cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Quantum Dimensionality Reduction by Linear Discriminant Analysis
Creators: name: Yu, Kai
name: Guo, Gong-De
name: Lin, Song
Publisher: name: arXiv
Year: 2021
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Dimensionality reduction (DR) of data is a crucial issue for many machine learning tasks, such as pattern recognition and data classification. In this paper, we present a quantum algorithm and a quantum circuit to efficiently perform linear discriminant analysis (LDA) for dimensionality reduction. Firstly, the presented algorithm improves the existing quantum LDA algorithm to avoid the error caused by the irreversibility of the between-class scatter matrix $S_B$ in the original algorithm. Secondly, a quantum algorithm and quantum circuits are proposed to obtain the target state corresponding to the low-dimensional data. Compared with the best-known classical algorithm, the quantum linear discriminant analysis dimensionality reduction (QLDADR) algorithm has exponential acceleration on the number $M$ of vectors and a quadratic speedup on the dimensionality $D$ of the original data space, when the original dataset is projected onto a polylogarithmic low-dimensional space. Moreover, the target state obtained by our algorithm can be used as a submodule of other quantum machine learning tasks. It has practical application value of make that free from the disaster of dimensionality.
Thermodynamic insights into the intricate magnetic phase diagram of EuAl$_{4}$
Creators: name: Meier, William R.
name: Torres, James R.
name: Hermann, Raphael P.
name: Zhao, Jiyong
name: Lavina, Barbara
name: Sales, Brian C.
name: May, Andrew F.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: The tetragonal intermetallic compound EuAl$_{4}$ hosts an exciting variety of low temperature phases. In addition to a charge density wave below 140 K, four ordered magnetic phases are observed below 15.4 K. Recently, a skyrmion phase was proposed based on Hall effect measurements under a $c$-axis magnetic field. We present a detailed investigation of the phase transitions in EuAl$_{4}$ under $c$-axis magnetic field. Our dilatometry, heat capacity, DC magnetometry, AC magnetic susceptibility, and resonant ultrasound spectroscopy measurements reveal three magnetic phase transitions not previously reported. We discuss what our results reveal about the character of the magnetic phases. Our first key result is a detailed $H \parallel [001]$ magnetic phase diagram mapping the seven phases we observe. Second, we identify a new high-field phase, phase VII, which directly corresponds to the region were skyrmions have been suggested. Our results provide guidance for future studies exploring the complex magnetic interactions and spin structures in EuAl$_{4}$.
description: 20 pages, 15 figures
Quantum K-nearest neighbor classification algorithm based on Hamming distance
Creators: name: Li, Jing
name: Lin, Song
name: Kai, Yu
name: Guo, Gongde
Publisher: name: arXiv
Year: 2021
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: K-nearest neighbor classification algorithm is one of the most basic algorithms in machine learning, which determines the sample's category by the similarity between samples. In this paper, we propose a quantum K-nearest neighbor classification algorithm with Hamming distance. In this algorithm, quantum computation is firstly utilized to obtain Hamming distance in parallel. Then, a core sub-algorithm for searching the minimum of unordered integer sequence is presented to find out the minimum distance. Based on these two sub-algorithms, the whole quantum frame of K-nearest neighbor classification algorithm is presented. At last, it is shown that the proposed algorithm can achieve a quadratical speedup by analyzing its time complexity briefly.
description: 8 pages,5 figures
Physical Regimes of Electrostatic Wave-Wave nonlinear interactions generated by an Electron Beam Propagating in a Background Plasma
Creators: name: Sun, Haomin
name: Chen, Jian
name: Kaganovich, Igor D.
name: Khrabrov, Alexander
name: Sydorenko, Dmytro
Publisher: name: arXiv
Year: 2022
Subjects: subject: Plasma Physics (physics.plasm-ph)
subject: Space Physics (physics.space-ph)
subject: FOS: Physical sciences

description: Electron-beam plasma interaction has long been a topic of great interest. Despite the success of Quasi-Linear (QL) theory and Weak Turbulence (WT) theory, their validities are limited by the requirement of sufficiently dense mode spectrum and small wave amplitude. In this paper, we extensively studied the collective processes of a mono-energetic electron beam emitted from a thermionic cathode propagating through a cold plasma by performing a large number of high resolution two-dimensional (2D) particle-in-cell (PIC) simulations and using analytical theories. We confirm that the initial stage of two-stream instability is saturated due to well-known wave-trapping mechanism. Further evolution occurs due to strong wave-wave nonlinear processes. We show that the beam-plasma interaction can be classified into four different physical regimes in the parameter space for the plasma and beam parameters. The differences between the different regimes are analyzed in detail. For the first time, we identified a new regime in strong Langmuir turbulence featured by what we call Electron Modulational Instability (EMI) that could create a local Langmuir wave packet growing faster than the ion plasma frequency. Ions do not have time to respond to EMI in the initial growing stage. On a longer timescale, the action of the ponderomotive force produces very strong ion density perturbations, and eventually the beam-plasma wave interaction stops being resonant due to strong ion density perturbations. Consequently, in this EMI regime, electron beam-plasma interaction occurs in a periodic (intermittent) process. The beams are strongly scattered by waves, and the Langmuir wave spectrum is significantly broadened, which in turn gives rise to strong heating of bulk electrons. A resulting kappa distribution and a wave-energy spectrum, E^2 (k)~k^(-5), are observed in the strong turbulent regime.
description: 71 pages, 20 figures
Electron Modulational Instability in the Strong Turbulent Regime for an Electron Beam Propagating in Background Plasma
Creators: name: Sun, Haomin
name: Chen, Jian
name: Kaganovich, Igor D.
name: Khrabrov, Alexander
name: Sydorenko, Dmytro
Publisher: name: arXiv
Year: 2022
Subjects: subject: Plasma Physics (physics.plasm-ph)
subject: Space Physics (physics.space-ph)
subject: FOS: Physical sciences

description: We study collective processes for an electron beam propagating through a background plasma using simulations and analytical theory. A new regime where the instability of a Langmuir wave packet can grow locally much faster than ion frequency is clearly identified. The key feature of this new regime is an Electron Modulational Instability that rapidly creates a local Langmuir wave packet, which in its turn produces local charge separation and strong ion density perturbations because of the action of the ponderomotive force, such that the beam-plasma wave interaction stops being resonant. Three evolution stages of the process and observed periodic burst features are discussed. Different physical regimes in the plasma and beam parameter space are demonstrated for the first time.
description: 20 pages, 3 figures
Multi-party quantum key agreement protocol with authentication
Creators: name: Wu, Yiting
name: Chang, Hong
name: Guo, Gongde
name: Lin, Song
Publisher: name: arXiv
Year: 2021
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Utilizing the advantage of quantum entanglement swapping, a multi-party quantum key agreement protocol with authentication is proposed. In this protocol, a semi-trusted third party is introduced, who prepares Bell states, and sends one particle to multiple participants respectively. After that the participants can share a Greenberger-Horne-Zeilinger state by entanglement swapping. Finally, these participants measure the particles in their hands and obtain an agreement key. Here, classical hash function and Hadamard operation are utilized to authenticate the identity of participants. The correlations of GHZ states ensure the security of the proposed protocol. To illustrated it detailly, the security of this protocol against common attacks is analyzed, which shows that the proposed protocol is secure in theory.
Towards Universal Axion Inflation and Reheating in String Theory
Creators: name: Blumenhagen, Ralph
name: Plauschinn, Erik
Publisher: name: arXiv
Year: 2014
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: The recent BICEP2 measurements of B-modes indicate a large tensor-to-scalar ratio in inflationary cosmology, which points towards trans-Planckian evolution of the inflaton. We propose possible string-theory realizations thereof. Schemes for natural and axion monodromy inflation are presented in the framework of the type IIB large volume scenario. The inflaton in both cases is given by the universal axion and its potential is generated at subleading order by F-terms. Our models are shown to feature a natural mechanism for inflaton decay into predominantly Standard Model particles.
description: 7 pages; v2: references and one paragraph added; v3: minor changes in section 4
An integration by parts formula for the bilinear form of the hypersingular boundary integral operator for the transient heat equation in three spatial dimensions
Creators: name: Watschinger, Raphael
name: Of, Günther
Publisher: name: arXiv
Year: 2021
Subjects: subject: Numerical Analysis (math.NA)
subject: FOS: Mathematics
subject: 65M38, 45E10

description: While an integration by parts formula for the bilinear form of the hypersingular boundary integral operator for the transient heat equation in three spatial dimensions is available in the literature, a proof of this formula seems to be missing. Moreover, the available formula contains an integral term including the time derivative of the fundamental solution of the heat equation, whose interpretation is difficult at second glance. To fill these gaps we provide a rigorous proof of a general version of the integration by parts formula and an alternative representation of the mentioned integral term, which is valid for a certain class of functions including the typical tensor-product discretization spaces.
Code Search: A Survey of Techniques for Finding Code
Creators: name: Di Grazia, Luca
name: Pradel, Michael
Publisher: name: arXiv
Year: 2022
Subjects: subject: Software Engineering (cs.SE)
subject: FOS: Computer and information sciences

description: The immense amounts of source code provide ample challenges and opportunities during software development. To handle the size of code bases, developers commonly search for code, e.g., when trying to find where a particular feature is implemented or when looking for code examples to reuse. To support developers in finding relevant code, various code search engines have been proposed. This article surveys 30 years of research on code search, giving a comprehensive overview of challenges and techniques that address them. We discuss the kinds of queries that code search engines support, how to preprocess and expand queries, different techniques for indexing and retrieving code, and ways to rank and prune search results. Moreover, we describe empirical studies of code search in practice. Based on the discussion of prior work, we conclude the article with an outline of challenges and opportunities to be addressed in the future.
Total positivity of some polynomial matrices that enumerate labeled trees and forests, I. Forests of rooted labeled trees
Creators: name: Sokal, Alan D.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Combinatorics (math.CO)
subject: Classical Analysis and ODEs (math.CA)
subject: FOS: Mathematics
subject: 05A15 (Primary), 05A19, 05A20, 05C05, 05C30, 15B05, 15B36, 15B48, 30E05, 44A60 (Secondary)

description: We consider the lower-triangular matrix of generating polynomials that enumerate $k$-component forests of rooted trees on the vertex set $[n]$ according to the number of improper edges (generalizations of the Ramanujan polynomials). We show that this matrix is coefficientwise totally positive and that the sequence of its row-generating polynomials is coefficientwise Hankel-totally positive. More generally, we define the generic rooted-forest polynomials by introducing also a weight $m! \, ϕ_m$ for each vertex with $m$ proper children. We show that if the weight sequence $ϕ$ is Toeplitz-totally positive, then the two foregoing total-positivity results continue to hold. Our proofs use production matrices and exponential Riordan arrays.
description: LaTex2e, 65 pages. arXiv admin note: text overlap with arXiv:1907.02645. Version 2 makes some minor changes. To be published in Monatshefte f\"ur Mathematik
Tensor train based isogeometric analysis for PDE approximation on parameter dependent geometries
Creators: name: Ion, Ion Gabriel
name: Loukrezis, Dimitrios
name: De Gersem, Herbert
Publisher: name: arXiv
Year: 2022
Subjects: subject: Numerical Analysis (math.NA)
subject: FOS: Mathematics

description: This work develops a numerical solver based on the combination of isogeometric analysis (IGA) and the tensor train (TT) decomposition for the approximation of partial differential equations (PDEs) on parameter-dependent geometries. First, the discrete Galerkin operator as well as the solution for a fixed geometry configuration are represented as tensors and the TT format is employed to reduce their computational complexity. Parametric dependencies are included by considering the parameters that control the geometry configuration as additional dimensions next to the physical space coordinates. The parameters are easily incorporated within the TT-IGA solution framework by introducing a tensor product basis expansion in the parameter space. The discrete Galerkin operators are accordingly extended to accommodate the parameter dependence, thus obtaining a single system that includes the parameter dependency. The system is solved directly in the TT format and a low-rank representation of the parameter-dependent solution is obtained. The proposed TT-IGA solver is applied to several test cases which showcase its high computational efficiency and tremendous compression ratios achieved for representing the parameter-dependent IGA operators and solutions.
description: Submitted manuscript
Ångström-scale chemically powered motors
Creators: name: Colberg, Peter H.
name: Kapral, Raymond
Publisher: name: arXiv
Year: 2014
Subjects: subject: Soft Condensed Matter (cond-mat.soft)
subject: FOS: Physical sciences

description: Like their larger micron-scale counterparts, Ångström-scale chemically self-propelled motors use asymmetric catalytic activity to produce self-generated concentration gradients that lead to directed motion. Unlike their micron-scale counterparts, the sizes of Ångström-scale motors are comparable to the solvent molecules in which they move, they are dominated by fluctuations, and they operate on very different time scales. These new features are studied using molecular dynamics simulations of small sphere dimer motors. We show that the ballistic regime is dominated by the thermal speed but the diffusion coefficients of these motors are orders of magnitude larger than inactive dimers. Such small motors may find applications in nano-confined systems or perhaps eventually in the cell.
description: 6 pages, 8 figures
Towards interferometry of neutrino electromagnetism
Creators: name: Petropavlova, Mariia
name: Smetana, Adam
Publisher: name: arXiv
Year: 2022
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: It is predicted within the Standard Model of elementary particles that asymmetric neutrino environments cause rotation of linear polarization of electromagnetic wave -- the birefringence. We demonstrate that this effect is strongly enhanced if additionally the photon is propagating through refractive medium, which effectively increases the photon exposure to the neutrino medium. Our estimate for infrared laser beam in $1\,\mathrm{m}$ long optical fiber exposed to reactor anti-neutrino flux results in linear polarization rotation by the angle $\sim4.6\times10^{-39}\,\mathrm{rad}$. We also derive the proper dependence of the effect on the angle between the directions of photon and neutrino propagation in the laboratory frame. For that purpose we derive the correct form of the basis of polarization four-vectors, which differs from the one widely used in literature. We also estimate the sub-leading optical effect of the neutrino medium due to the neutrino dipole magnetic moment, in terms of a variation of the refractive index and its angular dependence. A rough monochromatic approximation points towards the existence of a resonant enhancement of the effect.
description: 6 pages, 1 figure
Efficient Off-Policy Q-Learning for Data-Based Discrete-Time LQR Problems
Creators: name: Lopez, Victor G.
name: Alsalti, Mohammad
name: Müller, Matthias A.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Systems and Control (eess.SY)
subject: FOS: Electrical engineering, electronic engineering, information engineering

description: This paper introduces and analyzes an improved Q-learning algorithm for discrete-time linear time-invariant systems. The proposed method does not require any knowledge of the system dynamics, and it enjoys significant efficiency advantages over other data-based optimal control methods in the literature. This algorithm can be fully executed off-line, as it does not require to apply the current estimate of the optimal input to the system as in on-policy algorithms. It is shown that a persistently exciting input, defined from an easily tested matrix rank condition, guarantees the convergence of the algorithm. A data-based method is proposed to design the initial stabilizing feedback gain that the algorithm requires. Robustness of the algorithm in the presence of noisy measurements is analyzed. We compare the proposed algorithm in simulation to different direct and indirect data-based control design methods.
description: 12 pages, journal article
Higgs inflation at the critical point
Creators: name: Bezrukov, Fedor
name: Shaposhnikov, Mikhail
Publisher: name: arXiv
Year: 2014
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: Higgs inflation can occur if the Standard Model (SM) is a self-consistent effective field theory up to inflationary scale. This leads to a lower bound on the Higgs boson mass, $M_h \geq M_{\text{crit}}$. If $M_h$ is more than a few hundreds of MeV above the critical value, the Higgs inflation predicts the universal values of inflationary indexes, $r\simeq 0.003$ and $n_s\simeq 0.97$, independently on the Standard Model parameters. We show that in the vicinity of the critical point $M_{\text{crit}}$ the inflationary indexes acquire an essential dependence on the mass of the top quark $m_t$ and $M_h$. In particular, the amplitude of the gravitational waves can exceed considerably the universal value.
description: Improved analysis taking into account one-loop terms in the effective potential. Sign error in the formula for the running of the spectral index corrected. Discussion of the relation between the particle physics and inflationary parameters added
واقع النشر العلمي الاجتماعي في دولة الإمارات العربية المتحدة: دراسة تحليلية لدورية شؤون اجتماعية
Creators: name: محمد صلاح الدين محمد مضوي
name: Mudawi, Mohamed Salah Eldin
Publisher: name: Zenodo
Year: 2018
Subjects: النشر العلمي
العلوم الاجتماعية
جمعية الاجتماعيين
المجلات المحكمة
دولة الإمارات العربية المتحدة
مجلة شؤون اجتماعية
معامل التأثير
Impact factor
Scholarly journals

description: ورقة علمية (عرض تقديمي) حول واقع النشر العلمي الاجتماعي في دولة الإمارات العربية المتحدة: دراسة تحليلية لدورية شؤون اجتماعية. قدمت الورقة ضمن وقائع المؤتمر الدولي الثالث لمعامل التأثير العربي: واقع النشر العلمي في العالم العربي المنعقد بتاريخ 29 -30 يونيو في مدينة دبي دولة الإمارات العربية المتحدة A paper presented at the 3rd International Conference on Arab Impact Factor, held in Dubai, United Arab Emirates June 29-30, 2018. The paper title: Scholarly publishing in social sciences in the United Arab Emirates: An analytical study of the Social Affairs Journal.
Text mining and sentiment analysis of COVID-19 tweets
Creators: name: Zhang, Qihuang
name: Yi, Grace Y.
name: Chen, Li-Pang
name: He, Wenqing
Publisher: name: arXiv
Year: 2021
Subjects: subject: Social and Information Networks (cs.SI)
subject: Applications (stat.AP)
subject: FOS: Computer and information sciences

description: The human severe acute respiratory syndrome coronavirus 2 (SARS-Cov-2), causing the COVID-19 disease, has continued to spread all over the world. It menacingly affects not only public health and global economics but also mental health and mood. While the impact of the COVID-19 pandemic has been widely studied, relatively fewer discussions about the sentimental reaction of the population have been available. In this article, we scrape COVID-19 related tweets on the microblogging platform, Twitter, and examine the tweets from Feb~24, 2020 to Oct~14, 2020 in four Canadian cities (Toronto, Montreal, Vancouver, and Calgary) and four U.S. cities (New York, Los Angeles, Chicago, and Seattle). Applying the Vader and NRC approaches, we evaluate the sentiment intensity scores and visualize the information over different periods of the pandemic. Sentiment scores for the tweets concerning three anti-epidemic measures, masks, vaccine, and lockdown, are computed for comparisons. The results of four Canadian cities are compared with four cities in the United States. We study the causal relationships between the infected cases, the tweet activities, and the sentiment scores of COVID-19 related tweets, by integrating the echo state network method with convergent cross-mapping. Our analysis shows that public sentiments regarding COVID-19 vary in different time periods and locations. In general, people have a positive mood about COVID-19 and masks, but negative in the topics of vaccine and lockdown. The causal inference shows that the sentiment influences people's activities on Twitter, which is also correlated to the daily number of infections.
description: 20 pages, 10 figures, 1 table
The ESCAPE project - Tutorial on FAIR data with Multi-Order Coverage maps
Creators: name: Amodeo, Stefania
Publisher: name: Zenodo
Year: 2022

description: ESCAPE (European Science Cluster of Astronomy & Particle physics ESFRI research infrastructures) is a project funded by the by the European Union’s Horizon 2020 program that brings together astronomy, astroparticle and particle physics communities to address the challenges of open science and long-term data usability. I will give an overview of the project and I will present the activities being implemented for integrating the ESFRI facilities and other partner research infrastructures into the European Open Science Cloud through the Virtual Observatory framework. Finally, I will provide a notebook tutorial to demonstrate the interoperability of the Multi Order Coverage (MOC) map, an efficient data structure for describing and manipulating sky coverages of astronomical surveys, recently approved as IVOA standard and extended within ESCAPE to support both spatial and temporal coverages for multi-wavelength a multi-messenger observations.
description: The tutorial can be found on the CDS GitHub repository: https://github.com/cds-astro/tutorials/blob/master/Past_Conferences_and_Schools/2022_ROSA/MOCpy_tutorial_ROSA2022.ipynb
Finite N and the failure of bulk locality: Black holes in AdS/CFT
Creators: name: Kabat, Daniel
name: Lifschytz, Gilad
Publisher: name: arXiv
Year: 2014
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We consider bulk quantum fields in AdS/CFT in the background of an eternal black hole. We show that for black holes with finite entropy, correlation functions of semiclassical bulk operators close to the horizon deviate from their semiclassical value and are ill-defined inside the horizon. This is due to the large-time behavior of correlators in a unitary CFT, and means the region near and inside the horizon receives corrections. We give a prescription for modifying the definition of a bulk field in a black hole background, such that one can still define operators that mimic the inside of the horizon, but at the price of violating microcausality. For supergravity fields we find that commutators at spacelike separation generically ~ exp(-S/2). Similar results hold for stable black holes that form in collapse. The general lesson may be that a small amount of non-locality, even over arbitrarily large spacelike distances, is an essential aspect of non-perturbative quantum gravity.
description: 43 pages, 7 figures. v2: additional appendix on finite-entropy correlators, additional references, version to appear in JHEP
Probing magnetic anisotropy and spin-reorientation transition in 3D antiferromagnet, Ho$_{0.5}$Dy$_{0.5}$FeO$_{3}\vert$Pt using spin Hall magnetoresistance
Creators: name: Wagh, Aditya A.
name: Garg, Priyanka
name: Haldar, Arijit
name: Mallick, Kingshuk
name: Chakraborty, Tirthankar
name: Elizabeth, Suja
name: Kumar, P. S. Anil
Publisher: name: arXiv
Year: 2022
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: Orthoferrites ($RE$FeO$_{3}$) containing rare-earth ($RE$) elements are 3D antiferromagnets (AFM) that exhibit characteristic weak ferromagnetism originating due to slight canting of the spin moments and display a rich variety of spin reorientation transitions in the magnetic field ($H$)-temperature ($T$) parameter space. We present spin Hall magnetoresistance (SMR) studies on a $b$-plate ($ac$-plane) of crystalline Ho$_{0.5}$Dy$_{0.5}$FeO$_{3}|$Pt (HDFO$|$Pt) hybrid at various $T$ in the range, 11 to 300 K. In the room temperature $Γ_4(G_x, A_y, F_z)$ phase, the switching between two degenerate domains, $Γ_4(+G_x, +F_z)$ and $Γ_4(-G_x, -F_z)$ occurs at fields above a critical value, $H_{\text{c}} \approx 713$ Oe. Under $H > H_{\text{c}}$, the angular dependence of SMR ($α$-scan) in the $Γ_4(G_x, A_y, F_z)$ phase yielded a highly skewed curve with a sharp change (sign-reversal) along with a rotational hysteresis around $a$-axis. This hysteresis decreases with an increase in $H$. Notably, at $H < H_{\text{c}} $, the $α$-scan measurements on the single domain, $Γ_4(\pm G_x, \pm F_z)$ exhibited an anomalous sinusoidal signal of periodicity 360 deg. Low-$T$ SMR curves ($H$ = 2.4 kOe), showed a systematic narrowing of the hysteresis (down to 150 K) and a gradual reduction in the skewness (150 to 52 K), suggesting weakening of the anisotropy possibly due to the $T$-evolution of Fe-$RE$ exchange coupling. Below 25 K, the SMR modulation showed an abrupt change around the $c$-axis, marking the presence of $Γ_2(F_x,C_y,G_z)$ phase. We have employed a simple Hamiltonian and computed SMR to examine the observed skewed SMR modulation. In summary, SMR is found to be an effective tool to probe magnetic anisotropy as well as a spin reorientation in HDFO. Our spin-transport study highlights the potential of HDFO for future AFM spintronic devices.
description: 12 pages, 7 figures
Twisted geometry coherent states in all dimensional loop quantum gravity: II. Ehrenfest Property
Creators: name: Long, Gaoping
Publisher: name: arXiv
Year: 2022
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences

description: In the preceding paper of this series of articles we constructed the twisted geometry coherent states in all dimensional loop quantum gravity and established their peakedness properties. In this paper we establish the "Ehrenfest property" of these coherent states which are labelled by the twisted geometry parameters. By this we mean that the expectation values of the polynomials of the elementary operators as well as the operators which are not polynomial functions of the elementary operators, reproduce, to zeroth order in $\hbar$, the values of the corresponding classical functions at the twisted geometry space point where the coherent state is peaked.
Sharp quantitative Faber-Krahn inequalities and the Alt-Caffarelli-Friedman monotonicity formula
Creators: name: Allen, Mark
name: Kriventsov, Dennis
name: Neumayer, Robin
Publisher: name: arXiv
Year: 2021
Subjects: subject: Analysis of PDEs (math.AP)
subject: FOS: Mathematics
subject: 47A75, 49Q20, 42B37

description: The objective of this paper is two-fold. First, we establish new sharp quantitative estimates for Faber-Krahn inequalities on simply connected space forms. We prove that the gap between the first eigenvalue of a given set $Ω$ and that of the ball quantitatively controls both the $L^1$ distance of this set from a ball {\it and} the $L^2$ distance between the corresponding eigenfunctions: \[ λ_1(Ω) - λ_1(B) \gtrsim |ΩΔB|^2 + \int |u_Ω - u_B|^2, \] where $B$ denotes the nearest geodesic ball to $Ω$ with $|B|=|Ω|$ and $u_Ω$ denotes the first eigenfunction with suitable normalization. On Euclidean space, this extends a result of Brasco-De Phillipis-Velichkov; the eigenfunction control largely builds upon new regularity results for minimizers of critically perturbed Alt-Cafarelli type functionals in our companion paper. On the round sphere and hyperbolic space, the present results are the first sharp quantitative results with respect to any distance; here the local portion of the analysis is based on new implicit spectral analysis techniques. Second, we apply these sharp quantitative Faber-Krahn inequalities in order to establish a quantitative form of the Alt-Caffarelli-Friedman (ACF) monotonicity formula. We show that the energy drop in the ACF monotonicity formula from one scale to the next controls how close a pair of admissible functions is from a pair of complementary half-plane solutions. In particular, when the square root of the energy drop summed over all scales is small, our result implies the existence of tangents (unique blowups) of these functions.
description: Final version for publication
Radiative hadronization: Photon emission at hadronization from quark-gluon plasma
Creators: name: Fujii, Hirotsugu
name: Itakura, Kazunori
name: Miyachi, Katsunori
name: Nonaka, Chiho
Publisher: name: arXiv
Year: 2022
Subjects: subject: Nuclear Theory (nucl-th)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: Nuclear Experiment (nucl-ex)
subject: FOS: Physical sciences

description: We investigate photon emission at the hadronization stage from a quark-gluon plasma created in relativistic heavy-ion collisions. A recombination-model picture suggests that a quark and an antiquark bind into a meson state in hadronization, which would apparently violate the energy conservation if there is nothing else involved. We consider here a hadronization process where the recombination accompanies a photon emission. This is an analog of the "{\it radiative recombination}" known in plasma physics, such as $e^- + p^+ \to {\rm H}^0 +γ$, which occurs when an electromagnetic plasma goes back to a neutral atomic gas. The "radiative hadronization" picture will bring about (i) an enhancement of the photon yield, (ii) significant flow of photons similar to that of hadrons, and (iii) the photon transverse momentum ($p_T$) distribution with a thermal profile whose effective temperature is given by blue-shifted temperature of quarks. Here as a simplest and phenomenological realization of the radiative hadronization, we modify the recombination model to involve a photon emission and evaluate the photon yield with this modified model. Adding this contribution to the direct photon yield along with thermal photon contribution calculated with a hydrodynamic model and a parametrized contribution of prompt photons, we study the $p_T$ spectrum and elliptic flow of the photons produced in heavy-ion collisions at RHIC and LHC energies.
description: 25 pages, 15 figures (Appendix C with Fig.15 is added)
Analytic characterization of monotone Hopf-harmonics
Creators: name: Kangasniemi, Ilmari
name: Koski, Aleksis
name: Onninen, Jani
Publisher: name: arXiv
Year: 2021
Subjects: subject: Analysis of PDEs (math.AP)
subject: Complex Variables (math.CV)
subject: FOS: Mathematics
subject: 31C45 (Primary) 35J25, 58E20, 74B20, 46E35 (Secondary)

description: We study solutions of the inner-variational equation associated with the Dirichlet energy in the plane, given homeomorphic Sobolev boundary data. We prove that such a solution is monotone if and only if its Jacobian determinant does not change sign. These solutions, called monotone Hopf-harmonics, are a natural alternative to harmonic homeomorphisms. Examining the topological behavior of a solution (not a priori monotone) on the trajectories of Hopf quadratic differentials plays a sizable role in our arguments.
description: 27 pages, 1 figure
Planet formation from the ejecta of common envelopes
Creators: name: Schleicher, Dominik R. G.
name: Dreizler, Stefan
Publisher: name: arXiv
Year: 2013
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: The close binary system NN Serpentis must have gone through a common envelope phase before the formation of its white dwarf. During this phase, a substantial amount of mass was lost from the envelope. The recently detected orbits of circumbinary planets are likely inconsistent with planet formation before the mass loss.We explore whether new planets may have formed from the ejecta of the common envelope and derive the expected planetary mass as a function of radius.We employed the Kashi & Soker model to estimate the amount of mass that is retained during the ejection event and inferred the properties of the resulting disk from the conservation of mass and angular momentum. The resulting planetary masses were estimated from models with and without radiative feedback. We show that the observed planetary masses can be reproduced for appropriate model parameters. Photoheating can stabilize the disks in the interior, potentially explaining the observed planetary orbits on scales of a few AU. We compare the expected mass scale of planets for 11 additional systems with observational results and find hints of two populations, one consistent with planet formation from the ejecta of common envelopes and the other a separate population that may have formed earlier. The formation of the observed planets from the ejecta of common envelopes seems feasible. The model proposed here can be tested through refined observations of additional post-common envelope systems. While it appears observationally challenging to distinguish between the accretion on pre-existing planets and their growth from new fragments, it may be possible to further constrain the properties of the protoplanetary disk through additional observations of current planetary candidates and post-common envelope binary systems.
description: 12 pages, 8 figures, 3 tables. Accepted at A&A
Half-sibling regression meets exoplanet imaging: PSF modeling and subtraction using a flexible, domain knowledge-driven, causal framework
Creators: name: Gebhard, Timothy D.
name: Bonse, Markus J.
name: Quanz, Sascha P.
name: Schölkopf, Bernhard
Publisher: name: arXiv
Year: 2022
Subjects: subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: Machine Learning (cs.LG)
subject: FOS: Physical sciences
subject: FOS: Computer and information sciences

description: High-contrast imaging of exoplanets hinges on powerful post-processing methods to denoise the data and separate the signal of a companion from its host star, which is typically orders of magnitude brighter. Existing post-processing algorithms do not use all prior domain knowledge that is available about the problem. We propose a new method that builds on our understanding of the systematic noise and the causal structure of the data-generating process. Our algorithm is based on a modified version of half-sibling regression (HSR), a flexible denoising framework that combines ideas from the fields of machine learning and causality. We adapt the method to address the specific requirements of high-contrast exoplanet imaging data obtained in pupil tracking mode. The key idea is to estimate the systematic noise in a pixel by regressing the time series of this pixel onto a set of causally independent, signal-free predictor pixels. We use regularized linear models in this work; however, other (non-linear) models are also possible. In a second step, we demonstrate how the HSR framework allows us to incorporate observing conditions such as wind speed or air temperature as additional predictors. When we apply our method to four data sets from the VLT/NACO instrument, our algorithm provides a better false-positive fraction than PCA-based PSF subtraction, a popular baseline method in the field. Additionally, we find that the HSR-based method provides direct and accurate estimates for the contrast of the exoplanets without the need to insert artificial companions for calibration in the data sets. Finally, we present first evidence that using the observing conditions as additional predictors can improve the results. Our HSR-based method provides an alternative, flexible and promising approach to the challenge of modeling and subtracting the stellar PSF and systematic noise in exoplanet imaging data.
description: Accepted for publication in Astronomy & Astrophysics
Hydrocarbon and Reservoir Mapping Using Seismic Simulated Annealing Inversion, in Southern Pattani Basin, Gulf of Thailand
Creators: name: Egi Ramdhani
Publisher: name: Department of Geology, Chulalongkorn University
Year: 2020
Subjects: Post-stack seismic inversion, Simulated annealing inversion, Reservoir imaging, Pattani Basin, Gulf of Thailand

description: Bulletin of Earth Sciences of Thailand (BEST), 12, 2, 12-Jan
An Eulerian-Lagrangian Runge-Kutta finite volume (EL-RK-FV) method for solving convection and convection-diffusion equations
Creators: name: Nakao, Joseph
name: Chen, Jiajie
name: Qiu, Jingmei
Publisher: name: arXiv
Year: 2022
Subjects: subject: Numerical Analysis (math.NA)
subject: FOS: Mathematics
subject: 65M08, 65M20, 65M22

description: We propose a new Eulerian-Lagrangian Runge-Kutta finite volume method for numerically solving convection and convection-diffusion equations. Eulerian-Lagrangian and semi-Lagrangian methods have grown in popularity mostly due to their ability to allow large time steps. Our proposed scheme is formulated by integrating the PDE on a space-time region partitioned by approximations of the characteristics determined from the Rankine-Hugoniot jump condition; and then rewriting the time-integral form into a time differential form to allow application of Runge-Kutta (RK) methods via the method-of-lines approach. The scheme can be viewed as a generalization of the standard Runge-Kutta finite volume (RK-FV) scheme for which the space-time region is partitioned by approximate characteristics with zero velocity. The high-order spatial reconstruction is achieved using the recently developed weighted essentially non-oscillatory schemes with adaptive order (WENO-AO); and the high-order temporal accuracy is achieved by explicit RK methods for convection equations and implicit-explicit (IMEX) RK methods for convection-diffusion equations. Our algorithm extends to higher dimensions via dimensional splitting. Numerical experiments demonstrate our algorithm's robustness, high-order accuracy, and ability to handle extra large time steps.
description: 35 pages, 21 figures, submitted to the Journal of Computational Physics
High-Resolution Mapping of Plio-Pleistocene Reservoir Depositional Facies in Zawtika Gas Field, Gulf of Moattama, Using Stratal-Slicing Techniques and Attribute Analysis
Creators: name: Luptawan Intasorn
Publisher: name: Department of Geology, Chulalongkorn University
Year: 2020
Subjects: Horizon stack attribute, Biogenic gas, Plio-Pleistocene reservoir, tidal influenced delta

description: Bulletin of Earth Sciences of Thailand (BEST), 12, 2, 13-24
Improving Deep Learning for HAR with shallow LSTMs
Creators: name: Bock, Marius
name: Hoelzemann, Alexander
name: Moeller, Michael
name: Van Laerhoven, Kristof
Publisher: name: arXiv
Year: 2021
Subjects: subject: Human-Computer Interaction (cs.HC)
subject: Machine Learning (cs.LG)
subject: FOS: Computer and information sciences

description: Recent studies in Human Activity Recognition (HAR) have shown that Deep Learning methods are able to outperform classical Machine Learning algorithms. One popular Deep Learning architecture in HAR is the DeepConvLSTM. In this paper we propose to alter the DeepConvLSTM architecture to employ a 1-layered instead of a 2-layered LSTM. We validate our architecture change on 5 publicly available HAR datasets by comparing the predictive performance with and without the change employing varying hidden units within the LSTM layer(s). Results show that across all datasets, our architecture consistently improves on the original one: Recognition performance increases up to 11.7% for the F1-score, and our architecture significantly decreases the amount of learnable parameters. This improvement over DeepConvLSTM decreases training time by as much as 48%. Our results stand in contrast to the belief that one needs at least a 2-layered LSTM when dealing with sequential data. Based on our results we argue that said claim might not be applicable to sensor-based HAR.
description: 6 pages, 2 figures, accepted at ISWC 21: International Symposium on Wearable Computer, Sept, 2021
Dynamical detection of three triple stellar systems in open clusters
Creators: name: Gonzalez, J. F.
name: Veramendi, M. E.
name: Cowley, C. R.
Publisher: name: arXiv
Year: 2014
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: We present a kinematic analysis of three triple stellar systems belonging to two open clusters: CPD-60°961 and HD66137 in NGC2516, and HD315031 in NGC6530. All three systems are hierarchical triples with a close binary bound to a third body in a wider orbit, whose presence is detected through velocity variations of the close binary barycentre. Orbital parameters are derived from radial velocity curves. Absolute parameters for all stars are estimated assuming cluster membership. Some dynamical and evolutionary aspects of these systems are discussed, particularly the possible influence of Kozai cycles. The two systems of NGC2516 have similar orbital configurations with inner periods of 11.23 d and 8.70 d and outer periods of 9.79 yr and 9.24 yr. We report also radial velocity measurements of the components of the visual binary CPD-60°944 in NGC2516. Including results from previous works, this cluster would harbor 5 hierarchical triples. The young system HD315031 has an inner binary with a period of 1.37 d and a very eccentric (e=0.85) outer orbit with a period of 483 d. Possible dynamical evolutionary scenarios are discussed. Long-term radial velocity monitoring is highlighted as strategy for the detection of subsystems with intermediate separations, which are hard to cover with normal spectroscopic studies or visual techniques.
description: 9 pages, 5 figures. Accepted by Monthly Notices of the Royal Astronomical Society
Statistics of Hierarchical Systems
Creators: name: Tokovinin, Andrei
Publisher: name: Zenodo
Year: 2023
Subjects: Multiple Stars
Binary Sars: Statistics

description: Statistics of hierarchical stellar system with 3 or more components is described by the number of components N, fractions of systems with different N, which strongly depends on the mass of primary component (14% of solar-type stars have N>2). Joint distributions of periods P, mass ratios, and eccentricites are of interest, although not accessible in practice. Crudely, a triple system can be viewed as two binaries. However, this simplistic model under-predicts triples and 2+2 quadruples and does not account for the preference of close (P<30 days) pairs to belong to hierarchies. An updated view of solar-type hierarchies within 100 pc, recently enhanced using Gaia, is presented; the 2208 known systems are still about 1/4 of their total estimated number. Distinctive families (populations) of hierarchies are tentatively identified in the multi-parameter space and illustrated by examples.
A Self-Consistent Model for Dust-Gas Coupling in Protoplanetary Disks
Creators: name: Batygin, Konstantin
name: Morbidelli, Alessandro
Publisher: name: arXiv
Year: 2022
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: Various physical processes that ensue within protoplanetary disks -- including vertical settling of icy/rocky grains, radial drift of solids, planetesimal formation, as well as planetary accretion itself -- are facilitated by hydrodynamic interactions between H/He gas and high-$Z$ dust. The Stokes number, which quantifies the strength of dust-gas coupling, thus plays a central role in protoplanetary disk evolution, and its poor determination constitutes an important source of uncertainty within the theory of planet formation. In this work, we present a simple model for dust-gas coupling, and demonstrate that for a specified combination of the nebular accretion rate, $\dot{M}$, and turbulence parameter, $α$, the radial profile of the Stokes number can be calculated uniquely. Our model indicates that the Stokes number grows sub-linearly with orbital radius, but increases dramatically across the water-ice line. For fiducial protoplanetary disk parameters of $\dot{M}=10^{-8}\,M_{\odot}/$year and $α=10^{-3}$, our theory yields characteristic values of the Stokes number on the order of $\mathrm{St}\sim10^{-4}$ (corresponding to $\sim$mm-sized silicate dust) in the inner nebula and $\mathrm{St}\sim10^{-1}$ (corresponding to $\sim$few-cm-sized icy grains), in the outer regions of the disk. Accordingly, solids are expected to settle into a thin sub-disk at large stellocentric distances, while remaining vertically well-mixed inside the ice line.
description: accepted for publication in Astronomy & Astrophysics