New Candidates for Topological Insulators : Pb-based chalcogenide series

Here, we theoretically predict that the series of Pb-based layered chalcogenides, Pb$_n$Bi$_2$Se$_{n+3}$ and Pb$_n$Sb$_2$Te$_{n+3}$, are possible new candidates for topological insulators. As $n$ increases, the phase transition from a topological insulator to a band insulator is found to occur between $n=2$ and 3 for both series. Significantly, among the new topological insulators, we found a bulk band gap of 0.40eV in PbBi$_2$Se$_4$ which is one of the largest gap topological insulators, and that Pb$_2$Sb$_2$Te$_5$ is located in the immediate vicinity of the topological phase boundary, making its topological phase easily tunable by changing external parameters such as lattice constants. Due to the three-dimensional Dirac cone at the phase boundary, massless Dirac fermions also may be easily accessible in Pb$_2$Sb$_2$Te$_5$

Valuation of the Risk of SARS in Taiwan

Two surveys conducted in Taiwan during the spring 2003 SARS epidemic reveal a high degree of concern about the threat posed by SARS to Taiwan and to residents, although respondents believe they are knowledgeable about the risk of SARS and that it is susceptible to individual control. WTP to reduce the risk of infection and death from SARS is elicited using contingent valuation methods. Estimated WTP is high, implying values per statistical life of US$3 to 12 million. While consistent with estimates for high-income countries, these values are substantially larger than previous estimates for Taiwan and may be attributable to the high degree of concern about SARS at the time the data were collected.

Experimental observation of hidden Berry curvature in inversion-symmetric bulk 2H-WSe2

We investigate the hidden Berry curvature in bulk 2H-WSe2 by utilizing the surface sensitivity of angle resolved photoemission (ARPES). The symmetry in the electronic structure of transition metal dichalcogenides is used to uniquely determine the local orbital angular momentum (OAM) contribution to the circular dichroism (CD) in ARPES. The extracted CD signals for the K and K' valleys are almost identical but their signs, which should be determined by the valley index, are opposite. In addition, the sign is found to be the same for the two spin-split bands, indicating that it is independent of spin state. These observed CD behaviors are what are expected from Berry curvature of a monolayer of WSe2. In order to see if CD-ARPES is indeed representative of hidden Berry curvature within a layer, we use tight binding analysis as well as density functional calculation to calculate the Berry curvature and local OAM of a monolayer WSe2. We find that measured CD-ARPES is approximately proportional to the calculated Berry curvature as well as local OAM, further supporting our interpretation.Comment: 6 pages, 3 figure

Integrated Analysis of Interferometric SAR, Satellite Altimetry and Hydraulic Modeling to Quantify Louisiana Wetland Dynamics

Wetland loss in Louisiana has been accelerating due primarily to anthropogenic and nature processes, and is being advocated as a problem with national importance. Accurate measurement or modeling of wetland-wide water level changes, its varying extent, its storage and discharge changes resulting in part from sediment loads, erosion and subsidence are fundamental to assessment of hurricane-induced flood hazards and wetland ecology. Here, we use innovative method to integrate interferometric SAR (InSAR) and satellite radar altimetry for measuring absolute or geocentric water level changes and applied the methodology to remote areas of swamp forest in coastal Louisiana. Coherence analysis of InSAR pairs suggested that the HH polarization is preferred for this type of observation, and polarimetric analysis can help to identi:fy double-bonnce backscattering areas in the wetland. Envisat radar altimeter-measured 18- Hz (along-track sampling of 417 m) water level data processed with regional stackfile method have been used to provide vertical references for water bodies separated by levees. The high-resolution (approx.40 m) relative water changes measured from ALOS PALSAR L-band and Radarsat-l C-band InSAR are then integrated with Envisat radar altimetry to obtain absolute water level. The resulting water level time series were validated with in situ gauge observations within the swamp forest. Furthermore, we compare our water elevation changes with 2D flood modeling from LISFLOOD hydrodynamic model. Our study demonstrates that this new technique allows retrospective reconstruction and concurrent monitoring of water conditions and flow dynamics in wetlands, especially those lacking gauge networks

An Open-Label, Multicenter, Phase I, Dose Escalation Study with Phase II Expansion Cohort to Determine the Safety, Pharmacokinetics, and Preliminary Antitumor Activity of Intravenous TKM-080301 in Subjects with Advanced Hepatocellular Carcinoma.

Lessons learnedTKM-080301 showed a favorable toxicity profile at the studied dose.TKM-080301 targeting PLK1 through small interfering RNA mechanism did not demonstrate improved overall survival in patients with advanced hepatocellular carcinoma compared with historical control. Preliminary antitumor activity as shown in this early-phase study does not support further evaluation as a single agent.BackgroundPolo-like kinase 1 (PLK1) is overexpressed in hepatocellular carcinoma (HCC). Knockdown of PLK1 expression by PLK1 small interfering RNA (siRNA) in an HCC cell line showed reduced expression in RNA-induced silencing complex and a reduction in cell proliferation.MethodsA 3 + 3 dose escalation plus expansion cohort at the maximum tolerated dose (MTD) was implemented. Patients with HCC, Eastern Cooperative Oncology Group (ECOG) performance status ≤2, and Child-Pugh score A received TKM-080301 as an intravenous infusion once every week for 3 consecutive weeks, repeated every 28 days.ResultsThe study enrolled 43 patients. The starting dose of TKM-080301 was 0.3 mg/kg, and MTD was declared at 0.75 mg/kg. Following the development of grade 4 thrombocytopenia in two subjects on the expansion cohort, the MTD was redefined at 0.6 mg/kg. Four patients did not have any evaluable postbaseline scan. Of the other 39 subjects who had received at least 0.3 mg/kg, 18 subjects (46.2%) had stable disease (SD) by independent RECIST 1.1 criteria. By Choi criteria, eight subjects (23.1%) had a partial response (PR). For 37 assessable subjects, with 2 subjects censored, median progression-free survival (PFS) was 2.04 months. Median survival for the whole study population was 7.5 months.ConclusionTKM-080301 was generally well tolerated. In this early-phase study, antitumor effect for TKM 080301 was limited. Further evaluation as a single agent in large randomized trials is not warranted

Cell Deformation by Single-beam Acoustic Trapping: A Promising Tool for Measurements of Cell Mechanics

We demonstrate a noncontact single-beam acoustic trapping method for the quantification of the mechanical properties of a single suspended cell with label-free. Experimentally results show that the single-beam acoustic trapping force results in morphological deformation of a trapped cell. While a cancer cell was trapped in an acoustic beam focus, the morphological changes of the immobilized cell were monitored using bright-field imaging. The cell deformability was then compared with that of a trapped polystyrene microbead as a function of the applied acoustic pressure for a better understanding of the relationship between the pressure and degree of cell deformation. Cell deformation was found to become more pronounced as higher pressure levels were applied. Furthermore, to determine if this acoustic trapping method can be exploited in quantifying the cell mechanics in a suspension and in a non-contact manner, the deformability levels of breast cancer cells with different degrees of invasiveness due to acoustic trapping were compared. It was found that highly-invasive breast cancer cells exhibited greater deformability than weakly-invasive breast cancer cells. These results clearly demonstrate that the single-beam acoustic trapping technique is a promising tool for non-contact quantitative assessments of the mechanical properties of single cells in suspensions with label-free.1