İstanbul Bilgi Üniversitesi Kurumsal Akademik Arşivi
Güncel Gönderiler
Diffeomorphism invariance breaking in gravity and cosmological evolution
(Springer, 2025) Aydemir, Ufuk; Elbistan, Mahmut
Diffeomorphism invariance breaking has been investigated in the literature in several contexts, including emergent General Relativity (GR). If GR emerges from an underlying theory without diffeomorphism invariance, there may be small violations of this symmetry at low energies. Since such small violations should not cause instabilities in cosmological evolution, it is a suitable framework for examining such symmetry-breaking effects. In this paper, the cosmological evolution with broken diffeomorphism invariance is investigated in the (modified) FLRW spacetime in the effective theory framework. The GR Lagrangian is augmented with all diffeomorphism-breaking but Lorentz-invariant terms in the leading order, namely, those involving two derivatives. The magnitudes of (minor) violations are kept general modulo the conditions arising in the linearized theory. The analytic solutions of the scale factor in the full non-linear theory for the single-component universes are attempted; the radiation and vacuum solutions are found analytically, whereas the matter solution is worked out numerically since an analytic solution does not exist in the required form. It is observed that the solutions smoothly connect to those of GR in the limit of vanishing symmetry-breaking. The more realistic, two-component, and three-component universes are numerically studied, and no signs of singular behavior are observed: minor diffeomorphism-violating modifications to GR at the level of two derivatives do not cause instabilities in the basic cosmological evolution.
Trajectory Generation and Control for UAVs Using Quintic PH Curves and Kolmogorov-Arnold Networks (KANs)
(Ieee, 2025) Ciftci, Fatma Senguler; Oniz, Yesim
This paper presents a novel methodology that utilizes quintic Pythagorean-Hodograph (PH) curves for trajectory generation of unmanned aerial vehicles (UAVs) and Kolmogorov-Arnold Networks (KANs) for tracking problem. PH curves enable exact arc length computation and ensures smooth transitions in positions, velocities, and accelerations throughout the trajectory. The UAV's movements along the generated trajectory are regulated by KAN-based controllers. A separate controller is designed for each axis. We validate through simulations, indicating that a 40% improvement in tracking accuracy can be attained with KANs over conventional multilayer perceptrons (MLPs) under wind disturbances.
Karachay-Balkar converb clauses
(Harrassowitz Verlag, 2024) Gurer, Asli
This study investigates the internal and external syntax of {-(I)b) converb clauses in the Karachay-Balkar variety spoken in Konya, Turkey. It proposes that (i) converb clauses with {-(1)b) do not form a homogeneous group, (ii) the different and same-subject {-(I)b) con- verbs are not reduced and can include CP-level projections, (iii) the external syntax of the converbs differs, and converbs can attach at the CP, TP, or VP level, (iv) verb forms in {-(I)b), as predicates in finite clauses, express postterminality, and resultatives.
Sincerity and the Ideal of the Authentic Self: Melville's Bartleby
(Johns Hopkins Univ Press, 2025) Turner, Zeynep Talay
The figure of Bartleby has puzzled many thinkers. Interpretations vary, but the common point in many accounts is that Bartleby is beyond any conceptualization. In this paper I will ask whether he can nevertheless be understood in terms of the problem of authenticity. I will initially follow Lionel Trilling's famous argument, that is, the ethical ideal of the authentic self had replaced an earlier one he called sincerity, and that Bartleby, being an authentic figure, can be treated as an illustration of this. Then, I will take the discussion further by examining Bartleby via Giorgio Agamben's account of ethics.
Cognitive Difficulties, Coping Strategies and Barriers to Participation in Cognitive Rehabilitation in People with Multiple Sclerosis: A Qualitative Study Across Different Disability Levels
(Sage Publications Ltd, 2025) Karakas, Hilal; Yavas, Ipek; Gokcen, Rabia; Celik, Gozubatik; Cansiz, Melek; Ertekin, Ozge; Kahraman, Turhan
[Abstract Not Available]
