cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Cosmological Measurements with Forthcoming Radio Continuum Surveys
Creators: name: Raccanelli, Alvise
name: Zhao, Gong-Bo
name: Bacon, David J.
name: Jarvis, Matt J.
name: Percival, Will J.
name: Norris, Ray P.
name: Rottgering, Huub
name: Abdalla, Filipe B.
name: Cress, Catherine M.
name: Kubwimana, Jean-Claude
name: Lindsay, Sam
name: Nichol, Robert C.
name: Santos, Mario G.
name: Schwarz, Dominik J.
Publisher: name: arXiv
Year: 2011
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: We present forecasts for constraints on cosmological models which can be obtained by forthcoming radio continuum surveys: the wide surveys with the LOw Frequency ARray (LOFAR), Australian Square Kilometre Array Pathfinder (ASKAP) and the Westerbork Observations of the Deep APERTIF Northern sky (WODAN). We use simulated catalogues appropriate to the planned surveys to predict measurements obtained with the source auto-correlation, the cross-correlation between radio sources and CMB maps (the Integrated Sachs-Wolfe effect), the cross-correlation of radio sources with foreground objects due to cosmic magnification, and a joint analysis together with the CMB power spectrum and supernovae. We show that near future radio surveys will bring complementary measurements to other experiments, probing different cosmological volumes, and having different systematics. Our results show that the unprecedented sky coverage of these surveys combined should provide the most significant measurement yet of the Integrated Sachs-Wolfe effect. In addition, we show that using the ISW effect will significantly tighten constraints on modified gravity parameters, while the best measurements of dark energy models will come from galaxy auto-correlation function analyses. Using the combination of EMU and WODAN to provide a full sky survey, it will be possible to measure the dark energy parameters with an uncertainty of \{$σ(w_0) = 0.05$, $σ(w_a) = 0.12$\} and the modified gravity parameters \{$σ(η_0) = 0.10$, $σ(μ_0) = 0.05$\}, assuming Planck CMB+SN(current data) priors. Finally, we show that radio surveys would detect a primordial non-Gaussianity of $f_{\rm NL}$ = 8 at 1-$σ$ and we briefly discuss other promising probes.
description: 19 pages, 16 figures, 2 tables; submitted to MNRAS
Influence of language on perception and concept formation in a brain-constrained deep neural network model
Creators: name: Henningsen-Schomers, Malte R.
name: Garagnani, Max
name: Pulvermüller, Friedemann
Publisher: name: Freie Universität Berlin
Year: 2022
Subjects: subject: linguistic relativity
subject: concepts
subject: deep neural networks‌
subject: neurocomputational modelling
subject: Hebbian learning
subject: cognition
subject: 500 Naturwissenschaften und Mathematik::570 Biowissenschaften; Biologie::570 Biowissenschaften; Biologie

description: A neurobiologically constrained model of semantic learning in the human brain was used to simulate the acquisition of concrete and abstract concepts, either with or without verbal labels. Concept acquisition and semantic learning were simulated using Hebbian learning mechanisms. We measured the network's category learning performance, defined as the extent to which it successfully (i) grouped partly overlapping perceptual instances into a single (abstract or concrete) conceptual representation, while (ii) still distinguishing representations for distinct concepts. Co-presence of linguistic labels with perceptual instances of a given concept generally improved the network's learning of categories, with a significantly larger beneficial effect for abstract than concrete concepts. These results offer a neurobiological explanation for causal effects of language structure on concept formation and on perceptuo-motor processing of instances of these concepts: supplying a verbal label during concept acquisition improves the cortical mechanisms by which experiences with objects and actions along with the learning of words lead to the formation of neuronal ensembles for specific concepts and meanings. Furthermore, the present results make a novel prediction, namely, that such ‘Whorfian’ effects should be modulated by the concreteness/abstractness of the semantic categories being acquired, with language labels supporting the learning of abstract concepts more than that of concrete ones.
Hadron-quark phase transition in a hadronic and Polyakov--Nambu--Jona-Lasinio models perspective
Creators: name: Lourenço, O.
name: Dutra, M.
name: Delfino, A.
name: Malheiro, M.
Publisher: name: arXiv
Year: 2012
Subjects: subject: Nuclear Theory (nucl-th)
subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: In this work we study the hadron-quark phase transition matching relativistic hadrodynamical mean-field models (in the hadronic phase) with the more updated versions of the Polyakov-Nambu-Jona-Lasinio models (on the quark side). Systematic comparisons are performed showing that the predicted hadronic phases of the matching named as RMF-PNJL, are larger than the confined phase obtained exclusively by the Polyakov quark models. This important result is due to the effect of the nuclear force that causes more resistance of hadronic matter to isothermal compressions. For sake of comparison, we also obtain the matchings of the hadronic models with the MIT bag model, named as RMF-MIT, showing that it presents always larger hadron regions, while shows smaller mixed phases than that obtained from the RMF-PNJL ones. Thus, studies of the confinement transition in nuclear matter, done only with quark models, still need nuclear degrees of freedom to be more reliable in the whole $T\timesμ$ phase diagram.
description: 31 pages, 8 figures (revtex)
Transcriptome changes induced by Arbuscular mycorrhizal symbiosis in leaves of durum wheat (Triticum durum Desf.) promote higher salt tolerance
Creators: name: Puccio, Guglielmo
name: Ingraffia, Rosolino
name: Mercati, Francesco
name: Amato, Gaetano
name: Giambalvo, Dario
name: Martinelli, Federico
name: Sunseri, Francesco
name: Frenda, Alfonso S.
Publisher: name: Freie Universität Berlin
Year: 2023
Subjects: subject: Arbuscular mycorrhiza
subject: Bioinformatics
subject: FOS: Computer and information sciences
subject: Plant genetics
subject: Plant stress responses
subject: Plant symbiosis
subject: 500 Naturwissenschaften und Mathematik::570 Biowissenschaften; Biologie::570 Biowissenschaften; Biologie

description: The salinity of soil is a relevant environmental problem around the world, with climate change raising its relevance, particularly in arid and semiarid areas. Arbuscular Mycorrhizal Fungi (AMF) positively affect plant growth and health by mitigating biotic and abiotic stresses, including salt stress. The mechanisms through which these benefits manifest are, however, still unclear. This work aimed to identify key genes involved in the response to salt stress induced by AMF using RNA-Seq analysis on durum wheat (Triticum turgidum L. subsp. durum Desf. Husn.). Five hundred sixty-three differentially expressed genes (DEGs), many of which involved in pathways related to plant stress responses, were identified. The expression of genes involved in trehalose metabolism, RNA processing, vesicle trafficking, cell wall organization, and signal transduction was significantly enhanced by the AMF symbiosis. A downregulation of genes involved in both enzymatic and non-enzymatic oxidative stress responses as well as amino acids, lipids, and carbohydrates metabolisms was also detected, suggesting a lower oxidative stress condition in the AMF inoculated plants. Interestingly, many transcription factor families, including WRKY, NAC, and MYB, already known for their key role in plant abiotic stress response, were found differentially expressed between treatments. This study provides valuable insights on AMF-induced gene expression modulation and the beneficial effects of plant-AMF interaction in durum wheat under salt stress.
[Segl tilhørende Jonas Lie]
Creators: name: Lie, Jonas
Publisher: name: Unknown
Year: 0

description: Blasonering av skjoldet: Ikke skjold. I seglet en kvinne holdende bokstaven L.
description: Beskrivelse av segl og andre opplysninger er hentet fra boka "Segl i Universitetsbiblioteket i Trondheim" av Harald Nissen og Monica Aase utgitt 1990.
Antlia Dwarf Galaxy: Distance, quantitative morphology and recent formation history via statistical field correction
Creators: name: Pimbblet, Kevin A.
name: Couch, Warrick J.
Publisher: name: arXiv
Year: 2011
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: We apply a statistical field correction technique originally designed to determine membership of high redshift galaxy clusters to Hubble Space Telescope imaging of the Antlia Dwarf Galaxy; a galaxy at the very edge of the Local Group. Using the tip of the red giant branch standard candle method coupled with a simple Sobel edge detection filter we find a new distance to Antlia of 1.31 +/- 0.03 Mpc. For the first time for a Local Group Member, we compute the concentration, asymmetry and clumpiness (CAS) quantitative morphology parameters for Antlia from the distribution of resolved stars in the HST/ACS field, corrected with a new method for contaminants and complement these parameters with the Gini coefficient (G) and the second order moment of the brightest 20 per cent of the flux (M_20). We show that it is a classic dwarf elliptical (C = 2.0, A = 0.063, S = 0.077, G = 0.39 and M_20 = -1.17 in the F814W band), but has an appreciable blue stellar population at its core, confirming on-going star-formation. The values of asymmetry and clumpiness, as well as Gini and M_20 are consistent with an undisturbed galaxy. Although our analysis suggests that Antlia may not be tidally influenced by NGC 3109 it does not necessarily preclude such interaction.
description: Accepted for publication in MNRAS
[Segl tilhørende Hans Jürgen Bauck]
Creators: name: Bauck, Hans Jürgen
Publisher: name: Unknown
Year: 0

description: Blasonering av skjoldet: I skjoldet ni roser med stilker og blad bundet sammen med et band.
description: Blasonering av hjelmtegnet: Mglr. hjelm. Over skjoldet en krone med tre blad og to perler. Under kronen bokstavene HIB.
description: Beskrivelse av segl og andre opplysninger er hentet fra boka "Segl i Universitetsbiblioteket i Trondheim" av Harald Nissen og Monica Aase utgitt 1990.
[Segl tilhørende Heinrich Bauck]
Creators: name: Bauck, Heinrich
Publisher: name: Unknown
Year: 0

description: Monogramsegl: Bokstavene HB.
description: Beskrivelse av segl og andre opplysninger er hentet fra boka "Segl i Universitetsbiblioteket i Trondheim" av Harald Nissen og Monica Aase utgitt 1990.
Direct Observation of Ultrafast Lattice Distortions during Exciton–Polaron Formation in Lead Halide Perovskite Nanocrystals
Creators: name: Seiler, Hélène
name: Zahn, Daniela
name: Taylor, Victoria C. A.
name: Bodnarchuk, Maryna I.
name: Windsor, Yoav William
name: Kovalenko, Maksym V.
name: Ernstorfer, Ralph
Publisher: name: Freie Universität Berlin
Year: 2023
Subjects: subject: Diffraction
subject: Lattices
subject: Perovskites
subject: 500 Naturwissenschaften und Mathematik::540 Chemie::540 Chemie und zugeordnete Wissenschaften

description: The microscopic origin of slow hot-carrier cooling in lead halide perovskites remains debated and has direct implications for applications. Slow hot-carrier cooling of several picoseconds has been attributed to either polaron formation or a hot-phonon bottleneck effect at high excited carrier densities (>1018 cm–3). These effects cannot be unambiguously disentangled with optical experiments alone. However, they can be distinguished by direct observations of ultrafast lattice dynamics, as these effects are expected to create qualitatively distinct fingerprints. To this end, we employ femtosecond electron diffraction and directly measure the sub-picosecond lattice dynamics of weakly confined CsPbBr3 nanocrystals following above-gap photoexcitation. While we do not observe signatures of a hot-phonon bottleneck lasting several picoseconds, the data reveal a light-induced structural distortion appearing on a time scale varying between 380 and 1200 fs depending on the excitation fluence. We attribute these dynamics to the effect of exciton–polarons on the lattice and the slower dynamics at high fluences to slower sub-picosecond hot-carrier cooling, which slows down the establishment of the exciton–polaron population. Further analysis and simulations show that the distortion is consistent with motions of the [PbBr3]− octahedral ionic cage, and closest agreement with the data is obtained for Pb–Br bond lengthening. Our work demonstrates how direct studies of lattice dynamics on the sub-picosecond time scale can discriminate between competing scenarios proposed in the literature to explain the origin of slow hot-carrier cooling in lead halide perovskites.
Spin orientation by electric current in (110) quantum wells
Creators: name: Golub, L. E.
name: Ivchenko, E. L.
Publisher: name: arXiv
Year: 2011
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: We develop a theory of spin orientation by electric current in (110)-grown semiconductor quantum wells. The controversy in the factor of two from two existed approaches is resolved by pointing out the importance of energy relaxation in this problem. The limiting cases of fast and slow energy relaxation relative to spin relaxation are considered for asymmetric (110) quantum wells. For symmetricly-doped structures the effect of spin orientation is shown to exist due to spatial fluctuations of the Rashba spin-orbit splitting. We demonstrate that the spin orientation depends strongly on the correlation length of these fluctuations as well as on the ratio of the energy and spin relaxation rates. The time-resolved kinetics of spin polarization by electric current is also governed by the correlation length being not purely exponential at slow energy relaxation. Electrical spin orientation in two-dimensional topological insulators is calculated and compared with the spin polarization induced by the magnetic field.
description: 8 pages, 2 figures
[Segl tilhørende Niels Perbøl]
Creators: name: Perbøl, Niels
Publisher: name: Unknown
Year: 0

description: Monogramsegl: Bokstavene N P.
description: Beskrivelse av segl og andre opplysninger er hentet fra boka "Segl i Universitetsbiblioteket i Trondheim" av Harald Nissen og Monica Aase utgitt 1990.
The coherent interaction between matter and radiation - A tutorial on the Jaynes-Cummings model
Creators: name: Bina, Matteo
Publisher: name: arXiv
Year: 2011
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: The Jaynes-Cummings (JC) model is a milestone in the theory of coherent interaction between a two-level system and a single bosonic field mode. This tutorial aims to give a complete description of the model, analyzing the Hamiltonian of the system, its eigenvalues and eigestates, in order to characterize the dynamics of system and subsystems. The Rabi oscillations, together with the collapse and revival effects, are distinguishing features of the JC model and are important for applications in Quantum Information theory. The framework of cavity quantum electrodynamics (cQED) is chosen and two fundamental experiments on the coherent interaction between Rydberg atoms and a single cavity field mode are described.
description: 22 pages, 7 figures. Tutorial. Submitted to a special issue of EPJ - ST devoted to the memory of Federico Casagrande
[Segl tilhørende Christen Alfsen]
Creators: name: Alfsen, Christen
Publisher: name: Unknown
Year: 0

description: Blasonering av skjoldet: I skjoldet en rose.
description: Blasonering av hjelmtegnet: På hjelmen en fugl med en kvist i nebbet. Deromkring bokstavene M C D.
description: Merknad: Farmorens signet, Margrethe Petersdatter Denim?.
description: Beskrivelse av segl og andre opplysninger er hentet fra boka "Segl i Universitetsbiblioteket i Trondheim" av Harald Nissen og Monica Aase utgitt 1990.
Re-evaluation of Cerebropollenites thiergartii Eberh.Schulz 1967 and related taxa: priority of Sciadopityspollenites and nomenclatural novelties
Creators: name: Gravendyck, Julia
name: Coiffard, Clément
name: Bachelier, Julien B.
name: Kürschner, Wolfram
Publisher: name: Freie Universität Berlin
Year: 2023
Subjects: subject: taxonomy
subject: revision
subject: marker fossil
subject: Triassic–Jurassic
subject: Tsugaepollenites
subject: macroverrucosus
subject: mesozoicus
subject: 500 Naturwissenschaften und Mathematik::580 Pflanzen (Botanik)::580 Pflanzen (Botanik)

description: The important marker species for the base of the Jurassic, Cerebropollenites thiergartii, occurs contemporaneously with at least nine related taxa. However, their distinction is difficult and has been confused in the past. In addition, a long history of numerous recombinations with different genus names (e.g. Tsugaepollenites and Sciadopityspollenites), and inconsistent classifications or synonymisations, further complicate the taxonomic framework of Cerebropollenites thiergartii. A comprehensive study of these ten taxa, summarising their crucial distinctive characteristics and potential synonymy, is currently missing. This limits the stratigraphic value of Cerebropollenites thiergartii and associated taxa relevant to the Triassic–Jurassic transition. Here, we revisit relevant holotype material, related taxa and investigated new material for potential interspecific and intraspecific morphological variation. Based on an empirical analysis of name use and an extensive literature review, we identified previous sources of confusion, re-evaluated the distinctive characteristics and stratigraphic value of these taxa, and their relevance for the Triassic–Jurassic transition. Finally, we argue that the recombination as Sciadopityspollenites thiergartii is taxonomically and nomenclaturally imperative, not only due to priority, but also because it unifies previous disjunct use of Cerebropollenites for Mesozoic and Sciadopityspollenites for Cenozoic taxa, or Mesozoic species in many Russian studies. Thus, we propose a series of nomenclatural novelties: Sciadopityspollenites emend., Sciadopityspollenites thiergartii comb. nov. et emend., S. thiergartii ssp. nov. thiergartii, S. thiergartii ssp. multiverrucosus stat. nov., S. megaorbicularius sp. nov., S. carlylensis comb. nov. et emend., S. serratus emend., S. macroverrucosus emend., S. mesozoicus emend., Cryptopalynites gen. nov., Cryptopalynites pseudomassulae comb. nov. et emend.
[Segl tilhørende Niels Rosing Bull]
Creators: name: Bull, Niels Rosing
Publisher: name: Unknown
Year: 0

description: Blasonering av skjoldet: I skjoldet i blått en stubbe fra jord.
description: Blasonering av hjelmtegnet: Mglr. hjelmtegn.
description: Beskrivelse av segl og andre opplysninger er hentet fra boka "Segl i Universitetsbiblioteket i Trondheim" av Harald Nissen og Monica Aase utgitt 1990.
Unconventional secretion of unglycosylated ORF8 is critical for the cytokine storm during SARS-CoV-2 infection
Creators: name: Lin, Xiaoyuan
name: Fu, Beibei
name: Xiong, Yan
name: Xing, Na
name: Xue, Weiwei
name: Guo, Dong
name: Zaky, Mohamed
name: Pavani, Krishna
name: Kunec, Dusan
name: Trimpert, Jakob
Publisher: name: Freie Universität Berlin
Year: 2023
Subjects: subject: SARS CoV 2
subject: Cytokines
subject: Glycosylation
subject: 600 Technik, Medizin, angewandte Wissenschaften::610 Medizin und Gesundheit::616 Krankheiten

description: Coronavirus disease 2019 is a respiratory infectious disease caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Evidence on the pathogenesis of SARS-CoV-2 is accumulating rapidly. In addition to structural proteins such as Spike and Envelope, the functional roles of non-structural and accessory proteins in regulating viral life cycle and host immune responses remain to be understood. Here, we show that open reading frame 8 (ORF8) acts as messenger for inter-cellular communication between alveolar epithelial cells and macrophages during SARS-CoV-2 infection. Mechanistically, ORF8 is a secretory protein that can be secreted by infected epithelial cells via both conventional and unconventional secretory pathways. Conventionally secreted ORF8 is glycosylated and loses the ability to recognize interleukin 17 receptor A of macrophages, possibly due to the steric hindrance imposed by N-glycosylation at Asn78. However, unconventionally secreted ORF8 does not undergo glycosylation without experiencing the ER-Golgi trafficking, thereby activating the downstream NF-κB signaling pathway and facilitating a burst of cytokine release. Furthermore, we show that ORF8 deletion in SARS-CoV-2 attenuates inflammation and yields less lung lesions in hamsters. Our data collectively highlights a role of ORF8 protein in the development of cytokine storms during SARS-CoV-2 infection.
Cholesterol promotes clustering of PI(4,5)P2 driving unconventional secretion of FGF2
Creators: name: Lolicato, Fabio
name: Saleppico, Roberto
name: Griffo, Alessandra
name: Meyer, Annalena
name: Scollo, Federica
name: Pokrandt, Bianca
name: Müller, Hans-Michael
name: Ewers, Helge
name: Hähl, Hendrik
name: Fleury, Jean-Baptiste
Publisher: name: Freie Universität Berlin
Year: 2022
Subjects: subject: Biochemistry
subject: Biophysics
subject: Membrane and lipid biology
subject: Trafficking
subject: 500 Naturwissenschaften und Mathematik::570 Biowissenschaften; Biologie::570 Biowissenschaften; Biologie

description: FGF2 is a cell survival factor involved in tumor-induced angiogenesis that is secreted through an unconventional secretory pathway based upon direct protein translocation across the plasma membrane. Here, we demonstrate that both PI(4,5)P2-dependent FGF2 recruitment at the inner plasma membrane leaflet and FGF2 membrane translocation into the extracellular space are positively modulated by cholesterol in living cells. We further revealed cholesterol to enhance FGF2 binding to PI(4,5)P2-containing lipid bilayers. Based on extensive atomistic molecular dynamics (MD) simulations and membrane tension experiments, we proposed cholesterol to modulate FGF2 binding to PI(4,5)P2 by (i) increasing head group visibility of PI(4,5)P2 on the membrane surface, (ii) increasing avidity by cholesterol-induced clustering of PI(4,5)P2 molecules triggering FGF2 oligomerization, and (iii) increasing membrane tension facilitating the formation of lipidic membrane pores. Our findings have general implications for phosphoinositide-dependent protein recruitment to membranes and explain the highly selective targeting of FGF2 toward the plasma membrane, the subcellular site of FGF2 membrane translocation during unconventional secretion of FGF2.
Oscillatory critical amplitudes in hierarchical models and the tail of the Harris random variable
Creators: name: Costin, Ovidiu
name: Giacomin, Giambattista
Publisher: name: arXiv
Year: 2012
Subjects: subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences
subject: 82B27, 60J80, 37F10

description: Oscillatory critical amplitudes have been repeatedly observed in hierarchical models and, in the cases that have been taken into consideration, these oscillations are so small to be hardly detectable. Hierarchical models are tightly related to iteration of maps and, in fact, very similar phenomena have been repeatedly reported in many fields of mathematics, like combinatorial evaluations and discrete branching processes. It is precisely in the context of branching processes with bounded off-spring that T. Harris, in 1948, first set forth the possibility that the logarithm of the moment generating function of the rescaled population size, in the super-critical regime, does not grow near infinity as a power, but it has an oscillatory prefactor. These oscillations have been observed numerically only much later and, while the origin is clearly tied to the discrete character of the iteration, the amplitude size is not so well understood. The purpose of this note is to reconsider the issue for hierarchical models and in what is arguably the most elementary setting -- the pinning model -- that actually just boils down to iteration of polynomial maps (and, notably, quadratic maps). In this note we show that the oscillatory critical amplitude for pinning models and the oscillating pre factor connected to the Harris random variable coincide. Moreover we make explicit the link between these oscillatory functions and the geometry of the Julia set of the map, making thus rigorous and quantitative some ideas set forth by B. Derrida, C. Itzykson and J. M. Luck (CMP 1984).
description: 14 pages, 3 figures
Superconductivity Induced by Bond Breaking in the Triangular Lattice of IrTe2
Creators: name: Pyon, Sunseng
name: Kudo, Kazutaka
name: Nohara, Minoru
Publisher: name: arXiv
Year: 2012
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: FOS: Physical sciences

description: IrTe2, a layered compound with a triangular iridium lattice, exhibits a structural phase transition at approximately 250 K. This transition is characterized by the formation of Ir-Ir bonds along the b-axis. We found that the breaking of Ir-Ir bonds that occurs in Ir1-xPtxTe2 results in the appearance of a structural critical point in the T = 0 limit at xc = 0.035. Although both IrTe2 and PtTe2 are paramagnetic metals, superconductivity at Tc = 3.1 K is induced by the bond breaking in a narrow range of x > xc in Ir1-xPtxTe2. This result indicates that structural fluctuations can be involved in the emergence of superconductivity.
description: 10 pages, 4 figures
High-resolution debris-cover mapping using UAV-derived thermal imagery: limits and opportunities
Creators: name: Gök, Deniz Tobias
name: Scherler, Dirk
name: Anderson, Leif Stefan
Publisher: name: Freie Universität Berlin
Year: 2023
Subjects: subject: debris-cover mapping
subject: thermal imagery
subject: limits
subject: 500 Naturwissenschaften und Mathematik::550 Geowissenschaften, Geologie::550 Geowissenschaften

description: Debris-covered glaciers are widespread in high mountain ranges on earth. However, the dynamic evolution of debris-covered glacier surfaces is not well understood, in part due to difficulties in mapping debris-cover thickness in high spatiotemporal resolution. In this study, we present land surface temperatures (LSTs) of supraglacial debris cover and their diurnal variability measured from an unpiloted aerial vehicle (UAV) at a high (15 cm) spatial resolution. We test two common approaches to derive debris-thickness maps by (1) solving a surface energy balance model (SEBM) in conjunction with meteorological reanalysis data and (2) least squares regression of a rational curve using debris-thickness field measurements. In addition, we take advantage of the measured diurnal temperature cycle and estimate the rate of change of heat storage within the debris cover. Both approaches resulted in debris-thickness estimates with an RMSE of 6 to 8 cm between observed and modeled debris thicknesses, depending on the time of the day. Although the rational curve approach requires in situ field measurements, the approach is less sensitive to uncertainties in LST measurements compared to the SEBM approach. However, the requirement of debris-thickness measurements can be an inhibiting factor that supports the SEB approach. Because LST varies throughout the day, the success of a rational function to express the relationship between LST and debris thickness also varies predictably with the time of day. During the period when the debris cover is warming, LST is heavily influenced by the aspect of the terrain. As a result, clear-sky morning flights that do not consider the aspect effects can be problematic. Our sensitivity analysis of various parameters in the SEBM highlights the relevance of the effective thermal conductivity when LST is high. The residual and variable bias of UAV-derived LSTs during a flight requires calibration, which we achieve with bare-ice surfaces. The model performance would benefit from more accurate LST measurements, which are challenging to achieve with uncooled sensors in high mountain landscapes.
Are black holes a serious threat to scalar field dark matter models?
Creators: name: Barranco, Juan
name: Bernal, Argelia
name: Degollado, Juan Carlos
name: Diez-Tejedor, Alberto
name: Megevand, Miguel
name: Alcubierre, Miguel
name: Núñez, Darío
name: Sarbach, Olivier
Publisher: name: arXiv
Year: 2011
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: Classical scalar fields have been proposed as possible candidates for the dark matter component of the universe. Given the fact that super-massive black holes seem to exist at the center of most galaxies, in order to be a viable candidate for the dark matter halo a scalar field configuration should be stable in the presence of a central black hole, or at least be able to survive for cosmological time-scales. In the present work we consider a scalar field as a test field on a Schwarzschild background, and study under which conditions one can obtain long-lived configurations. We present a detailed study of the Klein-Gordon equation in the Schwarzschild spacetime, both from an analytical and numerical point of view, and show that indeed there exist quasi-stationary solutions that can remain surrounding a black hole for large time-scales.
description: 34 pages, 13 figures
Mapping atomic trapping in an optical superlattice onto the libration of a planar rotor in electric fields
Creators: name: Mirahmadi, Marjan
name: Friedrich, Bretislav
name: Schmidt, Burkhard
name: Pérez-Ríos, Jesús
Publisher: name: Freie Universität Berlin
Year: 2023
Subjects: subject: optical lattice
subject: ultracold atoms
subject: quantum rotor
subject: planar pendulum
subject: 500 Naturwissenschaften und Mathematik::530 Physik::530 Physik

description: We show that two seemingly unrelated problems—the trapping of an atom in an optical superlattice (OSL) and the libration of a planar rigid rotor in combined electric and optical fields (PR) – have isomorphic Hamiltonians. Formed by the interference of optical lattices whose spatial periods differ by a factor of two, OSL gives rise to a periodic potential that acts on atomic translation via the AC Stark effect. The PR system, also known as the generalized planar pendulum, is realized by subjecting a planar rigid rotor to combined orienting and aligning interactions due to the coupling of the rotor's permanent and induced electric dipole moments to the combined fields. The PR system belongs to the class of conditionally quasi-exactly solvable problems and exhibits intriguing spectral properties that have been established in our previous work Becker et al (2017 Eur. Phys. J. D 71 149). Herein, we make use of both the PR $\mapsto$ OSL mapping and the quasi-exact solvability of the PR system to treat ultracold atoms in an OSL as a semifinite-gap system. The band structure of this system follows from the eigenenergies and their genuine and avoided crossings obtained previously for the PR system as solutions of the Whittaker-Hill equation. These solutions characterize both the squeezing and the tunneling of atoms trapped in an OSL and pave the way to unraveling their dynamics in analytic form. Furthermore, the PR $\mapsto$ OSL mapping makes it possible to establish correspondence between concepts developed for the two eigenproblems individually, such as localization on the one hand and orientation/alignment on the other.
Chemical constraints on the formation of the Galactic thick disk
Creators: name: Bensby, T.
name: Feltzing, S.
Publisher: name: arXiv
Year: 2011
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We highlight some results from our detailed abundance analysis study of 703 kinematically selected F and G dwarf stars in the solar neighbourhood. The analysis is based on spectra of high-resolution (R=45000 to 110000) and high signal-to-noise (S/N=150 to 300). The main findings include: (1) at a given metallicity, the thick disk abundance trends are more $α$-enhanced than those of the thin disk; (2) the metal-rich limit of the thick disk reaches at least solar metallicities; (3) the metal-poor limit of the thin disk is around [Fe/H]=-0.8; (4) the thick disk shows an age-metallicity gradient; (5) the thin disk does {\it not} show an age-metallicity gradient; (6) the most metal-rich thick disk stars at [Fe/H]=0 are significantly older than the most metal-poor thin disk stars at [Fe/H]=-0.7; (7) based on our elemental abundances we find that kinematical criteria produce thin and thick disk stellar samples that are biased in the sense that stars from the low-velocity tail of the thick disk are classified as thin disk stars, and stars from the high-velocity tail of the thin disk are classified as thick disk stars; (8) age criteria appears to produce thin and thick disk stellar samples with less contamination.
description: Invited talk at the "Assembling the puzzle of the Milky Way" conference, April 17-22, 2011, in Le Grand-Bornand, France. Will be published in EPJ Web of Conferences (Edited by C\'eline Reyl\'e, Annie Robin and Mathias Schultheis)
The Optical Gravitational Lensing Experiment. The OGLE-III Catalog of Variable Stars. XIII. Long-Period Variables in the Small Magellanic Cloud
Creators: name: Soszynski, I.
name: Udalski, A.
name: Szymanski, M. K.
name: Kubiak, M.
name: Pietrzynski, G.
name: Wyrzykowski, L.
name: Ulaczyk, K.
name: Poleski, R.
name: Kozlowski, S.
name: Pietrukowicz, P.
Publisher: name: arXiv
Year: 2011
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: The thirteenth part of the OGLE-III Catalog of Variable Stars (OIII-CVS) contains 19384 long-period variables (LPVs) detected in the Small Magellanic Cloud. The sample is composed of 352 Mira stars, 2222 semiregular variables (SRVs) and 16810 OGLE Small Amplitude Red Giants (OSARGs). Sources are divided into oxygen-rich and carbon-rich stars. The catalog includes time-series VI photometry obtained between 1997 and 2009. Methods used to select and classify variable stars are described. We show some statistical properties of the sample, and compare it with LPVs in the Large Magellanic Cloud. Additionally, we present objects of particular interest, e.g. a SRV with outbursts, and a Mira star with the longest known pulsation period P=1860 days.
description: 14 pages, color figures, submitted to Acta Astronomica
Ferromagnetism and skyrmions in the Hofstadter–Fermi–Hubbard model
Creators: name: Palm, F. A.
name: Kurttutan, Mert
name: Bohrdt, A.
name: Schollwöck, U.
name: Grusdt, F.
Publisher: name: Freie Universität Berlin
Year: 2023
Subjects: subject: ultracold atoms
subject: skyrmions
subject: quantum Hall effect
subject: quantum Hall ferromagnet
subject: optical lattices
subject: 500 Naturwissenschaften und Mathematik::530 Physik::530 Physik

description: Strongly interacting fermionic systems host a variety of interesting quantum many-body states with exotic excitations. For instance, the interplay of strong interactions and the Pauli exclusion principle can lead to Stoner ferromagnetism, but the fate of this state remains unclear when kinetic terms are added. While in many lattice models the fermions' dispersion results in delocalization and destabilization of the ferromagnet, flat bands can restore strong interaction effects and ferromagnetic correlations. To reveal this interplay, here we propose to study the Hofstadter–Fermi–Hubbard model using ultracold atoms. We demonstrate, by performing large-scale density-matrix renormalization group simulations, that this model exhibits a lattice analog of the quantum Hall (QH) ferromagnet at magnetic filling factor ν = 1. We reveal the nature of the low energy spin-singlet states around ν ≈ 1 and find that they host quasi-particles and quasi-holes exhibiting spin-spin correlations reminiscent of skyrmions. Finally, we predict the breakdown of flat-band ferromagnetism at large fields. Our work paves the way towards experimental studies of lattice QH ferromagnetism, including prospects to study many-body states of interacting skyrmions and explore the relation to high-$T_\mathrm{c}$ superconductivity.
Anticontrol Techniques for Systems of Lorenz Type
Creators: name: Constantinescu, Dana
Publisher: name: arXiv
Year: 2012
Subjects: subject: Dynamical Systems (math.DS)
subject: Chaotic Dynamics (nlin.CD)
subject: FOS: Mathematics
subject: FOS: Physical sciences
subject: 37C29

description: The paper investigates some basic dynamical properties of a general system obtained from the Lorenz system using a non-linear feedback controller. We focus on the bifurcation of the equilibrium points and on the existence and the description of homoclinic and heteroclinic orbits. We present necessary conditions for the anticontrol of chaos in the considered system.
[Segl tilhørende Christen Elster]
Creators: name: Elster, Christen
Publisher: name: Unknown
Year: 0

description: Blasonering av skjoldet: I skjoldet en hjort stående på jord.
description: Blasonering av hjelmtegnet: Mglr. hjelm. Over skjoldet en sløyfe.
description: Beskrivelse av segl og andre opplysninger er hentet fra boka "Segl i Universitetsbiblioteket i Trondheim" av Harald Nissen og Monica Aase utgitt 1990.
[Segl tilhørende Henrich Christopher Sommerschild]
Creators: name: Sommerschild, Henrich Christopher
Publisher: name: Unknown
Year: 0

description: Blasonering av skjoldet: I skjoldet i purpur to halvmåner i skrårekke, den nederste sinistervendt.
description: Blasonering av hjelmtegnet: På hjelmen en harniskkledt arm holdende et sverd.
description: Beskrivelse av segl og andre opplysninger er hentet fra boka "Segl i Universitetsbiblioteket i Trondheim" av Harald Nissen og Monica Aase utgitt 1990.
On the redshift of the bright BL Lac object PKS 0048-097
Creators: name: Landoni, Marco
name: Falomo, Renato
name: Treves, Aldo
name: Sbarufatti, Boris
name: Decarli, Roberto
name: Tavecchio, Fabrizio
name: Kotilainen, Jari
Publisher: name: arXiv
Year: 2012
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: Aims: The determination of elusive redshifts of bright BL Lac objects Methods: We use the capabilities of newly available spectrograph X-Shooter at European Southern Observatory (ESO) Very Large Telescope, that combines high resolution and a large wavelength range, to obtain UVB to near-IR spectra of BL Lacs. Results: Our observations of PKS 0048-097 detect three emission lines that permit to derive a redshift z = 0.635. Moreover, a Mg II absorption system at z = 0.154 that is associated with a foreground spiral galaxy at 50 Kpc projected distance is found. Conclusions: The obtained redshift allows us to comment about the optical beaming factor and the absorption of the high energy spectrum by the Extragalactic Background Light.
description: 5 pages, 6 figures; Accepted for publication by A&A; AA/2012/19114
Programmable Photocatalytic Activity of Multicomponent Covalent Organic Frameworks Used as Metallaphotocatalysts
Creators: name: Traxler, Michael
name: Reischauer, Susanne
name: Vogl, Sarah
name: Roeser, Jérôme
name: Rabeah, Jabor
name: Penschke, Christopher
name: Saalfrank, Peter
name: Pieber, Bartholomäus
name: Thomas, Arne
Publisher: name: Freie Universität Berlin
Year: 2023
Subjects: subject: catalysis
subject: covalent organic frameworks
subject: cross-coupling
subject: photoredox
subject: tuneable activity
subject: 500 Naturwissenschaften und Mathematik::540 Chemie::540 Chemie und zugeordnete Wissenschaften

description: The multicomponent approach allows to incorporate several functionalities into a single covalent organic framework (COF) and consequently allows the construction of bifunctional materials for cooperative catalysis. The well-defined structure of such multicomponent COFs is furthermore ideally suited for structure-activity relationship studies. We report a series of multicomponent COFs that contain acridine- and 2,2’-bipyridine linkers connected through 1,3,5-benzenetrialdehyde derivatives. The acridine motif is responsible for broad light absorption, while the bipyridine unit enables complexation of nickel catalysts. These features enable the usage of the framework materials as catalysts for light-mediated carbon−heteroatom cross-couplings. Variation of the node units shows that the catalytic activity correlates to the keto-enamine tautomer isomerism. This allows switching between high charge-carrier mobility and persistent, localized charge-separated species depending on the nodes, a tool to tailor the materials for specific reactions. Moreover, nickel-loaded COFs are recyclable and catalyze cross-couplings even using red light irradiation.
Human Arm simulation for interactive constrained environment design
Creators: name: Ma, Liang
name: Ma, Ruina
name: Chablat, Damien
name: Bennis, Fouad
Publisher: name: arXiv
Year: 2012
Subjects: subject: Robotics (cs.RO)
subject: FOS: Computer and information sciences

description: During the conceptual and prototype design stage of an industrial product, it is crucial to take assembly/disassembly and maintenance operations in advance. A well-designed system should enable relatively easy access of operating manipulators in the constrained environment and reduce musculoskeletal disorder risks for those manual handling operations. Trajectory planning comes up as an important issue for those assembly and maintenance operations under a constrained environment, since it determines the accessibility and the other ergonomics issues, such as muscle effort and its related fatigue. In this paper, a customer-oriented interactive approach is proposed to partially solve ergonomic related issues encountered during the design stage under a constrained system for the operator's convenience. Based on a single objective optimization method, trajectory planning for different operators could be generated automatically. Meanwhile, a motion capture based method assists the operator to guide the trajectory planning interactively when either a local minimum is encountered within the single objective optimization or the operator prefers guiding the virtual human manually. Besides that, a physical engine is integrated into this approach to provide physically realistic simulation in real time manner, so that collision free path and related dynamic information could be computed to determine further muscle fatigue and accessibility of a product design
description: International Journal on Interactive Design and Manufacturing (IJIDeM) (2012) 1-12. arXiv admin note: substantial text overlap with arXiv:1012.4327
Destabilization of free convection by weak rotation
Creators: name: Gelfgat, Alexander
Publisher: name: arXiv
Year: 2011
Subjects: subject: Fluid Dynamics (physics.flu-dyn)
subject: FOS: Physical sciences

description: This study offers an explanation of a recently observed effect of destabilization of free convective flows by weak rotation. After studying several models where flows are driven by a simultaneous action of convection and rotation, it is concluded that the destabilization is observed in the cases where centrifugal force acts against main convective circulation. At relatively low Prandtl numbers this counter action can split the main vortex into two counter rotating vortices, where the interaction leads to instability. At larger Prandtl numbers, the counter action of the centrifugal force steepens an unstable thermal stratification, which triggers Rayleigh-Bénard instability mechanism. Both cases can be enhanced by advection of azimuthal velocity disturbances towards the axis, where they grow and excite perturbations of the radial velocity. The effect was studied considering a combined convective/rotating flow in a cylinder with a rotating lid and a parabolic temperature profile at the sidewall. Next, explanations of the destabilization effect for rotating magnetic field driven flow and melt flow in a Czochralski crystal growth model were derived.
[Segl tilhørende Andr. Christie]
Creators: name: Christie, Andr.
Publisher: name: Unknown
Year: 0

description: Blasonering av skjoldet: I skjoldet et andreaskors fulgt av fire seksoddete stjerner.
description: Blasonering av hjelmtegnet: Mglr. hjelm.
description: Blasonering av skjoldholdere: En kvinne holdende i høyre hånd skjoldet, i venstre hånd et overflødighetshorn. Sinister et blomsterkurv.
description: Beskrivelse av segl og andre opplysninger er hentet fra boka "Segl i Universitetsbiblioteket i Trondheim" av Harald Nissen og Monica Aase utgitt 1990.
Event Centric Modeling Approach in Colocation Pattern Snalysis from Spatial Data
Creators: name: Venkatesan, M.
name: Thangavelu, Arunkumar
name: Prabhavathy, P.
Publisher: name: arXiv
Year: 2011
Subjects: subject: Databases (cs.DB)
subject: FOS: Computer and information sciences

description: Spatial co-location patterns are the subsets of Boolean spatial features whose instances are often located in close geographic proximity. Co-location rules can be identified by spatial statistics or data mining approaches. In data mining method, Association rule-based approaches can be used which are further divided into transaction-based approaches and distance-based approaches. Transaction-based approaches focus on defining transactions over space so that an Apriori algorithm can be used. The natural notion of transactions is absent in spatial data sets which are embedded in continuous geographic space. A new distance -based approach is developed to mine co-location patterns from spatial data by using the concept of proximity neighborhood. A new interest measure, a participation index, is used for spatial co-location patterns as it possesses an anti-monotone property. An algorithm to discover co-location patterns are designed which generates candidate locations and their table instances. Finally the co-location rules are generated to identify the patterns.
description: 9 pages
Nature and symmetry of the order parameter of the noncentrosymmetric superconductor Li2Pt3B
Creators: name: Mukherjee, Soumya P.
name: Takimoto, Tetsuya
Publisher: name: arXiv
Year: 2011
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: FOS: Physical sciences

description: The nature and symmetry of the superconducting gap function in the noncentrosymmetric superconductor (NCS) Li2Pt3B, even many years after its discovery, appears to be full of contradictions. In this letter based on the existing band structure calculations we find that owing to the considerable nesting near the Fermi surface and the enhanced d-character of the relevant bands that cross the Fermi level,the system gets somewhat strongly correlated. Considering the effect of the onsite Coulomb repulsion on the pairing potential perturbatively, we extract possible superconducting transition. The strong normal spin fluctuation gives rise to a singlet dominant gap function with accompanying sign change. Thus our theory predicts a $s_\pm$ wave gap function with line nodes as the most promising candidate in the superconducting state.
description: 9 pages 4 figures