330 research outputs found
Equation-of-state-independent relations in neutron stars
Neutron stars are extremely relativistic objects which abound in our universe
and yet are poorly understood, due to the high uncertainty on how matter
behaves in the extreme conditions which prevail in the stellar core. It has
recently been pointed out that the moment of inertia I, the Love number lambda
and the spin-induced quadrupole moment Q of an isolated neutron star, are
related through functions which are practically independent of the equation of
state. These surprising universal I-lambda-Q relations pave the way for a
better understanding of neutron stars, most notably via gravitational-wave
emission. Gravitational-wave observations will probe highly-dynamical binaries
and it is important to understand whether the universality of the I-lambda-Q
relations survives strong-field and finite-size effects. We apply a
Post-Newtonian-Affine approach to model tidal deformations in compact binaries
and show that the I-lambda relation depends on the inspiral frequency, but is
insensitive to the equation of state. We provide a fit for the universal
relation, which is valid up to a gravitational wave frequency of ~900 Hz and
accurate to within a few percent. Our results strengthen the universality of
I-lambda-Q relations, and are relevant for gravitational-wave observations with
advanced ground-based interferometers. We also discuss the possibility of using
the Love-compactness relation to measure the neutron-star radius with an
uncertainty of about 10% or smaller from gravitational-wave observations.Comment: 5 pages, 2 figures, 2 table
Probing Planckian corrections at the horizon scale with LISA binaries
Several quantum-gravity models of compact objects predict microscopic or even
Planckian corrections at the horizon scale. We explore the possibility of
measuring two model-independent, smoking-gun effects of these corrections in
the gravitational waveform of a compact binary, namely the absence of tidal
heating and the presence of tidal deformability. For events detectable by the
future space-based interferometer LISA, we show that the effect of tidal
heating dominates and allows one to constrain putative corrections down to the
Planck scale. The measurement of the tidal Love numbers with LISA is more
challenging but, in optimistic scenarios, it allows to constrain the
compactness of a supermassive exotic compact object down to the Planck scale.
Our analysis suggests that highly-spinning, supermassive binaries at 1-20 Gpc
provide unparalleled tests of quantum-gravity effects at the horizon scale.Comment: v4: matches version in Phys. Rev. Lett; Editors' Suggestio
From micro to macro and back: probing near-horizon quantum structures with gravitational waves
Supermassive binaries detectable by the future space gravitational-wave
interferometer LISA might allow to distinguish black holes from ultracompact
horizonless objects, even when the latter are motivated by quantum-gravity
considerations. We show that a measurement of very small tidal Love numbers at
the level of accuracy (as achievable with "golden binaries") may also
allow to distinguish between different models of these exotic compact objects,
even when taking into account an intrinsic uncertainty in the object radius
putatively due to quantum mechanics. We argue that there is no conceptual
obstacle in performing these measurements, the main challenge remains the
detectability of small tidal effects and an accurate waveform modelling. Our
analysis uses only coordinate-independent quantities related to the proper
radial distance and the total mass of the object.Comment: Minor changes to match the version published on CQ
Gravitational radiation from collisions at the speed of light: a massless particle falling into a Schwarzschild black hole
We compute spectra, waveforms, angular distribution and total gravitational
energy of the gravitiational radiation emitted during the radial infall of a
massless particle into a Schwarzschild black hole. Our fully relativistic
approach shows that (i) less than 50% of the total energy radiated to infinity
is carried by quadrupole waves, (ii) the spectra is flat, and (iii) the zero
frequency limit agrees extremely well with a prediction by Smarr. This process
may be looked at as the limiting case of collisions between massive particles
traveling at nearly the speed of light, by identifying the energy of the
massless particle with , being the mass of the test particle
and the Lorentz boost parameter. We comment on the implications for
the two black hole collision at nearly the speed of light process, where we
obtain a 13.3% wave generation efficiency, and compare our results with
previous results by D'Eath and Payne.Comment: 10 pages, 3 figures, published versio
Glassy materials for Silicon-based solar panels: present and future
About 2/3 of a commercial solar panel's weight is glass. This material should
provide mechanical, chemical, and UV protection, contributing to the device's
overall net energy production. Here we discuss some current trends in glassy
materials for Silicon photovoltaics. The search for environmentally friendly
glasses and new features such as anti-reflection, self-cleaning, and spectral
conversion is reviewed. A conceptual model to compare UV-blocking and spectral
converter materials is proposed, and the potential of these features to improve
solar power production and its sustainability are discussed.Comment: 47 pages, 4 figure
Tratado notarial e registral
Divulgação dos SUMÁRIOS das obras recentemente incorporadas ao acervo da Biblioteca Ministro Oscar Saraiva do STJ. Em respeito à Lei de Direitos Autorais, não disponibilizamos a obra na íntegra.Localização na estante: 347.961(81) K95
A simple HPLC method for the determination of halcinonide in lipid nanoparticles: development, validation, encapsulation efficiency, and in vitro drug permeation
Halcinonide is a high-potency topical glucocorticoid used for skin inflammation treatments that presents toxic systemic effects. A simple and quick analytical method to quantify the amount of halcinonide encapsulated into lipid nanoparticles, such as polymeric lipid-core nanoparticles and solid lipid nanoparticles, was developed and validated regarding the drug's encapsulation efficiency and in vitro permeation. The development and validation of the analytical method were carried out using the high performance liquid chromatography with the UV detection at 239 nm. The validation parameters were specificity, linearity, precision and accuracy, limits of detection and quantitation, and robustness. The method presented an isocratic flow rate of 1.0 mL.min-1, a mobile phase methanol:water (85:15 v/v), and a retention time of 4.21 min. The method was validated according to international and national regulations. The halcinonide encapsulation efficiency in nanoparticles was greater than 99% and the in vitro drug permeation study showed that less than 9% of the drug permeated through the membrane, indicating a nanoparticle reservoir effect, which can reduce the halcinonide's toxic systemic effects. These studies demonstrated the applicability of the developed and validated analytical method to quantify halcinonide in lipid nanoparticles
FE-SEM Evaluation of Dental Specimens Prepared by Different Methods for In Vitro Contamination
Objective. To evaluate through FE-SEM the cleanliness and dentinal alterations promoted by different methods of dental sample preparation. Methods. Twenty-five human single-rooted teeth were used. The teeth were cleaned and autoclaved in wet medium and randomly divided into 5 groups (n = 5), according to the preparation methods employed—control group: no solutions applied; group 1: cement removal and irrigation with 5.25% NaOCl + 17
% EDTA for 4 minutes each; group 2: 17% EDTA + 2.5% NaOCl (4 minutes ultrasonic bath); group 3: cement removal and 17% EDTA + 5.25% NaOCl + phosphate
buffer solution + distilled water (10 minutes ultrasonic); group 4: 17% EDTA + 5.25% NaOCl (3 minutes ultrasonic bath). Specimens were analyzed by field emission scanning electron microscope (FE-SEM), at 1500x magnification. Data were submitted to qualitative analysis according to a scoring system and submitted to Kruskal-Wallis test. Results. In ascending order, as to bind parameters, (i) cleanliness: control, group 2, group 3, group 5, and group 4, (ii) dentinal alterations: group 1, group 5, group 2, group 3, and group 4. Conclusion. The proposed protocol was suitable for subsequent microbiological contamination, because it showed less dentinal morphological alterations with increased removal of organic waste
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