Hasil untuk "gr-qc"

T. G. McWilliams, A. Prescott, L. Montava-Garriga et al.

Summary Dysregulated mitophagy has been linked to Parkinson's disease (PD) due to the role of PTEN-induced kinase 1 (PINK1) in mediating depolarization-induced mitophagy in vitro. Elegant mouse reporters have revealed the pervasive nature of basal mitophagy in vivo, yet the role of PINK1 and tissue metabolic context remains unknown. Using mito-QC, we investigated the contribution of PINK1 to mitophagy in metabolically active tissues. We observed a high degree of mitophagy in neural cells, including PD-relevant mesencephalic dopaminergic neurons and microglia. In all tissues apart from pancreatic islets, loss of Pink1 did not influence basal mitophagy, despite disrupting depolarization-induced Parkin activation. Our findings provide the first in vivo evidence that PINK1 is detectable at basal levels and that basal mammalian mitophagy occurs independently of PINK1. This suggests multiple, yet-to-be-discovered pathways orchestrating mammalian mitochondrial integrity in a context-dependent fashion, and this has profound implications for our molecular understanding of vertebrate mitophagy.

T. Winkler, F. Day, Damien C. Croteau-Chonka et al.

P. Tewarie, L. Balk, F. Costello et al.

Background Retinal optical coherence tomography (OCT) is an imaging biomarker for neurodegeneration in multiple sclerosis (MS). In order to become validated as an outcome measure in multicenter studies, reliable quality control (QC) criteria with high inter-rater agreement are required. Methods/Principal Findings A prospective multicentre study on developing consensus QC criteria for retinal OCT in MS: (1) a literature review on OCT QC criteria; (2) application of these QC criteria to a training set of 101 retinal OCT scans from patients with MS; (3) kappa statistics for inter-rater agreement; (4) identification reasons for inter-rater disagreement; (5) development of new consensus QC criteria; (6) testing of the new QC criteria on the training set and (7) prospective validation on a new set of 159 OCT scans from patients with MS. The inter-rater agreement for acceptable scans among OCT readers (n = 3) was moderate (kappa 0·45) based on the non-validated QC criteria which were entirely based on the ophthalmological literature. A new set of QC criteria was developed based on recognition of: (O) obvious problems, (S) poor signal strength, (C) centration of scan, (A) algorithm failure, (R) retinal pathology other than MS related, (I) illumination and (B) beam placement. Adhering to these OSCAR-IB QC criteria increased the inter-rater agreement to kappa from moderate to substantial (0.61 training set and 0.61 prospective validation). Conclusions This study presents the first validated consensus QC criteria for retinal OCT reading in MS. The high inter-rater agreement suggests the OSCAR-IB QC criteria to be considered in the context of multicentre studies and trials in MS.

M. Bastiani, M. Cottaar, S. Fitzgibbon et al.

&NA; Diffusion MRI data can be affected by hardware and subject‐related artefacts that can adversely affect downstream analyses. Therefore, automated quality control (QC) is of great importance, especially in large population studies where visual QC is not practical. In this work, we introduce an automated diffusion MRI QC framework for single subject and group studies. The QC is based on a comprehensive, non‐parametric approach for movement and distortion correction: FSL EDDY, which allows us to extract a rich set of QC metrics that are both sensitive and specific to different types of artefacts. Two different tools are presented: QUAD (QUality Assessment for DMRI), for single subject QC and SQUAD (Study‐wise QUality Assessment for DMRI), which is designed to enable group QC and facilitate cross‐studies harmonisation efforts. HighlightsTwo tools to automatically perform QC of diffusion MRI data.Automated generation of single subject reports for visual inspection and database.Group databases and reports allow to compare subjects within and between studies.Categorical and continuous variables can be used to update the reports.

Gregory Jarequi, Soumodeep Mitra, Varun Vaidya

We apply the point particle EFT approach to a compact star to systematically compute dynamical tidal love numbers for various non-rotating compact objects, extending the treatment of {arXiv:2307.10391[hep-th], arXiv:2407.08327 [gr-qc]}. We calculate the scattering amplitude in Black Hole Perturbation Theory(BPHT) for \textit{arbitrary} non-rotating compact stars using the Mano-Suzuki-Takasugi(MST) method with non zero surface reflectivity and match it with that obtained from point particle EFT order by order in the low frequency expansion. This sets up a systematic framework for extracting the static and dynamical tidal love numbers(TLNs) to any order in the multipole expansion. In this paper, we employ the technique to compute the Next-to-Next-to Leading Order TLN upto a universal constant and its Renormalization Group equation for non-viscous Neutron stars and Neutron stars admixed with Bosonic or Fermionic dark matter.

Shao-Wen Wei, Yu-Xiao Liu

The shadow of a black hole serves as a pristine window into the strong-gravity regime, with cuspy feature emerging as a smoking-gun signature of physics beyond the Kerr paradigm. In this paper, we extend the work of [arXiv:2601.15612 [gr-qc]] and study the detailed properties of the cuspy shadow by using the parametric expressions of the shadow boundary. From a topological perspective, we provide a rigorous topological classification of these shadows, categorizing them into distinct ``rectangular"and ``8-shape"topologies. Crucially, we establish a formal gravity/thermodynamics correspondence by mapping the cuspy shadow to the swallowtail behavior observed in thermodynamic free energy. We demonstrate that the self-intersection of the shadow boundary, marking a geometric phase transition, can be precisely determined through three independent but equivalently thermodynamic-like approaches. Furthermore, we analytically derive the critical exponents governing the emergence of these cusps, revealing that they are consistent with the mean-field universality class. Our results suggest that the observational features of black hole shadows are deeply rooted in the underlying gravitational thermodynamics, offering a novel framework to probe the fundamental nature of spacetime.

Mattia Damia Paciarini, Manuel Del Piano, S. Hohenegger et al.

Charged black holes arise as solutions of General Relativity (GR) coupled to Maxwell theory. As functions of the mass and charge, they can exhibit extremal behavior, in which case they are stable against thermal decay. (Quantum) corrections to GR are expected to alter the classical features of these objects, especially near extremality. To capture such effects in a model-independent way, we extend the Effective Metric Description (EMD) previously introduced in (Del Piano et al. in Phys Rev D 109(2):024045, 2024, https://doi.org/10.1103/PhysRevD.109.024045, arXiv:2307.13489 [gr-qc]; Eur Phys J C 84(12):1273, 2024, https://doi.org/10.1140/epjc/s10052-024-13609-5, arXiv:2403.12679 [gr-qc]) for spherically symmetric and static black holes. The EMD parametrizes deformations of the metric in terms of physical quantities, such as the radial spatial distance to the event horizon. While the latter is still viable for non-extremal charged black holes, we argue that the proper time of a free-falling observer is better suited in the extremal case: we derive the necessary conditions for the parameters of such an EMD for constructing a consistent space-time in the vicinity of the (extremal) horizon. Finally, we illustrate our framework through a concrete example, and mention implications of the Weak Gravity Conjecture on the effective metric parameters.

A. A. Araújo Filho, I. P. Lobo

The particle creation via quantum tunneling was recently calculated for the Schwarzschild non-commutative black hole solution in Ref. [Phys. Lett. B 848 (2024) 138335, e-Print: 2310.02445 [gr-qc]]. Nevertheless, it contains inconsistencies in the calculations that need to be properly corrected. In particular, the event horizon was incorrectly determined in that work, which affected all the subsequent calculations. Moreover, the same issue have been repeated elsewhere by the same authors in Refs. [1-4].

Shyam Das, M. Govender, Lipi Baskey

In the present work, we have studied the effect of equation of state (EOS henceforth) parameter on the complexity of static, self-gravitating systems. Utilizing the notion of complexity of static, spherically symmetric stars in general relativity as defined by Herrera (Phys Rev D 97:044010, 2018), we have investigated four types of EOS parameters of anisotropic stellar models. The models under consideration are the: (i) Sharma et al. configuration (arXiv:2402.05461 [gr-qc], 2024) assuming a linear EOS, (ii) Paul et al. compact object (Eur Phys J Plus 137:525, 2022) invoking a colour-flavour-locked EOS, (iii) Bhar anisotropic star (Astrophys Space Sci 359:41, 2015) employing a Chaplygin EOS and (iv) Sharma and Ratanpal stellar object (Int J Mod Phys D 22(13):1350074, 2013) assuming a quadratic EOS. All of these models share the Finch–Skea (FS) geometry for the interior spacetime. Our work shows that the complexity factor is strengthened as the EOS parameters increase for each of the equation of states under investigation.

Paul Richmond, C. Papageorgakis, V. Niarchos et al.

We present specialized large language models (LLMs) for theoretical high-energy physics, obtained as 20 fine-tuned variants of the 8 billion parameter Llama-3.1 model. Each variant was trained on arXiv abstracts (through August 2024) from different combinations of hep-th, hep-ph and gr-qc. For a comparative study, we also trained models on datasets that contained abstracts from disparate fields such as the q-bio and cs categories. All models were fine-tuned using two distinct low-rank adaptation fine-tuning approaches and varying dataset sizes, and outperformed the base model on hep-th abstract completion tasks. We compare performance against leading commercial LLMs (ChatGPT, Claude, Gemini, DeepSeek) and derive insights for further developing specialized language models for high-energy theoretical physics.

A. A. Araújo Filho, I. P. Lobo

A recent study [Annals Phys. 455 (2023) 169394, e-Print: 2204.01901 [gr-qc]] examined the thermodynamic behavior of an axially symmetric black hole within a non-commutative framework that mimics the effect of an angular momentum. However, the analysis presents notable computational inconsistencies. In that analysis, the event horizon was miscalculated, and this error propagated through and compromised all subsequent results. In addition, an incorrect definition of surface gravity was used -- the spherically symmetric case was invoked for an axially symmetric spacetime -- rendering the thermodynamic results invalid. In other words, all the results presented in the paper require a thorough reexamination.

Soumya Chakrabarti

We discuss the notion of generating a cosmic inflation without any big bang singularity. It has recently been proved by Good and Linder (arXiv:2503.02380 [gr-qc]) that such an expansion of the universe can be driven by quantum fluctuations embedded in vacuum. The rate of expansion is guided by a cosmological sum rule defined through the Schwarzian derivative. We explore the thermodynamic roots of Schwarzian and connect it with the surface gravity associated with an apparent horizon. In General Relativity the cosmological sum rule can be enforced only if the early universe is a Milne vacuum. We show that this restriction can be removed by considering an entropic source term in the Einstein–Hilbert action.

D. Bini, T. Damour, A. Geralico

Starting from the recently derived conservative tail-of-tail action [D. Bini and T. Damour, arXiv:2504.20204 [hep-th]] we compute several dynamical observables of binary systems (Delaunay Hamiltonian, scattering angle), at the 6.5 post-Newtonian accuracy and up to the 8th post-Minkowskian order. We find perfect agreement with previous self-force results, and (when inserting a recent high-post-Newtonian order derivation of radiated angular momentum [A. Geralico, arXiv:2507.03442 [gr-qc]]) with state-of-the-art post-Minkowskian scattering results [M.~Driesse et al., Nature \textbf{641}, no.8063, 603-607 (2025)].

Esther Natalia Guardiola, S. Sumitro, Sri Widyarti

It is well known that bitter gourd and noni fruit contain high levels of beneficial chemicals, but tastes and flavour are less appealing. Due to enzymatic transformation, fermentation can change bioactive compounds that minimize bad taste and unpleasant odor. This study aimed to assess the phenol and flavonoid content and antioxidant activity of bitter gourd (Momordica charantia L.) and noni fruit (Morinda citrifolia) during fermentation in honey. Blendered-bitter gourd (BG) or noni fruit (NF) each is mixed with honey and distilled water in a ratio of 3:1:10, then fermented for 90 days at room temperature and anaerobic conditions. Total phenol (TPC), total flavonoid content (TFC), and antioxidant activity were measured every two weeks. TPC in fermented NF increased from 56.62 mg GAE/gr to 156.59 GAE in the 6-week. TPC in BG increased from 56.96 GAE/g to 146.39 GAE/g during 12-week fermentation. TFC of fermented NF increased from 4.55 mg QC/g to 12.92 mg QC/g in 12-week fermentation. TFC of fermented BG increased from 9.86 QC/g to 41.69 QC/g in 12 weeks of fermentation. The antioxidant activity of fermented BM and BP showed the highest antioxidant activity in the 6-week (0,574 mg TEAC/g and 0.528 mg TEAC/g). The results indicate that fermentation in honey can increase total phenol and flavonoid content, and the antioxidant activity of bitter gourd and noni fruit.

Yuska Ainal Akbar, Gladys Trista Lituhayu, Ananda Ariski Putri et al.

Penelitian ini bertujuan untuk menganalisis karakteristik tanah dan menentukan jenis pondasi yang digunakan. Data primer terdiri dari data sondir dan hand boring. Data Sondir diambil pada dua titik yang berbeda. Hand boring dilakukan pada kedalaman 0,5 m dan 1 m. Pengujian tanah terdiri dari sondir, hand boring, Atterberg Limit, analisis butiran tanah, berat isi tanah dan kadar air. Analisis karakteristik tanah terdiri dari jenis tanah, Liquid Limit (LL), Plasticity Indeks (PI) dan kedalaman tanah keras.  Hasil pengujian sondir menunjukkan bahwa pada titik 1 (S1) kedalaman tanah keras 5,80 m dan titik 2 (S2) kedalaman tanah keras 6,00 m dengan nilai perlawanan konus (qc) sebesar 440 kg/cm² dan 390 kg/cm². Hasil pengujian hand boring menunjukkan bahwa jenis tanah termasuk kategori tanah berbutir kasar. Analisis butiran tanah menunjukkan bahwa persentase tanah yang tertahan ayakan No. 200 pada kedalaman 0,5 m dan 1 m sebesar 99,24% dan 99,16%. Berat isi sebesar 2,11 gr/cm³ (0,5 m) dan 2,23 gr/cm³ (1 m), sedangkan nilai kadar air pada kedalaman 0,5 m dan 1,0 m sebesar 22,84% dan 20,21%. Berdasarkan karakteristik tanah tersebut, maka jenis pondasi yang digunakan pada perencanaan Gedung Auditorium UBB adalah jenis pondasi dalam (pondasi strauss pile atau bor pile manual).

R. A. Sussman, C. Mantica, L. Molinari et al.

We address in this article the criticism in a recently submitted article by Clement and Noiucer (arXiv:2312.17662 [gr-qc]) on"Cotton Gravity"(CG), a gravity theory alternative to General Relativity. These authors claim that CG is"not predictive"for producing"too many"spherically symmetric vacuum solutions, while taking the Bianchi I vacuum as test case they argue that geometric constraint on the Cotton tensor lead to an undetermined problem, concluding in the end that CG"is not a physical theory". We provide arguments showing that this critique is incorrect and misrepresents the theory.

R. A. Sussman, C. Mantica, L. Molinari et al.

Clement and Noiucer submitted a note {\tt arXiv:2401.16008 [gr-qc]} replying to our criticism {\tt arXiv:2401.10479 [gr-qc]} of their previous submission. We reply to the contents of this note and remark that these authors have not addressed our arguments. This will be our last response to them. Readers are advised to look at all material and judge by themselves

M. F. Fauzi, H. S. Ramadhan, A. Sulaksono

A connection between regular black holes and horizonless ultracompact objects was proposed in Carballo-Rubio et al. (JHEP 08:046, 2023, arXiv:2211.05817 [gr-qc]). In this paper, we construct a model of a horizonless compact object, specifically an anisotropic gravastar with continuous pressure, that corresponds to regular black hole spacetime in the appropriate limit. The construction begins by modeling an equation of state that satisfies the anisotropic gravastar conditions and transitions to the de Sitter (p=-ϵ\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$p=-\epsilon $$\end{document}) upon horizon formation. The spacetime structure is similar to the Quantum Horizonless Compact Object (QHCO) described in Chen and Yokokura (Phys Rev D 109:104058, 2024, arXiv:2403.09388 [gr-qc]). Within this model, we also generate images of the corresponding objects surrounded by a thin accretion disk. The resulting images reveal that assuming that the emitting matter exists only outside the object, the inner light ring structure closely resembles that of the horizonless configuration of a regular black hole and the QHCO, yet it exhibits a distinct light ring structure compared to the thin-shell gravastar model. However, the opposite occurs when emitting matter is taken into account inside the object.

Ali Derekeh, Behrouz Mirza, P. Heidari et al.

We derive a class of Taub-NUT metrics in the presence of a scalar field (TNS) by using Ernst equations and potential, as well as using Ehlers transformations on the exact solutions that was recently introduced in Azizallahi et al. (Nucl Phys B 998:116414, https://doi.org/10.1016/j.nuclphysb.2023.116414, arXiv:2307.09328 [gr-qc], 2023) and Mirza et al. (Eur Phys J C 83:1161, https://doi.org/10.1140/epjc/s10052-023-12255-7, arXiv:2307.13588 [gr-qc], 2023). Furthermore, we investigate the effective potential, geodesics, topological charge, quasinormal modes (QNMs) and the deflection angle of light in a gravitational lensing for the obtained class of TNS metrics. We also use conformal transformations to generate a new class of exact solutions of the Einstein-conformal-scalar theory by using the obtained TNS solutions as seed metrics. Finally we compare QNMs of the class of exact solutions.

Yvonne Stahl, René H. Wink, G. Ingram et al.