cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
High Temperature Superconductivity in the Candidate Phases of Solid Hydrogen
Creators: name: Dogan, Mehmet
name: Oh, Sehoon
name: Cohen, Marvin L.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: As the simplest element in nature, unraveling the phase diagram of hydrogen is a primary task for condensed matter physics. As conjectured many decades ago, in the low-temperature and high-pressure part of the phase diagram, solid hydrogen is expected to become metallic with a high superconducting transition temperature. The metallization may occur via band gap closure in the molecular solid or via a transition to the atomic solid. Recently, a few experimental studies pushed the achievable pressures into the 400 - 500 GPa range. There are strong indications that at some pressure in this range metallization via either of these mechanisms occurs, although there are disagreements between experimental reports. Furthermore, there are multiple good candidate crystal phases that have emerged from recent computational and experimental studies which may be realized in upcoming experiments. Therefore, it is crucial to determine the superconducting properties of these candidate phases. In a recent study, we reported the superconducting properties of the C2/c-24 phase, which we believe to be a strong candidate for metallization via band gap closure [M. Dogan et al., arXiv:2107.03889 (2021)]. Here, we report the superconducting properties of the Cmca-12, Cmca-4 and I41/amd-2 phases including the anharmonic effects using a Wannier function-based dense k-point and q-point sampling. We find that the Cmca-12 phase has a superconducting transition temperature that rises from 86 K at 400 GPa to 212 K at 500 GPa, whereas the Cmca-4 and I41/amd-2 phases show a less pressure-dependent behavior with their Tc in the 74 - 94 K and 307 - 343 K ranges, respectively. These properties can be used to distinguish between crystal phases in future experiments. Understanding superconductivity in pure hydrogen is also important in the study of high-Tc hydrides.
Deformation cones of graph associahedra and nestohedra
Creators: name: Padrol, Arnau
name: Pilaud, Vincent
name: Poullot, Germain
Publisher: name: arXiv
Year: 2021
Subjects: subject: Combinatorics (math.CO)
subject: FOS: Mathematics
subject: 52B11, 52B12, 52B35, 05E45

description: We give the facet description of the deformation cones of graph associahedra and nestohedra, generalizing the classical parametrization of the family of deformed permutahedra by the cone of submodular functions. When the underlying building set is made of intervals, this leads in particular to the construction of kinematic nestohedra generalizing the kinematic associahedra that recently appeared in the theory of scattering amplitudes.
description: 27 pages, 10 figures. Section 2 is adapted from Section 2.4 of arXiv:1906.06861v2 (and will disappear there)
Qudit States in Noisy Quantum Channels
Creators: name: Dutta, Supriyo
name: Banerjee, Subhashish
name: Rani, Monika
Publisher: name: arXiv
Year: 2021
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: In this work, we analyze a number of noisy quantum channels on a family of qudit states. The channels studied are the dit-flip noise, phase flip noise, dit-phase flip noise, depolarizing noise, non-Markovian Amplitude Damping Channel (ADC), dephasing noise, and depolarization noise. To gauge the effect of noise, the fidelity between the original and the final states is studied. The change of coherence under the action of noisy channels is also studied, both analytically and numerically. Our approach is advantageous as it has an explicit relation to the original approach to the multi-qubit hypergraph states.
description: This is an updated version of our article "Quantum Hypergraph States in Noisy Quantum Channels". Also, it is a preprint of its published version
Fast manipulation of Bose-Einstein condensates with an atom chip
Creators: name: Corgier, R.
name: Amri, S.
name: Herr, W.
name: Ahlers, H.
name: Rudolph, J.
name: Guéry-Odelin, D.
name: Rasel, Ernst Maria
name: Charron, E.
name: Gaaloul, Naceur
Publisher: name: Bristol : Institute of Physics Publishing
Year: 2018
Subjects: subject: atom chip
subject: atom interferometry
subject: Bose-Einstein condensate
subject: delta-kick collimation
subject: shortcut-to-adiabaticity
subject: Bose-Einstein condensation
subject: Interferometry
subject: Quantum chemistry
subject: Quantum theory
subject: Statistical mechanics
subject: Adiabaticity
subject: Atom chips
subject: Atom interferometry
subject: Bose-Einstein condensates
subject: Atoms
subject: Dewey Decimal Classification::500 | Naturwissenschaften::530 | Physik

description: We present a detailed theoretical analysis of the implementation of shortcut-to-adiabaticity protocols for the fast transport of neutral atoms with atom chips. The objective is to engineer transport ramps with durations not exceeding a few hundred milliseconds to provide metrologically relevant input states for an atomic sensor. Aided by numerical simulations of the classical and quantum dynamics, we study the behavior of a Bose-Einstein condensate in an atom chip setup with realistic anharmonic trapping. We detail the implementation of fast and controlled transports over large distances of several millimeters, i.e. distances 1000 times larger than the size of the atomic cloud. A subsequent optimized release and collimation step demonstrates the capability of our transport method to generate ensembles of quantum gases with expansion speeds in the picokelvin regime. The performance of this procedure is analyzed in terms of collective excitations reflected in residual center of mass and size oscillations of the condensate. We further evaluate the robustness of the protocol against experimental imperfections.
Analysis of the Forward-Backward Trajectory Solution for the Mixed Quantum-Classical Liouville Equation
Creators: name: Hsieh, Chang-Yu
name: Kapral, Raymond
Publisher: name: arXiv
Year: 2013
Subjects: subject: Chemical Physics (physics.chem-ph)
subject: FOS: Physical sciences

description: Mixed quantum-classical methods provide powerful algorithms for the simulation of quantum processes in large and complex systems. The forward-backward trajectory solution of the mixed quantum-classical Liouville equation in the mapping basis [J. Chem. Phys. 137, 22A507 (2012)] is one such scheme. It simulates the dynamics via the propagation of forward and backward trajectories of quantum coherent state variables, and the propagation of bath trajectories on a mean-field potential determined jointly by the forward and backward trajectories. An analysis of the properties of this solution, numerical tests of its validity and an investigation of its utility for the study of nonadiabtic quantum processes are given. In addition, we present an extension of this approximate solution that allows one to systematically improve the results. This extension, termed the jump forward-backward trajectory solution, is analyzed and tested in detail and its various implementations are discussed.
description: 34 pages, 6 figures
Das Hannover Institute of Technology (HITec) der Leibniz Universität : Ideale Bedingungen für Spitzenforschung
Creators: name: Wanner, Alexander
name: Ertmer, Wolfgang
name: Froböse, Tobias
Publisher: name: Hannover : Gottfried Wilhelm Leibniz Universität Hannover
Year: 2018
Subjects: subject: Leibniz Universität Hannover
subject: Forschung
subject: Forschungszentrum
subject: Dewey Decimal Classification::300 | Sozialwissenschaften, Soziologie, Anthropologie::370 | Erziehung, Schul- und Bildungswesen

description: Mit dem Hannover Institute of Technology (HITec) ist im Juli 2018 ein weltweit einmaliges Forschungszentrum in Betrieb gegangen. Unter Beteiligung der Fachgebiete Physik, Geodäsie und Ingenieurwissenschaften soll hier Grundlagenforschung, angewandte Forschung sowie Technologieentwicklung betrieben werden. Der Technische Leiter und der Geschäftsführer des HITec haben den Entstehungsprozess begleitet.
Supplementary results and maps from A secure future? Human urban and agricultural land use benefits a flightless island-endemic rail despite climate change
Creators: name: Lévêque, Lucile
name: Amin, Rahil J.
name: Buettel, Jessie
name: Carver, Scott
name: Brook, Barry
Publisher: name: The Royal Society
Year: 2023
Subjects: subject: Ecology
subject: FOS: Biological sciences

description: Identifying environmental characteristics that limit species' distributions is important for contemporary conservation and inferring responses to future environmental change. The Tasmanian native hen is an island endemic flightless rail and a survivor of a prehistoric extirpation event. Little is known about the regional-scale environmental characteristics influencing the distribution of native hens, or how their future distribution might be impacted by environmental shifts (e.g. climate change). Using a combination of local fieldwork and species distribution modelling, we assess environmental factors shaping the contemporary distribution of the native hen, and project future distribution changes under predicted climate change. We find 37.2% of Tasmania is currently suitable for the native hens, owing to low summer precipitation, low elevation, human-modified vegetation and urban areas. Moreover, in unsuitable regions, urban areas can create ‘oases’ of habitat, able to support populations with high breeding activity by providing resources and buffering against environmental constraints. Under climate change predictions, native hens were predicted to lose only 5% of their occupied range by 2055. We conclude that the species is resilient to climate change and benefits overall from anthropogenic landscape modifications. As such, this constitutes a rare example of a flightless rail to have adapted to human activity.
A two-step energy injection explanation for the rebrightenings of the multi-band afterglow of GRB 081029
Creators: name: Yu, Yongbo
name: Huang, Yongfeng
Publisher: name: arXiv
Year: 2013
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: The afterglow of GRB 081029 showed unusual behavior, with a significant rebrightening being observed at optical wavelength at about 3000 s after the burst. One possible explanation is that the rebrightening is resulted from energy injection. Here, we present a detailed numerical study of the energy injection process and interpret the X-ray and optical afterglow light curves of GRB 081029. In our model, we have assumed two periods of energy injection, each with a constant injection power. One injection starts at $2.8\times10^{3}$ s and lasts for about 2500 s, with a power of $7.0\times10^{47}$ ${\rm erg}$ ${\rm s^{-1}}$. This energy injection is mainly engaged to account for the rapid rebrightening at about 3000 s. The other injection starts at $8.0\times10^{3}$ s and lasts for about 5000 s. The injection power is $3.5\times10^{47}$ ${\rm erg}$ ${\rm s^{-1}}$. This energy injection can help to explain the slight rebrightening at about 10000 s. It is shown that the observed optical afterglow, especially the marked rebrightening at about 3000 s, can be well reproduced. In X-ray band, the predicted amplitude of the rebrightening is much shallower, which is also consistent with the observed X-ray afterglow light curve. It is argued that the two periods of energy injection can be produced by the falling of clumpy materials onto the central compact object of the burster, which leads to an enhancement of accretion and gives birth to a strong outflow temporarily.
description: 10 pages, 2 figures
Sub-Doppler optical resolution by confining a vapour in a nanostructure
Creators: name: Ballin, Philippe
name: Moufarej, Elias
name: Maurin, Isabelle
name: Laliotis, Athanasios
name: Bloch, Daniel
Publisher: name: arXiv
Year: 2013
Subjects: subject: Atomic Physics (physics.atom-ph)
subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: We show that a thermal vapor confined in a nanostructure is of spectroscopic interest. We perform reflection spectroscopy on a Cs vapour cell whose window is covered with a thin opal film (typically, 10 or 20 layers of ~ 1μm diameter spheres). Sub-Doppler structures appear in the optical spectrum in a purely linear regime of optical excitation and the signal is shown to originate from the interstitial regions of the opal. These narrow spectral structures, observable for a large range of oblique incidence angles (~ 30-50°), are an original feature associated to the 3-D vapor confinement. It remembers a Dicke narrowing, i.e. a Doppler broadening suppression when the atomic motion is sub-wavelength confined. This narrowing, commonly observed in the r.f. domain when a buffer gas ensures a collision confinement effect, had remained elusive in the optical frequency. Also, we describe preliminary experiments performed in a pump-probe technique, intended to elucidate the spatial origin of the narrow contribution. We finally discuss how our results allow envisioning micron-size references for optical frequency clocks, and high resolution spectroscopy of weak and hard-to-saturate molecular lines.
Der Einstein-Elevator : Der weltweit erste Fallturm neuer Generation mit hoher Wiederholrate
Creators: name: Overmeyer, Ludger
name: Lazar, Sebastian
name: Lotz, Christoph
Publisher: name: Hannover : Gottfried Wilhelm Leibniz Universität Hannover
Year: 2018
Subjects: subject: Experiment
subject: Gravitation
subject: Dewey Decimal Classification::500 | Naturwissenschaften::530 | Physik

description: Der Einstein-Elevator ist die weltweit erste Forschungseinrichtung für physikalische und produktionstechnische Experimente bei unterschiedlichen Gravitationsbedingungen von Schwerelosigkeit bis zur fünffachen Erdbeschleunigung mit hoher Wiederholrate. Wissenschaftler vom Institut für Transport- und Automatisierungstechnik stellen die Funktionen und einzigartigen Möglichkeiten der Eigenkonstruktion vor.
Spatio-temporal modelling of phenotypic heterogeneity in tumour tissues and its impact on radiotherapy treatment
Creators: name: Celora, Giulia L.
name: Byrne, Helen M.
name: Kevrekidis, P. G.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Cell Behavior (q-bio.CB)
subject: Pattern Formation and Solitons (nlin.PS)
subject: Biological Physics (physics.bio-ph)
subject: FOS: Biological sciences
subject: FOS: Physical sciences

description: We present a mathematical model that describes how tumour heterogeneity evolves in a tissue slice that is oxygenated by a single blood vessel. Phenotype is identified with the stemness level of a cell, $s$, that determines its proliferative capacity, apoptosis propensity and response to treatment. Our study is based on numerical bifurcation analysis and dynamical simulations of a system of coupled non-local (in phenotypic space) partial differential equations that links the phenotypic evolution of the tumour cells to local oxygen levels in the tissue. In our formulation, we consider a 1D geometry where oxygen is supplied by a blood vessel located on the domain boundary and consumed by the tumour cells as it diffuses through the tissue. For biologically relevant parameter values, the system exhibits multiple steady states; in particular, depending on the initial conditions, the tumour is either eliminated ("tumour-extinction") or it persists ("tumour-invasion"). We conclude by using the model to investigate tumour responses to radiotherapy (RT), and focus on establishing which RT strategies can eliminate the tumour. Numerical simulations reveal how phenotypic heterogeneity evolves during treatment and highlight the critical role of tissue oxygen levels on the efficacy of radiation protocols that are commonly used clinically.
Optimal antibunching in passive photonic devices based on coupled nonlinear resonators
Creators: name: Ferretti, S.
name: Savona, V.
name: Gerace, D.
Publisher: name: arXiv
Year: 2012
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Optics (physics.optics)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We propose the use of weakly nonlinear passive materials for prospective applications in integrated quantum photonics. It is shown that strong enhancement of native optical nonlinearities by electromagnetic field confinement in photonic crystal resonators can lead to single-photon generation only exploiting the quantum interference of two coupled modes and the effect of photon blockade under resonant coherent driving. For realistic system parameters in state of the art microcavities, the efficiency of such single-photon source is theoretically characterized by means of the second-order correlation function at zero time delay as the main figure of merit, where major sources of loss and decoherence are taken into account within a standard master equation treatment. These results could stimulate the realization of integrated quantum photonic devices based on non-resonant material media, fully integrable with current semiconductor technology and matching the relevant telecom band operational wavelengths, as an alternative to single-photon nonlinear devices based on cavity-QED with artificial atoms or single atomic-like emitters.
description: to appear in New J. Physics
The Effects of Inhomogeneities within Colliding Flows on the Formation and Evolution of Molecular Clouds
Creators: name: Carroll-Nellenback, Jonathan
name: Frank, Adam
name: Heitsch, Fabian
Publisher: name: arXiv
Year: 2013
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: Observational evidence from local star-forming regions mandates that star formation occurs shortly after, or even during, molecular cloud formation. Models of the formation of molecular clouds in large-scale converging flows have identified the physical mechanisms driving the necessary rapid fragmentation. They also point to global gravitational collapse driving supersonic turbulence in molecular clouds. Previous cloud formation models have focused on turbulence generation, gravitational collapse, magnetic fields, and feedback. Here, we explore the effect of structure in the flow on the resulting clouds and the ensuing gravitational collapse. We compare two extreme cases, one with a collision between two smooth streams, and one with streams containing small clumps. We find that structured converging flows lead to a delay of local gravitational collapse ("star formation"). Thus, more gas has time to accumulate, eventually leading to a strong global collapse, and thus to a high star formation rate. Uniform converging flows fragment hydrodynamically early on, leading to the rapid onset of local gravitational collapse and an overall low sink formation rate.
description: Submitted to ApJ
Passive and hybrid mode locking in multi-section terahertz quantum cascade lasers
Creators: name: Tzenov, P.
name: Babushkin, I.
name: Arkhipov, R.
name: Arkhipov, M.
name: Rosanov, N.
name: Morgner, Uwe
name: Jirauschek, C.
Publisher: name: Bristol : Institute of Physics Publishing
Year: 2018
Subjects: subject: hybrid mode locking
subject: passive mode locking
subject: quantum cascade lasers
subject: Mode-locked fiber lasers
subject: Quantum cascade lasers
subject: Relaxation time
subject: Carrier relaxation time
subject: Colliding pulse modelocking
subject: Hybrid mode-locking
subject: Quantum cascade lasers (QCLs)
subject: Terahertz frequencies
subject: Terahertz quantum-cascade lasers
subject: THz quantum cascade lasers
subject: Ultrashort pulse generation
subject: Passive mode locking
subject: Dewey Decimal Classification::500 | Naturwissenschaften::530 | Physik

description: It is believed that passive mode locking is virtually impossible in quantum cascade lasers (QCLs) because of too fast carrier relaxation time. Here, we revisit this possibility and theoretically show that stable mode locking and pulse durations in the few cycle regime at terahertz (THz) frequencies are possible in suitably engineered bound-to-continuum QCLs. We achieve this by utilizing a multi-section cavity geometry with alternating gain and absorber sections. The critical ingredients are the very strong coupling of the absorber to both field and environment as well as a fast absorber carrier recovery dynamics. Under these conditions, even if the gain relaxation time is several times faster than the cavity round trip time, generation of few-cycle pulses is feasible. We investigate three different approaches for ultrashort pulse generation via THz quantum cascade lasers, namely passive, hybrid and colliding pulse mode locking.
Iris pseudacorus L.
Creators: name: Becherer
Publisher: name: Zenodo
Year: 1956
Subjects: Biodiversity
Taxonomy

description: I. Pseudacorus L. Cat. 343. l: Les Marecottes (Coquoz). - 2: Saillon (J.). - 3: Riddes-Bieudron (J.).
description: Published as part of Becherer, 1956, Florae Vallesiacae Supplementum, pp. 1-556 in Denkschriften der Schweizerischen Naturforschenden Gesellschaft 71 on pages 1-556
Mehr als nur Lichtleitung : Innovative Glasfaserherstellung am HITec
Creators: name: Ristau, Detlev
name: Rühl, Axel
name: Ließmann, Matthias
Publisher: name: Hannover : Gottfried Wilhelm Leibniz Universität Hannover
Year: 2018
Subjects: subject: Glasfaser
subject: Spezialfaser
subject: Optischer Wellenleiter
subject: Dewey Decimal Classification::500 | Naturwissenschaften::530 | Physik

description: In den Laboratorien des HITec-Gebäudes können aufgrund der technischen Ausstattung in Zukunft neuartige, laseraktive und strahlungsharte Fasern realisiert werden. Wissenschaftler vom Institut für Quantenoptik und vom Laser Zentrum Hannover e.V. berichten über die Verbindung der klassischen Forschung an laseraktiven Glasfasern mit Weltraumanwendungen. Ziel dabei ist es, ein Forschungszentrum für die Herstellung von Spezialfasern zu etablieren.
Stellar outbursts and chondrite composition
Creators: name: Li, Min
name: Zhu, Zhaohuan
name: Huang, Shichun
name: Sui, Ning
name: Petaev, Michail I.
name: Steffen, Jason H.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: The temperatures of observed protoplanetary disks are not sufficiently high to produce the accretion rate needed to form stars, nor are they sufficient to explain the volatile depletion patterns in CM, CO, and CV chondrites and terrestrial planets. We revisit the role that stellar outbursts, caused by high accretion episodes, play in resolving these two issues. These outbursts provide the necessary mass to form the star during the disk lifetime, and provide enough heat to vaporize planet-forming materials. We show that these outbursts can reproduce the observed chondrite abundances at distances near one AU. These outbursts would also affect the growth of calcium-aluminum-rich inclusions (CAIs) and the isotopic compositions of carbonaceous and non-carbonaceous chondrites.
description: 20 pages, 13 figures, accepted to ApJ
In Situ Measurements of the Size and Density of Titan Aerosol Analogues
Creators: name: Horst, Sarah M.
name: Tolbert, Margaret A.
Publisher: name: arXiv
Year: 2013
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: FOS: Physical sciences

description: The organic haze produced from complex CH4/N2 chemistry in the atmosphere of Titan plays an important role in processes that occur in the atmosphere and on its surface. The haze particles act as condensation nuclei and are therefore involved in Titan's methane hydrological cycle. They also may behave like sediment on Titan's surface and participate in both fluvial and aeolian processes. Models that seek to understand these processes require information about the physical properties of the particles including their size and density. Although measurements obtained by Cassini-Huygens have placed constraints on the size of the haze particles, their densities remain unknown. We have conducted a series of Titan atmosphere simulation experiments and measured the size, number density, and particle density of Titan aerosol analogues, or tholins, for CH4 concentrations from 0.01% to 10% using two different energy sources, spark discharge and UV. We find that the densities currently in use by many Titan models are higher than the measured densities of our tholins.
description: 21 pages, 3 figures, 2 tables. Accepted in Astrophysical Journal Letters
Extremizers for Adjoint Restriction to Pairs of Translated Paraboloids
Creators: name: Tautges, James
Publisher: name: arXiv
Year: 2021
Subjects: subject: Classical Analysis and ODEs (math.CA)
subject: Analysis of PDEs (math.AP)
subject: FOS: Mathematics
subject: 42

description: Consider the adjoint restriction inequality associated with the hypersurface $\{ (τ, ξ) \in \mathbb{R}^{d+1} : τ= |ξ|^2 \} \cup \{(τ, ξ) \in \mathbb{R}^{d+1} : τ- τ_0 = |ξ- ξ_0|^2\}$ for any $(τ_0, ξ_0) \neq 0$. We prove that extremizers do not exist for this inequality and fully characterize extremizing sequences in terms of extremizers for the adjoint restriction inequality for the paraboloid.
Das HITec als Herzstück : Geodäsie und Quantenphysik verbinden sich
Creators: name: Timmen, Ludger
name: Kersten, Tobias
name: Müller, Jürgen
name: Schilling, Manuel
name: Schön, Steffen
name: Paffenholz, Jens-André
name: Neumann, Ingo
Publisher: name: Hannover : Gottfried Wilhelm Leibniz Universität Hannover
Year: 2018
Subjects: subject: Gravimetrie
subject: Schweremessung
subject: Geodäsie
subject: Dewey Decimal Classification::500 | Naturwissenschaften::550 | Geowissenschaften
subject: Dewey Decimal Classification::500 | Naturwissenschaften::530 | Physik

description: Das HITec ist für die Wissenschaft der Geodäsie und der Physik eine weltweit einzigartige Laborumgebung. Dort soll durch die Simulation verschiedenster Umweltbedingungen die Entwicklung von MultiSensorSystemen (MSS) der nächsten Generation praktisch realisiert werden. Forscherteams vom Institut für Erdmessung (IfE) und dem Geodätischen Institut Hannover (GIH) berichten.
The canonical complex of the weak order
Creators: name: Albertin, Doriann
name: Pilaud, Vincent
Publisher: name: arXiv
Year: 2021
Subjects: subject: Combinatorics (math.CO)
subject: FOS: Mathematics
subject: 06A07, 06B05, 06B10

description: We define and study the canonical complex of a finite semidistributive lattice $L$. It is the simplicial complex on the join or meet irreducible elements of $L$ which encodes each interval of $L$ by recording the canonical join representation of its bottom element and the canonical meet representation of its top element. This complex behaves properly with respect to lattice quotients of $L$, in the sense that the canonical complex of a quotient of $L$ is the subcomplex of the canonical complex of $L$ induced by the join or meet irreducibles of $L$ uncontracted in the quotient. We then describe combinatorially the canonical complex of the weak order on permutations in terms of semi-crossing arc bidiagrams, formed by the superimposition of two non-crossing arc diagrams of N. Reading. We provide explicit direct bijections between the semi-crossing arc bidiagrams and the weak order interval posets of G. Châtel, V. Pilaud and V. Pons. Finally, we provide an algorithm to describe the Kreweras maps in any lattice quotient of the weak order in terms of semi-crossing arc bidiagrams.
description: 18 pages, 12 figures; Version 2: minor corrections
Transforming encounters: A review of the drivers and mechanisms of macrofaunal plastic fragmentation in the environment
Creators: name: Rambacher, Julia
name: Pantos, Olga
name: Hardwick, Scott
name: Cameron, Elissa Z.
name: Gaw, Sally
Publisher: name: AgResearch
Year: 2023
Subjects: Environmental management
Pollution and contamination

description: Plastic has infiltrated every ecosystem on the planet, making encounters between this anthropogenic pollutant and fauna inevitable. Abiotic environmental breakdown involving light, oxygen, temperature and mechanical forces is well-characterized, while biotic degradation mechanisms are less well-understood. Reports of the role of macrofauna in the fragmentation of plastic debris are increasing. This review explores the driving factors for macrofaunal fragmentation, as well as the physiological mechanisms by which plastic items are fragmented. The presence, and access to plastic within an organism’s habitat are the key determinants of macrofaunal plastic degradation. Foraging strategies, along with burrowing and nesting behaviors increase the likelihood of macrofauna interacting with plastics. Though this type of fragmentation can occur externally, it often follows ingestion, which in itself can be driven by resemblance to food. Four physical mechanisms of macrofaunal plastic fragmentation were identified, namely biting, drilling, grazing and grinding. Biting, restricted to the mouthparts of an organism, was the most common form of macrofaunal fragmentation reported in literature. Similarly, the use of specialized mouthparts for drilling or grazing can produce secondary plastic particles. Lastly, grinding, through manipulation by the gizzard or gastric mill following ingestion can significantly reduce the size of the plastic material. Prolonged and/or repeated interactions with plastics pose the risk of increased wear on the mouthparts and digestive organs involved. Through mechanisms that directly affect the plastic’s structural integrity, physical fragmentation by macrofauna can amplify overall plastic degradation rates and the formation of micro- and nanoplastics in the environment, while long internal retention times can contribute to their dispersal, trophic transfer, and the organism’s exposure to plastic additives. To more fully understand the extent of macrofaunal plastic fragmentation and allow predictive modeling, we suggest the reporting of evidence in a unified and systematic way. Our findings further highlight the urgency for the implementation of a global plastic waste management system to reduce the burden of micro- and nanoplastics.
A Convex-Nonconvex Strategy for Grouped Variable Selection
Creators: name: Liu, Xiaoqian
name: Molstad, Aaron J.
name: Chi, Eric C.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Methodology (stat.ME)
subject: FOS: Computer and information sciences

description: This paper deals with the grouped variable selection problem. A widely used strategy is to augment the negative log-likelihood function with a sparsity-promoting penalty. Existing methods include the group Lasso, group SCAD, and group MCP. The group Lasso solves a convex optimization problem but is plagued by underestimation bias. The group SCAD and group MCP avoid this estimation bias but require solving a nonconvex optimization problem that may be plagued by suboptimal local optima. In this work, we propose an alternative method based on the generalized minimax concave (GMC) penalty, which is a folded concave penalty that maintains the convexity of the objective function. We develop a new method for grouped variable selection in linear regression, the group GMC, that generalizes the strategy of the original GMC estimator. We present an efficient algorithm for computing the group GMC estimator and also prove properties of the solution path to guide its numerical computation and tuning parameter selection in practice. We establish error bounds for both the group GMC and original GMC estimators. A rich set of simulation studies and a real data application indicate that the proposed group GMC approach outperforms existing methods in several different aspects under a wide array of scenarios.
description: 34 pages, 4 figures
X-ray source variability study of the M 31 central field using Chandra HRC-I
Creators: name: Hofmann, F.
name: Pietsch, W.
name: Henze, M.
name: Haberl, F.
name: Sturm, R.
name: Della Valle, M.
name: Hartmann, D. H.
name: Hatzidimitriou, D.
Publisher: name: arXiv
Year: 2013
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: [Abridged] The central field of the Andromeda galaxy (M 31) has been monitored, using the Chandra HRC-I detector (about 0.1-10 keV energy range) from 2006 to 2012 with the main aim to detect X-rays from optical novae. We present a systematic analysis of all X-ray sources found in the 41 nova monitoring observations, along with 23 M 31 central field HRC-I observations available from the Chandra data archive starting in December 1999. Based on these observations, we studied the X-ray long-term variability of the source population and especially of X-ray binaries in M 31. We created a catalogue of sources, detected in the 64 available observations, which add up to a total exposure of about 1 Ms. We present a point-source catalogue, containing 318 X-ray sources with detailed long-term variability information, 28 of which are published for the first time. The spatial and temporal resolution of the catalogue allows us to classify 115 X-ray binary candidates showing high X-ray variability or even outbursts in addition to 14 globular cluster X-ray binary candidates showing no significant variability. The analysis may suggest, that outburst sources are less frequent in globular clusters than in the field of M 31. We detected 7 supernova remnants, one of which is a new candidate and in addition resolved the first X-rays from a known radio supernova remnant. Besides 33 known optical nova/X-ray source correlations, we also discovered one previously unknown super-soft X-ray outburst and several new nova candidates. The catalogue contains a large sample of detailed long-term X-ray light curves in the M 31 central field, which helps to understand the X-ray population of our neighbouring spiral galaxy M 31.
description: 51 pages, 17 figures, 9 tables, submitted to Astronomy and Astrophysics
Detection of slow atoms confined in a Cesium vapor cell by spatially separated pump and probe laser beams
Creators: name: Todorov, Petko
name: Petrov, Nikoolay
name: Maurin, Isabelle
name: Saltiel, Solomon
name: Bloch, Daniel
Publisher: name: arXiv
Year: 2013
Subjects: subject: Atomic Physics (physics.atom-ph)
subject: FOS: Physical sciences

description: The velocity distribution of atoms in a thermal gas is usually described through a Maxwell-Boltzman distribution of energy, and assumes isotropy. As a consequence, the probability for an atom to leave the surface under an azimuth angle θ should evolve as cos θ, in spite of the fact that there is no microscopic basis to justify such a law. The contribution of atoms moving at a grazing incidence towards or from the surface, i.e. atoms with a small normal velocity, here called "slow" atoms, reveals essential in the development of spectroscopic methods probing a dilute atomic vapor in the vicinity of a surface, enabling a sub-Doppler resolution under a normal incidence irradiation. The probability for such "slow" atoms may be reduced by surface roughness and atom-surface interaction. Here, we describe a method to observe and to count these slow atoms relying on a mechanical discrimination, through spatially separated pump and probe beams. We also report on our experimental progresses toward such a goal.
description: proceedings of 17th International School on Quantum Electronics: Laser Physics and Applications, neesebar, bulgaria Sept 2012 edited by Tanja Dreischuh, Albena Daskalova
GC/MS Analysis of Some Bioactive Constituents from Carthamus lanatus L.
Creators: name: Mitova, Maya
name: Taskova, Rilka M.
name: Popov, Simeon
name: Berger, Ralf Günter
name: Krings, Ulrich
name: Handjieva, Nedjalka
Publisher: name: Berlin : De Gruyter
Year: 2003
Subjects: subject: Carthamus lanatus
subject: Cytotoxic Activity
subject: GC/MS Analysis
subject: Animals
subject: Artemia
subject: Carthamus
subject: Cell Survival
subject: Flowers
subject: Gas Chromatography-Mass Spectrometry
subject: Mediterranean Region
subject: Plant Components, Aerial
subject: Plants, Medicinal
subject: Sterols
subject: Triterpenes
subject: Artemia salina
subject: Salina
subject: Salina beta
subject: Dewey Decimal Classification::500 | Naturwissenschaften::570 | Biowissenschaften, Biologie

description: Sterols, triterpenes, volatiles, polar and other constituents in aerial parts of Carthamus lanatus were analyzed by gas chromatography-mass spectrometry. Over 90 compounds were identified most of them new for the species. Sitosterol and stigmasterol were the most abundant of 10 sterols identified in the sterol fraction. Taraxasterol, α- and β-amyrine prevailed in the triterpene fraction. Volatiles, sterols and a fraction of the dichloromethane extract showed strong cytotoxicity (Artemia salina assay).
A new type of nuclear collective motion - the spin scissors mode
Creators: name: Balbutsev, E. B.
name: Molodtsova, I. V.
name: Schuck, P.
Publisher: name: arXiv
Year: 2013
Subjects: subject: Nuclear Theory (nucl-th)
subject: FOS: Physical sciences

description: The coupled dynamics of low lying modes and various giant resonances are studied with the help of the Wigner Function Moments method on the basis of Time Dependent Hartree-Fock equations in the harmonic oscillator model including spin-orbit potential plus quadrupole-quadrupole and spin-spin residual interactions. New low lying spin dependent modes are analyzed. Special attention is paid to the spin scissors mode.
description: 21 pages
Monitoring and Adapting the Physical State of a Camera for Autonomous Vehicles
Creators: name: Wischow, Maik
name: Gallego, Guillermo
name: Ernst, Ines
name: Börner, Anko
Publisher: name: arXiv
Year: 2021
Subjects: subject: Computer Vision and Pattern Recognition (cs.CV)
subject: Image and Video Processing (eess.IV)
subject: FOS: Computer and information sciences
subject: FOS: Electrical engineering, electronic engineering, information engineering

description: Autonomous vehicles and robots require increasingly more robustness and reliability to meet the demands of modern tasks. These requirements specially apply to cameras onboard such vehicles because they are the predominant sensors to acquire information about the environment and support actions. Cameras must maintain proper functionality and take automatic countermeasures if necessary. Existing solutions are typically tailored to specific problems or detached from the downstream computer vision tasks of the machines, which, however, determine the requirements on the quality of the produced camera images. We propose a generic and task-oriented self-health-maintenance framework for cameras based on data- and physically-grounded models. To this end, we determine two reliable, real-time capable estimators for typical image effects of a camera in poor condition (blur, noise phenomena and most common combinations) by evaluating traditional and customized machine learning-based approaches in extensive experiments. Furthermore, we implement the framework on a real-world ground vehicle and demonstrate how a camera can adjust its parameters to counter an identified poor condition to achieve optimal application capability based on experimental (non-linear and non-monotonic) input-output performance curves. Object detection is chosen as target application, and the image effects motion blur and sensor noise as conditioning examples. Our framework not only provides a practical ready-to-use solution to monitor and maintain the health of cameras, but can also serve as a basis for extensions to tackle more sophisticated problems that combine additional data sources (e.g., sensor or environment parameters) empirically in order to attain fully reliable and robust machines. Code: https://github.com/MaikWischow/Camera-Condition-Monitoring
description: 17 pages, 20 figures, https://github.com/MaikWischow/Camera-Condition-Monitoring
Vom All aus : Ein weltraumbasiertes Laserinterferometer vermisst das Erdschwerefeld
Creators: name: Mehmet, Moritz
name: Gerberding, Oliver
name: Müller, Vitali
name: Händchen, Vitus
name: Isleif, Katharina-Sophie
Publisher: name: Hannover : Gottfried Wilhelm Leibniz Universität Hannover
Year: 2018
Subjects: subject: Schwerefeld
subject: GRACE
subject: Gravimetrie
subject: Dewey Decimal Classification::500 | Naturwissenschaften::530 | Physik

description: GRACE Follow-On ist eine gravi - metrische Weltraummission, mit der anhand eines Satellitenpaares das Erdschwerefeld vermessen wird. Die monatlichen Karten des Erdschwerefelds, die aus den Daten von GRACE konstruiert werden, haben sich als wichtiges Werkzeug für Klima- und Geowissenschaftler etabliert. Ein Forschungsteam vom Institut für Gravitationsphysik stellt die Entwicklung neuer Sensoren für die Satellitengravimetrie vor.
Determinanten und Effekte von Auslandsmobilität im Studium
Creators: name: Netz, Nicolai
Publisher: name: Hannover : Gottfried Wilhelm Leibniz Universität Hannover
Year: 2018
Subjects: subject: Studienbezogene Auslandsmobilität
subject: Determinanten
subject: erwerbsbezogene Effekte
subject: Dewey Decimal Classification::300 | Sozialwissenschaften, Soziologie, Anthropologie::370 | Erziehung, Schul- und Bildungswesen

description: [no abstract]
Juniperus sibirica
Creators: name: Becherer
Publisher: name: Zenodo
Year: 1956
Subjects: Biodiversity
Taxonomy

description: I. sibirica L. l: Monthey, nahe der Einmündung der Viezein die Rhone (Defago 1936). Fundort heute durch Trockenlegung vernichtet. Verwildert wurden ferner früherbeobachtet: I.pumila L. und I. pallida Lam. (Cat. L und 343).
description: Published as part of Becherer, 1956, Florae Vallesiacae Supplementum, pp. 1-556 in Denkschriften der Schweizerischen Naturforschenden Gesellschaft 71 on pages 1-556
Ultra-high-ohmic microstripline resistors for Coulomb blockade devices
Creators: name: Lotkhov, Sergey V
Publisher: name: arXiv
Year: 2013
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: In this paper, we report on the fabrication and the low-temperature characterization of extremely high-ohmic microstrip resistors made of a thin film of weakly oxidized titanium. Nearly linear voltage-current characteristics were measured at temperatures down to $T \sim \unit[20]{mK}$ for films with sheet resistivity up to as high as $\sim \unit[7]{kΩ}$, i.e. about an order of magnitude higher than our previous findings for weakly oxidized Cr. Our analysis indicates that such an improvement can help to create an advantageous high-impedance environment for different Coulomb blockade devices. Further properties of the Ti film addressed in this work show a promise of low-noise behavior of the resistors when applied in different realizations of the quantum standard of current.
description: 8 pages 3 figures
Upper bounds of local electronic densities in molecules
Creators: name: Ashida, Sohei
Publisher: name: arXiv
Year: 2021
Subjects: subject: Mathematical Physics (math-ph)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences
subject: 81V55, 35B45

description: The eigenfunctions of electronic Hamiltonians determine the stable structures and dynamics of molecules through the local distributions of their densities. In this paper an a priori upper bound for such local distributions of the densities is given. The bound means that concentration of electrons is prohibited due to the repulsion between the electrons. A relation between one-electron and two-electron densities resulting from the antisymmetry of the eigenfunctions plays a crucial role in the proof.
Extremizers for Adjoint Restriction to a Pair of Reflected Paraboloids
Creators: name: Tautges, James
Publisher: name: arXiv
Year: 2021
Subjects: subject: Classical Analysis and ODEs (math.CA)
subject: Analysis of PDEs (math.AP)
subject: FOS: Mathematics
subject: 42B

description: We consider the adjoint restriction inequality associated to the hypersurface $\{(τ, ξ) : τ= \pm|ξ|^2, \;ξ\in \mathbb{R}^d\}$ at the Stein-Tomas exponent. Extremizers exist in all dimensions and extremizing sequences are precompact modulo symmetries conditional on a certain inequality, which we verify in the case $d \in \{1,2\}$.
The benefits of completing homework for students with different aptitudes in an introductory physics course
Creators: name: Kontur, F. J.
name: Terry, N. B.
Publisher: name: arXiv
Year: 2013
Subjects: subject: Physics Education (physics.ed-ph)
subject: FOS: Physical sciences

description: We examine the relationship between homework completion and exam performance for students having different physics aptitudes for five different semesters of an introductory electricity and magnetism course. In our analysis, we plot exam scores versus homework completion scores and calculate the slopes of the line fits and the Pearson correlations. On average, completing many homework problems correlated to better exam scores only for students with high physics aptitude. Low aptitude physics students had a negative correlation between exam performance and completing homework; the more homework problems they did, the worse their performance was on exams. One explanation for this effect is that the assigned homework problems placed an excessive cognitive load on low aptitude students. As a result, no learning or even negative learning might have taken place when low aptitude students attempted to do assigned homework. Another explanation is based on the fact that the negative benefit effects first appeared when magnetism concepts were introduced. According to this explanation, low aptitude students had difficulty consolidating knowledge of magnetic fields with previously-learned knowledge of electric fields. A third possibility, that a high homework copying rate by low aptitude students impeded learning, is rejected because two different analyses revealed no evidence of homework copying.
description: 16 pages, 6 figures, 4 tables
Temporal Knowledge Graph Completion: A Survey
Creators: name: Cai, Borui
name: Xiang, Yong
name: Gao, Longxiang
name: Zhang, He
name: Li, Yunfeng
name: Li, Jianxin
Publisher: name: arXiv
Year: 2022
Subjects: subject: Artificial Intelligence (cs.AI)
subject: Machine Learning (cs.LG)
subject: FOS: Computer and information sciences

description: Knowledge graph completion (KGC) can predict missing links and is crucial for real-world knowledge graphs, which widely suffer from incompleteness. KGC methods assume a knowledge graph is static, but that may lead to inaccurate prediction results because many facts in the knowledge graphs change over time. Recently, emerging methods have shown improved predictive results by further incorporating the timestamps of facts; namely, temporal knowledge graph completion (TKGC). With this temporal information, TKGC methods can learn the dynamic evolution of the knowledge graph that KGC methods fail to capture. In this paper, for the first time, we summarize the recent advances in TKGC research. First, we detail the background of TKGC, including the problem definition, benchmark datasets, and evaluation metrics. Then, we summarize existing TKGC methods based on how timestamps of facts are used to capture the temporal dynamics. Finally, we conclude the paper and present future research directions of TKGC.