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Palaeolimnology of Lake Sapanca and identification of historic earthquake signals, Northern Anatolian Fault Zone (Turkey)
Lake Sapanca is located on a strand of the Northern Anatolian Fault Zone (NAFZ, Turkey), where a series of strong earthquakes (Ms >6.0) have occurred over the past hundred years. Identifying prehistoric
earthquakes in and around Lake Sapanca is key to a better understanding of plate movements along the
NAFZ. This study contributes to the development of palaeolimnological tools to identify past earthquakes
in Lake Sapanca. To this end several promising proxies were investigated, specifically lithology, magnetic
susceptibility, grain size (thin-section and laser analysis), geochemistry, pollen concentration, diatom
assemblages, 137Cs and 210Pb. Sedimentological indicators provided evidence for reworked, turbidite-like
or homogeneous facies (event layers) in several short cores (<45 cm). Other indicators of sediment input
and the historical chronicles available for the area suggest that three of these event layers likely originated
from the AD 1957, 1967 and 1999 earthquakes. Recent changes in sediment deposition and nutrient
levels have also been identified, but are probably not related to earthquakes. This study demonstrates
that a combination of indicators can be used to recognize earthquake-related event layers in cores that encompass a longer period of time
The magnetic field of the double-lined spectroscopic binary system HD 5550
(Abridged) In the framework of the BinaMicS project, we have begun a study of
the magnetic properties of a sample of intermediate-mass and massive
short-period binary systems, as a function of binarity properties. We report in
this paper the characterisation of the magnetic field of HD 5550, a
double-lined spectroscopic binary system of intermediate-mass, using
high-resolution spectropolarimetric Narval observations of HD 5550. We first
fit the intensity spectra using Zeeman/ATLAS9 LTE synthetic spectra to estimate
the effective temperatures, microturbulent velocities, and the abundances of
some elements of both components, as well as the light-ratio of the system. We
then fit the least-square deconvolved profiles to determine the radial and
projected rotational velocities of both stars. We then analysed the shape and
evolution of the LSD profiles using the oblique rotator model to
characterise the magnetic fields of both stars.
We confirm the Ap nature of the primary, previously reported in the
literature, and find that the secondary displays spectral characteristics
typical of an Am star. While a magnetic field is clearly detected in the lines
of the primary, no magnetic field is detected in the secondary, in any of our
observation. If a dipolar field were present at the surface of the Am star, its
polar strength must be below 40 G. The faint variability observed in the Stokes
profiles of the Ap star allowed us to propose a rotation period of
d, close to the orbital period (6.82 d),
suggesting that the star is synchronised with its orbit. By fitting the
variability of the profiles, we propose that the Ap component hosts a
dipolar field inclined with the rotation axis at an angle
and a polar strength G. The field strength is
the weakest known for an Ap star.Comment: 13 pages, 12 figures, accepted for publication in Astronomy &
Astrophysic
Exploring Outliers in Crowdsourced Ranking for QoE
Outlier detection is a crucial part of robust evaluation for crowdsourceable
assessment of Quality of Experience (QoE) and has attracted much attention in
recent years. In this paper, we propose some simple and fast algorithms for
outlier detection and robust QoE evaluation based on the nonconvex optimization
principle. Several iterative procedures are designed with or without knowing
the number of outliers in samples. Theoretical analysis is given to show that
such procedures can reach statistically good estimates under mild conditions.
Finally, experimental results with simulated and real-world crowdsourcing
datasets show that the proposed algorithms could produce similar performance to
Huber-LASSO approach in robust ranking, yet with nearly 8 or 90 times speed-up,
without or with a prior knowledge on the sparsity size of outliers,
respectively. Therefore the proposed methodology provides us a set of helpful
tools for robust QoE evaluation with crowdsourcing data.Comment: accepted by ACM Multimedia 2017 (Oral presentation). arXiv admin
note: text overlap with arXiv:1407.763
Fractal Markets Hypothesis and the Global Financial Crisis: Scaling, Investment Horizons and Liquidity
We investigate whether fractal markets hypothesis and its focus on liquidity
and invest- ment horizons give reasonable predictions about dynamics of the
financial markets during the turbulences such as the Global Financial Crisis of
late 2000s. Compared to the mainstream efficient markets hypothesis, fractal
markets hypothesis considers financial markets as com- plex systems consisting
of many heterogenous agents, which are distinguishable mainly with respect to
their investment horizon. In the paper, several novel measures of trading
activity at different investment horizons are introduced through scaling of
variance of the underlying processes. On the three most liquid US indices -
DJI, NASDAQ and S&P500 - we show that predictions of fractal markets hypothesis
actually fit the observed behavior quite well.Comment: 11 pages, 3 figure
The Level-0 Muon Trigger for the LHCb Experiment
A very compact architecture has been developed for the first level Muon
Trigger of the LHCb experiment that processes 40 millions of proton-proton
collisions per second. For each collision, it receives 3.2 kBytes of data and
it finds straight tracks within a 1.2 microseconds latency. The trigger
implementation is massively parallel, pipelined and fully synchronous with the
LHC clock. It relies on 248 high density Field Programable Gate arrays and on
the massive use of multigigabit serial link transceivers embedded inside FPGAs.Comment: 33 pages, 16 figures, submitted to NIM
Microstructure Effects on Daily Return Volatility in Financial Markets
We simulate a series of daily returns from intraday price movements initiated
by microstructure elements. Significant evidence is found that daily returns
and daily return volatility exhibit first order autocorrelation, but trading
volume and daily return volatility are not correlated, while intraday
volatility is. We also consider GARCH effects in daily return series and show
that estimates using daily returns are biased from the influence of the level
of prices. Using daily price changes instead, we find evidence of a significant
GARCH component. These results suggest that microstructure elements have a
considerable influence on the return generating process.Comment: 15 pages, as presented at the Complexity Workshop in Aix-en-Provenc
Charge Transport in Non-Irradiated and Irradiated Silicon Diodes
A model describing the transport of charge carriers generated in silicon detectors (standard planar float zone and MESA diodes) by ionizing particles is presented. The current pulse response induced by and particles in non-irradiated detectors and detectors irradiated up to fluences particles/cm is reproduced through this model: i) by adding a small n-type region 15 m deep on the side for the standard planar float zone detectors at fluences beyond the n to p-type inversion and ii) for the MESA detectors, by considering one dead layer 14 m deep (observed experimentally) on each side, and introducing a second (delayed) component. For both types of detectors, the model gives mobilities decreasing linearily up to fluences of about particles/cm and converging, beyond, to saturation values of about 1000 cm/Vs and 455 cm/Vs for electrons and holes, respectively. At a fluence particles/cm, charge collection deficits of about 13\% for particles, 25\% for particles incident on the front and 35\% for particles incident on the back of the detector are found for both type of diodes
Study of charge Transport in Silicon Detectors: Non-Irradiated and Irradiated
The electrical characteristics of silicon detectors (standard planar float zone and MESA detectors) as a function of the particle fluence can be extracted by the application of a model describing the transport of charge carriers generated in the detectors by ionizing particles. The current pulse response induced by and particles in non-irradiated detectors and detectors irradiated up to fluences particles/cm is reproduced via this model: i) by adding a small n-type region 15 m deep on the side for the detectors at fluences beyond the n to p-type inversion and ii) for the MESA detectors, by considering one additional dead layer of 14 m (observed experimentally) on each side of the detector, and introducing a second (delayed) component to the current pulse response. For both types of detectors, the model gives mobilities decreasing linearily up to fluences of about particles/cm and converging, beyond, to saturation values of about 1050 cm/Vs and 450 cm/Vs for electrons and holes, respectively. At a fluence particles/cm (corresponding to about ten years of operation at the CERN-LHC), charge collection deficits of about 14\% for particles, 25\% for particles incident on the front and 35\% for particles incident on the back of the detector are found for both type of detectors
Optimizing a Certified Proof Checker for a Large-Scale Computer-Generated Proof
In recent work, we formalized the theory of optimal-size sorting networks
with the goal of extracting a verified checker for the large-scale
computer-generated proof that 25 comparisons are optimal when sorting 9 inputs,
which required more than a decade of CPU time and produced 27 GB of proof
witnesses. The checker uses an untrusted oracle based on these witnesses and is
able to verify the smaller case of 8 inputs within a couple of days, but it did
not scale to the full proof for 9 inputs. In this paper, we describe several
non-trivial optimizations of the algorithm in the checker, obtained by
appropriately changing the formalization and capitalizing on the symbiosis with
an adequate implementation of the oracle. We provide experimental evidence of
orders of magnitude improvements to both runtime and memory footprint for 8
inputs, and actually manage to check the full proof for 9 inputs.Comment: IMADA-preprint-c
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