Deduction of the quantum unmbers of low-lying states of the (e+e+e-e-) system from symmetry consideration

The feature of the low-lying spectrum and a complete set of quantum numbers of the (e+e+e-e-) system have been deduced based on symmetry consideration. The existence of a low odd-parity L=1 excited state with the spins of the two electrons coupled to s1=1 and the two positrons coupled to s2=0 (or s1=0 and s2=1) and a low even-parity L=0 excited state with s1=s2=1 have been predicted. The discussion is generalized to 2-dimensional (e+e+e-e-) systems.Comment: 12 pages, 5 tables, no figure

A study of the effect of open biomass burning aerosol on rainfall event over Malaysia by using EOF analysis.

Significant biomass burning aerosols resulted from biomass burning activities from Sumatra and Kalimantan Island transported to Malaysia every year from August to October by the southeast monsoon. These transboundary haze changes the precipitation pattern by aerosol interaction with radiation and cloud which affects the solar radiation budget and cloud condensation nuclei properties. In this work, empirical orthogonal function (EOF) was used to assess the effect of biomass burning aerosol on rainfall pattern over Malaysia from both a spatial and a temporal perspective. Over Peninsular Malaysia, regional rainfall activities tend to be suppressed by concentrated biomass burning aerosols and produce another heavy rain over the downwind areas after 30-60 days (60 days) under highly (less) populated condition. Similar precipitation pattern has been indicated over Sarawak and Sabah where biomass burning aerosols suppress rainfall in the southwestern area while leads to a more intensified rainfall event in the northeast area with 30-60 days (60 days) interval under highly (less) populated condition

The Extent of Internet Auction Markets

Internet auctions attract numerous agents, but only a few become active bidders. A major difficulty in the structural analysis of internet auctions is that the number of potential bidders is unknown. Under the independent private value paradigm (IPVP)the valuations of the active bidders form a specific record sequence. This record sequence implies that if the number n of potential bidders is large, the number of active bidders is approximately 2 log n, explaining the relative inactivity. Empirical evidence for the 2 log n rule is provided. This evidence can also be interpreted as a weak test of the IPVP

Infrared activity of hydrogen molecules trapped in Si

The rovibrational-translational states of a hydrogen molecule moving in a cage site in Si, when subjected to an electrical field arising from its surroundings, are investigated. The wave functions are expressed in terms of basis functions consisting of the eigenfunctions of the molecule confined to move in the cavity and rovibrational states of the free molecule. The energy levels, intensities of infrared and Raman transitions, effects of uniaxial stress, and a neighboring oxygen defect are found and compared with existing experimental data

Phase stability, elastic properties and electronic structures of Mg–Y intermetallics from first-principles calculations

AbstractThe phase stability, elastic properties and electronic structures of three typical Mg–Y intermetallics including Mg24Y5, Mg2Y and MgY are systematically investigated using first-principles calculations based on density functional theory. The optimized structural parameters including lattice constants and atomic coordinates are in good agreement with experimental values. The calculated cohesive energies and formation enthalpies show that either phase stability or alloying ability of the three intermetallics is gradually enhanced with increasing Y content. The single-crystal elastic constants Cij of Mg–Y intermetallics are also calculated, and the bulk modulus B, shear modulus G, Young's modulus E, Poisson ratio v and anisotropy factor A of polycrystalline materials are derived. It is suggested that the resistances to volume and shear deformation as well as the stiffness of the three intermetallics are raised with increasing Y content. Besides, these intermetallics all exhibit ductile characteristics, and they are isotropic in compression but anisotropic to a certain degree in shear and stiffness. Comparatively, Mg24Y5 presents a relatively higher ductility, while MgY has a relatively stronger anisotropy in shear and stiffness. Further analysis of electronic structures indicates that the phase stability of Mg–Y intermetallics is closely related with their bonding electrons numbers below Fermi level. Namely, the more bonding electrons number below Fermi level corresponds to the higher structural stability of Mg–Y intermetallics

Analytical method of process capability for steel

The mechanical properties of steel are the most important factor in the safety of structures that must be stable and appropriate. In order to investigate whether the process capability of steel production meets the quality requirements or not, Sung et al. proposed a procedure to evaluate the production and quality control of steel manufacturing. This evaluation model uses statistics to judge the quality of steel objectively. However, there are various types of steel which can satisfy the engineering requirements of design and construction, but procedures are lacking with which to evaluate the multi-process capability of the whole steelwork. In this paper, the objective evaluation methods proposed by Sung and Vannman are modified appropriately and extended by using the principles of statistical inference. A procedure to evaluate the quality of the multi-process capability analysis method is proposed. This evaluation method not only completely evaluates the process capability and quality, but it also improves the production process and quality control capability, and so can reduce production loss

D-brane dynamics near compactified NS5-branes

We examine the dynamics of a $Dp$-brane in the background of $k$ coincident, parallel $NS$5-branes which have had one of their common transverse directions compactified. We find that for small energy, bound orbits can exist at sufficiently large distances where there will be no stringy effects. The orbits are dependent upon the energy density, angular momentum and electric field. The analysis breaks down at radial distances comparable with the compactification radius and we must resort to using a modified form of the harmonic function in this region.Comment: Latex, 20 pages, 6 figs, references adde

Thermal Partition Functions for S-branes

We calculate the thermal partition functions of open strings on the S-brane backgrounds (the bouncing or rolling tachyon backgrounds) both in the bosonic and superstring cases. According to hep-th/0302146, we consider the discretized temperatures compatible with the pure imaginary periodicity of tachyon profiles. The ``effective Hagedorn divergence'' is shown to appear no matter how low temperature is chosen (including zero-temperature). This feature is likely to be consistent with the large rate of open string pair production discussed in hep-th/0209090 and also emission of closed string massive modes hep-th/0303139. We also discuss the possibility to remove the divergence by considering the space-like linear dilaton backgrounds as in hep-th/0306132.Comment: 33 pages, no figure; v2 typos corrected, a reference adde

Discovery and Measurement of Sleptons, Binos, and Winos with a Z'

Extensions of the MSSM could significantly alter its phenomenology at the LHC. We study the case in which the MSSM is extended by an additional U(1) gauge symmetry, which is spontaneously broken at a few TeV. The production cross-section of sleptons is enhanced over that of the MSSM by the process $pp\to Z' \to \tilde{\ell} \tilde{\ell}^*$, so the discovery potential for sleptons is greatly increased. The flavor and charge information in the resulting decay, $\tilde{\ell} \to \ell + {LSP}$, provides a useful handle on the identity of the LSP. With the help of the additional kinematical constraint of an on-shell Z', we implement a novel method to measure all of the superpartner masses involved in this channel. For certain final states with two invisible particles, one can construct kinematic observables bounded above by parent particle masses. We demonstrate how output from one such observable, m_T2, can become input to a second, increasing the number of measurements one can make with a single decay chain. The method presented here represents a new class of observables which could have a much wider range of applicability.Comment: 20 pages, 15 figures; v2 references added and minor change