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We explore the possibility of traversable wormhole formation in the dark matter halos in the context of f (Q) gravity. We obtain the exact wormhole solutions with anisotropic matter source based on the Bose–Einstein condensate, Navarro-Frenk-White, and pseudo-isothermal matter density profiles. Notably, we present a novel wormhole solution supported by these dark matters using the expressions for the density profile and rotational velocity along with the modified field equations to calculate the redshift and shape functions of the wormholes. With a particular set of parameters, we demonstrate that our proposed wormhole solutions fulfill the flare-out condition against an asymptotic background. Additionally, we examine the energy conditions (ECs), focusing on the null ECs at the wormhole's throat, providing a graphical representation of the feasible and negative regions. Our study also examines the wormhole's shadow in the presence of various dark matter models, revealing that higher central densities result in a shadow closer to the throat, whereas lower values have the opposite effect. Moreover, we explore the deflection of light when it encounters these wormholes, particularly noting that light deflection approaches infinity at the throat, where the gravitational field is extremely strong. [ABSTRACT FROM AUTHOR]

We consider some of the epistemic benefits of exploring "theory space" in the context of modifications of general relativity with intended applications in cosmology. We show how studying modifications of general relativity can help in assessing the robustness of empirical inferences, particularly in inaccessible regimes. We also discuss challenges to sharply distinguishing apparently distinct directions in theory space. [ABSTRACT FROM AUTHOR]

Teleparallel gravity, an empirically equivalent counterpart to general relativity, represents the influence of gravity using torsional forces. It raises questions about theory interpretation and underdetermination. To better understand the torsional forces of teleparallel gravity, we consider a context in which forces are better understood: classical spacetimes. We propose a method of incorporating torsion into the classical spacetime context that yields a classical theory of gravity with a closed temporal metric and spacetime torsion. We then prove a result analogous to the Trautman degeometrization theorem: that every model of Newton–Cartan theory gives rise, non-uniquely, to a model of this theory. [ABSTRACT FROM AUTHOR]

This paper presents a finite‐differences 3D numerical model that simulates the gravity and thermal structure of the Corsica‐Sardinia Block (CSB), an apparently stable lithospheric domain characterized by cryptic tectonic activity. In the experiments, we change the density and heat production rate of the model crust within a range of geologically realistic values to fit the measured Bouguer gravity anomaly and surface heat flow pattern. The discrepancy between the observed geophysical structure and the outcomes of numerical modelling are discussed in relation to the composition of the CSB crust and finally recast in the geodynamic framework of the western Mediterranean region. [ABSTRACT FROM AUTHOR]

Recent years have seen the development of multiple in silico lung models, notably with the aim of improving patient care for pulmonary diseases. These models vary in complexity and typically only consider the implementation of pleural pressure, a depression that keeps the lungs inflated. Gravity, often considered negligible compared to pleural pressure, has been largely overlooked, also due to the complexity of formulating physiological boundary conditions to counterbalance it. However, gravity is known to affect pulmonary functions, such as ventilation. In this study, we incorporated gravity into a recent lung poromechanical model. To do so, in addition to the gravitational body force, we proposed novel boundary conditions consisting in a heterogeneous pleural pressure field constrained to counterbalance gravity to reach global equilibrium of applied forces. We assessed the impact of gravity on the global and local behavior of the model, including the pressure–volume response and porosity field. Our findings reveal that gravity, despite being small, influences lung response. Specifically, the inclusion of gravity in our model led to the emergence of heterogeneities in deformation and stress distribution, compatible with in vivo imaging data. This could provide valuable insights for predicting the progression of certain pulmonary diseases by correlating areas subjected to higher deformation and stresses with disease evolution patterns. [ABSTRACT FROM AUTHOR]

This paper considers the case where multiple tariff schemes (e.g. general and preferential schemes) are available between trading countries. We incorporate these tariffs into gravity equations and estimate them by the Pseudo-Poisson maximum likelihood technique. The results show that omitting either tariff type leads to significant estimates biases. If fixed effects to control other tariffs are not included in the model, both preferential and general tariffs are to be introduced in the gravity equation. Indeed, some estimation results for precision metals show that reducing both types of tariffs contributes to significantly increasing trade values. However, reducing general tariffs does not always have a trade-enhancing effect. In leather products, for example, its impact was insignificant. Nevertheless, the reduction of preferential tariffs was again found to increase trade values significantly. [ABSTRACT FROM AUTHOR]

In this work, we have obtained new phantom fluid-type traversable wormhole (WH) solutions in the context of f (R , T) modified gravity. We investigate the potential that some equations of state (EoS), specifically phantom energy, which describes the accelerated expansion of the universe, could support the existence of traversable wormholes. This cosmic fluid thus offers us a plausible explanation for the occurrence of WH geometries. We construct two WH models with matter Lagrangian density L m = - (- ρ + P r + 2 P t) and inspect numerous characteristics of these models under the WH geometry. The first WH solution (WH-I) is discovered by utilising a linear barotropic equation of state (EoS) connected with phantom energy ω < - 1 indicating the presence of the phantom fluid and pointing to the Universe's expansion, while in the second WH (WH-II) solution, we take into account an interesting EoS ρ = η (P t - P r) to generate a WH model. Additionally, it showed that the phantom fluid WH-I solution violates the radial null energy condition (NEC) while tangential NEC is satisfied. On the other hand, for the WH-II solution, NEC is violated. Extensive detailed discussions of the matter components have been done via graphical analysis. The obtained WH geometries satisfy a stable WH's physically acceptable criteria. [ABSTRACT FROM AUTHOR]

To gain insight into the organization of the underlying structures in the northern Tunisia region, detailed gravity data in combination with geological information have been investigated. Many techniques have been used, including residual, upward continuations and derivative. Results from the edge detection technique based on the tilt angle map generated from the first vertical gradient were discussed and compared with results obtained by Euler deconvolution. The compilation and comparison of gravity maps and geology maps enable the determination of major structural trends. It validates specific structural elements acquired from outcrops and specifies new ones. According to the gravity data interpretation, the area of study is impacted by several underlying structural trends. The main trend direction is NE–SW, which is closely linked to the J Chehid and Bled Tejra Akseb trends. NW–SE direction is the second significant trend that borders Bled El Ghorfa to the north. Additional determined trends include: the N–S direction, which is associated with the Lakouat fault. A strong correlation was noted between results from tilt angle method and Euler deconvolution, showing that they may both be used to delineate the main structural framework of the region. [ABSTRACT FROM AUTHOR]

The processing of potential field datasets requires many steps; one of them is the inverse modeling of potential field data. Using a measurement dataset, the purpose is to evaluate the physical and geometric properties of an unidentified model in the subsurface. Because of the ill-posedness of the inverse problem, the determination of an acceptable solution requires the imposition of a regularization term to stabilize the inversion process. We also need a regularization parameter that determines the comparative weights of the stabilization and data fit terms. This work offers an evaluation of automated strategies for the estimation of the regularization parameter for underdetermined linear inverse problems. We look at the methods of generalized cross validation, active constraint balancing (ACB), the discrepancy principle, and the unbiased predictive risk estimator. It has been shown that the ACB technique is superior by applying the algorithms to both synthetic data and field data, which produces density models that are representative of real structures and demonstrate the method's supremacy. Data acquired over the chromite deposit in Camaguey, Cuba, are utilized to corroborate the procedures for the inversion of experimental data. The findings gathered from the three-dimensional inversion of gravity data from this region demonstrate that the ACB approach gives appropriate estimations of anomalous density structures and depth resolution inside the subsurface. [ABSTRACT FROM AUTHOR]

An isolated liquid slug in the pipeline can accelerate and achieve a high speed when subjected to a driving pressure. During the slug's high-speed movement in a pipeline, part of the liquid will shed from it resulting in changes in the slug's mass and length. To understand the mass shedding mechanism, the mass shedding rate is studied using three-dimensional computational-fluid-dynamics methodology, in which the volume-of-fluid technique is applied to track the water-air interface and the RNG k - ε model is used to describe the turbulence. The effects of driving pressure, initial slug length, pipe inclination angle, pipe wall roughness and gravity on the slug mass shedding rate are investigated. The results show that the slug mass shedding rate is independent of driving pressure, initial slug length, pipe inclination angle and gravity, and it increases as a power function with the increase in wall roughness. It is explained from the mass shedding rate that when the slug's traveled distance exceeds six times the initial slug length, the slug will break up. This paper solves the problem that there is no standard to select a reliable mass shedding rate for modeling the isolated high-speed slug propagating in pipelines. [ABSTRACT FROM AUTHOR]

This paper investigates the effects of hemispherical mounds on filmwise condensation heat transfer in micro-channels. Also investigated were the impacts that spatial orientation of the three-sided condensation surface (i.e., gravitational effects) on steam condensation, where the cooled surfaces were either the lower surface (i.e., gravity pulls liquid towards the condensing surfaces) or upper surface (i.e., gravity pulls liquid away from the condensing surfaces). Two test coupons were used with 1.9-mm hydraulic diameters and either a plain copper surface or a copper surface modified with 2-mm diameter hemispherical mounds. Heat transfer coefficients, film visualization, and pressure drop measurements were recorded for both coupons in both orientations at mass fluxes of 50 kg/m2s and 125 kg/m2s. For all test conditions, the mounds were found to increase condensation heat transfer coefficients by at minimum 13% and at maximum 79%. When the test section was inverted (i.e., condensing surface on the top of flowing steam), minimal differences were found in mound performance, while the plain coupon reduces heat transfer coefficients by as much as 14%. Flow visualization suggests that the mounds enhanced heat transfer due to the disruption of the film as well as by reducing the thermal resistance of the film. Pressure drops followed parabolic behavior with quality, being higher in the mound coupon than the plain coupon. No significant pressure drop differences in the inverted orientation were observed. [ABSTRACT FROM AUTHOR]

Recently, it was shown that if two distant test masses, each in a spatially superposed quantum state, become entangled due to their mutual gravitational interaction, then this entanglement could serve as evidence of the quantum nature of gravity. We extend this treatment to a many-body system in a general setup and study the entanglement properties of the time-evolved state. We exactly compute the time-dependent I-concurrence for every bipartition and obtain the necessary and sufficient condition for the creation of genuine many-body entanglement. We further show that this entanglement is of generalised GHZ type when certain conditions are met. We also evaluate the amount of multipartite entanglement in the system using a set of generalised Meyer-Wallach measures. [ABSTRACT FROM AUTHOR]

Under the influence of the sedimentation process, the phenomenon of intraformational non-homogeneity is widely observed in low-permeability reservoirs. In the development process of water and gas replacement (WAG), the transport law of water and gas and the distribution of residual oil are seriously affected by the non-homogeneity of reservoir properties. In this paper, a study on two types of reservoirs with certain lengths and thicknesses is carried out, and a reasonable development method is proposed according to the characteristics of each reservoir. Firstly, through indoor physical simulation experiments combined with low-field nuclear magnetic resonance scanning (NMR), this study investigates the influence of injection rate and core length on the double-layer low-permeability inhomogeneous core replacement and pore throat mobilization characteristics. Then, a two-layer inhomogeneous low-permeability microscopic model is designed to investigate the model's replacement and pore throat mobilization characteristics under the combined influence of rhythmites, gravity, the injection rate, etc. Finally, based on the results of the core replacement and numerical simulation, a more reasonable development method is proposed for each type of reservoir. The results show that for inhomogeneous cores of a certain length, the WAG process can significantly increase the injection pressure and effectively seal the high-permeability layer through the Jamin effect to improve the degree of recovery. Moreover, for positive and reverse rhythm reservoirs of a certain thickness, the injection rate can be reduced according to the physical properties of the reservoir, and the gravity overburden phenomenon of the gas is used to achieve the effective development of the upper layers. The effect of the development of a positive rhythm reservoir therefore improved significantly. These findings provide data support for improving the development effectiveness of CO2 in low-permeability inhomogeneous reservoirs and emphasize the importance of the influence of multiple factors, such as injection flow rate, gravity, and rhythm, in CO2 replacement. [ABSTRACT FROM AUTHOR]

In material handling, numerous solutions have been proposed to enhance the flexibility and adaptability of transport systems. Among these solutions, smart surfaces stand out as one of the most interesting responses, utilizing an array of actuators for common feeding tasks. The current paper focuses on a novel system within this category, notable for its distinguishing factor of being underactuated. With this characteristic, the concept leads to a simplified cost-effective design and a not actively driven functioning, leveraging gravity or object own velocity to manipulate the material flow maintaining top class performances, as the sorting rate reaches 4000 pcs/h. Specifically, the article begins with an introduction of the concept design and its digital model, followed by a description of the experimental setup built to test the surface's functionality and evaluate the predictions of the virtual counterpart. On top of that, a method to determine the essential parameters for the surface simulation is proposed and applied. As a result, the prototype successfully completed the three main intralogistic tasks experimented, i.e., sorting, slowing, and stopping of packages. Lastly, the digital model outcomes of the same operations were computed and compared with the measured results, demonstrating an accuracy of prediction with displacements and time errors below 7%. [ABSTRACT FROM AUTHOR]

In this paper, we have presented the cosmological model in Brans–Dicke theory (BDT) of gravity for a Bianchi type-IX spacetime. We obtained the exact solutions of the field equations by applying the new form of deceleration parameter, i.e. fractional linear varying deceleration parameter (FLVDP) as proposed by R. K. Mishra and A. Chand [Astrophys. Space Sci. 361, 1 (2016)]. In this paper, we have also presented the physical and geometric properties and mathematical analysis of the proposed model. Then we have provided the energy conditions and statefinder diagnostic. [ABSTRACT FROM AUTHOR]

We introduce a theoretical framework to alleviate the Hubble tension. This framework is based on dynamics of a minimally coupled scalar field which either belongs to the Brans–Dicke theory with a self-interacting potential or is the scalar partner of f(R) gravity. These two theories are dynamically equivalent when the Brans–Dicke parameter is zero. We will use the dynamical equivalence to interpret the Hubble tension in the same theoretical framework. For both theories, we write one set of field equations in which the value of a parameter distinguishes between the two theories. We will show that H0 actually evolves with redshift so that its value is consistent with that measured from the local distance ladder and then drops to the value measured from CMB at high redshift. We argue that even though both theories exhibit this behavior, Brans–Dicke theory with an exponential potential is more successful than power-law f(R) gravity to relieve the Hubble tension. [ABSTRACT FROM AUTHOR]

In this paper, we investigate a 4D solution of Einstein field equations, an extension of 2D Misner space in the context of Ricci-inverse (ℛℐ)-gravity theory. For that, we consider two different class, namely, Class-II model which is defined by the function f(ℛ,AμνAμν) and Class-III model defined by the function f(ℛ,풜,AμνAμν). Here, Aμν is the anti-curvature tensor with 풜 as its scalar, and ℛ is the Ricci scalar. Using this 4D metric as background, the modified field equations for Ricci-inverse gravity were derived and obtain the results. These derived field equations are then solvable by choosing the pure radiation field as the energy-momentum tensor, including a cosmological constant as does in the general relativity. This implies that the chosen 4D space-time is a valid solution in this novel gravity theory, and thereby violate the causality condition, analogous to general relativity. [ABSTRACT FROM AUTHOR]

In this paper, we explore a modified black brane within AdS space–time, characterized by the Lagrangian density 1qarcsin(qR)−2Λ. Due to the absence of an analytic solution, we approach the Einstein equations using a perturbative method, extending our analysis to the second order in q. Subsequently, we compute the ratio of shear viscosity to entropy density. Our results suggest that the KSS Bound is not saturated in this model. [ABSTRACT FROM AUTHOR]

Since the early 2000s, border walls and fences have proliferated and become a global phenomenon with about a third of the countries having at least one wall or fence along its borders. Taking proper account for endogeneity, phasing-in effects and reverse causality, our gravity model for the years 1990–2017 (118 countries) finds a stronger trade-reducing impact of physical border protection structures ranging from 59% to 72%. This impact of physical border protection measures is non-monotonic: the immediate walls effect is insignificant but over the first 4 years after the creation of a wall, it starts to slash trade flows strongly and significantly. [ABSTRACT FROM AUTHOR]

The Weyl potential, which is the sum of the spatial and temporal distortions of the Universe's geometry, provides a direct way of testing the theory of gravity and the validity of the ΛCDM (Lambda Cold Dark Matter) model. Here we present measurement of the Weyl potential at four redshifts bins using data from the first three years of observations of the Dark Energy Survey. We find that the measured Weyl potential is 2 σ, respectively 2.8 σ, below the ΛCDM predictions in the two lowest redshift bins. We show that these low values of the Weyl potential are at the origin of the tension between Cosmic Microwave Background measurements and weak lensing measurements, regarding the parameter σ8 which quantifies the clustering of matter. Interestingly, we find that the tension remains if no information from the Cosmic Microwave Background is used. Dark Energy Survey data on their own prefer a high value of the primordial fluctuations, together with a slow evolution of the Weyl potential. An important feature of our method is that the measurements of the Weyl potential are model-independent and can therefore be confronted with any theory of gravity, allowing efficient tests of models beyond General Relativity. The Weyl potential provides a direct way of testing the theory of gravity and the validity of the ΛCDM model. Here, the authors show Weyl potential measured at four redshifts bins and find that the measured values in the two lowest bins are in mild tension with the ΛCDM predictions. [ABSTRACT FROM AUTHOR]

Mimetic gravity has gained significant appeal in cosmological contexts, but static spherically symmetric space-times within the baseline theory are highly non-trivial: the two natural solutions are a naked singularity and a black hole space-time obtained through an appropriate gluing procedure. We study the shadow properties of these two objects, finding both to be pathological. In particular, the naked singularity does not cast a shadow, whereas the black hole casts a shadow which is too small. We argue that the Event Horizon Telescope images of M87 and Sgr A rule out the baseline version of mimetic gravity, preventing the theory from successfully accounting for the dark sector on cosmological scales. Our results highlight an interesting complementarity between black hole imaging observations and modified gravity theories of cosmological interest. [ABSTRACT FROM AUTHOR]

This study aims to examine the phenomenological consequences of the constant-roll condition on the f(R,ϕ,X) gravity in the context of a non-canonical scalar field. In this regard, two periods of inflation are investigated, specifically the slow-roll and quintessence phases, within the context of the non-canonical scalar field. We will make two assumptions: first, the slow-roll condition is imposed on the first slow-roll parameters, and second, the scalar field evolves according to the constant-roll condition. We provide a comprehensive explanation of the gravitational equations of motion that govern the behavior of the cosmological system. We consider the constant-roll condition and use a specifically chosen potential to simplify analytical calculations. By doing so, we express the slow-roll indices and the resulting observational indices of the theory as functions of the e-foldings number. Our analysis demonstrates that the existence of constant-roll inflation with non-canonical scalar fields aligns with observed results across a wide range of model parameters. Furthermore, we establish an equation that combines the fundamental equations of the theory. By using a differential operator, we convert this equation into a linear form, yielding the effective equation of state (EoS) parameter. The value of this parameter is dependent upon the exponential α parameter of the kinetic term, as well as to the first slow-roll parameter and the constant-roll parameter σ. Under the assumption of a fixed σ field, we demonstrate that the early universe has the ability to experience a two-stage inflation, as described by the EoS parameter. [ABSTRACT FROM AUTHOR]

The geodynamic evolution of the Liguro-Provençal Basin and its crust and upper mantle structure remain debated, especially regarding the role of rifting in continental break-up and seafloor spreading. Our study incorporates updated datasets, including new gravity maps from the AlpArray Gravity Working Group (complete Bouguer, free air, and isostatic anomalies) for 3D modeling and gravity field analysis, seismic data from Lobster offshore campaigns for direct comparison, and geodynamic models, supplemented by seismic profiles from previous French and Italian campaigns to constrain the interpretation. We used GFZ's IGMAS + software for interactive 3D modeling, creating a density model extending to 300 km depth that includes crustal and upper mantle inhomogeneities based on prior geodynamic models. This hybrid approach, with polygonal structures for the crust and voxels for the upper mantle, clarifies individual contributions to the gravity field. Extending initial gravity modeling from the SPP MB4D project INTEGRATE, our work provides a consistent 3D density model for the Alps and Ligurian Basin. The constrained 3D modeling and numerical analyses (terracing, clustering, filtering, curvature), along with vertical stress and gravitational potential energy calculations, suggest that rifting has significantly influenced the basin's geological evolution. [ABSTRACT FROM AUTHOR]

Gravity and electromagnetic interactions are the only fundamental physical interactions (outside the nuclear domain). In this work, we shall concentrate on Hamiltonians containing gravitational interaction, which according to general relativity must be retarded. In recent years, retarded gravity has explained many of the mysteries surrounding the "missing mass" related to galactic rotation curves, the Tully–Fisher relations, and gravitational lensing phenomena. Indeed, a recent paper analyzing 143 galaxies has demonstrated that retarded gravity will suffice to explain galaxies' rotation curves without the need to postulate dark matter for multiple types of galaxies. Moreover, it also demystified the "missing mass" related to galactic clusters and elliptic galaxies in which excess matter was derived through the virial theorem. Here, we give a mathematical criterion that specifies the cases in which retardation is important for gravity (and when it is not). The criterion takes the form of an inequality. [ABSTRACT FROM AUTHOR]

This study primarily focuses on exploring the nature of anisotropic spheres within the framework of extended symmetric teleparallel gravity. To accomplish this, an anisotropic matter distribution for f(Q,T)$f(Q,T)$ gravity model with Tolman–Kuchowicz spacetime is considered. Through this analysis, the necessary conditions for matching the interior and exterior geometries of the spheres are discussed and calculated the values of the unknown parameters involved. Furthermore, the physical properties of these spheres are analyzed using observational data from compact objects. The results demonstrate that the interior solutions obtained for anisotropic spheres fulfill all requisite physical criteria, thereby ensuring the stability of our model. [ABSTRACT FROM AUTHOR]

Astrogeodetic deflections of the vertical (DoVs) are close indicators of the slope of the geoid. Thus, DoVs observed along horizontal profiles may be integrated to create geoid undulation profiles. In this study, we collected DoV data in the Eastern Swiss Alps using a Swiss Digital Zenith Camera, the COmpact DIgital Astrometric Camera (CODIAC), and two total station-based QDaedalus systems. In the mountainous terrain of the Eastern Swiss Alps, the geoid profile was established at 15 benchmarks over a two-week period in June 2021. The elevation along the profile ranges from 1185 to 1800 m, with benchmark spacing ranging from 0.55 km to 2.10 km. The DoV, gravity, GNSS, and levelling measurements were conducted on these 15 benchmarks. The collected gravity data were primarily used for corrections of the DoV-based geoid profiles, accounting for variations in station height and the geoid-quasigeoid separation. The GNSS/levelling and DoV data were both used to compute geoid heights. These geoid heights are compared with the Swiss Geoid Model 2004 (CHGeo2004) and two global gravity field models (EGM2008 and XGM2019e). Our study demonstrates that absolute geoid heights derived from GNSS/leveling data achieve centimeter-level accuracy, underscoring the precision of this method. Comparisons with CHGeo2004 predictions reveal a strong correlation, closely aligning with both GNSS/leveling and DoV-derived results. Additionally, the differential geoid height analysis highlights localized variations in the geoid surface, further validating the robustness of CHGeo2004 in capturing fine-scale geoid heights. These findings confirm the reliability of both absolute and differential geoid height calculations for precise geoid modeling in complex mountainous terrains. [ABSTRACT FROM AUTHOR]

With the aim of correcting the problem of trajectory tracking control of a flexible joint space manipulator in environments with different gravity, a neural network adaptive inverse control algorithm based on singular perturbation theory is proposed to resist the disturbance caused by system uncertainty. Firstly, the dynamic model of a flexible joint space manipulator with the influence of gravity is established, and then the system is divided into a fast subsystem and a slow subsystem using singular perturbation theory. The velocity feedback control rate is designed for the fast subsystem to suppress the elastic vibration caused by the joint flexibility. For the slow subsystem, the uncertain term and known term are separated by the inverse control algorithm, where the uncertain term is approximated online by the RBF neural network, and the robust control rate is designed to compensate for the approximation error. The simulation results show that the control method can not only effectively reduce the high-frequency vibration caused by the flexible joint but also resist the system disturbance so that a good track control effect is achieved. [ABSTRACT FROM AUTHOR]

A spherically symmetric black hole solution in the conformal Weyl gravity was found by Mannheim and Kazanas in 1988. While the quasinormal modes (QNMs) of these black holes have been considered in a few works, here we complement these studies by considering in detail the regime of vanishing cosmological constant and negative values of the Weyl parameter for which we find quasinormal frequencies for scalar, Dirac and electromagnetic perturbations with the time-domain integration and WKB methods. In particular, we derive the compact and remarkably accurate analytic formula for the frequencies in the form of expansion in terms of the inverse multipole number. Comparison with the time-domain integration shows that the 6th order WKB method with the Padé approximants is quite accurate, unless the black hole is in the near extreme state. [ABSTRACT FROM AUTHOR]

In response to the unanswered relevant questions surrounding atherosclerosis, it becomes imperative to investigate arterioles using sophisticated mathematical modelling techniques to shed light on critical stress and strain patterns influenced by gravity. The primary objective of this study is to scrutinize flow characteristics and probe stress and strain distributions experienced by the intima layer of arterioles, encompassing coronary, renal, cerebral, mesenteric, and pulmonary arteries, under gravitational forces. This investigation employs a fluid-structure interaction methodology utilizing arbitrary Eulerian–Lagrangian formulation. The study delves into blood flow characteristics within coronary, renal, cerebral, mesenteric, and pulmonary arterioles using the fluid-structure interaction technique, employing an arbitrary Eulerian–Lagrangian formulation. It thoroughly examines various biomechanical parameters such as the Cauchy–Green stress tensor, Principal strain, Piola–Kirchoff stress tensor, deformation tensor, and volume strain along the intima layer under the gravitational influence, elucidating vulnerable regions prone to endothelial dysfunction. Higher values of δV are found at the left shoulder and in the intima's post stenosis area due to the pressure gradient along the flow channel, whereas other intima regions show a null volume strain. A thorough understanding of stress distribution is essential to create focused therapies to lessen vascular health problems. The stress in the post-stenosis region seems to affect the endothelial layer to a significant extent. [ABSTRACT FROM AUTHOR]

Motivated by the notion that the mathematics of gravity can be reproduced from a statistical requirement of maximal entropy, the consequences of introducing an entropic source term in the Einstein–Hilbert action are studied. For a spatially homogeneous cosmological system driven by this entropic source and enveloped by a time‐evolving apparent horizon, a modified version of the second law of thermodynamics is formulated. An explicit differential equation governing the internal entropy profile is found. Using a Hessian matrix analysis of the internal entropy, the author checked the thermodynamic stability for three categorically different toy models describing (i) a ΛCDM$\Lambda{\rm CDM}$ cosmology, (ii) a unified cosmic expanson, and (iii) a non‐singular ekpyrotic bounce. The mathematical condition for a second order phase transition during these evolutions from the divergence of specific heat at constant volume is found. The new‐found condition is purely kinematic and quadratic in nature, relating the deceleration parameter and the jerk parameter that chalks out an interesting curve on the parameter space. This condition is valid even without the entropic source term and may be treated as a general property of any phase transition. [ABSTRACT FROM AUTHOR]

Euler deconvolution is widely used as a semi-automatic interpretation technique for potential field data. In its original form it uses derivatives of orders 0 and 1, while second order Euler deconvolution uses derivatives of orders 0 and 2. Complete Euler deconvolution is introduced here, and this combines both methods to use derivatives of orders 0, 1, and 2. The use of the additional information in the three orders of derivatives provides increased accuracy compared to the original method, and when combined with other Euler equations it can also determine the structural index of the source. The methods are applied to both synthetic data and to two aeromagnetic data profiles from South Africa. [ABSTRACT FROM AUTHOR]

This study is based on the coupling of geological field data with geophysical studies in the geological mapping of the Central Domain of the Mbere Division (Adamawa-Cameroon). The first step was to calculate the residual grid associated with the geophysical data that will be used for the mapping of the basement. The second step before mapping consisted in calculating the analytical signal associated with the residual grid, used to interpret the geological formations under cover or in intrusion. Subsequently, a geological mapping approach based on the categorisation of geophysical signatures into ranges using the Encom Discover program was adopted. This approach is based on the analysis of the relief of geophysical anomalies. The process of categorisation which is done iteratively, takes into consideration in the same georeferenced space, the resolution of the input data, the variation of the field considered and the structural model previously interpreted. The result of the categorisation is then compared to the spatial distribution of outcrop data to build the geological model. The application of this approach to the Central Domain of the Mbere Division led to the production of a synthetic geological map at a scale of 1/75,000. The superposition of this map to the topographic model allows to observe a concordance between the Cretaceous basins represented by their edge faults and the topographic depression zones. The various mineral indicators (primary and secondary) collected during the fieldwork, combined with the geological model (1:75,000 scale) as well as the Cretaceous deposits and vein intrusion models were used to create the mineral indicators and targets map for this sector. All these models can thus be used to underpin mineral exploration projects in the study area. [ABSTRACT FROM AUTHOR]

Geophysical methods depend on a range of physical and chemical mechanisms, and each method has different sensitivities and resolution of Earth parameters, and over different scale lengths. Additionally, such geophysical methods will also have their own statistical characteristics. Thus, it is a significant challenge to combine different methods through a single inversion framework. Rather than attempting to find an optimal and single model for different geophysical responses, an alternative approach is to use FCM clustering to identify clusters of parameters from two or more different geophysical data sets or models that have similar statistical properties. In this paper, we apply the FCM approach to integrate data and model sets for an array of 100 broadband magnetotelluric (MT) and 100 passive seismic receivers spaced 1 km apart on a 10 by 10 grid above the Vulcan IOCG prospect in the Olympic Cu–Au Province, southern Australia. The challenge for exploration of the Vulcan prospect is that it lies beneath 750 m of regolith sedimentary cover, no single geophysical method provides a unique characterization of the deposit geometry, and drilling is very expensive. Fuzzy c-mean cluster analyses are undertaken in 2D for gravity data and shear-wave velocity model data for basement depths beneath cover and in 3D for shear-wave velocity and electrical resistivity model data. Fuzzy c-mean clustering is shown to provide a simple and efficient method of integrating different geophysical measurements to produce a geological framework that can be verified with drilling information. [ABSTRACT FROM AUTHOR]

La exposición a la gravedad artificial (GA), a través de la centrifugación humana, constituye la base del tratamiento denominado terapia gravitacional (TG), mediante el cual se produce un estímulo mecánico sobre la pared vascular induciendo la síntesis y liberación de prostaciclina. Se usa desde hace más de cuatro décadas en Uruguay en el tratamiento de enfermedades de base vascular. En la esclerosis sistémica (ES) ha demostrado gran beneficio y excelente perfil de seguridad. Sin embargo, existe un desconocimiento en la comunidad científica acerca de la TG y de sus resultados. Evaluar la eficacia de la TG en la afección cutánea y vascular, calidad de vida y capacidad funcional y su perfil de seguridad en pacientes con ES. Estudio descriptivo y retrospectivo de pacientes con ES asistidos en un centro de autoinmunidad de Montevideo, tratados con TG en los últimos 10 años. Se incluyeron 50 pacientes: 48 mujeres (96%) y 2 hombres (4%), con una edad media de 62 ± 12 años. El tiempo medio de evolución de la ES al momento de inclusión en el estudio y al iniciar la TG fue de 6,8 ± 3,2 años y de 2,8 ± 3,2 años, respectivamente. Post-TG se observó una mejoría significativa del puntaje modificado de Rodnan (mRSS) (pre-TG 19,2 ± 8,7 vs post-TG 5,4 ± 5,0, p < 0,05), que no se relacionó con el tiempo de evolución de la enfermedad al inicio de la TG, extensión cutánea o perfil inmunológico. El grado de mejoría post-TG se correlacionó con un mayor mRSS inicial (R = 0,84, p < 0,05). Se observó mejoría significativa del número de pacientes con puffy fingers (pre-TG 50% vs post-TG 20% pacientes, p < 0,05), pero no en telangiectasias, pitting scars o esclerodactilia. La gravedad del fenómeno de Raynaud disminuyó significativamente, pre-TG: grado 3-4, 43/48 (89,6%) pacientes vs post-TG: grado ≤ 2, 42/47 (89,4%) pacientes, p < 0,05, así como también el dolor vascular medido por EVA (escala 0-10) (pre-TG: 7,6 ± 2,2 vs post-TG: 1,4 ± 1,2, p < 0,05). También se registraron casos de curación de úlceras digitales. En cuanto a los resultados reportados por los pacientes, el 97% refirieron mejoría en calidad de vida y el 89,5% mejoría en capacidad para realizar actividades de la vida diaria. No se registraron efectos adversos significativos. La TG mejoró el compromiso cutáneo y vascular, la calidad de vida y la capacidad funcional en pacientes con ES con excelente perfil de seguridad. Se necesitan ensayos clínicos controlados y aleatorizados para corroborar estos resultados observacionales. The exposure to artificial gravity (AG) through human centrifugation is the basis of the treatment called gravity therapy (GT), in which the mechanical stimulation over the vessel wall, induces the synthesis and release of prostacyclin. It has been used for more than four decades in Uruguay in the treatment of different vascular-based pathologies. In patients with systemic sclerosis (SSc) it has shown good benefits and excellent safety profile over the years. However, there is a lack of knowledge in the scientific community about GT and its results. To evaluate the effectiveness of GT in cutaneous and vascular involvement, in the quality of life and functional capacity and its safety profile in patients with SSc. It is a descriptive and retrospective study of patients with SSc assisted in an autoimmunity center in Montevideo, treated with GT in the last 10 years. Fifty patients were included, 48 women (96%) and 2 men (4%) with a mean age of 62 ± 12 years. The mean time of evolution of SSc at the time of inclusion in the study at the beginning of GT was 6.8 ± 3.2 years and 2.8 ± 3.2 years respectively. After GT, a significant improvement in the modified Rodnan skin score (mRSS) was observed (pre-GT 19.2 ± 8.7 vs post-GT 5.4 ± 5.0, P <.05), which was not related to the time of disease progression at the beginning of GT nor to the skin extension or immunological profile. The degree of improvement post-GT was related to a higher initial mRSS (R = 0.84, P <.05). Also, a significant improvement was observed in the number of patients with puffy fingers (pre-GT 50% vs post-GT 20% patients, P <.05), but not in telangiectasias, pitting scars or sclerodactyly. The severity of Raynaud's phenomenon significantly decreased (pre-GT: grade 3-4, 43/48 (89.6%) patients vs post-GT: grade ≤ 2, 42/47 (89.4%) patients, P <.05) as well as the vascular pain measured with VAS (0-10 scale) (pre-GT: 7.6 ± 2.2 vs post-TG: 1.4 ± 1.2, P <.05). The healing of digital ulcers was also recorded. Regarding the results reported by patients, 97% reported improvement in the quality of life and 89.5% improvement in the ability to carry out activities of daily living. No significant adverse effects were recorded. GT improved cutaneous and vascular involvement, the quality of life and the functional capacity in patients with SSc with an excellent safety profile. Randomized, controlled clinical trials are needed to corroborate these observational results. [ABSTRACT FROM AUTHOR]

The results of the first high-precision airborne gravimetric route survey, which was conducted in 2023 along a transverse profile of Lake Baikal at a flight altitude of 5300 m, are presented. The use of an airborne gravimetric complex based on the AN-26BRL aircraft–laboratory is described. Directly over the lake, the largest negative measured anomaly of the gravity field was –180.8 mGal and the horizontal gradient of the field measurement was up to 9 and 5 mGal/km for the western and eastern shores of Lake Baikal, respectively. The internal convergence of anomaly values along the route profile for a complex of three gravimeters was 0.74 mGal. The estimations of the resolution and reliability of most topical current global models of the Earth's gravity field (UGM-SGG-2, EGM2008, XGM2019, and Sandwell and Smith v32) based on satellite data are assessed for the Baikal rift basin. It is shown that the mean square deviations of the field along the entire profile between the values calculated from satellite models with a number of spherical harmonic coefficients of ≥2190 and the airborne gravimetric observations are 9.5‒17.9 mGal, whereas the maximum deviations at individual points of the route are 40–80 mGal. The comparison with data on the marine gravimetric survey on a scale of 1 : 500 000 is carried out using airborne profile data. Due to the highly detailed data along the airborne gravimetry profile, it is established that the factual value of the main negative anomaly on the air profile is higher than that accepted for the analysis and complex interpretation of geophysical data in the area of Lake Baikal. [ABSTRACT FROM AUTHOR]

This paper proposes a new model for anisotropic compact stars with quintessence in Rastall teleparallel gravity via embedding approach. In the gravity, the acquired field equations encompassing the anisotropic matter source as well as the quintessence field are studied using the specific character of the scalar torsion T for the observed stars candidates PSRJ 1416–2230, 4U 1608–52, CenX–3, EXO 1785–248 and SMC X–1. All of the stellar structures under consideration are said to be advantageously independent of any central singularity and are stable. A thorough graphical analysis reveals that numerous physical properties critical for forming stellar structures are satisfied. [ABSTRACT FROM AUTHOR]

The matter–anti-matter asymmetry in the early Universe's history is explained theoretically by the baryogenesis. It is well known that modified gravity theories are highly effective in explaining the Universe's current accelerated state. In this paper, we examine the gravitational baryogenesis for f (Q , C) gravity, where Q is the non-metricity scalar and C is the boundary term. To perform the baryogenesis, we assume linear, nonlinear and logarithmic forms of f (Q , C). We evaluate the baryon-to-entropy ratio for our models by assuming the power law form of the scale factor a (t) = a 0 t δ . We also investigate the generalized baryogenesis for our model by assuming the interaction term ∂ μ (Q + C). We constrain the model parameters by comparing with the observational value η B s = 9. 4 2 × 1 0 − 1 1 . Our derived models are physically viable. [ABSTRACT FROM AUTHOR]

This paper examines the viable characteristics of anisotropic compact stars in f (ℜ , T 2) theory (ℜ is the Ricci scalar and T 2 = T α β T α β ). In this perspective, we use Tolman–Kuchowicz solutions (μ = w r 2 + 2 ln z and ν = ln (1 + x r 2 + y r 4)) to examine the configurations of static spherically symmetric structures. The unknown constants are found by the first fundamental form of Darmois junction conditions. We analyze the behavior of fluid parameters in the interior of 4U 1538-52, PSRJ 1614-220, EXO 1785-248 and SAXJ 1808.4-3658 compact stars correspond to different models of this theory. Furthermore, the stability of the proposed compact stellar objects is examined through sound speed and adiabatic index methods. The satisfaction of requisite conditions ensures that stable compact objects exist in this framework. [ABSTRACT FROM AUTHOR]

In this work, the spherically symmetric wormhole solutions have been obtained in the four-dimensional Einstein–Gauss–Bonnet (4D EGB) gravity with isotropic and anisotropic matter sources. With each type of source, the traversable wormholes satisfying asymptotic flatness and flare-out conditions are developed. Further, the energy conditions explaining the nature of the matter in the interior of the wormhole are tested and the stability of wormhole solutions has been analyzed. [ABSTRACT FROM AUTHOR]

This study is dedicated to investigate the Noether symmetry approach in a newly introduced gravitational theory known as f (R , G , T) gravity, where f is the function of Ricci scalar R , trace of energy–momentum tensor T , and the Gauss–Bonnet invariant term G. The Noether symmetry approach plays a supportive role in generating models and then determining the exact solutions by using the conserved quantities. For this purpose, the flat Friedmann–Robertson–Walker space–time is selected to observe cosmic evolution. The set of partial differential equations is calculated in the background f (R , G , T) modified theory gravity. We further examine the four different f (R , G , T) gravity models and calculate the conserved quantities to investigate the exact solutions. The three models show the increasing behavior of the cosmic scale factor that supports the expansion of universe. In fourth model, we are able to get the corresponding conserved quantity only and it is anticipated that this model will also support the expansion of universe. [ABSTRACT FROM AUTHOR]

The introductory paper sets the stage for the research essays in the special issue. It provides an overview of the concepts of minilateralism and the context in which minilateralism has become an alternative form of collective action by states in the international arena, in particular in the Indo-Pacific region that has emerged as the new centre of gravity in world politics. How has minilateralism become a prominent feature of inter-state cooperation in the early twenty-first century, and how is it often used to complement (and in some cases, even substitute for) traditional international organisations, which are based on more liberal and inclusive multilateral norms and principles, but suffering from functional deficits? In a world of more diffuse power, how can minilateralism offer states an expanded toolset for pursuing their policy preferences and advancing their interests? At the same time, the paper also highlights the potential negatives of (or challenges to) minilateralism, including difficulties emanating from a narrowly framed agenda that perpetuates certain narratives, a leadership vacuum that could emerge from non-hierarchical arrangements, and questions about how to achieve support and legitimacy with low institutionalisation. [ABSTRACT FROM AUTHOR]

To address the limited consideration of coarse particles in existing studies on gravity flow of caved ore and rock, this study conducted physical and numerical draw tests. The purpose was to investigate the flow characteristics of caved ore and rock under the influence of different numbers, relative positions, and spacing of coarse particles. The analysis focused on the perspective of interparticle interaction, considering the evolution laws of unbalanced force, void fraction, and force chains. The main research findings are as follows: (1) As the number of coarse particles increases from one to four, the size ratio of coarse and fine particles, which has similar effects on the shape of IMZ, decreases from 6.0 to 4.0. (2) When two coarse particles are arranged vertically and in contact, there is no significant separation between them, and the agglomeration effect of the force chain is the most prominent. [ABSTRACT FROM AUTHOR]

Starting from observed variations of the length of day in the past 2.5 billion years, we calculate the corresponding gravity variation and evaluate the possible effects that such variation would have induced on the lithosphere and on mantle convection. The lithospheric stress induced by the observed gravity increase at the equator in 500 Ma is of the same order as the one associated with a convective cell. We model a gravity increase that would result in 1.3 × 10−2 µGal or 1.3 × 10−10 m s−2 over 10 years, a value that is not far from the detection thresholds of modern gravimeters. Gravity increase also affects mantle dynamics by improving convection efficiency. Our models demonstrate that gravity variations contribute to this phenomenon through faster and wider mixing. The results support a view where a convective system being subject to gravity changes responds through non-linear adjustments of its effective mixing at all scales. These findings contribute to a deeper understanding of how gravitational fluctuations may shape the behavior of Earth's dynamic systems over geological timescales. [ABSTRACT FROM AUTHOR]

Deltas are deposits directly accumulated by land‐generated gravity flows in a standing body of water. The paradigm of deltaic sedimentation has dramatically changed during recent years, from the popular very simplified ternary models of marine littoral deltas towards more realistic and comprehensive models, considering the importance of sediment‐laden river discharges. Ternary delta models were designed for clean rivers, where a stream flow drags the sediments. Depending on the basin dynamics, these littoral deposits can be modified, forming tidal‐dominated, wave‐dominated or fluvial‐dominated littoral deltas. In recent years, a new classification of delta systems was proposed, based on contrasting the salinity of the receiving water body with the bulk density of the incoming fluvial discharge. Rivers are highly dynamic systems, and their discharges can be very variable in terms of flow duration and sediment concentration. Additionally, the salinity of the receiving water body can exhibit significant variability, especially in closed lakes and epicontinental seas, ranging from freshwater to brines. This scenario allows the distinction of three major delta categories (hypopycnal, homopycnal and hyperpycnal deltas) which can be in turn subdivided, defining seven delta types. Hypopycnal deltas form when the bulk density of the incoming flow is lower than the density of the water in the basin, allowing the definition of three delta types, corresponding to hypersaline littoral deltas, marine littoral deltas and brackish littoral deltas. Homopycnal deltas form when the bulk density of the incoming flow is similar to the density of the water in the basin, defining a delta type termed homopycnal littoral deltas. Hyperpycnal deltas form when the bulk density of the incoming flow is higher than the density of the water in the basin, allowing the definition of three categories termed hyperpycnal littoral deltas, hyperpycnal subaqueous deltas and hyperpycnal fan deltas. [ABSTRACT FROM AUTHOR]

Developing a two-country oligopoly model with firm heterogeneity, this paper examines the relationship among market size, the Home Market Effect, and the gravity equation. We show that in the long-run with free entry, the Home Market Effect holds, namely, more firms locate in the large-sized country. This leads the large-sized country to be a net exporter of the oligopoly good. In the short-run with restricted entry, the Home Market Effect no longer holds and the large-sized country becomes a net importer of the oligopoly good. These results suggest that the theoretical predictions of Feenstra et al. (Can J Econ 34(2):430–447, 2001) survive firm heterogeneity. [ABSTRACT FROM AUTHOR]

The gas-liquid separator serves as a crucial component within AEL integrated with renewable energy sources. It is used to separate gas and lye within the circulating solution, thereby enhancing hydrogen production efficiency and mitigating gas crossover phenomena. However, the separation performance of separators is influenced by fluctuations in processing capacity, attributable to the stochastic nature and volatility of renewable energy. The separation efficiency of gravity gas-liquid separators is investigated in this paper. The separation efficiency is 88.28% (experiment) and 90.0% (simulation). Nevertheless, the ability of gravity gas-liquid separators to sustain great separation performance amidst fluctuations in processing capacity is compromised. Moreover, separation efficiency is diminished with increasing gas content and velocity. A spiral diversion gas-liquid separator is proposed with the separation efficiency is up to 96.4%. The spiral diversion gas-liquid separator proves to be a more suitable choice for AEL integrated with renewable energy sources. • Capacity fluctuation is a characteristic of the AEL. • The separation performance is inevitably affected by capacity fluctuation. • The gravity gas-liquid separator exhibits low separation efficiency. • The spiral diversion gas-liquid separator is adaptable to capacity fluctuation. • The separation performance of spiral diversion gas-liquid separator is 96.4%. [ABSTRACT FROM AUTHOR]

In this paper, our investigation focuses on the cosmic history in modified f(Q) gravity, a different theory that describes the gravitational force using a non-metricity scalar. The equations of the theory are solved by assuming a parametric form for the deceleration parameter. The parameters of the model are estimated by using the Cosmic Chronometer dataset. A number of parameters, like the deceleration parameter, whose signature changes with redshift and shows typical behavior in late-time cosmology, are subject of our analysis. We also show the evolution of other parameters, such as the equation of state parameter and energy density. The parametrization approach used here in f(Q) modified gravity provides a better description of the late-time cosmic evolution without dark energy. [ABSTRACT FROM AUTHOR]

This work presents the application of the q‐algebra in the glueball spectrum. This algebra is implemented through Jackson's derivatives in a Schrödinger‐like equation resulting from the gravity fluctuations around the braneworld scenario in five dimensions. In our prescription, we consider a four‐dimensional AdS4 brane, living in AdS5 bulk, that is also known for describing locally localized gravity via quasizero mode. At the appropriate limit, this background leads to confinement and allows us to find the shape of the q‐deformed glueball spectrum in the AdS5/QCD4 correspondence. The introduction of the q‐deformation provides us with a richer glueball spectrum. [ABSTRACT FROM AUTHOR]

If entanglement builds spacetime, then conversely, disentanglement ought to destroy spacetime. From the quantum null energy condition and quantum focusing conjecture, we obtain disentanglement criteria which necessitate infinite energies and strong spacetime singularities. We apply our results to the strong cosmic censorship proposal, where singularities at the Cauchy horizons in black holes are desirable. Using our disentanglement criteria and without resorting to any detailed calculations, we provide an exceedingly general and physically transparent discussion of strong cosmic censorship in semiclassical black holes. We argue that strong cosmic censorship is enforced in asymptotically flat and de Sitter black holes by disentanglement and describe how similar disentanglement might be avoided in some anti-de Sitter cases. [ABSTRACT FROM AUTHOR]

Education as a journey of human becoming involves commitment to one’s ethical life project as well as learning to live well and actively participate with others in an ever-changing socio-cultural, political and material world. This paradoxical journey is at the heart of our philosophical criticism of contemporary policy impulses to formulate risk averse pedagogies which centre on a product model of outcomes. We draw from philosophical perspectives of liminality and the Productive Pedagogy study from Australia to inform our position by indicating how students make sense of pedagogical experiences in unique, deeply personal, corporeal and limitlessness ways. We use Aquatics Education as a useful symbolic representation for the immersive, embodied and relational practices involved in human becoming; practices that we aver need to be acknowledged, while never fully defined. These practices require teachers’ localised autonomous judgements in evaluating risk for dilemmas encountered. Holistic experiences, provided by games with gravity, are consistent with such ‘aesthetic experiences’ for primacy of the subject/subjective. Our affirmative critique reveals how immersive experiences occupy a defensible position for our concept of a Productive Pedagogy of Liminality, which aims to open affordances for each student’s ethical life project by heightening subjective awareness between body and spirit. [ABSTRACT FROM AUTHOR]