cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Consistent Constraints on the Equivalence Principle from localised Fast Radio Bursts
Creators: name: Reischke, Robert
name: Hagstotz, Steffen
Publisher: name: arXiv
Year: 2023
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: Astrophysics of Galaxies (astro-ph.GA)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: Fast Radio Bursts (FRBs) are short astrophysical transients of extragalactic origin. Their burst signal is dispersed by the free electrons in the large-scale-structure (LSS), leading to delayed arrival times at different frequencies. Another potential source of time delay is the well known Shapiro delay, which measures the space-space and time-time metric perturbations along the line-of-sight. If photons of different frequencies follow different trajectories, i.e. if the universality of free fall guaranteed by the weak equivalence principle (WEP) is violated, they would experience an additional relative delay. This quantity, however, is not an observable on the background level as it is not gauge independent, which has led to confusion in previous papers. Instead, an imprint can be seen in the correlation between the time delays of different pulses. In this paper, we derive robust and consistent constraints from twelve localised FRBs on the violation of the WEP in the energy range between 4.6 and 6 meV. In contrast to a number of previous studies, we consider our signal to be not in the model, but in the covariance matrix of the likelihood. To do so, we calculate the covariance of the time delays induced by the free electrons in the LSS, the WEP breaking terms, the Milky Way and host galaxy. By marginalising over both host galaxy contribution and the contribution from the free electrons, we find that the parametrised post-Newtonian parameter $γ$ characterising the WEP violation must be constant in this energy range to 1 in $10^{13}$ at 68$\;\%$ confidence. These are the tightest constraints to-date on $Δγ$ in this low energy range.
description: 8 pages, 4 figures, accepted by MNRAS, matches final submitted
Group influence, mass media, and musical taste: a study of third year male students in the University of Calgary
Creators: name: Heath, Carole Lynn
Publisher: name: University of Calgary
Year: 1972
Subjects: subject: HM 258 H42 1972
subject: Mass media
subject: Culture
subject: Communication
subject: Music - Philosophy and aesthetics
subject: Social groups

description: Bibliography: p. 95-103.
Physical Structure of the Planetary Nebula NGC 3242 from the Hot Bubble to the Nebular Envelope
Creators: name: Ruiz, Nieves
name: Guerrero, Martin A.
name: Chu, You-Hua
name: Gruendl, Robert A.
Publisher: name: arXiv
Year: 2011
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: One key feature of the interacting stellar winds model of the formation of planetary nebulae (PNe) is the presence of shock-heated stellar wind confined in the central cavities of PNe. This so-called hot bubble should be detectable in X-rays. Here we present XMM-Newton observations of NGC 3242, a multiple-shell PN whose shell morphology is consistent with the interacting stellar winds model. Diffuse X-ray emission is detected within its inner shell with a plasma temperature ~2.35\times10^6 K and an intrinsic X-ray luminosity ~2\times10^30 ergs s^(-1) at the adopted distance of 0.55 kpc. The observed X-ray temperature and luminosity are in agreement with "ad-hoc" predictions of models including heat conduction. However, the chemical abundances of the X-ray-emitting plasma seem to imply little evaporation of cold material into the hot bubble, whereas the thermal pressure of the hot gas is unlikely to drive the nebular expansion as it is lower than that of the inner shell rim. These inconsistencies are compounded by the apparent large filling factor of the hot gas within the central cavity of NGC 3242. Subject headings: planetary nebulae: individual (NGC 3242)
description: Accepted the publication in Astronomical Journal
Insuring against future climate change : the use of mandatory catastrophe risk insurance and microinsurance to promote mitigation and adaptation
Creators: name: Telesetsky, Anastasia M.
Publisher: name: University of British Columbia
Year: 2009

description: This thesis examines the potential of insurance to reduce greenhouse house gas emissions and help societies to equitably adapt to predicted gradual and catastrophic climate change impacts. The paper explores how insurance might operate as a mitigation and adaptation tool for states and enterprises with high-coping capacities and proposes a new insurance product: climate change catastrophe risk insurance. As explained in the paper, the proposed catastrophe risk insurance would further the goals of implementing the polluter pays principle in the context of climate change. The paper also examines how insurance might be used as an adaptation tool for vulnerable groups and individuals with low-coping capacities and proposes a regionally distributed microinsurance product to be funded by proposed national or global carbon taxes.
Improved dimension dependence of a proximal algorithm for sampling
Creators: name: Fan, Jiaojiao
name: Yuan, Bo
name: Chen, Yongxin
Publisher: name: arXiv
Year: 2023
Subjects: subject: Statistics Theory (math.ST)
subject: Machine Learning (stat.ML)
subject: FOS: Mathematics
subject: FOS: Computer and information sciences

description: We propose a sampling algorithm that achieves superior complexity bounds in all the classical settings (strongly log-concave, log-concave, Logarithmic-Sobolev inequality (LSI), Poincaré inequality) as well as more general settings with semi-smooth or composite potentials. Our algorithm is based on the proximal sampler introduced in~\citet{lee2021structured}. The performance of this proximal sampler is determined by that of the restricted Gaussian oracle (RGO), a key step in the proximal sampler. The main contribution of this work is an inexact realization of RGO based on approximate rejection sampling. To bound the inexactness of RGO, we establish a new concentration inequality for semi-smooth functions over Gaussian distributions, extending the well-known concentration inequality for Lipschitz functions. Applying our RGO implementation to the proximal sampler, we achieve state-of-the-art complexity bounds in almost all settings. For instance, for strongly log-concave distributions, our method has complexity bound $\tilde\mathcal{O}(κd^{1/2})$ without warm start, better than the minimax bound for MALA. For distributions satisfying the LSI, our bound is $\tilde \mathcal{O}(\hat κd^{1/2})$ where $\hat κ$ is the ratio between smoothness and the LSI constant, better than all existing bounds.
Dynamical behavior of the Niedermayer algorithm applied to Potts models
Creators: name: Girardi, D.
name: Penna, T. J. P.
name: Branco, N. S.
Publisher: name: arXiv
Year: 2012
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Computational Physics (physics.comp-ph)
subject: FOS: Physical sciences

description: In this work we make a numerical study of the dynamic universality class of the Niedermayer algorithm applied to the two-dimensional Potts model with 2, 3, and 4 states. This algorithm updates clusters of spins and has a free parameter, $E_0$, which controls the size of these clusters, such that $E_0=1$ is the Metropolis algorithm and $E_0=0$ regains the Wolff algorithm, for the Potts model. For $-10$, spins in different states may be added to the cluster but the dynamic behavior is less efficient than for the Wolff algorithm ($E_0=0$). Therefore, our results show that the Wolff algorithm is the best choice for Potts models, when compared to the Niedermayer's generalization.
description: 10 pages, 11 figures, to be published in Physica A. arXiv admin note: substantial text overlap with arXiv:1003.3655
Designing an Industry-Relevant Competency-based Computer Networking Curriculum: An Innovative and Blended Learning Approach to Enhance the Immersive Learning Experience at Dominica State College.
Creators: name: Malisa Richards
Publisher: name: Open Science Framework
Year: 2023
Subjects: subject: Education
subject: Blended learning approaches with emerging technology integration
subject: AR & VR Integration into Classe365 and Moodle LMS

description: This is a three-part research where part 1 via Namseoul University master's degree dissertation will demonstrate how Classe365 SIS and Moodle LMS can effectively integrate AR & VR technologies and blended learning approaches into the computer networking curriculum. Prof Robert Dean (Research Supervisor) of Namseoul University will guide the technology integration.
A lensed radio jet at milli-arcsecond resolution II: Constraints on fuzzy dark matter from an extended gravitational arc
Creators: name: Powell, Devon M.
name: Vegetti, Simona
name: McKean, J. P.
name: White, Simon D. M.
name: Ferreira, Elisa G. M.
name: May, Simon
name: Spingola, Cristiana
Publisher: name: arXiv
Year: 2023
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: Using a single gravitational lens system observed at $\lesssim5$ milli-arcsecond resolution with very long baseline interferometry (VLBI), we place a lower bound on the mass of the fuzzy dark matter (FDM) particle, ruling out $m_χ\leq 4.4\times10^{-21}~\mathrm{eV}$ with a 20:1 posterior odds ratio relative to a smooth lens model. We generalize our result to non-scalar and multiple-field models, such as vector FDM, with $m_{χ,\mathrm{vec}} > 1.4 \times 10^{-21}~\mathrm{eV}$. Due to the extended source structure and high angular resolution of the observation, our analysis is directly sensitive to the presence of granule structures in the main dark matter halo of the lens, which is the most generic prediction of FDM theories. A model based on well-understood physics of ultra-light dark matter fields in a gravitational potential well makes our result robust to a wide range of assumed dark matter fractions and velocity dispersions in the lens galaxy. Our result is competitive with other lower bounds on $m_χ$ from past analyses, which rely on intermediate modelling of structure formation and/or baryonic effects. Higher resolution observations taken at 10 to 100 GHz could improve our constraints by up to 2 orders of magnitude in the future.
description: 5 pages, 2 figures. Accepted in MNRAS Letters
The 1/m expansion in spin glasses and the de Almeida-Thouless line
Creators: name: Moore, M. A.
Publisher: name: arXiv
Year: 2012
Subjects: subject: Disordered Systems and Neural Networks (cond-mat.dis-nn)
subject: FOS: Physical sciences

description: It is shown by means of a 1/m expansion about the large-m limit of the m-vector spin glass that the lower critical dimension of the de Almeida-Thouless line in spin glasses is equal to the lower critical dimension of the large-m limit of the m-vector spin glass. Numerical studies suggest that this is close to six.
description: 8 pages
A NICER viewing angle on the accretion stream of Vela X-1
Creators: name: Rahin, Roi
name: Behar, Ehud
Publisher: name: arXiv
Year: 2023
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: Vela X-1 is the archetypical eclipsing high-mass X-ray binary, composed of a neutron star (NS) accreting the B-star wind. It was observed by nearly all X-ray observatories, often multiple times, featuring a rich spectrum of variable emission lines. Yet, the precise origin of these lines in the binary system remains uncertain. We perform a systematic, orbital phase-dependent analysis of the reflected Fe K$α$ fluorescence line at 6.4 keV using over 100 NICER observations. We resolve the line variability into 500s time bins and find that it is predominantly due to variation in the ionizing flux, with a moderate underlying phase dependence over the 9-day orbital period. Our analysis reveals a significant reflection component that cannot originate from the companion B-star alone. We also find that an appreciable portion of the B-star surface is obscured opposite the eclipse, and this obscuration is not symmetric around the mid-point (phase=0.5). We argue that an accretion stream, from the B-star to the NS and distorted by the orbital motion, is responsible for both the additional fluorescence emission component and for obscuring the B-star.
description: Submitted to ApJ
Ladder and zig-zag Feynman diagrams, operator formalism and conformal triangles
Creators: name: Derkachov, S. E.
name: Isaev, A. P.
name: Shumilov, L. A.
Publisher: name: arXiv
Year: 2023
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We develop an operator approach to the evaluation of multiple integrals for multiloop Feynman massless diagrams. A commutative family of graph building operators $H_α$ for ladder diagrams is constructed and investigated. The complete set of eigenfunctions and the corresponding eigenvalues for the operators $H_α$ are found. This enables us to explicitly express a wide class of four-point ladder diagrams and a general two-loop propagator-type master diagram (with arbitrary indices on the lines) as Mellin-Barnes-type integrals. Special cases of these integrals are explicitly evaluated. A certain class of zig-zag four-point and two-point planar Feynman diagrams (relevant to the bi-scalar $D$-dimensional "fishnet" field theory and to the calculation of the $β$-function in $ϕ^4$-theory) is considered. The graph building operators and convenient integral representations for these Feynman diagrams are obtained. The explicit form of the eigenfunctions for the graph building operators of the zig-zag diagrams is fixed by conformal symmetry and these eigenfunctions coincide with the 3-point correlation functions in $D$-dimensional conformal field theories. By means of this approach, we exactly evaluate the diagrams of the zig-zag series in special cases. In particular, we find a fairly simple derivation of the values for the zig-zag multi-loop two-point diagrams for $D=4$. The role of conformal symmetry in this approach, especially a connection of the considered graph building operators with conformal invariant solutions of the Yang-Baxter equation is investigated in detail.
Optimized Si/SiO2 high contrast grating mirror design for mid-infrared wavelength range: robustness enhancement
Creators: name: Chevallier, Christyves
name: Genty, Frédéric
name: Jacquet, Joel
name: Fressengeas, Nicolas
Publisher: name: arXiv
Year: 2011
Subjects: subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: A high reflectivity and polarization selective high contrast grating mirror has been designed with the use of an automated optimization algorithm. Through a precise study of the tolerance of the different lengths of the structure, the robustness with respect to the fabrication errors has been enhanced to high tolerance values between 5 % and 210 %. This adjustment of the dimensions of the structure leads to a 250 nm large bandwidth mirror well adapted for a VCSEL application at λ= 2.65 $μ$m and can easily be scaled for other wavelengths.
description: The final publication is available at http://www.sciencedirect.com/science/article/pii/S0030399211002672\#FCANote
Reconciling cyanobacterial fixed-nitrogen distributions and transport experiments with quantitative modelling
Creators: name: Brown, Aidan I.
name: Rutenberg, Andrew D.
Publisher: name: arXiv
Year: 2011
Subjects: subject: Biological Physics (physics.bio-ph)
subject: Cell Behavior (q-bio.CB)
subject: FOS: Physical sciences
subject: FOS: Biological sciences

description: Filamentous cyanobacteria growing in media with insufficient fixed nitrogen differentiate some cells into heterocysts, which fix nitrogen for the remaining vegetative cells. Transport studies have shown both periplasmic and cytoplasmic connections between cells that could transport fixed-nitrogen along the filament. Two experiments have imaged fixed-nitrogen distributions along filaments. In 1974,Wolk et al found a peaked concentration of fixed-nitrogen at heterocysts using autoradiographic techniques. In contrast, in 2007, Popa et al used nanoSIMS to show large dips at the location of heterocysts, with a variable but approximately level distribution between them. With an integrated model of fixed-nitrogen transport and cell growth, we recover the results of both Wolk et al and of Popa et al using the same model parameters. To do this, we account for immobile incorporated fixed-nitrogen and for the differing durations of labeled nitrogen fixation that occurred in the two experiments. The variations seen by Popa et al are consistent with the effects of cell-by-cell variations of growth rates, and mask diffusive gradients. We are unable to rule out a significant amount of periplasmic fN transport.
description: This is an author-created, un-copyedited version of an article accepted for publication in Physical Biology. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The definitive publisher-authenticated version will be available online
Half-Vortex Unbinding and Ising Transition in Constrained Superfluids
Creators: name: Bonnes, Lars
name: Wessel, Stefan
Publisher: name: arXiv
Year: 2012
Subjects: subject: Quantum Gases (cond-mat.quant-gas)
subject: FOS: Physical sciences

description: We analyze the thermodynamics of the atomic and (nematic) pair superfluids appearing in the attractive two-dimensional Bose-Hubbard model with a three-body hard-core constraint that has been derived as an effective model for cold atoms subject to strong three-body losses in optical lattices. We show that the thermal disintegration of the pair superfluidity is governed by the proliferation of fractional half-vortices leading to a Berezinskii-Kosterlitz-Thousless transition with unusual jump in the helicity modulus. In addition to the (conventional) Berezinskii-Kosterlitz-Thousless transition out of the atomic superfluid, we furthermore identify a direct thermal phase transition separating the pair and the atomic superfluid phases, and show that this transition is continuous with critical scaling exponents consistent with those of the two-dimensional Ising universality class. We exhibit a direct connection between the partial loss of quasi long-range order at the Ising transition between the two superfluids and the parity selection in the atomic winding number fluctuations that distinguish the atomic from the pair superfluid.
description: 15 pages, 9 figures
Color superconductivity on the lattice -- analytic predictions from QCD in a small box
Creators: name: Yokota, Takeru
name: Ito, Yuta
name: Matsufuru, Hideo
name: Namekawa, Yusuke
name: Nishimura, Jun
name: Tsuchiya, Asato
name: Tsutsui, Shoichiro
Publisher: name: arXiv
Year: 2023
Subjects: subject: High Energy Physics - Lattice (hep-lat)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We investigate color superconductivity on the lattice using the gap equation for the Cooper pair condensate. The weak coupling analysis is justified by choosing the physical size of the lattice to be smaller than the QCD scale, while keeping the aspect ratio of the lattice small enough to suppress thermal excitations. In the vicinity of the critical coupling constant that separates the superconducting phase and the normal phase, the gap equation can be linearized, and by solving the corresponding eigenvalue problem, we obtain the critical point and the Cooper pair condensate without assuming its explicit form. The momentum components of the condensate suggest spatially isotropic s-wave superconductivity with Cooper pairs formed by quarks near the Fermi surface. The chiral symmetry in the massless limit is spontaneously broken by the Cooper pair condensate, which turns out to be dominated by the scalar and the pseudo-scalar components. Our results provide useful predictions, in particular, for future lattice simulations based on methods to overcome the sign problem such as the complex Langevin method.
description: 30 pages, 15 figures, 1 table, v2: A.3 modified, Ref. [57] added
Mechanism of Stepped Leaders in a Simple Discharge Model
Creators: name: Sakaguchi, Hidetsugu
name: Kourkouss, Sahim M.
Publisher: name: arXiv
Year: 2011
Subjects: subject: Plasma Physics (physics.plasm-ph)
subject: Pattern Formation and Solitons (nlin.PS)
subject: FOS: Physical sciences

description: We construct a one-dimensional model for the stepped leader in the filamental discharge by simplifying an electric-circuit model of discharge. We find that the leader of the discharge moves stepwise by direct numerical simulations, and then we try to understand the mechanism of the stepwise motion by reducing the spatially extended system to the dynamics of the tip position of the discharge.
description: 4 figures
Generalized parton distributions of sea quark at zero skewness in the light-cone Model
Creators: name: Luan, Xiaoyan
name: Lu, Zhun
Publisher: name: arXiv
Year: 2023
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: We study the chiral-even generalized parton distributions (GPDs) of $\bar{u}$ and $\bar{d}$ quarks at zero skewness using the overlap representation within the light cone formalism. The GPDs of $\bar{u}$ and $\bar{d}$ quarks can be expressed as the convolution of the light cone wave functions which are obtained from the baryon-meson fluctuation model in terms of the $|q\bar{q}B\rangle$ Fock states. We present the numerical results for $H^{\bar{u}/P}(x,ξ,Δ^2)$, $H^{\bar{d}/P}(x,ξ,Δ^2)$, $E^{\bar{u}/P}(x,ξ,Δ^2)$ and $E^{\bar{d}/P}(x,ξ,Δ^2)$. We apply the model resulting GPDs to calculate the orbital angular momentum of the $\bar{u}$ and $\bar{d}$ quarks, showing that $L^{\bar{u}/P}$, $L^{\bar{d}/P}$ are positive and $L^{\bar{u}/P}$ is smaller than $L^{\bar{d}/P}$. The sea quark OAM distributions in the impact parameter space $L_{\bar{q}}(x,\boldsymbol{b_T})$ are also calculated.
description: 8 pages, 5 figures
Weeber, K.-W. (2019): Botschaften aus dem Alten Rom – Die besten Graffiti der Antike
Creators: name: Schmude, Michael P.
Publisher: name: Forum Classicum
Year: 2020

description: Rezension zu: Weeber, K.-W. (2019): Botschaften aus dem Alten Rom – Die besten Graffiti der Antike, Freiburg i. Br., Herder, 192 S. (ISBN 978-3-451-06827-0)
description: Forum Classicum, Nr. 3 (2020): Forum Classicum
Swoboda, Erich, Carnuntum : Seine Geschichte und seine Denkmäler
Creators: name: Moreau, Jacques
Publisher: name: Trierer Zeitschrift - Archäologie und Kunst des Trierer Landes und seiner Nachbargebiete
Year: 2020

description: Rezension zu: Swoboda, Erich, Carnuntum : Seine Geschichte und seine Denkmäler. Wien, 1953. 258 S., 20 Abb., 52 Taf. - (Römische Forschungen in Niederösterreich ; 1)
description: Trierer Zeitschrift - Archäologie und Kunst des Trierer Landes und seiner Nachbargebiete, Bd. 22 Nr. 1/2 (1953): Trierer Zeitschrift : für Geschichte und Kunst des Trierer Landes und seiner Nachbargebiete
Band structures and contact points in phosphorene superlattice
Creators: name: Seffadi, Jilali
name: Redouani, Ilham
name: Zahidi, Youness
name: Jellal, Ahmed
Publisher: name: arXiv
Year: 2023
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: We study the band structures and the associated contact points for a phosphorene superlattice made up of two periodic areas. We use the boundary conditions to extract an equation describing the dispersion relation after obtaining the eigen-wavefunctions. We show that energy transforms into linear behavior near contact points, and fermions move at different speeds along $x$- and $y$- directions. It was discovered that the periodic potential caused additional Dirac points, which we located in $k$-space by establishing their positions. We demonstrate that the barrier height and width can be used to adjust the energy gap and modify the contact points. It might be that our findings will be useful in the development of phosphorene-based electronic devices.
description: 13 pages, 11 figures
Running a distributed virtual observatory: US Virtual Astronomical Observatory operations
Creators: name: McGlynn, Thomas A.
name: Hanisch, Robert J.
name: Berriman, G. Bruce
name: Thakar, Aniruddha R.
Publisher: name: arXiv
Year: 2012
Subjects: subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: FOS: Physical sciences

description: Operation of the US Virtual Astronomical Observatory shares some issues with modern physical observatories, e.g., intimidating data volumes and rapid technological change, and must also address unique concerns like the lack of direct control of the underlying and scattered data resources, and the distributed nature of the observatory itself. In this paper we discuss how the VAO has addressed these challenges to provide the astronomical community with a coherent set of science-enabling tools and services. The distributed nature of our virtual observatory-with data and personnel spanning geographic, institutional and regime boundaries-is simultaneously a major operational headache and the primary science motivation for the VAO. Most astronomy today uses data from many resources. Facilitation of matching heterogeneous datasets is a fundamental reason for the virtual observatory. Key aspects of our approach include continuous monitoring and validation of VAO and VO services and the datasets provided by the community, monitoring of user requests to optimize access, caching for large datasets, and providing distributed storage services that allow user to collect results near large data repositories. Some elements are now fully implemented, while others are planned for subsequent years. The distributed nature of the VAO requires careful attention to what can be a straightforward operation at a conventional observatory, e.g., the organization of the web site or the collection and combined analysis of logs. Many of these strategies use and extend protocols developed by the international virtual observatory community.
description: 7 pages with 2 figures included within PDF
Microsecond Isomer at the N=20 Island of Shape Inversion Observed at FRIB
Creators: name: Gray, T. J.
name: Allmond, J. M.
name: Xu, Z.
name: King, T. T.
name: Lubna, R. S.
name: Crawford, H. L.
name: Tripathi, V.
name: Crider, B. P.
name: Grzywacz, R.
name: Liddick, S. N.
name: Macchiavelli, A. O.
name: Miyagi, T.
name: Poves, A.
name: Andalib, A.
name: Argo, E.
name: Benetti, C.
name: Bhattacharya, S.
name: Campbell, C. M.
name: Carpenter, M. P.
name: Chan, J.
name: Chester, A.
name: Christie, J.
name: Clark, B. R.
name: Cox, I.
name: Doetsch, A. A.
name: Dopfer, J.
name: Duarte, J. G.
name: Fallon, P.
name: Frotscher, A.
name: Gaballah, T.
name: Harke, J. T.
name: Heideman, J.
name: Huegen, H.
name: Holt, J. D.
name: Jain, R.
name: Kitamura, N.
name: Kolos, K.
name: Kondev, F. G.
name: Laminack, A.
name: Longfellow, B.
name: Luitel, S.
name: Madurga, M.
name: Mahajan, R.
name: Mogannam, M. J.
name: Morse, C.
name: Neupane, S.
name: Nowicki, A.
name: Ogunbeku, T. H.
name: Ong, W. -J.
name: Porzio, C.
name: Prokop, C. J.
name: Rasco, B. C.
name: Ronning, E. K.
name: Rubino, E.
name: Ruland, T. J.
name: Rykaczewski, K. P.
name: Schaedig, L.
name: Seweryniak, D.
name: Siegl, K.
name: Singh, M.
name: Stuchbery, A. E.
name: Tabor, S. L.
name: Tang, T. L.
name: Wheeler, T.
name: Winger, J. A.
name: Wood, J. L.
Publisher: name: arXiv
Year: 2023
Subjects: subject: Nuclear Experiment (nucl-ex)
subject: FOS: Physical sciences

description: Excited-state spectroscopy from the first Facility for Rare Isotope Beams (FRIB) experiment is reported. A 24(2)-$μ$s isomer was observed with the FRIB Decay Station initiator (FDSi) through a cascade of 224- and 401-keV $γ$ rays in coincidence with $^{32}\textrm{Na}$ nuclei. This is the only known microsecond isomer ($1{\text{ }μ\text{s}}\leq T_{1/2} < 1\text{ ms}$) in the region. This nucleus is at the heart of the $N=20$ island of shape inversion and is at the crossroads of spherical shell-model, deformed shell-model, and ab initio theories. It can be represented as the coupling of a proton hole and neutron particle to $^{32}\textrm{Mg}$, $^{32}\textrm{Mg}+π^{-1} + ν^{+1}$. This odd-odd coupling and isomer formation provides a sensitive measure of the underlying shape degrees of freedom of $^{32}\textrm{Mg}$, where the onset of spherical-to-deformed shape inversion begins with a low-lying deformed $2^+$ state at 885 keV and a low-lying shape-coexisting $0_2^+$ state at 1058 keV. We suggest two possible explanations for the 625-keV isomer in $^{32}$Na: a $6^-$ spherical shape isomer that decays by $E2$ or a $0^+$ deformed spin isomer that decays by $M2$. The present results and calculations are most consistent with the latter, indicating that the low-lying states are dominated by deformation.
description: 7 pages, 5 figures, accepted by Physical Review Letters
Evidence on the Origin of Ergospheric Disk Field Line Topology in Simulations of Black Hole Accretion
Creators: name: Punsly, Brian
Publisher: name: arXiv
Year: 2011
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: This Letter investigates the origin of the asymmetric magnetic field line geometry in the ergospheric disk (and the corresponding asymmetric powerful jet) in 3-D perfect magnetohydrodynamic (MHD) numerical simulations of a rapidly rotating black hole accretion system reported in \citet{pun10}. Understanding, why and how these unexpected asymmetric structures form is of practical interest because an ergospheric disk jet can boost the black hole driven jet power many-fold possibly resolving a fundamental disconnect between the energy flux estimates of powerful quasar jets and simulated jet power \citep{pun11}. The new 3-D simulations of \citet{bec09} that were run with basically the same code that was used in the simulation discussed in \citet{pun10} describe the "coronal mechanism" of accreting poliodal magnetic flux towards the event horizon. It was determined that reconnection in the inner accretion disk is a "necessary" component for this process. The coronal mechanism seems to naturally explain the asymmetric ergospheric disk field lines that were seen in the simulations. Using examples from the literature, it is discussed how apparently small changes in the reconnection geometry and rates can make enormous changes in the magnetospheric flux distribution and the resultant black hole driven jet power in a numerical simulation. Unfortunately, reconnection is a consequence of numerical diffusion and not a detailed (yet to be fully understood) physical mechanism in the existing suite of perfect MHD based numerical simulations. The implication is that there is presently great uncertainty in the flux distribution of astrophysical black hole magnetospheres and the resultant jet power.
description: To appear in MNRAS Letters
Die Treverer zwischen Germanen und Kelten
Creators: name: Jungandreas, Wolfgang
Publisher: name: Trierer Zeitschrift - Archäologie und Kunst des Trierer Landes und seiner Nachbargebiete
Year: 2020

description: Trierer Zeitschrift - Archäologie und Kunst des Trierer Landes und seiner Nachbargebiete, Bd. 22 Nr. 1/2 (1953): Trierer Zeitschrift : für Geschichte und Kunst des Trierer Landes und seiner Nachbargebiete
Quantum correlations by four-wave mixing in an atomic vapor in a non-amplifying regime: a quantum beam splitter for photons
Creators: name: Glorieux, Quentin
name: Guidoni, Luca
name: Guibal, Samuel
name: Likforman, Jean-Pierre
name: Coudreau, Thomas
Publisher: name: arXiv
Year: 2011
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We study the generation of intensity quantum correlations using four-wave mixing in a rubidium vapor. The absence of cavity in these experiments allows to deal with several spatial modes simultaneously. In the standard, amplifying, configuration, we measure relative intensity squeezing up to 9.2 dB below the standard quantum limit. We also theoretically identify and experimentally demonstrate an original regime where, despite no overall amplification, quantum correlations are generated. In this regime a four-wave mixing set-up can therefore play the role of a photonic beam splitter with non--classical properties, i.e. a device that splits a coherent state input into two quantum correlated beams.
description: 5 pages, 4 figures; http://link.aps.org/doi/10.1103/PhysRevA.84.053826
Nonlocal continuum shell models for torsion of single-walled carbon nanotubes
Creators: name: Khademolhosseini, Farzad
Publisher: name: University of British Columbia
Year: 2009

description: Carbon nanotubes (CNTs) have attracted much attention from scientists and engineers because of their relevance to a wide range of applications. Various approaches have been used for the characterization of CNT properties, among which continuum modeling has generated much interest due to computational efficiency. However, at the nanoscale the dimensions of a system are comparable to the inter-atomic or inter-molecular spacing of that system, and the material cannot be modeled as a continuum. This is known as the “size-effect”. To overcome the limitations of classical continuum mechanics, modified continuum models have been proposed, among which models based on the concept of nonlocal elasticity have proven effective in quantifying the size-dependent mechanical response of CNTs. This thesis investigates the “small-size” effects in the torsional response of single walled carbon nanotubes (SWCNTs) by developing a modified nonlocal continuum shell model for their torsion. The purpose is to facilitate the design of devices based on CNT torsion by providing a simple, accurate and efficient continuum model that can predict the torsional buckling loads, the frequency of torsional vibrations and the propagation speed of torsional waves. To this end, Eringen’s equations of nonlocal elasticity are incorporated into the classical models for torsion of cylindrical shells given by Timoshenko and Donnell. In contrast to the classical models, the nonlocal model developed here predicts non-dimensional buckling loads that depend on the values of certain geometric parameters of the CNT, allowing for the inclusion of size-effects. In the case of torsional vibrations and propagation of torsional waves, the classical and nonlocal models predict non-dispersive and dispersive behavior, respectively. Molecular dynamics simulations of torsional buckling, axial buckling and torsional vibration of various SWCNTs are also performed, the results of which are compared with the classical and nonlocal models and used to extract consistent values of the nonlocal elasticity constant. Interestingly, the nonlocal elasticity constant depends on the existence of circumferential and/or longitudinal modes in the deformed shape of the CNT. In all loading cases the superiority of the nonlocal model over the classical elasticity model in predicting the size-dependent mechanical response of SWCNTs is established.
Optical spectroscopy of Be stars: peak separation of Balmer emission lines
Creators: name: Zamanov, R. K.
name: Stoyanov, K. A.
name: Stefanov, S. Y.
name: Bode, M. F.
name: Minev, M. S.
Publisher: name: arXiv
Year: 2023
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: The Be stars display variable optical emission lines originating in the circumstellar disc. Here we analyse high resolution spectroscopic observations of Be stars and the distance between the peaks of H-alpha, H-beta, and H-gamma emission lines ($ΔV_α$, $ΔV_β$, and $ΔV_γ$ respectively). Combining published data, spectra from the ELODIE archive (obtained in the period 1998 -- 2003) and Rozhen spectra (obtained 2015 -- 2023) of 93 Be stars, we find a set of relations connecting $ΔV_α$, $ΔV_β$ and $ΔV_γ$. They are effective for $30 \le ΔV_α\le 500$ km s$^{-1}$, $80 \le ΔV_β\le 600$ km s$^{-1}$, and $40 \le ΔV_γ\le 300$ km s$^{-1}$. The new equations are in the form $y=ax + b$ and are valid for a wider velocity range than in previous studies.
description: Astronomische Nachrichten (accepted)
Central Powering of the Largest Lyman-alpha Nebula is Revealed by Polarized Radiation
Creators: name: Hayes, Matthew
name: Scarlata, Claudia
name: Siana, Brian
Publisher: name: arXiv
Year: 2011
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: High-redshift Lyman-alpha blobs are extended, luminous, but rare structures that appear to be associated with the highest peaks in the matter density of the Universe. Their energy output and morphology are similar to powerful radio galaxies, but the source of the luminosity is unclear. Some blobs are associated with ultraviolet or infrared bright galaxies, suggesting an extreme starburst event or accretion onto a central black hole. Another possibility is gas that is shock excited by supernovae. However some blobs are not associated with galaxies, and may instead be heated by gas falling into a dark matter halo. The polarization of the Ly-alpha emission can in principle distinguish between these options, but a previous attempt to detect this signature returned a null detection. Here we report on the detection of polarized Ly-alpha from the blob LAB1. Although the central region shows no measurable polarization, the polarized fraction (P) increases to ~20 per cent at a radius of 45 kpc, forming an almost complete polarized ring. The detection of polarized radiation is inconsistent with the in situ production of Ly-alpha photons, and we conclude that they must have been produced in the galaxies hosted within the nebula, and re-scattered by neutral hydrogen.
description: Published in the August 18 issue of Nature. 1750 words, 3 figures, and full Supplementary Information. Version has not undergone proofing. Reduced and processed data products are available here: http://obswww.unige.ch/people/matthew.hayes/LymanAlpha/LabPol/
A structure-preserving integrator for incompressible finite elastodynamics based on a grad-div stabilized mixed formulation with particular emphasis on stretch-based material models
Creators: name: Guan, Jiashen
name: Yuan, Hongyan
name: Liu, Ju
Publisher: name: arXiv
Year: 2023
Subjects: subject: Numerical Analysis (math.NA)
subject: FOS: Mathematics

description: We present a structure-preserving scheme based on a recently-proposed mixed formulation for incompressible hyperelasticity formulated in principal stretches. Although there exist Hamiltonians introduced for quasi-incompressible elastodynamics based on different variational formulations, the one in the fully incompressible regime has yet been identified in the literature. The adopted mixed formulation naturally provides a new Hamiltonian for fully incompressible elastodynamics. Invoking the discrete gradient formula, we are able to design fully-discrete schemes that preserve the Hamiltonian and momenta. The scaled mid-point formula, another popular option for constructing algorithmic stresses, is analyzed and demonstrated to be non-robust numerically. The generalized Taylor-Hood element based on the spline technology conveniently provides a higher-order, robust, and inf-sup stable spatial discretization option for finite strain analysis. To enhance the element performance in volume conservation, the grad-div stabilization, a technique initially developed in computational fluid dynamics, is introduced here for elastodynamics. It is shown that the stabilization term does not impose additional restrictions for the algorithmic stress to respect the invariants, leading to an energy-decaying and momentum-conserving fully discrete scheme. A set of numerical examples is provided to justify the claimed properties. The grad-div stabilization is found to enhance the discrete mass conservation effectively. Furthermore, in contrast to conventional algorithms based on Cardano's formula and perturbation techniques, the spectral decomposition algorithm developed by Scherzinger and Dohrmann is robust and accurate to ensure the discrete conservation laws and is thus recommended for stretch-based material modeling.
Constraining AGN Torus Sizes with Optical and Mid-Infrared Ensemble Structure Functions
Creators: name: Li, Junyao
name: Shen, Yue
Publisher: name: arXiv
Year: 2023
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We propose a new method to constrain the size of the dusty torus in broad-line active galactic nuclei (AGNs) using optical and mid-infrared (MIR) ensemble structure functions (SFs). Because of the geometric dilution of the torus, the MIR response to optical continuum variations has suppressed variability with respect to the optical that depends on the geometry (e.g., size, orientation, opening angle) of the torus. More extended tori have steeper MIR SFs with respect to the optical SFs. We demonstrate the feasibility of this SF approach using simulated AGN light curves and a geometric torus model. While it is difficult to use SFs to constrain the orientation and opening angle due to insensitivity of the SF on these parameters, the size of the torus can be well determined. Applying this method to the ensemble SFs measured for 587 SDSS quasars, we measure a torus $R-L$ relation of ${\rm log}\,R_{\rm eff}\, {(\rm pc)} = 0.51_{-0.04}^{+0.04} \times {\rm log}\,(L_{\rm bol}/10^{46}\,\rm erg\,s^{-1}) -0.38_{-0.01}^{+0.01}$ in the WISE $W1$ band, and sizes $\sim1.4$ times larger in the $W2$ band, which are in good agreement with dust reverberation mapping measurements. Compared with the reverberation mapping technique, the SF method is much less demanding in data quality and can be applied to any optical+MIR light curves for which a lag measurement may not be possible, as long as the variability process and torus structure are stationary. While this SF method does not extract all information contained in the light curves (i.e., the transfer function), it provides an intuitive interpretation for the observed trends of AGN MIR SFs compared with optical SFs.
description: 16 pages, 10 figures, accepted for publication in ApJ
T4 DNA condensation in water-alcohol media
Creators: name: Gallyamov, M. O.
name: Pyshkina, O. A.
name: Sergeyev, V. G.
name: Yaminsky, I. V.
Publisher: name: arXiv
Year: 2011
Subjects: subject: Soft Condensed Matter (cond-mat.soft)
subject: FOS: Physical sciences

description: The process of compaction of high molecular weight DNA T4 is investigated directly in a AFM liquid cell. The AFM-images of globules formed by DNA molecules in the result of compaction in water-alcohol environments at high izopropanol concentration (80%) are received; it is found that at intermediate concentration of izopropanol (40-50%) the DNA molecules form partially compacted formations in which the separate coils of macromolecules twist in toroidal structures. It is shown using the technique of deconvolution of the AFM-images that the globule include only one closely packed DNA molecule. The model of DNA packing is proposed on the basis of AFM experiment.
description: in Russian
Jet Production Rates in Association with W and Z Bosons in pp Collisions at sqrt(s) = 7 TeV
Creators: name: CMS Collaboration
Publisher: name: arXiv
Year: 2011
Subjects: subject: High Energy Physics - Experiment (hep-ex)
subject: FOS: Physical sciences

description: Measurements of jet production rates in association with W and Z bosons for jet transverse momenta above 30 GeV are reported, using a sample of proton-proton collision events recorded by CMS at sqrt(s) = 7 TeV, corresponding to an integrated luminosity of 36 inverse picobarns. The study includes the measurement of the normalized inclusive rates of jets sigma(V + >= n jets)/sigma(V), where V represents either a W or a Z. In addition, the ratio of W to Z cross sections and the W charge asymmetry as a function of the number of associated jets are measured. A test of Berends--Giele scaling at sqrt(s) = 7 TeV is also presented. The measurements provide a stringent test of perturbative-QCD calculations and are sensitive to the possible presence of new physics. The results are in agreement with the predictions of a simulation that uses explicit matrix element calculations for final states with jets.
Probing dark fluids and modified gravity with gravitational lensing
Creators: name: Perivolaropoulos, L.
name: Antoniou, I.
name: Papadopoulos, D.
Publisher: name: arXiv
Year: 2023
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: Space Physics (physics.space-ph)
subject: FOS: Physical sciences

description: We generalize the Rindler-Ishak (2007) result for the lensing deflection angle in a SdS spacetime, to the case of a general spherically symmetric fluid beyond the cosmological constant. We thus derive an analytic expression to first post-Newtonian order for the lensing deflection angle in a general static spherically symmetric metric of the form $ ds^2 = f(r)dt^{2} -\frac{dr^{2}}{f(r)}-r^{2}(dθ^2 +\sin ^2 θdϕ^2)$ with $f(r) = 1 - \frac{2m}{r}-\sum_{i} b_i\; r_0^{-q_i}\; \left( \frac{r_0}{r}\right)^{q_i}$ where $r_0$ is the lensing impact parameter, $b_i\ll r_0^{q_i}$, $m$ is the mass of the lens and $q_i$ are real arbitrary constants related to the properties of the fluid that surrounds the lens or to modified gravity. This is a generalization of the well known Kiselev black hole metric. The approximate analytic expression of the deflection angle is verified by an exact numerical derivation and in special cases it reduces to results of previous studies. The density and pressure of the spherically symmetric fluid that induces this metric is derived in terms of the constants $b_i$. The Kiselev case of a Schwarzschild metric perturbed by a general spherically symmetric dark fluid (eg vacuum energy) is studied in some detail and consistency with the special case of Rindler Ishak result is found for the case of a cosmological constant background. Observational data of the Einstein radii from distant clusters of galaxies lead to observational constraints on the constants $b_i$ and through them on the density and pressure of dark fluids, field theories or modified gravity theories that could induce this metric.
description: 9 pages, 4 Figures, 2 Tables. Published in MNRAS. The Mathematica files used for the construction of Fig. 2 and 3 may be downloaded from https://github.com/leandros11/lensing1
The deformation-stability fundamental length and deviations from c
Creators: name: Mendes, R. Vilela
Publisher: name: arXiv
Year: 2011
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: The existence of a fundamental length (or fundamental time) has been conjectured in many contexts. However, the "stability of physical theories principle" seems to be the one that provides, through the tools of algebraic deformation theory, an unambiguous derivation of the stable structures that Nature might have chosen for its algebraic framework. It is well-known that $1/c$ and $\hbar $ are the deformation parameters that stabilize the Galilean and the Poisson algebra. When the stability principle is applied to the Poincaré-Heisenberg algebra, two deformation parameters emerge which define two length (or time) scales. In addition there are, for each of them, a plus or minus sign possibility in the relevant commutators. One of the deformation length scales, related to non-commutativity of momenta, is probably related to the Planck length scale but the other might be much larger. In this paper this is used as a working hypothesis to compute deviations from $c$ in speed measurements of massless wave packets.
description: 12 pages Latex