Bottom Quark Cross Sections at Collider and Fixed-Target Energies at the SSC and LHC

Calculations of inclusive cross sections for the production of bottom quarks in proton-proton collisions are presented as a function of energy, transverse momentum, and Feynman $x_F$ for values of $\sqrt{s}$ from $100~$GeV to $40~$TeV. In addition, we provide simple parametrizations of our theoretical results that should facilitate estimates of rates, acceptances, and efficiencies of proposed new detectors.Comment: 6 pages plus 11 topdraw figures appended as ps-files(uuencoded), Latex, ANL-HEP-CP-93-63 & CERN-TH.6987/9

Proton rich nuclei at and beyond the proton drip line in the Relativistic Mean Field theory

Ground state properties of proton-rich odd-$Z$ nuclei in the region $55\le Z \le 73$ are studied in the relativistic mean field (RMF) theory. The RMF equations are solved by using the expansion method in the Harmonic-Oscillator basis. In the particle-particle channel, we use the state-dependent BCS method with a zero-range $\delta$-force, which has been proved to be effective even for neutron-rich nuclei. All the ground state properties, including the one-proton separation energies, the ground state deformations, the last occupied proton orbits and the locations of proton drip line, are calculated. Good agreement with both the available experimental data and the predictions of the RHB method are obtained.Comment: the version to appear in Progress of Theoretical Physics, more discussions adde

Masses, Deformations and Charge Radii--Nuclear Ground-State Properties in the Relativistic Mean Field Model

We perform a systematic study of the ground-state properties of all the nuclei from the proton drip line to the neutron drip line throughout the periodic table employing the relativistic mean field model. The TMA parameter set is used for the mean-field Lagrangian density, and a state-dependent BCS method is adopted to describe the pairing correlation. The ground-state properties of a total of 6969 nuclei with $Z,N\ge 8$ and $Z\le 100$ from the proton drip line to the neutron drip line, including the binding energies, the separation energies, the deformations, and the rms charge radii, are calculated and compared with existing experimental data and those of the FRDM and HFB-2 mass formulae. This study provides the first complete picture of the current status of the descriptions of nuclear ground-state properties in the relativistic mean field model. The deviations from existing experimental data indicate either that new degrees of freedom are needed, such as triaxial deformations, or that serious effort is needed to improve the current formulation of the relativistic mean field model.Comment: 16 pages, 5 figures, to appear in Progress of Theoretical Physic

A systematic study of neutron magic nuclei with N = 8, 20, 28, 50, 82, and 126 in the relativistic mean field theory

We perform a systematic study of all the traditional neutron magic nuclei with $N$ = 8, 20, 28, 50, 82, and 126, from the neutron drip line to the proton drip line. We adopt the deformed relativistic mean field (RMF) theory as our framework and treat pairing correlations by a simple BCS method with a zero-range $\delta$-force. Remarkable agreement with the available experimental data is obtained for the binding energies, the two- and one-proton separation energies, and the nuclear charge radii. The calculated nuclear deformations are compared with the available experimental data and the predictions of the FRDM mass formula and the HFBCS-1 mass formula. We discuss, in particular, the appearance of sub-shell magic nuclei by observing irregular behavior in the two- and one-proton separation energies.Comment: the version to appear in Journal of Physics G; more references adde

Silencing E3 Ubiqutin ligase ITCH as a potential therapy to enhance chemotherapy efficacy in p53 mutant neuroblastoma cells

P53 mutations are responsible for drug-resistance of tumour cells which impacts on the efficacy of treatment. Alternative tumour suppressor pathways need to be explored to treat p53- deficient tumours. The E3 ubiquitin ligase, ITCH, negatively regulates the tumour suppressor protein TP73, providing a therapeutic target to enhance the sensitivity of the tumour cells to the treatment. In the present study, two p53-mutant neuroblastoma cell lines were used as in vitro models. Using immunostaining, western blot and qPCR methods, we firstly identified that ITCH was expressed on p53-mutant neuroblastoma cell lines. Transfection of these cell lines with ITCH siRNA could effectively silence the ITCH expression, and result in the stabilization of TP73 protein, which mediated the apoptosis of the neuroblastoma cells upon irradiation treatment. Finally, in vivo delivery of the ITCH siRNA using nanoparticles to the neuroblastoma xenograft mouse model showed around 15–20% ITCH silencing 48 hours after transfection. Our data suggest that ITCH could be silenced both in vitro and in vivo using nanoparticles, and silencing of ITCH sensitizes the tumour cells to irradiation treatment. This strategy could be further explored to combine the chemotherapy/radiotherapy treatment to enhance the therapeutic effects on p53-deficient neuroblastoma

Channel Parameters Estimation Algorithm Based on The Characteristic Function under Impulse Noise Environment

Under communication environments, such as wireless sensor networks, the noise observed usually exhibits impulsive as well as Gaussian characteristics. In the initialization of channel iterative decoder, such as low density parity check codes, it is required in advance to estimate the channel parameters to obtain the prior information from the received signals. In this paper, a blind channel parameters estimator under impulsive noise environment is proposed, which is based on the empirical characteristic function in MPSK/MQAM higher-order modulation system. Simulation results show that for various MPSK/MQAM modulations, the estimator can obtain a more accurate unbiased estimation even though we do not know which kind of higher-order modulation is used

Quantitative test of a quantum theory for the resistive transition in a superconducting single-walled carbon nanotube bundle

The phenomenon of superconductivity depends on the coherence of the phase of the superconducting order parameter. The resistive transition in quasi-one-dimensional (quasi-1D) superconductors is broad because of a large phase fluctuation. We show that the resistive transition of a superconducting single-walled carbon nanotube bundle is in quantitative agreement with the Langer-Ambegaokar-McCumber-Halperin (LAMH) theory. We also demonstrate that the resistive transition below T^*_c = 0.89T_c0 is simply proportional to exp [-(3\beta T^*_c/T)(1-T/T^*_c)^3/2], where the barrier height has the same form as that predicted by the LAMH theory and T_c0 is the mean field superconducting transition temperature.Comment: 4 pages, 3 figure