherical inclusions of different materials with commensurable volume fractions of phases

The process of diffusion of admixture particles in a multiphase randomly nonhomogeneous body with spherical inclusions of different materials with commensurable volume fractions of phases is investigated. According to the theory of binary systems, a mathematical model of admixture diffusion in a multiphase body with spherical randomly disposed inclusions of different radii is constructed. The dense packing of spheres with different radii is used to modeling the skeleton of the body. The contact initial-boundary value problem is reduced to the mass transfer equation for the whole body. Its solution is constructed in the form of Neumann series. On the basis of the obtained calculation formula, a quantitative analysis of the mass transfer of admixture in the body with spherical inclusions, which are filled with materials of fundamentally different physical nature, but commensurable volume fractions, is carried out. It is shown that in modeling skeleton by spheres of one characteristic radius averaged concentration values coincide for different cases of radius, such as when characteristic radius equals to the average value of the radii of inclusions; or to the radius corresponding the smallest spherical inclusion; or to the radius of an order of magnitude smaller than this value.

Effects of environment on stellar metallicity profiles of late-type galaxies in the CALIFA survey

Aims. We explore the effects of environment in the evolution of late-type galaxies by studying the radial profiles of light- and mass-weighted metallicities of galaxies in two discrete environments: field and groups. Methods. We used a sample of 167 late-type galaxies with stellar masses of 9 ≤ log(M⋆/M⊙) ≤ 12 drawn from the Calar Alto Legacy Integral Field Area (CALIFA) survey. Firstly, we obtained light- and mass-weighted stellar metallicity profiles and stellar mass density profiles of these galaxies using publicly available data. We then classified them according to their environment into field and group galaxies. Finally, we studied the metallicity of galaxies in these two environments, including a comparison of the metallicity as a function of radius, at a characteristic scale, and as a function of stellar mass surface density. As metallicity depends on galaxy mass, we took special care throughout the study to compare, in all cases, subsamples of galaxies in groups and in the field that have similar masses. Results. We find significant differences between group and field late-type galaxies in terms of their metallicity: group galaxies are systematically higher in metallicity than their field counterparts. We find that field galaxies, in general, have metallicity profiles that show a negative gradient in their inner regions and a shallower profile at larger radii. This is in contrast to the metallicity profiles of galaxies in groups, which tend to be flat in the inner regions and to have a negative gradient in the outer parts. Regarding the metallicity at the characteristic radius of the luminosity profiles, we consistently find that it is higher for group galaxies irrespective of galaxy mass. At fixed local stellar surface mass density, group galaxies are again higher in metallicity, also the dependence of metallicity on surface density is less important for group galaxies. Conclusions. The evidence of a clear difference in metallicity between group and field galaxies as a function of mass, spatial scale, and local stellar mass density is indicative of the different evolutionary paths followed by galaxies in groups and in the field. We discuss some possible implications of the observed differences.

Accurate mass estimates from the proper motions of dispersion-supported galaxies

ABSTRACT We derive a new mass estimator that relies on internal proper motion measurements of dispersion-supported stellar systems, one that is distinct and complementary to existing estimators for line-of-sight velocities. Starting with the spherical Jeans equation, we show that there exists a radius where the mass enclosed depends only on the projected tangential velocity dispersion, assuming that the anisotropy profile slowly varies. This is well-approximated at the radius where the log-slope of the stellar tracer profile is −2: r−2. The associated mass is $M(r_{-2}) = 2 G^{-1} \langle \sigma _{\mathcal {T}}^{2}\rangle ^{*} r_{-2}$ and the circular velocity is $V^{2}({r_{-2}}) = 2\langle \sigma _{\mathcal {T}}^{2}\rangle ^{*}$. For a Plummer profile r−2 ≃ 4Re/5. Importantly, r−2 is smaller than the characteristic radius for line-of-sight velocities derived by Wolf et al. Together, the two estimators can constrain the mass profiles of dispersion-supported galaxies. We illustrate its applicability using published proper motion measurements of dwarf galaxies Draco and Sculptor, and find that they are consistent with inhabiting cuspy NFW subhaloes of the kind predicted in CDM but we cannot rule out a core. We test our combined mass estimators against previously published, non-spherical cosmological dwarf galaxy simulations done in both cold dark matter (CDM; naturally cuspy profile) and self-interacting dark matter (SIDM; cored profile). For CDM, the estimates for the dynamic rotation curves are found to be accurate to $10\rm { per\, cent}$ while SIDM are accurate to $15\rm { per\, cent}$. Unfortunately, this level of accuracy is not good enough to measure slopes at the level required to distinguish between cusps and cores of the type predicted in viable SIDM models without stronger priors. However, we find that this provides good enough accuracy to distinguish between the normalization differences predicted at small radii (r ≃ r−2 < rcore) for interesting SIDM models. As the number of galaxies with internal proper motions increases, mass estimators of this kind will enable valuable constraints on SIDM and CDM models.

Renormalized quantum stress–energy tensor for massive spinor fields around global monopoles

The renormalized quantum stress–energy tensor [Formula: see text] for a massive spinor field around global monopoles is constructed within the framework of Schwinger–DeWitt approximation, valid whenever the Compton length of the quantum field is much less than the characteristic radius of the curvature of the background geometry. The results obtained show that the quantum massive spinor field in the global monopole spacetime violates all the pointwise energy conditions.

A catalogue of open cluster radii determined from Gaia proper motions

ABSTRACT In this work, we improve a previously published method to calculate in a reliable way the radius of an open cluster (OC). The method is based on the behaviour of stars in the proper motion space as the sampling changes in the position space. Here, we describe the new version of the method and show its performance and robustness. Additionally, we apply it to a large number of OCs using data from Gaia second data release to generate a catalogue of 401 clusters with reliable radius estimations. The range of obtained apparent radii goes from Rc = 1.4 ± 0.1 arcmin (for the cluster FSR 1651) to Rc = 25.5 ± 3.5 arcmin (for NGC 2437). Cluster linear sizes follow very closely a lognormal distribution with a mean characteristic radius of Rc = 3.7 pc, and its high radius tail can be fitted by a power law as $N \propto R_c^{-3.11\pm 0.35}$. Additionally, we find that number of members, cluster radius, and age follow the relationship $N_c \propto R_c^{1.2\pm 0.1} \cdot T_c^{-1.9\pm 0.4}$ where the younger and more extensive the cluster, the more members it presents. The proposed method is not sensitive to low density or irregular spatial distributions of stars and, therefore, is a good alternative or complementary procedure to calculate OC radii not having previous information on star memberships.

The new fundamental plane dictating galaxy cluster evolution

In this study, we show that the characteristic radius rs, mass Ms, and the X-ray temperature, TX, of galaxy clusters form a thin plane in the space of (log rs, log Ms, log TX). This tight correlation indicates that the cluster structure including the temperature is affected by the formation time of individual clusters. Numerical simulations show that clusters move along the fundamental plane as they evolve. The plane and the cluster evolution within the plane can be explained by a similarity solution of structure formation. The angle of the plane shows that clusters have not achieved “virial equilibrium”. The details of this study are written in Fujita et al. (2018a,b).