Gravitational Radiation Instability in Hot Young Neutron Stars

We show that gravitational radiation drives an instability in hot young rapidly rotating neutron stars. This instability occurs primarily in the l=2 r-mode and will carry away most of the angular momentum of a rapidly rotating star by gravitational radiation. On the timescale needed to cool a young neutron star to about T=10^9 K (about one year) this instability can reduce the rotation rate of a rapidly rotating star to about 0.076\Omega_K, where \Omega_K is the Keplerian angular velocity where mass shedding occurs. In older colder neutron stars this instability is suppressed by viscous effects, allowing older stars to be spun up by accretion to larger angular velocities.Comment: 4 Pages, 2 Figure

The Effect of Neutron Star Binding Energy on Gravitational-Radiation-Driven Mass-Transfer Binaries

In a relativistic model of a neutron star, the star's mass is less than the mass of the individual component baryons. This is due to the fact that the star's negative binding energy makes a contribution to the star's total energy and its mass. A consequence of this relativistic mass deficit is that a neutron star that is accreting matter increases its mass at a rate which is slower than the mass of a baryon times the rate that baryons are accreted. This difference in the rate of change of the masses has a simple relation with the star's gravitational redshift. We show that this effect has the potential to be observed in binaries where the mass transfer is driven by angular momentum losses from the gravitational radiation emitted by the binary motion.Comment: 9 pages, 3 figures, accepted by Ap

Overview of BIM integration into the Construction Sector in European Member States and European Union Acquis

The amount of information involved in any construction project and the necessity of control of time, cost and waste, has established Building Information Modelling (BIM) as an integral part of construction sector towards achieving adequate communication of information among various parties involved in construction projects. Moreover, it can be considered as a valuable tool for the optimum selection of materials, systems and design decisions, regarding not only the improve of a structure’s performance, but also in terms of reducing its carbon footprint during its life cycle. The study attempts to present the integration of BIM into the national legislation of European Member States, with a special focus on the energy related aspects of BIM analysis. This study performs an overview of the introduction of BIM into different aspects and requirements of the EU Member States building practices, through a comprehensive literature and legislation review of relative legislative documents of the construction sector. According to the findings of this overview study, the concept of BIM has already been incorporated in many aspects of the Acquis of EU Member States, which is recognized as a valuable tool to be exploited by the construction sector, however there is still room for development in this area. The study has revealed that especially in the energy assessment of the built environment, BIM applications are still lacking from the European Legislation. Examples and good practices of employing BIM for the implementation of the European Energy targets in the building sector are also presented and discussed. The findings of this study aim to shed light on the needs and requirements in the field of BIM development for the construction sector, as well as to indicate gaps and weaknesses of the European Member States Acquis towards harmonizing with BIM practices

Skin color influences transcutaneous bilirubin measurements:a systematic in vitro evaluation

Objective: Concerns have been raised about the effect of skin color on the accuracy of transcutaneous bilirubin (TcB) measurements, a widely used method for hyperbilirubinemia diagnosis in newborns. Literature is inconclusive, with both reported under- and overestimations of the TcB with increasing skin pigmentation. Therefore, the influence of skin color on TcB measurements was systematically evaluated in a controlled, in vitro setting. Methods: A bilirubin meter (JM-105) was evaluated on layered phantoms that mimic neonatal skin with varying dermal bilirubin concentrations (0–250 µmol/L) and varying epidermal melanosome volume fractions (0–40%; light-dark skin color). Results: TcB measurements were influenced by skin pigmentation. Larger mimicked melanosome volume fractions and higher bilirubin levels led to larger underestimations of the measured TcB, compared to an unpigmented epidermis. In the in vitro setting of this study, these underestimations amounted to 26–132 µmol/L at a TcB level of 250 µmol/L. Conclusion: This in vitro study provides insight into the effect of skin color on TcB measurements: the TcB is underestimated as skin pigmentation increases and this effect becomes more pronounced at higher bilirubin levels. Our results highlight the need for improved TcB meter design and cautious interpretation of TcB readings on newborns with dark skin. Impact: Key message: Skin color influences transcutaneous bilirubin measurements: the darker the skin, the larger the underestimation. What this study adds to existing literature: Existing literature is inconclusive regarding the influence of skin color on transcutaneous bilirubin measurements. This study systematically evaluates and clarifies the influence of skin color on transcutaneous bilirubin measurements in a controlled, in vitro setting. Impact: This study aids to better interpret the measured TcB level in patients with varying skin colors, and is particularly important when using TcB meters on patients with dark skin colors.</p

Applications of natural, semi-synthetic, and synthetic polymers in cosmetic formulations

Cosmetics composed of synthetic and/or semi-synthetic polymers, associated or not with natural polymers, exhibit a dashing design, with thermal and chemo-sensitive properties. Cosmetic polymers are also used for the preparation of nanoparticles for the delivery of, e.g., fragrances, with the purpose to modify their release profile and also reducing the risk of evaporation. Besides, other cosmetically active nutrients, dermal permeation enhancers, have also been loaded into nanoparticles to improve their bioactivities on the skin. The use of natural polymers in cosmetic formulations is of particular relevance because of their biocompatible, safe, and eco-friendly character. These formulations are highly attractive and marketable to consumers, and are suitable for a plethora of applications, including make-up, skin, and hair care, and as modifiers and stabilizers. In this review, natural synthetic, semi-synthetic, and synthetic polymers are discussed considering their properties for cosmetic applications. Their uses in conventional and novel formulations are also presented.This research was funded by Banco do Nordeste (FUNDECI 2017.0016), Coordenação Aperfeiçoamento de Pessoal de Nível Superior (CAPES) and Fundação de Amparo à Pesquisa do Estado de Sergipe (FAPITEC)(PROCESSO: 88887.159533/2017-00), Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq301964/2019-0, and Chamada CNPq nº01/2019) and by Portuguese Science and Technology Foundation, Ministryof Science and Education (FCT/MEC) through national funds, and co-financed by FEDER, under the project reference UIDB/04469/2020 (strategic fund), co-financed by FEDER, under the Partnership Agreement PT2020info:eu-repo/semantics/publishedVersio

Cosmological Models in Two Spacetime Dimensions

Various physical properties of cosmological models in (1+1) dimensions are investigated. We demonstrate how a hot big bang and a hot big crunch can arise in some models. In particular, we examine why particle horizons do not occur in matter and radiation models. We also discuss under what circumstances exponential inflation and matter/radiation decoupling can happen. Finally, without assuming any particular equation of state, we show that physical singularities can occur in both untilted and tilted universe models if certain assumptions are satisfied, similar to the (3+1)-dimensional cases.Comment: 22 pgs., 2 figs. (available on request) (revised version contains `paper.tex' macro file which was omitted in earlier version

Exact Solution for the Metric and the Motion of Two Bodies in (1+1) Dimensional Gravity

We present the exact solution of two-body motion in (1+1) dimensional dilaton gravity by solving the constraint equations in the canonical formalism. The determining equation of the Hamiltonian is derived in a transcendental form and the Hamiltonian is expressed for the system of two identical particles in terms of the Lambert $W$ function. The $W$ function has two real branches which join smoothly onto each other and the Hamiltonian on the principal branch reduces to the Newtonian limit for small coupling constant. On the other branch the Hamiltonian yields a new set of motions which can not be understood as relativistically correcting the Newtonian motion. The explicit trajectory in the phase space $(r, p)$ is illustrated for various values of the energy. The analysis is extended to the case of unequal masses. The full expression of metric tensor is given and the consistency between the solution of the metric and the equations of motion is rigorously proved.Comment: 34 pages, LaTeX, 16 figure

Exact Black Hole and Cosmological Solutions in a Two-Dimensional Dilaton-Spectator Theory of Gravity

Exact black hole and cosmological solutions are obtained for a special two-dimensional dilaton-spectator ($\phi-\psi$) theory of gravity. We show how in this context any desired spacetime behaviour can be determined by an appropriate choice of a dilaton potential function $V(\phi)$ and a ``coupling function'' $l(\phi)$ in the action. We illustrate several black hole solutions as examples. In particular, asymptotically flat double- and multiple- horizon black hole solutions are obtained. One solution bears an interesting resemblance to the $2D$ string-theoretic black hole and contains the same thermodynamic properties; another resembles the $4D$ Reissner-Nordstrom solution. We find two characteristic features of all the black hole solutions. First the coupling constants in $l(\phi)$ must be set equal to constants of integration (typically the mass). Second, the spectator field $\psi$ and its derivative $\psi^{'}$ both diverge at any event horizon. A test particle with ``spectator charge" ({\it i.e.} one coupled either to $\psi$ or $\psi^{'}$), will therefore encounter an infinite tidal force at the horizon or an ``infinite potential barrier'' located outside the horizon respectively. We also compute the Hawking temperature and entropy for our solutions. In $2D$ $FRW$ cosmology, two non-singular solutions which resemble two exact solutions in $4D$ string-motivated cosmology are obtained. In addition, we construct a singular model which describes the $4D$ standard non-inflationary big bang cosmology ($big-bang\rightarrow radiation\rightarrow dust$). Motivated by the similaritiesbetween $2D$ and $4D$ gravitational field equations in $FRW$ cosmology, we briefly discuss a special $4D$ dilaton-spectator action constructed from the bosonic part of the low energy heterotic string action andComment: 34 pgs. Plain Tex, revised version contains some clarifying comments concerning the relationship between the constants of integration and the coupling constants