4,089 research outputs found
Elliptic Flow from Non-equilibrium Initial Condition with a Saturation Scale
A current goal of relativistic heavy ion collisions experiments is the search
for a Color Glass Condensate as the limiting state of QCD matter at very high
density. In viscous hydrodynamics simulations, a standard Glauber initial
condition leads to estimate , while a Color Glass
Condensate modeling leads to at least a factor of 2 larger . Within a
kinetic theory approach based on a relativistic Boltzmann-like transport
simulation, we point out that the out-of-equilibrium initial distribution
proper of a Color Glass Condensate reduces the efficiency in building-up the
elliptic flow. Our main result at RHIC energy is that the available data on
are in agreement with a also for Color Glass
Condensate initial conditions, opening the possibility to describe
self-consistently also higher order flow, otherwise significantly
underestimated, and to pursue further the search for signatures of the Color
Glass Condensate.Comment: 6 pages, 4 figures. // Title changed, some discussion added, main
conclusions unchanged. Version accepted for publication on Phys. Lett.
Italy
Il volume \ue8 uno studio comparativo degli ordinamenti giuridici dei 27 Stati membri dell'Unione europea. Il contributo di cui il sottoscritto risulta co-autore insieme a Ruggieri F. espone in inglese, in un formato comune, i tratti essenziali della procedura penale italiana
Option implied trees and implied moments
Implied trees are simple non-parametric discretizations of one- or two-dimension diffusions, aimed at introducing non-constant volatility in an option pricing model. The aim of the paper is twofold. First we investigate the ability of different option implied trees in pricing European options. Second, we compare the implied moments obtained with the use of option implied trees with the risk–neutral moments obtained with the use of Bakshi et al. (2003) formula and with realised physical moments. The comparison is pursued in the Italian market by analysing a data set which covers the years 2005-2009 and span both a relatively tranquil and a turmoil period. Keywords
Porting Decision Tree Algorithms to Multicore using FastFlow
The whole computer hardware industry embraced multicores. For these machines,
the extreme optimisation of sequential algorithms is no longer sufficient to
squeeze the real machine power, which can be only exploited via thread-level
parallelism. Decision tree algorithms exhibit natural concurrency that makes
them suitable to be parallelised. This paper presents an approach for
easy-yet-efficient porting of an implementation of the C4.5 algorithm on
multicores. The parallel porting requires minimal changes to the original
sequential code, and it is able to exploit up to 7X speedup on an Intel
dual-quad core machine.Comment: 18 pages + cove
On the ground state of gapless two flavor color superconductors
This paper is devoted to the study of some aspects of the instability of two
flavor color superconductive quark matter. We find that, beside color
condensates, the Goldstone boson related to the breaking of suffers of
a velocity instability. We relate this wrong sign problem, which implies the
existence of a Goldstone current in the ground state or of gluonic
condensation, to the negative squared Meissner mass of the gluon in
the g2SC phase. Moreover we investigate the Meissner masses of the gluons and
the squared velocity of the Goldstone in the multiple plane wave LOFF states,
arguing that in such phases both the chromo-magnetic instability and the
velocity instability are most probably removed. We also do not expect Higgs
instability in such multiple plane wave LOFF. The true vacuum of gapless two
flavor superconductors is thus expected to be a multiple plane wave LOFF state.Comment: 16 pages, RevTe3X4 styl
GREEN LOANS EXPERIENCES AS INVESTMENT MULTIPLIER SCHEMES
In recent years Italian national and regional governments have been active in promoting energy efficiency and renewable energies. The most effective measures are focused on the residential sector: feed-in tariffs for photovoltaic systems (higher tariffs for building integrated small plants), 55% tax credits for energy efficiency investments (windows or boilers substitutions, walls and roof insulations or even complete building refurbishments).
Recent surveys show that in some cases the customers are informed but cannot afford to pay for the needed investments and they prefer not to ask for loans, paying interests. In this situation the final customer may decide to opt for low quality refurbishments, not necessarily affecting the building energy consumption.
For these reasons there can still be some room left for some local supporting initiatives. In the Province of Milan the Mutuo A-profitto provided green loans with no interest to the consumers to all those who want to perform an energy efficient refurbishment of their house:
local banks provided the third party financing
interest were paid half by the bank itself and half by the province administration
the project designer or the installer had to declare the expected energy savings
In this way the customer obtained an interest-free loan up to 7 years: since the amount of the instalment could not exceed the amount of the expected economic savings, even the annual cash flow will be positive. Eligible measures include: glaze substitutions, walls and roof insulation, heating systems, solar water heater, heat pumps.
Since 2007, the Milanese Province administration has provided 1,35 million Euro funding, which mobilized 16\ua0million Euro of total investments. The Piedmont Region has recently introduced a similar scheme addressed to households and companies.
The paper provides an in depth description of the schemes adopted in Milan, an evaluation of the results and a comparison with the Piedmonts\u2019 experience and the "\ue9co-pr\ueat \ue0 taux z\ue9ro" (zero interest green loans) recently introduced in France by the Minist\ue8re du D\ue9veloppement Durable
Forecasting and pricing powers of option-implied tree models: Tranquil and volatile market conditions
The aims of this paper are twofold. First, to investigate the accuracy of different option-implied trees in pricing European options in order to assess the power of implied trees in replicating the market information. Second, to compare deterministic volatility implied trees and stochastic implied volatility models (Bakshi et al. (2003)) in assessing the forecasting power of implied moments on subsequently realised moments, and ascertaining the existence, magnitude and sign of variance, skewness, and kurtosis risk-premia. The analysis is carried out using the Italian daily market data covering the period 2005-2014. This enables us to contrast the pricing performance of implied trees and to assess the magnitude and sign of risk premia in both a tranquil and a turmoil period. The findings are as follows. First, the pricing performance of the Enhanced Derman and Kani (EDK, Moriggia et al. 2009) model is superior to that of the Rubinstein (1994) model. This superiority is stronger especially in the high volatility period due to a better estimation of the left tail of the distribution describing bad market conditions. Second, the Bakshi et al. (2003) formula is the most accurate for forecasting skewness and kurtosis, while for variance it yields upwardly biased forecasts. All models agree on the signs of the risk premia: negative for variance and kurtosis, and positive for skewness, but differ in magnitude. Overall, the results suggest that selling (buying) variance and kurtosis (skewness) is profitable in both high and low volatility periods
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