692 research outputs found
Automatised classification of WISE sources: first results, future prospects
No full textComputational astrophysic
Econometric Tools for Detection of Collusion Equilibrium in the Industry
No full textThe article presents the notion of detection of overt or tacit collusion equilibrium in the context of choice of the appropriate econometric method, which is determined by the amount of information that the observer possesses. There has been shown one of the collusion markers coherent with an equilibrium of the proper model of strategic interaction – the presence of structural disturbances in the price process variance for phases of collusion and competition. The Markov Switching Model with switching of variance regimes has been proposed as a proper theoretical method detecting that type of changes without prior knowledge of switching moments. In order to verify the effectiveness of the method it has been applied to a series of lysine market prices throughout and after termination of its manufacturers’ collusion.explicit and tacit collusion, collusive equilibrium, cartel detection, lysine, price variance, Markov switching model.
Neural Network Time-Series Classifiers for Gravitational-Wave Searches in Single-Detector Periods
No full textThis chapter contains a summary of the paper in Ref. [ 1], in which the
challenges in detecting gravitational-wave (GW) signals, especially when only one detector is operating, are discussed. The single detector case is particularly difficult to analyse since a very useful tool to distinguish astrophysical signals from instrumental glitches cannot be used, i.e. the temporal coincidence between detectors. Neural network classifiers are explored, including convolutional neural networks, temporal convolutional networks, and inception time, specifically tailored for time-series data processing. The classifiers are trained on a subset of data from the LIGO Livingston detector during the first observing run (O1) to identify segments containing binary black hole merger signatures. Their performances are evaluated and compared. Subsequently, these trained classifiers are applied to the remaining O1 data, particularly focusing on single-detector times, with the most promising candidate from this search identified at the time 2016-01-04 12:24:17 UTC
Cartel in the Indian cement industry: An attempt to identify it
No full textThis article is devoted to the problem of the detection of overt or tacit collusion equilibrium in the context of the choice of the appropriate econometric method, a choice that is determined by the amount of information that the observer possesses. The author addresses this problem in two steps. First, to provide a theoretical background, he uses a collusion marker based on structural disturbances in a price process'; variance. Then, he applies a Markov switching model with switching in variance regimes. The author considers this method adequate and coherent with the problem structure and the research objective, and useful for assessing the functionality of the collusion marker he uses. He uses the model to examine the Indian cement industry in the period 1994-2009 and finds some objective indications of collusion and competition phases. These phases are confirmed by certain historical facts as well as by numerous research articles
Moments of inertia for neutron and strange stars: Limits derived for the Crab pulsar
No full textRecent estimates of the properties of the Crab nebula are used to
derive constraints on the moment of inertia, mass and radius of the
pulsar. To this purpose, we employ an approximate formula combining
these three parameters.
Our “empirical formula” , where ,
is based on numerical results obtained for thirty theoretical
equations of state of dense matter.
The functions for neutron stars
and strange stars are qualitatively different. For neutron stars
for (valid
for )
and for .
For strange
stars (not valid for strange stars
with crust and ).
We obtain also an approximate expression for the maximum moment of
inertia ,
where , valid for
both neutron stars and strange stars.
Applying our formulae to the evaluated values of ICrab,
we derive constraints on the mass and radius of the pulsar.
A very conservative evaluation of the expanding nebula mass,
, yields and
10–14 . Setting the most recent evaluation
(“central value”)
rules out most of the existing equations
of state, leaving only the stiffest ones: ,
14–15
Denoising gravitational-wave signals from binary black holes with dilated convolutional autoencoder
No full textInternational audienceBroadband frequency output of gravitational-wave detectors is a non-stationary and non-Gaussian time series data stream dominated by noise populated by local disturbances and transient artifacts, which evolve on the same timescale as the gravitational-wave signals and may corrupt the astrophysical information. We study a denoising algorithm dedicated to expose the astrophysical signals by employing a convolutional neural network in the encoder-decoder configuration, i.e. apply the denoising procedure of coalescing binary black hole signals in the publicly available LIGO O1 time series strain data. The denoising convolutional autoencoder neural network is trained on a dataset of simulated astrophysical signals injected into the real detector's noise and a dataset of detector noise artifacts ("glitches"), and its fidelity is tested on real gravitational-wave events from O1 and O2 LIGO-Virgo observing runs
Synthesis and Recognition Properties of Higher Order Tetrathiafulvalene (Ttf) Calix N Pyrroles (N=4-6)
No full textTwo new benzoTTF-annulated calix[n]pyrroles (n = 5 and 6) were synthesized via a one-step acid catalyzed condensation reaction and fully characterized via single crystallographic analyses. As compared to the known tetra-TTF annulated calix[4]pyrrole, which is also produced under the conditions of the condensation reaction, the expanded calix[n]pyrroles (n = 5 and 6) are characterized by a larger cavity size and a higher number of TTF units (albeit the same empirical formula). Analysis of the binding isotherms obtained from UV-Vis spectroscopic titrations carried out in CHCl3 in the presence of both anionic (Cl-, Br-, I-, CH3COO-, H2PO4-, and HSO4-) and neutral (1,3,5-trinitrobenzene (TNB) and 2,4,6-trinitrotoluene (TNT)) substrates revealed that as a general rule the calix[6]pyrrole derivative proved to be the most efficient molecular receptor for anions, while the calix[4]pyrrole congener proves most effective for the recognition of TNB and TNT. These findings are rationalized in terms of the number of electron rich TTF subunits and NH hydrogen bond donor groups within the series, as well as an ability to adopt conformations suitable for substrate recognition, and are supported by solid state structural analyses.National Science Foundation CHE 1057904, 0741973Robert A. Welch Foundation F-1018Danish Natural Science Research Council (FNU) 272-08-0047, 11-106744WCU (World Class University) program of Korea R32-2010-10217-0Villum FoundationChemistr
Surface gravity of neutron stars and strange stars
No full textThe upper bound on the value of the surface gravity,
gs, for neutron stars with equations of state respecting
, is derived. This bound is inversely
proportional to the maximum allowable mass Mmax, and it
reads . It implies an absolute
upper bound if one uses the lower bound on the neutron mass measured recently in 4U1700-37, . A correlation between gs and
the compactness parameter for baryonic stars is
analyzed. The properties of gs of strange quark stars
and its upper bounds are discussed using the scaling properties of
the strange-star models
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