1,136 research outputs found
Symmetric Jacobians
This article is about polynomial maps with a certain symmetry and/or
antisymmetry in their Jacobians, and whether the Jacobian Conjecture is
satisfied for such maps, or whether it is sufficient to prove the Jacobian
Conjecture for such maps.
For instance, we show that it suffices to prove the Jacobian conjecture for
polynomial maps x + H over C such that JH satisfies all symmetries of the
square, where H is homogeneous of arbitrary degree d >= 3.Comment: 18 pages, minor corrections, grayscale eepic boxes have been replaced
by colorful tikz boxe
On the theory of Gordan-Noether on homogeneous forms with zero Hessian (Improved version)
We give a detailed proof for Gordan-Noether's results in "Ueber die
algebraischen Formen, deren Hesse'sche Determinante identisch verschwindet"
published in 1876 in Mathematische Annahlen. C. Lossen has written a paper in a
similar direction as the present paper, but did not provide a proof for every
result. In our paper, every result is proved. Furthermore, our paper is
independent of Lossen's paper and includes a considerable number of new
observations.
An earlier version of this paper has been printed in Proceedings of the
School of Science of Tokai University, Vol.49, Mar. 2014. In this version, a
serious error has been corrected and some new results have been added
Booms and busts in China's stock market: Estimates based on fundamentals
This paper empirically models China’s stock prices using conventional fundamentals: corporate earnings, risk-free interest rate, and a proxy for equity risk premium. It uses the estimated longrun stock price misalignments to date booms and busts, and analyses equity market reforms and excess liquidity as potential drivers of these stock price misalignments. Our results show that China’s equity prices can be reasonable well modelled using fundamentals, but that various booms and busts can be identified. Policy actions, either taking the form of deposit rate changes, equity market reforms or excess liquidity, seem to have significantly contributed to these misalignments. JEL Classification: G12, G18China, Equity market, liquidity, reforms, Stock price
Comparison of different exoplanet mass detection limit methods using a sample of main-sequence intermediate-type stars
The radial velocity (RV) technique is a powerful tool for detecting
extrasolar planets and deriving mass detection limits that are useful for
constraining planet pulsations and formation models. Detection limit methods
must take into account the temporal distribution of power of various origins in
the stellar signal. These methods must also be able to be applied to large
samples of stellar RV time series We describe new methods for providing
detection limits. We compute the detection limits for a sample of ten main
sequence stars, which are of G-F-A type, in general active, and/or with
detected planets, and various properties. We use them to compare the
performances of these methods with those of two other methods used in the
litterature. We obtained detection limits in the 2-1000 day period range for
ten stars. Two of the proposed methods, based on the correlation between
periodograms and the power in the periodogram of the RV time series in specific
period ranges, are robust and represent a significant improvement compared to a
method based on the root mean square of the RV signal. We conclude that two of
the new methods (correlation-based method and local power analysis, i.e. LPA,
method) provide robust detection limits, which are better than those provided
by methods that do not take into account the temporal sampling.Comment: 18 pages, 15 figures Accepted in Astronomy & Astrophysic
Booms and busts in China's stock market : estimates based on fundamentals
This paper empirically models China’s stock prices using conventional fundamentals: corporate earnings, risk-free interest rate, and a proxy for equity risk premium. It uses the estimated long-run stock price misalignments to date booms and busts, and analyses equity market reforms and excess liquidity as potential drivers of these stock price misalignments. Our results show that China’s equity prices can be reasonable well modelled using fundamentals, but that various booms and busts can be identified. Policy actions, either taking the form of deposit rate changes, equity market reforms or excess liquidity, seem to have significantly contributed to these misalignment
Fab glycosylation of immunoglobulin G does not associate with improvement of rheumatoid arthritis during pregnancy
Background: Changes in immunoglobulin G (IgG) constant domain (Fc) glycosylation are associated with changes in rheumatoid arthritis (RA) disease activity in response to pregnancy. Here, we sought to determine whether the same holds true for variable domain (Fab) glycosylation. Methods: IgGs were captured from RA and control sera obtained before (RA only), during and after pregnancy, followed by Fc and Fab separation, glycan release, and mass spectrometric detection. In parallel,
Virtual volatility
We introduce the concept of virtual volatility. This simple but new measure
shows how to quantify the uncertainty in the forecast of the drift component of
a random walk. The virtual volatility also is a useful tool in understanding
the stochastic process for a given portfolio. In particular, and as an example,
we were able to identify mean reversion effect in our portfolio. Finally, we
briefly discuss the potential practical effect of the virtual volatility on an
investor asset allocation strategy.Comment: 15 pages, 2 figures, elsart.cls, Accepted to Physica A. Added few
comments that clarify data used for empirical wor
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