Abstract:
This paper studies the problem of finding an effective subcarrier and power allocation strategy for downlink communication to multiple users in a MIMO-OFDM system with zero-forcing beamforming. The problem of minimizing total power consumption with constraint on transmission rate for users is formulated. The problem of joint allocation is divided into two stages. In the first stage, the number of subcarriers that each user will get is determined based on the users’ average signal-to-noise ratio. In the second stage, it finds the best assignment of subcarriers to users. The optimal method is a complex combinatorial problem which can only be assuredly solved through an Exhaustive Search (ES). Since the ES method has high computational com-plexity, the normalized user selection algorithm and the simplified-normalized user selection algorithm are proposed to reduce the computational complexity. Simulation results show that the proposed low complexity algorithms offer better performance compared with an existing algorithm.

Abstract:
Scalar induced top decays may drastically suppress $B(t\to \ell\nu + jet)$ and still hide the top below $M_W$. The $p\bar p$ collider experiments should enlarge the scope and study the $m_t - B(t\to\ell\nu j)$ plane. Specific model signatures such as $t\to ch^0\to cb\bar b$ (multiple high $p_T$ $b$-jets) and $t\to bH^+\to bc\bar s$, $b\tau^+\nu$ (with $B(t\to b\tau\nu) \ \raisebox{-.5ex}{\rlap{$\sim$}} \raisebox{.4ex}{$<$}\ 1/3$) should be explored. Without ruling out these possibilities, isolated lepton signals in the future might actually be due to the 4th generation $t^\prime$ or $b^\prime$ quark, while top quark and toponium physics could still turn up at LEP-II.

Abstract:
The vector glueball $O$, made of 3 valence gluons, is expected to be ``clean": it mixes less with quarkonia, but mediates OZI violations. The recent $0^{++} $ glueball candidate and the persistence of the $J/\psi, \psi' \to \rho\pi$ puzzle suggest $m_O\simeq m_{J/\psi}$, with mixing angle $\sim 2^\circ - 4^\circ$, hence $\Gamma(O\to \rho\pi$, $K^+K^-$, $e^+e^-) \sim$ MeV, few keV, few eV. Lower and upper bounds on $\Gamma_O$ can be argued from $e^+e^- \to \rho\pi$ energy scan data and the condition $B(O\to \rho\pi) > B(J/\psi\to \rho\pi)$. $O$ dominance may explain the ``large" OZI violation in $^1S_0(\bar pp)\to \phi\gamma$ vs. $\omega\gamma$.

Abstract:
The highlights and conflicts at the B Factories are briefly reviewed. $CP$ violation was established in 2001 in $B^0 \to J/\psi K_S$ and related modes, which has now become a precision measurement of CP violation in $B^0$-$\bar B^0$ mixing. However, the situation for the $B^0 \to \pi^+\pi^-$ and charmless $b\to s$ modes, which probe also CP violation in the {\it decay} amplitude, are not quite settled yet. They could be hinting at presence of both strong (CP conserving) and new physics (CP violating) phases. We critically assess the developments and discuss some related discrepancies and highlights, such as observation of direct CP violation, and make a projection towards the next few years.

Abstract:
To improve spectrum efficiency (SE), the adaptive modulation and coding (AMC) and automatic repeat request (ARQ) scheme have been combined for MIMO systems. In this paper, we add variable power subject to power constraint in each AMC mode. We use KKT optimization algorithm to get the optimal transmit power and AMC mode boundaries. The numerical results show that the average SE is increased by about 0.5 bps/Hz for 2 × 2 MIMO systems with Nakagami fading with parameter m = 2 when SNR is around 15 dB and the ARQ retransmission is twice.

Abstract:
This paper aims to investigate whether banks exploit their information
advantage over bank-dependent borrowers, analyzing the impact of capital level
on banking credit risk-taking under syndication loans. By using a unique data
composed of 4828 syndicated loan of publicity banks facilities from the U.S.
for the period 1987-2010, we propose theoretical issues of the impact and effectiveness
of banks’ credit risk-taking from the perspectives of borrowers’ bank
dependent. The results show that there is positive correlation between the ratios
of bank’s capital over its total assets and banks’ credit risk-taking. It
implies that banks with lower capital level charge higher lending spread for
borrowers with fewer cash flows; hence the banks would bear a lower probability
of default.

Abstract:
We investigate the $R_b$--$R_c$ problem, starting from the more diffcult $R_c$. Introducing an isosinglet charge 2/3 quark $Q$ moves both $R_c$ and $R_b$ in the right direction. If one allows for large $c$-$Q$ {\it and} $t$-$Q$ mixings, then $R_c$ could be reduced because of singlet content of charm quark, while $R_b$ gets enhanced by a light effective top quark mass in the loop. The heavy quark observed at CDF would be dominantly a singlet quark, while the top quark is lighter than $M_W$. It is necessary to introduce a second Higgs doublet, where $H^+$ is heavy while at least one exotic neutral Higgs boson is very light. $H^+$--$h^0$ splitting accounts for $\delta\rho$, while light $h^0$ induce fast $t\to c + h^0$ decay and hides the actual top quark at the Tevatron. The scenario can be immediately tested at LEP II via search for light top production (and toponium!). At Tevatron, one should search for exotic decay modes such as $Q\to Z + X$ or $Q\to H + X$, or measure the BR for the standard $bW$ mode. Light top search should also be renewed.

Abstract:
We discuss the possibility and likelihood that one may observe {\it like sign} top quark pair production at the Linear Collider. In general two Higgs models, flavor changing couplings involving top quark could be quite sizable. Exotic neutral Higgs bosons may decay dominantly via $t\bar c$ or $\bar tc$ channels. At the linear collider, $e^+e^- \to h^0A^0$ or $H^0A^0$ production processes could lead to $b\bar bt\bar c$, $W^+W^-t\bar c$ or $tt\bar c\bar c$ (or $\bar t\bar tcc$) final states. These would mimic $T$-$\bar T$ mixing effect, except that $T$ mesons do not even form.