cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Iterative weak approximation and hard bounds for switching diffusion
Creators: name: Qiu, Qinjing
name: Kawai, Reiichiro
Publisher: name: arXiv
Year: 2022
Subjects: subject: Numerical Analysis (math.NA)
subject: Probability (math.PR)
subject: FOS: Mathematics
subject: 60J27, 60H10, 60J22, 65C30

description: We establish a novel convergent iteration framework for a weak approximation of general switching diffusion. The key theoretical basis of the proposed approach is a restriction of the maximum number of switching so as to untangle and compensate a challenging system of weakly coupled partial differential equations to a collection of independent partial differential equations, for which a variety of accurate and efficient numerical methods are available. Upper and lower bounding functions for the solutions are constructed using the iterative approximate solutions. We provide a rigorous convergence analysis for the iterative approximate solutions, as well as for the upper and lower bounding functions. Numerical results are provided to examine our theoretical findings and the effectiveness of the proposed framework.
description: 19 pages, 4 figures
Regularity and Continuity properties of the sub-Riemannian exponential map
Creators: name: Borza, Samuël
name: Klingenberg, Wilhelm
Publisher: name: arXiv
Year: 2021
Subjects: subject: Differential Geometry (math.DG)
subject: FOS: Mathematics
subject: 53C17, 53B15, 53B99, 49J15

description: We prove a version of Warner's regularity and continuity properties for the sub-Riemannian exponential map. The regularity property is established by considering sub-Riemannian Jacobi fields while the continuity property follows from studying the Maslov index of Jacobi curves. We finally show how this implies that the exponential map of the three dimensional Heisenberg group is not injective in any neighbourhood of a conjugate vector.
description: 23 pages, 1 figure. v2: 23 pages, significant improvements; published in The Journal of Dynamical and Control Systems
Estimating earthquake-induced tsunami height probabilities without sampling
Creators: name: Tong, Shanyin
name: Vanden-Eijnden, Eric
name: Stadler, Georg
Publisher: name: arXiv
Year: 2021
Subjects: subject: Geophysics (physics.geo-ph)
subject: Numerical Analysis (math.NA)
subject: Optimization and Control (math.OC)
subject: FOS: Physical sciences
subject: FOS: Mathematics

description: Given a distribution of earthquake-induced seafloor elevations, we present a method to compute the probability of the resulting tsunamis reaching a certain size on shore. Instead of sampling, the proposed method relies on optimization to compute the most likely fault slips that result in a seafloor deformation inducing a large tsunami wave. We model tsunamis induced by bathymetry change using the shallow water equations on an idealized slice through the sea. The earthquake slip model is based on a sum of multivariate log-normal distributions, and follows the Gutenberg-Richter law for moment magnitudes 7--9. For a model problem inspired by the Tohoku-Oki 2011 earthquake and tsunami, we quantify annual probabilities of differently sized tsunami waves. Our method also identifies the most effective tsunami mechanisms. These mechanisms have smoothly varying fault slip patches that lead to an expansive but moderately large bathymetry change. The resulting tsunami waves are compressed as they approach shore and reach close-to-vertical leading wave edge close to shore.
Time-resolved chiral X-Ray photoelectron spectroscopy with transiently enhanced atomic site-selectivity: a Free Electron Laser investigation of electronically excited fenchone enantiomers
Creators: name: Faccialà, D.
name: Devetta, M.
name: Beauvarlet, S.
name: Besley, N.
name: Calegari, F.
name: Callegari, C.
name: Catone, D.
name: Cinquanta, E.
name: Ciriolo, A. G.
name: Colaizzi, L.
name: Coreno, M.
name: Crippa, G.
name: De Ninno, G.
name: Di Fraia, M.
name: Galli, M.
name: Garcia, G. A.
name: Mairesse, Y.
name: Negro, M.
name: Plekan, O.
name: Geetha, P. Prasannan
name: Prince, K. C.
name: Pusala, A.
name: Stagira, S.
name: Turchini, S.
name: Ueda, K.
name: You, D.
name: Zema, N.
name: Blanchet, V.
name: Nahon, L.
name: Powis, I.
name: Vozzi, C.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Chemical Physics (physics.chem-ph)
subject: FOS: Physical sciences

description: Chiral molecules are widespread in nature, playing a fundamental role in bio-chemical processes and in the origin of life itself. The observation of dynamics in chiral molecules is crucial for the understanding and control of the chiral activity of photo-excited states. One of the most promising techniques for the study of photo-excited chiral systems is time-resolved photoelectron circular dichroism (TR-PECD), which offers an intense and sensitive probe for vibronic and geometric molecular structure as well as electronic structures, and their evolution on a femtosecond timescale. However, the non-local character of the PECD effect, which is imprinted during the electron scattering off the molecule, makes the interpretation of TR-PECD experiments challenging. In this respect, core-photoionization is known to allow site- and chemical-sensitivity to photelectron spectroscopy. Here we demonstrate that TR-PECD utilising core-level photoemission enables probing the chiral electronic structure and its relaxation dynamics with atomic site sensitivity. Following UV pumped excitation to a 3s Rydberg state, fenchone enantiomers (C 10 H 16 O) were probed on a femtosecond scale using circularly polarized soft X-ray light pulses provided by the free-electron laser FERMI. C 1s binding energy shifts caused by the redistribution of valence electron density in this 3s-valence-Rydberg excitation allowed us to measure transient PECD chiral responses with an enhanced C-atom site-selectivity compared to that achievable in the ground state molecule. These results represent the first chemical-specific and site-specific, enantio-sensitive observations on the electronic structure of a photo-excited chiral molecule and pave the way towards chiral femtochemistry probed by core-level photoemission.
Electric Field Screening with Back-Flow at Pulsar Polar Cap
Creators: name: Kisaka, Shota
name: Asano, Katsuaki
name: Terasawa, Toshio
Publisher: name: arXiv
Year: 2016
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: Recent $γ$-ray observations suggest that the particle acceleration occurs at the outer region of the pulsar magnetosphere. The magnetic field lines in the outer acceleration region (OAR) are connected to the neutron star surface (NSS). If copious electron--positron pairs are produced near the NSS, such pairs flow into the OAR and screen the electric field there. To activate the OAR, the electromagnetic cascade due to the electric field near the NSS should be suppressed. However, since a return current is expected along the field lines through the OAR, the outflow extracted from the NSS alone cannot screen the electric field just above the NSS. In this paper, we analytically and numerically study the electric-field screening at the NSS taking into account the effects of the back-flowing particles from the OAR. In certain limited cases, the electric field is screened without significant pair cascade if only ultrarelativistic particles ($γ\gg1$) flow back to the NSS. On the other hand, if electron--positron pairs with a significant number density and mildly relativistic temperature, expected to distribute in a wide region of the magnetosphere, flow back to the NSS, these particles adjust the current and charge densities, so that the electric field can be screened without pair cascade. We obtain the condition for the number density of particles to screen the electric field at the NSS. We also find that in ion-extracted case from the NSS, bunches of particles are ejected to the outer region quasi-periodically, which is a possible mechanism of observed radio emission.
description: 15 pages, 13 figures, 1 table. Accepted for publication in Astrophysical Journal
Report on stakeholder meeting describing the model for a 21st century pregnancy data collection and signal detection system which should be able to replace traditional pregnancy registries (D2.1)
Creators: name: Yates, Laura
name: Lewis, David
name: Alexe, Amalia
name: Oliver, Alison
Publisher: name: Zenodo
Year: 2023

description: This report summarises the key aspects and findings of the “Moving pregnancy pharmacovigilance into the 21st century” cross-stakeholder workshop, delivered on 25th January 2022 by IMI ConcePTION WP2, under task 2.1.
GENOME: A GENeric methodology for Ontological Modelling of Epics
Creators: name: Varadarajan, Udaya
name: Bagchi, Mayukh
name: Tiwari, Amit
name: Satija, M. P.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Digital Libraries (cs.DL)
subject: Artificial Intelligence (cs.AI)
subject: FOS: Computer and information sciences

description: Ontological knowledge modelling of epics, though being an established research arena backed by concrete multilingual and multicultural works, still suffer from two key shortcomings. Firstly, all epic ontological models developed till date have been designed following ad-hoc methodologies, most often, combining existing general purpose ontology development methodologies. Secondly, none of the ad-hoc methodologies consider the potential reuse of existing epic ontological models for enrichment, if available. The paper presents, as a unified solution to the above shortcomings, the design and development of GENOME - the first dedicated methodology for iterative ontological modelling of epics, potentially extensible to works in different research arenas of digital humanities in general. GENOME is grounded in transdisciplinary foundations of canonical norms for epics, knowledge modelling best practices, application satisfiability norms and cognitive generative questions. It is also the first methodology (in epic modelling but also in general) to be flexible enough to integrate, in practice, the options of knowledge modelling via reuse or from scratch. The feasibility of GENOME is validated via a first brief implementation of ontological modelling of the Indian epic - Mahabharata by reusing an existing ontology. The preliminary results are promising, with the GENOME-produced model being both ontologically thorough and performance-wise competent
Constraining in-medium heavy-quark energy-loss mechanisms via angular correlations between heavy and light mesons
Creators: name: Rohrmoser, Martin
name: Gossiaux, Pol Bernard
name: Gousset, Thierry
name: Aichelin, Jörg
Publisher: name: arXiv
Year: 2016
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: Two-particle correlations obtained from parton showers that pass the hot and dense medium of the quark gluon plasma (QGP) can be used as an alternative observable, in addition to the combination of the nuclear modification factor $R_{AA}$ and the elliptic flow $v_2$, to study the mechanisms of in-medium heavy quark energy-loss. In particular, angular correlations represent a promising tool to distinguish between energy loss due to collisional and radiative interactions of jet and medium particles. To this end, parton cascades were created in Monte-Carlo simulations, where individual particles can undergo both parton splitting as well as an effective jet-medium interaction. A first model simulates the effects of induced radiations on parton cascades. Its consequences on angular correlations of partons within jets were studied in detail, with particular focus on angular broadening. The results can be compared to a second model that effectively describes elastic scatterings of jet and medium particles.
An investigation into psychosocial factors influencing mental health and well-being in Indonesia
Creators: name: Kilis, Grace
Publisher: name: CQUniversity
Year: 2023
Subjects: Health psychology
Psychology of religion
Clinical psychology

description: This study explores the nature and conceptualisation of mental health and well-being among Indonesians living in an urban environment. Little is known about the nature of mental health and well-being in the everyday living context in developing countries. In Indonesia, as one of the most populous countries and the largest Muslim population in the world, the incidence of mental health problems has increased immensely in the last decade. However, there is a very limited number of studies that incorporate relevant cultural contexts into the understanding of mental health and well-being in Indonesia. This study aims to elucidate the relationship of specific psychosocial factors, as protective and risk factors, to mental health and well-being in the everyday urban living contexts experienced by a growing middle class in Indonesia in the perspective of Keyes' model of mental well-being. The data for this study were collected through semi-structured interviews and were analysed using Giorgi’s descriptive phenomenological approach.
SGM3D: Stereo Guided Monocular 3D Object Detection
Creators: name: Zhou, Zheyuan
name: Du, Liang
name: Ye, Xiaoqing
name: Zou, Zhikang
name: Tan, Xiao
name: Zhang, Li
name: Xue, Xiangyang
name: Feng, Jianfeng
Publisher: name: arXiv
Year: 2021
Subjects: subject: Computer Vision and Pattern Recognition (cs.CV)
subject: FOS: Computer and information sciences

description: Monocular 3D object detection aims to predict the object location, dimension and orientation in 3D space alongside the object category given only a monocular image. It poses a great challenge due to its ill-posed property which is critically lack of depth information in the 2D image plane. While there exist approaches leveraging off-the-shelve depth estimation or relying on LiDAR sensors to mitigate this problem, the dependence on the additional depth model or expensive equipment severely limits their scalability to generic 3D perception. In this paper, we propose a stereo-guided monocular 3D object detection framework, dubbed SGM3D, adapting the robust 3D features learned from stereo inputs to enhance the feature for monocular detection. We innovatively present a multi-granularity domain adaptation (MG-DA) mechanism to exploit the network's ability to generate stereo-mimicking features given only on monocular cues. Coarse BEV feature-level, as well as the fine anchor-level domain adaptation, are both leveraged for guidance in the monocular domain.In addition, we introduce an IoU matching-based alignment (IoU-MA) method for object-level domain adaptation between the stereo and monocular predictions to alleviate the mismatches while adopting the MG-DA. Extensive experiments demonstrate state-of-the-art results on KITTI and Lyft datasets.
description: 8 pages, 5 figures
A Statistical Framework to Investigate the Optimality of Signal-Reconstruction Methods
Creators: name: Bohra, Pakshal
name: Pla, Pol del Aguila
name: Giovannelli, Jean-François
name: Unser, Michael
Publisher: name: arXiv
Year: 2022
Subjects: subject: Signal Processing (eess.SP)
subject: FOS: Electrical engineering, electronic engineering, information engineering

description: We present a statistical framework to benchmark the performance of reconstruction algorithms for linear inverse problems, in particular, neural-network-based methods that require large quantities of training data. We generate synthetic signals as realizations of sparse stochastic processes, which makes them ideally matched to variational sparsity-promoting techniques. We derive Gibbs sampling schemes to compute the minimum mean-square error estimators for processes with Laplace, Student's t, and Bernoulli-Laplace innovations. These allow our framework to provide quantitative measures of the degree of optimality (in the mean-square-error sense) for any given reconstruction method. We showcase our framework by benchmarking the performance of some well-known variational methods and convolutional neural network architectures that perform direct nonlinear reconstructions in the context of deconvolution and Fourier sampling. Our experimental results support the understanding that, while these neural networks outperform the variational methods and achieve near-optimal results in many settings, their performance deteriorates severely for signals associated with heavy-tailed distributions.
K-stability of Gorenstein Fano group compactifications with rank two
Creators: name: Lee, Jae-Hyouk
name: Park, Kyeong-Dong
name: Yoo, Sungmin
Publisher: name: arXiv
Year: 2022
Subjects: subject: Differential Geometry (math.DG)
subject: Algebraic Geometry (math.AG)
subject: Complex Variables (math.CV)
subject: FOS: Mathematics
subject: Primary: 14M27, 32Q20, Secondary: 32M12, 53C55

description: We give a classification of Gorenstein Fano bi-equivariant compactifications of semisimple complex Lie groups with rank two, and determine which of them are equivariant K-stable and admit (singular) Kähler-Einstein metrics. As a consequence, we obtain several explicit examples of K-stable Fano varieties admitting (singular) Kähler-Einstein metrics. We also compute the greatest Ricci lower bounds, equivalently the delta invariants for K-unstable varieties. This gives us three new examples on which each solution of the Kähler-Ricci flow is of type II.
description: 33 pages, 8 figures
Experimental demonstration of robustness under scaling errors for superadiabatic population transfer in a superconducting circuit
Creators: name: Dogra, Shruti
name: Vepsäläinen, Antti
name: Paraoanu, Gheorghe Sorin
Publisher: name: arXiv
Year: 2022
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We study experimentally and theoretically the transfer of population between the ground state and the second excited state in a transmon circuit by the use of superadiabatic stimulated Raman adiabatic passage (saSTIRAP). We show that the transfer is remarkably resilient against variations in the amplitudes of the pulses (scaling errors), thus demostrating that the superadiabatic process inherits certain robustness features from the adiabatic one. In particular, we put in evidence a new plateau that appears at high values of the counterdiabatic pulse strength, which goes beyond the usual framework of saSTIRAP.
description: 9 figures
Constraining the Gravitational-Wave Spectrum from Cosmological First-Order Phase Transitions Using Data from LIGO-Virgo First Three Observing Runs
Creators: name: Jiang, Yang
name: Huang, Qing-Guo
Publisher: name: arXiv
Year: 2022
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We search for a first-order phase transition (PT) gravitational wave (GW) signal from Advanced LIGO and Advanced Virgo's first three observing runs. Due to the large theoretical uncertainties, four GW energy spectral shapes from bubble and sound wave collisions widely adopted in literature are investigated, separately. Our results indicate that there is no evidence for the existence of such GW signals, and therefore we give the upper limits on the amplitude of GW energy spectrum $Ω_\text{pt}(f_*)$ in the peak frequency range of $f_*\in [5,500]$ Hz for these four theoretical models, separately. We find that $Ω_\text{pt}(f_*\simeq 40\ \text{Hz})<1.3\times10^{-8}$ at $95\%$ credible level, and roughly $H_*/β\lesssim 0.1$ and $α\lesssim 1$ at $68\%$ credible level in the peak frequency range of $20\lesssim f_*\lesssim 100$ Hz corresponding to the most sensitive frequency band of Advanced LIGO and Advanced Virgo's first three observing runs, where $H_*$ is the Hubble parameter when PT happens, $β$ is the bubble nucleation rate and $α$ is the ratio of vacuum and relativistic energy density.
description: 7 pages, 3 figures, 3 tables; minor revision, some errors corrected
Resonance-enhanced collective effect in a triangle arrangement of Rydberg atoms with anisotropic interactions
Creators: name: Qian, Jing
Publisher: name: arXiv
Year: 2016
Subjects: subject: Atomic Physics (physics.atom-ph)
subject: Quantum Gases (cond-mat.quant-gas)
subject: FOS: Physical sciences

description: We investigate the collective excitation effect in a scheme where three identical Rydberg atoms are arranged in an equilateral triangular lattice. By using a static electric field polarizing the atomic dipoles, the dipole-dipole interactions between two Rydberg atoms are essentially anisotropic and can even disappear in the several special resonance cases. For that fact, we observe collectively enhanced excitation probability of single Rydberg atom in resonant areas in the case of strong blockade, and that of double or triple Rydberg atoms in the case of partial blockade. To give more evidences for this collective excitation enhancement, we study the two-body quantum correlation between three Rydberg atoms, as well as the dependence of the blockade radius on the length of triangle sides, which present a good agreement with the excitation properties.
description: accepted by josab
Disturbance Observer-based Robust Control Barrier Functions
Creators: name: Wang, Yujie
name: Xu, Xiangru
Publisher: name: arXiv
Year: 2022
Subjects: subject: Systems and Control (eess.SY)
subject: Optimization and Control (math.OC)
subject: FOS: Electrical engineering, electronic engineering, information engineering
subject: FOS: Mathematics

description: This work presents a safe control design approach that integrates the disturbance observer (DOB) and the control barrier function (CBF) for systems with external disturbances. Different from existing robust CBF results that consider the "worst case" of disturbances, this work utilizes a DOB to estimate and compensate for the disturbances. DOB-CBF-based controllers are constructed with provably safe guarantees by solving convex quadratic programs online, to achieve a better tradeoff between safety and performance. Two types of systems are considered individually depending on the magnitude of the input and disturbance relative degrees. The effectiveness of the proposed methods is illustrated via numerical simulations.
description: Accepted to American Control Conference (ACC) 2023
Hollenbeck-Verbitsky conjecture on best constant inequalities for analytic and co-analytic projections
Creators: name: Melentijević, Petar
Publisher: name: arXiv
Year: 2022
Subjects: subject: Complex Variables (math.CV)
subject: Functional Analysis (math.FA)
subject: FOS: Mathematics
subject: 35B30, 35J05

description: \begin{abstract} In this paper we address the problem of finding the best constants in inequalities of the form: $$ \|\big(|P_+f|^s+|P_-f|^s\big)^{\frac{1}{s}}\|_{L^p({\mathbb{T}})}\leq A_{p,s} \|f\|_{L^p({\mathbb{T}})},$$ where $P_+f$ and $P_-f$ denote analytic and co-analytic projection of a complex-valued function $f \in L^p({\mathbb{T}}),$ for $p \geq 2$ and all $s>0$, thus proving Hollenbeck-Verbitsky conjecture from \cite{HV.OTAA}. We also prove the same inequalities for\\ $1
description: 34 pages; this version is accepted for publication in Mathematische Annalen
Atomistic Global Optimization X: A Python package for optimization of atomistic structures
Creators: name: Christiansen, Mads-Peter Verner
name: Rønne, Nikolaj
name: Hammer, Bjørk
Publisher: name: arXiv
Year: 2022
Subjects: subject: Chemical Physics (physics.chem-ph)
subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Modelling and understanding properties of materials from first principles require knowledge of the underlying atomistic structure. This entails knowing the individual identity and position of all involved atoms. Obtaining such information for macro-molecules, nano-particles, clusters, and for the surface, interface, and bulk phases of amorphous and solid materials represents a difficult high dimensional global optimization problem. The rise of machine learning techniques in materials science has, however, led to many compelling developments that may speed up such structure searches. The complexity of the new methods have established the necessity for an efficient way of experimenting with and assembling them into global optimization algorithms. In this paper we introduce the Atomistic Global Optimization X (AGOX) framework and code, as a customizable approach to building efficient global optimization algorithms. A modular way of expressing global optimization algorithms is described and modern programming practices are used to enable that modularity in the freely available AGOX python package. Two examples of global optimization problems are analyzed: One that is computationally inexpensive which is used to showcase that AGOX enables the expression of multiple global optimization algorithms. As the other example, AGOX is used for solving a complex atomistic optimization problem for a metal-nitride nano-cluster embedded in a graphene sheet as described at the density functional theory (DFT) level.
description: 18 pages, 19 figures
Understanding the role of anharmonic phonons in diffusion of bcc metal
Creators: name: Fattahpour, Seyyedfaridodin
name: Davariashtiyani, Ali
name: Kadkhodaei, Sara
Publisher: name: arXiv
Year: 2021
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Diffusion in high-temperature bcc phase of IIIB-IVB metals such as Zr, Ti, and their alloys is observed to be orders of magnitude higher than bcc metals of group VB-VIB, including Cr, Mo, and W. The underlying reason for this higher diffusion is still poorly understood. To explain this observation, we compare the first-principles-calculated parameters of monovancy-mediated diffusion between bcc Ti, Zr, and dilute Zr- Sn alloys and bcc Cr, Mo, and W. Our results indicate that strongly anharmonic vibrations promote both the vacancy concentration and the diffusive jump rate in bcc IVB metals and can explain their markedly faster diffusion compared to bcc VIB metals. Additionally, we provide an efficient approach to calculate diffusive jump rates according to the transition state theory (TST). The use of standard harmonic TST is impractical in bcc IIIB/IVB metals due to the existence of ill-defined harmonic phonons, and most studies use classical or ab initio molecular dynamics for direct simulation of diffusive jumps. Here, instead, we use a stochastically-sampled temperature-dependent phonon analysis within the transition state theory to study diffusive jumps without the need of direct molecular dynamics simulations. We validate our first-principles diffusion coefficient predictions with available experimental measurements and explain the underlying reasons for the promotion of diffusion in bcc IVB metals/alloys compared to bcc VIB metals.
description: 8 figures, 1 table, 5 supplementary figures, 1 supplementary table, 1 supplementary note
Perfect stimulated Raman adiabatic passage with imperfect finite-time pulses
Creators: name: Dogra, Shruti
name: Paraoanu, Gheorghe Sorin
Publisher: name: arXiv
Year: 2022
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We present a well-tailored sequence of two Gaussian-pulsed drives that achieves perfect population transfer in STImulated Raman Adiabatic Passage (STIRAP). We give a theoretical analysis of the optimal truncation and relative placement of the Stokes and pump pulses. Further, we obtain the power and the duration of the protocol for a given pulse width. Importantly, the duration of the protocol required to attain a desired value of fidelity depends only logarithmically on the infidelity. Subject to optimal truncation of the drives and with reference to the point of fastest transfer, we obtain a new adiabaticity criteria, which is remarkably simple and effective.
description: 7 pages, 7 figures
Global dynamics of the $2d$ NLS with white noise potential and generic polynomial nonlinearity
Creators: name: Tzvetkov, N.
name: Visciglia, N.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Probability (math.PR)
subject: Analysis of PDEs (math.AP)
subject: FOS: Mathematics

description: Using an approach introduced by Hairer-Labb\' e we construct a unique global dynamics for the NLS on $\T^2$ with a white noise potential and an arbitrary polynomial nonlinearity. We build the solutions as a limit of classical solutions (up to a phase shift) of the same equation with smoothed potentials. This is an improvement on previous contributions of us and Debussche-Weber dealing with quartic nonlinearities and cubic nonlinearities respectively.
The Nature of Low Surface Brightness Galaxies in the Hyper Suprime-Cam Survey
Creators: name: Greene, Jenny E
name: Greco, Johnny P.
name: Goulding, Andy D.
name: Huang, Song
name: Kado-Fong, Erin
name: Danieli, Shany
name: Li, Jiaxuan
name: Kim, Ji Hoon
name: Komiyama, Yutaka
name: Leauthaud, Alexie
name: MacArthur, Lauren A.
name: Sifon, Cristobal
Publisher: name: arXiv
Year: 2022
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We present the statistical redshift distribution of a large sample of low surface brightness (LSB) galaxies identified in the first 200 deg$^2$ of the Hyper Suprime-Cam Strategic Survey Program. Through cross-correlation with the NASA-SDSS Atlas, we find that the majority of objects lie within z<0.15 or ~ 500 Mpc, yielding a mass range of $M_*$ ~ $10^7-10^9$ M_sun and size range of $r_{\rm{eff,g}}$ ~ 1-8 kpc. We find a peak in the distance distribution within 100 Mpc, corresponding mostly to ~ $10^7$ M_sun galaxies that fall on the known mass-size relation. There is also a tail in the redshift distribution out to z~0.15, comprising more massive ($M_*=10^8-10^9$ M_sun) galaxies at the larger end of our size range. We see tentative evidence that at the higher-mass end ($M_* > 10^8$ M_sun) the LSB galaxies do not form a smooth extension of the mass-size relation of higher surface brightness galaxies, perhaps suggesting that the LSB galaxy population is distinct in its formation path.
description: 15 pages, 6 figures, resubmitted to ApJ after review
Generic Dijkstra: correctness and tractability
Creators: name: Szcześniak, Ireneusz
name: Woźna-Szcześniak, Bożena
Publisher: name: arXiv
Year: 2022
Subjects: subject: Networking and Internet Architecture (cs.NI)
subject: Data Structures and Algorithms (cs.DS)
subject: FOS: Computer and information sciences

description: The recently-proposed generic Dijkstra algorithm finds shortest paths in networks with continuous and contiguous resources. The algorithm was proposed in the context of optical networks, but is applicable to networks with finite and discrete resources. The algorithm was published without a proof of correctness, and with a minor shortcoming. We provide that missing proof and offer a correction to the shortcoming. To prove the algorithm correct, we generalize the Bellman's principle of optimality to algebraic structures with a partial ordering. We also argue the stated problem is tractable by analyzing the size of the search space in the worst-case.
Bridging disconnected networks of first and second lines of biologic therapies in rheumatoid arthritis with registry data: Bayesian evidence synthesis with target trial emulation
Creators: name: Bujkiewicz, Sylwia
name: Singh, Janharpreet
name: Wheaton, Lorna
name: Jenkins, David
name: Martina, Reynaldo
name: Hyrich, Kimme
name: Abrams, Keith R.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Applications (stat.AP)
subject: Methodology (stat.ME)
subject: FOS: Computer and information sciences

description: Objective: We aim to utilise real world data in evidence synthesis to optimise an evidence base for the effectiveness of biologic therapies in rheumatoid arthritis in order to allow for evidence on first-line therapies to inform second-line effectiveness estimates. Study design and setting: We use data from the British Society for Rheumatology Biologics Register for Rheumatoid Arthritis (BSRBR-RA) to supplement RCT evidence obtained from the literature, by emulating target trials of treatment sequences to estimate treatment effects in each line of therapy. Treatment effects estimates from the target trials inform a bivariate network meta-analysis (NMA) of first and second-line treatments. Results: Summary data were obtained from 21 trials of biologic therapies including 2 for second-line treatment and results from six emulated target trials of both treatment lines. Bivariate NMA resulted in a decrease in uncertainty around the effectiveness estimates of the second-line therapies, when compared to the results of univariate NMA, and allowed for predictions of treatment effects not evaluated in second-line RCTs. Conclusion: Bivariate NMA provides effectiveness estimates for all treatments in first- and second-line, including predicted effects in second-line where these estimates did not exist in the data. This novel methodology may have further applications, for example for bridging networks of trials in children and adults.
First results from the ENTOTO neutron monitor: Quantifying the waiting time distribution
Creators: name: Strauss, R. D.
name: Giday, Nigussie M.
name: Seba, Ephrem B.
name: Chekole, Daniel A.
name: Garuma, Gemechu F.
name: Kassa, Bereket H.
name: Dugassa, Teshome
name: Diedericks, C.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Instrumentation and Detectors (physics.ins-det)
subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: We discuss a newly established neutron monitor station installed at the ENTOTO Observatory Research Center outside of Addis Ababa, Ethiopia. This is a version of a mini-neutron monitor, recently upgraded to detect individual neutrons and able to calculate the waiting time distribution between neutron pulses down to $\sim 1 $ $μ$s. From the waiting time distribution we define and calculate a new quantity, the correlation ratio, as the ratio of correlated to uncorrelated neutrons measured inside the monitor. We propose that this quantity can, in future, be used as a proxy for spectral index of atmospheric particles incident on the monitor and show that this quantity has a weak pressure dependence. We believe that future measurements from the ENTOTO mini-neutron monitor will contribute towards the understanding of cosmic ray acceleration and transport in the heliosphere.
description: Submitted to Advances in Space Research spacial issue: Space and Geophysical Observations and Recent Results related to the African Continent
Correction to: Weak product spaces of Dirichlet series
Creators: name: Brevig, Ole Fredrik
name: Perfekt, Karl-Mikael
Publisher: name: arXiv
Year: 2022
Subjects: subject: Functional Analysis (math.FA)
subject: FOS: Mathematics

description: We correct the proof of Theorem~8 in [\emph{Weak product spaces of Dirichlet series}, Integral Equations Operator Theory \textbf{86} (2016), no.~4, 453--473.]
Implementing and characterizing precise multi-qubit measurements
Creators: name: Blumoff, J. Z.
name: Chou, K.
name: Shen, C.
name: Reagor, M.
name: Axline, C.
name: Brierley, R. T.
name: Silveri, M. P.
name: Wang, C.
name: Vlastakis, B.
name: Nigg, S. E.
name: Frunzio, L.
name: Devoret, M. H.
name: Jiang, L.
name: Girvin, S. M.
name: Schoelkopf, R. J.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: There are two general requirements to harness the computational power of quantum mechanics: the ability to manipulate the evolution of an isolated system and the ability to faithfully extract information from it. Quantum error correction and simulation often make a more exacting demand: the ability to perform non-destructive measurements of specific correlations within that system. We realize such measurements by employing a protocol adapted from [S. Nigg and S. M. Girvin, Phys. Rev. Lett. 110, 243604 (2013)], enabling real-time selection of arbitrary register-wide Pauli operators. Our implementation consists of a simple circuit quantum electrodynamics (cQED) module of four highly-coherent 3D transmon qubits, collectively coupled to a high-Q superconducting microwave cavity. As a demonstration, we enact all seven nontrivial subset-parity measurements on our three-qubit register. For each we fully characterize the realized measurement by analyzing the detector (observable operators) via quantum detector tomography and by analyzing the quantum back-action via conditioned process tomography. No single quantity completely encapsulates the performance of a measurement, and standard figures of merit have not yet emerged. Accordingly, we consider several new fidelity measures for both the detector and the complete measurement process. We measure all of these quantities and report high fidelities, indicating that we are measuring the desired quantities precisely and that the measurements are highly non-demolition. We further show that both results are improved significantly by an additional error-heralding measurement. The analyses presented here form a useful basis for the future characterization and validation of quantum measurements, anticipating the demands of emerging quantum technologies.
description: 10 pages, 5 figures, plus supplement
Design, architecture and safety evaluation of an AI chatbot for an educational approach to health promotion in chronic medical conditions
Creators: name: Kelly, Anthony
name: Noctor, Eoin
name: van de Ven, Pepijn
Publisher: name: University of Limerick
Year: 2025
Subjects: classificationCode: 4009
subject: Electronics, sensors and digital hardware

description: This paper presents the design, architecture, and safety evaluation of an AI chatbot tailored for educational purposes in man aging chronic medical conditions, focusing on Type 2 Diabetes Mellitus (T2DM). Leveraging conversational agents in health literacy, the chatbot integrates medically informed information, constrained responses, and response traceability to ensure appropriateness and compliance with protocols. By utilizing ChatGPT with retrieval augmented generation (RAG) and careful prompt engineering, the system ensures reliable, traceable, and privacy-conscious interactions. Safety and efficacy testing revealed just one inappropriate response (5%) in a simulated patient conversation and 15 (75%) fully appropriate responses. This study highlights the potential of AI chatbots in enhancing patient autonomy, reliability, and privacy in accessing medical knowledge for chronic conditions
The Mechanical Alignment of Dust (MAD) I: On the spin-up process of fractal grains by a gas-dust drift
Creators: name: Reissl, Stefan
name: Meehan, Paul
name: Klessen, Ralf S.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: FOS: Physical sciences

description: Context: Aligned dust grains are commonly exploited to probe the magnetic field orientation. However, the exact physical processes that result in a coherent large-scale grain alignment are far from being constrained. Aims: In this work, we aim to investigate the impact of a gas-dust drift leading to a mechanical alignment of dust (MAD) and to dust polarization. Methods: We explore fractal dust aggregates to statistically analyze the average alignment behavior of distinct grain ensembles. The spin-up efficiencies for individual aggregates are determined utilizing MC simulations. These efficiencies are analyzed to identify stable points for the grain alignment in direction of the gas-dust drift and along the magnetic field lines. Finally, the net dust polarization is calculated per grain ensemble. Results: The mechanical spin-up within the CNM is sufficient to drive grains to a stable alignment. A likely mechanical grain alignment is parallel to the drift direction. All grains can align at subsonic conditions. Here, we predict a polarization efficiency in the order of unity for the MAD. A supersonic drift may result in a rapid rotation where dust grains may become rotationally disrupted and the polarization becomes drastically reduced. In the presence of a magnetic field, the drift required for the alignment of elongated grains is roughly one order of magnitude higher compared to the pure MAD. Here, the dust polarization efficiency is 0.6-0.9 indicating that a drift can provide the prerequisites to probe the magnetic field. The alignment is inefficient when the direction of the drift and the field lines are perpendicular. Conclusions: We find that MAD has to be taken into consideration as an alternative driving mechanism where the standard RAT alignment theory fails to account for the full spectrum of available dust polarization observations.
description: 27 pages, 29 figures, 3 tables
The Infrared Imaging Spectrograph (IRIS) for TMT: the ADC optical design
Creators: name: Phillips, Andrew C.
name: Suzuki, Ryuji
name: Larkin, James E.
name: Moore, Anna M.
name: Hayano, Yutaka
name: Tsuzuki, Toshihiro
name: Wright, Shelley A.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: FOS: Physical sciences

description: We present the current optical design for the IRIS Atmospheric Dispersion Corrector (ADC). The ADC is designed for residual dispersions less than ~1 mas across a given passband at elevations of 25 degrees. Since the last report, the area of the IRIS Imager has increased by a factor of four, and the pupil size has increased from 75 to 90mm, both of which contribute to challenges with the design. Several considerations have led to the current design: residual dispersion, amount of introduced distortion, glass transmission, glass availability, and pupil displacement. In particular it was found that there are significant distortions that appear (two different components) that can lead to image blur over long exposures. Also, pupil displacement increases the wavefront error at the imager focus. We discuss these considerations, discuss the compromises, and present the final design choice and expected performance.
description: 9 pages, 7 figures, SPIE (2016) 9908-373
A computational approach to the twin paradox in curved spacetime
Creators: name: Fung, Kenneth K. H.
name: Clark, Hamish A.
name: Lewis, Geraint F.
name: Wu, Xiaofeng
Publisher: name: arXiv
Year: 2016
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: Despite being a major component in the teaching of special relativity, the twin `paradox' is generally not examined in courses on general relativity. Due to the complexity of analytical solutions to the problem, the paradox is often neglected entirely, and students are left with an incomplete understanding of the relativistic behaviour of time. This article outlines a project, undertaken by undergraduate physics students at the University of Sydney, in which a novel computational method was derived in order to predict the time experienced by a twin following a number of paths between two given spacetime coordinates. By utilising this method, it is possible to make clear to students that following a geodesic in curved spacetime does not always result in the greatest experienced proper time.
description: 14 pages, 5 figues, Accepted for publication in EJP
Faddeev-Jackiw quantization of four dimensional BF theory
Creators: name: Escalante, Alberto
name: Cavildo-Sánchez, Prihel
Publisher: name: arXiv
Year: 2016
Subjects: subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences

description: The symplectic analysis of a four dimensional $BF$ theory in the context of the Faddeev-Jackiw symplectic approach is performed. It is shown that this method is more economical than Dirac's formalism. In particular, the complete set of Faddeev-Jackiw constraints and the generalized Faddeev-Jackiw brackets are reported. In addition, we show that the generalized Faddeev-Jackiw brackets and the Dirac ones coincide to each other. Finally, the similarities and advantages between Faddeev-Jackiw method and Dirac's formalism are briefly discussed.
Short Electron Bunch Generation Using Single-Cycle Ultrafast Electron Guns
Creators: name: Fallahi, Arya
name: Fakhari, Moein
name: Yahaghi, Alireza
name: Arrieta, Miguel
name: Kärtner, Franz X.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Accelerator Physics (physics.acc-ph)
subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: We introduce a solution for producing ultrashort ($\sim$fs) high charge ($\sim$pC) from ultra-compact guns utilizing single-cycle THz pulses. We show that the readily available THz pulses with energies as low as 20 ?J are sufficient to generate multi-10 keV electron bunches. Moreover, It is demonstrated that THz energies of 2mJ are sufficient to generate relativistic electron bunches with higher than 2 MeV energy. The high acceleration gradients possible in the structures provide 30 fs electron bunches at 30 keV energy and 45 fs bunches at 2 MeV energy. These structures will underpin future devices for strong field THz physics in general and miniaturized electron guns, in which the high fields combined with the short pulse duration enable electron beams with ultrahigh brightness.
description: 13 pages, 6 figures
Weighing the Darkness II: Astrometric Measurement of Partial Orbits with Gaia
Creators: name: Andrews, Jeff J.
name: Breivik, Katelyn
name: Chawla, Chirag
name: Rodriguez, Carl
name: Chatterjee, Sourav
Publisher: name: arXiv
Year: 2021
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: Over the course of several years, stars trace helical trajectories as they traverse across the sky due to the combined effects of proper motion and parallax. It is well known that the gravitational pull of an unseen companion can cause deviations to these tracks. Several studies have pointed out that the astrometric mission Gaia will be able to identify a slew of new exoplanets, stellar binaries, and compact object companions with orbital periods as short as tens of days to as long as Gaia's lifetime. Here, we use mock astrometric observations to demonstrate that Gaia can identify and characterize black hole companions to luminous stars with orbital periods longer than Gaia's lifetime. Such astrometric binaries have orbital periods too long to exhibit complete orbits, and instead are identified through curvature in their characteristic helical paths. By simultaneously measuring the radius of this curvature and the orbital velocity, constraints can be placed on the underlying orbit. We quantify the precision with which Gaia can measure orbital accelerations and apply that to model predictions for the population of black holes orbiting stars in the stellar neighborhood. Although orbital degeneracies imply that many of the accelerations induced by hidden black holes could also be explained by faint low-mass stars, we discuss how the nature of certain putative black hole companions can be confirmed with high confidence using Gaia data alone.
description: 12 pages, 11 figures; submitted to AAS Journals; comments welcome