Models Of Stars Research Articles

Compiled properties of nucleonic matter and nuclear and neutron star models from nonrelativistic and relativistic interactions

Compiled properties of nucleonic matter and nuclear and neutron star models from nonrelativistic and relativistic interactions

X-Shooting ULLYSES: Massive stars at low metallicity. V. Effect of metallicity on surface abundances of O stars

Massive stars rotate faster, on average, than lower mass stars. Stellar rotation triggers hydrodynamical instabilities which transport angular momentum and chemical species from the core to the surface. Models of high-mass stars that include these processes predict that chemical mixing is stronger at lower metallicity. We aim to test this prediction by comparing the surface abundances of massive stars at different metallicities. We performed a spectroscopic analysis of single O stars in the Magellanic Clouds (MCs) based on the ULLYSES and XshootU surveys. We determined the fundamental parameters and helium, carbon, nitrogen, and oxygen surface abundances of 17 LMC and 17 SMC non-supergiant O6-9.5 stars. We complemented these determinations by literature results for additional MCs and also Galactic stars to increase the sample size and metallicity coverage. We investigated the differences in the surface chemical enrichment at different metallicities and compared them with predictions of three sets of evolutionary models. Surface abundances are consistent with CNO-cycle nucleosynthesis. The maximum surface nitrogen enrichment is stronger in MC stars than in Galactic stars. Nitrogen enrichment is also observed in stars with higher surface gravities in the SMC than in the Galaxy. This trend is predicted by models that incorporate chemical transport caused by stellar rotation. The distributions of projected rotational velocities in our samples are likely biased towards slow rotators. A metallicity dependence of surface abundances is demonstrated. The analysis of larger samples with an unbiased distribution of projected rotational velocities is required to better constrain the treatment of chemical mixing and angular momentum transport in massive single and binary stars.

Impact of Newly Measured Nuclear Reaction Rates on 26Al Ejected Yields from Massive Stars

Over the last three years, the rates of all the main nuclear reactions involving the destruction and production of 26Al in stars (26Al(n, p)26Mg, 26Al(n, α)23Na, 26Al(p, γ)27Si and 25Mg(p, γ)26Al) have been re-evaluated thanks to new high-precision experimental measurements of their crosssections at energies of astrophysical interest, considerably reducing the uncertainties in the nuclear physics affecting their nucleosynthesis. We computed the nucleosynthetic yields ejected by the explosion of a high-mass star (20 M⊙, Z = 0.0134) using the FRANEC stellar code, considering two explosion energies, 1.2 × 1051 erg and 3 × 1051 erg. We quantify the change in the ejected amount of 26Al and other key species that is predicted when the new rate selection is adopted instead of the reaction rates from the STARLIB nuclear library. Additionally, the ratio of our ejected yields of 26Al to those of 14 other short-lived radionuclides (36Cl, 41Ca, 53Mn, 60Fe, 92Nb, 97Tc, 98Tc, 107Pd, 126Sn, 129I, 36Cs, 146Sm, 182Hf, 205Pb) are compared to early solar system isotopic ratios, inferred from meteorite measurements. The total ejected 26Al yields vary by a factor of ~3 when adopting the new rates or the STARLIB rates. Additionally, the new nuclear reaction rates also impact the predicted abundances of short-lived radionuclides in the early solar system relative to 26Al. However, it is not possible to reproduce all the short-lived radionuclide isotopic ratios with our massive star model alone, unless a second stellar source could be invoked, which must have been active in polluting the pristine solar nebula at a similar time of a core-collapse supernova.

Stellar Mapping Using Quadratic Limb-Darkening

Abstract In this thesis, I create useful visualizations of stars empirically from transit observations and theoretically from stellar parameters. Transit photometry has been a popular method to find exoplanets and information about star and planet systems many light-years away. Since most stars are too far away to be seen directly, creating stellar visualizations is an important tool for modeling stars. When creating visualizations, limb-darkening must be considered. Limb-darkening is the visual darkening along the outside, or limbs, of a star. This effect is more dramatic at shorter wavelengths, such as visible light, making it easier to see the darkening of limbs. A recent transit of WASP-39 captured from the James Webb Space Telescope is used to create stellar models for this star, using fitted empirical limb-darkening coefficients. Theoretical models for WASP-39 will also be created using theoretically determined coefficients. While complicated, generating empirical and theoretical limb-darkening profiles is a useful way of modeling stars too far away to observe. Lay summary We can locate brand new exoplanets, many light years away, without ever actually seeing them. Better yet, we can classify and learn vital information about the star and planet system from the exoplanet detection methods. One commonly used detection method is the transit method. The transit method captures the slight dimming of a star’s light as a planet crosses in front of it. This decrease in brightness is temporary and regular. Transits provide information about the composition and properties of stars. One such phenomenon is limb-darkening where the brightness of the star appears darker around its edges. Limb-darkening coefficients are calculated using a quadratic relationship between the intensity at a certain point of the star to the intensity at the center of the star. As the coefficients increase, the “limbs” or edges of the star appear darker. The wavelength in which we are measuring the transit also impacts the limb-darkening. At lower wavelengths, the darkening effect is more dramatic. Using these coefficients at different wavelengths we can create theoretical models to show what stars should look like without being able to see them. The James Webb Telescope (JWST) is capturing numerous exoplanets through the transit method. Launched in December 2021, the JWST contains instruments capable of measuring the slightest changes in the brightness of distant stars. The transit data, collected from the JWST, are fit to infer the best limb-darkening coefficients. We also calculate theoretical coefficients using known physical properties of the star. One particular star captured by the JWST is WASP-39, located 700 light years away. WASP-39 is a dwarf star slightly smaller than our Sun. Models of WASP-39 are created using the empirical and theoretical coefficients. These stellar movies show the appearance of the star at various wavelengths and their corresponding limb-darkening coefficients. The appearances are compared to show how different actual data presents from theoretical models. Providing visual models for stars is an easy way to quantify differences, rather than numerical data. To see the complete thesis, please visit https://scholar.colorado.edu/concern/undergraduate_honors_theses/5m60qt492

Depression and the Role of Perceived Stress Controllability During the COVID-19 Pandemic

Abstract The learned helplessness theory of depression suggests that a perceived loss of control over stressful events is associated with depression. However, little research has tested this relationship in humans, and there has been little to no discussion of the possible effect of biological sex. The present study examined the relationship between perceived stress controllability and depression in a sample of college students during the COVID-19 pandemic, and whether biological sex moderated this relationship. Participants (ages 18-38, N = 295) were university students who were enrolled in the study near the beginning of the COVID-19 pandemic and assessed across the subsequent eight weeks. Using remote surveys, we assessed stressors the participants had experienced as well as the amount of control they felt they had over each; we also assessed anhedonic depression via surveys. At baseline, there was a significant correlation between perceived stress controllability and depression. Biological sex was not a moderator of this relationship, but planned post hoc analyses revealed baseline perceived stress controllability was significantly associated with depression in females but not in males. Across the eight weeks of the study, there was not a significant relationship between change in perceived stress controllability and change in depression, and biological sex was not a moderator. Planned post hoc analyses, however, showed that there was a significant correlation between change in perceived stress controllability and change in depression in females but not in males. These results suggest a possible relationship between perceived stress controllability and depression in females. However, our results were mixed and therefore further research is necessary to elucidate the nature of the relationship between perceived stress controllability and depression, and the extent to which this is moderated by sex. If this relationship does exist, it could suggest a potential target for therapy, particularly in females. Lay Summary We can locate brand new exoplanets, many light years away, without ever actually seeing them. Better yet, we can classify and learn vital information about the star and planet system from the exoplanet detection methods. One commonly used detection method is the transit method. The transit method captures the slight dimming of a star’s light as a planet crosses in front of it. This decrease in brightness is temporary and regular. Transits provide information about the composition and properties of stars. One such phenomenon is limb-darkening where the brightness of the star appears darker around its edges. Limb-darkening coefficients are calculated using a quadratic relationship between the intensity at a certain point of the star to the intensity at the center of the star. As the coefficients increase, the “limbs” or edges of the star appear darker. The wavelength in which we are measuring the transit also impacts the limb-darkening. At lower wavelengths, the darkening effect is more dramatic. Using these coefficients at different wavelengths we can create theoretical models to show what stars should look like without being able to see them. The James Webb Telescope (JWST) is capturing numerous exoplanets through the transit method. Launched in December 2021, the JWST contains instruments capable of measuring the slightest changes in the brightness of distant stars. The transit data, collected from the JWST, are fit to infer the best limb-darkening coefficients. We also calculate theoretical coefficients using known physical properties of the star. One particular star captured by the JWST is WASP-39, located 700 light years away. WASP-39 is a dwarf star slightly smaller than our Sun. Models of WASP-39 are created using the empirical and theoretical coefficients. These stellar movies show the appearance of the star at various wavelengths and their corresponding limb-darkening coefficients. The appearances are compared to show how different actual data presents from theoretical models. Providing visual models for stars is an easy way to quantify differences, rather than numerical data. For the full text, please visit https://scholar.colorado.edu/concern/undergraduate_honors_theses/z890rv682.

IMPLEMENTASI NINE STEP METHODOLOGY DALAM PERANCANGAN DATA WAREHOUSE

Rapid technological developments require companies to create information systems that can organize and process company information effectively and efficiently. PT. Universal Karya Jaya is a company engaged in metal cutting services. The company does not have a running Information System yet. Therefore, it is necessary to have a good information system to support its business processes through data warehouse design. The design of the data warehouse uses the nine- step methodology from Kimball and uses star modeling so that PT. Universal Karya Jaya can make their company data integrated and help superiors analyze data for fast and accurate decision making. The goal to achieve from this research is to design a data warehouse model that suits the needs of the company and it is hoped that this design can be implemented at PT. Universal Karya Jaya to support their business processes. Meanwhile, the research method used for this research was literature study and interviews. With this data warehouse, it is hoped that it can assist companies in handling large amounts of data so that it can become a helping hand on inputs for stakeholders in the decision-making process.

An Efficient Tidal Dissipation Mechanism via Stellar Magnetic Fields

Recent work suggests that inwardly propagating internal gravity waves (IGWs) within a star can be fully converted to outward magnetic waves if they encounter a sufficiently strong magnetic field. The resulting magnetic waves dissipate as they propagate outward to regions with lower Alfvén velocity. While tidal forcing is known to excite IGWs, this conversion and subsequent damping of magnetic waves have not been explored as a tidal dissipation mechanism. In particular, stars with sufficiently strong magnetic fields could fully dissipate tidally excited waves, yielding the same tidal evolution as the previously studied “traveling wave regime.” Here, we evaluate the viability of this mechanism using stellar models of stars with convective cores (F-type stars in the mass range of 1.2–1.6 M ⊙), which were previously thought to be weakly tidally dissipative (due to the absence of nonlinear gravity-wave breaking). The criterion for wave conversion to operate is evaluated for each stellar mass using the properties of each star’s interior along with estimates of the magnetic field produced by a convective core dynamo under the assumption of equipartition between kinetic (convective) and magnetic energies. Our main result is that this previously unexplored source of efficient tidal dissipation can operate in stars within this mass range for significant fractions of their lifetimes. This tidal dissipation mechanism appears to be consistent with the observed inspiral of WASP-12b and more generally could play an important role in the orbital evolution of hot Jupiters—and to lower-mass ultra-short-period planets—orbiting F-type stars.

Optimal strategies for the exploration of near-by stars

In the past decade, the discovery of exoplanets has sparked new interests in the idea of interstellar travel and exploration. Despite various proposals for probe concepts and relevant technologies, there is a lack of extensive literature on viable exploration strategies for journeys beyond a single star system. Such exploration strategies might not only have implications on technology development strategies for achieving interstellar exploration but could also enrich existing models for galactic exploration feeding into solutions of the Fermi Paradox. This article presents optimal strategies for the exploration of a large number of near-by stars, using a dedicated, novel methodology, which sets it apart from existing literature: For the first time, the mission design problem of interstellar exploration is redefined as a bi-objective multi-vehicle open routing problem with profits. It is tackled by an adapted hybrid multi-objective genetic algorithm, which is further improved and modified according to the problem characteristics (e.g. large search space). The overall mission model assumes probes traveling on straight trajectories, utilizing flybys, and maintaining an average velocity of 10% of the speed of light. Surpassing prior research that typically relies on statistical models or restricted star data, the star models are founded on the second Gaia data release (Gaia DR2), which represents the most extensive star catalogue to the date of this study and is employed for the first time in the context of interstellar exploration. The resulting star model contains a maximum of 10,000 stars within a spherical region around Sol, covering a distance of 110 light years.It is found, that the number of explored stars J1 scales with mission duration J2 and probe number m according to J1∼J2m0.66, which provides an initial guidance for future interstellar mission design. Furthermore, the routes and selection of stars vary depending on the number of probes used: When conducting missions with a large number of probes, stars in close proximity to the Solar System are given more focus. On the other hand, missions with a small number of probes include more distant stars to facilitate shorter transfers along the route. Based on these findings, the following recommendations for interstellar exploration strategies can be drawn: When energy resources such as fuel reserves are scarce and the exploration mission is not limited to nearby stars, low probe numbers are more efficient. In contrast, high probe numbers enable faster exploration of nearby stars but involve less resource-efficient transfers, making them a suitable option for small, remotely propelled probe concepts. To address crowding effects in high probe number missions, swarm-based probe concepts are recommended based on the scaling law characteristics derived.

Measurements-to-body: 3D human body reshaping based on anthropometric measurements

Accurate 3D human models are useful for many applications in virtual fitting, ergonomics, film and television, and video games. However, due to the limitations of 3D scanners and body privacy, creating a virtual human body that accurately represents a specific human body is challenging. Therefore, reshaping 3D human bodies based on anthropometric measurements has received extensive attention. However, the existing methods have some drawbacks, such as the inability of the reshaped body to change its posture, the lack of a good link between the real and virtual measurements, and unreasonable anthropometry definitions. In this paper, we propose a new framework for reshaping the 3D human body using five easily available measurements: height, weight, chest, waist, and hip. First, the STAR model was used to fit the SPRING dataset to obtain the SPRING-fitted dataset, where the shape parameters of the STAR model are used to characterize each 3D human body. Second, optimizing the virtual measurement algorithm constructed a good link between real and virtual measurements. Then, the measurements of the human bodies in the SPRING-fitted dataset were extracted. Finally, the semantic reshaping of the 3D human body can be achieved by constructing a neural network model that uses the five measurements to predict 20 shape parameters. The results show that the human body reconstructed by our method can keep its size close to the real human body and conform to the shape of the real human body. Thus, it can meet the needs of the garment industry. In addition, the reshaped human body can be adjusted to different postures, which is beneficial to virtual fitting.

Realistic compact objects in the f(R, T) gravity in the background of polytropic and barotropic gas models

The f(R, T) gravity in the background of the polytropic and barotropic fluid has been investigated in this work. We have selected the TOV equation to determine the internal spacetime of a spherically symmetric galactic object. With the use of the Einstein equation, we have selected KB-spacetime to calculate the mass, compactness, and surface redshift of a spherically symmetric body. Explicit conditions for model parameters have been constructed for the boundary conditions of the interior and exterior spacetime, and the Schwarzschild solution has been employed in the modified f(R, T) gravity theory to evaluate different matching criteria. An increasing pattern in compactness with respect to the different radii is evident in the graphical representation of the compactness evolution for each of the individual star models. After selecting a non-vacuum field equation for higher order curvature, we reformulated f(R, T) for R and T. As a result, the tangential pressure, radial pressure, and matter density have all been calculated. According to the study, as the radius goes to infinity, the tangential and radial pressures display asymptotic flatness and converge to zero. Polytropic and barotropic gas EoS have been adopted since the star model confronts the presence of an isotropic fluid backdrop. It has been noted that in a polytropic background, density and pressure increase with distance from the star’s core, but in a barotropic background, the pressure exhibits an ascending pattern as a function of radius.

Dark energy stars in the context of black holes — The physical profiles

The dark energy star is a hypothetical model proposed as an alternative to address problems related to the structure of black holes (BHs), such as the presence of singularities. While dark energy star models have been previously explored, their application to BHs remains unexplored. This paper aims to investigate the concept of dark energy stars and compare their properties to BHs. The primary objective is to explore the physical profiles of dark energy stars and evaluate their similarity to the physical properties of BHs described by the Schwarzschild solution. To achieve this, specific properties of the dark energy star models need to be satisfied in the context of BHs, and their physical profiles are studied. The metric function [Formula: see text] proposed by M. R. Finch and J. E. F. Skea [Class. Quantum Grav. 6, 467 (1989)], as adopted by A. Banerjee, M. K. Jasim and A. Pradhan [Mod. Phys. Lett. A 35, 2050071 (2020), arXiv:1911.09546 [gr-qc]], is used and parametrized, making it close to BH spacetimes. The findings show that the model exhibits properties similar to BHs in terms of the stellar radius, compactness, surface redshift, and nature of gravity. Specifically, the dark energy star model behaves like BHs with a dark energy parameter [Formula: see text], satisfying all energy conditions. However, it should be noted that the investigation is limited to static spherically symmetric cases and further studies are required to explore the model in rotating cases. Overall, this study sheds light on the potential of dark energy star models in explaining BH properties and presents promising avenues for further research in understanding the nature of BHs and dark energy.

Charged anisotropic fluid sphere in [formula omitted] gravity satisfying Vaidya - Tikekar metric

In this paper, we study the properties of electrically charged anisotropic and spherically symmetric compact stars in f(Q) gravity theory. The field equations have been solved using the MIT-Bag Equation of State (EoS) along with the Vaidya–Tikekar potential. However, the specific form of charge E2(r)=q0L2r2(1+Lr2)2 has been used to study the charged compact star model. The interior charge anisotropic solution has been matched with the charged Schwarzchild-(Anti)-de-Sitter metric. In particular, this study has been conducted on different compact stars viz, EXO 1785-248, PSR J1614-2230, PSR J0740+620 and SMC X-1. The mass–radius ratio of these compact stars has been predicted, and the physical viability of the model has been checked through the behaviour of causality condition, matter variables, energy constraints, modified TOV equation, and adiabatic index of the star. In conclusion, we observe a well-behaved model of a compact star in f(Q) gravity with charged matter distribution.

Excited Dirac stars with higher azimuthal harmonic index

In this paper, we investigate the properties of the first excited state Dirac stars (DSs) with higher azimuthal harmonic index (specifically, the azimuthal harmonic indexes mD = 3/2, 5/2, 7/2), as well as the relationship between the ADM mass and angular momentum of Dirac stars with respect to frequency. Moreover, we find that the ergospheres of DSs appear at lower spinor field frequencies, and both the ergospheres and the distribution of the spinor field functions are asymmetric about the equatorial plane. Furthermore, we introduce the ground state scalar field and examine its impact on this system, which is known as the multi-state Dirac-boson stars (DBSs) model. We show various types of solution families for DBSs under both synchronized frequency ω and nonsynchronized frequencies and find that similar to DSs, the spinor field and the ergospheres of DBSs are also asymmetric about the equatorial plane, but the ergospheres appear at higher spinor field frequencies.

A Geometric Neutron Star Model of Repeating and Nonrepeating Fast Radio Bursts

Fast radio bursts (FRBs) are millisecond-duration extragalactic radio transients. They fall into the categories of repeaters and apparent nonrepeaters. However, such a classification causes a lack of motivation to investigate the physical picture. Here, we propose a unified geometric model to distinguish between repeaters and apparent nonrepeaters, in which the quasi-tangential (QT) propagation effect within the magnetosphere of a neutron star is considered. In this model, apparent nonrepeaters arise from sources whose emitting region has a smaller impact angle with respect to the magnetic axis, while repeaters come from sources whose emitting region has a larger impact angle. The observational discriminant polarization properties between repeaters and apparent nonrepeaters are an important clue for verifying this unified geometric model since the polarization is sensitive to the QT propagation effect. Moreover, our model effectively explains all of the other discriminant properties, including bandwidth, duration, peak luminosity, energy, brightness temperature, time–frequency downward drifting, and repetition rate, providing compelling evidence for the magnetospheric origin of FRBs.

Impact of different approaches to computing rotating stellar models

Context. The physics of stellar rotation plays a crucial role in the evolution of stars, in their final fates, and for the properties of compact remnants. Aims. Diverse approaches have been adopted to incorporate the effects of rotation in stellar evolution models. This study seeks to explore the consequences that these various prescriptions for rotation have for the essential outputs of massive star models. Methods. We computed a grid of 15 and 60 M⊙ stellar evolution models with the Geneva Stellar Evolution Code that accounted for both hydrodynamical and magnetic instabilities induced by rotation. Results. In the 15 and 60 M⊙ models, the choice of the vertical and horizontal diffusion coefficients for the nonmagnetic models strongly impacts the evolution of the chemical structure, but has a weak impact on the angular momentum transport and the rotational velocity of the core. In the 15 M⊙ models, the choice of the diffusion coefficient impacts the convective core size during the core H-burning phase, regardless of whether the model begins core He-burning as a blue or red supergiant and regardless of the core mass at the end of He-burning. In the 60 M⊙ models, the evolution is dominated by mass loss and is less strongly affected by the choice of the diffusion coefficient. In the magnetic models, magnetic instability dominates the angular momentum transport, and these models are found to be less strongly mixed than their rotating nonmagnetic counterparts. Conclusions. Stellar models with the same initial mass, chemical composition, and rotation may exhibit diverse characteristics depending on the physics applied. By conducting thorough comparisons with observational features, we can ascertain which method(s) produce the most accurate results in different cases.

Finch–Skea Stellar structures obeying Karmarkar condition in modified [formula omitted] gravity

The current research addresses the composition and modeling of compact dense astrophysical objects in a renowned modified gravity namely f(G) theory, where G denotes the Gauss Bonnet term. In this respect, a family of anisotropic spherically symmetric relativistic solutions of compact objects in hydrostatic equilibrium are obtained. To solve the corresponding modified field equations, we employ the well-famed Karmarkar condition along with the Finch–Skea ansatz for one of the metric potentials. By taking the outer area as Schwarzschild metric, we expand the boundary conditions for spacetime continuity. The unknown constants, appearing in the solutions, are then assessed by using data (mass and radius) of some realistic compact stars namely SMCX-1, 4U 1728-34, 4U 1538-52, EXO 1785-248, SAXJ 1808.4-3658. Furthermore, a graphical analysis is performed for examining the physical behavior of these compact star models. We discuss several physical properties of anisotropic compact stellar structures and explore viability as well as stability of the proposed models. It is concluded that features of established models are in good agreement with the reality of compact stellar structures in the background of f(G) theory.

Dirac stars in wormhole spacetime

In this paper, we study the spherically symmetric Dirac star model in the presence of a phantom field, obtaining a traversable wormhole solution in non-trivial topological spacetime. This solution exhibits asymmetry in both the field configuration and the metric and possesses a finite ADM mass M and Noether charge Q. Furthermore, due to a wormhole at the center, this solution exhibits many differences from the Dirac star under trivial spacetime. Notably, when the wormhole throat size is small, our numerical calculations indicate the emergence of an extremely approximate black hole solution on one side of the wormhole spacetime, a phenomenon unexplored. At this time, the Kretschmann scalar near the throat tends to infinity, indicating the wormhole becomes untraversable.

Risk of human leptospirosis in Colombia: spatiotemporal analysis and related hydroclimatic factors.

Leptospirosis is an endemic zoonosis in tropical areas that is mainly related to rural activities; nevertheless, human leptospirosis (HL) outbreaks differ among regions. In Colombia, HL notifications are mandatory. Our objective was to determine the spatiotemporal distribution of HL in Colombia during 2007-2018 and its relationship with the main hydroclimatic variables. We determined the estimated incidence and lethality of HL according to department and year. The Bayesian spatiotemporal analysis of an autoregressive model (STAR) model included HL cases and hydroclimatic factors (average temperature, rainfall and relative humidity) for quarterly periods. During the study period, 10 586 HL cases were registered (estimated incidence: 1.75 cases x 105) and 243 deaths by HL (lethality 2.3%). The STAR model found association of HL risk with temperature (RR:6.80; 95% CI 3.57 to 12.48) and space. Quindío and three other Amazonian departments (Guainía, Guaviare and Putumayo) had a positive relationship with a significant number of HL cases, adjusted for quarterly precipitation and humidity. Spatial analysis showed a high risk of HL in departments of the western Andean Colombian regions. By contrast, in the spatiotemporal model, a higher HL risk was associated with temperature and departments of the North Colombian Amazon regions and Quindío in the Colombian Andean region.

How to increase business opportunities and entrepreneurial capacity of developing universities: Star Model

Higher education institutions (universities) make a significant contribution to the economy and social life of a country. For this reason, the interaction between universities, industry and society is important for countries. Universities need to get rid of the classical university concept and begin to take a role of entrepreneurial universities and transfer the acquired knowledge to industry and society. Thus, an entrepreneurial university can ensure the production of new information and technologies, as well as influence the use of acquired knowledge in production. The next generation of entrepreneurial universities not only need to develop their core competencies, but also have a domino effect on the creation and dissemination of new knowledge. This paper describes the interactions of relevant stakeholders necessary for the effective and efficient use of a country’s resources. These stakeholders are entrepreneurial universities as sources of scientific knowledge; production sector representing business; the government, which develops policies for universities and industry; non-governmental organizations and professional associations that support education and science. Integrating these five key stakeholders creates synergy. The authors developed a model called the Star Model because of its five-tailed shape. The results of the study can be useful to universities, business, government, non-governmental organizations, and professional associations to form interactions and develop policies and strategies for their development and the development of the economy.

Analysing radio pulsar timing noise with a Kalman filter: a demonstration involving PSR J1359−6038

ABSTRACT In the standard two-component crust-superfluid model of a neutron star, timing noise can arise when the two components are perturbed by stochastic torques. Here it is demonstrated how to analyse fluctuations in radio pulse times of arrival with a Kalman filter to measure physical properties of the two-component model, including the crust-superfluid coupling time-scale and the variances of the crust and superfluid torques. The analysis technique, validated previously on synthetic data, is applied to observations with the Molonglo Observatory Synthesis Telescope of the representative pulsar PSR J1359−6038. It is shown that the two-component model is preferred to a one-component model, with log Bayes factor 6.81 ± 0.02. The coupling time-scale and the torque variances on the crust and superfluid are measured with 90 per cent confidence to be $10^{7.1^{+0.8}_{-0.5}}$$\rm {s}$ and $10^{-24.0^{+0.4}_{-5.6}}$$\rm {rad^2~s^{-3}}$ and $10^{-21.7^{+3.5}_{-0.9}}$$\rm {rad^2~s^{-3}}$, respectively.