494 research outputs found
How Volatile is ENSO for Global Greenhouse Gas Emissions and the Global Economy?
This paper analyzes two indexes in order to capture the volatility inherent in El Niños Southern Oscillations (ENSO), develops the relationship between the strength of ENSO and greenhouse gas emissions, which increase as the economy grows, with carbon dioxide being the major greenhouse gas, and examines how these gases affect the frequency and strength of El Niño on the global economy. The empirical results show that both the ARMA(1,1)-GARCH(1,1) and ARMA(3,2)-GJR(1,1) models are suitable for modelling ENSO volatility accurately, and that 1998 is a turning point, which indicates that the ENSO strength has increased since 1998. Moreover, the increasing ENSO strength is due to the increase in greenhouse gas emissions. The ENSO strengths for Sea Surface Temperature (SST) are predicted for the year 2030 to increase from 29.62% to 81.5% if global CO2 emissions increase by 40% to 110%, respectively. This indicates that we will be faced with even stronger El Nino or La Nina effects in the future if global greenhouse gas emissions continue to increase unabated
Modelling the Effects of Oil Prices on Global Fertilizer Prices and Volatility
The main purpose of this paper is to evaluate the effect of crude oil price on global fertilizer prices in both the mean and volatility. The endogenous structural breakpoint unit root test, ARDL model, and alternative volatility models, including GARCH, EGARCH, and GJR models, are used to investigate the relationship between crude oil price and six global fertilizer prices. The empirical results from ARDL show that most fertilizer prices are significantly affected by the crude oil price while the volatility of global fertilizer prices and crude oil price from March to December 2008 are higher than in other periods
Modeling the Volatility in Global Fertilizer Prices
The main purpose of this paper is to estimate the volatility in global fertilizer prices. The endogenous structural breakpoint unit root test and alternative volatility models, including the generalized autoregressive conditional heteroskedasticity (GARCH) model, Exponential GARCH (EGARCH) model, and GJR model are estimated for six global fertilizer prices and the crude oil price. Weekly data for 2003-2008 for the seven price series are analysed. The empirical results suggest that the volatility of global fertilizer prices and crude oil price from March to December 2008 are higher than in other periods, and that the peak crude oil price caused greater volatility in the crude oil price and global fertilizer prices
Modeling the Effect of Oil Price on Global Fertilizer Prices
The main purpose of this paper is to evaluate the effect of crude oil price on global fertilizer prices in both the mean and volatility. The endogenous structural breakpoint unit root test, the autoregressive distributed lag (ARDL) model, and alternative volatility models, including the generalized autoregressive conditional heteroskedasticity (GARCH) model, Exponential GARCH (EGARCH) model, and GJR model, are used to investigate the relationship between crude oil price and six global fertilizer prices. Weekly data for 2003-2008 for the seven price series are analyzed. The empirical results from ARDL show that most fertilizer prices are significantly affected by the crude oil price, which explains why global fertilizer prices reached a peak in 2008. We also find that that the volatility of global fertilizer prices and crude oil price from March to December 2008 are higher than in other periods, and that the peak crude oil price caused greater volatility in the crude oil price and global fertilizer prices. As volatility invokes financial risk, the relationship between oil price and global fertilizer prices and their associated volatility is important for public policy relating to the development of optimal energy use, global agricultural production, and financial integration
From Tetraquark to Hexaquark: A Systematic Study of Heavy Exotics in the Large Limit
A systematic study of multiquark exotics with one or heavy quarks in
the large limit is presented. By binding a chiral soliton to a heavy
meson, either a normal -quark baryon or an exotic -quark baryon
is obtained. By replacing the heavy quark with heavy antiquarks, exotic
-quark and -quark mesons are obtained. When , they are
just the normal triquark baryon , the exotic pentaquark baryon , tetraquark di-meson and the hexaquark
di-baryon respectively. Their
stabilities and decays are also discussed. In particular, it is shown that the
``heavy to heavy'' semileptonic decays are described by the Isgur--Wise form
factors of the normal baryons.Comment: 14 pages in REVTeX, no Figure
Dissipative Dynamics of a Josephson Junction In the Bose-Gases
The dissipative dynamics of a Josephson junction in the Bose-gases is
considered within the framework of the model of a tunneling Hamiltonian. The
effective action which describes the dynamics of the phase difference across
the junction is derived using functional integration method. The dynamic
equation obtained for the phase difference across the junction is analyzed for
the finite temperatures in the low frequency limit involving the radiation
terms. The asymmetric case of the Bose-gases with the different order
parameters is calculated as well
An econometric analysis of SARS and Avian flu on international tourist arrivals to Asia
This paper compares the impacts of SARS and human deaths arising from Avian Flu on international tourist arrivals to Asia. The effects of SARS and human deaths from Avian Flu will be compared directly according to human deaths. The nature of the short run and long run relationship is examined empirically by estimating a static line fixed effect model and a difference transformation dynamic model, respectively. Empirical results from the static fixed effect and difference transformation dynamic models are consistent, and indicate that both the short run and long run SARS effect have a more significant impact on international tourist arrivals than does Avian Flu. In addition, the effects of deaths arising from both SARS and Avian Flu suggest that SARS is more important to international tourist arrivals than is Avian Flu. Thus, while Avian Flu is here to stay, its effect is currently not as significant as that of SARS
Soliton back-action evading measurement using spectral filtering
We report on a back-action evading (BAE) measurement of the photon number of
fiber optical solitons operating in the quantum regime. We employ a novel
detection scheme based on spectral filtering of colliding optical solitons. The
measurements of the BAE criteria demonstrate significant quantum state
preparation and transfer of the input signal to the signal and probe outputs
exiting the apparatus, displaying the quantum-nondemolition (QND) behavior of
the experiment.Comment: 5 pages, 5 figure
Superconductivity from correlated hopping
We consider a chain described by a next-nearest-neighbor hopping combined
with a nearest-neighbor spin flip. In two dimensions this three-body term
arises from a mapping of the three-band Hubbard model for CuO planes to a
generalized model and for large O-O hopping favors resonance-valence-bond
superconductivity of predominantly -wave symmetry. Solving the ground state
and low-energy excitations by analytical and numerical methods we find that the
chain is a Luther-Emery liquid with correlation exponent , where is the particle density.Comment: 10 pages, RevTeX 3.0 + 2 PostScript figs. Accepted for publication in
Phys.Rev.
Pairing Correlations in a Generalized Hubbard Model for the Cuprates
Using numerical diagonalization of a 4x4 cluster, we calculate on-site s,
extended s and d pairing correlation functions (PCF) in an effective
generalized Hubbard model for the cuprates, with nearest-neighbor correlated
hopping and next nearest-neighbor hopping t'. The vertex contributions (VC) to
the PCF are significantly enhanced, relative to the t-t'-U model. The behavior
of the PCF and their VC, and signatures of anomalous flux quantization,
indicate superconductivity in the d-wave channel for moderate doping and in the
s-wave channel for high doping and small U.Comment: 5 pages, 5 figure
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