cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Reflections on the Matter of 3d $\mathcal{N} = 1$ Vacua and Local $Spin(7)$ Compactifications
Creators: name: Cvetič, Mirjam
name: Heckman, Jonathan J.
name: Torres, Ethan
name: Zoccarato, Gianluca
Publisher: name: arXiv
Year: 2021
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: Algebraic Topology (math.AT)
subject: Differential Geometry (math.DG)
subject: FOS: Physical sciences
subject: FOS: Mathematics

description: We use Higgs bundles to study the 3d $\mathcal{N} = 1$ vacua obtained from M-theory compactified on a local $Spin(7)$ space given as a four-manifold $M_4$ of ADE singularities with further generic enhancements in the singularity type along one-dimensional subspaces. There can be strong quantum corrections to the massless degrees of freedom in the low energy effective field theory, but topologically robust quantities such as "parity" anomalies are still calculable. We show how geometric reflections of the compactification space descend to 3d reflections and discrete symmetries. The "parity" anomalies of the effective field theory descend from topological data of the compactification. The geometric perspective also allows us to track various perturbative and non-perturbative corrections to the 3d effective field theory. We also provide some explicit constructions of well-known 3d theories, including those which arise as edge modes of 4d topological insulators, and 3d $\mathcal{N} = 1$ analogs of grand unified theories. An additional result of our analysis is that we are able to track the spectrum of extended objects and their transformations under higher-form symmetries.
description: v3: 85 pages, 4 figures, typos corrected, clarifications added
Stepwise Weakening of the Pliocene Leeuwin Current
Creators: name: De Vleeschouwer, David
name: Petrick, Benjamin F.
name: Martínez-García, Alfredo
Publisher: name: FID GEO
Year: 2019

description: The Indonesian Throughflow (ITF) operates as an important link in global thermohaline circulation, and ITF variability probably modulated Pliocene climate change. Yet, whether ITF variability accounted for oceanographic change south of Northwest Cape remains controversial. Here, we present a multiproxy oceanographic reconstruction from the Perth Basin and reconstruct the Pliocene history of the Leeuwin Current (LC). We show that the LC was active throughout the Pliocene, albeit with fluctuations in intensity and scope. Three main factors controlled LC strength. First, a tectonic ITF reorganization caused an abrupt and permanent LC reduction at 3.7 Ma. On shorter timescales, eustatic sea level and direct orbital forcing of wind patterns hampered or promoted the LC. At 3.3 Ma, for instance, LC intensity plunged in response to a eustatic ITF restriction. Site U1459 then fell outside the extent of a weakened LC, and the latitudinal sea surface temperature gradient along West Australia doubled its steepness.
Is Modified Gravity Required by Observations? An Empirical Consistency Test of Dark Energy Models
Creators: name: Wang, Sheng
name: Hui, Lam
name: May, Morgan
name: Haiman, Zoltan
Publisher: name: arXiv
Year: 2007
Subjects: subject: Astrophysics (astro-ph)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We apply the technique of parameter-splitting to existing cosmological data sets, to check for a generic failure of dark energy models. Given a dark energy parameter, such as the energy density Omega_Lambda or equation of state w, we split it into two meta-parameters with one controlling geometrical distances, and the other controlling the growth of structure. Observational data spanning Type Ia Supernovae, the cosmic microwave background (CMB), galaxy clustering, and weak gravitational lensing statistics are fit without requiring the two meta-parameters to be equal. This technique checks for inconsistency between different data sets, as well as for internal inconsistency within any one data set (e.g., CMB or lensing statistics) that is sensitive to both geometry and growth. We find that the cosmological constant model is consistent with current data. Theories of modified gravity generally predict a relation between growth and geometry that is different from that of general relativity. Parameter-splitting can be viewed as a crude way to parametrize the space of such theories. Our analysis of current data already appears to put sharp limits on these theories: assuming a flat universe, current data constrain the difference Omega_Lambda(geom) - Omega_Lambda(grow) to be -0.0044 +/- 0.0058 (68% C.L.); allowing the equation of state w to vary, the difference w(geom) - w(grow) is constrained to be 0.37 +/- 0.37 (68% C.L.). Interestingly, the region w(grow) > w(geom), which should be generically favored by theories that slow structure formation relative to general relativity, is quite restricted by data already. We find w(grow) < -0.80 at 2 sigma. As an example, the best-fit flat Dvali-Gabadadze-Porrati (DGP) model approximated by our parametrization lies beyond the 3 sigma contour for constraints from all the data sets.
description: 7 pages, 3 figures. v2: constraints on DGP theory added; references added; final version published in Phys. Rev. D
Storm-induced turbulence alters shelf sea vertical fluxes
Creators: name: Schultze, Larissa K. P.
name: Merckelbach, Lucas M.
name: Carpenter, Jeffrey R.
Publisher: name: FID GEO
Year: 2020

description: Storms are infrequent, intense, physical forcing events that represent a potentially significant driver of ocean ecosystems. The objective of this study was to assess changes in water column structure and turbulent fluxes caused by storms using an autonomous underwater glider, as well as the chlorophyll a (Chl a) response to the altered physical environment. The glider was able to measure throughout the complete life cycle of Storm Bertha as it passed over the North Sea in August 2014, from its arrival to dissipation. Storm Bertha triggered rapid mixing of the thermocline through shear instability, increasing vertical fluxes by nearly an order of magnitude, and promoting increases in surface layer Chl a. The results demonstrate that storms represent a significant fraction of seasonal vertical turbulent fluxes, with potentially important consequences for biological production in shelf seas.
Study of the decay Ds+ --> K+ K- e+ nu
Creators: name: The BABAR Collaboration
name: Aubert, B.
Publisher: name: arXiv
Year: 2008
Subjects: subject: High Energy Physics - Experiment (hep-ex)
subject: FOS: Physical sciences

description: Using 214 fb-1 of data recorded by the Babar detector at the PEPII electron-positron collider, we study the decay Ds+ --> K+ K- e+ nu. Except for a small S-wave contribution, the events with K+K- masses in the range 1.01-1.03 GeV/c2 correspond to phi mesons. For Ds+ --> phi e+ nu decays, we measure the relative normalization of the Lorentz invariant form factors at q2=0, rV=V(0)/A1(0)=1.849 +/- 0.060 +/- 0.095, r2=A2(0)/A1(0)=0.763 +/- 0.071 +/- 0.065 and the pol e mass of the axial-vector form factors mA=(2.28^{+0.23}_{-0.18}+/- 0.18) GeV/c2. Within the same K+K- mass range, we also measure the relative branching fraction B(Ds+ --> K + K- e+ nu)/B(Ds+ --> K+ K- pi+)=0.558 +/- 0.007 +/- 0.016, from which we obtain the total branching fraction B(Ds+ --> phi e+ nu) = (2.61 +/- 0.03 +/- 0.08 +/- 0.15)* 10^{-2}. By comparing this value with the predicted decay rate, we extract A1(0) = 0.607 +/- 0.011 +/- 0.019 +/- 0.018. The stated uncertainties are statistical, systematic, and from external inputs.
description: 8 pages, 2 postscript figures, submitted to PRD-RC
Direct observation of high-speed plasma outflows produced by magnetic reconnection in solar impulsive events
Creators: name: Wang, Tongjiang
name: Sui, Linhui
name: Qiu, Jiong
Publisher: name: arXiv
Year: 2007
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: Spectroscopic observations of a solar limb flare recorded by SUMER on SOHO reveal, for the first time, hot fast magnetic reconnection outflows in the corona. As the reconnection site rises across the SUMER spectrometer slit, significant blue- and red-shift signatures are observed in sequence in the Fe XIX line, reflecting upflows and downflows of hot plasma jets, respectively. With the projection effect corrected, the measured outflow speed is between 900-3500 km/s, consistent with theoretical predictions of the Alfvenic outflows in magnetic reconnection region in solar impulsive events. Based on theoretic models, the magnetic field strength near the reconnection region is estimated to be 19-37 Gauss.
description: 5 pages, 6 color figures, 1 animation online
On the Milky Way spiral arms from open clusters in Gaia EDR3
Creators: name: Castro-Ginard, A.
name: McMillan, P. J.
name: Luri, X.
name: Jordi, C.
name: Romero-Gómez, M.
name: Cantat-Gaudin, T.
name: Casamiquela, L.
name: Tarricq, Y.
name: Soubiran, C.
name: Anders, F.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: Context. The physical processes driving the formation of Galactic spiral arms are still under debate. Studies using open clusters favour the description of the Milky Way spiral arms as long-lived structures following the classical density wave theory. Current studies comparing the Gaia DR2 field stars kinematic information of the Solar neighbourhood to simulations, find a better agreement with short-lived arms with a transient behaviour. Aims. Our aim is to provide an observational, data-driven view of the Milky Way spiral structure and its dynamics using open clusters as the main tracers, and to contrast it with simulation-based approaches. We use the most complete catalogue of Milky Way open clusters, with astrometric Gaia EDR3 updated parameters, estimated astrophysical information and radial velocities, to re-visit the nature of the spiral pattern of the Galaxy. Methods. We use a Gaussian mixture model to detect overdensities of open clusters younger than 30 Myr that correspond to the Perseus, Local, Sagittarius and Scutum spiral arms, respectively. We use the birthplaces of the open cluster population younger than 80 Myr to trace the evolution of the different spiral arms and compute their pattern speed. We analyse the age distribution of the open clusters across the spiral arms to explore the differences in the rotational velocity of stars and spiral arms. Results. We are able to increase the range in Galactic azimuth where present-day spiral arms are described, better estimating its parameters by adding 264 young open clusters to the 84 high-mass star-forming regions used so far, thus increasing by a 314% the number of tracers. We use the evolution of the open clusters from their birth positions to find that spiral arms nearly co-rotate with field stars at any given radius, discarding a common spiral pattern speed for the spiral arms explored. [abridged]
description: 9 pages, 7 figures. Accepted for publication in A&A
Dark energy constraints from cosmic shear power spectra: impact of intrinsic alignments on photometric redshift requirements
Creators: name: Bridle, Sarah
name: King, Lindsay
Publisher: name: arXiv
Year: 2007
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: Cosmic shear constrains cosmology by exploiting the apparent alignments of pairs of galaxies due to gravitational lensing by intervening mass clumps. However galaxies may become (intrinsically) aligned with each other, and with nearby mass clumps, during their formation. This effect needs to be disentangled from the cosmic shear signal to place constraints on cosmology. We use the linear intrinsic alignment model as a base and compare it to an alternative model and data. If intrinsic alignments are ignored then the dark energy equation of state is biased by ~50 per cent. We examine how the number of tomographic redshift bins affects uncertainties on cosmological parameters and find that when intrinsic alignments are included two or more times as many bins are required to obtain 80 per cent of the available information. We investigate how the degradation in the dark energy figure of merit depends on the photometric redshift scatter. Previous studies have shown that lensing does not place stringent requirements on the photometric redshift uncertainty, so long as the uncertainty is well known. However, if intrinsic alignments are included the requirements become a factor of three tighter. These results are quite insensitive to the fraction of catastrophic outliers, assuming that this fraction is well known. We show the effect of uncertainties in photometric redshift bias and scatter. Finally we quantify how priors on the intrinsic alignment model would improve dark energy constraints.
description: 14 pages and 9 figures. Replaced with final version accepted in "Gravitational Lensing" Focus Issue of the New Journal of Physics at http://www.iop.org/EJ/abstract/1367-2630/9/12/E09
Proteome remodelling during development from blood to insect-form Trypanosoma brucei quantified by SILAC and mass spectrometry
Creators: name: Gunasekera, Kapila
name: Wüthrich, Daniel
name: Braga-Lagache, Sophie
name: Heller, Manfred
name: Ochsenreiter, Torsten
Publisher: name: arXiv
Year: 2021
Subjects: subject: Quantitative Methods (q-bio.QM)
subject: FOS: Biological sciences

description: Background: Trypanosoma brucei is the causative agent of human African sleeping sickness and Nagana in cattle. In addition to being an important pathogen T. brucei has developed into a model system in cell biology. Results: Using Stable Isotope Labelling of Amino acids in Cell culture (SILAC) in combination with mass spectrometry we determined the abundance of >1600 proteins in the long slender (LS), short stumpy (SS) mammalian bloodstream form stages relative to the procyclic (PC) insect-form stage. In total we identified 2645 proteins, corresponding to ~30% of the total proteome and for the first time present a comprehensive overview of relative protein levels in three life stages of the parasite. Conclusions: We can show the extent of pre-adaptation in the SS cells, especially at the level of the mitochondrial proteome. The comparison to a previously published report on monomorphic in vitro grown bloodstream and procyclic T. brucei indicates a loss of stringent regulation particularly of mitochondrial proteins in these cells when compared to the pleomorphic in vivo situation. In order to better understand the different levels of gene expression regulation in this organism we compared mRNA steady state abundance with the relative protein abundance-changes and detected moderate but significant correlation indicating that trypanosomes possess a significant repertoire of translational and posttranslational mechanisms to regulate protein abundance.
description: 14 pages, 7 figures
Perturbation d'un hamiltonien partiellement hyperbolique
Creators: name: Bernard, Patrick
Publisher: name: arXiv
Year: 2008
Subjects: subject: Dynamical Systems (math.DS)
subject: FOS: Mathematics

description: Arnold's diffusion in quasi integrable hamiltonian systems occurs in exponentially large time. We study an initially hyperbolic system which admits diffusion in polynomial time.
The amplitude of solar oscillations using stellar techniques
Creators: name: Kjeldsen, Hans
name: Bedding, Timothy R.
name: Arentoft, Torben
name: Butler, R. Paul
name: Dall, Thomas H.
name: Karoff, Christoffer
name: Kiss, Laszlo L.
name: Tinney, C. G.
name: Chaplin, William J.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: The amplitudes of solar-like oscillations depend on the excitation and damping, both of which are controlled by convection. Comparing observations with theory should therefore improve our understanding of the underlying physics. However, theoretical models invariably compute oscillation amplitudes relative to the Sun, and it is therefore vital to have a good calibration of the solar amplitude using stellar techniques. We have used daytime spectra of the Sun, obtained with HARPS and UCLES, to measure the solar oscillations and made a detailed comparison with observations using the BiSON helioseismology instrument. We find that the mean solar amplitude measured using stellar techniques, averaged over one full solar cycle, is 18.7 +/- 0.7 cm/s for the strongest radial modes (l=0) and 25.2 +/- 0.9 cm/s for l=1. In addition, we use simulations to establish an equation that estimates the uncertainty of amplitude measurements that are made of other stars, given that the mode lifetime is known. Finally, we also give amplitudes of solar-like oscillations for three stars that we measured from a series of short observations with HARPS (gamma Ser, beta Aql and alpha For), together with revised amplitudes for five other stars for which we have previously published results (alpha Cen A, alpha Cen B, beta Hyi, nu Ind and delta Pav).
description: 8 pages, accepted by ApJ. Minor wording changes and added a reference
Janulum
Creators: name: Kelly, Michelle
name: Erpenbeck, Dirk
name: Morrow, Christine
name: Soest, Rob Van
Publisher: name: Zenodo
Year: 2015
Subjects: Biodiversity
Taxonomy
Animalia
Porifera
Demospongiae
Poecilosclerida
Raspailiidae
Janulum

description: Genus Janulum de Laubenfels
 Janulum de Laubenfels, 1936: 79.
 Type species. Janulum spinispiculum (Carter, 1876) (type by original designation).
 Diagnosis. Encrusting sponges with a smooth or lobed to columnar, distinctly punctate surface, with a firm to crisp, fragile texture in life. Colour in life ranges from pale yellow to cream to translucent pale blue. Choanosomal architecture consists of a single category of peculiar spined strongyles arranged in a delicate isodictyal reticulation of single spicules. Ectosome a tangential isodictyal reticulation. Spined strongyles are straight or bent abruptly at each end; typically ends bend to the same side of the spicule but may also bend to opposite sides. Strongyles possess sharp concave spines concentrated in the middle of the strongyle, ends are rounded, smooth, slightly expanded. Spines project perpendicular to the shaft and are aligned in what appear to be short linear spiralling arrays. A few spicules, often thin and immature, may be entirely smooth (modified and expanded from Vacelet (1969) and Boury-Esnault et al. (1994)).
description: Published as part of Kelly, Michelle, Erpenbeck, Dirk, Morrow, Christine & Soest, Rob Van, 2015, First record of a living species of the genus Janulum (Class Demospongiae) in the Southern Hemisphere, pp. 255-266 in Zootaxa 3980 (2) on page 258, DOI: 10.11646/zootaxa.3980.2.6, http://zenodo.org/record/236017
The information loss of a stochastic map
Creators: name: Fullwood, James
name: Parzygnat, Arthur J.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Information Theory (cs.IT)
subject: Category Theory (math.CT)
subject: Probability (math.PR)
subject: FOS: Computer and information sciences
subject: FOS: Mathematics
subject: 94A17 (Primary), 18A05, 62F15 (Secondary)

description: We provide a stochastic extension of the Baez-Fritz-Leinster characterization of the Shannon information loss associated with a measure-preserving function. This recovers the conditional entropy and a closely related information-theoretic measure that we call conditional information loss. Although not functorial, these information measures are semi-functorial, a concept we introduce that is definable in any Markov category. We also introduce the notion of an entropic Bayes' rule for information measures, and we provide a characterization of conditional entropy in terms of this rule.
description: 31 pages; Typos fixed in Defn 2.12 and the proofs of Prop 4.2 iii) and Prop 6.8 (numbering scheme differs from published version)
Additional file 5 of Production of succinate by engineered strains of Synechocystis PCC 6803 overexpressing phosphoenolpyruvate carboxylase and a glyoxylate shunt
Creators: name: Durall, Claudia
name: Kukil, Kateryna
name: Hawkes, Jeffrey A.
name: Albergati, Alessia
name: Lindblad, Peter
name: Lindberg, Pia
Publisher: name: figshare
Year: 2021
Subjects: subject: Biophysics
subject: Biochemistry
subject: Space Science
subject: Medicine
subject: Microbiology
subject: FOS: Biological sciences
subject: Ecology
subject: 69999 Biological Sciences not elsewhere classified
subject: Marine Biology

description: Additional file 5. Statistical analysis showing the p values obtained when the Student's two-tailed t-test was performed comparing succinate titers in the media (Additional file 1) of the same strain between different light conditions but after same treatments.
Postglacial history of East European boreal forests in the mid-Kama region, pre-Urals, Russia
Creators: name: Shumilovskikh, Lyudmila S.
name: Schmidt, Monika
name: Pereskokov, Mikhail
name: Sannikov, Pavel
Publisher: name: FID GEO
Year: 2020

description: The Ural Mountains are an important climatic and biogeographical barrier between European and Siberian forests. In order to shed light on the postglacial formation and evolution of the boreal forests in the European pre-Urals, we obtained a peat sediment core, Chernaya, from the Paltinskoe bog located between the southern taiga and hemiboreal forest zone in the mid-Kama region. We carried out pollen analysis, non-pollen palynomorph analysis, loss-on-ignition tests and radiocarbon dating. Radiocarbon dated records provide centennial to decennial resolution of the vegetation and environmental history of the European pre-Urals for the last 8.8 ka. The postglacial formation of the pre-Uralian hemiboreal forests reveals four important phases: (i) the dominance of Siberian taiga and forest-steppe in the Early Holocene and beginning of the Middle Holocene (8.8–6.9 ka), indicating a dry climate; (ii) the spread of spruce and European broadleaved trees in the Middle Holocene (6.9–4 ka) under wetter climate conditions; (iii) the maximum extent of broadleaved trees coinciding with the arrival and spread of Siberian fir in the Late Holocene (4–2.3 ka); and (iv) the decline of broadleaved trees since the Early Iron Age (2.3 ka – present) possibly due to general climate cooling and logging. While temperate broadleaved trees possibly spread from local refugia in the Urals, fir arrived from Siberia and spread further west. The carbon accumulation rate of Paltinskoe bog (18.9±10.16 g C m−2 a−1) is close to the average value of carbon accumulation of northern peatlands. Local development of peat is characterized by non-gradual growth with a phase of intensive carbon accumulation between 3.5 and 2.3 ka. The vegetation was strongly influenced by fire in the Early Holocene and by humans since the Early Iron Age practicing deforestation, agriculture and pasture. Phases of increased anthropogenic activity correlate well with the local archaeological data.
Quantum instability and edge entanglement in a quasi-long-range order
Creators: name: Son, Wonmin
name: Amico, Luigi
name: Plastina, Francesco
name: Vedral, Vlatko
Publisher: name: arXiv
Year: 2008
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We investigate the build-up of quasi-long-range order in the XX chain with transverse magnetic field at finite size. As the field is varied, the ground state of the system displays multiple level crossings producing a sequence of entanglement jumps. Using the partial fidelity and susceptibility, we study the transition to the thermodynamic limit and argue that the topological order can be described in terms of kink-antikink pairs and marked by edge spin entanglement.
description: 5pages and 6 figures
Photovoltaic array simulators
Creators: name: Liu, Guang
Publisher: name: University of British Columbia
Year: 2010

description: Two basic types of photovoltaic (PV) array simulator have been designed and tested. The first involves the use of a pilot panel and variable light source. It is implemented with analogue circuits. A stability analysis based on Popov's method is presented for this simulator with resistance-inductance (R-L) loads. In the second, characteristic array curves are stored in the memory of a microprocessor-based simulator. The design of both simulators is based on the transfer function method. By using the computing facility available, a stability study for the Type I simulator and some dynamic simulations are carried out. Both simulators are capable of driving a special load, namely, an experimental solar pumping system. The experimental results for both types of' simulator are satisfactory in terms of steady state precision and dynamic behaviour when used with this load. Compared with previously-reported PV array simulator designs [6,7,8,9,18], the two simulators described here have the following distinctive features: 1. A new method of sample curve generation for the Type II simulator results in relatively short sampling period and small memory size. 2. The sample curves of the type II simulator are based directly on the real PV array to be simulated. They are more accurate than the sample curves in references [6,7,9]. 3. Different loads (R, R-L and an experimental solar pumping system) have been considered in the design and have been tested in laboratory. 4. A stability analysis and some dynamic simulations are presented for the type I simulator. An analysis of this type has not been reported in previous studies [6,7,8,9,18].
Latent Modes of Nonlinear Flows -- a Koopman Theory Analysis
Creators: name: Cohen, Ido
name: Gilboa, Guy
Publisher: name: arXiv
Year: 2021
Subjects: subject: Dynamical Systems (math.DS)
subject: FOS: Mathematics

description: Extracting the latent underlying structures of complex nonlinear local and nonlocal flows is essential for their analysis and modeling. In this work, we attempt to provide a consistent framework through Koopman theory and its related popular discrete approximation -- dynamic mode decomposition (DMD). We investigate the conditions to perform appropriate linearization, dimensionality reduction, and representation of flows in a highly general setting. The essential elements of this framework are Koopman Eigenfunction (KEF), for which existence conditions are formulated. This is done by viewing the dynamic as a curve in state-space. These conditions lay the foundations for system reconstruction, global controllability, and observability for nonlinear dynamics. We examine the limitations of DMD through the analysis of Koopman theory and propose a new mode decomposition technique based on the typical time profile of the dynamics. An overcomplete dictionary of decay profiles is used to sparsely approximate the flow. This analysis is also valid in the full continuous setting of Koopman theory, which is based on variational calculus. We demonstrate applications of this analysis, such as finding KEFs and their multiplicities, dynamics reconstruction, and global linearization.
description: Visit our websites https://idoc.webgr.technion.ac.il/ and https://guygilboa.net.technion.ac.il/. The MatLab code is available in https://github.com/IdoCohen5743/Examining-the-Limitations-of-DMD-through-Koopman-Theory-Analysis
A Critical Evaluation of Deep Blue Algorithm Derived AVHRR Aerosol Product Over China
Creators: name: Mei, Linlu
name: Zhao, Chuanxu
name: De Leeuw, Gerrit
name: Burrows, John P.
name: Rozanov, Vladimir
name: Che, HuiZheng
name: Vountas, Marco
name: Ladstätter-Weißenmayer, Annette
name: Zhang, Xiaoye
Publisher: name: FID GEO
Year: 2019

description: The Deep Blue (DB) aerosol retrieval algorithm has recently been applied to Advanced Very High Resolution Radiometer (AVHRR) data to produce a first version (V001) of a global aerosol optical thickness (AOT) data set. In this paper, we critically evaluate these AVHRR AOT data over China by comparison with ground-based reference data from China Aerosol Remote Sensing Network for the period 2006–2011. The evaluation considers the impact of the surface (type and reflectance) and the aerosol properties (aerosol loading, aerosol absorption) on the quality of the retrieved AOT. We also compare the AVHRR-retrieved AOT with that from Moderate Resolution Imaging Spectroradiometer over major aerosol source regions in China. We further consider seasonal variations and find, in general, a good agreement between AVHRR AOT and the reference data sets. The AVHRR retrieval algorithm performs well over dark vegetated surfaces, but over bright surfaces (e.g., desert regions) the results are less good. The AVHRR algorithm underestimates the AOT, with 32.1% of the values lower than the estimated error envelope of ±0.05 ± 0.25τ. In particular over the desert, the AVHRR-retrieved AOT is frequently underestimated and for AOT ≤ 0.6 the values are on average 0.05 too low due to the pixel filtering, and dust storms are missed. The comparison of the AVHRR AOT with MODIS collection 6 and CARSNET data indicates that improvements are needed for, for example, AVHRR calibration and cloud/aerosol flagging. The analysis presented in this paper contributes to a better understanding of the AVHRR AOT product over China.
Solving Constraint Satisfaction Problems through Belief Propagation-guided decimation
Creators: name: Montanari, Andrea
name: Ricci-Tersenghi, Federico
name: Semerjian, Guilhem
Publisher: name: arXiv
Year: 2007
Subjects: subject: Artificial Intelligence (cs.AI)
subject: Disordered Systems and Neural Networks (cond-mat.dis-nn)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Computational Complexity (cs.CC)
subject: FOS: Computer and information sciences
subject: FOS: Physical sciences

description: Message passing algorithms have proved surprisingly successful in solving hard constraint satisfaction problems on sparse random graphs. In such applications, variables are fixed sequentially to satisfy the constraints. Message passing is run after each step. Its outcome provides an heuristic to make choices at next step. This approach has been referred to as `decimation,' with reference to analogous procedures in statistical physics. The behavior of decimation procedures is poorly understood. Here we consider a simple randomized decimation algorithm based on belief propagation (BP), and analyze its behavior on random k-satisfiability formulae. In particular, we propose a tree model for its analysis and we conjecture that it provides asymptotically exact predictions in the limit of large instances. This conjecture is confirmed by numerical simulations.
description: 10 pages, 4 figures. A longer version can be found as arXiv:0904.3395 [cond-mat.dis-nn]
Melting phase diagram of bubble phases in high Landau levels
Creators: name: Villegas, K. A.
name: Singh, S. K.
name: Deng, H.
name: Chung, Y. J.
name: Pfeiffer, L. N.
name: West, K. W.
name: Baldwin, K. W.
name: Shayegan, M.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: A low-disorder, two-dimensional electron system (2DES) subjected to a large perpendicular magnetic field and cooled to very low temperatures provides a rich platform for studies of many-body quantum phases. The magnetic field quenches the electrons' kinetic energy and quantizes the energy into a set of Landau levels, allowing the Coulomb interaction to dominate. In excited Landau levels, the fine interplay between short- and long-range interactions stabilizes bubble phases, Wigner crystals with more than one electron per unit cell. Here we present the screening properties of bubble phases, probed via a simple capacitance technique where the 2DES is placed between a top and a bottom gate and the electric field penetrating through the 2DES is measured. The bubbles formed at very low temperatures screen the electric field poorly as they are pinned by the residual disorder potential, allowing a large electric field to reach the top gate. As the temperature is increased, the penetrating electric field decreases and, surprisingly, exhibits a pronounced minimum at a temperature that appears to coincide with the melting temperature of the bubble phase. We deduce a quantitative phase diagram for the transition from bubble to liquid phases for Landau level filling factors $4\leqν\leq5$.
Arlequín y Polichinela, Valle Inclán y García Lorca : estudio comparativo, histórico y literario sobre la commedia dell’arte y los títeres
Creators: name: Avila Hesles, Gerardo
Publisher: name: University of British Columbia
Year: 2010

description: The popularity of commercial theatre such as the "melodrama" and the "género chico" presented a barrier to new and experimental theatre at the turn of the twentieth century in Spain. Foremost among the dramatists who attempted to overcome such obstacle were Ramón del Valle Inclán and Federico García Lorca whose early productions were based on commedia dell' arte, puppetry, and generally in popular traditional theatre. The first part of this study (written in Spanish) explores the origins and development of Harlequin in the Italian commedia and traces his presence in the Spanish Renaissance using the work of Cervantes as an example. The historical background of Harlequin is indispensable in understanding Valle Inclán's attitudes towards the commedia. Harlequin is the central figure in his play La Marquesa Rosalinda first performed in 1912. Valle Inclán uses names found in Cervantes's works and through metaphores, sets out to explain the canons of commedia dell' arte that was the heart and pulse of popular theatre in the Renaissance. This thesis examines the height and decline of the commedia in the eighteenth century and includes a study of La Marquesa Rosalinda in terms of its indebitness to the commedia on one hand and Valle Inclán's original development on the other. The second half of this study deals with two works of García Lorca that involve his character Don Cristóbal Polichinela. Don Cristóbal, based on the popular Spanish puppet of the same name, has been inspired by the masked Punchinello of the seventeenth century commedia. A historical and literary appraisal is used to trace the most important characteristics of Punchinello including his transformation from a man into a puppet. Particular emphasis is placed upon the presence of this puppet in Spain, its connection to Harlequin, and the utilization of Punchinello by García Lorca. To conclude this thesis, a comparative study based on the two zanies, Harlequin and Punchinello, enlightens the reasons and motives for the use of puppets and puppets-like characters in the works of Valle Inclán and García Lorca.
Hash Property and Fixed-rate Universal Coding Theorems
Creators: name: Muramatsu, Jun
name: Miyake, Shigeki
Publisher: name: arXiv
Year: 2008
Subjects: subject: Information Theory (cs.IT)
subject: FOS: Computer and information sciences

description: The aim of this paper is to prove the achievability of fixed-rate universal coding problems by using our previously introduced notion of hash property. These problems are the fixed-rate lossless universal source coding problem and the fixed-rate universal channel coding problem. Since an ensemble of sparse matrices satisfies the hash property requirement, it is proved that we can construct universal codes by using sparse matrices.
description: submitted to IEEE Transactions on Information Theory, Mar. 2008. 15 pages
Brownian subordinators and fractional Cauchy problems
Creators: name: Baeumer, Boris
name: Meerschaert, Mark M.
name: Nane, Erkan
Publisher: name: arXiv
Year: 2007
Subjects: subject: Probability (math.PR)
subject: Analysis of PDEs (math.AP)
subject: FOS: Mathematics
subject: 60J65, 60J60, 26A33

description: A Brownian time process is a Markov process subordinated to the absolute value of an independent one-dimensional Brownian motion. Its transition densities solve an initial value problem involving the square of the generator of the original Markov process. An apparently unrelated class of processes, emerging as the scaling limits of continuous time random walks, involve subordination to the inverse or hitting time process of a classical stable subordinator. The resulting densities solve fractional Cauchy problems, an extension that involves fractional derivatives in time. In this paper, we will show a close and unexpected connection between these two classes of processes, and consequently, an equivalence between these two families of partial differential equations.
description: 18 pages, minor spelling corrections
Characterizing Water Flow in Vegetated Lysimeters with Stable Water Isotopes and Modeling
Creators: name: Shajari, Fatemeh
name: Einsiedl, Florian
name: Rein, Arno
Publisher: name: FID GEO
Year: 2019

description: We have used stable water isotopes (δ18O, δ2H) in combination with lumped-parameter modeling for characterizing unsaturated flow in two lysimeters vegetated with maize. The lysimeters contained undisturbed soil cores dominated by sandy gravel (Ly1) and clayey sandy silt (Ly2). Stable water isotopes were analyzed in precipitation and lysimeter outflow water over about 3 years. The mean transit time of water T and dispersion parameter PD, obtained from modeling, were higher for the silt soil in Ly2 than for the gravel soil in Ly1 (T of 362 vs. 129 d, PD of 0.7 vs. 0.12). The consideration of preferential flow (PF) paths could substantially improve the model curve fits, with 13 and 11% contribution of PF for Ly1 and Ly2 as best estimates. Different assumptions were compared to estimate the input function, that is, stable water isotope content in the recharging water. Using the isotopic composition of precipitation as input (no modification) resulted in reasonable model estimations. Best model fits for the entire observation were obtained by weighting the recharging isotopes according to average precipitation within periods of 3 and 6 months, in correspondence to changing vegetation phases and seasonal influences. Input functions that consider actual evapotranspiration could significantly improve modeling at some periods, however, this led to deviations between modeled and observed δ18O at other periods. This may indicate the influence of variable flow, so that dividing the whole observation period into hydraulically characteristic sub-periods for lumped-parameter modeling (which implements steady-state flow) is recommended for possible further improvement.
A proton simulator for testing implementations of proton CT reconstruction algorithms on GPGPU clusters
Creators: name: Witt, Micah
name: Schultze, Blake
name: Schulte, Reinhard
name: Schubert, Keith
name: Gomez, Ernesto
Publisher: name: arXiv
Year: 2021
Subjects: subject: Medical Physics (physics.med-ph)
subject: FOS: Physical sciences

description: Proton computed tomography (pCT) is an image modality that will improve treatment planning for patients receiving proton radiation therapy compared with the current treatment techniques, which are based on X-ray CT. Reconstruction of a pCT image requires solving a large and sparse system of linear equations, which should be accomplished within a few minutes in order to be clinically practical. Analyzing the efficiency of potentially clinical reconstruction implementations requires multiple quality pCT data sets. The purpose of this paper is to describe the simulator that was developed to generate realistic pCT data sets to be used in testing the efficiency of reconstruction algorithms, in particular string-averaging and block-iterative projection algorithms using sparse matrix formats on General Purpose Graphics Processing Units (GPGPU)s.
description: 4 pages, 11 figures, 2012 IEEE Nuclear Science Symposium and Medical Imaging Conference Record (NSS/MIC)
A Radar for the Internet
Creators: name: Latapy, Matthieu
name: Magnien, Clemence
name: Ouedraogo, Frederic
Publisher: name: arXiv
Year: 2008
Subjects: subject: Networking and Internet Architecture (cs.NI)
subject: FOS: Computer and information sciences

description: In contrast with most internet topology measurement research, our concern here is not to obtain a map as complete and precise as possible of the whole internet. Instead, we claim that each machine's view of this topology, which we call ego-centered view, is an object worth of study in itself. We design and implement an ego-centered measurement tool, and perform radar-like measurements consisting of repeated measurements of such views of the internet topology. We conduct long-term (several weeks) and high-speed (one round every few minutes) measurements of this kind from more than one hundred monitors, and we provide the obtained data. We also show that these data may be used to detect events in the dynamics of internet topology.
description: 8 pages
The high temperature mechanical properties and the correlated microstructure/texture evolutions of a TWIP high entropy alloy
Creators: name: Nabizada, A.
name: Zarei-Hanzaki, A.
name: Abedi, H. R.
name: Barati, M. H.
name: Asghari-Rad, P.
name: Kim, H. S.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: The present work deals with the microstructure and texture evolutions of a TWIP high entropy alloy at various temperatures. Toward this end, the tensile tests were conducted at temperatures ranging from 298 to 873 K under the strain rate of 0.001s-1. The experimented material exhibited an extraordinary room temperature work hardening behavior, in respect of both the instantaneous strain hardening exponent and the work hardening rate values. This resulted in an acceptable ultimate tensile strength /ductility balance and was justified considering the high activity of twinning and planar slip. Such work hardening capacity deteriorated at higher temperatures due to increasing the dislocation annihilation rate and the stacking fault energy values that suppressed twin formation and dislocation accumulation. However, the decrease in amplitude and extent of the work hardening region was insignificant compared with other single-phase high entropy alloys. This was attributed to the high capacity of the alloy for dislocation storage at various deformation temperatures. The serrated flow was observed at 773 and 873 K due to the dynamic strain aging (DSA) mechanism. Interestingly, in this case, the DSA mechanism has a beneficial effect on overall ductility, which was attributed to the increase in the strain hardening exponent result in a delay of necking. Texture examination also reveals the formation of a double fiber texture due to the simultaneous contribution of twinning and octahedral slip.
description: 27 pages, 13 Figures and 3 Tables
Tutoriels autour de l'Open Access
Creators: name: Latour, Marie
Publisher: name: Zenodo
Year: 2019
Subjects: Doctorat
Pluridisciplaire
Open Access
Libre accès
Heloïse
OpenDOAR
SHERPA/RoMEO

description: Vous trouverez ci-joints trois tutoriels autour de l'Open Access que j'envoie à mes doctorants dans le cadre de formations à l'Open Access. Ils portent sur les outils suivants :

	Héloïse
	OpenDOAR
	SHERPA/RoMEO
Modeling Fluid Reinjection Into an Enhanced Geothermal System
Creators: name: Parisio, Francesco
name: Yoshioka, Keita
Publisher: name: FID GEO
Year: 2020

description: Abstract The manuscript analyzes the stimulation for an Enhanced Geothermal System development in Acoculco, Mexico. Using an analytical penny-shaped hydraulic fracture model covering different propagation regimes, we computed the final fracture length and width by varying fluid properties with temperature. Our analysis indicates that for the given scenario, the fluid viscosity plays a minor role and instead flow rate and time of the stimulation are the controlling variables. We computed the fracture reopening as a consequence of water reinjection in the second stage of the stimulation through numerical computations based on the enriched discontinuity method. The computation shows that a single isolated fracture will not provide sufficient permeability, as the continuous injection will quickly fill and pressurize the crack. We demonstrate that the fracture needs to be connected to a permeable network to avoid excessive pressurization and achieve a commercially exploitable reservoir for Enhanced Geothermal System.
High Performance Implementation of Boris Particle Pusher on DPC++. A First Look at oneAPI
Creators: name: Volokitin, Valentin
name: Bashinov, Alexey
name: Efimenko, Evgeny
name: Gonoskov, Arkady
name: Meyerov, Iosif
Publisher: name: arXiv
Year: 2021
Subjects: subject: Computational Physics (physics.comp-ph)
subject: Distributed, Parallel, and Cluster Computing (cs.DC)
subject: Performance (cs.PF)
subject: FOS: Physical sciences
subject: FOS: Computer and information sciences

description: New hardware architectures open up immense opportunities for supercomputer simulations. However, programming techniques for different architectures vary significantly, which leads to the necessity of developing and supporting multiple code versions, each being optimized for specific hardware features. The oneAPI framework, recently introduced by Intel, contains a set of programming tools for the development of portable codes that can be compiled and fine-tuned for CPUs, GPUs, FPGAs, and accelerators. In this paper, we report on the experience of porting the implementation of Boris particle pusher to oneAPI. Boris particle pusher is one of the most demanding computational stages of the Particle-in-Cell method, which, in particular, is used for supercomputer simulations of laser-plasma interactions. We show how to adapt the C++ implementation of the particle push algorithm from the Hi-Chi project to the DPC++ programming language and report the performance of the code on high-end Intel CPUs (Xeon Platinum 8260L) and Intel GPUs (P630 and Iris Xe Max). It turned out that our C++ code can be easily ported to DPC++. We found that on CPUs the resulting DPC++ code is only ~10% on average inferior to the optimized C++ code. Moreover, the code is compiled and run on new Intel GPUs without any specific optimizations and shows the expected performance, taking into account the parameters of the hardware.