19,744 research outputs found
Studying Diquark Structure of Heavy Baryons in Relativistic Heavy Ion Collisions
We propose the enhancement of yield in heavy ion collisions at
RHIC and LHC as a novel signal for the existence of diquarks in the strongly
coupled quark-gluon plasma produced in these collisions as well as in the
. Assuming that stable bound diquarks can exist in the quark-gluon
plasma, we argue that the yield of would be increased by two-body
collisions between diquarks and quarks, in addition to normal
three-body collisions among , and quarks. A quantitative study of
this effect based on the coalescence model shows that including the
contribution of diquarks to production indeed leads to a
substantial enhancement of the ratio in heavy ion collisions.Comment: Prepared for Chiral Symmetry in Hadron and Nuclear Physics
(Chiral07), Nov. 13-16, 2007, Osaka, Japa
Stabilizing the forming process in unipolar resistance switching using an improved compliance current limiter
The high reset current IR in unipolar resistance switching now poses major
obstacles to practical applications in memory devices. In particular, the first
IR-value after the forming process is so high that the capacitors sometimes do
not exhibit reliable unipolar resistance switching. We found that the
compliance current Icomp is a critical parameter for reducing IR-values. We
therefore introduced an improved, simple, easy to use Icomp-limiter that
stabilizes the forming process by drastically decreasing current overflow, in
order to precisely control the Icomp- and subsequent IR-values.Comment: 15 pages, 4 figure
Double-Well Potential : The WKB Approximation with Phase Loss and Anharmonicity Effect
We derive a general WKB energy splitting formula in a double-well potential
by incorporating both phase loss and anharmonicity effect in the usual WKB
approximation. A bare application of the phase loss approach to the usual WKB
method gives better results only for large separation between two potential
minima. In the range of substantial tunneling, however, the phase loss approach
with anharmonicity effect considered leads to a great improvement on the
accuracy of the WKB approximation.Comment: 14 pages, revtex, 1 figure, will appear at Phys. Rev.
The influence of position in overlap joints of Mg and Al alloys on microstructure and hardness of laser welds
Structure and properties of laser beam welding zone of dissimilar materials, AZ31 magnesium alloy and A5754 Aluminum alloy, are investigated. The microstructure and quality of the Mg/Al weld were studied by metallography, microhardness and optical microscopy. Differences in physical and mechanical properties of both materials, magnesium and aluminum, affect weldability and resistance of this combination, and lead to the formation of intermetallic compounds in the welded metal
Magnification Probability Distribution Functions of Standard Candles in a Clumpy Universe
Lensing effects on light rays from point light sources, such like Type Ia
supernovae, are simulated in a clumpy universe model. In our universe model, it
is assumed that all matter in the universe takes the form of randomly
distributed objects each of which has finite size and is transparent for light
rays. Monte-Carlo simulations are performed for several lens models, and we
compute probability distribution functions of magnification. In the case of the
lens models that have a smooth density profile or the same degree of density
concentration as the spherical NFW (Navarro-Frenk-White) lens model at the
center, the so-called gamma distributions fit well the magnification
probability distribution functions if the size of lenses is sufficiently larger
than the Einstein radius. In contrast, the gamma distributions do not fit the
magnification probability distribution functions in the case of the SIS
(Singular Isothermal Sphere) lens model. We find, by using the power law cusp
model, that the magnification probability distribution function is fitted well
using the gamma distribution only when the slope of the central density profile
is not very steep. These results suggest that we may obtain information about
the slope of the central density profiles of dark matter halo from the lensing
effect of Type Ia supernovae.Comment: 25 pages, 12 figures, PTP accepted versio
Social media use and impact during the holiday travel planning process
Through an empirical study among holiday travellers, residing in the Former Soviet Union Republics, this paper presents a comprehensive view of role and impact of social media on the whole holiday travel planning process: Before, during and after the trip, providing insights on usage levels, scope of use, level of influence and trust. Findings suggest that social media are predominantly used after holidays for experience sharing. It is also shown that there is a strong correlation between perceived level of influence from social media and changes made in holiday plans prior to final decisions. Moreover, it is revealed that user-generated content is perceived as more trustworthy when compared to official tourism websites, travel agents and mass media advertising
A computationally efficient inorganic atmospheric aerosol phase equilibrium model (UHAERO)
A variety of thermodynamic models have been developed to predict inorganic gas-aerosol equilibrium. To achieve computational efficiency a number of the models rely on a priori specification of the phases present in certain relative humidity regimes. Presented here is a new computational model, named UHAERO, that is both efficient and rigorously computes phase behavior without any a priori specification. The computational implementation is based on minimization of the Gibbs free energy using a primal-dual method, coupled to a Newton iteration. The mathematical details of the solution are given elsewhere. The model also computes deliquescence and crystallization behavior without any a priori specification of the relative humidities of deliquescence or crystallization. Detailed phase diagrams of the sulfate/nitrate/ammonium/water system are presented as a function of relative humidity at 298.15 K over the complete space of composition
A new inorganic atmospheric aerosol phase equilibrium model (UHAERO)
A variety of thermodynamic models have been developed to predict inorganic gas-aerosol equilibrium. To achieve computational efficiency a number of the models rely on a priori specification of the phases present in certain relative humidity regimes. Presented here is a new computational model, named UHAERO, that is both efficient and rigorously computes phase behavior without any a priori specification. The computational implementation is based on minimization of the Gibbs free energy using a primal-dual method, coupled to a Newton iteration. The mathematical details of the solution are given elsewhere. The model computes deliquescence behavior without any a priori specification of the relative humidities of deliquescence. Also included in the model is a formulation based on classical theory of nucleation kinetics that predicts crystallization behavior. Detailed phase diagrams of the sulfate/nitrate/ammonium/water system are presented as a function of relative humidity at 298.15 K over the complete space of composition
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