Physical Sciences Forum

In this investigation, an artificial-neural-network-based mathematical model was developed for the prediction of nickel adsorption data. As input variables, the initial concentration, adsorbent dosage, and pH of the nickel solution were chosen, while the removal efficiency was chosen as an output variable. The hyperparameters were optimized to determine the perfect topology for the model. The study demonstrated that the 3-2-1 ANN architecture was the most suitable topology. The determination coefficient of 0.98 and the mean squared error of 0.02 indicated the high performance of the developed model, which was successfully applied for isotherm data prediction. Full article

This study considers dualistic structures of the probability simplex from the information geometry perspective. We investigate a foliation by deformed probability simplexes for the transition of $\alpha$-parameters, not for a fixed $\alpha$-parameter. We also describe the properties of extended divergences on the foliation when different $\alpha$-parameters are defined on each of the various leaves. Full article

This work deals with a numerical study of the different thermal processes in a gold nanoparticle heated with a femtosecond pulse laser and cooled in different biological tissues, such as healthy human prostate, blood, fat, tumor prostate, skin and protein myoglobin. A 40 nm diameter gold nanoparticle is heated using a femtosecond pulse laser with a duration of 85 fs and a fluence of 1.4 J/m². A two-temperature model is used to describe the dynamics of the exchange of energy between the electron gas and the phononic lattice in addition to Fourier’s law and the relationship between the thermal conductivity of the external medium and the temperature. The temperature of the external medium near the nanoparticle surface was computed, and the effect of the laser energy was reported. Full article

The Atacama Large Millimeter/submillimeter Array (ALMA) is currently revolutionizing observational astrophysics. The aperture synthesis technique provides angular resolution otherwise unachievable with the conventional single-aperture telescope. However, recovering the image from inherently undersampled data is a challenging task. The clean algorithm has proven successful and reliable and is commonly used in imaging interferometric observations. It is not, however, free of limitations. Point-source assumption, central to the clean is not optimal for the extended structures of molecular gas recovered by ALMA. Additionally, negative fluxes recovered with clean are not physical. This begs the search for alternatives that would be better suited for specific scientific cases. We present recent developments in imaging ALMA data using Bayesian inference techniques, namely the resolve algorithm. This algorithm, based on information field theory, has already been successfully applied to image the Very Large Array data. We compare the capability of both clean and resolve to recover known sky signal, convoluted with the simulator of ALMA observation data, and we investigate the problem with a set of actual ALMA observations. Full article

We present a method for improving the performance of nested sampling as well as its accuracy. Building on previous work we show that posterior repartitioning may be used to reduce the amount of time nested sampling spends in compressing from prior to posterior if a suitable “proposal” distribution is supplied. We showcase this on a cosmological example with a Gaussian posterior, and release the code as an LGPL licensed, extensible Python package supernest. Full article

Black Holes are not expected to form in the mass range of 60 M_⊙ to 130 M_⊙ because of the Pair-Instability Supernova (PISN). However, the recent observational evidence of GW190521 does not comply with the existing theory. Here, we have looked into the effects of Dark Matter (DM) in the progenitors of PISN in terms of luminosity, lifetime and temperature and have shown that in the presence of DM particles, the progenitors can overcome the PISN stage to collapse into a black hole (BH) as a remnant. Full article

Analytical spherically symmetric static solution to the set of Einstein and Klein-Gordon equations in a synchronous reference frame is considered. In a synchronous reference frame, a static solution exists in the ultrarelativistic limit $p=-\epsilon /3$. Pressure p is negative when matter tends to contract. The solution pretends to describe a collapsed black hole. The balance at the boundary with dark matter ensures the static solution for a black hole. There is a spherical layer inside a black hole between two “gravitational” radii $r_g$ and $r_h>r_g$, where the solution exists, but it is not unique. In a synchronous reference frame, $\det g_{ik}$ and $g^{rr}$ do not change signs. The non-uniqueness of solutions with boundary conditions at $r=r_g$ and $r=r_h$ makes it possible to find the gravitational field both inside and outside a black hole. The synchronous reference frame allows one to find the remaining mass of the condensate. In the model “$\lambda {\left|\psi \right|}^4$”, total mass $M=3\left(c^2/2k\right)\hspace{0.17em}{r}_h$ is three times that of what a distant observer sees. This gravitational mass defect is spent for bosons to be in the bound ground state, and for the balance between elasticity and density of the condensate. Full article

Large inconsistencies in the outcome of precise measurements of Newtonian gravitational ‘constant’ were identified throughout more than three hundred experiments conducted up to date. This paper illustrates the dependency of the Newtonian gravitational parameter on the curvature of the background and the associated field strength of vacuum energy. Additionally, the derived interaction field equations show that boundary interactions and spin-spin correlations of vacuum and conventional energy densities contribute to the emergence of mass. Experimental conditions are recommended to achieve consistent outcomes of the parameter precision measurements, which can directly falsify or provide confirmations to the presented field equations. Full article

Advances in cosmology and astronomical observations have brought to light significant tensions and uncertainties within the current model of cosmology, which assumes a spatially flat Universe and is known as the ΛCDM model. Moreover, the Planck Legacy 2018 release has preferred that the early Universe had a positive curvature with a confidence level more than 99%. This study reports a quantum mechanism that could potentially replace the concept of dark matter/energy by taking into the account the primordial curvature while generating the present-day spatial flatness. The approach incorporates the primordial curvature as the background curvature to extend the field equations into brane-world gravity. It utilizes a new wavefunction of the Universe that propagates in the bulk with respect to the scale factor and curvature radius of the early Universe upon the emission of the cosmic microwave background. The resulting wavefunction yields both positive and negative solutions, revealing the presence of a pair of entangled wavefunctions as a manifestation of the creation of matter and antimatter sides of the Universe. The wavefunction shows a nascent hyperbolic expansion away from early energy in opposite directions followed by a first decelerating expansion phase during the first ~10 Gyr and a subsequent accelerating expansion phase in reverse directions. During the second phase, both Universe sides are free-falling towards each other under gravitational acceleration. The simulation of the predicted background curvature evolution shows that the early curved background caused galaxies to experience external fields, resulting in the fast orbital speed of outer stars. Finally, the wavefunction predicts that the Universe will eventually undergo a rapid contraction phase resulting in a Big Crunch, which reveals a cyclic Universe. Full article

In a recent paper, a new conformally flat metric was introduced, describing an expanding scalar field in a spherically symmetric geometry. The spacetime can be interpreted as a Schwarzschild-like model with an apparent horizon surrounding the curvature singularity. For the above metric, we present the complete conformal Lie algebra consisting of a six-dimensional subalgebra of isometries (Killing Vector Fields or KVFs) and nine proper conformal vector fields (CVFs). An interesting aspect of our findings is that there exists a gradient (proper) conformal symmetry (i.e., its bivector F_ab vanishes) which verifies the importance of gradient symmetries in constructing viable cosmological models. In addition, the 9-dimensional conformal algebra implies the existence of constants of motion along null geodesics that allow us to determine the complete solution of null geodesic equations. Full article

It has recently been shown that the tunneling wavefunction proposal is consistent with loop quantum geometry corrections, including both holonomy and inverse scale factor corrections, in the gravitational part of a spatially closed isotropic model with a positive cosmological constant. However, in the presence of inflationary potential, the initial singularity is kinetic-dominated, and the effective minisuperspace potential again diverges at the zero scale factor. As the wavefunction in loop quantum cosmology cannot increase towards the zero scale factor, the tunneling wavefunction seems incompatible. We show that consistently including inverse scale factor modifications, in scalar field Hamiltonian, changes the effective potential into a barrier potential, allowing the tunneling proposal. We also discuss the potential quantum instability of the cyclic universe, resulting from tunneling. Full article

This paper shows that the field defined by the Wheeler–DeWitt equation for pure gravity is neither a standard gravitational field nor the field representing a particular universe. The theory offers a unified description of geometry and matter, with geometry being fundamental. The quantum theory possesses gravitational decoherence when the signature of $R^{\left(3\right)}$ changes. The quantum theory resolves singularities dynamically. Application to the FLRW $\kappa =0$ shows the creation of local geometries during quantum evolution. The 3-metric is modified near the classical singularity in the case of the Schwarzschild geometry. Full article

Galactic feedback (i.e., outflows) plays a fundamental role in regulating galaxy formation and evolution. We investigate the physical properties of galactic outflows in a sample of 29 local low-metallicity dwarf galaxies drawn from the Dwarf Galaxy Survey. We make use of Herschel/PACS archival data to detect outflows in the broad wings of observed [CII] 158 μm line profiles. We detect outflowing gas in 1/3 of the sample, and in the average galaxy population through line stacking. We find typical mass-loading factors (i.e., outflow efficiencies) of the order of unity. Outflow velocities are larger than the velocities required from gas to escape the gravitational potential of our targets, suggesting that a significant amount of gas and dust is brought out of their halos. Our results will be used as input for chemical models, posing new constraints on the processes of dust production/destruction in the interstellar medium of galaxies. Full article

Galaxies are thought to grow through star formation or by interacting with each other. To understand which process dominates, we investigated the contribution of major mergers to the galaxy mass assembly across cosmic time. We made use of recent observations from the ALPINE survey to analyze the morphology and kinematic information provided by the [CII] 158 $\mathsf{\mu }$m line observed in $z\sim 5$ star-forming galaxies. We found that 40% of galaxies in that epoch were undergoing merging. By combining our results with studies at lower redshift, we computed the cosmic evolution of the merger fraction, estimating that major mergers could contribute up to 30% to the cosmic star-formation rate density at $z>4$. Full article

The recent Planck Legacy 2018 release verified the presence of an enhanced lensing amplitude in the power spectra of the cosmic microwave background with a confidence level of over 99%, which implies that the early Universe had a positive curvature. In this study, the curvature of the early Universe is regarded as the curvature of 4D conformal bulk while celestial objects that induce a localized curvature in the bulk are considered as 4D relativistic cloud-worlds. Likewise, quantum fields are considered as 4D relativistic quantum clouds that are affected by the curvature of the bulk as a manifestation of gravity. This approach could eliminate the singularities and satisfy the conditions of a conformal invariance theory. Full article