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Papers by liu liu

Frontiers in Earth Science

Since there is no precedent for the use of slotted shield tunneling in the large section of high-... more Since there is no precedent for the use of slotted shield tunneling in the large section of high-speed railways in China, the relevant technological accumulation and systematic research achievements are few. Therefore, this paper provides theoretical support for loess tunnel construction decision-making through the study of slotted shields and is expected to promote the mechanization and even intelligent construction of a high-speed iron-loess tunnel. Taking the Luochuan tunnel of the Xiyan high-speed railway as the engineering background, this paper uses the numerical simulation software packages of ANSYS and FLAC3D to study the tunnel deformation (surface settlement, vault settlement, tunnel bottom uplift, and horizontal convergence) caused by the slotted shield construction in three different buried depths of 30, 40, and 50 m surrounding rock. The deformation law and mechanical characteristics of a cutter shield construction of large cross-section loess tunnels under the influenc...

Optoelectronic Materials and Devices IV, 2009

We introduce a compact, low-power electro-optical switch on silicon-on-insulator circuit through ... more We introduce a compact, low-power electro-optical switch on silicon-on-insulator circuit through heterogeneous integration. A III-V microdisk cavity with a diameter of 10µm is employed as the switching element. Switching of a 10Gbps optical signal is demonstrated by sweeping the bias between-1.1V-0.9V with 15dB extinction ratio and 1.2ns switching speed.

Journal of Modern Transportation, 2012

In order to obtain accurate characteristics of wireless channels in the viaduct area of China, a ... more In order to obtain accurate characteristics of wireless channels in the viaduct area of China, a channel measurement was taken in a railway viaduct scenario of the Zhengzhou-Xi'an passenger dedicated line with a bandwidth of 50 MHz at 2.35 GHz. The single-slope log-distance model is used to analyze the path-loss (PL), and the distribution of shadow fading (SF) is obtained by statistical methods, which shows that the normal distribution fits the samples well. Ricean K-factor is analyzed by the method of moments, and the variation of K-factor is given along the measured route. Small scale such as delay spread and Doppler behavior are parameterized. Based on empirical channel measurement, this paper provides parameters for the evaluation and simulation work on viaduct scenarios of high-speed railway.

2009 6th IEEE International Conference on Group IV Photonics, 2009

We demonstrate design, fabrication and measurement of silicon-on-insulator microring resonators s... more We demonstrate design, fabrication and measurement of silicon-on-insulator microring resonators suitable for ultra dense WDM applications with a channel spacing of 0.1nm. Considerations about applying it to practical use are also discussed.

Chinese medical journal, Jan 20, 2009

This study was to investigate the safety of two types of commercially available lumbar artificial... more This study was to investigate the safety of two types of commercially available lumbar artificial discs (CHARITE and PRODISC-L) during a magnetic resonance imaging (MRI) procedure in a 1.5-Tesla MR system, and to evaluate the size of metal artifacts on the MR image for different sequences. A 1.5-Tesla clinical MR imaging system was used. The degree of deflection of the endplates of two artificial discs was evaluated by an angle-measurement instrument at the portals of the MRI scanner. The heating effect of the radio frequency (RF) magnetic field was evaluated by using "worst-case" imaging sequences on a human cadaver implanted with an artificial lumbar disc at the L5/S1 intervertebral disc location. The temperatures of the tissue adjacent to the implant, and of the L4/L5 intervertebral disc (used as a control) were measured, respectively, using a digital probe thermometer before and after the MRI scan sequence. A rectangular water phantom was designed to evaluate the metal...

$Research paper thumbnail of Analysis of the polarization-dependent diffraction from a metallic grating by use of a three-dimensional combined vectorial method$

Journal of the Optical Society of America A, 2004

A three-dimensional combined vectorial method, which is based on the finite-difference time-domai... more A three-dimensional combined vectorial method, which is based on the finite-difference time-domain algorithm and vectorial diffraction formulation, is introduced to analyze the interaction of a realistic focused beam with a metallic grating in an optical storage system. The diffracted field patterns and the detected signals are calculated for gratings with different geometries, and the polarization-dependent characteristics are studied. The combined method can give accurately the detected signals and the field pattern at any desired position of the optical storage system.

A novel division technique, Code and Time Hybrid Division for downlink transmission has been brou... more A novel division technique, Code and Time Hybrid Division for downlink transmission has been brought up in this article. Together with appropriate power allocation and code partitioning, larger capacity under certain fairness criterion is obtained in CTHD than that in orthogonal division.

MedChemComm, 2011

Using the same procedure as described for Boc-Trp-Trp-OBzl from 517 mg (1.0 mmol) of Trp-Trp-OBzl... more Using the same procedure as described for Boc-Trp-Trp-OBzl from 517 mg (1.0 mmol) of Trp-Trp-OBzl and 193 mg (1.1 mmol) of Boc-Gly 414 mg (65%) of the title compound was obtained as as colorless powder. Mp 206-208 ºC, ESI/MS(m/e) 638

Journal of Medicinal Chemistry, 2010

A series of compounds were designed and synthesized as antagonists of cIAP-1/2 and XIAP based upo... more A series of compounds were designed and synthesized as antagonists of cIAP-1/2 and XIAP based upon our previously identified lead compound SM-122 (1). The most potent of these (7) binds to XIAP, cIAP-1 and cIAP-2 proteins with K i values of 36, <1 and <1.9 nM, respectively. Consistent with its potent binding affinities to IAPs, 7 effectively antagonizes XIAP in a cell-free caspase-9 functional assay, efficiently induces cIAP-1 degradation in cells at concentrations as low as 10 nM, and triggers activation of caspases and PARP cleavage in the MDA-MB-231 breast cancer cell line. Compound 7 potently inhibits cell growth in the MDA-MB-231 cancer cell line with an IC 50 value of 200 nM and is 9 times more potent than compound 1.

Journal of Medicinal Chemistry, 2013

We have designed, synthesized and evaluated a series of new compounds based upon our previously r... more We have designed, synthesized and evaluated a series of new compounds based upon our previously reported bivalent Smac mimetics. This led to the identification of compound 12 (SM-1200), which binds to XIAP, cIAP1 and cIAP2 with K i values of 0.5 nM, 3.7 nM and 5.4 nM, respectively, inhibits cell growth in the MDA-MB-231 breast cancer and SK-OV-3 ovarian cancer cell lines with IC 50 values of 11.0 nM and 28.2 nM, respectively. Compound 12 has a much improved pharmacokinetic profile over our previously reported bivalent Smac mimetics and is highly effective in induction of rapid and durable tumor regression in the MDA-MB-231 xenograft model. These data indicate that compound 12 is a promising Smac mimetic and warrants extensive evaluation as a potential candidate for clinical development.

Journal of Mammary Gland Biology and Neoplasia, 2012

Apoptosis resistance is a hallmark of human cancer. Research in the last two decades has identifi... more Apoptosis resistance is a hallmark of human cancer. Research in the last two decades has identified key regulators of apoptosis, including inhibitor of apoptosis proteins (IAPs). These critical apoptosis regulators have been targeted for the development of new cancer therapeutics. In this article, we will discuss three members of IAP proteins, namely XIAP, cIAP1 and cIAP2, as cancer therapeutic targets and the progress made in developing new cancer therapeutic agents to target these IAP proteins. Apoptosis and human cancer Apoptosis, or programmed cell-death, is a fundamental cellular process to remove damaged or unwanted cells in multiple cellular organisms. Improper regulation of apoptosis is therefore linked in many human diseases, including cancer, autoimmune diseases, inflammation and neurological diseases. 1-3 In fact, defective regulation of apoptosis is a hallmark of human cancer. 4 Basic apoptosis pathways Apoptosis is a tightly regulated process. Several major apoptosis pathways have been identified and characterized in the last two decades, although these pathways often have extensive cross-talks. The intrinsic and extrinsic apoptosis pathways are two of the best studied (Figure 1). 5 The intrinsic, or mitochondria, apoptotic pathway integrates a variety of cell stress signals and is initiated by permeabilization of the outer membrane of mitochondria and loss of mitochondrial potential. On the molecular level, the intrinsic pathway involves the translocation and oligomerization of Bax or Bak, members of the Bcl-2 family proteins, which forms a pore in the outer member of mitochondria and leads to the release of proapoptotic molecules such as cytochrome C. Upon its release from mitochondria into cytosol, cytochrome C, together with dATP, Apaf-1 and procaspase-9, forms the apoptosome, which processes the procaspase-9 zymogen into the active form of caspase-9. Caspase-9 then cleaves and activates caspase-3,-6 and-7, which leads to further processing of downstream cell-death substrates, and ultimately apoptosis. The extrinsic, or death-receptor, apoptotic pathway, is initiated by the binding of death ligands such as Fas/Apo-1, TNF-alpha, Apo2L/TRAIL, and Apo3L ligands to their cognate cell-surface receptors, FasR, TNFR1, DR4/DR5 and DR3, respectively. The binding of these Phone:

IEEE Photonics Technology Letters, 2011

We present a polarization diversity circuit built on the silicon-on-insulator (SOI) platform, whi... more We present a polarization diversity circuit built on the silicon-on-insulator (SOI) platform, which can be fabricated by a simple process. The polarization diversity is based on two identical air-clad asymmetrical directional couplers, which simultaneously play the roles of polarization splitter and rotator. A silicon polarization diversity circuit with a single microring resonator is fabricated on the SOI platform. Only 1-dB polarization-dependent loss is demonstrated. A significant improvement of the polarization dependence is obtained for 20-Gb/s nonreturn-to-zero differential phase-shift keying (NRZ-DPSK) demodulation using the polarization diversity circuit, compared to a single microring resonator without polarization diversity.

Electronics Letters, 2010

Robust high-order matched filter (RHMF), utilizing high-order statistics and considering the inhe... more Robust high-order matched filter (RHMF), utilizing high-order statistics and considering the inherent variability in target spectral signatures, has obtained better results than other classical detection methods through experiments. However, this algorithm fails to get a fast convergence result by using simple steepest decent. In this paper, we accelerate this algorithm-RHMF successfully by introducing quasi-Newton method and DFP corrector formula, which is a more effective optimization algorithm based on second derivation, into this algorithm. We experiment constrained energy minimization (CEM), adaptive coherence estimator (ACE), RHMF with the steepest descent, and RHMF with quasi-Newton method on real data. The experiment by using RHMF with quasi-Newton has better and faster result, indicating that it is more effective for hyperspectral target detection. We also give the proof of the convergence of this method.

Computational Optimization and Applications, 2009

Multi-objective evolutionary algorithms (MOEAs) have become an increasingly popular tool for desi... more Multi-objective evolutionary algorithms (MOEAs) have become an increasingly popular tool for design and optimization tasks in real-world applications. Most of the popular baseline algorithms are pivoted on the use of Pareto-ranking (that is empirically inefficient) to improve the convergence to the Pareto front of a multiobjective optimization problem. This paper proposes a new ε-dominance MOEA (EDMOEA) which adopts pair-comparison selection and steady-state replacement instead of the Pareto-ranking. The proposed algorithm is an elitist algorithm with a new preservation technique of population diversity based on the ε-dominance relation. It is demonstrated that superior results could be obtained by the EDMOEA compared with other algorithms: NSGA-II, SPEA2, IBEA, ε-MOEA, PESA and PESA-II on test problems. The EDMOEA is able to converge to the Pareto optimal set much faster especially on the ZDT test functions with a large number of decision variables.

Communications in Statistics - Simulation and Computation, 2013

Nonparametric control chart is useful when the underlying distribution is unknown, or is not like... more Nonparametric control chart is useful when the underlying distribution is unknown, or is not likely to be normal. In this paper, we provide a sequential rank-based nonparametric adaptive EWMA (NAE) control chart for detecting the persistent shift in the location parameter. This NAE chart is a self-starting scheme and thus can be used to monitor processes at the start-up stages rather than waiting for the accumulation of sufficiently large calibration samples. Moreover, we do not require any prior knowledge of the underlying distribution, and to pre-specify any tuning parameter either. A Markov chain model is suggested to calibrate the run-length distribution of NAE, which is shown to has approximate tail probability as a geometric distribution. A simulation study demonstrates that the proposed control chart not only performs robustly for different distributions, but also is efficient in detecting various magnitude of shifts. A real-data example from manufacturing show that it performs quite well in practical applications.

Cancer Research, 2011

Proceedings: AACR 102nd Annual Meeting 2011‐‐ Apr 2‐6, 2011; Orlando, FL Second mitochondria-deri... more Proceedings: AACR 102nd Annual Meeting 2011‐‐ Apr 2‐6, 2011; Orlando, FL Second mitochondria-derived activator of caspase (Smac) is a protein released from mitochondria in response to apoptotic stimuli which functions as an endogenous inhibitor of several members of inhibitor of apoptotic proteins (IAPs), including XIAP, cIAP-1 and cIAP-2. Smac interacts with IAPs by binding of its N-terminal AVPI tetrapeptide to one or more BIR domains in IAPs. We designed and synthesized a series of non-peptidic, cell-permeable, bivalent small-molecules which mimic the dimeric Smac protein for targeting IAPs (bivalent Smac mimetics) and performed extensive evaluations of these bivalent Smac mimetics for their interaction with IAP proteins and their activity and mechanism of function in cancer cells. Our studies show that these Smac mimetics bind to XIAP, cIAP-1 and cIAP-2 with low nano-molar affinities. They function as extremely potent XIAP antagonists by concurrently targeting both the BIR2 and BIR3 domains of XIAP and nullify its inhibition to both caspase-9 and caspase-3/-7 and potently and effectively induce rapid degradation of these two proteins in cancer cells. The most potent bivalent Smac mimetics inhibit cell growth with IC50 values at low nanomolar and effectively induce apoptosis in a subset of cancer cell lines through TNFα dependent mechanism. Furthermore, bivalent Smac mimetics can dramatically enhance the antitumor activity of TRAIL in both TRAIL-sensitive and -resistant cancer cell lines. The combination of one such bivalent Smac mimetic, SM-164 with TRAIL induces rapid tumor regression in vivo in a breast cancer xenograft model in which either agent is ineffective. Mechanistic studies demonstrate that while RIP1 plays a minimal role in TRAIL's activity as a single agent, it is required for the synergistic interaction between TRAIL and SM-164. XIAP and cIAP1 work in concert to attenuate the activity of TRAIL and SM-164 strongly sensitizes TRAIL by concurrently targeting XIAP and cIAP1. Taken together, our data suggest that bivalent Smac mimetics may have a great therapeutic potential for the treatment of human cancer by targeting multiple IAPs, either alone or in combination with TRAIL. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3254. doi:10.1158/1538-7445.AM2011-3254