cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
The nature of sub-millimetre galaxies I: A comparison of AGN and star-forming galaxy SED fits
Creators: name: Shanks, T.
name: Ansarinejad, B.
name: Bielby, R. M.
name: Heywood, I.
name: Metcalfe, N.
name: Wang, L.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: High redshift sub-millimetre galaxies (SMGs) are usually assumed to be powered by star-formation. However, it has been clear for some time that $>$20% of such sources brighter than $\approx3$mJy host quasars. Here we analyse a complete sample of 12 sub-mm LABOCA/ALMA 870 $μ$m sources in the centre of the William Herschel Deep Field (WHDF) with multi-wavelength data available from the X-ray to the radio bands. Previously, two sources were identified as X-ray absorbed quasars at $z=1.32$ and $z=2.12$. By comparing their spectral energy distributions (SEDs) with unabsorbed quasars in the same field, we confirm that they are dust reddened although at a level significantly lower than implied by their X-ray absorption. Then we compare the SED's of all the sources to dust-reddened AGN and star-forming galaxy models. This optical/NIR comparison combined with Spitzer MIR colours and faint Chandra X-ray detections shows that 7/12 SMGs are best fitted with an obscured quasarmodel, a further 3/12 show no preference between AGN and star-forming templates, leaving only a $z=0.046$ spiral galaxy and one unidentified source. So in our complete sample, the majority (10/12) of bright SMGs are at least as likely to fit an AGN as a star-forming galaxy template, although no claim is made to rule out the latter as SMG power sources. We then suggest modifications to a previous SMG number count model and conclude that obscured AGN in SMGs may still provide the dominant contribution to both the hard X-ray and sub-millimetre backgrounds.
description: 22 pages, 11 Figures and 6 Tables. MNRAS accepted
Equatorial and related non-equilibrium states in magnetization dynamics of ferromagnets: Generalization of Suhl's spin-wave instabilities
Creators: name: Kosaka, C.
name: Nakamura, K.
name: Murugesh, S.
name: Lakshmanan, M.
Publisher: name: arXiv
Year: 2005
Subjects: subject: Chaotic Dynamics (nlin.CD)
subject: Pattern Formation and Solitons (nlin.PS)
subject: FOS: Physical sciences

description: We investigate the nonlinear dynamics underlying the evolution of a 2-D nanoscale ferromagnetic film with uniaxial anisotropy in the presence of perpendicular pumping. Considering the associated Landau-Lifshitz spin evolution equation with Gilbert damping together with Maxwell equation for the demagnetization field, we study the dynamics in terms of the stereographic variable. We identify several new fixed points for suitable choice of external field in a rotating frame of reference. In particular, we identify explicit equatorial and related fixed points of the spin vector in the plane transverse to the anisotropy axis when the pumping frequency coincides with the amplitude of the static parallel field. We then study the linear stability of these novel fixed points under homogeneous and spin wave perturbations and obtain a generalized Suhl's instability criterion, giving the condition for exponential growth of P-modes under spin wave perturbations. Two parameter phase diagrams (in terms of amplitudes of static parallel and oscillatory perpendicular magnetic fields) for stability are obtained, which differ qualitatively from those for the conventional ferromagnetic resonance near thermal equilibrium and are amenable to experimental tests.
description: 23 pages, 5 figures, To appear in Physica D
Cairo et al Supplementary materials : Identifying pesticide mixtures at country-wide scale
Creators: name: Cairo, Milena
name: Monnet, Anne-Christine
name: Robin, Stéphane
name: Porcher, Emmanuelle
name: Fontaine, Colin
Publisher: name: Zenodo
Year: 2023

description: Supplementary materials : Identifying pesticide mixtures at country-wide scale

- Supplementary figures

- 3 data sets

- 2 R scripts

- 1 text file : README
A detailed spectral and morphological study of the gamma-ray supernova remnant RX J1713.7-3946 with H.E.S.S
Creators: name: The HESS Collaboration
name: Aharonian, F.
Publisher: name: arXiv
Year: 2005
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We present results from deep observations of the Galactic shell-type supernova remnant (SNR) RX J1713.7-3946 (also known as G347.3-0.5) conducted with the complete H.E.S.S. array in 2004. Detailed morphological and spatially resolved spectral studies reveal the very-high-energy (VHE -- Energies E > 100 GeV) gamma-ray aspects of this object with unprecedented precision. Since this is the first in-depth analysis of an extended VHE gamma-ray source, we present a thorough discussion of our methodology and investigations of possible sources of systematic errors. Gamma rays are detected throughout the whole SNR. The emission is found to resemble a shell structure with increased fluxes from the western and northwestern parts. The differential gamma-ray spectrum of the whole SNR is measured over more than two orders of magnitude, from 190 GeV to 40 TeV, and is rather hard with indications for a deviation from a pure power law at high energies. Spectra have also been determined for spatially separated regions of RX J1713.7-3946. The flux values vary by more than a factor of two, but no significant change in spectral shape is found. There is a striking correlation between the X-ray and the gamma-ray image. Radial profiles in both wavelength regimes reveal the same shape almost everywhere in the region of the SNR. The VHE gamma-ray emission of RX J1713.7-3946 is phenomenologically discussed for two scenarios, one where the gamma rays are produced by VHE electrons via Inverse Compton scattering and one where the gamma rays are due to neutral pion decay from proton-proton interactions. In conjunction with multi-wavelength considerations, the latter case is favoured. However, no decisive conclusions can yet be drawn regarding the parent particle population dominantly responsible for the gamma-ray emission from RX J1713.7-3946.
description: 20 pages, 20 figures (low resolution), Accepted for publication in A&A - Revision 1: Added reference to Section 4.2. Added sentence to acknowledgements
Theoretical model for the evolution of the linguistic diversity
Creators: name: de Oliveira, Viviane M.
name: Gomes, M. A. F.
name: Tsang, I. R.
Publisher: name: arXiv
Year: 2005
Subjects: subject: Physics and Society (physics.soc-ph)
subject: FOS: Physical sciences

description: Here we describe how some important scaling laws observed in the distribution of languages on Earth can emerge from a simple computer simulation. The proposed language dynamics includes processes of selective geographic colonization, linguistic anomalous diffusion and mutation, and interaction among populations that occupy different regions. It is found that the dependence of the linguistic diversity on the area after colonization displays two power law regimes, both described by critical exponents which are dependent on the mutation probability. Most importantly for the future prospect of world's population, our results show that the linguistic diversity always decrease to an asymptotic very small value if large areas and sufficiently long times of interaction among populations are considered.
description: 13 pages, 6 figures
Cairo et al Supplementary materials : Identifying pesticide mixtures at country-wide scale
Creators: name: Cairo, Milena
name: Monnet, Anne-Christine
name: Robin, Stéphane
name: Porcher, Emmanuelle
name: Fontaine, Colin
Publisher: name: Zenodo
Year: 2024

description: Supplementary materials : Identifying pesticide mixtures at country-wide scale

- Supplementary figures

- 3 data sets

- 2 R scripts

- 1 text file : README
Spin-density-wave order in cuprates
Creators: name: De Prato, Martino
name: Pelissetto, Andrea
name: Vicari, Ettore
Publisher: name: arXiv
Year: 2006
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Superconductivity (cond-mat.supr-con)
subject: High Energy Physics - Lattice (hep-lat)
subject: FOS: Physical sciences

description: We study the nature of the two-dimensional quantum critical point separating two phases with and without long-range spin-density-wave order, which has been recently observed in cuprate superconductors. We consider the Landau-Ginzburg-Wilson Hamiltonian associated with the spin-density critical modes, perform a mean-field analysis of the phase diagram, and study the corresponding renormalization-group flow in two different perturbative schemes at five and six loops, respectively. The analysis supports the existence of a stable fixed point in the full theory whose basin of attraction includes systems with collinear spin-density-wave order, as observed in experiments. The stable fixed point is characterized by an enlarged O(4)xO(3) symmetry. The continuous transition observed in experiments is expected to belong to this universality class. The corresponding critical exponents are nu = 0.9(2) and eta = 0.15(10).
description: 21 pages
Assessing Viewpoint Diversity in Search Results Using Ranking Fairness Metrics
Creators: name: Draws, Tim
name: Tintarev, Nava
name: Gadiraju, Ujwal
name: Bozzon, Alessandro
name: Timmermans, Benjamin
Publisher: name: arXiv
Year: 2020
Subjects: subject: Information Retrieval (cs.IR)
subject: FOS: Computer and information sciences

description: The way pages are ranked in search results influences whether the users of search engines are exposed to more homogeneous, or rather to more diverse viewpoints. However, this viewpoint diversity is not trivial to assess. In this paper we use existing and novel ranking fairness metrics to evaluate viewpoint diversity in search result rankings. We conduct a controlled simulation study that shows how ranking fairness metrics can be used for viewpoint diversity, how their outcome should be interpreted, and which metric is most suitable depending on the situation. This paper lays out important ground work for future research to measure and assess viewpoint diversity in real search result rankings.
Cairo et al Supplementary materials : Identifying pesticide mixtures at country-wide scale
Creators: name: Cairo, Milena
name: Monnet, Anne-Christine
name: Robin, Stéphane
name: Porcher, Emmanuelle
name: Fontaine, Colin
Publisher: name: Zenodo
Year: 2023

description: Supplementary materials : Identifying pesticide mixtures at country-wide scale - 3 data sets - 2 R scripts - 1 text file : README
Dynamics of the Sixth Painlevé Equation
Creators: name: Inaba, Michi-aki
name: Iwasaki, Katsunori
name: Saito, Masa-Hiko
Publisher: name: arXiv
Year: 2005
Subjects: subject: Algebraic Geometry (math.AG)
subject: Dynamical Systems (math.DS)
subject: FOS: Mathematics
subject: 34M55, 14D20, 33E17, 32G34, 37J35

description: The sixth Painlevé equation is hiding extremely rich geometric structures behind its outward appearance. This article tries to give as a total picture as possible of its dynamical natures, based on the Riemann-Hilbert approach recently developed by the authors, using various techniques from algebraic geometry. A good part of the contents is extended to Garnier systems, while this article is restricted to the original sixth Painlevé equation.
description: 56 pages, 18 figures, reference updated
The application of spectral unmixing and supervised classification remote sensing techniques to Landsat 7 data for detecting arboreal lichen abundance
Creators: name: Norquay, Alan
Publisher: name: University of British Columbia
Year: 2009

description: In British Columbia, mountain caribou (Rangifer tarandus caribou) rely on arboreal lichen as a main source of food during the late winter months. The animals spend a majority of the year at these higher elevations where old growth forests provide a suitable microclimate for the lichen genera Bryoria and, to a lesser extent, Alectoria. Caribou migrate there from lower areas when the snowpack solidifies sufficiently to allow efficient travel, possible by their unique hooves that spread to distribute weight. Forestry operations also have an interest in these old growth stands, and harvesting operations have begun to threaten the continued existence of mountain caribou in British Columbia. Efforts to determine caribou habitat, and the extent of that habitat, have been underway for many years. However, there has been an increase in the amount and intensity of research during the past six years, due largely to higher level planning processes that have identified the animals as a priority for inventory research programs. This research was focused on identifying stands of trees that contain arboreal lichen by using remotely - sensed data. While it is known that older stands are required for lichen growth, not all older stands have produced useful quantities of lichen. Since stands containing heavy loadings of arboreal lichen appear different to the naked eye than those with lesser loadings, it is reasonable to assume these differences can be measured with remote sensing techniques. The purpose of this work is to identify these differences using Landsat 7 data. I used a 30-metre pixel resolution Landsat scene collected on August 22 1999. Spectral unmixing, supervised classification and correlation analysis techniques where conducted, but no method was able to distinguish stands by the amount of lichen they contained. The reason this attempt did not succeed is probably due to the pixel size of the data (30 metres) versus the effect small clumps of lichen have on the reflectance recorded for those pixels. If data from a sensor with higher spatial resolution (e.g. IKONOS 4 meter data) where used in future work, the results may be more successful.
Correlations in totally symmetric self-complementary plane partitions
Creators: name: Ayyer, Arvind
name: Chhita, Sunil
Publisher: name: arXiv
Year: 2020
Subjects: subject: Probability (math.PR)
subject: Mathematical Physics (math-ph)
subject: Combinatorics (math.CO)
subject: FOS: Mathematics
subject: FOS: Physical sciences
subject: 82B20, 60K35, 05C70, 05A17

description: Totally symmetric self-complementary plane partitions (TSSCPPs) are boxed plane partitions with the maximum possible symmetry. We use the well-known representation of TSSCPPs as a dimer model on a honeycomb graph enclosed in one-twelfth of a hexagon with free boundary to express them as perfect matchings of a family of non-bipartite planar graphs. Our main result is that the edges of the TSSCPPs form a Pfaffian point process, for which we give explicit formulas for the inverse Kasteleyn matrix. Preliminary analysis of these correlations are then used to give a precise conjecture for the limit shape of TSSCPPs in the scaling limit.
description: 38 pages, 14 figures, minor corrections, final version
Parametric form of QCD travelling waves
Creators: name: Peschanski, R.
Publisher: name: arXiv
Year: 2005
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We derive parametric travelling-wave solutions of non-linear QCD equations. They describe the evolution towards saturation in the geometric scaling region. The method, based on an expansion in the inverse of the wave velocity, leads to a solvable hierarchy of differential equations. A universal parametric form of travelling waves emerges from the first two orders of the expansion.
description: 4 pages, 1 figure
Fast multilevel radiative transfer
Creators: name: Paletou, F.
name: Leger, L.
Publisher: name: arXiv
Year: 2005
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: The vast majority of recent advances in the field of numerical radiative transfer relies on approximate operator methods better known in astrophysics as Accelerated Lambda-Iteration (ALI). A superior class of iterative schemes, in term of rates of convergence, such as Gauss-Seidel and Successive Overrelaxation methods were therefore quite naturally introduced in the field of radiative transfer by Trujillo Bueno & Fabiani Bendicho (1995); it was thoroughly described for the non-LTE two-level atom case. We describe hereafter in details how such methods can be generalized when dealing with non-LTE unpolarised radiation transfer with multilevel atomic models, in monodimensional geometry.
description: 16 pages, 4 figs (1 changed), 2 tables (1 added): to appear in the JQSRT
Renormalizability of non-anticommutative N=(1,1) theories with singlet deformation
Creators: name: Buchbinder, I. L.
name: Ivanov, E. A.
name: Lechtenfeld, O.
name: Samsonov, I. B.
name: Zupnik, B. M.
Publisher: name: arXiv
Year: 2005
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We study the quantum properties of two theories with a non-anticommutative (or nilpotent) chiral singlet deformation of N=(1,1) supersymmetry: the abelian model of a vector gauge multiplet and the model of a gauge multiplet interacting with a neutral hypermultiplet. In spite of the presence of a negative-mass-dimension coupling constant (deformation parameter), both theories are shown to be finite in the sense that the full effective action is one-loop exact and contains finitely many divergent terms, which vanish on-shell. The beta-function for the coupling constant is equal to zero. The divergencies can all be removed off shell by a redefinition of one of the two scalar fields of the gauge multiplet. These notable quantum properties are tightly related to the existence of a Seiberg-Witten-type transformation in both models.
description: 1+31 pages, 2 figures, uses axodraw.sty; v2: a misprint corrected; v3: a reference added; v.4: minor changes in the text, references added, published version
Jet-associated deuteron production in pp collisions at $\sqrt{s}=13$ TeV
Creators: name: ALICE Collaboration
Publisher: name: arXiv
Year: 2020
Subjects: subject: Nuclear Experiment (nucl-ex)
subject: High Energy Physics - Experiment (hep-ex)
subject: FOS: Physical sciences

description: Deuteron production in high-energy collisions is sensitive to the space-time evolution of the collision system, and is typically described by a coalescence mechanism. For the first time, we present results on jet-associated deuteron production in \pp\ collisions at $\sqrt{s}=13$ TeV, providing an opportunity to test the established picture for deuteron production in events with a hard scattering. Using a trigger particle with high transverse-momentum ($p_{\rm T}>5$ GeV/$c$) as a proxy for the presence of a jet at midrapidity, we observe a measurable population of deuterons being produced around the jet proxy. The associated deuteron yield measured in a narrow angular range around the trigger particle differs by 2.4-4.8 standard deviations from the uncorrelated background. The data are described by PYTHIA model calculations featuring baryon coalescence.
description: 18 pages, 3 captioned figures, 2 tables, authors from page 13, published version, figures at http://alice-publications.web.cern.ch/node/6692
Szegő and Widom theorems for finite codimensional subalgebras of a class of uniform algebras
Creators: name: Pfeffer, Douglas T.
name: Jury, Michael T.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Functional Analysis (math.FA)
subject: FOS: Mathematics
subject: 47B35 (Primary), 47A05

description: We establish versions of Szegő's distance formula and Widom's theorem on invertibility of (a family of) Toeplitz operators in a class of finite codimension subalgebras of uniform algebras, obtained by imposing a finite number of linear constraints. Each such algebra is naturally represented on a family of reproducing kernel Hilbert spaces, which play a central role in the proofs.
description: 37 pages, no figures, to appear in the journal of Complex Analysis and Operator Theory (Published online: 05 June 2021)
Twisted Galilean symmetry and the Pauli principle at low energies
Creators: name: Chakraborty, Biswajit
name: Gangopadhyay, Sunandan
name: Hazra, Arindam Ghosh
name: Scholtz, Frederik. G.
Publisher: name: arXiv
Year: 2006
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We show the twisted Galilean invariance of the noncommutative parameter, even in presence of space-time noncommutativity. We then obtain the deformed algebra of the Schrödinger field in configuration and momentum space by studying the action of the twisted Galilean group on the non-relativistic limit of the Klein-Gordon field. Using this deformed algebra we compute the two particle correlation function to study the possible extent to which the previously proposed violation of the Pauli principle may impact at low energies. It is concluded that any possible effect is probably well beyond detection at current energies.
description: 16 pages Latex, 2 figures Some modifications made in the abstract, introduction, typographical errors corrected
Hidden spin-isospin exchange symmetry
Creators: name: Lee, Dean
name: Bogner, Scott
name: Brown, B. Alex
name: Elhatisari, Serdar
name: Epelbaum, Evgeny
name: Hergert, Heiko
name: Hjorth-Jensen, Morten
name: Krebs, Hermann
name: Li, Ning
name: Lu, Bing-Nan
name: Meißner, Ulf-G.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Nuclear Theory (nucl-th)
subject: High Energy Physics - Lattice (hep-lat)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: Nuclear Experiment (nucl-ex)
subject: FOS: Physical sciences

description: The strong interactions among nucleons have an approximate spin-isospin exchange symmetry that arises from the properties of quantum chromodynamics in the limit of many colors, $N_c$. However this large-$N_c$ symmetry is well hidden and reveals itself only when averaging over intrinsic spin orientations. Furthermore, the symmetry is obscured unless the momentum resolution scale is close to an optimal scale that we call $Λ_{{\rm large-}N_c}$. We show that the large-$N_c$ derivation requires a momentum resolution scale of $Λ_{{\rm large-}N_c} \sim 500$ MeV. We derive a set of spin-isospin exchange sum rules and discuss implications for the spectrum of $^{30}$P and applications to nuclear forces, nuclear structure calculations, and three-nucleon interactions.
description: 5 pages (main) + 3 pages (supplemental materials), 1 figure (main) + 4 figures (supplemental materials), final version to appear in Phys. Rev. Lett
Geometry and symmetry in biochemical reaction systems
Creators: name: Mulas, Raffaella
name: Sánchez-García, Rubén J.
name: MacArthur, Ben D.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Combinatorics (math.CO)
subject: Spectral Theory (math.SP)
subject: FOS: Mathematics

description: Complex systems of intracellular biochemical reactions have a central role in regulating cell identities and functions. Biochemical reaction systems are typically studied using the language and tools of graph theory. However, graph representations only describe pairwise interactions between molecular species, and so are not well suited to modelling complex sets of reactions that may involve numerous reactants and/or products. Here we make use of a recently-developed hypergraph theory of chemical reactions that naturally allows for higher-order interactions to explore the geometry and quantify functional redundancy in biochemical reactions systems. Our results constitute a general theory of automorphisms for oriented hypergraphs and describe the effect of automorphism group structure on hypergraph Laplacian spectra.
description: Theory in Biosciences, To appear
Mass and angular momentum of asymptotically AdS or flat solutions in the topologically massive gravity
Creators: name: Olmez, Serkay
name: Sarioglu, Ozgur
name: Tekin, Bayram
Publisher: name: arXiv
Year: 2005
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We study the conserved charges of supersymmetric solutions in the topologically massive gravity theory for both asymptotically flat and constant curvature geometries.
description: REVTEX4, 8 pages, no figures, added 2 references and a few clarifying remarks
title: An iterative approach to sound source localization based on spherical beamforming
Creators: name: Szwajcowski, Adam
name: Makuch, Teresa
name: Celniak, Weronika
Publisher: name: Publishing House of Poznan University of Technology
Year: 2023

description: Vibrations in Physical Systems, 34(2), 2023216-1 - 2023216-12
Yield, sustainable harvest and cultural uses of resin from the copal tree (Protium copal: Burseraceae) in the carmelita community forest concession, Petén, Guatemala
Creators: name: Neels, Sabine
Publisher: name: University of British Columbia
Year: 2009

description: A three-part study was conducted on Protium copal (Burseraceae) in the lowland tropical forests of northern Guatemala with the principle objective of providing preliminary data for the potential exploitation of its resin. Part one investigated the potential resin yield of an area within the Carmelita Community Forest Concession (CCFC), in the department of Peten, by tapping copal trees for sixteen weeks using two tapping methods (Tl and T2). A selection of environmental and biological variables was recorded. Part two monitored the tapped trees and a sample of untapped copal trees within the study area for weekly levels of phenological activity. Part three consisted of an ethnobotanical survey of the local knowledge of the copal tree, conducted with twenty individuals from four communities near the study area knowledgeable in local forest plants and their uses. The results from the resin yield study indicated that the variables that described tree size and health were the greatest determinants of resin production, although unpredictable tree-totree variability in resin-producing capacity was shown to significantly influence resin yield. No significant difference was observed between the two tapping methods in terms of resin yield, but Tl provided a cleaner resin that required less time and effort to collect. A conservative estimate of resin production in the study area is 2.4 kg/ha, providing a preliminary estimate of 66, 000 kg of resin for the CCFC per year with a tapping period of sixteen weeks from February to May. Overall phenological activity rose significantly from mid to late February (flowering), and from early to late April (fruiting and new foliage). The level of tapping used in the study had a significant and positive effect on phenological activity on two of the sixteen data collection dates. The ethnobotanical survey revealed the resin is the most commonly used part of the copal tree. The resin is best known locally for its use as ceremonial and healing incense, but also has many medicinal functions, including the relief of muscular pain, arthritis, rheumatism, treatment of cavities, removal of various skin ailments and in the treatment of wounds and bruises.
Surface-mode microcavity
Creators: name: Xiao, Sanshui
name: Qiu, Min
Publisher: name: arXiv
Year: 2005
Subjects: subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: Optical microcavities based on zero-group-velocity surface modes in photonic crystal slabs are studied. It is shown that high quality factors can be easily obtained for such microcavities in photonic crystal slabs. With increasing of the cavity length, the quality factor is gradually enhanced and the resonant frequency converges to that of the zero-group-velocity surface mode in the photonic crystal. The number of the resonant modes with high quality factors is mainly determined by the number of surface modes with zero-group velocity.
description: 11 pages, 4 figures
Decay of quasiparticles in quantum spin liquids
Creators: name: Zhitomirsky, M. E.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: Magnetic excitations are studied in gapped quantum spin systems, for which spontaneous two-magnon decays are allowed by symmetry. Interaction between one- and two-particle states acquires nonanalytic frequency and momentum dependence near the boundary of two-magnon continuum. This leads to a termination point of single-particle branch for one-dimensional systems and to strong suppression of quasiparticle weight in two dimensions. The momentum dependence of the decay rate is calculated in arbitrary dimensions and effect of external magnetic field is discussed.
description: 4 pages, 2 figures
Evaluating Galaxy Dynamical Masses From Kinematics and Jeans Equilibrium in Simulations
Creators: name: Kretschmer, Michael
name: Dekel, Avishai
name: Freundlich, Jonathan
name: Lapiner, Sharon
name: Ceverino, Daniel
name: Primack, Joel
Publisher: name: arXiv
Year: 2020
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We provide prescriptions to evaluate the dynamical mass ($M_{\rm dyn}$) of galaxies from kinematic measurements of stars or gas using analytic considerations and the VELA suite of cosmological zoom-in simulations at $z=1-5$. We find that Jeans or hydrostatic equilibrium is approximately valid for galaxies of stellar masses above $M_\star \!\sim\! 10^{9.5}M_\odot$ out to $5$ effective radii ($R_e$). When both measurements of the rotation velocity $v_ϕ$ and of the radial velocity dispersion $σ_r$ are available, the dynamical mass $M_{\rm dyn} \!\simeq\! G^{-1} V_c^2 r$ can be evaluated from the Jeans equation $V_c^2= v_ϕ^2 + ασ_r^2$ assuming cylindrical symmetry and a constant, isotropic $σ_r$. For spheroids, $α$ is inversely proportional to the Sérsic index $n$ and $α\simeq 2.5$ within $R_e$ for the simulated galaxies. The prediction for a self-gravitating exponential disc, $α= 3.36(r/R_e)$, is invalid in the simulations, where the dominant spheroid causes a weaker gradient from $α\!\simeq\! 1$ at $R_e$ to 4 at $5R_e$. The correction in $α$ for the stars due to the gradient in $σ_r(r)$ is roughly balanced by the effect of the aspherical potential, while the effect of anisotropy is negligible. When only the effective projected velocity dispersion $σ_l$ is available, the dynamical mass can be evaluated as $M_{\rm dyn} = K G^{-1} R_e σ_l^2$, where the virial factor $K$ is derived from $α$ given the inclination and $v_ϕ/σ_r$. We find that the standard value $K=5$ is approximately valid only when averaged over inclinations and for compact and thick discs, as it ranges from 4.5 to above 10 between edge-on and face-on projections.
description: 16 pages, 11 figures, published in MNRAS
Charged Axially Symmetric Solution, Energy and Angular Momentum in Tetrad Theory of Gravitation
Creators: name: Nashed, Gamal G. L.
Publisher: name: arXiv
Year: 2005
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: Charged axially symmetric solution of the coupled gravitational and electromagnetic fields in the tetrad theory of gravitation is derived. The metric associated with this solution is an axially symmetric metric which is characterized by three parameters ``$ $the gravitational mass $M$, the charge parameter $Q$ and the rotation parameter $a$". The parallel vector fields and the electromagnetic vector potential are axially symmetric. We calculate the total exterior energy. The energy-momentum complex given by Møller in the framework of the Weitzenb$\ddot{o}$ck geometry ``$ ${\it characterized by vanishing the curvature tensor constructed from the connection of this geometry}" has been used. This energy-momentum complex is considered as a better definition for calculation of energy and momentum than those of general relativity theory. The energy contained in a sphere is found to be consistent with pervious results which is shared by its interior and exterior. Switching off the charge parameter, one finds that no energy is shared by the exterior of the charged axially symmetric solution. The components of the momentum density are also calculated and used to evaluate the angular momentum distribution. We found no angular momentum contributes to the exterior of the charged axially symmetric solution if zero charge parameter is used.
description: LaTex file, 16 pages. accepted for publication in Modern physics letter A
On Nonlanding Dynamic Rays of Exponential Maps
Creators: name: Rempe, Lasse
Publisher: name: arXiv
Year: 2005
Subjects: subject: Dynamical Systems (math.DS)
subject: Complex Variables (math.CV)
subject: FOS: Mathematics
subject: 37F10; 30D05

description: We consider the case of an exponential map for which the singular value is accessible from the set of escaping points. We show that there are dynamic rays of which do not land. In particular, there is no analog of Douady's ``pinched disk model'' for exponential maps whose singular value belongs to the Julia set. We also prove that the boundary of a Siegel disk $U$ for which the singular value is accessible both from the set of escaping points and from $U$ contains uncountably many indecomposable continua.
description: 15 pages; 1 figure. V2: A result on Siegel disks, as well as a figure, has been added. Some minor corrections were also made
Scaling Laws of Stress and Strain in Brittle Fracture
Creators: name: Skjetne, Bjorn
name: Helle, Torbjorn
name: Hansen, Alex
Publisher: name: arXiv
Year: 2005
Subjects: subject: Soft Condensed Matter (cond-mat.soft)
subject: FOS: Physical sciences

description: A numerical realization of an elastic beam lattice is used to obtain scaling exponents relevant to the extent of damage within the controlled, catastrophic and total regimes of mode-I brittle fracture. The relative fraction of damage at the onset of catastrophic rupture approaches a fixed value in the continuum limit. This enables disorder in a real material to be quantified through its relationship with random samples generated on the computer.
description: 4 pages and 6 figures
Near-IR Spectroscopy of a Young Super-Star Cluster in NGC 6946: Chemical Abundances and Abundance Patterns
Creators: name: Larsen, S. S.
name: Origlia, L.
name: Brodie, J. P.
name: Gallagher, J. S.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: Using the NIRSPEC spectrograph at Keck II, we have obtained H and K-band echelle spectra for a young (10-15 Myr), luminous (MV=-13.2) super-star cluster in the nearby spiral galaxy NGC 6946. From spectral synthesis and equivalent width measurements we obtain for the first time accurate abundances and abundance patterns in an extragalactic super-star cluster. We find [Fe/H]=-0.45+/-0.08 dex, an average alpha-enhancement of +0.22+/-0.1 dex, and a relatively low 12C/13C~ 8+/-2 isotopic ratio. We also measure a velocity dispersion of ~9.1 km/s, in agreement with previous estimates. We conclude that integrated high-dispersion spectroscopy of massive star clusters is a promising alternative to other methods for abundance analysis in extragalactic young stellar populations.
description: 5 pages, incl. 2 figures. Accepted for publication in MNRAS Letters. The definitive version will be available at http://www.blackwell-synergy.com
Leishmania Encodes a Bacterium-like 2,4-Dienoyl-Coenzyme A Reductase That Is Required for Fatty Acid β-Oxidation and Intracellular Parasite Survival
Creators: name: Semini, Geo
name: Paape, Daniel
name: Blume, Martin
name: Sernee, M. Fleur
name: Peres-Alonso, Diego
name: Calvignac-Spencer, Sébastien
name: Döllinger, Jörg
name: Jehle, Stefan
name: Saunders, Eleanor
name: McConville, Malcolm J.
name: Aebischer, Toni
Publisher: name: Robert Koch-Institut
Year: 2020
Subjects: subject: Kinetoplastida
subject: lateral gene transfer
subject: mitochondrial metabolism
subject: virulence factors
subject: 610 Medizin und Gesundheit

description: Leishmaniaspp. are protozoan parasites that cause a spectrum of im-portant diseases in humans. These parasites develop as extracellular promastigotesin the digestive tract of their insect vectors and as obligate intracellular amastigotesthat infect macrophages and other phagocytic cells in their vertebrate hosts.Promastigote-to-amastigote differentiation is associated with marked changes in me-tabolism, including the upregulation of enzymes involved in fatty acid -oxidation,which may reflect adaptation to the intracellular niche. Here, we have investigatedthe function of one of these enzymes, a putative 2,4-dienoyl-coenzyme A (CoA) re-ductase (DECR), which is specifically required for the -oxidation of polyunsaturatedfatty acids. TheLeishmaniaDECR shows close homology to bacterial DECR proteins,suggesting that it was acquired by lateral gene transfer. It is present in othertrypanosomatids that have obligate intracellular stages (i.e.,Trypanosoma cruziandAngomonas) but is absent from dixenous parasites with an exclusively extracellularlifestyle (i.e.,Trypanosoma brucei). A DECR-green fluorescent protein (GFP) fusionprotein was localized to the mitochondrion in both promastigote and amastigotestages, and the levels of expression increased in the latter stages. ALeishmania ma-jorΔdecrnull mutant was unable to catabolize unsaturated fatty acids and accumu-lated the intermediate 2,4-decadienoyl-CoA, confirming DECR’s role in -oxidation.Strikingly, theL. majorΔdecrmutant was unable to survive in macrophages and wasavirulent in BALB/c mice. These findings suggest that -oxidation of polyunsaturatedfatty acids is essential for intracellular parasite survival and that the bacterial originof key enzymes in this pathway could be exploited in developing new therapies.
The diverse nature and formation paths of slow rotator galaxies in the EAGLE simulations
Creators: name: Lagos, Claudia del P.
name: Emsellem, Eric
name: van de Sande, Jesse
name: Harborne, Katherine E.
name: Cortese, Luca
name: Davison, Thomas
name: Foster, Caroline
name: Wright, Ruby J.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We use a sample of $z=0$ galaxies visually classified as slow rotators (SRs) in the EAGLE hydrodynamical simulations to explore the effect of galaxy mergers on their formation, characterise their intrinsic galaxy properties, and study the connection between quenching and kinematic transformation. SRs that have had major or minor mergers (mass ratios $\ge 0.3$ and $0.1-0.3$, respectively) tend to have a higher triaxiality parameter and ex-situ stellar fractions than those that had exclusively very minor mergers or formed in the absence of mergers ("no-merger" SRs). No-merger SRs are more compact, have lower black hole-to-stellar mass ratios and quenched later than other SRs, leaving imprints on their $z=0$ chemical composition. For the vast majority of SRs we find that quenching, driven by active galactic nuclei feedback, precedes kinematic transformation, except for satellite SRs, in which these processes happen in tandem. However, in $\approx 50$\% of these satellites, satellite-satellite mergers are responsible for their SR fate, while environment (i.e. tidal field and interactions with the central) can account for the transformation in the rest. By splitting SRs into kinematic sub-classes, we find that flat SRs prefer major mergers; round SRs prefer minor or very minor mergers; prolate SRs prefer gas-poor mergers. Flat and prolate SRs are more common among satellites hosted by massive halos ($>10^{13.6}\,\rm M_{\odot}$) and centrals of high masses ($M_{\star} > 10^{10.5}\, \rm M_{\odot}$). Although EAGLE galaxies display kinematic properties that broadly agree with observations, there are areas of disagreement, such as inverted stellar age and velocity dispersion profiles. We discuss these and how upcoming simulations can solve them.
description: Accepted for publications in MNRAS. 22 pages and 20 figures. Main difference with previous version is additional panel in Fig. 7 showing Sersic index vs stellar mass for different merger histories
A Massive Planet to the Young Disc Star HD 81040
Creators: name: Sozzetti, A.
name: Udry, S.
name: Zucker, S.
name: Torres, G.
name: Beuzit, J. L.
name: Latham, D. W.
name: Mayor, M.
name: Mazeh, T.
name: Naef, D.
name: Perrier, C.
name: Queloz, D.
name: Sivan, J. -P.
Publisher: name: arXiv
Year: 2005
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We report the discovery of a massive planetary companion orbiting the young disc star HD 81040. Based on five years of precise radial-velocity measurements with the HIRES and ELODIE spectrographs, we derive a spectroscopic orbit with a period $P =1001.0$ days and eccentricity $e = 0.53$. The inferred minimum mass for the companion of $m_2\sin i = 6.86$ M$_\mathrm{Jup}$ places it in the high-mass tail of the extrasolar planet mass distribution. The radial-velocity residuals exhibit a scatter significantly larger than the typical internal measurement precision of the instruments. Based on an analysis of the Ca II H and K line cores, this is interpreted as an activity-induced phenomenon. However, we find no evidence for the period and magnitude of the radial-velocity variations to be caused by stellar surface activity. The observed orbital motion of HD 81040 is thus best explained with the presence of a massive giant planet companion.
description: 9 pages, 5 figures, 4 tables. Accepted for publication in A&A
Simulating systematic bias in attributed social networks and its effect on rankings of minority nodes
Creators: name: Stamm, Felix I.
name: Neuhäuser, Leonie
name: Lemmerich, Florian
name: Schaub, Michael T.
name: Strohmaier, Markus
Publisher: name: arXiv
Year: 2020
Subjects: subject: Social and Information Networks (cs.SI)
subject: FOS: Computer and information sciences

description: Network analysis provides powerful tools to learn about a variety of social systems. However, most analyses implicitly assume that the considered relational data is error-free, reliable and accurately reflects the system to be analysed. Especially if the network consists of multiple groups, this assumption conflicts with a range of systematic biases, measurement errors and other inaccuracies that are well documented in the literature. To investigate the effects of such errors we introduce a framework for simulating systematic bias in attributed networks. Our framework enables us to model erroneous edge observations that are driven by external node attributes or errors arising from the (hidden) network structure itself. We exemplify how systematic inaccuracies distort conclusions drawn from network analyses on the network analysis task of minority representations in degree-based rankings. By analysing synthetic and real networks with varying homophily levels and group sizes, we find that introducing systematic edge errors can result both in a strongly increased or decreased ranking of the minority. The observed effect depends both on the type of edge error considered and level of homophily in the system. We thus conclude that the implications of systematic bias in edge data depend on an interplay between network topology and type of systematic error. This emphasises the need for an error model framework as developed here, which provides a first step towards studying the effects of systematic edge-uncertainty for various network analysis tasks.
Inflation with violation of the null energy condition
Creators: name: Baldi, Marco
name: Finelli, Fabio
name: Matarrese, Sabino
Publisher: name: arXiv
Year: 2005
Subjects: subject: Astrophysics (astro-ph)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: Inflation may have been driven by a component which violated the Null-Energy Condition, thereby leading to {\it super inflation}. We provide the formalism to study cosmological perturbations when such a component is described by a scalar field with arbitrary Lagrangian. Since the background curvature grows with time, gravitational waves always have a blue spectrum. Scalar perturbations may also have a blue spectrum, {\em albeit} in single field models. We apply our formalism to the case of phantom inflation with an exponential potential (whose pole-like inflationary stage is an attractor for inhomogeneous cosmological models for any value of the potential slope). We finally compare the predictions of super inflation with those of standard inflation stressing the role of gravitational waves.
description: 5 pages, 2 figures. Title modified, second figure added, results unchanged. Version accepted in PRD
TOASTED FORESTS - EVERGREEN RAIN FORESTS OF TROPICAL ASIA UNDER DROUGHT STRESS
Creators: name: Werner, Wolfgang
name: Werner, Wolfgang
Publisher: name: Unknown
Year: 2003
Subjects: Resource /Energy Economics and Policy

description: This paper has been written to make an enormous threat known to the public. We all know about the forest fires that raged in Indonesia and parts of Malaysia in 1997, and about the noxious haze covering the whole region, but only a few experts are aware of the threat of extinction of the last rain forest areas in Southeast Asia. As this paper will show, droughts have always been a part of these ecosystems, which normally receive plenty of rain. Mild droughts can be regarded as slight or medium disturbances, which can even have a stimulating effect according to the Intermediate Disturbance Hypothesis. However, severe droughts and fires have a destructive effect, which will only be overcome in successional stages. Logging and forest fragmentation reduce the ability of forests to overcome severe droughts. Forest fires rage in selectively logged forests, whereas they are extremely rare in undisturbed rain forests. Forest regeneration in fragmented forests is disturbed, so that we have to expect a total degradation of even effectively protected forest areas. Due to drought and fire, the remnant rain forest areas are being roasted like slices of toast . New research is also revealing that rain forests under drought stress consume more oxygen than they produce. The "green lung" and carbon sink are thus out of function. Furthermore, severe ENSO-(El Niño/Southern Oscillation)-droughts have been increasing in recent years. The consequences both for development of the region and for the whole atmosphere are imminent. Forest fires during ENSO droughts have caused extensive damage to forests and plantations, and noxious haze clouds in the whole region. Awareness about ENSO and droughts exists and is growing within the local population. Strict regulations, drought and fire alerts, and law enforcement can reduce at least the effects of drought. A logging ban, also including selective logging, may have to be considered. While this paper covers the whole of tropical Asia, it focuses on Sumatra, Borneo and the Malay Peninsula, which are the main evergreen rain forest areas. Other areas in the region have either seasonal vegetation, which is more drought adapted, or only small pockets of evergreen rain forest depending on local rain exposure - or the lowland forests have disappeared. The paper concentrates on Western Indonesia, Malaysia and the very south of Thailand.