Mapúa University

Rituals in medical practice have either been seen as an anthropological aspect of current biomedical processes or as a pre-scientific aspect of complementary and alternative medicine (CAM). In either tendency, the literature has since failed to account for these rituals as rituals—conveyors of meaning, expressions of identity, and even as a rite of passage from illness to wellness. As an alternative to current discussions, this paper presents the case study of tawas, a diagnostic ritual from Philippine traditional medicine that determines personalistic and mystical causes of illnesses. As a non-intrusive procedure, tawas involves incantations and some ritual objects, e.g., rice, candle, axe, etc., that do not pose any direct harm nor benefit to the patient. While complete reliance on tawas at the expense of proper medical procedures could harm patients, the very ritual of tawas itself occupies a limbo within non-beneficence and non-maleficence. Following a Wittgensteinian perspective of treating rituals as meaning-laden human activities, this paper argues that rituals like tawas, much like other rituals embedded in biomedical practices, should be understood as rituals and not as empirical cures, thereby allowing their tolerance in medical practice in general.

This study probes spacetime solutions within Einstein-Bumblebee gravity, a modified gravitational framework incorporating spontaneous Lorentz symmetry violation through a vector field mechanism. By introducing a cosmological constant into this model, the research scrutinizes thermodynamic properties of black holes in both anti-de Sitter (AdS) and de Sitter (dS) geometries. The investigation demonstrates how Lorentz-violating parameters alter foundational thermodynamic principles, including revisions to the first law of black hole mechanics and shifts in critical phenomena during phase transitions. Notably, the bumblebee coupling parameter emerges as a critical factor governing horizon structure and thermal emission characteristics, with pronounced deviations from general relativity (GR) predictions observed as this parameter increases. The analysis extends to observational signatures by calculating shadow profiles of these modified black holes. Shadow morphology exhibits dual dependence on the cosmological constant and the bumblebee parameter, presenting measurable discrepancies from classical relativity that could be constrained through Event Horizon Telescope (EHT) observational data. Furthermore, using geometric formalisms, the study quantifies light deflection phenomena in weak and strong gravitational regimes. Results reveal that both the cosmological constant and Lorentz-violating parameter induce detectable modifications to lensing angles compared to Schwarzschild or Kerr benchmarks. These deviations, while subtle, underscore the necessity for next-generation astronomical instruments capable of resolving fine-scale spacetime curvature effects.

Motivated by the work of Scully et al. [ Proc. Nat. Acad. Sci. 115, 8131 (2018)] and Camblong et al.[ Phys. Rev. D 102, 085010 (2020)], we investigate horizon-brightened acceleration radiation (HBAR) for freely falling two-level atoms in the geometry of a Bardeen regular black hole. Building on the quantum-optics approach to acceleration radiation and its near-horizon conformal quantum mechanics (CQM) structure, we show that the dominant physics is again governed by an inverse-square potential in the radial Klein-Gordon equation, with an effective coupling fixed by the Bardeen surface gravity. Using geodesic expansions and a near-horizon CQM reduction of the scalar field, we derive the excitation probability for atoms falling through a Boulware-like vacuum in the presence of a stretched-horizon mirror. The resulting spectrum is Planckian in the mode frequency, with a temperature determined by the Bardeen Hawking temperature. We analyze how the regular core parameter controls the strength of the radiation and demonstrate that the excitation probability is strongly suppressed as the geometry approaches the extremal (cold remnant) limit. Numerical results illustrate the dependence of the spectrum on the Bardeen parameter and on the atomic transition frequency.

We study the motion of spinning test particles in Schwarzschild spacetime within the Mathisson–Papapetrou–Dixon pole–dipole approximation, imposing the Tulczyjew–Dixon spin supplementary condition. Restricting to equatorial orbits with the particle spin aligned with the orbital angular momentum, and retaining terms through linear order in the specific spin s, we derive the spin-corrected radial potential, circular-orbit conditions, bound periodic trajectories, epicyclic frequencies, and Lyapunov exponents of unstable circular orbits. The spin–curvature coupling shifts the circular-orbit energy and angular momentum and moves the innermost stable circular orbit to r_ ISCO=6M-2√(2/3) s+𝒪(s^2) in the sign convention adopted here. We construct bound periodic orbits using the Levin–Perez-Giz zoom–whirl taxonomy and show how the particle spin deforms the corresponding energy–angular-momentum map. We then obtain the coordinate-time azimuthal and radial epicyclic frequencies and use them as kinematical inputs for relativistic-precession and resonance prescriptions for quasi-periodic oscillations. Finally, we relate the Lyapunov exponent of unstable circular orbits to the local separatrix structure governing near-homoclinic zoom–whirl motion. The resulting formulation provides a compact analytic connection between linear-in-spin MPD dynamics, periodic-orbit taxonomy, epicyclic-frequency shifts, and transient strong-field phenomenology in a nonrotating black-hole background. Also, we study the gravitational waveforms from the periodic orbits of a massive spinning particle around a black hole, presenting those associated with extreme mass-ratio inspirals involving a stellar-mass compact spinning object orbiting a supermassive black hole.