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2025
The relativistic jets of gamma-ray bursts (GRBs) might be powered by a black-hole (BH) hyperaccretion system. The inherent asymmetry in these jets generates recoil forces, inducing oscillations and positional deviations of the BH from equilibrium. In this study, we explore the influence of different initial BH mass, spin, and mass accretion rate, as well as their evolutions on the dynamical properties of BH under the effect of asymmetric jets. Our results reveal that the initial mass and accretion rate significantly impact the BH’s acceleration, velocity, and displacement, while the different initial spin plays a negligible role in shaping the overall dynamical evolution. Additionally, we calculate the gravitational wave (GW) strains associated with the asymmetric jets, finding that the resulting GW signals are too weak to be detected, even for nearby GRBs. These findings provide critical insights into the dynamical response of BHs to asymmetric jets and the associated GW radiation, advancing our understanding of BH physics in GRBs.- Book : 11(2)
- Pub. Date : 2025
- Page : pp.43-43
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2025
Axion-like particles (ALPs) are hypothetical pseudoscalar bosons, natural in extensions of the Standard Model. Their interactions with ordinary matter and radiation are suppressed, making it challenging to detect them in laboratory experiments. However, these particles, produced within stellar interiors, can provide an additional mechanism for energy loss, potentially influencing stellar evolution. Prominent methods for searching for such effects involve measuring the properties of red giants and helium-burning stars in globular clusters (GCs). Here we use published catalogs of stars selected as members of seven GCs on the basis of parallaxes and proper motions measured by Gaia (Data Release 3). Making use of previously derived theoretical relations and the new data, we find the upper limit on the ALP-electron coupling, g
ae
< 5.2 × 10–14 (95% CL), and an indication (3.3σ) to nonzero ALP-photon coupling, g
aγ =
$$(6.5_{{ - 1.3}}^{{ + 1.1}})$$
× 10–11 GeV–1. Given the precision of contemporary observational data, it is imperative to refine ALP constraints through more sophisticated analyses, which will be explored in detail elsewhere.- Book : ()
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2025
- Book : 42()
- Pub. Date : 2025
- Page : pp.101880-101880
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2025
Lycopene which is a carotenoid found in tomatoes and other red and orange fruits, has shown benefits in dermatology and photoprotection. It is a powerful antioxidant and has been proposed as a potential ingredient for sunscreen preparations designed to reduce UV-induced skin damage. The review will discuss the available data regarding the activity of lycopene in sunscreen formulations, mainly in relation to mechanism of action, performance.
The photoprotective properties of lycopene depend on its free radical scavenger activity and capacity for neutralizing ROS, produced upon UV activation. ROS plays a key role in damage to structures within skin through DNA mutations, inflammation, photo-ageing, and enhanced risk for skin cancer. Lycopene has antioxidant properties and the capacity to absorb UV radiation in the UVA and UVB spectrum, making it an interesting ingredient in fortified sunscreens. Several in vitro and in vivo studies have shown that lycopene can significantly reduce erythema, DNA damage, and oxidative stress after UV exposure, making it an interesting potential preventive agent against both acute sunburn and chronic, cumulative damage associated with long-term skin ageing.
Lycopene remains a highly promising natural photoprotective agent; however, additional clinical studies and safety assessments must be undertaken to establish the best use of lycopene as a participant in the composition of sunscreen ingredients- Book : ()
- Pub. Date : 2025
- Page : pp.618-626
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2025
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2025
Abstract
Terrestrial exoplanets around M- and K-type stars are important targets for atmospheric characterization. Such planets are likely tidally locked with the order of spin–orbit resonances (SORs) depending on eccentricity. We explore the impact of SORs on 3D atmospheric dynamics and chemistry, employing a 3D coupled climate-chemistry model to simulate Proxima Centauri b in 1:1 and 3:2 SORs. For a 1:1 SOR, Proxima Centauri b is in the Rhines rotator circulation regime with dominant zonal gradients (global mean surface temperature 229 K). An eccentric 3:2 SOR warms Proxima Centauri b to 262 K with gradients in the meridional direction. We show how a complex interplay between stellar radiation, orbit, atmospheric circulation, and (photo)chemistry determines the 3D ozone distribution. Spatial variations in ozone column densities align with the temperature distribution and are driven by stratospheric circulation mechanisms. Proxima Centauri b in a 3:2 SOR demonstrates additional atmospheric variability, including daytime–nighttime cycles in water vapor of +55% to −34% and ozone (±5.2%) column densities and periastron–apastron water vapor cycles of +17% to −10%. Synthetic emission spectra for the spectral range of the Large Interferometer For Exoplanets fluctuate by up to 36 ppm with the orbital phase angle for a 1:1 SOR due to 3D spatial and temporal asymmetries. The homogeneous atmosphere for the 3:2 SOR results in relatively constant emission spectra and provides an observational discriminant from the 1:1 SOR. Our work emphasizes the importance of understanding the 3D nature of exoplanet atmospheres and associated spectral variations to determine habitability and interpret atmospheric spectra.- Book : 6(1)
- Pub. Date : 2025
- Page : pp.5-5
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