365 research outputs found
Quantum fluctuations of the Chern-Simons theory and dynamical dimensional reduction
We consider a large-N Chern-Simons theory for the attractive bosonic matter
(Jackiw-Pi model) in the Hamiltonian collective-field approach based on the 1/N
expansion. We show that the dynamics of low-lying density excitations around
the ground-state vortex configuration is equivalent to that of the Sutherland
model. The relationship between the Chern-Simons coupling constant lambda and
the Calogero-Sutherland statistical parameter lambda_s signalizes some sort of
statistical transmutation accompanying the dimensional reduction of the initial
problem.Comment: 10 pages, 2 figure
Integrated records of tectonic and climate interactions in the Northern Alpine Foreland Basin sedimentary architecture
Peripheral foreland basins form due to flexural subsidence of the downgoing plate driven by topographic- and slab loading. Their architecture records lithospheric- and crustal-scale processes, and the climate history of the adjacent growing orogen. Previous geological and geophysical observational studies revealed that many foreland basins show along-strike heterogeneous sedimentary architecture, implying that mechanisms controlling basin evolution varied laterally. In the Northern Alpine Foreland Basin (NAFB, also known as Molasse Basin) the along-strike heterogeneity in basin architecture is represented by eastward shallowing of depositional environments during Oligocene-Miocene times. This coincided with the suggested two slab break-off and/or tearing events occurring below the Alps. In this project, we test the hypothesis of whether slab break-off and tearing can control along-strike variable foreland basin architecture. We do this by combining tectonostratigraphic analysis of the NAFB fill and numerical models. Tectonostratigraphic analysis includes interpretation of the 2D/3D seismic data located in the transitional zone of the NAFB (German Molasse) connecting the western and eastern parts of the basin. To investigate the effect of the slab-break off and tearing on the foreland basin evolution we combine 3D thermomechanical- and stratigraphic forward models.
The results of the tectonostratigraphic analysis reveal a northward younging trend of syn-flexural normal fault nucleation which agrees with forebulge migration driven by the advance of the Alpine thrust front during the Oligocene-Miocene. Furthermore, the eastward increase in the magnitude of syn-flexural normal fault offsets suggests an increase in the magnitude of flexural bending of the lower plate. This may have been controlled by lateral variations in the architecture of the lower plate and/or spatiotemporal variations in slab breakoff/tearing. The observed along-strike seismic facies integrated with the published data suggests that the north-south trending intrabasinal coastline migrated from west to east at an average rate of ~ 6 cm/yr. Furthermore, 3D thermomechanical models show that slab tearing will initiate either at the location of a subducted continental terrain (if present along the slab) or where collision starts first in the case of oblique convergence. Subsequently, tearing propagates along the strike at velocities ranging from ~35 cm/yr to 120 cm/yr depending on the margin obliquity, slab age and mantle rheology. The surface expression of slab tearing is the orogen parallel migration of uplift, affecting both the orogen and peripheral foreland basin. In the peripheral foreland basins associated with the collision of oblique margins, this uplift leads to a gradual along-strike decrease of accommodations space followed by shallowing of depositional environments. However, during the collision of irregular margins, the size and rheology of irregular terrains exert a key influence on the along-strike distribution of the surface uplift during tearing. Typically, this yields a more stepwise distribution of the accommodation space along the peripheral foreland, i.e. lower above the previously accreted terrain.
Currently, we are focusing on integrating thermomechanical- and forward stratigraphic models to estimate the effect of environmental factors such as sea-level variations, and precipitation rates on the preservation of the slab break-off and tearing signals in the stratigraphic record of peripheral foreland basins
Slab tearing in non-collisional settings: Insights from thermo-mechanical modelling of oblique subduction
The propagation of slab break-off (slab tearing) is usually attributed to laterally variable plate convergence systems with a spatial transition between simultaneous oceanic subduction and continental collision. To study the process of slab tearing in a non-collisional geodynamic context, here we use a 3D thermo-mechanical numerical approach to model the oblique subduction of a homogeneous oceanic plate. We investigate the effects of the following parameters: (1) subduction obliquity angle, (2) age of oceanic slab, and (3) partitioning of boundary velocities (i.e., the ratio between the subduction component and the advance of the overriding plate in the total convergence). In our simulations, the retreat of the subduction zone leads to a thinning of the fore-arc and back-arc lithosphere, which are decoupled from the subducting slab by the rise of the hot asthenosphere from the underlying mantle wedge. As a consequence of the initial obliquity of the active plate margin, slab roll-back velocities are subject to progressive along-trench variations. Consistent with the gradual rotation of the trench, the front of the decoupling between the overriding and downgoing plates (together with predicted magmatic activity and topographic uplift) migrates in a horizontal direction. In the experiments with low angles of subduction obliquity ( 50 Ma), and in the absence of the subduction component in the overall shortening, slab detachment either develops simultaneously along the entire length of the subduction zone or does not occur at all. In contrast, with higher subduction obliquity (ā„ 15Ā°), younger slabs (ā¤ 50 Ma) and in the presence of a boundary push on the oceanic side, the initial slab break-off is followed by the gradual growth of the ātearā window in the direction opposite to the migration path of the previously established plates decoupling. The sharp contrast in trench retreat rates between subduction zone segments affected and unaffected by slab detachment results in the arcuate shape of the trench. Furthermore, the direction of slab tearing may change from horizontal to vertical, eventually leading to the formation of a transform fault on the subducting plate. Our results show striking similarities with several features ā such as trench curvature, subduction zone segmentation, magmatic production, lithospheric stress/deformation fields, and associated topographic changes ā observed in many subduction zones (e.g., Marianas, New Hebrides, Mexico, Calabrian)
Totally classical Calogero model
We show that the standard Calogero Lax matrix can be interpreted as a
function on the fuzzy sphere and the Avan-Talon r-matrix as a function on the
direct product of two fuzzy spheres. We calculate the limiting Lax function and
r-function when the fuzzy sphere tends to the ordinary sphere and we show that
they define an integrable model interpreted as a large N Calogero model by
Bordemann, Hoppe and Theisen.Comment: 13 pages, revised version taking into account relevant results by
Bordemann, Hoppe and Theise
First record of the bacterial endosymbiont Wolbachia for phytophagous hoverflies from genus Merodon (Diptera : Syrphidae)
Wolbachia is a widespread bacterial endosymbiont among arthropod species. It influences the reproduction of the host species and also mitochondrial DNA diversity. Until now there were only a few studies that detected Wolbachia infections in hoverflies (Diptera: Syrphidae), and this is the first broader study with the aim of examining the incidence of Wolbachia in the hoverfly genus Merodon. The obtained results indicate an infection rate of 96% and the presence of both Wolbachia supergroup A and B, which are characteristic for most of the infected arthropod species. Additionally, the presence of multiple Wolbachia strains in the Merodon aureus group species was detected and the mitochondrial DNA COI-based relationships of the group are discussed in the light of infection. Finally, we discuss plant-mediated horizontal transmission of Wolbachia strains among the studied hoverfly species.Peer reviewe
Signals of slab breakoff- and tearing in the stratigraphic architecture of a foreland basin
A significant change in the architecture of peripheral pro-foreland basins observed in all natural examples is the flysch to molasse transition (i.e., shift from underfilled- to overfilled conditions). Forcing mechanisms for pro-foreland basin architecture include changes in sediment supply from the adjacent growing orogen and flexural subsidence in the basin. As these forcing mechanisms themselves are driven by orogenic processes in the adjacent mountain range, the flysch to molasse transition can be regarded as the sedimentary fingerprint of hinterland tectonics.
Slab breakoff of the foreland plate leading to isostatic rebound of both the pro-foreland basin and adjacent orogen (leading to increased sediment supply) has been suggested to be a driver of the flysch to molasse transition. However, this cause-and-effect relationship between slab breakoff and the flysch to molasse transition is based on qualitative assessments. This raises the question whether other external forcings may have masked the contribution of slab breakoff to the flysch to molasse transition.
In this study we investigate the stratigraphic signal of slab breakoff in a pro-foreland basin. To quantitatively assess the relationship between slab breakoff and the flysch to molasse transition, we coupled 2D geodynamic models (GMs) of slab breakoff using LaMEM with 2D forward stratigraphic modelling (FSM) using the GPM software (SLB). To better understand the influence of slab breakoff on pro-foreland basin architecture, we tested slab breakoff scenarios in our GMs for varying 1) slab bending angles and 2) slab necking durations (depending on slab rheology). To test whether the stratigraphic signal of slab breakoff may be masked by other external forcings, we introduced eustatic sea level changes (50 m amplitude with a 1 My period). From our FSMs we generated sediment thickness maps used to reconstruct sediment supply rates, grain size distribution- and facies maps and synthetic seismic data to compare with observed seismic data.
Our preliminary results indicate that vertical uplift due to isostatic rebound in the pro-foreland basin (1.5 ā 7 cm/yr, where fast necking of steep slabs yields higher values) decreases the accommodation space, leading to a stratigraphically upward shallowing. Furthermore, isostatic rebound of the adjacent mountain range (2-5 cm/yr, same relationship with slab dynamics as pro-foreland basin) results in up to 2.5x increased rates of sediment supply with very little lag time, adding to the stratigraphically upward shallowing. The eustatic sea level changes do not mask the stratigraphic signal of slab breakoff. Lastly, the facies of the flysch to molasse transition in our synthetic seismics looks similar to that observed on seismics of the Austrian Molasse which occurred coeval with slab breakoff under the Eastern Alps
The classical hydrodynamics of the Calogero-Sutherland model
We explore the classical version of the mapping, due to Abanov and Wiegmann,
of Calogero-Sutherland hydrodynamics onto the Benjamin-Ono equation ``on the
double.'' We illustrate the mapping by constructing the soliton solutions to
the hydrodynamic equations, and show how certain subtleties arise from the need
to include corrections to the naive replacement of singular sums by
principal-part integrals.Comment: 21 pages, RevTeX, one figure. Typos fixed; reference added; more
details in appendi
Supplementary data for article: Å egan, S. B.; AndriÄ, F.; RadoiÄiÄ, A.; Opsenica, D. M.; Å olaja, B. A.; ZlatoviÄ, M.; MilojkoviÄ-Opsenica, D. Correlation between Structure, Retention and Activity of Cholic Acid Derived Cis-Trans Isomeric Bis-Steroidal Tetraoxanes. Journal of Separation Science 2011, 34 (19), 2659ā2667. https://doi.org/10.1002/jssc.201100185
Supporting information for: [https://doi.org/10.1002/jssc.201100185]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/1212
Solitons and giants in matrix models
We present a method for solving BPS equations obtained in the
collective-field approach to matrix models. The method enables us to find BPS
solutions and quantum excitations around these solutions in the one-matrix
model, and in general for the Calogero model. These semiclassical solutions
correspond to giant gravitons described by matrix models obtained in the
framework of AdS/CFT correspondence. The two-field model, associated with two
types of giant gravitons, is investigated. In this duality-based matrix model
we find the finite form of the -soliton solution. The singular limit of this
solution is examined and a realization of open-closed string duality is
proposed.Comment: 17 pages, JHEP cls; v2: final version to appear in JHEP, 2 references
added, physical motivation and interpretation clarifie
Duality and quasiparticles in the Calogero-Sutherland model: Some exact results
The quantum-mechanical many-body system with the potential proportional to
the pairwise inverse-square distance possesses a strong-weak coupling duality.
Based on this duality, particle and/or quasiparticle states are described as
SU(1,1) coherent states. The constructed quasiparticle states are of
hierarchical nature.Comment: RevTeX, 10 page
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