Low-Latitude Coronal Holes at the Minimum of the 23rd Solar Cycle

Low and mid-latitude coronal holes (CHs) observed on the Sun during the current solar activity minimum (from September 21, 2006, Carrington rotation (CR) 2048, until June 26, 2009 (CR 2084)) were analyzed using {\it SOHO}/EIT and STEREO-A SECCHI EUVI data. From both the observations and Potential Field Source Surface (PFSS) modeling, we find that the area occupied by CHs inside a belt of $\pm 40^\circ$ around the solar equator is larger in the current 2007 solar minimum relative to the similar phase of the previous 1996 solar minimum. The enhanced CH area is related to a recurrent appearance of five persistent CHs, which survived during 7-27 solar rotations. Three of the CHs are of positive magnetic polarity and two are negative. The most long-lived CH was being formed during 2 days and existed for 27 rotations. This CH was associated with fast solar wind at 1 AU of approximately 620$\pm 40$ km s$^{-1}$. The 3D MHD modeling for this time period shows an open field structure above this CH. We conclude that the global magnetic field of the Sun possessed a multi-pole structure during this time period. Calculation of the harmonic power spectrum of the solar magnetic field demonstrates a greater prevalence of multi-pole components over the dipole component in the 2007 solar minimum compared to the 1996 solar minimum. The unusual large separation between the dipole and multi-pole components is due to the very low magnitude of the dipole component, which is three times lower than that in the previous 1996 solar minimum.Comment: 14 pages, 7 figure

Double charmonium production at B-factories within light cone formalism

This paper is devoted to the study of the processes e^+e^- \to J/\Psi \eta_c, J/\Psi \eta_c', \psi' \eta_c, \psi' \eta_c' within light cone formalism. It is shown that if one disregards the contribution of higher fock states, the twist-3 distribution amplitudes needed in the calculation can be unambiguously determined from the twist-2 distribution amplitudes and equations of motion. Using models of the twist-2 distribution amplitudes the cross sections of the processes under study have been calculated. The results of the calculation are in agreement with Belle and BaBar experiments. It is also shown that relativistic and radiative corrections to the cross sections play crucial role in the achievement of the agreement between the theory and experiments. The comparison of the results of this paper with the results obtained in other papers has been carried out. In particular, it is shown that the results of papers where relativistic and radiative corrections were calculated within NRQCD are overestimated by a factor of ~1.5.Comment: 14 pages, 1 figur

The role of structural embeddedness in an IT outsourcing network

The design of governance to safeguard against a vendor's opportunistic behaviour is one of the critical issues in information technology outsourcing (ITO) since this behaviour causes cost escalation and service debasement. The roles of structural embeddedness underlying network governance have been gaining its importance as complementary or substitutable governance in ITO. Our research attempts to reveal how structural embeddedness can affect the decision-makings of clients and vendors and their resulting outcomes in an ITO network and how these effects are moderated by various ITO network structures according to outsourced IT services. An agent-based simulation and game-theoretic approach are adopted to build a simulation model to describe ITO networks with various structures and ITO transactions between clients and vendors. Finally, the future research directions are discussed

Black hole as an Information Eraser

We discuss the identity of black hole entropy and show that the first law of black hole thermodynamics, in the case of a Schwarzschild black hole, can be derived from Landauer's principle by assuming that the black hole is one of the most efficient information erasers in systems of a given temperature. The term "most efficient" implies that minimal energy is required to erase a given amount of information. We calculate the discrete mass spectra and the entropy of a Schwarzschild black hole assuming that the black hole processes information in unit of bits. The black hole entropy acquires a sub-leading contribution proportional to the logarithm of its mass-squared in addition to the usual mass-squared term without an artificial cutoff. We also argue that the minimum of the black hole mass is $\sqrt{\log 2/(8\pi)}M_P$.Comment: 12 pages, 4 figures, minor change

QCD sum rules for the anti-charmed pentaquark

We present a QCD sum rule analysis for the anti-charmed pentaquark state with and without strangeness. While the sum rules for most of the currents are either non-convergent or dominated by the $DN$ continuum, the one for the non-strange pentaquark current composed of two diquarks and an antiquark, is convergent and has a structure consistent with a positive parity pentaquark state after subtracting out the $DN$ continuum contribution. Arguments are presented on the similarity between the result of the present analysis and that based on the constituent quark models, which predict a more stable pentaquark states when the antiquark is heavy.Comment: 19 pages, 8 figures, REVTex, revised version,new figures added and references update

Three-Species Diffusion-Limited Reaction with Continuous Density-Decay Exponents

We introduce a model of three-species two-particle diffusion-limited reactions A+B -> A or B, B+C -> B or C, and C+A -> C or A, with three persistence parameters (survival probabilities in reaction) of the hopping particle. We consider isotropic and anisotropic diffusion (hopping with a drift) in 1d. We find that the particle density decays as a power-law for certain choices of the persistence parameter values. In the anisotropic case, on one symmetric line in the parameter space, the decay exponent is monotonically varying between the values close to 1/3 and 1/2. On another, less symmetric line, the exponent is constant. For most parameter values, the density does not follow a power-law. We also calculated various characteristic exponents for the distance of nearest particles and domain structure. Our results support the recently proposed possibility that 1d diffusion-limited reactions with a drift do not fall within a limited number of distinct universality classes.Comment: 12 pages in plain LaTeX and four Postscript files with figure