bluuebunny/crossref_metadata_2025 huggingface dataset:
Constraints from 40Ar/39Ar geochronology on the tectonothermal history of the Kapuskasing uplift in the Canadian Superior Province
Authors: Hanes J. A. , Archibald D. A. , Queen M. , Farrar E.
Published: April 2010

The Kapuskasing uplift (KU) in the Superior Province of the Canadian Shield has been interpreted as an oblique cross section through the Archean mid-crust. However, the time of juxtaposition of the granulites of the KU against the lower grade rocks of the Abitibi greenstone belt (AGB) along the Ivanhoe Lake fault zone is problematic. To constrain the postmetamorphic tectonothermal history of the KU, we have conducted 57 40Ar/39Ar step-heating analyses on mineral and rock samples collected in a transect across the southern KU and adjacent AGB. The age spectra record a complex thermal history. Amphiboles from the AGB in the footwall of the Ivanhoe Lake fault zone have ca. 2.66 Ga dates, similar to closure ages for amphiboles from farther east in the AGB. Amphibole dates of 2.46–2.52 Ga from the deepest structural levels of the KU place an upper limit on the time of major uplift of the granulites and their juxtaposition with the AGB. Biotite and muscovite dates from the transect cluster into three age groups. The presence in the deepest structural levels of the KU of biotite with 2.40–2.45 Ga dates indicates that significant uplift (15–20 km or more) of the granulites had occurred by this time. Micas with dates in the 2.25–2.30 Ga range are close to fault zones; these dates may indicate a ca. 2.30 Ga episode of fault reactivation. Feldspar, fault-related whole rocks, and some micas record events post 2.1 Ga. These correspond to the emplacement of mafic and lamprophyric dykes and fault reactivation.
Onaping fault system: age constraints on deformation of the Kapuskasing structural zone and units underlying the Sudbury Structure
Authors: Buchan Kenneth L. , Ernst Richard E.
Published: April 2010

The deformation of the Matachewan dyke swarm of the Superior Province, which includes a 60 km right-lateral offset and moderate uplift localized along the Kapuskasing structural zone, represents an important time marker in the evolution of the zone. However, the age of this deformation is poorly constrained. Here, it is shown that the prominent Mattagami River – Upper Wanapitei River fault of the Onaping fault system, which offsets 2167 Ma Biscotasing dykes south of the Kapuskasing structural zone, can be aligned with a fault of similar offset north of the zone after the Matachewan swarm is restored to its predeformational configuration. Thus, the deformation of the Matachewan swarm in the vicinity of the Kapuskasing structural zone must postdate the 2167 Ma emplacement and the subsequent faulting of the Biscotasing dykes. Southward extensions of faults of the Onaping fault system appear to offset aeromagnetic anomalies associated with highly magnetic units in the basement beneath the Sudbury Structure and Huronian sediments of the Southern Province, but do not substantially offset the Sudbury Structure itself. This suggests that the 1850 Ma Sudbury Structure was emplaced after most of the displacement on Onaping faults, while the unit underlying it, variously interpreted as the Archean Levack Gneiss Complex or a hidden ultramafic body of unknown age, predates Onaping faulting.
Quantitative estimates of emplacement level of postmetamorphic mafic dykes and subsequent erosion magnitude in the southern Kapuskasing uplift
Authors: Percival J. A. , Palmer H. C. , Barnett R. L.
Published: April 2010

The Early Proterozoic Matachewan (2.454 Ga) and Kapuskasing (2.04 Ga) dyke swarms of the central Superior Province have similar petrographic features, including zoned igneous plagioclase and clinopyroxene and interstitial amphibole and quartz. Dyke crystallization conditions can be estimated using equilibria involving amphibole by assuming that igneous mineral rims reached equilibrium with the interstitial phases.TWQ software using 33 amphibole-bearing equilibria yields temperatures ranging from 552 to 811 °C, with an average of 680 °C. The average of two calibrated pressure-sensitive equilibria (2 diopside + 2 quartz + tschermakite = tremolite + 2 anorthite and diopside + 5 quartz + pargasite = tremolite + anorthite + albite) ranges from 0.32 to 0.70 GPa for Matachewan dykes and from 0.30 to 0.57 GPa for Kapuskasing dykes. Because dyke pressures are lower than metamorphic pressures in the amphibolite- and granulite-facies Archean country rocks, the values represent feasible emplacement pressures.The regional patterns of erosion level derived from dyke pressures have similarities to those based on other lines of evidence. Across the Kapuskasing uplift, easterly deepening structural levels are indicated by increasing metamorphic pressure (~0.4–1.1 GPa). The 0.30–0.70 GPa dyke pressures reflect similar geometry and constrain the magnitude and timing of uplift. Modest amounts of uplift (0–8 km) prior to emplacement of Matachewan dykes may have been related to faulting in the Kapuskasing structural zone. A similar magnitude (4–7 km) may have occurred in the interval between dyking events, but the main uplift (10–17 km) of high-grade rocks of the Kapuskasing structural zone took place after emplacement of Kapuskasing dykes.
Geochemistry of late (~ 1.1 Ga) fluid inclusions in rocks of the Kapuskasing Archean crustal section
Authors: Channer D. M. DeR. , Spooner E. T. C.
Published: April 2010

Three outcrops, well constrained by geochronological and structural studies, and representing a traverse running from tonalite-dominated outcrops in the eastern Wawa gneiss terrane to high-grade granulites of the Kapuskasing structural zone, were mapped and sampled in detail in order to study the trapped fluids. All fluid inclusions in quartz are secondary and consist mostly of CO2-dominated (type II) and saline aqueous (type IIIa) fluids usually occurring on separate healed fractures but also coexisting on some fractures. Healed fractures in quartz contain fluid inclusions but are associated with carbonate–sericite alteration where they pass into adjacent mineral grains. Homogeneous H2O–CO2–salt fluid inclusions (type Ia) in carbonate-rich veins of probable Keweenawan (~ 1.1 Ga) age were trapped at 400–550 °C and ambient pressures of 1.5–2 kbar (1 kbar = 100 MPa). As these fluids cooled on penetration into cool (~ 200 °C) country rocks along fractures they underwent open-system H2O-CO2 phase separation from ~ 350 °C down to ~ 190 °C, producing a range of fluid compositions, including physically segregated CO2-rich (type II) and H2O–salt–rich (type IIIa). Combined gas and ion chromatographic bulk fluid inclusion analyses show that fluid types II and IIIa are not related to shield brines. Br−/Cl− ratios of samples containing phase-separated fluids are similar to the Br−/Cl− ratio of fluids in the carbonate-rich vein. The results of this study show that Keweenawan alkalic magmatism caused widespread carbonate alteration throughout the Kapuskasing structural zone and Wawa gneiss domain. The CO2 component of the fluids is probably magmatic in origin, whereas the aqueous part could also be magmatic or, alternatively, formation waters activated by Keweenawan magmatism.
Lithospheric structure in the southern Canadian Cordillera from a network of seismic refraction lines
Authors: Clowes Ron M. , Zelt Colin A. , Amor John R. , Ellis Robert M.
Published: April 2010

Lithospheric velocity structure and its relationship to regional tectonics and development of the southern Canadian Cordillera are derived from a synthesis of interpretations from nine in-line seismic refraction–wide-angle reflection profiles and broadside data recorded during the Lithoprobe Southern Cordillera Refraction Experiment (SCoRE) and other refraction experiments across southern British Columbia, and one profile in northwestern Washington. Consistency of the SCoRE two-dimensional models at their intersection positions is achieved through application of a simultaneous inversion of all relevant traveltime data. The cross-sectional and map presentations demonstrate the strong degree of three-dimensional heterogeneity within the crust and upper mantle. A first-order characteristic is the continuous increase in crustal velocities westward from the Foreland belt to the Insular belt. The variations do not correlate with the morphogeological belts; they do correspond with large-scale geological and (or) tectonic features and seismic reflection results. Crustal thickness varies from 30 to 48 km; a lack of comparable variation in Bouguer gravity anomalies requires significant density changes in the crust. Variations in the seismic parameters do not correlate well with variations in crustal resistivity or heat flow, suggesting that generalizations relating low resistivities, high temperatures, and low seismic velocities must be treated with caution. Seismic heterogeneities are due primarily to lithological and (or) structural variations and are superimposed on the generally low velocities attributed to the thermal regime. An upper mantle reflector beneath the mainland Cordillera is inferred to be the top of a shallow asthenosphere. Westward flow in the warm asthenosphere interacts with the cold lithosphere of the subducting Juan de Fuca plate below the central Coast belt, forming a "sink" that could provide a driving mechanism for the flow.
The reflection Moho beneath the southern Canadian Cordillera
Authors: Cook Frederick A.
Published: April 2010

The transition from the crust to the mantle beneath the Canadian portion of the North American Cordillera varies in depth, geometry, and tectonic age across the orogen. These variations are rarely spatially related to the positions of morphologic or tectonic belts based on surface geology, nor to nearly 25 km of structural relief identified in outcrop and on seismic reflection data. The Moho in this region is thus interpreted to be a long-lived feature, perhaps as old as Proterozoic in the eastern part of the Cordillera, that probably has been active as a structural boundary during periods of crustal contraction and subsequent crustal stretching. Recognition of the Moho and lower crust as a zone of localized tectonic activity provides a partial explanation for the problem of where regional detachments that underlie the foreland thrust and fold belt go as they project westward to deep structural levels beneath the interior of the orogen: they likely project to the base of the crust, where they flatten and cause imbrication of crustal rocks.
Electromagnetic images of crustal structures in southern and central Canadian Cordillera
Authors: Jones Alan Q. , Gough D. Ian
Published: April 2010

Data from more than 400 magnetotelluric soundings, made since the early 1980's in the Canadian Cordillera over a 300 000 km2area between 49 and 53.5°N, are used to image qualitatively regional three-dimensional crustal variation in electrical conductivity by means of phase maps, phase–frequency sections, and maps of resistivity at depth. Two hundred of the soundings were acquired as part of Lithoprobe Southern Canadian Cordillera Transect activities, and their locations were coordinated with the seismic reflection and refraction experiments. The lower crust has a generally pervasive, low resistivity (1–100 Ω·m) throughout the Cordillera west of the Foreland Belt. Within this "Canadian Cordilleran Regional" conductor, the magnetotelluric data reveal both two-dimensional structures, with highest conductivities along the Coast Belt and Omineca Belt, and three-dimensional variation along geological strike. This conductor, mapped over a volume in excess of 106 km3, is most probably caused by fluids–saline waters and silicate melts–in fractures and along interconnected grain boundaries. The observed lateral variations in conductivity may result from variations in fracture density, temperature, and the sources of hot fluid, such as the subducting Juan de Fuca plate under the Coast Belt, and mantle upflow under the Omineca Belt. In addition, we report a major east–west-trending geophysical discontinuity in the upper and middle crust of the Omineca Belt at a latitude of 50°N, with highly resistive rocks (>1000 Ω·m) to the south and more conductive rocks to the north (30–300 Ω·m). Seismic refraction models, residual gravity, and filtered magnetic maps correlate changes in compressional-wave velocity, density, and magnetization along this cross-strike discontinuity.
Tectonic significance of gravity and magnetic variations along the Lithoprobe Southern Canadian Cordillera Transect
Authors: Cook Frederick A. , Varsek John L. , Thurston Jeffrey B.
Published: April 2010

Correlation of potential field data to regional geological features within the Lithoprobe southern Canadian Cordillera transect corridor allows characterization of anomaly patterns according to their likely sources. Long-wavelength Bouguer gravity anomalies are attributed to isostatic effects of topography, which in most areas is compensated. Two notable exceptions occur: in the Foreland belt a large positive isostatic anomaly is likely due to mechanical support of topography formed as Cordilleran thrust sheets were emplaced over the thick craton, and on the west coast, isostatic anomalies are related to active subduction. Long-wavelength magnetic anomalies in the Foreland belt are associated with cratonal basement beneath the thrust sheets, and these can be followed westward to near the Omineca belt. A prominent positive magnetic anomaly along the western Coast belt is probably associated with mafic rocks generated during subduction. Elsewhere, relatively short wavelength gravity and magnetic anomalies correlate well with either plutons (both gravity and magnetic), volcanics (primarily magnetics), or faults (magnetics) within the region of accreted terranes.
Magmatic evolution of the southern Coast Belt: constraints from Nd–Sr isotopic systematics and geochronology of the southern Coast Plutonic Complex
Authors: Friedman R. M. , Mahoney J. B. , Cui Y.
Published: April 2010

Igneous rocks of the southern Coast Belt (SCB) and adjacent Insular Belt developed within a Jurassic–Quaternary magmatic arc built across accreted juvenile-arc and oceanic terranes. SCB plutons are mostly of intermediate composition, with I-type characteristics and major element, trace element, and rare earth element geochemistry consistent with genesis in a subduction-related magmatic arc. Ubiquitous xenoliths and migmatitic zones at pluton–county rock contacts indicate that assimilation of crustal rock was an important magmatic process. U–Pb zircon crystallization ages for SCB and Insular Belt igneous rocks indicate an overall eastward migration of the magmatic axis from Middle Jurassic through Late Cretaceous time. Although absent in most rocks, traces of old inherited zircon are present in several Middle Jurassic–Upper Cretaceous plutons in the southeastern Coast Belt. The primitive character and restricted range of Nd–Sr isotopic data for Middle Jurassic to Quaternary igneous rocks of the SCB (εNd = +2.4 to +8.0; Sri = 0.7030 − 0.7042) indicate they were generated in an isotopically juvenile magmatic arc. The distribution of isotopic values along the mantle array and the wide range of fSm/Nd values suggest magma was derived from depleted mantle within a mantle wedge, with little or no contribution from old, isotopically evolved continental material. Although field evidence suggests that assimilation of juvenile crust was an important process during magma ascent, isotopic and geochemical data do not permit discrimination between direct mantle derivation of magmas followed by fractionation and crustal assimilation, and wholesale melting of mafic arc-derived lower crust.
The southern Omineca Belt, British Columbia: new perspectives from the Lithoprobe Geoscience Program
Authors: Carr Sharon D.
Published: April 2010

Geological, isotopic, and geochronology studies carried out by university and government researchers, concurrently with the Lithoprobe program, have greatly refined our understanding of the regional geology, crustal structure, and tectonics of the Omineca Belt. Sound correlations have been established between surface geology and seismic reflection data. Cretaceous–Eocene thrust faults that are imaged in the subsurface in the Shuswap complex may be part of a break-forward thrust system that feeds into the Purcell Anticlinorium and the Foreland Belt. The Monashee décollement is the western continuation of the sole thrust beneath the Foreland Belt and provides a means of linking shortening across the entire orogen. The thermal peak of metamorphism in the central and southern Shuswap complex is now known to have occurred in the Late Cretaceous–Paleogene in contrast with earlier held views. North American basement rocks are now known to extend beneath the eastern half of the Canadian Cordillera. Geochronology studies have revealed Early Proterozoic and Late Cretaceous–Eocene metamorphism in basement rocks of the Monashee complex, and suggest that these rocks were located to the east of the metamorphic front throughout the Jurassic and Early Cretaceous. Anatectic peraluminous granites were produced in the Shuswap complex between 135 and 52 Ma in response to pulses of crustal thickening and heating, and in some cases served to localize Eocene extensional shear zones and to transfer extensional displacement from one shear zone to another. A flat Moho and other seismic reflection data are consistent with interpretations of lower crustal flow to balance early Tertiary extension in the upper crust. Crustal-scale extension and the Slocan Lake fault zone provided the source and setting for Ag–Pb–Zn–Au mineralization in the Nelson–Silverton area.
Evolution of a Middle Jurassic volcanic arc: stratigraphic, isotopic, and geochemical characteristics of the Harrison Lake Formation, southwestern British Columbia
Authors: Mahoney J. Brian , Friedman Richard M. , McKinley Sean D.
Published: April 2010

The Harrison Lake Formation is an Early to Middle Jurassic volcanic-arc assemblage unconformably overlying Triassic oceanic basement in the eastern Coast Belt of southwestern British Columbia. The formation is subdivided into four members including, in ascending order, the Celia Cove Member (conglomerate), the Francis Lake Member (fine-grained strata), the Weaver Lake Member (flows and breccias), and the Echo Island Member (pyroclastic and epiclastic strata). New biostratigraphic constraints pinpoint the initiation of volcanism to late early Toarcian. U–Pb geochronology demonstrates the arc was active until at least late Bajocian–early Bathonian time (166.0 ± 0.4 Ma), and that the timing of arc volcanism strongly overlaps emplacement of both hypabyssal intrusions (Hemlock Valley stock) and deep-seated plutons (Mount Jasper pluton) within and adjacent to the arc. Geochemical data indicate the arc is of medium- to high-K calc-alkaline affinity, and is strongly light rare earth element enriched (LaN/YbN = 1.5 – 2.5). Nd and Sr isotopic data from primary volcanic rocks demonstrate the juvenile nature of the magmatic system, but isotopic data from associated fine-grained sedimentary rocks suggest temporally controlled variations in isotopic composition interpreted to represent two-component mixing between juvenile volcanic detritus and a more evolved detrital component. The succession of facies in the Harrison Lake Formation records initial basin subsidence in the Early Jurassic, initiation of explosive volcanism in the late early Toarcian, a change to effusive volcanism in the early Aalenian, and late-stage explosive volcanism in the late Bajocian. The Harrison Lake Formation contains mesoscopic folds and overturned bedding that are absent in the overlying Callovian Mysterious Creek Formation, strongly suggesting the existence of a regional Bathonian deformational event in the southern Coast Belt.
The Lithoprobe corridor across the Vancouver Island continental margin: the structural and tectonic consequences of subduction
Authors: Hyndman R. D.
Published: April 2010

The deep structure and tectonic history of the continental margin of southwestern Canada have been determined by phase I of the Lithoprobe program across south-central Vancouver Island and associated marine studies across the continental shelf and slope. This article reviews results from the marine portion of the corridor but also presents continuous onshore–offshore data and interpretation. The geophysical data include multichannel seismic reflection, seismic refraction, magnetics, gravity, bathymetry, sea-floor acoustic imagery, heat flow, and seismicity. There has been Ocean Drilling Program (ODP) coring and downhole measurements on the continental slope. The margin structure and Cenozoic tectonic history are dominated by the consequences of subduction. Two narrow terranes, the Eocene volcanic Crescent and the Mesozoic mainly sedimentary Pacific Rim, were emplaced along the coast at the time of north Pacific plate reorganization at 43 Ma. They provide the landward-dipping backstop to a large accretionary sedimentary prism formed from the sediments scraped off the incoming oceanic plate. The prism exhibits active folding, thrusting, and tectonic consolidation, and it provides a model for the formation of ancient fold and thrust belts. An extensive gas hydrate layer was detected beneath the continental slope by a seismic BSR (bottom-simulating reflector) and was penetrated by the ODP drilling. The surface heat flow decreases landward from high values over the young oceanic plate to low values just seaward of the volcanic arc as a consequence of the heat sink provided by the underthrusting oceanic plate. The margin seismicity includes continental crust-events and earthquakes in the downgoing oceanic plate. No earthquakes have been detected on the subduction thrust fault but great thrust events are inferred to occur with an average interval of 600 years. The seismic source zone for such events is restricted to a narrow region beneath the continental shelf because of the high temperatures over the young Juan de Fuca plate.
5b,7b-Diaza-3b,9b-diborabenzo[ ghi ]perylenes
Authors: Bosdet Michael J.D. , Piers Warren E. , Sorensen Ted S. , Parvez Masood
Published: April 2010

Treatment of a precursor to the chelating Lewis acid 2,2′-diborabiphenyl with 2,6-bisalkynyl-substituted pyridazines, leads to elimination of 2 equiv. of ClSiMe3; subsequent treatment of the mixture with PtCl2 catalyzes the cyclization of observable intermediates to the title 5b,7b-diaza-3b,9b-diborabenzo[ghi]perylene compounds in low isolated yields. The compounds were characterized by NMR and UV–vis spectroscopies, and in one case, by X-ray crystallography. NICS(1) computations indicate that the inner ring is less aromatic than the outer rings.
Synthesis and structures of isopropyl-β-diketiminato copper(I) complexes
Authors: Oguadinma Paul O. , Schaper Frank
Published: April 2010

The reaction of N,N′-diisopropyl-2-amino-4-iminopent-2-ene (nacnaci-PrH, 1) either with CuOt-Bu or with a mixture of mesityl copper and 10% CuOt-Bu afforded, in the presence of PPh3, CN(C6Me2H3), or MeCN, the Lewis base coordinated complexes nacnaci-PrCuPPh3·0.5 C6H14 (2), nacnaci-PrCuCN(C6Me2H3) (3), and nacnaci-PrCu(NCMe) (4). Compounds 2, 3, and 4 were characterized by single-crystal X-ray diffraction studies. Compound 4 afforded two species in deuterated benzene in a 2:1 ratio, which were assigned to {nacnaci-PrCu}2(μ-NCMe) and nacnaci-PrCuNCMe (4). Upon addition of 5 equiv. of MeCN, the two sets collapsed into that of 4. No copper complexes were formed in the presence of styrene, stilbene, or diphenylacetylene.
A novel approach towards the synthesis of tricyclic systems based on pyridine, pyran, thiopyran, azepine, oxepin, thiepin, and pyrimidine rings under different solvent conditions
Authors: Sachar Anand , Gupta Poonam , Gupta Shallu , Sharma R. L.
Published: April 2010

Synthesis of some oxygen, nitrogen, and sulfur based condensed heterocycles by the condensation of dimedone with aromatic monoaldehyde under different solvent conditions has been achieved.
A DFT study on the electronic and redox properties of [X8V14O50]n– (X = SiIV, GeIV, PV, and AsV)
Authors: Janjua Muhammad Ramzan Saeed Ashraf , Su Zhong-Min , Guan Wei , Irfan Ahmad , Muhammad Shabbir , Iqbal Mudassir
Published: April 2010

The electronic and redox properties of the title polyanions have been calculated by means of density functional theory (DFT). These were unrestricted open-shell systems with electronic configuration of d1 of V. In this behalf, energies and compositions of α-LUMO, β-LUMO, α-HOMO, and β-HOMO were also analyzed. First of all, electronic and redox properties of vanadosilicate [Si8V14O50]12– (system 1) were calculated and then SiIV was substituted with GeIV, PV, and AsV for further investigations of systems 2, 3, and 4, respectively. The substitution greatly modifies the electronic properties as α-LUMOs are quite different in all the studied systems. The α-LUMO is mainly composed of V and O in system 1, V and Ge in system 2, V and O in system 3, and As, O, and V in system 4. The alpha HOMO–LUMO energy gaps are greatly reduced in systems 2, 3, and 4 as compared with system 1. The system 4 [As8V14O50]4– has minimal value of total bonding energy, whereas system 2 [Ge8V14O50]12– has maximal, so energetically system 4 is more favourable than the others. After the first reduction, α-LUMO in [Si8V14O50]14– is made up of V and Si, β-LUMO in [Ge8V14O50]13– is concentrated on V and Ge, β-LUMO in [P8V14O50]5– is composed of V only, whereas β-LUMO in [As8V14O50]5– is delocalized over V, O, and As with almost the same contribution of all three atoms.
FINITE NUMBER OF KALUZA–KLEIN MODES, ALL WITH ZERO MASSES
Authors: ERDEM RECAI
Published: April 2010

Kaluza–Klein modes of fermions in a five-dimensional toy model are considered. The number of Kaluza–Klein modes that survive after integration over extra dimensions is finite in this space. Moreover, the extra dimensional piece of the kinetic part of the Lagrangian in this space induces no mass for the higher Kaluza–Klein modes on contrary to the standard lore.
PROBING QUANTUM NONLINEARITIES THROUGH NEUTRINO OSCILLATIONS
Authors: NG WEI KHIM , PARWANI RAJESH R.
Published: April 2010

We investigate potential quantum nonlinear corrections to Dirac's equation through its sub-leading effect on neutrino oscillation probabilities. Working in the plane-wave approximation and in the μ - τ sector, we explore various classes of nonlinearities, with or without an accompanying Lorentz violation. The parameters in our models are first delimited by current experimental data before they are used to estimate corrections to oscillation probabilities. We find that only a small subset of the considered nonlinearities has the potential to be relevant at higher energies and thus possibly detectable in future experiments. A falsifiable prediction of our models is an energy-dependent effective mass-squared, generically involving fractional powers of the energy.
UNIVERSAL PROGRAMMABLE CHAOS GENERATOR: DESIGN AND IMPLEMENTATION ISSUES
Authors: KILIC RECAI
Published: April 2010

Chaos generators are generally designed and implemented by using analog circuit design techniques. Analog implementations require a variety of circuitry that comprises different passive and active electronic components like individual op-amps, comparators, analog multipliers, trigonometric function generators. Anyone who wants to experimentally investigate different structurally chaotic systems has to provide a significant amount of circuit hardware. This process may be hard and time consuming. At this stage, the question to be asked: Is there a unique analog component for implementing a universal analog chaos generator which is capable of generating the chaotic signals of nearly all analog-based chaotic systems. Fortunately, we can now answer this question positively. This analog device is FPAA (Field-Programmable Analog Array). FPAA is the analog equivalent of the FPGA (Field-Programmable Gate Array) used as programmable device in digital signal processing. FPAA is a programmable device for implementing a rich variety of systems including analog functions via dynamic reconfiguration. FPAA can be configured in real time which allows the designers to modify the design or make completely new design in real time. In this paper, we aim to show how FPAA device can be used as universal device for design and implementation of programmable analog chaos generators. For this purpose, we will introduce three FPAA-based design examples: autonomous Chua's circuit, nonautonomous MLC (Murali–Lakshmanan–Chua) circuit and a chaotic system based on a PLL (Phase Locked Loop) model.
BIFURCATIONS OF SNAP-BACK REPELLERS WITH APPLICATION TO BORDER-COLLISION BIFURCATIONS
Authors: GLENDINNING PAUL
Published: April 2010

The bifurcation theory of snap-back repellers in hybrid dynamical systems is developed. Infinite sequences of bifurcations are shown to arise due to the creation of snap-back repellers in noninvertible maps. These are analogous to the cascades of bifurcations known to occur close to homoclinic tangencies for diffeomorphisms. The theoretical results are illustrated with reference to bifurcations in the normal form for border-collision bifurcations.
THE STRUCTURE OF INFINITE PERIODIC AND CHAOTIC HUB CASCADES IN PHASE DIAGRAMS OF SIMPLE AUTONOMOUS FLOWS
Authors: GALLAS JASON A. C.
Published: April 2010

This manuscript reports numerical investigations about the relative abundance and structure of chaotic phases in autonomous dissipative flows, i.e. in continuous-time dynamical systems described by sets of ordinary differential equations. In the first half, we consider flows containing "periodicity hubs", which are remarkable points responsible for organizing the dynamics regularly over wide parameter regions around them. We describe isolated hubs found in two forms of Rössler's equations and in Chua's circuit, as well as surprising infinite hub cascades that we found in a polynomial chemical flow with a cubic nonlinearity. Hub cascades converge orderly to accumulation points lying on specific parameter paths. In sharp contrast with familiar phenomena associated with unstable orbits, hubs and infinite hub cascades always involve stable periodic and chaotic orbits which are, therefore, directly measurable in experiments. In the last part, we consider flows having no hubs but unusual phase diagrams: a cubic polynomial model containing T-points and wide regions of dense chaos, a nonpolynomial model of the Belousov–Zhabotinsky reaction and the Hindmarsh–Rose model of neuronal bursting, both having chaotic phases with "fountains of chaos". The chaotic regions for the flows discussed here are different from what is known for discrete-time maps. This forcefully shows that knowledge about phase diagrams is quite fragmentary and that much work is still needed to classify and to understand them.
INDUCED CURRENT IN QUANTUM AND CLASSICAL RATCHETS
Authors: CARUSELA M. F. , FENDRIK A. J. , ROMANELLI L.
Published: April 2010

In a previous work, we described transport in a classical, externally driven, overdamped ratchet. A transport current arises under two possible conditions: either by increasing the external driving or by adding an optimal amount of noise when the system operates below threshold. In this work, we study the underdamped case. In order to obtain transport it is necessary for the presence of both — a damping mechanism and the lack of symmetries in the potential. Some interesting properties were found: under particular conditions the system could be considered as a mass separation device, and for a specific range of the control parameter, the maximum Lyapunov exponent is reduced when noise is added to the system. We also study analytically and numerically the quantum analog of the same system and explore the conditions to find transport.
SPONTANEOUS SYMMETRY BREAKING AND FIRST-ORDER PHASE TRANSITIONS OF ADSORBED FLUIDS
Authors: SARTARELLI SALVADOR A. , SZYBISZ LESZEK , URRUTIA IGNACIO
Published: April 2010

A density functional formalism is applied to investigate the wetting behavior of Ne confined in slits composed of two parallel solid identical alkaline walls with increasing attractive strength leading to a variety of wetting situations. The study is performed over the complete range of temperature spanned from the triple point Tt up to the critical one Tc of Ne. Attention is paid to the slit's width. It was found that in the case of weaker substrates for temperatures below a certain critical Tsb the density profiles corresponding to the lowest free energy are asymmetric, i.e. exhibit a spontaneous breaking of symmetry. For T > Tsb the phenomenon of symmetry breaking disappears leading to a first-order phase transition.
RANDOM EVOLUTION IN POPULATION DYNAMICS
Authors: CACERES MANUEL O.
Published: April 2010

We present a perturbative formalism to deal with linear random positive maps. We generalize the biological concept of the population growth rate when a Leslie matrix has random elements (i.e. characterizing the macroscopic disorder in the vital parameters). The dominant eigenvalue of which defines the asymptotic dynamics of the mean-value population vector state, is presented as the effective growth rate of a random Leslie model. The problem was reduced to the calculation of the smallest positive root [Formula: see text] of the secular polynomial appearing in the general expression for the mean-value Green function 〈G(z)〉. This nontrivial polynomial can be obtained order by order in terms of a diagrammatic technique built with Terwiel's cumulants, which have carefully been identified in the present work. By understanding how this smallest positive root [Formula: see text] depends on the model of disorder, one can link the asymptotic population dynamics with the statistical properties of the errors (mutations) in the vital parameters. This eigenvalue has the meaning of an effective Perron–Frobenious eigenvalue for a random positive matrix. Analytical (exact and perturbative calculations) results are presented for several models of disorder.
CRITICAL BEHAVIOR AND THRESHOLD OF COEXISTENCE OF A PREDATOR–PREY STOCHASTIC MODEL IN A 2D LATTICE
Authors: ARGOLO C. , OTAVIANO H. , GLERIA IRAM , ARASHIRO EVERALDO , TOMÉ TÂNIA
Published: April 2010

We investigate the critical behavior of a stochastic lattice model describing a predator–prey system. By means of Monte Carlo procedure we simulate the model defined on a regular square lattice and determine the threshold of species coexistence, that is, the critical phase boundaries related to the transition between an active state, where both species coexist and an absorbing state where one of the species is extinct. A finite size scaling analysis is employed to determine the order parameter, order parameter fluctuations, correlation length and the critical exponents. Our numerical results for the critical exponents agree with those of the directed percolation universality class. We also check the validity of the hyperscaling relation and present the data collapse curves.
EARLY WARNINGS FOR CATASTROPHIC SHIFTS IN ECOSYSTEMS: COMPARISON BETWEEN SPATIAL AND TEMPORAL INDICATORS
Authors: DONANGELO RAUL , FORT HUGO , DAKOS VASILIS , SCHEFFER MARTEN , VAN NES EGBERT H.
Published: April 2010

The task of providing leading indicators of catastrophic regime shifts in ecosystems is fundamental in order to design management protocols for those systems. Here we address the problem of lake eutrophication (that is, nutrient enrichment leading to algal blooms) using a simple spatial lake model. We discuss and compare different spatial and temporal early warning signals announcing the catastrophic transition of an oligotrophic lake to eutrophic conditions. In particular, we consider the spatial variance and its associated patchiness of eutrophic water regions. We found that spatial variance increases as the lake approaches the point of transition to a eutrophic state. We also analyze the spatial and temporal early warnings in terms of the amount of information required by each and their respective forewarning times. From the consideration of different remedial procedures that can be followed after these early signals we conclude that some of these indicators are not early enough to avert the undesired impending shift.
SYNCHRONIZATION INDUCED BY INTERMITTENT VERSUS PARTIAL DRIVES IN CHAOTIC SYSTEMS
Authors: ALVAREZ-LLAMOZA O. , COSENZA M. G.
Published: April 2010

We show that the synchronized states of two systems of identical chaotic maps subject to either, a common drive that acts with a probability p in time or to the same drive acting on a fraction p of the maps, are similar. The synchronization behavior of both systems can be inferred by considering the dynamics of a single chaotic map driven with a probability p. The synchronized states for these systems are characterized on their common space of parameters. Our results show that the presence of a common external drive for all times is not essential for reaching synchronization in a system of chaotic oscillators, nor is the simultaneous sharing of the drive by all the elements in the system. Rather, a crucial condition for achieving synchronization is the sharing of some minimal, average information by the elements in the system over long times.
ABOUT THE EFFECTIVENESS OF DIFFERENT METHODS FOR THE ESTIMATION OF THE MULTIFRACTAL SPECTRUM OF NATURAL SERIES
Authors: FIGLIOLA ALEJANDRA , SERRANO EDUARDO , PACCOSI GUSTAVO , ROSENBLATT MARIEL
Published: April 2010

Complex natural systems present characteristics of scalar invariance. This behavior has been experimentally verified and a large related bibliography has been reported. Multifractal Formalism is a way to evaluate this kind of behavior. In the past years, different numerical methods to estimate the multifractal spectrum have been proposed. These methods could be classified into those that originated from the wavelet analysis and others from numerical approximations like the Multifractal Detrended Fluctuation Analysis (MFDFA), proposed by Kantelhardt and Stanley. Recently, S. Jaffard and co-workers proposed the Wavelet Leaders (WL) method that exploits the potential of wavelet analysis and the efficiency of the Multiresolution Wavelet Schema.

In a previous work, we checked that both methods are equivalent for estimating fractal properties in a series from singular measures. Now, we apply MFDFA and WL to natural signals with self-similar structures, but unknown multifractal spectrum. We observe that some differences appear in their respective estimations, particularly when the signals are corrupted with fractional Gaussian noise.
EMBRYONIC SOMITE FORMATION GENERATED BY GENETIC NETWORK OSCILLATIONS WITH NOISE
Authors: MAZZITELLO KARINA I. , ARIZMENDI CONSTANCIO M. , SALAS BRITO ALVARO L. , HENTSCHEL HILARY G. E.
Published: April 2010

In most vertebrate species, the body axis is generated by the formation of repeated transient structures called somites. This spatial periodicity in somitogenesis has been related to the genetic network oscillations in certain mRNAs and their associated gene products in the cells forming the presomitic mesoderm. The current molecular view of the mechanism underlying these oscillations involves negative-feedback regulation at transcriptional and translational levels. The spatially periodic nature of somite formation suggests that the genetic network involved must display intracellular oscillations that interact with a longitudinal positional information gradient, called determination front, down the axis of vertebrate embryos to create this spatial patterning. Here, we consider a simple model for diploid cells based on this current biological picture considering gene regulation as a noisy process relevant in a real developmental situation and study its consequences for somitogenesis. Comparison is made with the known properties of somite formation in the zebrafish embryo.
ENTROPY CORRELATION DISTANCE METHOD APPLIED TO STUDY CORRELATIONS BETWEEN THE GROSS DOMESTIC PRODUCT OF RICH COUNTRIES
Authors: AUSLOOS MARCEL , MIŚKIEWICZ JANUSZ
Published: April 2010

The Theil index is much used in economy and finance; it looks like the Shannon entropy, but pertains to event values rather than to their probabilities. Any time series can be remapped through the Theil index. Correlation coefficients can be evaluated between the new time series, thereby allowing to study their mutual statistical distance — to be contrasted to the usual correlation distance measure for the primary time series. As an example this entropy-like correlation distance method (ECDM) is applied to the Gross Domestic Product of 20 rich countries in order to test some economy globalization process. Hierarchical distances allow to construct (i) a linear network, (ii) a Locally Minimal Spanning Tree. The role of time averaging in finite size windows is illustrated and discussed. It is also shown that the mean distance between the most developed countries, was decreasing since 1960 till 2000, which we consider to be a proof of globalization of the economy for these countries.
DYNAMICS OF A CLASSICAL PARTICLE EXTERNALLY DRIVEN ON A MAGNETIC BUBBLE LATTICE
Authors: SAGUÉS FRANCESC , SOBA ALEJANDRO , TIERNO PIETRO
Published: April 2010

We study the motion of a classical paramagnetic particle externally driven above a hexagonal lattice of ferromagnetic bubbles. The presented simulations reproduce recently observed trajectories of micron-size colloidal particles externally driven above a uniaxial garnet film [Tierno et al., 2007a].
NONLINEAR TIME SERIES INTO COMPLEX NETWORKS SCHEME
Authors: REDELICO FRANCISCO O. , PROTO ARACELI N.
Published: April 2010

Time series analysis is a fundamental tool for a wide variety of fields. Different methods have been proposed to extract information about the underlying dynamics (basically nonlinear) contained inside the time series [Albert & Barabási, 2002]. In this contribution, a new method for mapping nonlinear time series into complex networks is studied using simulated data.
CLASSIFICATION AND IDENTIFICATION OF FUNGAL SEQUENCES USING CHARACTERISTIC RESTRICTION ENDONUCLEASE CUT ORDER
Authors: SENGUPTA RAJIB , BASTOLA DHUNDY R. , ALI HESHAM H.
Published: April 2010

Restriction Fragment Length Polymorphism (RFLP) is a powerful molecular tool that is extensively used in the molecular fingerprinting and epidemiological studies of microorganisms. In a wet-lab setting, the DNA is cut with one or more restriction enzymes and subjected to gel electrophoresis to obtain signature fragment patterns, which is utilized in the classification and identification of organisms. This wet-lab approach may not be practical when the experimental data set includes a large number of genetic sequences and a wide pool of restriction enzymes to choose from. In this study, we introduce a novel concept of Enzyme Cut Order — a biological property-based characteristic of DNA sequences which can be defined and analyzed computationally without any alignment algorithm. In this alignment-free approach, a similarity matrix is developed based on the pairwise Longest Common Subsequences (LCS) of the Enzyme Cut Orders. The choice of an ideal set of restriction enzymes used for analysis is augmented by using genetic algorithms. The results obtained from this approach using internal transcribed spacer regions of rDNA from fungi as the target sequence show that the phylogenetically-related organisms form a single cluster and successful grouping of phylogenetically close or distant organisms is dependent on the choice of restriction enzymes used in the analysis. Additionally, comparison of trees obtained with this alignment-free and the legacy method revealed highly similar tree topologies. This novel alignment-free method, which utilizes the Enzyme Cut Order and restriction enzyme profile, is a reliable alternative to local or global alignment-based classification and identification of organisms.
SIGMA: A SET-COVER-BASED INEXACT GRAPH MATCHING ALGORITHM
Authors: MONGIOVÌ MISAEL , DI NATALE RAFFAELE , GIUGNO ROSALBA , PULVIRENTI ALFREDO , FERRO ALFREDO , SHARAN RODED
Published: April 2010

Network querying is a growing domain with vast applications ranging from screening compounds against a database of known molecules to matching sub-networks across species. Graph indexing is a powerful method for searching a large database of graphs. Most graph indexing methods to date tackle the exact matching (isomorphism) problem, limiting their applicability to specific instances in which such matches exist. Here we provide a novel graph indexing method to cope with the more general, inexact matching problem. Our method, SIGMA, builds on approximating a variant of the set-cover problem that concerns overlapping multi-sets. We extensively test our method and compare it to a baseline method and to the state-of-the-art Grafil. We show that SIGMA outperforms both, providing higher pruning power in all the tested scenarios.
COMBINATORIAL RECONSTRUCTION OF HALF-SIBLING GROUPS FROM MICROSATELLITE DATA
Authors: SHEIKH SAAD I. , BERGER-WOLF TANYA Y. , KHOKHAR ASHFAQ A. , CABALLERO ISABEL C. , ASHLEY MARY V. , CHAOVALITWONGSE WANPRACHA , CHOU CHUN-AN , DASGUPTA BHASKAR
Published: April 2010

While full-sibling group reconstruction from microsatellite data is a well-studied problem, reconstruction of half-sibling groups is much less studied, theoretically challenging, and computationally demanding. In this paper, we present a formulation of the half-sibling reconstruction problem and prove its APX-hardness. We also present exact solutions for this formulation and develop heuristics. Using biological and synthetic datasets we present experimental results and compare them with the leading alternative software COLONY. We show that our results are competitive and allow half-sibling group reconstruction in the presence of polygamy, which is prevalent in nature.
The role of mantle hydration in continental crust recycling in the wedge region
Authors: Meda Marco , Marotta Anna Maria , Spalla Maria Iole
Published: April 2010

In orogenic belts high pressure–low temperature (HP–LT) metamorphism can widely affect units derived from both the oceanic and the continental lithosphere. In order to verify whether high
P
/
T
(pressure/temperature) ratios recorded in the continental lithosphere can result from tectonic erosion, ablative subduction and recycling in the mantle wedge, we implemented a 2D numerical model to simulate oceanic subduction beneath a continent. Particular attention is paid to the role played by mantle hydration within the continental crust recycled in the wedge region. A comparison between hydrated and non-hydrated models highlights that hydration is fundamental in allowing the recycling of crustal material at shallow depths (≤150 km for a convergence rate of 1 cm year
−1
), making the uprising and exhumation of buried crustal material during active subduction possible. The recycled crustal material can originate from any crustal level. The
T
max
and
P
max
distributions within the final marker configuration show that crustal recycling induces the coupling of volumes that reached different depths during their paths in the corner flow. To verify the reliability of this model we compare predictions with natural geological data from the Austroalpine Sesia–Lanzo Zone (SLZ), the largest eclogite-facies crustal fragment of early Alpine age and whose Alpine tectonic evolution has been interpreted as compatible with a cycle of burial at depth and exhumation during active subduction of the oceanic lithosphere. The relationships between natural
P
–
T
estimates and predicted
P
–
T
values show that the simulated geodynamic scenario generates a thermal regime coherent with that affecting the subducted continental crust of the SLZ, which may have been stable for a long time during Alpine subduction, allowing the SLZ rocks to accomplish their burial and exhumation path under an active subduction regime.