cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Bridging ultra-high-Q devices and photonic circuits
Creators: name: Yang, Ki Youl
name: Oh, Dong Yoon
name: Lee, Seung Hoon
name: Yang, Qi-Fan
name: Yi, Xu
name: Vahala, Kerry
Publisher: name: arXiv
Year: 2017
Subjects: subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: Optical microcavities are essential in numerous technologies and scientific disciplines. However, their application in many areas relies exclusively upon discrete microcavities in order to satisfy challenging combinations of ultra-low-loss performance (high cavity-Q-factor) and cavity design requirements. Indeed, finding a microfabrication bridge connecting ultra-high-Q device functions with micro and nanophotonic circuits has been a long-term priority of the microcavity field. Here, an integrated ridge resonator having a record Q factor over 200 million is presented. Its ultra-low-loss and flexible cavity design brings performance that has been the exclusive domain of discrete silica and crytalline microcavity devices to integrated systems. Two distinctly different devices are demonstrated: soliton sources with electronic repetition rates and high-coherence Brillouin lasers. This multi-device capability and performance from a single integrated cavity platform represents a critical advance for future nanophotonic circuits and systems.
description: (1) Added Fig.4 to show high-coherence Brillouin lasing using the integrated resonator; (2) Added system illustrations (Fig. 1a); (3) Changed title of paper to reflect demonstrations of both low-repetition-rate soliton mode locking and Brillouin laser using the integrated resonator; (4) Fig. 6 added in Methods to describe resonator-to-waveguide phase-matching control; (5) Other minor changes
On cointegration and cryptocurrency dynamics
Creators: name: Keilbar, Georg
name: Zhang, Yanfen
Publisher: name: Humboldt-Universität zu Berlin
Year: 2021
Subjects: subject: Cointegration
subject: VECM
subject: Nonstationarity
subject: Cryptocurrencies
subject: 330 Wirtschaft

description: This paper aims to model the joint dynamics of cryptocurrencies in a nonstationary setting. In particular, we analyze the role of cointegration relationships within a large system of cryptocurrencies in a vector error correction model (VECM) framework. To enable analysis in a dynamic setting, we propose the COINtensity VECM, a nonlinear VECM specification accounting for a varying systemwide cointegration exposure. Our results show that cryptocurrencies are indeed cointegrated with a cointegration rank of four. We also find that all currencies are affected by these long term equilibrium relations. The nonlinearity in the error adjustment turned out to be stronger during the height of the cryptocurrency bubble. A simple statistical arbitrage trading strategy is proposed showing a great in-sample performance, whereas an out-of-sample analysis gives reason to treat the strategy with caution.
Rationalizing systematic discrepancies between election outcomes and opinion polls
Creators: name: Gamberi, Luca
name: Vivo, Pierpaolo
name: Förster, Yanik-Pascal
name: Tzanis, Evan
name: Annibale, Alessia
Publisher: name: arXiv
Year: 2022
Subjects: subject: Physics and Society (physics.soc-ph)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: The Bradley effect concerns the discrepancy between opinion polls and actual election outcomes that emerges when candidates do not exhibit ideological, sexual or racial mainstream features. This effect was first observed during the 1982 election for the Governor of California that resulted in a significant loss for the black Democratic candidate, Tom Bradley, despite him being ahead in polls. It has been argued that poll respondents may tend to mask their true political preference in favour of what is generally considered more socially acceptable. We propose an exactly solvable statistical mechanical model, which allows for a quantitative exploration of this phenomenon. The model includes three main ingredients: (i) the tendency of individuals to align their real preference to the declared (public) opinions of others, (ii) a term accounting for an individual integrity factor, which induces voters to be consistent between their public and private opinions, and (iii) a self-monitoring component, which tunes the strength by which an individual is affected by and wishes to publicly conform to social norms. We observe the emergence of order in a wide range of parameters of the model and discuss the effect of noise on the correlation between hidden and public preference. Finally, we present an application of this model to the prediction of election outcomes.
description: 16 pages, 9 figures
Echo-enhanced molecular orientation at high temperatures
Creators: name: Tutunnikov, Ilia
name: Xu, Long
name: Prior, Yehiam
name: Averbukh, Ilya Sh.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Chemical Physics (physics.chem-ph)
subject: Optics (physics.optics)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Ultrashort laser pulses are widely used for transient field-free molecular orientation -- a phenomenon important in chemical reaction dynamics, ultrafast molecular imaging, high harmonics generation, and attosecond science. However, significant molecular orientation usually requires rotationally cold molecules, like in rarified molecular beams, because chaotic thermal motion is detrimental to the orientation process. Here we propose to use the mechanism of the echo phenomenon previously observed in hadron accelerators, free-electron lasers, and laser-excited molecules to overcome the destructive thermal effects and achieve efficient field-free molecular orientation at high temperatures. In our scheme, a linearly polarized short laser pulse transforms a broad thermal distribution in the molecular rotational phase space into many separated narrow filaments due to the nonlinear phase mixing during the post-pulse free evolution. Molecular subgroups belonging to individual filaments have much-reduced dispersion of angular velocities. They are rotationally cold, and a subsequent moderate terahertz (THz) pulse can easily orient them. The overall enhanced orientation of the molecular gas is achieved with some delay, in the course of the echo process combining the contributions of different filaments. Our results demonstrate that the echo-enhanced orientation is an order of magnitude higher than that of the THz pulse alone. The mechanism is robust -- it applies to different types of molecules, and the degree of orientation is relatively insensitive to the temperature. The laser and THz pulses used in the scheme are readily available, allowing quick experimental demonstration and testing in various applications. Breaking the phase space to individual filaments to overcome hindering thermal conditions may find a wide range of applications beyond molecular orientation.
description: 12 pages, 10 figures
Compatibilities and Challenges of Crisis Management in China— An Empirical Study of Shanghai Lockdown
Creators: name: Shi, Haotong
Publisher: name: University of Chicago
Year: 2022
Subjects: subject: Crisis management
subject: zero-COVID strategy
subject: Centralized institutional structure
subject: Community-level institutional system

description: As the most severe public health crisis in recent decades, the aftermath of the COVID-19 pandemic negatively impacted worldwide. Crisis management strategies in response to this epidemic vary from country to country. China, pursuing the zero-COVID policy during this crisis, caused constantly debated. Prior studies have focused on the justification of the zero-COVID strategy and its political implication in China. Yet, limited attention has been given to examining the function of Chinese institutional features in implementing the policy. This article bridged the gap by recapitulating the framework of China's institutional system and analyzing its compatibility in pursuing the zero-COVID strategy, using the 2022 Shanghai lockdown as the case study. While answering the question of what might be advantages of China in implementing the virus elimination approach during the pandemic, this research concludes that China's centralized and hierarchical institutional structure enhances the effectiveness and swiftness of policy enactment and consolidated mobilization during the Shanghai lockdown. In addition, China's highly pervasive community-level institutional system facilitates effective communication between the government and the public, as well as helps practice the regulation in achieving the zero-COVID goal under the Shanghai case. Besides the structural analysis, this research also demonstrates potential difficulties and complications that the virus elimination principles might face in China. Through reviewing the characteristics of the current prevalent Omicron variant, the results showed that its rapid spreading speed, concealing property, and more extended activity on inanimate objects would be factors that challenge the patience and resolution of the public in reacting to the zero-COVID policy. These findings provide a more dynamic perspective to further crisis management research.
A seven-planet resonant chain in TRAPPIST-1
Creators: name: Luger, Rodrigo
name: Sestovic, Marko
name: Kruse, Ethan
name: Grimm, Simon L.
name: Demory, Brice-Olivier
name: Agol, Eric
name: Bolmont, Emeline
name: Fabrycky, Daniel
name: Fernandes, Catarina S.
name: Van Grootel, Valérie
name: Burgasser, Adam
name: Gillon, Michaël
name: Ingalls, James G.
name: Jehin, Emmanuël
name: Raymond, Sean N.
name: Selsis, Franck
name: Triaud, Amaury H. M. J.
name: Barclay, Thomas
name: Barentsen, Geert
name: Howell, Steve B.
name: Delrez, Laetitia
name: de Wit, Julien
name: Foreman-Mackey, Daniel
name: Holdsworth, Daniel L.
name: Leconte, Jérémy
name: Lederer, Susan
name: Turbet, Martin
name: Almleaky, Yaseen
name: Benkhaldoun, Zouhair
name: Magain, Pierre
name: Morris, Brett
name: Heng, Kevin
name: Queloz, Didier
Publisher: name: arXiv
Year: 2017
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: The TRAPPIST-1 system is the first transiting planet system found orbiting an ultra-cool dwarf star. At least seven planets similar to Earth in radius and in mass were previously found to transit this host star. Subsequently, TRAPPIST-1 was observed as part of the K2 mission and, with these new data, we report the measurement of an 18.77 d orbital period for the outermost planet, TRAPPIST-1h, which was unconstrained until now. This value matches our theoretical expectations based on Laplace relations and places TRAPPIST-1h as the seventh member of a complex chain, with three-body resonances linking every member. We find that TRAPPIST-1h has a radius of 0.727 Earth radii and an equilibrium temperature of 173 K. We have also measured the rotational period of the star at 3.3 d and detected a number of flares consistent with a low-activity, middle-aged, late M dwarf.
description: 42 pages, 8 figures, 2 tables
Degree $3$ relative invariant for unitary involutions
Creators: name: Barry, Demba
name: Masquelein, Alexandre
name: Quéguiner-Mathieu, Anne
Publisher: name: arXiv
Year: 2022
Subjects: subject: Rings and Algebras (math.RA)
subject: FOS: Mathematics
subject: 11E72 11E81 16K20 16W10

description: Using the Rost invariant for non split simply connected groups, we define a relative degree $3$ cohomological invariant for pairs of orthogonal or unitary involutions having isomorphic Clifford or discriminant algebras. The main purpose of this paper is to study general properties of this invariant in the unitary case, that is for torsors under groups of outer type ${\sf A}$. If the underlying algebra is split, it can be reinterpreted in terms of the Arason invariant of quadratic forms, using the trace form of a hermitian form. When the algebra with unitary involution has a symplectic or orthogonal descent, or a symplectic or orthogonal quadratic extension, we provide comparison theorems between the corresponding invariants of unitary and orthogonal or symplectic types. We also prove the relative invariant is classifying in degree $4$, at least up to conjugation by the non-trivial automorphism of the underlying quadratic extension. In general, choosing a particular base point, the relative invariant also produces absolute Arason invariants, under some additional condition on the underlying algebra. Notably, if the algebra has even co-index, so that it admits a hyperbolic involution, which is unique up to isomorphism, we get a so-called {\em hyperbolic} Arason invariant. Assuming in addition the algebra has degree $8$, we may also define a {\em decomposable} Arason invariant. It generally does not coincide with the hyperbolic Arason invariant, as the hyperbolic involution need not be totally decomposable.
description: 39 pages
Performance of quantum batteries with correlated and uncorrelated chargers
Creators: name: Arjmandi, Mohammad B.
name: Shokri, Abbas
name: Faizi, Esfandyar
name: Mohammadi, Hamidreza
Publisher: name: arXiv
Year: 2022
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Energy can be stored in quantum batteries by electromagnetic fields as chargers. In this paper, the performance of a quantum battery with single and double chargers is studied. It is shown that by using two independent charging fields, prepared in coherent states, charging power of the quantum battery can be significantly improved, though the average number of embedded photons are kept the same in both scenarios. Then the results reveal that for the case of initially correlated states of the chargers the amount of extractable energy, measured by ergotropy, is more than initially uncorrelated ones, with appropriate degrees of field's intensities. Though the correlated chargers lead to greater reduction in purity of quantum battery, more energy and in turn, more ergotropy is stored in this case. In addition, we study the battery-charger mutual information and Von Neumann entropy and by using their relation, we find that both quantum and classical correlations are generated between the quantum battery and chargers. Then we study quantum consonance of the battery as the non-local coherence among it's cells and find some qualitative relations between the generation of such correlations and the capability of energy storage in the quantum battery.
description: 9 pages and 14 figures
A Scintillation Arc Survey of 22 Pulsars with Low to Moderate Dispersion Measures
Creators: name: Stinebring, Dan R.
name: Rickett, Barney J.
name: Minter, Anthony H.
name: Hill, Alex S.
name: Jussila, Adam P.
name: Mathis, Lele
name: McLaughlin, Maura A.
name: Ocker, Stella Koch
name: Ransom, Scott M.
Publisher: name: arXiv
Year: 2022
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: Context: By providing information about the location of scattering material along the line of sight (LoS) to pulsars, scintillation arcs are a powerful tool for exploring the distribution of ionized material in the interstellar medium. Here, we present observations that probe the ionized ISM on scales of $\sim$~0.001 -- 30~au. Aims: We have surveyed pulsars for scintillation arcs in a relatively unbiased sample with DM < 100 pc cm-3. We present multi-frequency observations of 22 low to moderate DM pulsars. Many of the 54 observations were also observed at another frequency within a few days. Methods: For all observations we present dynamic spectra, autocorrelation functions, and secondary spectra. We analyze these data products to obtain scintillation bandwidths, pulse broadening times, and arc curvatures. Results: We detect definite or probable scintillation arcs in 19 of the 22 pulsars and 34 of the 54 observations, showing that scintillation arcs are a prevalent phenomenon. The arcs are better defined in low DM pulsars. We show that well-defined arcs do not directly imply anisotropy of scattering. Only the presence of reverse arclets and a deep valley along the delay axis, which occurs in about 20\% of the pulsars in the sample, indicates substantial anisotropy of scattering. Conclusions: The survey demonstrates substantial patchiness of the ionized ISM on both au size scales transverse to the line of sight and on $\sim$~100~pc scales along it. We see little evidence for distributed scattering along most lines of sight in the survey.
description: 34 pages, 5 tables, 12 figures. In addition, there are two figure sets, one with 54 .png files in it and one with 22 .png files in it. These are included in the /anc directory
Spin conductance of YIG thin films driven from thermal to subthermal magnons regime by large spin-orbit torque
Creators: name: Thiery, Nicolas
name: Draveny, Antoine
name: Naletov, Vladimir V.
name: Vila, Laurent
name: Attané, Jean-Philippe
name: de Loubens, Grégoire
name: Viret, Michel
name: Beaulieu, Nathan
name: Youssef, Jamal Ben
name: Demidov, Vladislav E.
name: Demokritov, Sergej O.
name: Slavin, Andrei N.
name: Tiberkevich, Vasyl S.
name: Anane, Abdelmadjid
name: Bortolotti, Paolo
name: Cros, Vincent
name: Klein, Olivier
Publisher: name: arXiv
Year: 2017
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: We report a study on spin conductance in ultra-thin films of Yttrium Iron Garnet (YIG), where spin transport is provided by propagating spin waves, that are generated and detected by direct and inverse spin Hall effects in two Pt wires deposited on top. While at low current the spin conductance is dominated by transport of thermal magnons, at high current, the spin conductance is dominated by low-damping non-equilibrium magnons thermalized near the spectral bottom by magnon-magnon interaction, with consequent a sensitivity to the applied magnetic field and a longer decay length. This picture is supported by microfocus Brillouin Light Scattering spectroscopy.
Particle Asymmetries from Quantum Statistics
Creators: name: Blinov, Nikita
name: Hook, Anson
Publisher: name: arXiv
Year: 2017
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: We consider a class of baryogenesis models where the Lagrangian in the visible sector is Charge-Parity (CP) invariant and a baryon asymmetry is produced only when quantum statistics is taken into account. The CP symmetry is broken by matter effects, namely the assumption that the primordial plasma contains another asymmetric species, such as dark matter. Out-of-equilibrium baryon number violating decays can then generate an asymmetry through Bose enhancement and/or Pauli blocking of certain decay channels.
description: Minor changes to match journal version
Precision measurements of the zero temperature dielectric constant and density of liquid $^4$He
Creators: name: Learn, R. T.
name: Varga, E.
name: Vadakkumbatt, V.
name: Davis, J. P.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Other Condensed Matter (cond-mat.other)
subject: FOS: Physical sciences

description: The resonant frequencies of three-dimensional microwave cavities are explicitly dependent on the dielectric constant of the material filling the cavity, making them an ideal system for probing material properties. In particular, dielectric constant measurements allow one to extract the helium density through the Clausius-Mossotti relation. By filling a cylindrical aluminum cavity with superfluid helium, we make precision measurements of the dielectric constant of liquid $^4$He at saturated vapor pressure for range of temperatures 30 -- 300 mK and at pressures of 0-25.0 bar at 30 mK, essentially the zero temperature limit for the properties of $^4$He. After reviewing previous measurements, we find systematic discrepancy between low and high frequency determination of the dielectric constant in the zero-temperature limit and moderate discrepancy with previously reported values of pressure-dependent density. Our precision measurements suggest 3D microwave cavities are a promising choice for refining previously measured values in helium, with potential applications in metrology.
description: 10 pages, 9 figures
Long-lived Solitons and Their Signatures in the Classical Heisenberg Chain
Creators: name: McRoberts, Adam J.
name: Bilitewski, Thomas
name: Haque, Masudul
name: Moessner, Roderich
Publisher: name: arXiv
Year: 2022
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Exactly Solvable and Integrable Systems (nlin.SI)
subject: FOS: Physical sciences

description: Motivated by the KPZ scaling recently observed in the classical ferromagnetic Heisenberg chain, we investigate the role of solitonic excitations in this model. We find that the Heisenberg chain, although well-known to be non-integrable, supports a two-parameter family of long-lived solitons. We connect these to the exact soliton solutions of the integrable Ishimori chain with $\log(1+ S_i\cdot S_j)$ interactions. We explicitly construct infinitely long-lived stationary solitons, and provide an adiabatic construction procedure for moving soliton solutions, which shows that Ishimori solitons have a long-lived Heisenberg counterpart when they are not too narrow and not too fast-moving. Finally, we demonstrate their presence in thermal states of the Heisenberg chain, even when the typical soliton width is larger than the spin correlation length, and argue that these excitations likely underlie the KPZ scaling.
description: 4 + 6 pages, 4 + 6 figures
The spectral symmetry of weakly irreducible nonnegative tensors and connected hypergraphs
Creators: name: Fan, Yi-Zheng
name: Huang, Tao
name: Bao, Yan-Hong
name: Zhuan-Sun, Chen-Lu
name: Li, Ya-Ping
Publisher: name: arXiv
Year: 2017
Subjects: subject: Combinatorics (math.CO)
subject: FOS: Mathematics
subject: 15A18, 05C65, 13P15, 05C15

description: Let $\mathcal{A}$ be a weakly irreducible nonnegative tensor with spectral radius $ρ(\mathcal{A})$. Let $\mathfrak{D}$ (respectively, $\mathfrak{D}^{(0)}$) be the set of normalized diagonal matrices arising from the eigenvectors of $\mathcal{A}$ corresponding to the eigenvalues with modulus $ρ(\mathcal{A})$ (respectively, the eigenvalue $ρ(\mathcal{A})$). It is shown that $\mathfrak{D}$ is an abelian group containing $\mathfrak{D}^{(0)}$ as a subgroup, which acts transitively on the set $\{e^{\mathbf{i} \frac{2 πj}{\ell}}\mathcal{A}:j =0,1, \ldots,\ell-1\}$, where $|\mathfrak{D}/\mathfrak{D}^{(0)}|=\ell$ and $\mathfrak{D}^{(0)}$ is the stabilizer of $\mathcal{A}$. The spectral symmetry of $\mathcal{A}$ is characterized by the group $\mathfrak{D}/\mathfrak{D}^{(0)}$, and $\mathcal{A}$ is called spectral $\ell$-symmetric. We obtain the structural information of $\mathcal{A}$ by analyzing the property of $\mathfrak{D}$, especially for connected hypergraphs we get some results on the edge distribution and coloring. If moreover $\mathcal{A}$ is symmetric, we prove that $\mathcal{A}$ is spectral $\ell$-symmetric if and only if it is $(m,\ell)$-colorable. We characterize the spectral $\ell$-symmetry of a tensor by using its generalized traces, and show that for an arbitrarily given integer $m \ge 3$ and each positive integer $\ell$ with $\ell \mid m$, there always exists an $m$-uniform hypergraph $G$ such that $G$ is spectral $\ell$-symmetric.
Chiral effects in astrophysics and cosmology
Creators: name: Kamada, Kohei
name: Yamamoto, Naoki
name: Yang, Di-Lun
Publisher: name: arXiv
Year: 2022
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: Nuclear Theory (nucl-th)
subject: FOS: Physical sciences

description: The microscopic quantum nature of elementary particles, chirality, leads to macroscopic phenomena like the chiral anomaly, chiral magnetic effect, and chiral plasma instability. We review recent progress of the studies of these chiral effects in high-energy astrophysics, such as pulsar kicks, magnetars, and core-collapse supernovae, and early Universe cosmology, such as the primordial magnetic field, baryogenesis, and chiral gravitational waves. We also provide a pedagogical introduction to the chiral effects and low-energy effective theories to describe them in and out of equilibrium -- the chiral (magneto)hydrodynamics, chiral kinetic theory, and chiral radiation transport theory for neutrinos.
description: 76 pages, 4 figures; v2: minor revisions, version to appear in Progress in Particle and Nuclear Physics
Polynomial Threshold Functions for Decision Lists
Creators: name: Podolskii, Vladimir
name: Proskurin, Nikolay V.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Computational Complexity (cs.CC)
subject: FOS: Computer and information sciences

description: For $S \subseteq \{0,1\}^n$ a Boolean function $f \colon S \to \{-1,1\}$ is a polynomial threshold function (PTF) of degree $d$ and weight $W$ if there is a polynomial $p$ with integer coefficients of degree $d$ and with sum of absolute coefficients $W$ such that $f(x) = \text{sign}(p(x))$ for all $x \in S$. We study a representation of decision lists as PTFs over Boolean cubes $\{0,1\}^n$ and over Hamming balls $\{0,1\}^{n}_{\leq k}$. As our first result, we show that for all $d = O\left( \left( \frac{n}{\log n}\right)^{1/3}\right)$ any decision list over $\{0,1\}^n$ can be represented by a PTF of degree $d$ and weight $2^{O(n/d^2)}$. This improves the result by Klivans and Servedio [Klivans, Servedio, 2006] by a $\log^2 d$ factor in the exponent of the weight. Our bound is tight for all $d = O\left( \left( \frac{n}{\log n}\right)^{1/3}\right)$ due to the matching lower bound by Beigel [Beigel, 1994]. For decision lists over a Hamming ball $\{0,1\}^n_{\leq k}$ we show that the upper bound on weight above can be drastically improved to $n^{O(\sqrt{k})}$ for $d = Θ(\sqrt{k})$. We also show that similar improvement is not possible for smaller degrees by proving the lower bound $W = 2^{Ω(n/d^2)}$ for all $d = O(\sqrt{k})$. \end{abstract}
description: 14 pages in total (11 for article + 3 for references and appendix)
Uncovering a hidden black hole binary from secular eccentricity variations of a tertiary star
Creators: name: Liu, Bin
name: D'Orazio, Daniel J.
name: Vigna-Gómez, Alejandro
name: Samsing, Johan
Publisher: name: arXiv
Year: 2022
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: We study the dynamics of a solar-type star orbiting around a black hole binary (BHB) in a nearly coplanar system. We present a novel effect that can prompt a growth and significant oscillations of the eccentricity of the stellar orbit when the system encounters an "apsidal precession resonance", where the apsidal precession rate of the outer stellar orbit matches that of the inner BHB. The eccentricity excitation requires the inner binary to have a non-zero eccentricity and unequal masses, and can be created even in non-coplanar triples. We show that the secular variability of the stellar orbit's apocenter, induced by the changing eccentricity, could be potentially detectable by \textit{Gaia}. Detection is favorable for BHBs emitting gravitational waves in the frequency band of the Laser Interferometer Space Antenna (LISA), hence providing a distinctive, multi-messenger probe on the existence of stellar-mass BHBs in the Milky Way.
description: 9 pages, 7 figures, accepted for publication in PRD
Vortex-enabled Andreev processes in quantum Hall-superconductor hybrids
Creators: name: Tang, Yuchen
name: Knapp, Christina
name: Alicea, Jason
Publisher: name: arXiv
Year: 2022
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Superconductivity (cond-mat.supr-con)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Quantum Hall-superconductor heterostructures provide possible platforms for intrinsically fault-tolerant quantum computing. Motivated by several recent experiments that successfully integrated these phases, we investigate transport through a proximitized integer quantum Hall edge--paying particular attention to the impact of vortices in the superconductor. By examining the downstream conductance, we identify regimes in which sub-gap vortex levels mediate Andreev processes that would otherwise be frozen out in a vortex-free setup. Moreover, we show that at finite temperature, and in the limit of a large number of vortices, the downstream conductance can average to zero, indicating that the superconductor effectively behaves like a normal contact. Our results highlight the importance of considering vortices when using transport measurements to study superconducting correlations in quantum Hall-superconductor hybrids.
description: 16 pages, 9 figures
Evaluation of test-day milk somatic cell count to predict intramammary infection in late lactation grazing dairy cows
Creators: name: Clabby, Clare
name: Valldecabres, A.
name: Dillon, P.
name: McParland, S.
name: ARKINS, SEAN
name: O’Sullivan, K
name: Flynn, J.
name: Murphy, J.
name: Silva Boloña, P.
Publisher: name: University of Limerick
Year: 2023
Subjects: subject: Biological sciences
subject: FOS: Biological sciences

description: The use of selective dry cow antimicrobial therapy requires precisely differentiating cows with an intramammary infection (IMI) from uninfected cows close to drying-off to enable treatment allocation. Milk somatic cell count (SCC) is an indicator of an inflammatory response in the mammary gland and is usually associated with IMI. However, SCC can also be influenced by cow-level variables such as milk yield, lactation number, and stage of lactation. In recent years, predictive algorithms have been developed to differentiate cows with IMI from cows without IMI based on SCC data. The objective of this observational study was to explore the association between SCC and subclinical IMI, taking cognizance of cow-level predictors on Irish seasonal spring calving, pasture-based systems. Additionally, the optimal test-day SCC cut-point (maximized sensitivity and specificity) for IMI diagnosis was determined. A total of 2,074 cows across 21 spring calving dairy herds with an average monthly milk weighted bulk tank SCC of ≤200,000 cells/mL were enrolled in the study. Quarter-level milk sampling was carried out on all cows in late lactation (interquartile range = 240–261 d in milk) for bacteriological culturing. Bacteriological results were used to define cows with IMI when ≥1 quarter sample resulted in bacterial growth. Cow-level test-day SCC records were provided by the herd owners. The ability of the average, maximum, and last test-day SCC to predict infection were compared using receiver operator curves. Predictive logistic regression models tested included parity (primiparous or multiparous), yield at last test-day, and a standardized count of high SCC test-days. In total, 18.7% of cows were classified as having an IMI, with first-parity cows having a higher proportion of IMI (29.3%) compared with multiparous cows (16.1%). Staphylococcus aureus accounted for the majority of these infections. The last test-day SCC was the best predictor of infection with the highest area under the curve. The inclusions of parity, yield at last test-day, and a standardized count of high SCC test-days as predictors did not significantly improve the ability of last test-day SCC to predict IMI. The cut-point for last test-day SCC that maximized sensitivity and specificity was 64,975 cells/mL. This study indicates that in Irish seasonal pasture-based dairy herds with low bulk tank SCC, the last test-day SCC (interquartile range days in milk = 221–240) is the best predictor of IMI in late lactation.
Violation of the virial theorem and generalized equipartition theorem for logarithmic oscillators serving as a thermostat
Creators: name: Chen, Kai
name: He, Dahai
name: Zhao, Hong
Publisher: name: arXiv
Year: 2016
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Computational Physics (physics.comp-ph)
subject: FOS: Physical sciences

description: A logarithmic oscillator has been proposed recently to serve as a thermostat recently since it has a peculiar property of infinite heat capacity according to the virial theorem. In order to examine its feasibility by numerical simulations, a modified logarithmic potential has been applied in previous studies to eliminate the singularity at origin. The role played by the modification has been elucidated in the present study. We argue that the virial theorem is practically violated for the modified log-oscillator illustrated by a linear dependence of kinetic temperature on energy. Furthermore, as far as a thermalized log-oscillator is concerned, the generalized equipartition theorem with respect to the position coordinate is broken if the temperature is higher than a critical temperature. Finally, we show that log-oscillators fail to serve as thermostats for its incapability of maintaining a nonequilibrium steady state even though their energy is appropriately assigned.
description: 6 pages, 6 figures
Epitaxial electrical contact to graphene on SiC
Creators: name: Quang, T. Le
name: Huder, L.
name: Bregolin, F. Lipp
name: Artaud, A.
name: Okuno, H.
name: Pouget, S.
name: Mollard, N.
name: Lapertot, G.
name: Jansen, A. G. M
name: Lefloch, F.
name: Driessen, E. F. C
name: Chapelier, C.
name: Renard, V. T.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Applied Physics (physics.app-ph)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: Establishing good electrical contacts to nanoscale devices is a major issue for modern technology and contacting 2D materials is no exception to the rule. One-dimensional edge-contacts to graphene were recently shown to outperform surface contacts but the method remains difficult to scale up. We report a resist-free and scalable method to fabricate few graphene layers with electrical contacts in a single growth step. This method derives from the discovery reported here of the growth of few graphene layers on a metallic carbide by thermal annealing of a carbide forming metallic film on SiC in high vacuum. We exploit the combined effect of edge-contact and partially-covalent surface epitaxy between graphene and the metallic carbide to fabricate devices in which low contact-resistance and Josephson effect are observed. Implementing this approach could significantly simplify the realization of large-scale graphene circuits.
description: supplementary information available at the publisher's site
Distinguishing Dark Matter, Modified Gravity, and Modified Inertia with the Inner and Outer Parts of Galactic Rotation Curves
Creators: name: Chae, Kyu-Hyun
Publisher: name: arXiv
Year: 2022
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: The missing gravity in galaxies requires dark matter, or alternatively a modification of gravity or inertia. These theoretical possibilities of fundamental importance may be distinguished by the statistical relation between the observed centripetal acceleration of particles in orbital motion and the expected Newtonian acceleration from the observed distribution of baryons in galaxies. Here predictions of cold dark matter halos, modified gravity, and modified inertia are compared and tested by a statistical sample of galaxy rotation curves from the Spitzer Photometry and Accurate Rotation Curves (SPARC) database. Modified gravity under an estimated mean external field correctly predicts the observed statistical relation of accelerations from both the inner and outer parts of rotation curves. Taken at face value there is a $6.9σ$ difference between the inner and outer parts on an acceleration plane which would be inconsistent with current proposals of modified inertia. Removing galaxies with possible systematic concerns such as central bulges or special inclinations does not change this trend. Cold dark matter halos predict a systematically deviating relation from the observed one. All aspects of rotation curves are most naturally explained by modified gravity.
description: ApJ, in press (results revised, conclusions unchanged)
Investigating the Role of Socially Mediated Metacognition During Collaborative Troubleshooting of Electric Circuits
Creators: name: Van De Bogart, Kevin L.
name: Dounas-Frazer, Dimitri R.
name: Lewandowski, H. J.
name: Stetzer, MacKenzie R.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Physics Education (physics.ed-ph)
subject: FOS: Physical sciences

description: Developing students' ability to troubleshoot is an important learning outcome for many undergraduate physics lab courses, especially electronics courses. In other work, metacognition has been identified as an important feature of troubleshooting. However, that work has focused primarily on individual students' metacognitive processes or troubleshooting abilities. In contrast, electronics courses often require students to work in pairs, and hence students' in-class experiences likely have significant social dimensions that are not well understood. In this work, we use an existing framework for socially mediated metacognition to analyze audiovisual data from think-aloud activities in which eight pairs of students from two institutions attempted to diagnose and repair a malfunctioning electric circuit. In doing so, we provide insight into some of the social metacognitive dynamics that arise during collaborative troubleshooting. We find that students engaged in socially mediated metacognition at multiple key transitions during the troubleshooting process. Reciprocated metacognitive dialogue arose when students were collectively strategizing about which measurements to perform, or reaching a shared understanding of the circuit's behavior. In addition to elaborating upon these findings, we discuss implications for instruction, and we identify areas for potential future investigation.
Propagation of Partially Coherent Light in non-Hermitian Lattices
Creators: name: Brandão, P. A.
name: Rocha, J. C. A.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: Band theory for partially coherent light is introduced by using the formalism of second-order classical coherence theory under paraxial approximation. It is demonstrated that the cross-spectral density function, describing correlations between pairs of points in the field, can have bands and gaps and form a correlation band structure. The propagation of a partially coherent beam in non-Hermitian periodic structures is considered to elucidate the interplay between the degree of coherence and the gain/loss present in the lattice. We apply the formalism to study partially coherent Bloch oscillations in lattices having parity-time symmetry and demonstrate that the oscillations can be sustained in such media but they are strongly dependent upon the spatial correlations of the beam. A transition between breathing and oscillating modes is shown to be induced by the degree of spatial coherence.
Assessing effects of cortical injury on the locus coeruleus
Creators: name: Pandya, Mansi A.
Publisher: name: No Publisher Supplied
Year: 2022

description: Traumatic Brain Injury (TBI) causes neuronal cell death in local area of impact. However, these injuries may also have degenerative effects retrogradely in the afferent neurons that project to the injured areas, which can have long-term consequences. Examining TBI to the cortex can show which populations of neurons are affected by such injuries. TBI has been known to cause necrotic cell death at the core of the injury, and over time cause secondary neuronal loss. Studies have shown that the innervating afferent neurons that project to the site of injury also experience a local trophic change in their target regions, and this may lead to a retrograde degeneration of these neurons. There are many populations of neurons that have afferent innervation to the cortex. Our lab is looking at two populations of these afferent neuronal populations. The cholinergic neurons of the basal forebrain and the noradrenergic neurons of the Locus coeruleus. The loss of neurons during a TBI have been shown to contribute to development of neurodegenerative diseases later in life. A population of neurons that show degenerative effects in cognitive degenerative disease states are the noradrenergic (NA) neurons of the Locus Coeruleus (LC). Therefore, our lab is investigating if projecting neuronal populations such as the basal forebrain (BF) are affected by the cortical injury. Preliminary studies show that there is ipsilateral BF loss. From these observations about the BF neurons, we wanted to investigate whether this loss would be present in a different population of neurons. In this study we investigated the effects of cortical injury on the noradrenergic neurons of the Locus Coeruleus.
Adaptive Neural Networks for Efficient Inference
Creators: name: Bolukbasi, Tolga
name: Wang, Joseph
name: Dekel, Ofer
name: Saligrama, Venkatesh
Publisher: name: arXiv
Year: 2017
Subjects: subject: Machine Learning (cs.LG)
subject: Computer Vision and Pattern Recognition (cs.CV)
subject: Neural and Evolutionary Computing (cs.NE)
subject: Machine Learning (stat.ML)
subject: FOS: Computer and information sciences

description: We present an approach to adaptively utilize deep neural networks in order to reduce the evaluation time on new examples without loss of accuracy. Rather than attempting to redesign or approximate existing networks, we propose two schemes that adaptively utilize networks. We first pose an adaptive network evaluation scheme, where we learn a system to adaptively choose the components of a deep network to be evaluated for each example. By allowing examples correctly classified using early layers of the system to exit, we avoid the computational time associated with full evaluation of the network. We extend this to learn a network selection system that adaptively selects the network to be evaluated for each example. We show that computational time can be dramatically reduced by exploiting the fact that many examples can be correctly classified using relatively efficient networks and that complex, computationally costly networks are only necessary for a small fraction of examples. We pose a global objective for learning an adaptive early exit or network selection policy and solve it by reducing the policy learning problem to a layer-by-layer weighted binary classification problem. Empirically, these approaches yield dramatic reductions in computational cost, with up to a 2.8x speedup on state-of-the-art networks from the ImageNet image recognition challenge with minimal (<1%) loss of top5 accuracy.
Decay properties of $P$-wave charmed baryons from light-cone QCD sum rules
Creators: name: Chen, Hua-Xing
name: Mao, Qiang
name: Chen, Wei
name: Hosaka, Atsushi
name: Liu, Xiang
name: Zhu, Shi-Lin
Publisher: name: arXiv
Year: 2017
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Experiment (hep-ex)
subject: High Energy Physics - Lattice (hep-lat)
subject: FOS: Physical sciences

description: We study decay properties of the $P$-wave charmed baryons using the method of light-cone QCD sum rules, including the $S$-wave decays of the flavor $\mathbf{\bar 3}_F$ $P$-wave charmed baryons into ground-state charmed baryons accompanied by a pseudoscalar meson ($π$ or $K$) or a vector meson ($ρ$ or $K^*$), and the $S$-wave decays of the flavor $\mathbf{6}_F$ $P$-wave charmed baryons into ground-state charmed baryons accompanied by a pseudoscalar meson ($π$ or $K$). We study both two-body and three-body decays which are kinematically allowed. We find two mixing solutions from internal $ρ$- and $λ$-mode excitations, which can well describe both masses and decay properties of the $Λ_c(2595)$, $Λ_c(2625)$, $Ξ_c(2790)$ and $Ξ_c(2815)$. We also discuss the possible interpretations of $P$-wave charmed baryons for the $Σ_c(2800)$, $Ξ_c(2930)$, $Ξ_c(2980)$, and the recently observed $Ω_c(3000)$, $Ω_c(3050)$, $Ω_c(3066)$, $Ω_c(3090)$, and $Ω_c(3119)$.
description: 44 pages, 9 figures. Version appears in Phys. Rev. D
Breakdown of optical phonons' splitting in two-dimensional materials
Creators: name: Sohier, Thibault
name: Gibertini, Marco
name: Calandra, Matteo
name: Mauri, Francesco
name: Marzari, Nicola
Publisher: name: arXiv
Year: 2016
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: We investigate the long-wavelength dispersion of longitudinal and transverse optical phonon modes in polar two-dimensional materials, multilayers, and their heterostructures. Using analytical models and density-functional perturbation theory in a two-dimensional framework, we show that, at variance with the three-dimensional case, these modes are degenerate at the zone center but the macroscopic electric field associated with the longitudinal-optical modes gives rise to a finite slope at the zone center in their corresponding phonon dispersions. This slope increases linearly with the number of layers and it is determined solely by the Born effective charges of the material and the dielectric properties of the surrounding media. Screening from the environment can greatly reduce the slope splitting between the longitudinal and transverse optical modes and can be seen in the experimentally relevant case of boron nitride-graphene heterostructures. As the phonon momentum increases, the intrinsic screening properties of the two-dimensional material dictate the transition to a momentum-independent splitting similar to that of three-dimensional materials. These considerations are essential to understand electrical transport and optical coupling in two-dimensional systems.
description: 8 pages, 4 figures
Report on Waste Pollution in Stations.pdf
Creators: name: North, McKenna
Publisher: name: figshare
Year: 2024
Subjects: classificationCode: 440404
subject: Political economy and social change
classificationCode: 440405
subject: Poverty, inclusivity and wellbeing
classificationCode: 440407
subject: Socio-economic development
classificationCode: 440408
subject: Urban community development

description: This report aims to document the extent of plastic waste pollution in lorry stations in Accra, assess its impact on public health and propose actionable solutions for effective waste management in stations. By highlighting the severity of the issue as well as providing recommendations for solutions, we seek to inform and inspire municipal assemblies, policymakers and other stakeholders to take decisive action against plastic waste pollution in lorry stations in Accra. Plastic waste pollution is a growing concern in Ghana, with lorry stations being particularly affected due to high foot traffic and inadequate waste management infrastructure within stations. This report is significant because of its implications for addressing public health hazards, continuing the ongoing efforts to reduce plastic pollution in Ghana and addressing community concerns. Through this comprehensive analysis, Mckingtorch Africa aims to drive meaningful change and create a cleaner, healthier Ghana for present and future generations.