Experimental effects on dynamics and thermodynamics in nuclear reactions on the symmetry energy as seen by the CHIMERA 4π\pi detector

Heavy ion collisions have been widely used in the last decade to constraint the parameterizations of the symmetry energy term of nuclear equation of state (EOS) for asymmetric nuclear matter as a function of baryonic density. In the Fermi energy domain one is faced with variations of the density within a narrow range of values around the saturation density $\rho_0$=0.16 fm$^{-3}$ down towards sub-saturation densities. The experimental observables which are sensitive to the symmetry energy are constructed starting from the detected light particles, clusters and heavy fragments that, in heavy ion collisions, are generally produced by different emission mechanisms at different stages and time scales of the reaction. In this review the effects of dynamics and thermodynamics on the symmetry energy in nuclear reactions are discussed and characterized using an overview of the data taken so far with the CHIMERA multi-detector array.Comment: 21 pages, 25 figures. Review to appear in EPJA special volume on nuclear symmetry energ

Noise-induced dephasing of an ac-driven Josephson junction

We consider phase-locked dynamics of a Josephson junction driven by finite-spectral-linewidth ac current. By means of a transformation, the effect of frequency fluctuations is reduced to an effective additive noise, the corresponding (large) dephasing time being determined, in the logarithmic approximation, by the Kramers' expression for the lifetime. For sufficiently small values of the drive's amplitude, direct numerical simulations show agreement of the dependence of the dephasing activation energy on the ac-drive's spectral linewidth and amplitude with analytical predictions. Solving the corresponding Fokker-Planck equation analytically, we find a universal dependence of a critical value of the effective phase-diffusion parameter on the drive's amplitude at a point of a sharp transition from the phase-locked state to an unlocked one. For large values of the drive amplitude, saturation and subsequent decrease of the activation energy are revealed by simulations, which cannot be accounted for by the perturbative analysis. The same new effect is found for a previously studied case of ac-driven Josephson junctions with intrinsic thermal noise. The work was performed in the framework of a cooperation agreement between Consiglio Nazionale di Ricerca (Italy) and the Israeli Ministry of Science and Technology.Comment: latex text file and six eps figure files. Physical Review E, in pres

The quality of price formation at market openings and closings: evidence from the Nasdaq stock market

Central counterparties (CCPs) have increasingly become a cornerstone of financial markets infrastructure. We present a model where trades are time-critical, liquidity is limited and there is limited enforcement of trades. We show a CCP novating trades implements efficient trading behaviour. It is optimal for the CCP to face default losses to achieve the efficient level of trade. To cover these losses, the CCP optimally uses margin calls, and, as the default problem becomes more severe, also requires default funds and then imposes position limits

The Chemical Composition of {\tau} Ceti and Possible Effects on Terrestrial Planets

{\tau} Ceti (HD10700), a G8 dwarf with solar mass of 0.78, is a close (3.65 pc) sun-like star where 5 possibly terrestrial planet candidates (minimum masses of 2, 3.1, 3.5, 4.3, and 6.7 Earth masses) have recently been discovered. We report abundances of 23 elements using spectra from the MIKE spectrograph on Magellan. Using stellar models with the abundances determined here, we calculate the position of the classical habitable zone with time. At the current best fit age, 7.63 Gy, up to two planets (e and f) may be in the habitable zone, depending on atmospheric properties. The Mg/Si ratio of the star is found to be 1.78, which is much greater than for Earth (about 1.2). With a system that has such an excess of Mg to Si ratio it is possible that the mineralogical make-up of planets around {\tau} Ceti could be significantly different from that of Earth, with possible oversaturation of MgO, resulting in an increase in the content of olivine and ferropericlase compared with Earth. The increase in MgO would have a drastic impact on the rheology of the mantles of the planets around {\tau} Ceti.Comment: 17 pages, 1 figure, supplemental table, Astrophysical Journa

Doppler imaging of the young late-type star LO Pegasi (BD +22 4409) in September 2003

A Doppler image of the ZAMS late-type rapidly rotating star LO Pegasi, based on spectra acquired between 12 and 15 September 2003, is presented. The Least Square Deconvolution technique is applied to enhance the signal-to-noise ratio of the mean rotational broadened line profiles extracted from the observed spectra. In the present application, a unbroadened spectrum is used as a reference, instead of a simple line list, to improve the deconvolution technique applied to extract the mean profiles. The reconstructed image is similar to those previously obtained from observations taken in 1993 and 1998, and shows that LO Peg photospheric activity is dominated by high-latitude spots with a non-uniform polar cap. The latter seems to be a persistent feature as it has been observed since 1993 with little modifications. Small spots, observed between ~ 10 and ~ 60 degrees of latitude, appears to be different with respect to those present in the 1993 and 1998 maps.Comment: 21 pages, 10 figures, accepted by Monthly Notices of the Royal Astronomical Societ

Sharing Default Information as a Borrower Discipline Device

Creditors often share information about their customers' credit record. Besides helping them to spot bad risks, this informational exchange acts as a disciplinary device. If creditors are known to exchange data about defaults, borrowers must consider that default on a current lender would disrupt their credit rating with all the other lenders. This raises their incentive to perform. But sharing more detailed information can reduce this disciplinary effect: when lenders only disclose past defaults, borrowers' incentives to perform may be greater than when lenders share all their information. In some instances, by "fine-tuning" the type and accuracy of the information shared, lenders can raise borrowers' incentives to their first-best level.Fiscal policy, national saving, contractionary fiscal expansions

Markov Chain Beam Randomization: a study of the impact of PLANCK beam measurement errors on cosmological parameter estimation

We introduce a new method to propagate uncertainties in the beam shapes used to measure the cosmic microwave background to cosmological parameters determined from those measurements. The method, which we call Markov Chain Beam Randomization, MCBR, randomly samples from a set of templates or functions that describe the beam uncertainties. The method is much faster than direct numerical integration over systematic `nuisance' parameters, and is not restricted to simple, idealized cases as is analytic marginalization. It does not assume the data are normally distributed, and does not require Gaussian priors on the specific systematic uncertainties. We show that MCBR properly accounts for and provides the marginalized errors of the parameters. The method can be generalized and used to propagate any systematic uncertainties for which a set of templates is available. We apply the method to the Planck satellite, and consider future experiments. Beam measurement errors should have a small effect on cosmological parameters as long as the beam fitting is performed after removal of 1/f noise.Comment: 17 pages, 23 figures, revised version with improved explanation of the MCBR and overall wording. Accepted for publication in Astronomy and Astrophysics (to appear in the Planck pre-launch special issue

A novel CMB polarization likelihood package for large angular scales built from combined WMAP and Planck LFI legacy maps

We present a CMB large-scale polarization dataset obtained by combining WMAP Ka, Q and V with Planck 70 GHz maps. We employ the legacy frequency maps released by the WMAP and Planck collaborations and perform our own Galactic foreground mitigation technique, which relies on Planck 353 GHz for polarized dust and on Planck 30 GHz and WMAP K for polarized synchrotron. We derive a single, optimally-noise-weighted, low-residual-foreground map and the accompanying noise covariance matrix. These are shown, through $\chi^2$ analysis, to be robust over an ample collection of Galactic masks. We use this dataset, along with the Planck legacy Commander temperature solution, to build a pixel-based low-resolution CMB likelihood package, whose robustness we test extensively with the aid of simulations, finding excellent consistency. Using this likelihood package alone, we constrain the optical depth to reionazation $\tau=0.069^{+0.011}_{-0.012}$ at $68\%$ C.L., on 54\% of the sky. Adding the Planck high-$\ell$ temperature and polarization legacy likelihood, the Planck lensing likelihood and BAO observations we find $\tau=0.0714_{-0.0096}^{+0.0087}$ in a full $\Lambda$CDM exploration. The latter bounds are slightly less constraining than those obtained employing \Planck\ HFI CMB data for large angle polarization, that only include EE correlations. Our bounds are based on a largely independent dataset that does include also TE correlations. They are generally well compatible with Planck HFI preferring slightly higher values of $\tau$. We make the low-resolution Planck and WMAP joint dataset publicly available along with the accompanying likelihood code.Comment: The WMAP+LFI likelihood module is available on \http://www.fe.infn.it/u/pagano/low_ell_datasets/wmap_lfi_legacy

What Makes Stock Exchanges Succeed? Evidence from Cross-Listing Decisions

Despite the increasing integration of capital markets, geography has not yet become irrelevant to finance. Between 1986 and 1997, European public companies have increasingly listed abroad, especially in the U.S. We relate the cross-listing decisions to the characteristics of the destination exchanges (and countries) relative to those of the home exchange (and country). European companies appear more likely to cross-list in more liquid and larger markets, and in markets where several companies from their industry are already cross-listed. They are also more likely to cross-list in countries with better investor protection, and more efficient courts and bureaucracy, but not with more stringent accounting standards.cross-listings, going public, initial public offerings, geography, stock market competition