Comparison of the Geometrical Characters Inside Quark- and Gluon-jet Produced by Different Flavor Quarks

The characters of the angular distributions of quark jets and gluon jets with different flavors are carefully studied after introducing the cone angle of jets. The quark jets and gluon jets are identified from the 3-jet events which are produced by Monte Carlo simulation Jetset7.4 in e+e- collisions at $\sqrt s$=91.2GeV. It turns out that the ranges of angular distributions of gluon jets are obviously wider than that of quark jets at the same energies. The average cone angles of gluon jets are much larger than that of quark jets. As the multiplicity or the transverse momentum increases, the cone-angle distribution without momentum weight of both the quark jet and gluon jet all increases, i.e the positive linear correlation are present, but the cone-angle distribution with momentum weight decreases at first, then increases when n > 4 or p_t > 2 GeV. The characters of cone angular distributions of gluon jets produced by quarks with different flavors are the same, while there are obvious differences for that of the quark jets with different flavors.Comment: 13 pages, 6 figures, to be published on the International Journal of Modern Physics

ECONOMIC EFFECTS OF U.S. DAIRY PROGRAMS

Based on econometric analysis, this article estimates effects of terminating the milk order system and milk price support, singly and together, over the period 1966-90. Since 1980, milk orders have raised the national blend price by 1-2%; price support has raised the blend price to well above the market clearing price, by over 21% in 1983. Short- and long-run benefits and costs are estimated for various policy options under 1990 conditions.Agricultural and Food Policy,

Endogenous Matching and Contractual Choice between Agricultural Processors and Farmers in China

Contracts are widely used by agricultural processors for purchasing inputs not only in developed countries but also in developing countries such as China. The total number of formal, written contracts between farmers and food processors is increasing rapidly in China, and the formal contracts that exist are becoming more complex. Contractual design in China is evolving from simple price-quantity contracts toward more complicated arrangements known as cooperation contracts or joint-stock cooperation contracts, designed to share risk and mitigate opportunistic behaviors by the contracting parties. Due to small farm sizes, the contracted amount in the typical contract in China is very small compared with Western countries, and each processor usually has a large number of contracted farmers. This paper uses data from a 2003 survey of food processing firms by the Chinese Ministry of Agriculture to analyze the determinants of contractual choices between these firms and farmers and the number of farmers that each firm contracts with. An important issue identified in the literature in analyzing the determinants of contractual choices is endogenous matching between parties to a contract and the effects of this endogenous matching on contract choice. We find strong evidence to support endogenous matching. In particular, our results indicate that firms which contract with a larger number of farms are more likely to use cooperation contracts than relational contracts.China, contractual design, endogenous matching, farms, food processing, Agribusiness, Industrial Organization, Q13, L14,

NMR evidence of strong-correlated superconductivity in LiFeAs: tuning toward an SDW ordering

In this letter, we reported the results of NMR study on LiFeAs single crystals. We find a strong evidence of the low temperature spin fluctuations; by changing sample preparation conditions, the system can be tuned toward an spin-density-wave (SDW) quantum-critical point. The detection of an interstitial Li(2) ion, possibly locating in the tetrahedral hole, suggests that the off-stoichiometry and/or lattice defect can probably account for the absence of the SDW ordering in LiFeAs. These facts show that LiFeAs is a strongly correlated system and the superconductivity is likely originated from the SDW fluctuations.Comment: 5 pages, s figure

Spin-Orbit Coupling and Tunneling Current in a Parabolic Quantum Dot

We propose a novel approach to explore the properties of a quantum dot in the presence of the spin-orbit interaction and in a tilted magnetic field. The spin-orbit coupling within the quantum dot manifest itself as anti-crossing of the energy levels when the tilt angle is varied. The anti-crossing gap has a non-monotonic dependence on the magnitude of the magnetic field and exhibits a peak at some finite values of the magnetic field. From the dependence of the tunneling current through the quantum dot on the bias voltage and the tilt angle, the anti-crossing gap and most importantly the spin-orbit strength can be uniquely determined

Mining frequent trajectory patterns from GPS tracks

As recent advances and wide usage of mobile devices with positioning capabilities, trajectory database that captures the historical movements of populations of moving objects becomes important. Given such a database that contains many taxi trajectories, we study a new problem of discovering frequent sequential patterns. The proposed method comprises two phases. First, we cluster the stay points of taxis to get collocation patterns for passengers. Then, for each pattern instance, we use an efficient graph-based searching algorithm to mine the frequent trajectory patterns, which utilizes the adjacency property to reduce the search space. The performance evaluation demonstrates that our method outperforms the Apriori-based and PrefixSpan-based methods. ©2010 IEEE.published_or_final_versionThe 2010 International Conference on Computational Intelligence and Software Engineering (CiSE 2010), Wuhan, China, 10-12 December 2010. In Proceedings of CiSE, 2010, p. 1-