cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Bifurcation of the neuronal population dynamics of the modified theta model: transition to macroscopic gamma oscillation
Creators: name: Kotani, Kiyoshi
name: Akao, Akihiko
name: Chiba, Hayato
Publisher: name: arXiv
Year: 2020
Subjects: subject: Neurons and Cognition (q-bio.NC)
subject: Dynamical Systems (math.DS)
subject: Adaptation and Self-Organizing Systems (nlin.AO)
subject: FOS: Biological sciences
subject: FOS: Mathematics
subject: FOS: Physical sciences

description: Interactions of inhibitory neurons produce gamma oscillations (30--80 Hz) in the local field potential, which is known to be involved in functions such as cognition and attention. In this study, the modified theta model is considered to investigate the theoretical relationship between the microscopic structure of inhibitory neurons and their gamma oscillations under a wide class of distribution functions of tonic currents on individual neurons. The stability and bifurcation of gamma oscillations for the Vlasov equation of the model is investigated by the generalized spectral theory. It is shown that as a connection probability of neurons increases, a pair of generalized eigenvalues crosses the imaginary axis twice, which implies that a stable gamma oscillation exists only when the connection probability has a value within a suitable range. On the other hand, when the distribution of tonic currents on individual neurons is the Lorentzian distribution, the Vlasov equation is reduced to a finite dimensional dynamical system. The bifurcation analyses of the reduced equation exhibit equivalent results with the generalized spectral theory. It is also demonstrated that the numerical computations of neuronal population follow the analyses of the generalized spectral theory as well as the bifurcation analysis of the reduced equation.
Dark Energy and Neutrino CPT Violation
Creators: name: Gu, Pei-Hong
name: Bi, Xiao-Jun
name: Zhang, Xinmin
Publisher: name: arXiv
Year: 2005
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: In this paper we study the dynamical CPT violation in the neutrino sector induced by the dark energy of the Universe. Specifically we consider a dark energy model where the dark energy scalar derivatively interacts with the right-handed neutrinos. This type of derivative coupling leads to a cosmological CPT violation during the evolution of the background field of the dark energy. We calculate the induced CPT violation of left-handed neutrinos and find the CPT violation produced in this way is consistent with the present experimental limit and sensitive to the future neutrino oscillation experiments, such as the neutrino factory.
description: 10 pages, 2 figures. Typos corrected and references added. To be published in EPJC
การจำแนกพันธุ์มะม่วงในประเทศไทยจากลำดับดีเอ็นเอของยีน rpoC1 และ rbcL
Creators: name: ปิยดา บุสดี
name: ธีระชัย ธนานันต์
name: นฤมล ธนานันต์
Publisher: name: กองบริหารการวิจัย มหาวิทยาลัยธรรมศาสตร์
Year: 2558
Subjects: มะม่วง, ยีน rpoC1, ยีน rbcL, การจำแนกพันธุ์, ลำดับดีเอ็นเอ

description: 6, 23, วารสารวิทยาศาสตร์และเทคโนโลยี
Competing zero-field Chern insulators in Superconducting Twisted Bilayer Graphene
Creators: name: Stepanov, Petr
name: Xie, Ming
name: Taniguchi, Takashi
name: Watanabe, Kenji
name: Lu, Xiaobo
name: MacDonald, Allan H.
name: Bernevig, B. Andrei
name: Efetov, Dmitri K.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Superconductivity (cond-mat.supr-con)
subject: FOS: Physical sciences

description: The discovery of magic angle twisted bilayer graphene (MATBG) has unveiled a rich variety of superconducting, magnetic and topologically nontrivial phases. The existence of all these phases in one material, and their tunability, has opened new pathways for the creation of unusual gate tunable junctions. However, the required conditions for their creation - gate induced transitions between phases in zero magnetic field - have so far not been achieved. Here, we report on the first experimental demonstration of a device that is both a zero-field Chern insulator and a superconductor. The Chern insulator occurs near moire cell filling factor v = +1 in a hBN non-aligned MATBG device and manifests itself via an anomalous Hall effect. The insulator has Chern number C = +-1 and a relatively high Curie temperature of Tc = 4.5 K. Gate tuning away from this state exposes strong superconducting phases with critical temperatures of up to Tc = 3.5 K. In a perpendicular magnetic field above B > 0.5 T we observe a transition of the /C/= +1 Chern insulator from Chern number C = +-1 to C = 3, characterized by a quantized Hall plateau with Ryx = h/3e2. These observations show that interaction-induced symmetry breaking in MATBG leads to zero-field ground states that include almost degenerate and closely competing Chern insulators, and that states with larger Chern numbers couple most strongly to the B-field. By providing the first demonstration of a system that allows gate-induced transitions between magnetic and superconducting phases, our observations mark a major milestone in the creation of a new generation of quantum electronics.
TRANSLATE -- A Monte Carlo Simulation of Electron Transport in Liquid Argon
Creators: name: Beever, Zach
name: Caratelli, David
name: Fava, Angela
name: Pietropaolo, Francesco
name: Stocker, Francesca
name: Zettlemoyer, Jacob
Publisher: name: arXiv
Year: 2022
Subjects: subject: Instrumentation and Detectors (physics.ins-det)
subject: FOS: Physical sciences

description: The microphysics of electron and photon propagation in liquid argon is a key component of detector design and calibrations needed to construct and perform measurements within a wide range of particle physics experiments. As experiments grow in scale and complexity, and as the precision of their intended measurements increases, the development of tools to investigate important microphysics effects impacting such detectors becomes necessary. In this paper we present a new time-domain Monte Carlo simulation of electron transport in liquid argon. The simulation models the TRANSport in Liquid Argon of near-Thermal Electrons (TRANSLATE) with the aim of providing a multi-purpose software package for the study and optimization of detector environments, with a particular focus on ongoing and next generation liquid argon neutrino experiments utilizing the time projection chamber technology. TRANSLATE builds on previous work of Wojcik and Tachiya, amongst others, introducing additional cross-section processes up to ionization, thus modeling the full range of drift electron scattering interactions. The simulation is validated by benchmarking its performance with swarm parameters from data collected in experimental setups operating in gas and liquid.
description: 17 pages, 12 figures
การวิเคราะห์ความสัมพันธ์ทางพันธุกรรมของกล้วยไม้สกุลแวนด้าหมู่เข็มโดยใช้ลำดับนิวคลีโอไทด์ของยีน rbcLและชิ้นดีเอ็นเอที่อยู่ระหว่างยีน trnH กับ psbA
Creators: name: จินต์ ทองสม
name: ภัทรพร คุ้มภัย
name: ธีระชัย ธนานันต์
name: นฤมล ธนานันต์
Publisher: name: กองบริหารการวิจัย มหาวิทยาลัยธรรมศาสตร์
Year: 2558
Subjects: กล้วยไม้, สกุลแวนด้า, หมู่เข็ม, ความสัมพันธ์ทางพันธุกรรม, ลำดับนิวคลีโอไทด์

description: 6, 23, วารสารวิทยาศาสตร์และเทคโนโลยี
Prospects of constraining reionization model parameters using Minkowski tensors and Betti numbers
Creators: name: Kapahtia, Akanksha
name: Chingangbam, Pravabati
name: Ghara, Raghunath
name: Appleby, Stephen
name: Choudhury, Tirthankar Roy
Publisher: name: arXiv
Year: 2021
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We explore the possibility of constraining model parameters of the Epoch of Reionization (EoR) from 21cm brightness temperature maps, using a combination of morphological descriptors constructed from the eigenvalues of the Contour Minkowski Tensor (CMT), Betti numbers (count of connected regions $n_{con}$ and holes $n_{hole}$) and the area of structures in the excursion set of the field. We use a three parameter model of EoR simulated using 21\textrm{cmFAST}, namely the ionizing efficiency of sources $ζ$, the minimum virial temperature $T_{vir}$ required for collapse into a halo and the maximum radius for ionizing radiation described by $R_{mfp}$. We performed a Bayesian analysis to recover model parameters for a mock 21cm image from SKA phase I at a redshift of $z=7.4$ corresponding to a mean neutral hydrogen fraction of $\mathrm{\bar x}_{HI} \simeq 0.5$. We find that in the absence of noise the average size of structures in the field with $x_{HI} \lesssim 0.5$ is smaller than regions with $x_{HI} \gtrsim 0.5$ and the structures are equally isotropic when $\mathrm{\bar x}_{HI}=0.5$ . We also find that in order to recover the input model to within $1-σ$ accuracy for a mock noisy image at a single frequency channel of $1~\mathrm{MHz}$, for an observation time $t_{obs}<2000~\mathrm{hrs}$, the noisy $δT_b$ map needs to be smoothed at a scale $R_s>9.5~\mathrm{Mpc}$. Finally we show that the systematic behaviour of the statistic as ionization progresses, enables us to obtain stringent constraints on $\mathrm{\bar x}_{HI}$ (with a coefficient of variation $\sim 0.05$ as compared to $\sim 0.1-0.2$ for model parameter constraints), thereby making these descriptors a promising statistic for constraining EoR model parameters and the ionization history of the universe.
description: Accepted for publication in JCAP
การศึกษาสมรรถนะทางวัฒนธรรมของอาจารย์และนักศึกษา คณะพยาบาลศาสตร์ มหาวิทยาลัยธรรมศาสตร์
Creators: name: อังคณา จิรโรจน์
Publisher: name: กองบริหารการวิจัย มหาวิทยาลัยธรรมศาสตร์
Year: 2558
Subjects: สมรรถนะทางวัฒนธรรม, อาจารย์, นักศึกษา

description: 6, 23, วารสารวิทยาศาสตร์และเทคโนโลยี
An infrared study of galactic OH/IR stars. II. The `GLMP sample' of red oxygen-rich AGB stars
Creators: name: Jiménez-Esteban, F. M.
name: García-Lario, P.
name: Engels, D.
name: Calderón, J. V. Perea
Publisher: name: arXiv
Year: 2005
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We present optical and near-infrared finding charts taken from the DSS and 2MASS surveys of 94 IRAS sources selected from the GLMP catalogue (Garc\'ıa-Lario 1992), and accurate astrometry (~0.2") for most of them. Selection criteria were very red IRAS colours representative for OH/IR stars with optically thick circumstellar shells and the presence of variability according to the IRAS variability index (VAR>50). The main photometric properties of the stars in this `GLMP sample' are presented, discussed and compared with the correspondent properties of the `Arecibo sample' of OH/IR stars studied in Jiménez-Esteban et al. (2005a). We find that 37% of the sample (N=34) have no counterpart in the 2MASS, implying extremely high optical depths of their shells. Most of the sources identified in the 2MASS are faint (K>~8) and of very red colour in the near-infrared, as expected. The brightest 2MASS counterpart (K=5.3mag) was found for IRAS 18299--1705. Its blue colour H--K=1.3 suggests that IRAS 8299--1705 is a post-AGB star. A couple of GLMP sources have faint but relatively blue counterparts. They might be misidentifed field stars or stars hich experienced recently a drop of their mass loss rates. The `GLMP sample' in general is made of oxygen-rich AGB stars, which are highly obscured by their circumstellar shells. They belong to the same population as the reddest OH/IR stars in the `Arecibo sample'.
description: 15 pages, 9 figures, for associated finding charts see: http://www.hs.uni-hamburg.de/DE/Ins/Per/Jimenez-Esteban/Thesis/Atlas/glmp_ind ex.html accepted for publicating by A&A on 21/07/2005
ปัจจัยทำนายระดับการเฝ้าระวังและป้องกันภาวะเลือดออกในสมองของผู้ป่วยบาดเจ็บศีรษะเล็กน้อยโรงพยาบาลธรรมศาสตร์เฉลิมพระเกียรติ
Creators: name: บุบผา ลาภทวี
name: จิณพิชญ์ชา มะมม
Publisher: name: กองบริหารการวิจัย มหาวิทยาลัยธรรมศาสตร์
Year: 2558
Subjects: บาดเจ็บศีรษะเล็กน้อย, การเฝ้าระวัง, การป้องกัน, ภาวะเลือดออกในสมอง

description: 6, 23, วารสารวิทยาศาสตร์และเทคโนโลยี
The efficiency of electron acceleration in collisionless shocks and GRB energetics
Creators: name: Eichler, David
name: Waxman, Eli
Publisher: name: arXiv
Year: 2005
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: Afterglow observations are commonly used to determine the parameters of GRB explosions, the energy E, surrounding density n, post-shock magnetic field equipartition fraction ε_B and electron equipartition fraction ε_e, under the frequently made assumption that the efficiency of electron "injection" into relativistic shock acceleration is high, i.e. that the fraction f of electrons which undergo acceleration is f~1. We show that the value of f can not be determined by current observations, since currently testable model predictions for a parameter choice {E'=E/f,n'=n/f,ε'_B=fε_B,ε'_e=fε_e} are independent of the value of f for m_e/m_p< f< 1. Current observations imply that the efficiency f is similar for highly relativistic and for sub relativistic shocks, and plausibly suggest that f~1, quite unlike the situation in the Crab Nebula. However, values m_e/m_p< f<< 1 can not be ruled out, implying a factor m_e/m_p uncertainty in determination of model parameters. We show that early, <10 hr, radio afterglow observations, which will be far more accessible in the SWIFT era, may provide constraints on f. Such observations will therefore provide a powerful diagnostic of GRB explosions and of the physics of particle acceleration in collisionless shocks.
description: Accepted to ApJ; Improved and expanded discussion of observational signatures (sec. 3)
Multi-Scaling Differential Contraction Integral Method for Inverse Scattering Problems with Inhomogeneous Media
Creators: name: Zhong, Yu
name: Zardi, Francesco
name: Salucci, Marco
name: Oliveri, Giacomo
name: Massa, Andrea
Publisher: name: arXiv
Year: 2022
Subjects: subject: Signal Processing (eess.SP)
subject: Systems and Control (eess.SY)
subject: FOS: Electrical engineering, electronic engineering, information engineering

description: Practical applications of microwave imaging often require the solution of inverse scattering problems with inhomogeneous backgrounds. Towards this end, a novel inversion strategy, which combines the multi-scaling (MS) regularization scheme and the Difference Contraction Integral Equation (DCIE) formulation, is proposed. Such an integrated approach mitigates the non-linearity and the ill-posedness of the problem to obtain reliable high-resolution reconstructions of the unknown scattering profiles. The arising algorithmic implementation, denoted as MS-DCIE, does not require the computation of the Green's function of the inhomogeneous background, thus it provides an efficient and effective way to deal with complex scenarios. The performance of the MS-DCIE are assessed by means of numerical and experimental tests, in comparison with competitive state-of-the-art inversion strategies, as well.
"Inside Out" Growth Method for High-Quality Nitrogen-Doped Graphene
Creators: name: Fiori, Sara
name: Perilli, Daniele
name: Panighel, Mirco
name: Cepek, Cinzia
name: Ugolotti, Aldo
name: Sala, Alessandro
name: Liu, Hongsheng
name: Comelli, Giovanni
name: Di Valentin, Cristiana
name: Africh, Cristina
Publisher: name: arXiv
Year: 2020
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: High-quality nitrogen-doped graphene on nickel is prepared by exploiting both the catalytic properties of nickel and the solubility of nitrogen atoms into its bulk. Following the standard chemical vapor deposition procedure, a previously nitrogen-doped nickel substrate is exposed to carbon-containing precursors so that nitrogen atoms, segregating to the surface, remain trapped in the growing graphene network. Morphological and chemical characterization by scanning tunneling microscopy and X-ray photoelectron spectroscopy demonstrates that the process yields a flat, wide, continuous nitrogen-doped graphene layer. Experimental results are combined with a thorough density functional theory investigation of possible structural models, to obtain a clear description at the atomic scale of the various configurations of the nitrogen atoms observed in the graphene mesh. This growth method is potentially scalable and suitable for the production of high-performance nano-devices with well-defined nitrogen centers, to be exploited as metal-free carbon-based catalysts in several applicative fields such as electrochemistry, energy storage, gas storage/sensing or wastewater treatment.
description: 21 pages, including 4 figures, plus SI
การจัดการจราจรข้อมูลในโครงข่าย IP ด้วยวิธีจุดภายใน
Creators: name: ณัฐชามญฑ์ ศรีจำเริญรัตนา
name: ธนโชติ ธิติวิเชียรเลิศ
name: ณัฐดนัย สุขแสง
name: กายรัฐ เจริญราษฎร์
Publisher: name: กองบริหารการวิจัย มหาวิทยาลัยธรรมศาสตร์
Year: 2558
Subjects: วิธีจุดภายใน, การจัดการจราจรข้อมูล, โครงข่ายไอพี

description: 6, 23, วารสารวิทยาศาสตร์และเทคโนโลยี
Superconducting decay length in a ferromagnetic metal
Creators: name: Gusakova, D. Yu.
name: Golubov, A. A.
name: Kupriyanov, M. Yu.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: The complex decay length xi characterizing penetration of superconducting correlations into a ferromagnet due to the proximity effect is studied theoretically in the frame of the linearized Eilenberger equations. The real part xi_1 and imaginary part xi_2 of the decay length are calculated as functions of exchange energy and the rates of ordinary, spin flip and spin orbit electronic scattering in a ferromagnet. The lengths xi_1,2 determine the spatial scales of, respectively, decay and oscillation of a critical current in SFS Josephson junctions in the limit of large distance between superconducting electrodes. The developed theory provides the criteria of applicability of the expressions for xi_1 and xi_2 in the dirty and the clean limits which are commonly used in the analysis of SF hybrid structures.
description: 5 pages, 3 figures
A detailed study of the rotating toroids in G31.41+0.31 and G24.78+0.08
Creators: name: Beltran, Maria T.
name: Cesaroni, Riccardo
name: Neri, Roberto
name: Codella, Claudio
name: Furuya, Ray S.
name: Testi, Leonardo
name: Olmi, Luca
Publisher: name: arXiv
Year: 2005
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We present the results of high angular resolution millimeter observations of gas and dust toward G31.41+0.31 and G24.78+0.08, two high-mass star forming regions where four rotating massive toroids have been previously detected by Beltran et al. (2004). The CH3CN (12-11) emission of the toroids in G31.41+0.31 and core A1 in G24.78+0.08 has been modeled assuming that it arises from a disk-like structure seen edge-on, with a radial velocity field. For G31.41+0.31 the model properly fits the data for a velocity v_rot~1.7 km/s at the outer radius R_out~13400 AU and an inner radius R_inn~1340 AU, while for core A1 in G24.78+0.08 the best fit is obtained for v_rot~2.0 km/s at R_out~7700 AU and R_inn~2300 AU. Unlike the rotating disks detected around less luminous stars, these toroids are not undergoing Keplerian rotation. From the modeling itself, however, it is not possible to distinguish between constant rotation or constant angular velocity, since both velocity fields suitably fit the data. The best fit models have been computed adopting a temperature gradient of the type T proportional R^{-3/4}, with a temperature at the outer radius T_out~100 K for both cores. The M_dyn needed for equilibrium derived from the models is much smaller than the mass of the cores, suggesting that such toroids are unstable and undergoing gravitational collapse. The collapse is also supported by the CH3^{13}CN or CH3CN line width measured in the cores, which increases toward the center of the toroids. The estimates of v_inf and \dot M_acc are ~2 km/s and 3x10^{-2} M_sun/yr for G31.41+0.31, and ~1.2 km/s and ~9x10^{-3} M_sun/yr for G24.78+0.08 A1. Such large accretion rates could weaken the effect of stellar winds and radiation pressure and allow further accretion on the star.
description: 27 pages, including 25 figures, 12 tables;accepted for publication by A&A
Fault-tolerant Post-Selection for Low Overhead Magic State Preparation
Creators: name: Bombín, Héctor
name: Pant, Mihir
name: Roberts, Sam
name: Seetharam, Karthik I.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We introduce a framework for fault-tolerant post-selection (FTPS) of fault-tolerant codes and channels -- such as those based on surface-codes -- using soft-information metrics based on visible syndrome and erasure information. We introduce several metrics for ranking configurations of syndromes and erasures. In particular, we introduce the \emph{logical gap} (and variants thereof) as a powerful soft-information metric for predicting logical error rates of fault-tolerant channels based on topological error-correcting codes. The logical gap is roughly the unsigned weight difference between inequivalent logical corrections and is adaptable to any tailored noise model or decoder. We deploy this framework to prepare high-quality surface code magic states with low overhead under a model of independent and identically distributed (\emph{i.i.d.}) Pauli and erasure errors. Post-selection strategies based on the logical gap can suppress the encoding error rate of a magic state preparation channel to the level of the physical error rate with low overhead. For example, when operating at $60\%$ the bulk threshold of the corresponding surface code, an overall reduction of the encoding error rate by a factor of $15$ is achievable with a relative overhead factor of ${< 2}$ (approximately $23$ times less than that of simple syndrome-counting rules). We analyze a schematic buffer architecture for implementing post-selection rules on magic state factories in the context of magic state distillation. The FTPS framework can be utilized for mitigating errors in more general fault-tolerant logical channels.
description: 10+7 pages, 13 figures, comments welcome
Nets with Mana: A Framework for Chemical Reaction Modelling
Creators: name: Genovese, Fabrizio Romano
name: Loregian, Fosco
name: Palombi, Daniele
Publisher: name: arXiv
Year: 2021
Subjects: subject: Category Theory (math.CT)
subject: Formal Languages and Automata Theory (cs.FL)
subject: Molecular Networks (q-bio.MN)
subject: FOS: Mathematics
subject: FOS: Computer and information sciences
subject: FOS: Biological sciences

description: We use categorical methods to define a new flavor of Petri nets where transitions can only fire a limited number of times, specified by a quantity that we call mana. We do so with chemistry in mind, looking at ways of modelling the behavior of chemical reactions that depend on enzymes to work. We prove that such nets can be either obtained as a result of a comonadic construction, or by enriching them with extra information encoded into a functor. We then use a well-established categorical result to prove that the two constructions are equivalent, and generalize them to the case where the firing of some transitions can "regenerate" the mana of others. This allows us to represent the action of catalysts and also of biochemical processes where the byproducts of some chemical reaction are exactly the enzymes that another reaction needs to work.
description: 15 pages
Inferring Quantum Network Topology using Local Measurements
Creators: name: Chen, Daniel T.
name: Doolittle, Brian
name: Larson, Jeffrey M.
name: Saleem, Zain H.
name: Chitambar, Eric
Publisher: name: arXiv
Year: 2022
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Statistical correlations that can be generated across the nodes in a quantum network depend crucially on its topology. However, this topological information might not be known a priori, or it may need to be verified. In this paper, we propose an efficient protocol for distinguishing and inferring the topology of a quantum network. We leverage entropic quantities -- namely, the von Neumann entropy and the measured mutual information -- as well as measurement covariance to uniquely characterize the topology. We show that the entropic quantities are sufficient to distinguish two networks that prepare GHZ states. Moreover, if qubit measurements are available, both entropic quantities and covariance can be used to infer the network topology without state-preparation assumptions. We show that the protocol can be entirely robust to noise and can be implemented via quantum variational optimization. Numerical experiments on both classical simulators and quantum hardware show that covariance is generally more reliable for accurately and efficiently inferring the topology, whereas entropy-based methods are often better at identifying the absence of entanglement in the low-shot regime.
Non-equilibrium effects on electron-phonon coupling constant in metals
Creators: name: Miao, Wuli
name: Wang, Moran
Publisher: name: arXiv
Year: 2020
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: Understanding of the energy exchange between electrons and phonons in metals is important for micro- and nano-manufacturing and system design. The electron-phonon (e-ph) coupling constant is to describe such exchange strength, yet its variation remains still unclear at micro- and nanoscale where the non-equilibrium effects are significant. In this work, an e-ph coupling model is proposed by transforming the full scattering terms into relaxation time approximation forms in the coupled electron and phonon Boltzmann transport equations. Consequently, the non-equilibrium effects are included in the calculation of e-ph coupling constant. The coupling model is verified by modeling the ultrafast dynamics in femtosecond pump-probe experiments on metal surface, which shows consistent results with the full integral treatment of scattering terms. The e-ph coupling constant is strongly reduced due to both the temporal non-equilibrium between different phonon branches and the spatial non-equilibrium of electrons in confined space. The present work will promote not only a fundamental understanding of the e-ph coupling constant but also the theoretical description of coupled electron and phonon transport at micro- and nanoscale.
Tracing the first stars with cosmic infrared background fluctuations
Creators: name: Kashlinsky, A.
name: Arendt, R. G.
name: Mather, J.
name: Moseley, S. H.
Publisher: name: arXiv
Year: 2005
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: The deepest space and ground-based observations find metal-enriched galaxies at cosmic times when the Universe was <1 Gyr old. These stellar populations had to be preceded by the metal-free first stars, Population III. Recent cosmic microwave background polarization measurements indicate that stars started forming early when the Universe was $\lsim200$ Myr old. Theoretically it is now thought that Population III stars were significantly more massive than the present metal-rich stellar populations. While such sources will not be individually detectable by existing or planned telescopes, they would have produced significant cosmic infrared background radiation in the near- infrared, whose fluctuations reflect the conditions in the primordial density field. Here we report a measurement of diffuse flux fluctuations after removing foreground stars and galaxies. The anisotropies exceed the instrument noise and the more local foregrounds and can be attributed to emission from massive Population III stars, providing observational evidence of an era dominated by these objects.
description: appears as Article in Nature, 3 Nov 2005. Maps and paper with high-resolution figures can be oibtained from http://haiti.gsfc.nasa.gov/kashlinsky/LIBRA/NATURE
Topological organization, functional characterization and localization of the bovine rod photoreceptor na/ca-k exchanger
Creators: name: Kim, Tom Sang-Yong
Publisher: name: University of British Columbia
Year: 2009

description: The Na/Ca-K exchanger in vertebrate photoreceptors plays an essential role in regulating the calcium concentration in photoreceptor outer segments. The structural and functional properties of the bovine rod photoreceptor Na/Ca-K exchanger were examined in this study using eight, anti-exchanger monoclonal antibodies. Experimental evidence for the topological organization of the exchanger was provided by mapping the epitopes of the antibodies using glutathione S-transferase fusion proteins containing specific regions of the exchanger. Five antibodies were mapped to the large N-terminal hydrophilic domain and shown to label the extracellular surface of the rod outer segment (ROS) plasma membrane by immunogold labeling for electron microscopy. Three antibodies were mapped to the hydrophilic domain connecting the two putative transmembrane domains and shown to label the cytoplasmic surface. The antibodies were also used to determine subcellular localization of the exchanger and to purify the exchanger by immunoaffinity chromatography. The exchanger was localized to the plasma membrane of rod photoreceptor outer segments. When the ROS membrane proteins were solubilized in CHAPS detergent, the exchanger did not appear to co-purify with other ROS membrane proteins. Treatment of the immunoaffinity-purified exchanger with deglycosylating enzymes indicated that the exchanger possesses a large amount of O-linked oligosaccharides in the large N-terminal hydrophilic domain. Limited proteolysis was used to determine the importance of the large extracellular and intracellular domains for ion transport. Trypsin degraded the extracellular domain, and kallikrein degraded a large part of the cytoplasmic domain. Following the removal of either of these hydrophilic domains, the exchanger exhibited Na⁺ and K⁺-dependent Ca²⁺ efflux activity similar to that of the untreated exchanger. The Vmax for the protease treated exchangers, however, increased ~2 fold. These results indicate that the ion binding and transport sites are located within or near the transmembrane domains and the removal of the bulky hydrophilic domain enables the exchanger to undergo a faster conformational change during ion transport. The oligomeric nature of the exchanger was determined using velocity sedimentation and size exclusion chromatography. Hydrodynamic properties of the detergent solubilized exchanger suggested that the exchanger is a monomer. Chemical crosslinking and velocity sedimentation studies, however, indicated that the exchanger exists as a dimer within the plasma membrane. These studies provide insight into the structural and functional properties of the exchanger. The O-glycosylated exchanger is exclusively localized in the ROS plasma membrane as a dimer, and the large hydrophilic domains of the exchanger do not appear to play a role in ion transport.
Certain residual properties of generalized Baumslag-Solitar groups
Creators: name: Sokolov, E. V.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Group Theory (math.GR)
subject: FOS: Mathematics
subject: 20E26, 20E08 (Primary) 20E06 (Secondary)

description: Let $G$ be a generalized Baumslag-Solitar group and $\mathcal{C}$ be a class of groups containing at least one non-unit group and closed under taking subgroups, extensions, and Cartesian products of the form $\prod_{y \in Y}X_{y}$, where $X, Y \in \mathcal{C}$ and $X_{y}$ is an isomorphic copy of $X$ for every $y \in Y$. We give a criterion for $G$ to be residually a $\mathcal{C}$-group provided $\mathcal{C}$ consists only of periodic groups. We also prove that $G$ is residually a torsion-free $\mathcal{C}$-group if $\mathcal{C}$ contains at least one non-periodic group and is closed under taking homomorphic images. These statements generalize and strengthen some known results. Using the first of them, we provide criteria for a GBS-group to be a) residually nilpotent; b) residually torsion-free nilpotent; c) residually free.
description: 19 pages, in English
Modified Gauge Invariant Einstein Maxwell Gravity and Stability of Spherical perfect fluid Stars with Magnetic Monopoles
Creators: name: Ghaffarnejad, Hossein
name: Naderi, Leyla
Publisher: name: arXiv
Year: 2022
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: As an alternative gravity model we consider an extended Einstein-Maxwell gravity containing a gauge invariance property. Extension is assumed to be addition of a directional coupling between spatial electromagnetic fields with the Ricci tensor. We will see importance of the additional term in making a compact stellar object and value of its radius. As an application of this model we substitute ansatz of magnetic field of a hypothetical magnetic monopole which has just time independent radial component and for matter part we assume a perfect fluid stress tensor. To obtain spherically symmetric internal metric of the perfect fluid stellar compact object we solve Tolman-Oppenheimer-Volkoff equation with a polytropic form of equation of state as $p(ρ)=aρ^2$. Using dynamical system approach we study stability of the solutions for which arrow diagrams show saddle (quasi stable) for $a<0$ (dark stars) and sink (stable) for $a>0$ (normal visible stars). We check also the energy conditions, speed of sound and Harrison-Zeldovich-Novikov static stability criterion for obtained solution and confirm that they make stable state.
description: 26 pages, 4 figures, presented as virtual in the 7th Gravity and Particles Meeting of Northeast Iran, 14-15 Desember 2022, Shahrood University of Technology https://www.hsu.ac.ir/wp-content/uploads/2022/12/poster_221206_195327-1.jpg
2D correlations in the van der Waals ferromagnet CrBr$_{3}$ using high frequency electron spin resonance spectroscopy
Creators: name: Saiz, C. L.
name: Delgado, J. A.
name: van Tol, J.
name: Tartaglia, T.
name: Tafti, F.
name: Singamaneni, S. R.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Broadening the knowledge and understanding on the magnetic correlations in van der Waals layered magnets is critical in realizing their potential next-generation applications. In this study, we employ high frequency (240 GHz) electron spin resonance (ESR) spectroscopy on plate-like CrBr$_{3}$ to gain insight into the magnetic interactions as a function of temperature (200 - 4 K) and the angle of rotation $θ$. We find that the temperature dependence of the ESR linewidth is well described by the Ginzberg-Landau critical model as well as Berezinskii-Kosterlitz-Thouless (BKT) transition model, indicative of the presence of two-dimensional (2D) correlations. This suggests that the three-dimensional ferromagnet CrBr$_{3}$, which has been described as an Ising or Heisenberg ferromagnet, could present 2D magnetic correlations and BKT-like behavior even in its bulk form; an observation that, to the best of our knowledge, has not been reported in the literature. Furthermore, our findings show that the resonance field follows a $(3cos^2θ - 1)$-like angular dependence, while the linewidth follows a $(3cos^2θ - 1)^2$-like angular dependence. This observed angular dependence of the resonance field and linewidth further confirm an unanticipated 2D magnetic behavior in CrBr$_{3}$. This behavior is likely due to the interaction of the external magnetic field applied during the ESR experiment that allows for the mediation of long-range vortex-like correlations between the spin clusters that may have formed due to magnetic phase separation. This study demonstrates the significance of employing spin sensitive techniques such as ESR to better understand the magnetic correlations in similar van der Waals magnets.
description: 6 pages, 5 figures, 1 table
Structure-Dependent QED Effects in Exclusive B Decays at Subleading Power
Creators: name: Cornella, Claudia
name: König, Matthias
name: Neubert, Matthias
Publisher: name: arXiv
Year: 2022
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: We derive a factorization theorem for the structure-dependent QED effects in the weak exclusive process $B^-\to\ell^-\barν_\ell$, i.e., effects probing the internal structure of the $B$ meson. The derivation requires a careful treatment of endpoint-divergent convolutions common to subleading-power factorization formulas. We find that the decay amplitude is sensitive to two- and three-particle light-cone distribution amplitudes of the $B$ meson as well as to a new hadronic parameter $F(μ,Λ)$, which generalizes the notion of the $B$-meson decay constant in the presence of QED effects. This is the first derivation of a subleading-power factorization theorem in which the soft functions are non-perturbative hadronic matrix elements.
description: 5 pages, 2 figures, v2: inclusion of soft-collinear modes in the factorization theorem, explicit expression for IR poles in the virtual amplitude given, references added, main conclusions unchanged, v3: clarifications added, definition of hadronic parameter F adjusted, matches journal version
Simulation of short pulse photoemission in a micro-diode with implications for optimal beam brightness
Creators: name: Árnason, Hákon Örn
name: Torfason, Kristinn
name: Manolescu, Andrei
name: Valfells, Ágúst
Publisher: name: arXiv
Year: 2023
Subjects: subject: Plasma Physics (physics.plasm-ph)
subject: Accelerator Physics (physics.acc-ph)
subject: FOS: Physical sciences

description: Molecular dynamics simulations, with full Coulomb interaction are used to model short-pulse photoemission from a finite area in a microdiode. We demonstrate three emission regimes, source-limited emission, space-charge limited emission for short-pulses, and space-charge limited emission for the steady state. We show that beam brightness is at a maximum during transition from the source-limited emission regime to the space-charge limited emission regime for short pulses. From our simulations it is apparent that the important factor is the emitter spot size when estimating the critical charge density for short-pulse electron emission.
description: 9 pages 10 figures
Quantum entanglement, local indicators and effect of external fields in the Kugel-Khomskii model
Creators: name: Valiulin, V. E.
name: Mikheyenkov, A. V.
name: Chtchelkatchev, N. M.
name: Kugel, K. I.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Using the exact diagonalization technique, we determine the energy spectrum and wave functions for finite chains described by the two-spin (Kugel--Khomskii) model with different types of intersubsystem exchange terms. The found solutions provide a possibility to address the problem of quantum entanglement inherent to this class of models. We put the main emphasis on the calculations of the concurrence treated as an adequate numerical measure of the entanglement. We also analyze the behavior of two-site correlation functions considered as a local indicator of entanglement. We construct the phase diagrams of the models involving the regions of nonzero entanglement. The pronounced effect of external fields, conjugated to both spin variables on the regions with entanglement, could both enhance and weaken the entanglement depending on the parameters of the models.
Chiral phonons probed by X rays
Creators: name: Ueda, Hiroki
name: García-Fernández, Mirian
name: Agrestini, Stefano
name: Romao, Carl P.
name: Brink, Jeroen van den
name: Spaldin, Nicola A.
name: Zhou, Ke-Jin
name: Staub, Urs
Publisher: name: arXiv
Year: 2023
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: The concept of chirality is of great relevance in nature, from chiral molecules such as sugar to parity transformations in particle physics. In condensed matter physics, recent studies have demonstrated chiral fermions and their relevance in emergent phenomena closely related to topology. The experimental verification of chiral phonons (bosons) remains challenging, however, despite their expected strong impact on fundamental physical properties. Here we show experimental proof of chiral phonons using resonant inelastic X-ray scattering with circularly polarized X rays. Using the prototypical chiral material, quartz, we demonstrate that circularly polarized X rays, which are intrinsically chiral, couple to chiral phonons at specific positions in reciprocal space, allowing us to determine the chiral dispersion of the lattice modes. Our experimental proof of chiral phonons demonstrates a new degree of freedom in condensed matter that is both of fundamental importance and opens the door to exploration of novel emergent phenomena based on chiral bosons
description: 5
Bandgap evolution in nanographene assemblies
Creators: name: de Lima, F. Crasto
name: Fazzio, A.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Recently cycloarene has been experimentally obtained in a self-assembled structure, forming graphene-like monoatomic layered systems. Here, we establish the bandgap engineering/prediction in cycloarene assemblies within a combination of density functional theory and tight-binding Hamiltonians. Our results show a weak dependence of the gap with the assembly geometry, contrasting a strong dependence with the inter-molecule bond density. We derived a effective model that allows the interpretation of the arising energy gap for general particle-hole symmetric molecular arranges based on inter-molecular bond strength.
Die Bundesordnung des einen Haushalts des Lebens als ökologisches Programm der Ökumene
Creators: name: Werner, Dietrich
Publisher: name: Ökumenische Rundschau
Year: 2025

description: Ökumenische Rundschau, Bd. 40 Nr. 3 (1991): Ökumenische Rundschau, Band 40, Heft 3
Strong decays of $T_{c\bar s0}(2900)^{++/0}$ as a fully open-flavor tetraquark state
Creators: name: Lian, Ding-Kun
name: Chen, Wei
name: Chen, Hua-Xing
name: Dai, Ling-Yun
name: Steele, T. G.
Publisher: name: arXiv
Year: 2023
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Experiment (hep-ex)
subject: FOS: Physical sciences

description: We have studied the strong decay properties of the recently observed $T^a_{c\bar s0}(2900)^{++/0}$ by considering it as a $cu\bar{d}\bar{s}/cd\bar{u}\bar{s}$ fully open-flavor tetraquark state with $I(J^P)=1(0^+)$. In the framework of QCD sum rules, we have calculated the three-point correlation functions of the two-body strong decay processes $T^a_{c\bar s0}(2900)^{++}\rightarrow D_s^+π^+$, $D^+K^+, D_s^{\ast +}ρ^+$ and $D_{s1}^+π^+$. The full width of $T^a_{c\bar s0}(2900)^{++/0}$ is obtained as $161.7\pm94.8$ MeV, which is consistent with the experimental observation. We predict the relative branching ratios as $Γ(T\rightarrow D_sπ):Γ(T\rightarrow DK):Γ(T\rightarrow D_s^{\ast} ρ):Γ(T\rightarrow D_{s1}π)\approx1.00:1.10:0.04:0.43$, implying that the main decay modes of $T^a_{c\bar s0}(2900)^{++/0}$ state are $D_sπ$ and $DK$ channels in our calculations. However, the $P$-wave decay mode $D_{s1}π$ is also comparable and important by including the uncertainties. To further identify the nature of $T^a_{c\bar s0}(2900)^{++/0}$, we suggest confirming them in the $DK$ and $D_{s}π$ final states, and measuring the above ratios in future experiments.
description: 9 pages, 7 figures
Identifying safe intersection design through unsupervised feature extraction from satellite imagery
Creators: name: Wijnands, Jasper S.
name: Zhao, Haifeng
name: Nice, Kerry A.
name: Thompson, Jason
name: Scully, Katherine
name: Guo, Jingqiu
name: Stevenson, Mark
Publisher: name: arXiv
Year: 2020
Subjects: subject: Computer Vision and Pattern Recognition (cs.CV)
subject: Machine Learning (cs.LG)
subject: Multimedia (cs.MM)
subject: Image and Video Processing (eess.IV)
subject: FOS: Computer and information sciences
subject: FOS: Electrical engineering, electronic engineering, information engineering
subject: I.2.10; I.4.6; I.4.8; I.4.9; I.5.3; J.2; J.6
subject: 68T45 (Primary) 68U07, 68U10 (Secondary)

description: The World Health Organization has listed the design of safer intersections as a key intervention to reduce global road trauma. This article presents the first study to systematically analyze the design of all intersections in a large country, based on aerial imagery and deep learning. Approximately 900,000 satellite images were downloaded for all intersections in Australia and customized computer vision techniques emphasized the road infrastructure. A deep autoencoder extracted high-level features, including the intersection's type, size, shape, lane markings, and complexity, which were used to cluster similar designs. An Australian telematics data set linked infrastructure design to driving behaviors captured during 66 million kilometers of driving. This showed more frequent hard acceleration events (per vehicle) at four- than three-way intersections, relatively low hard deceleration frequencies at T-intersections, and consistently low average speeds on roundabouts. Overall, domain-specific feature extraction enabled the identification of infrastructure improvements that could result in safer driving behaviors, potentially reducing road trauma.
description: 16 pages, 10 figures. Computer-Aided Civil and Infrastructure Engineering (2020)
Quantum dots in Si/SiGe 2DEGs with Schottky top-gated leads
Creators: name: Slinker, K A
name: Lewis, K L M
name: Haselby, C C
name: Goswami, S
name: Klein, L J
name: Chu, J O
name: Coppersmith, S N
name: Joynt, Robert
name: Blick, R H
name: Friesen, Mark
name: Eriksson, M A
Publisher: name: arXiv
Year: 2005
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: We report on the fabrication and characterization of quantum dot devices in a Schottky-gated silicon/silicon-germanium two-dimensional electron gas (2DEG). The dots are confined laterally inside an etch-defined channel, while their potential is modulated by an etch-defined 2DEG gate in the plane of the dot. For the first time in this material, Schottky top gates are used to define and tune the tunnel barriers of the dot. The leakage current from the gates is reduced by minimizing their active area. Further suppression of the leakage is achieved by increasing the etch depth of the channel. The top gates are used to put the dot into the Coulomb blockade regime, and conductance oscillations are observed as the voltage on the side gate is varied.
description: New Fig. 1, submitted to New Journal of Physics