Physical Situations Research Articles

Physical aspects of quantile residual lifetime sequence

Abstract The modeling of count data is found in many fields, such as statistical physics, public health, medicine, epidemiology, applied science, sociology, and agriculture. In many physical situations, it has been observed that many times in the real world, the original variables may be continuous in nature, but discrete by observation. In this study, the α {\rm{\alpha }} -quantile residual life function for discrete lifetime models is defined and some attributes are investigated. The relation between this measure and the hazard rate function is studied. We discuss how this measure could be useful for finding the burn-in time of a lifetime dataset. Then, a new stochastic order based on the α {\rm{\alpha }} -quantile residual life is proposed and studied.

THE IMPACT OF SOLAR RADIATION ON THE TEMPERATURE REGIME OF A ROOM IN WINTER

The article is devoted to the computational studies of the air-thermal state of office premises taking into account the effect of solar radiation coming through window openings. The study was conducted for a room with two windows using two heating devices installed under them. The air-temperature regime of premises in winter, characterized by the highest thermal energy consumption for heat supply, is considered. The study is based on the solution of a three-dimensional nonlinear heat transfer problem described by a system of equations of turbulent momentum and energy transfer. The k-e turbulence model is used to close this system. The results of numarical modeling of the physical situation under study are presented. The research data on the features of the air-thermal state of the premises under solar radiation conditions are given. The results of a comparative analysis of the air-temperature conditions of office premises corresponding to the solution of the specified heat exchange problems in the presence and absence of solar radiation are presented and the effects of solar radiation on the structure of the air flow and the thermal state of the premises are established. It is shown that in the presence of solar radiation, the air flow picture and the character of the temperature fields in the premises change significantly. In particular, in these conditions, the increase in the average temperature of the premises for the studied period is 2.5 °С. The possibility of a certain reduction of the load on the heating system in the presence of solar radiation is noted. Bibl. 17, Fig. 5.

The impact of quantum correlations on parameter estimation in a spin reservoir

We study the impact of quantum correlations existing within the system-environment thermal equilibrium state while estimating the parameters of the spin reservoir. By employing various physical situations of interest, we present results for the reservoir temperature and its coupling strength with the central two-level system. The central system (probe) interacts with the bunch of randomly oriented spin systems and attains a thermal equilibrium state. We consider a projective measurement which prepares the probe’s initial state, and then the global system (probe and reservoir) evolves unitarily. The reduced density operator encapsulates the information about the spin reservoir which can be extracted by doing measurements on the probe. The precision of such measurement is quantified by quantum Fisher information. We repeat this process if the probe-reservoir initial state is not correlated (product state). We compare the estimation results for both with and without the outturn of initial correlations. In the temperature estimation case, our results are promising as one can significantly improve the accuracy of the estimates by including the effect of initial correlations. A similar trend prevails in the case of coupling strength estimation especially at low temperatures.

Tachyons in “momentum-space” representation

Obtaining the momentum space associated with tachyonic “particles” from the Poincaré group manifold proves to be rather intricate, departing very much from the ordinary dual to Minkowski space directly parametrized by space-time translations of the Poincaré group. In fact, although described by the constants of motion (Noether invariants) associated with space-time translations, they depend non-trivially on the parameters of the rotation subgroup. However, once the momentum space is parametrized by the Noether invariants, it behaves as that of ordinary particles. On the other hand, the evolution parameter is no longer the one associated with time translation, whose Noether invariant, Po, is now a basic one. Evolution takes place in a spatial direction. These facts not only make difficult the computation of the corresponding representation, but also force us to a sound revision of several traditional ingredients related to Cauchy hypersurface, scalar product and, of course, causality. After that, the theory becomes consistent and could shed new light on some special physical situations like inflation or traveling inside a black hole.

국내 2형 당뇨병 애플리케이션의 디자인 사례 연구 - 20~30대가 선호하는 애플리케이션 중심으로

According to statistics from the Korea Health Insurance Review and Assessment Service, the number of diabetes patients in their 30s stood at 121,568 as of 2020, up 25.5% from four years ago. In particular, the prevalence of young diabetes patients in their 20s increased by 47% from 23,798 in 2016 to 35,005 in 2020. They are at high risk of complications due to their long disease life, so the importance of the diabetes management app is drawing attention for steady management and continuous information, but most apps are being developed focused on middle-aged people. There is inevitably a difference between the living environment of middle-aged people and those in their 20s and 30s, but due to the characteristics of the younger generation, which has a high proportion of single-person households, it is difficult to manage diabetes on their own. For young diabetics and diabetes patients in their 40s or older, there will be differences in the areas that are directly or indirectly affected by the living environment and social environment, so the preferred design will change and the physical situation will be affected, which will affect the user interface. Looking at the two objects together and developing diabetes applications will inevitably cause inconvenience to users. Recognize the gap between the two targets and see the need for applications used by young diabetes patients who have been pushed out of development targets, not applications for existing middle-aged people. Therefore, the study conducted a basic study for developing applications suitable for young diabetes patients by comparing applications preferred by people in their 20s and 30s with the design characteristics of diabetes management apps in order to develop applications that can help young diabetics manage diabetes on their own. The paper compared and analyzed the most frequently used and existing diabetes applications in their 20s and 30s. Currently, for diabetes applications, there is a lack of fun factors that can increase user access, leading to the need to develop fun factors that can help young diabetics manage continuously.

Regularity and uniqueness of solutions for compressible non-newtonian MHD equations with variable electrical conductivity and energy effects

This paper examines the existence, uniqueness, and regularity of solutions for a system of compressible non-Newtonian magnetohydrodynamics (MHD) equations with variable electrical conductivity and considering the energy equation. We establish the necessary conditions on fluid properties, external forces, and initial and boundary conditions to ensure the well-posedness of the system. Our results demonstrate the existence of regular solutions in appropriate functional spaces, the uniqueness of these solutions, and their higher regularity under smooth initial and boundary conditions. These findings provide a mathematical baseline for the study of complex interactions in compressible non-Newtonian MHD flows, and particularly the findings can be considered to support more accurate numerical simulations concerning a physical situation as well as deeper analytical solutions.

Anisotropic Durgapal-Fuloria compact stars in f(R) gravity

This study presented a new exact solution for anisotropic compact stellar objects within the framework of f(R)=R+αR2 gravity. In this context, the Durgapal-Fuloria metric potential has been employed to solve the field equation derived for f(R) theory. Furthermore, we have derived the generalized Darmois-Israel junction condition necessary for seamlessly connecting the interior region to the Schwarzschild exterior metric across the boundary hypersurface of the star in the context of f(R) gravity, and the interior solution is matched with the Schwarzschild exterior metric over the bounding surface of a compact star. These junction conditions stipulate that the pressure must not be zero at the boundary and should be proportional to the non-linear terms of f(R) gravity, a crucial aspect often overlooked by many researchers when investigating compact stellar models. Additionally, we derived the values of these parameters by using observational data of various compact stars (CSs), namely Her X-1, SAX J1808.4-3658, SMC X-1, LMC X-4, Cen X-3, 4U 1820-30, PSR J1903+327, 4U 1608-52, Vela X-1, and PSR J1416-2230. This approach enables us to investigate the comprehensive analysis of solutions numerically and graphically. We conducted various physical tests, including gradient of energy density and pressures, anisotropy, stability, equilibrium conditions, energy-density constraints, mass function, compactness, redshift, and adiabatic index, to assess the feasibility of our models. Our findings demonstrate the consistent behavior of our models provides a satisfactory physical situation as far as the observational results are confirmed.

Quantum Field Theory of Black Hole Perturbations with Backreaction: I General Framework

In a seminal work, Hawking showed that natural states for free quantum matter fields on classical spacetimes that solve the spherically symmetric vacuum Einstein equations are KMS states of non-vanishing temperature. Although Hawking’s calculation does not include the backreaction of matter on geometry, it is more than plausible that the corresponding Hawking radiation leads to black hole evaporation which is, in principle, observable. Obviously, an improvement of Hawking’s calculation including backreaction is a problem of quantum gravity. Since no commonly accepted quantum field theory of general relativity is available yet, it has been difficult to reliably derive the backreaction effect. An obvious approach is to use the black hole perturbation theory of a Schwarzschild black hole of fixed mass and to quantize those perturbations. However, it is not clear how to reconcile perturbation theory with gauge invariance beyond linear perturbations. In recent work, we proposed a new approach to this problem that applies when the physical situation has an approximate symmetry, such as homogeneity (cosmology), spherical symmetry (Schwarzschild), or axial symmetry (Kerr). The idea, which is surprisingly feasible, is to first construct the non-perturbative physical (reduced) Hamiltonian of the reduced phase space of fully gauge invariant observables and only then apply perturbation theory directly in terms of observables. The task to construct observables is then disentangled from perturbation theory, thus allowing to unambiguously develop perturbation theory to arbitrary orders. In this first paper of the series we outline and showcase this approach for spherical symmetry and second order in the perturbations for Einstein–Klein–Gordon–Maxwell theory. Details and generalizations to other matter and symmetry and higher orders will appear in subsequent companion papers.

Conformal Killing gravity: pp-waves; multiple matter sources

Abstract Recently Harada proposed a gravitational theory which is of third order in the derivatives of the metric tensor. This attracted some attention particularly as it predicts a late-time transition from cosmological deceleration to accelerated expansion without assuming the presence of dark energy or a non-zero cosmological constant. This theory has been dubbed conformal Killing gravity (CKG). The most general exact solutions of the Harada field equations are known for a number of important physical situations: homogeneous and isotropic cosmological models, static spherically symmetric vacuum and electrovac spacetimes. These are analogues of the well-known FRWL, Schwarzschild and Reissner–Nordström metrics of general relativity (GR). In this paper a subclass of pp-waves are studied and the most general exact solution obtained together with its specialization for plane waves. The generalization from GR to Harada’s theory is straightforward. The solutions have Petrov type N or 0 and the Ricci tensor is either zero or the Segré type is [(211)] with zero eigenvalue. For any metric in CKG it is shown that more than one possible matter source can generate the solution. If the metric admits one or more Killing vectors or Killing tensors, the ambiguity in the possible matter sources increases.

Reamputation Rate, Mortality, and the Incidence of Risk Factors for Ipsilateral Reamputation Among Patients with Dysvascular Major Lower Limb Amputation

A major lower-limb amputation (LLA) for dysvascular disease carries the risk of disturbed wound healing necessitating reamputation at a higher level. A reamputation causes a delay in prosthetic fitting and recovery of walking ability. The combination of a prolonged open wound and inability to walk can worsen of the physical and psychological situation. Prevention of reamputation seems therefore important. This study aims to identify risk factors for reamputation, and to evaluate a possible altered mortality rate after a dysvascular major LLA. These issues are crucial for shared decision-making prior to surgery. Retrospective study investigating a Dutch regional cohort of patients with a dysvascular below-knee, through-knee, or above-knee LLA. 516 Dysvascular major LLAs were included (2014-2018). One hundred reamputations were performed within 1 year after initial amputation (19.4%). Risk factors for ipsilateral reamputation were diabetes mellitus, lipid-lowering drugs usage, and lower level of amputation (respectively P = < 0.01, 0.037, and < 0.01). The 30-day mortality rates were 1% and 12% for the reamputation group and the non-reamputation group respectively (P = < 0.01). The 1-year mortality rates were 23% and 27% for the reamputation group and the non-reamputation group respectively (P = 0.423). Ipsilateral reamputation within one year after initial amputation is common. Several risk factors for reamputation were identified. The 30-day and 1-year mortality rate is high, but not significantly different after one year. A clinical decision tool for dysvascular patients needs to be developed to improve shared decision-making, reduce reamputation rates, and improve survival.

The Lorenz ratio as a guide to scattering contributions to transport in strongly correlated metals

In many physical situations in which many-body assemblies exist at temperature T, a characteristic quantum-mechanical time scale of approximately [Formula: see text] can be identified in both theory and experiment, leading to speculation that it may be the shortest meaningful time in such circumstances. This behavior can be investigated by probing the scattering rate of electrons in a broad class of materials often referred to as "strongly correlated metals". It is clear that in some cases only electron-electron scattering can be its cause, while in others it arises from high-temperature scattering of electrons from quantized lattice vibrations, i.e., phonons. In metallic oxides, which are among the most studied materials, analysis of electrical transport does not satisfactorily identify the relevant scattering mechanism at "high" temperatures near room temperature. We therefore employ a contactless optical method to measure thermal diffusivity in two Ru-based layered perovskites, Sr3Ru2O7 and Sr2RuO4, and use the measurements to extract the dimensionless Lorenz ratio. By comparing our results to the literature data on both conventional and unconventional metals, we show how the analysis of high-temperature thermal transport can both give important insight into dominant scattering mechanisms and be offered as a stringent test of theories attempting to explain anomalous scattering.

"Track style" children's fundamental movement skills test: construction and verification of an efficient evaluation system.

This study aimed to develop an efficient tool for assessing children's fundamental motor skills, the "Track style" Children's Fundamental Movement Skills Test (TCFMST), based on theories of motor development integrated with Chinese cultural context and physical education teaching situations. Starting from a literature analysis, the study selected items from existing fundamental movement skill (FMS) assessments, textbooks, physical education and health standards, and children's movement guidelines to construct a pool of test items. Subsequently, the items were screened and optimized using the Delphi method. Finally, the feasibility, discrimination, difficulty, reliability, and validity of the constructed test were examined using testing methods. The TCFMST includes three dimensions: locomotive skills, body control skills, and manipulative skills, with a total of 10 items. The difficulty and discrimination of each item are appropriate; the correlation coefficients for retest reliability range from 0.789 to 0.943 (p < 0.01). The results of exploratory factor analysis indicate that the common factors align with the hypothesized three dimensions, indicating good structural validity of the test. The concurrent validity results show a correlation coefficient of -0.510 (p < 0.01) between the TCFMST and the total score of TGMD-3, indicating a moderate correlation between the two tests. The TCFMST developed in this study has good difficulty, discrimination, reliability, and validity. It also features strong operability, a short duration, and high interest. It can serve as an important tool for monitoring children's fundamental motor skill levels.

A Diffusion Model to Describe Water Absorption by Red Rice during Soaking: Variable Mass Diffusivity, Variable Volume, Use of Boundary-Fitted Coordinates

This article aims to carry out experiments on water absorption by husked red rice at constant temperatures of 28, 40, and 50 °C. The description of the absorption kinetics and the analyses of the water distribution and volumetric expansion of each grain, at a given instant, were carried out using a diffusion model. In order for the model to be as close as possible to the real physical situation, the mesh necessary to numerically solve the diffusion equation was generated from the photograph of a grain. Thus, the diffusion equation was written in Boundary-Fitted Coordinates (BFCs). The solution of the diffusion equation written in generalized coordinates was then discretized in space and time, using the Finite Volume method, with a fully implicit formulation, considering the variable volume and variable mass diffusivity as functions of the local moisture content. Optimizations based on the Levenberg–Marquardt algorithm make it possible to determine the parameters of an exponential function relating mass diffusivity and the local moisture content for each temperature. Statistical indicators (chi-square, determination coefficient, and Student’s t-test) allowed us to conclude that the proposed model was very satisfactory for all temperatures, making it possible to simulate the water absorption, water distribution, and volumetric expansion of the grain over time.

Communication on the move among the Baka people

This article investigates the movement and communication of hunter-gatherers during the group moving activities, based on participant observation and interaction analysis of visual and audio materials recorded in the field. The communication aspects are multimodal while people are on the move. Based on this, diverse knowledge is generated and transmitted. However, there is limited understanding of how the hunter-gatherers encounter each other and begin communication while on the move. In particular, the physical situation during the group moving activity in environments with visual obstacles, such as the rainforest, is not clear. This article provides the case of the Baka hunter-gatherers, living in the rainforest of southeastern Cameroon, to reveal aspects of the beginning of communication during the extended group moving activity. It shows that in the tropical forest, with its restricted visibility, participants’ physical situation is dynamic. Although this limitation of visibility constrained participants’ face-to-face communication, it diversified their distant communication, which does not require seeing each other. Such non-face-to-face communication provided participants with a wider range of communication while walking together.

Non-triviality of an asymptotically flat vacuum spacetime in pure R2 gravity

In [Phys. Rev. D 107, 104008 (2023)], we reported a novel exact closed-form solution which describes asymptotically flat spacetimes in pure [Formula: see text] gravity. The solution is Ricci scalar flat, viz. [Formula: see text] everywhere. Whereas any metric with a null Ricci scalar would trivially satisfy the [Formula: see text] vacuo field equation, [Formula: see text], in this paper, we shall show that our solution satisfies a “stronger” version of the [Formula: see text] vacuo field equation, viz. [Formula: see text], despite the term [Formula: see text] being singular. Even though [Formula: see text] identically vanishes, for our solution, the combinations [Formula: see text] and [Formula: see text] are free of singularity. This exceptional property sets our solution apart from the set of null-Ricci-scalar metrics and makes it a genuinely nontrivial solution. We further demonstrate that, as a member of a larger class of asymptotically de Sitter metrics, our solution is resilient against perturbations in the scalar curvature at largest distances, making it relevant for physical situations where the background deviates from asymptotic flatness.

Local versus Global Time in Early Relativity Theory.

In his groundbreaking 1905 paper on special relativity, Einstein distinguished between local and global time in inertial systems, introducing his famous definition of distant simultaneity to give physical content to the notion of global time. Over the following decade, Einstein attempted to generalize this analysis of relativistic time to include accelerated frames of reference, which, according to the principle of equivalence, should also account for time in the presence of gravity. Characteristically, Einstein's methodology during this period focused on simple, intuitively accessible physical situations, exhibiting a high degree of symmetry. However, in the final general theory of relativity, the a priori existence of such global symmetries cannot be assumed. Despite this, Einstein repeated some of his early reasoning patterns even in his 1916 review paper on general relativity and in later writings. Modern commentators have criticized these arguments as confused, invalid, and inconsistent. Here, we defend Einstein in the specific context of his use of global time and his derivations of the gravitational redshift formula. We argue that a detailed examination of Einstein's early work clarifies his later reasoning and demonstrates its consistency and validity.

Complex t-Intuitionistic Fuzzy Graph with Applications of Rubber Industrial Water Wastes

The main concept involved in this study explains the theme of complex t-intuitionistic fuzzy graphs (CTIFGs), which act as a powerful tool in analyzing and displaying the relationships among various applications that are difficult to recognize. The manuscript also demonstrates the capability of CTIFGs to create complex associations with multiple domains when considering a physical situation. Following this, the basic set of operations for CTIFGs is projected. The ideas on isomorphism and homomorphism of the CTIFGs are also presented. Moreover, the manuscript describes the importance of the above-mentioned technique in an effective way, giving a solution to the practical application associated with rubber processing industrial wastewater. The contributing factors and corresponding interdependencies are considered when calibrating the complex nature of industrial wastewater associated with the CTIFGs. The results highlight the adaptability and possible efficiencies of CTIFGs, which act as a decision-making tool and also indicate their importance for policy planners in important societal issues.

Tarsus historic city center, identification of problem and potentials as base for strategic guideline

Tarsus historic city center is a continuous settlement from the Neolithic Age to the present day. Archaeological heritage is integrated with traditional historic quarters, historic city center, Early Republican buildings and industrial heritage. Social practices, cultural production processes, legends and religious events transferred from generation to generation constitute the intangible cultural heritage elements and also the symbols of the city. In 2013, conservation area boundaries were revised and Tarsus historic city center, was declared as 3rd Grade Archaeological Site by the Regional Conservation Council. In defined context, the Conservation-Strategy Guideline was prepared with the contract signed between Mersin Metropolitan Municipality and Mersin University, Faculty of Architecture in 2022. Within the scope of document, a guideline containing urban conservation strategies for the historic city center of Tarsus has been prepared. Within the scope of this article, findings and evaluations regarding current situation based on field surveys and questionnaires that form the basis for the guideline are presented. The study aims to document the physical and socio-cultural situation of the historic center in 2022 to guide further studies concerning cultural heritage in Tarsus.

Estimation of monotone α-quantile of past lifetime function with application

Abstract In many physical situations, it is reasonable to assume that the α-quantile of past life functions is increasing. In this study, we propose a new estimator for an increasing α-quantile of the past life function for right-censored data. We investigate the asymptotic properties of the new estimator and explore its weak and strong convergence. The simulation results show that the new estimator is consistent and outperforms the usual estimator from the literature. As an illustrative example, a time event from a data set of the Mayo Clinic study on primary biliary cirrhosis was analyzed.

Tunable Non-Fermi Liquid Phase from Coupling to Two-Level Systems.

We study a controlled large-N theory of electrons coupled to dynamical two-level systems (TLSs) via spatially random interactions. Such a physical situation arises when electrons scatter off low-energy excitations in a metallic glass, such as a charge or stripe glass. Our theory is governed by a non-Gaussian saddle point, which maps to the celebrated spin-boson model. By tuning the coupling strength we find that the model crosses over from a Fermi liquid at weak coupling to an extended region of non-Fermi liquid behavior at strong coupling, and realizes a marginal Fermi liquid at the crossover. Our results are valid for generic space dimensions d>1.