359 research outputs found
Multi-scale correlations in different futures markets
In the present work we investigate the multiscale nature of the correlations
for high frequency data (1 minute) in different futures markets over a period
of two years, starting on the 1st of January 2003 and ending on the 31st of
December 2004. In particular, by using the concept of "local" Hurst exponent,
we point out how the behaviour of this parameter, usually considered as a
benchmark for persistency/antipersistency recognition in time series, is
largely time-scale dependent in the market context. These findings are a direct
consequence of the intrinsic complexity of a system where trading strategies
are scale-adaptive. Moreover, our analysis points out different regimes in the
dynamical behaviour of the market indices under consideration.Comment: 14 pages and 25 figure
Eikonal representation in the momentum-transfer space
By means of empirical fits to the differential cross section data on pp and
p(bar)p elastic scattering, above 10 GeV (center-of-mass energy), we determine
the eikonal in the momentum - transfer space (q^2- space). We make use of a
numerical method and a novel semi-analytical method, through which the
uncertainties from the fit parameters can be propagated up to the eikonal in
the - space. A systematic study of the effect of the experimental
information at large values of the momentum transfer is developed and discussed
in detail. We present statistical evidence that the imaginary part of the
eikonal changes sign in the q^2- space and that the position of the zero
decreases as the energy increases; after the position of the zero, the eikonal
presents a minimum and then goes to zero through negative values. We discuss
the applicability of our results in the phenomenological context, outlining
some connections with nonperturbative QCD. A short review and a critical
discussion on the main results concerning "model-independent" analyses are also
presented.Comment: 18 pages, 17 figures, 4 tables, svjour.cls. Revised discussion on the
proton's electromagnetic form factor and references added. To appear in Eur.
Phys. J.
Quantifying bid-ask spreads in the Chinese stock market using limit-order book data: Intraday pattern, probability distribution, long memory, and multifractal nature
The statistical properties of the bid-ask spread of a frequently traded
Chinese stock listed on the Shenzhen Stock Exchange are investigated using the
limit-order book data. Three different definitions of spread are considered
based on the time right before transactions, the time whenever the highest
buying price or the lowest selling price changes, and a fixed time interval.
The results are qualitatively similar no matter linear prices or logarithmic
prices are used. The average spread exhibits evident intraday patterns
consisting of a big L-shape in morning transactions and a small L-shape in the
afternoon. The distributions of the spread with different definitions decay as
power laws. The tail exponents of spreads at transaction level are well within
the interval and that of average spreads are well in line with the
inverse cubic law for different time intervals. Based on the detrended
fluctuation analysis, we found the evidence of long memory in the bid-ask
spread time series for all three definitions, even after the removal of the
intraday pattern. Using the classical box-counting approach for multifractal
analysis, we show that the time series of bid-ask spread does not possess
multifractal nature.Comment: 8 EPJ pages including 7 eps figure
Thermal conductivities under high pressure in core samples from IODP NanTroSEIZE drilling site C0001
Handley Donaldson
31-1Revolutionary PensionsReport : Petition of H. Donaldson. [584] Indian hostilities; 1811; Kaskaskia in Illinois.1850-8
Acoustic and mechanical properties of Nankai accretionary prism core samples
International audienceWe studied undeformed sediment and accreted strata recently recovered by Ocean Drilling Program/Integrated Ocean Drilling Program (ODP/IODP) drilling in Nankai Trough convergent margin to unravel the changes in physical properties from initial deposition to incipient deformation. We have derived acoustic (Vp) and mechanical (uniaxial poroelastic compliance, compaction amplitude) properties of samples from various drill sites along the Muroto (ODP 1173) and Kii transects (IODP C0001, C0002, C0006, and C0007) from isotropic loading tests where confining and pore pressure were independently applied. We quantified the dependence of Vp on both effective (Peff) and confining (Pc) pressure, which can be used to correct atmospheric pressure measurements of Vp. Experimental Vp obtained on core samples extrapolated to in situ conditions are slightly higher than logging-derived velocities, which can be attributed either to velocity dispersion or to the effect of large-scale faults and weak zones on waves with longer wavelength. In the high-porosity (30%-60%) tested sediments, velocities are controlled at first order by porosity and not by lithology, which is in agreement with our static measurements of drained framework incompressibility, much smaller than fluid incompressibility. Rather than framework incompressibility, shear modulus is probably the second-order control on Vp, accounting for most of the difference between actual Vp and the prediction by Wood's (1941) suspension model. We also quantified the mechanical state of Nankai samples in terms of anisotropy, diagenesis, and consolidation. Both acoustic and mechanical parameters reveal similar values in vertical and horizontal directions, attesting to the very low anisotropy of the tested material. When considering the porous samples of the Upper Shikoku Basin sediments (Site 1173) as examples of diagenetically cemented material, several mechanical and acoustic attributes appeared as reliable experimental indicators of the presence of intergrain cementation. We also detected incipient cementation in samples from IODP Site C0001 (accretionary prism unit). In terms of consolidation, we distinguished two classes of material response (shallow, deformable samples and deep, hardly deformable ones) based on the amount of compaction upon application of a Peff large with respect to the inferred in situ value, with a transition that might be related to a critical porosity
Anelastic strain recovery reveals extension across SW Japan subduction zone
Sediment dominated convergent margins typically
record substantial horizontal shortening often associated
with great earthquakes. The convergent margin south of
Japan is arguably one of the most extensively investigated
margins and previous studies have documented extensive
evidence for accretion and horizontal shortening. Here, we
show results from anelastic strains recovered from three
partially lithified sediment samples (40~ porosities)
across the southwest Japan accretionary prism and
propose that the margin is dominated by horizontal
extension rather than compression. The anelastic strain
results are also consistent with stress directions interpreted
from two independent techniques - bore hole breakout
orientations and core-scale fault data. We interpret this
unexpected result to reflect geologically recent underthrusting
of a thick sediment package and concomitant
weakening of the decollement
The thickness of subduction plate boundary faults from the seafloor into the seismogenic zone
The thickness of an active plate boundary fault is an important parameter for understanding
the strength and spatial heterogeneity of fault behavior. We have compiled direct
measurements of the thickness of subduction thrust faults from active and ancient examples
observed by ocean drilling and fi eld studies in accretionary wedges. We describe a general
geometric model for subduction thrust décollements, which includes multiple simultaneously
active, anastomosing fault strands tens of meters thick. The total thickness encompassing all
simultaneously active strands increases to ~100â350 m at ~1â2 km below seafl oor, and this
thickness is maintained down to a depth of ~15 km. Thin sharp faults representing earthquake
slip surfaces or other discrete slip events are found within and along the edges of the tens-ofmeters-
thick fault strands. Although fl attening, primary inherited chaotic fabrics, and fault
migration through subducting sediments or the frontal prism may build mélange sections that
are much thicker (to several kilometers), this thickness does not describe the active fault at
any depth. These observations suggest that models should treat the subduction thrust plate
boundary fault as <1â20 cm thick during earthquakes, with a concentration of postseismic
and interseismic creep in single to several strands 5â35 m thick, with lesser distributed interseismic
deformation in stratally disrupted rocks surrounding the fault strands
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